Busan, South Korea
Busan, South Korea

Pusan National University is one of ten flagship Korean national universities and a leading university in South Korea. Located mainly in Busan , the university's English name is a translation of its former Korean name, "Gungnip Pusan Daehakgyo" , but has since dropped "national" from its Korean moniker. Continually ranked among one of top 500 world universities by ARWU World University Ranking and QS Top Universities Ranking, Pusan National University is one of only ten Korean universities ranked in both ARWU World University Ranking and QS Top Universities Ranking in 2010. In QS Top Universities Ranking 2010, Pusan National University is ranked in top five in social science and management, sixth in engineering and technology, sixth in life science and medicine, and ninth in arts and humanities among Korean universities. Pusan National University is one of only five Korean universities ranked in four subject areas in QS Top Universities Ranking 2010. Wikipedia.

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A nanoenergetic material composite having a remote ignition characteristic by a high-power pulsed laser beam is prepared by adding various contents of multiwalled carbon nanotubes (MWCNTs) to a nanoenergetic composite material (nEM) to enable remote ignition by a high-power laser beam. The nanoenergetic material composite is a MWCNT/nEM composite powder prepared by adding multiwalled carbon nanotubes to the nanoenergetic material, which is a mixture of fuel material nanoparticles and metal oxidizer nanoparticles, wherein the multiwalled carbon nanotubes enhance a combustion rate of the MWCNT/nEM composite powder by delivering thermal energy upon remote optical ignition by the high-power pulsed laser beam.

Pusan National University | Date: 2015-04-13

In one aspect of the present disclosure, there is provided a thermoelectric device comprising: a closed-loop flow channel configured to allow a liquid electrolyte to circulate therein and therealong in one direction; an electrolyte flow activator configured to activate the liquid electrolyte circulation along the flow channel; a first electrode disposed at a first position of the flow channel; and a second electrode disposed at a second position of the flow channel, wherein the first and second positions are different, wherein the liquid electrolyte has a redox reaction due to a temperature difference between the first electrode and the second electrode.

Pusan National University | Date: 2015-12-03

Provided are a diamine compound, a polyamic acid and polyimide using the same. The diamine monomer compound is useful for preparing a transparent polyamic acid and polyimide having a high refractive index and a low birefringence.

LG Corp and Pusan National University | Date: 2016-07-08

The present invention relates to a motor driving apparatus and a home appliance including the same. A motor driving apparatus according to an embodiment of the present invention includes an inverter for converting a DC voltage of a DC-link capacitor into an AC voltage according to a switching operation and outputting the converted AC voltage to a motor; a DC-link resistor disposed between the DC-link capacitor and the inverter; and a controller for controlling the inverter based on a phase current sampled through the DC-link resistor, wherein the controller estimates a phase current based on the phase current sampled through the DC link resistor, in an interval in which phase current detection is not possible. Thereby, the phase current flowing through the motor may be accurately calculated using the DC link resistor.

Green Cross and Pusan National University | Date: 2017-04-05

A composition containing wall teichoic acid-attached peptidoglycan (WTA-PGN) as an active ingredient, a method for preventing or treating Staphylococcus aureus infectious diseases using the composition, and a method for preparing a soluble WTA-PGN which can be used as an active ingredient in the composition are provided. The composition of the present invention can be effectively used for preventing or treating Staphylococcus aureus infectious diseases by opsonophagocytosis due to antigen-antibody reaction and neutrophil-mediated phagocytosis due to T cell activation at the early stage of infection.

Pusan National University | Date: 2017-01-25

The present invention relates to a nitrogen oxide-releasing wound treatment film and a preparation method therefor. A nitrogen oxide-releasing film containing S-nitroglutathione, which is a nitrogen oxide donor to be spontaneously formed in the human body, has mechanical characteristics enabled to be applied to the human body, slowly releases nitrogen oxide and inhibits a pathogen, which is the main cause of wound infection, and can quickly heal a wound, and thus the film can be useful for treating a wound.

Wang M.,South China University of Technology | Ge S.S.,National University of Singapore | Ge S.S.,University of Electronic Science and Technology of China | Hong K.-S.,Pusan National University
IEEE Transactions on Neural Networks | Year: 2010

This paper presents adaptive neural tracking control for a class of non-affine pure-feedback systems with multiple unknown state time-varying delays. To overcome the design difficulty from non-affine structure of pure-feedback system, mean value theorem is exploited to deduce affine appearance of state variables xi as virtual controls αi and of the actual control The separation technique is introduced to decompose unknown functions of all time-varying delayed states into a series of continuous functions of each delayed state. The novel LyapunovKrasovskii functionals are employed to compensate for the unknown functions of current delayed state, which is effectively free from any restriction on unknown time-delay functions and overcomes the circular construction of controller caused by the neural approximation of a function of and mathdotu. Novel continuous functions are introduced to overcome the design difficulty deduced from the use of one adaptive parameter. To achieve uniformly ultimate boundedness of all the signals in the closed-loop system and tracking performance, control gains are effectively modified as a dynamic form with a class of even function, which makes stability analysis be carried out at the present of multiple time-varying delays. Simulation studies are provided to demonstrate the effectiveness of the proposed scheme. © 2006 IEEE.

Talkner P.,University of Augsburg | Morillo M.,University of Seville | Yi J.,Pusan National University | Hanggi P.,University of Augsburg
New Journal of Physics | Year: 2013

Work performed on a system in a microcanonical state by changes in a control parameter is characterized in terms of its statistics. The transition probabilities between eigenstates of the system Hamiltonians at the beginning and the end of the parameter change obey a detailed balance-like relation from which various forms of the microcanonical fluctuation theorem are obtained. As an example, sudden deformations of a two-dimensional harmonic oscillator potential are considered, and the validity of the microcanonical Jarzynski equality connecting the degrees of degeneracy of energy eigenvalues before and after the control parameter change is confirmed. © IOP Publishing and Deutsche Physikalische Gesellschaft.

Kim K.H.,Pusan National University
Journal of Pharmacology and Experimental Therapeutics | Year: 2014

The present study was undertaken to determine the underlying mechanism of silibinin-induced cell death in human breast cancer cell lines MCF7 and MDA-MB-231. Silibinin-induced cell death was attenuated by antioxidants, N-Acetylcysteine (NAC) and 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid, suggesting that the effect of silibinin was dependent on generation of reactive oxygen species (ROS). Western blot analysis showed that silibinin induced downregulation of extracellular signal-regulated kinase (ERK) and Akt. When cells were transiently transfected with constitutively active (ca)mitogen-Activated protein kinase (MEK), an upstream kinase of ERK and caAkt, they showed resistance to silibinin-induced cell death. Silibinin decreased the cleavage of Notch-1 mRNA and protein levels. Notch- 1-overexpressed cells were resistant to the silibinin-induced cell death. Inhibition of Notch-1 signaling was dependent on ROS generation. Overexpression of Notch-1 prevented silibinin-induced inhibition of ERK and Akt phosphorylation. Silibinin-induced cell death was accompanied by increased cleavage of caspase-3 and was prevented by caspase-3 inhibitor in MDA-MB-231 cells but not in MCF7 cells. Silibinin induced translocation of apoptosisinducing factor (AIF), which was blocked by NAC, and transfection of caMEK and caAkt. Silibinin-induced cell death was prevented by silencing of AIF expression using small interfering AIF RNA in MCF7 cells but not in MDA-MB-231 cells. In conclusion, silibinin induces cell death through an AIF-dependent mechanism in MCF7 cells and a caspase-3-dependent mechanism in MDA-MB-231 cells, and ROS generation and Notch-1 signaling act upstream of the ERK and Akt pathway. These data suggest that silibinin may serve as a potential agent for induction of apoptosis in human breast cancer cells.Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Lee H.,Kyung Hee University | Choi T.-Y.,Korea Institute of Oriental Medicine | Lee M.S.,Korea Institute of Oriental Medicine | Shin B.-C.,Pusan National University
Clinical Journal of Pain | Year: 2013

Although acupuncture has been frequently used for acute nonspecific low back pain (LBP), relevant systematic reviews indicate sparse and inconclusive evidence. This systematic review aimed at critically evaluating the evidence for/against acupuncture for acute LBP. METHODS:: We searched Medline, Central, Embase, 2 Chinese databases, relevant journals, and trial registries for the randomized-controlled trials of acupuncture that involved needling for acute/subacute LBP. Risk of bias was assessed using the assessment tool from the Cochrane Back Review Group and the adequacy of acupuncture intervention was evaluated by 2 independent reviewers. The studies according to the control types were combined using a random-effects model. RESULTS:: A total of 11 randomized-controlled trials (n=1139) were included. Compared with nonsteroidal anti-inflammatory drugs, acupuncture may more effectively improve symptoms of acute LBP (5 studies; risk ratio, 1.11; 95% confidence interval: 1.06, 1.16). For pain, there exists inconsistent evidence that acupuncture is more effective than medication. Compared with sham acupuncture, acupuncture may more effectively relieve pain (2 studies; mean difference,-9.38; 95% confidence interval:-17.00,-1.76) but not function/disability. Acupuncture appears to be associated with few side effects but the evidence is limited. DISCUSSION:: The current evidence is encouraging in that acupuncture may be more effective than medication for symptom improvement or relieve pain better than sham acupuncture in acute LBP. The present findings should be confirmed by future studies that overcome the methodological limitations of the studies evaluated in our review. © 2013 by Lippincott Williams and Wilkins.

Suttangkakul A.,University of Wisconsin - Madison | Suttangkakul A.,Kasetsart University | Li F.,University of Wisconsin - Madison | Chung T.,Pusan National University | Vierstra R.D.,University of Wisconsin - Madison
Plant Cell | Year: 2011

Autophagy is an intracellular recycling route in eukaryotes whereby organelles and cytoplasm are sequestered in vesicles, which are subsequently delivered to the vacuole for breakdown. The process is induced by various nutrient-responsive signaling cascades converging on the Autophagy-Related1 (ATG1)/ATG13 kinase complex. Here, we describe the ATG1/13 complex in Arabidopsis thaliana and show that it is both a regulator and a target of autophagy. Plants missing ATG13 are hypersensitive to nutrient limitations and senesce prematurely similar to mutants lacking other components of the ATG system. Synthesis of the ATG12-ATG5 and ATG8-phosphatidylethanolamine adducts, which are essential for autophagy, still occurs in ATG13-deficient plants, but the biogenesis of ATG8-decorated autophagic bodies does not, indicating that the complex regulates downstream events required for autophagosome enclosure and/or vacuolar delivery. Surprisingly, levels of the ATG1a and ATG13a phosphoproteins drop dramatically during nutrient starvation and rise again upon nutrient addition. This turnover is abrogated by inhibition of the ATG system, indicating that the ATG1/13 complex becomes a target of autophagy. Consistent with this mechanism, ATG1a is delivered to the vacuole with ATG8-decorated autophagic bodies. Given its responsiveness to nutrient demands, the turnover of the ATG1/13 kinase likely provides a dynamic mechanism to tightly connect autophagy to a plant's nutritional status. © 2011 American Society of Plant Biologists. All rights reserved.

Bae C.Y.,Pusan National University | Park J.H.,Pusan National University | Kim E.Y.,Pusan National University | Kang Y.S.,Sogang University | Kim B.K.,Pusan National University
Journal of Materials Chemistry | Year: 2011

Various amounts of silica nanoparticles were chemically incorporated into amorphous polyurethanes (PU) of two different molecular weights by sol-gel reactions, and the effects were studied in terms of mechanical, dynamic mechanical, dual, and triple shape memory effects (DSME and TSME) of the nanocomposite films. It was found that the silica particles act as multifunctional cross-links as well as reinforcing fillers and significantly augmented the glassy and rubbery state moduli, yield strength, break strength, glass transition temperature, and dual shape memory properties. A cohesive bilayer of the two films fabricated from an interpenetrating polymer network (IPN) exhibited synergistic mechanical properties in the glassy and rubbery states along with two undisturbed glass transitions by which an intermediate plateau region and TSME were demonstrated. © 2011 The Royal Society of Chemistry.

Ku T.-W.,Pusan National University | Kang B.-S.,Pusan National University
Materials and Design | Year: 2013

As an important load-supporting automobile part that transmits torque between the transmission and the driven wheel, the outer race of CV (constant velocity) joints with six inner ball grooves has been conventionally produced by the multi-stage warm forging processes, which involves several operations including forward extrusion, upsetting, backward extrusions, sizing and necking, as well as additional machining. There is still no choice but to produce the complex shaped components other than by this warm forging process. As an alternative, multi-stage cold forging process is presented to replace these traditional warm forging. The multi-stage cold forging procedure is first considered through a process assessment regarding the traditional multi-stage warm forging one. Then, the process is simplified and redesigned as one operation to produce the forged outer race and the backward extrusions of the traditional process, and the sizing and necking are also combined into a single sizing-necking process. In addition, to ensure the appropriateness of the suggested process with respect to deformation behavior, a 3-dimensional finite element simulation on each sequence is performed, and experimental investigations are also carried out using SCr420H as the initial billet material. Finally, a comparative investigation of the process duration between the traditional multi-stage warm forging and the suggested multi-stage cold forging is presented. It is shown that the multi-stage cold forging process in this study could be successfully applied to the mass production of the outer race of the CV joints with the appreciably reduced processing duration for the machining process on the inner ball groove. © 2013 Elsevier Ltd.

Nguyen V.D.,National University of Singapore | Kim K.H.,Pusan National University
IEEE Transactions on Intelligent Transportation Systems | Year: 2013

In port container terminals, containers are transported between vessels and storage blocks by transporters. To improve the utilization of transporters and the operational efficiency of container terminals, the pooling strategy is widely applied, and transporters in the same pool are shared by a group of quay cranes (QCs). This paper compares various strategies for constructing the pools: one pool for each QC, one pool for all the QCs deployed to each vessel, one pool for all the QCs for multiple adjacent vessels, and one pool for all the operating QCs in the terminal. Various heuristic algorithms (HAs) to construct pools of transporters are suggested and evaluated in terms of the total delay time of QC operation and the total travel distance of transporters. In addition, opportunities for dual-command-cycle operation are analyzed for each of these heuristic rules by using different data sets of QC operations. Various scenarios of QC operation are generated, and the HAs are compared in terms of their performance through a simulation study. © 2000-2011 IEEE.

Oh S.,Pohang University of Science and Technology | Ryu K.,Pusan National University
Computers and Industrial Engineering | Year: 2013

Because the supply network of an enterprise should be flexible enough to capture and overcome market dynamics, one of the major concerns of global enterprises is to make their supply network reconfigurable. Although many strategies for flexible management of a supply network have been proposed, especially for mitigating supply network risks, it still remains unclear how to apply the strategies to a supply network and how to reconfigure the supply network. This paper examines the influence of flexibility strategies in a dynamic global market environment on the structure of supply network, and proposes a method of reconfiguring the supply network of an enterprise to cope with its flexibility strategies. A reconfigurable supply network model is proposed, and flexibility strategies are classified, and critical indices of strategies are defined. In the proposed model, each business actor is defined as a network node and each node has its own goal. A node optimizes its goal to reduce and overcome the risk of market environments. The result of optimization indicates that the supply network structure is reconfigured dynamically. © 2011 Elsevier Ltd. All rights reserved.

Hu X.-S.,Pusan National University | Hong K.-S.,Pusan National University | Ge S.S.,Pusan National University | Ge S.S.,National University of Singapore
Journal of Neural Engineering | Year: 2012

Deception involves complex neural processes in the brain. Different techniques have been used to study and understand brain mechanisms during deception. Moreover, efforts have been made to develop schemes that can detect and differentiate deception and truth-telling. In this paper, a functional near-infrared spectroscopy (fNIRS)-based online brain deception decoding framework is developed. Deploying dual-wavelength fNIRS, we interrogate 16 locations in the forehead when eight able-bodied adults perform deception and truth-telling scenarios separately. By combining preprocessed oxy-hemoglobin and deoxy-hemoglobin signals, we develop subject-specific classifiers using the support vector machine. Deception and truth-telling states are classified correctly in seven out of eight subjects. A control experiment is also conducted to verify the deception-related hemodynamic response. The average classification accuracy is over 83.44% from these seven subjects. The obtained result suggests that the applicability of fNIRS as a brain imaging technique for online deception detection is very promising. © 2012 IOP Publishing Ltd.

Hu X.-S.,Pusan National University | Hong K.-S.,Pusan National University | Ge S.S.,Pusan National University | Ge S.S.,National University of Singapore
Journal of Biomedical Optics | Year: 2013

The reduction of trial-to-trial variability (TTV) in task-evoked functional near-infrared spectroscopy signals by considering the correlated low-frequency spontaneous fluctuations that account for the resting-state functional connectivity in the brain is investigated. A resting-state session followed by a task-state session of a right hand fingertapping task has been performed on five subjects. Significant ipsilateral and bilateral resting-state functional connectivity has been detected at the subjects' motor cortex using the seed correlation method. The correlation coefficients obtained during the resting-state are used to reduce the TTV in the signals measured during the task sessions. The results suggest that correlated spontaneous low-frequency fluctuations contribute significantly to the TTV in the task evoked fNIRS signals.© 2013 Society of Photo-Optical Instrumentation Engineers.

Lee I.,Yonsei University | Seo Y.-S.,University of California at Davis | Seo Y.-S.,Pusan National University | Coltrane D.,University of California at Davis | And 5 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2011

Rice is a staple food for one-half the world's population and a model for other monocotyledonous species. Thus, efficient approaches for identifying key genes controlling simple or complex traits in rice have important biological, agricultural, and economic consequences. Here, we report on the construction of RiceNet, an experimentally tested genome-scale gene network for a monocotyledonous species. Many different datasets, derived from five different organisms including plants, animals, yeast, and humans, were evaluated, and 24 of the most useful were integrated into a statistical framework that allowed for the prediction of functional linkages between pairs of genes. Genes could be linked to traits by using guilt-by-association, predicting gene attributes on the basis of network neighbors. We applied RiceNet to an important agronomic trait, the biotic stress response. Using network guilt-by-association followed by focused protein-protein interaction assays, we identified and validated, in planta, two positive regulators, LOC-Os01g70580 (now Regulator of XA21; ROX1) and LOC-Os02g21510 (ROX2), and one negative regulator, LOC-Os06g12530 (ROX3). These proteins control resistance mediated by rice XA21, a pattern recognition receptor. We also showed that RiceNet can accurately predict gene function in another major monocotyledonous crop species, maize. RiceNet thus enables the identification of genes regulating important crop traits, facilitating engineering of pathways critical to crop productivity.

Yun W.Y.,Pusan National University | Yamamoto H.,Tokyo Metroplitan University
IIE Transactions (Institute of Industrial Engineers) | Year: 2012

This article considers a linear and circular consecutive-k-out-of-n:F system composed of n identical components with exponential failure time distributions and subjected to a total load that is equally shared by all the working components in the system. The event of a component failure results in a higher load, therefore inducing a higher failure rate, in each of the surviving components. A power rule relationship between the amount of the load shared by surviving components and the failure rate of the surviving components is assumed. The system reliability of the proposed consecutive-k-out-of-n:F system with load-sharing dependency is obtained. Three optimization problems (in which the expected cost per unit time is used as an optimization criterion) are considered to determine the system configuration n and a preventive maintenance interval. The effect of dependence parameters, the system configuration parameter k, and various cost parameters on the optimal n and maintenance interval are investigated in numerical examples. A comparison between the three problems is also performed. Accepted in 2005 for a special issue on Reliability co-edited by Hoang Pham, Rutgers University: Dong Ho Park, Hallym University, Korea; and Richard Cassady, University of Arkansas. © 2012 Copyright Taylor and Francis Group, LLC.

Im D.,Korea Advanced Institute of Science and Technology | Im D.,University of Texas at Dallas | Nam I.,Pusan National University
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2014

A low noise and highly linear wideband CMOS receiver front-end for digital TV receivers is proposed. The proposed RF front-end comprises a wideband noise canceling common gate low noise amplifier (LNA) with a capacitively cross-coupled current source, a highly linear up-conversion micromixer with third-order intermodulation distortion cancellation, and a highly linear surface acoustic wave (SAW) driver with enhanced loop gain. The RF front-end was fabricated using a 0.13 μ m CMOS process and it draws 27 mA from a 1.5 V supply voltage. It achieves a voltage gain of 23 dB, a noise figure of less than 4 dB, an IIP3 of greater than ${-}$ 6.5 dBm, and an IIP2 of greater than 28 dBm across the entire input band from 54 MHz to 882 MHz. © 2014 IEEE.

He W.,National University of Singapore | Ge S.S.,National University of Singapore | How B.V.E.,National University of Singapore | Choo Y.S.,National University of Singapore | Hong K.-S.,Pusan National University
Automatica | Year: 2011

In this paper, robust adaptive boundary control for a flexible marine riser with vessel dynamics is developed to suppress the riser's vibration. To provide an accurate and concise representation of the riser's dynamic behavior, the flexible marine riser with vessel dynamics is described by a distributed parameter system with a partial differential equation (PDE) and four ordinary differential equations (ODEs). Boundary control is proposed at the top boundary of the riser based on Lyapunov's direct method to regulate the riser's vibration. Adaptive control is designed when the system parametric uncertainty exists. With the proposed robust adaptive boundary control, uniform boundedness under the ocean current disturbance can be achieved. The proposed control is implementable with actual instrumentation since all the required signals in the control can be measured by sensors or calculated by a backward difference algorithm. The state of the system is proven to converge to a small neighborhood of zero by appropriately choosing design parameters. Simulations are provided to illustrate the applicability and effectiveness of the proposed control. © 2011 Elsevier Ltd. All rights reserved.

Rehan M.,Pusan National University | Hong K.-S.,Pusan National University | Ge S.S.,National University of Singapore
Nonlinear Analysis: Real World Applications | Year: 2011

This paper discusses stabilization and tracking control using linear matrix inequalities for a class of systems with Lipschitz nonlinearities. A nonlinear state feedback stabilization control is proposed for systems containing a more general case of Lipschitz nonlinearity. The main objective of the present study is to provide, for multi-input multi-output nonlinear systems, a tracking control approach based on nonlinear state feedback, which guarantees global asymptotic output and state tracking with zero tracking error in the steady state. Further, the tracking control is formulated for optimal disturbance rejection, using L2 gain reduction based performance criteria. The proposed methodologies are illustrated herein using two simulation examples of chaotic and unstable dynamical systems. © 2010 Elsevier Ltd. All rights reserved.

Yi K.S.,University of Texas at Dallas | Yi K.S.,Pusan National University | Trivedi K.,University of Texas at Dallas | Floresca H.C.,University of Texas at Dallas | And 4 more authors.
Nano Letters | Year: 2011

Quantum confinement of carriers has a substantial impact on nanoscale device operations. We present electrical transport analysis for lithographically fabricated sub-5 nm thick Si nanowire field-effect transistors and show that confinement-induced quantum oscillations prevail at 300 K. Our results discern the basis of recent observations of performance enhancement in ultrathin Si nanowire field-effect transistors and provide direct experimental evidence for theoretical predictions of enhanced carrier mobility in strongly confined nanowire devices. © 2011 American Chemical Society.

Dang Q.-V.,University of Aalborg | Yun W.-Y.,Pusan National University | Kopfer H.,University of Bremen
Computers and Industrial Engineering | Year: 2012

Owing to trade imbalance, shipping companies position empty containers between ports or depots periodically. The most difficult problem for positioning is that it is not possible to know the exact amounts of empty containers required in the future. The paper deals with the problem of positioning empty containers in a port area with multiple depots. Customer demands and returning containers in depots per unit time period are assumed to be serially-correlated and dependent random variables. Three options are considered to prepare the required extent of positioning: positioning from other overseas ports, inland positioning between depots, and leasing. The policies for empty-container management consist of three parts as follows: a coordinated, (s, S) inventory policy for positioning from other ports, (r i, R i) policy for inland positioning between depots; and a simple leasing policy with zero lead-time. For inland positioning policy, four heuristic methods are proposed to reposition empty containers between depots. The objective is to obtain optimal policies corresponding to different methods of inland positioning in order to minimize the expected total costs. A genetic-based optimization procedure is developed to find the optimal parameters (s, S) and (r i, R i). Some numerical examples and sensitivity analyses are given to demonstrate the results. © 2011 Elsevier Ltd. All rights reserved.

Moon H.S.,Pusan National University | No H.-R.,Chonnam National University
Journal of the Optical Society of America B: Optical Physics | Year: 2014

We report the physical origins of the on-resonant and off-resonant two-photon absorption (TPA) in an open-laddertype atomic system of the 5S 1?2 (F = 1)-5P3?2(F0 = 0; 1; 2)-5D5?2(F00 =1; 2; 3) transitions in 87Rb atoms. When the onresonant TPA, including electromagnetically induced transparency (EIT), was transformed into the off-resonant TPA according to the coupling laser frequency detuning, we clarified the dynamics of the atomic coherences by decomposing into the two-photon coherence (TC) and the crossover coherence (CC) terms mixed between onephoton coherence (OC) and TC terms. The physical origins of the two TPAs were completely different; the cause of the on-resonant TPA was the CC term, and that of the off-resonant TPA was the TC term. © 2014 Optical Society of America.

Cho K.S.,Kyungpook National University | Song K.-W.,Pusan National University | Chang G.-S.,FITI Testing and Research Institute
Journal of Rheology | Year: 2010

We have found empirical scaling relations in nonlinear viscoelasticity of poly(ethylene oxide) (PEO) solutions under large amplitude oscillatory shear flow. The scaling relations superpose dimensionless nonlinear viscoelastic functions, such as the normalized amplitudes of elastic and viscous stresses and normalized Fourier intensities, measured at different strain amplitudes and frequencies on a single curve irrespective of the molecular weight and the concentration of the polymer solutions. The scaling relations reveal that the nonlinear viscoelastic functions are functions of dimensionless variable ζ ≡ γo cos δ (ω), where δ is the phase lag of linear viscoelasticity. The validity of our superposition was checked for PEO aqueous solutions under the conditions that concentration: 3

Kang N.L.,Pusan National University | Choi S.D.,Kyungpook National University
Progress of Theoretical Physics | Year: 2011

Utilizing the generalized state-dependent projectors and the KC reduction identities [For the first kind, see: Prog. Theor. Phys. 96 (1996), 307, Eq. (18)] introduced by the authors, the nth-order conductivity (n = 1, 2, 3, ···) of electron systems in solids, in which electrons are scattered by background, is derived. The result for n ≥ 4 is derived by applying mathematical inference to the results obtained up to the third order by direct calculations. It is also known that the results up to the third order are applicable to general electron systems including those undergoing confinement potentials, which yield non-equispaced energy spectra, and satisfy the population criterion that the distributions of electrons and background members should be given in multiplicative forms [J. of Phys. A 43 (2010), 165203]. As the iteration-based mathematical inference taken here for deriving the result is acceptable, we may conclude that the nth-order conductivity for n ≥ 4 is also applicable to general electron systems and satisfies the population criterion.

Moon H.S.,Pusan National University | Noh H.R.,Chonnam National University
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2011

We have investigated the optical pumping effects of single-resonance optical pumping (SROP) and double-resonance optical pumping (DROP) in the ladder-type electromagnetically induced transparency (EIT) of the 5S 1/2-5P3/2-5D3/2 transition of 87Rb atoms. In the 5S1/2(F = 2)-5P3/2(F′ = 3)-5D 3/2(F″ = 2, 3) transition with the single-resonance cycling 5S1/2(F = 2)-5P3/2(F′ = 3) transition, we observed the transmittance spectrum due to DROP and EIT. Based on our experimental results investigated according to the laser power (the probe and the coupling) and the coupling laser detuning, we revealed that DROP was significant for the transmittance spectrum. Particularly, in the 5S1/2(F = 2)-5P 3/2(F′ = 1, 2)-5D3/2(F″ = 1) transition without a cycling transition, we observed the two-photon absorption due to two-photon atomic coherence, when the probe laser power was weak and the coupling laser power was strong. © 2011 IOP Publishing Ltd.

Chrobak D.,University of Silesia | Kim K.-H.,Pusan National University | Kurzydlowski K.J.,Warsaw University of Technology | Nowak R.,Aalto University
Applied Physics Letters | Year: 2013

Recent findings in nanodeformation of semiconductors posed a dilemma whether the nanoscale plasticity starts with phase transformation or nucleation of dislocations in a stressed nanovolume. In this letter we demonstrate the results of nanoindentation experiments with different loading rate, which enable us to conclude on a mechanism of incipient plasticity. The recorded nanodeformation response of GaAs and Si contrasts that observed for either GaN or metallic Fe crystal, which supports the phase transformation nature of the GaAs incipient plasticity. The derived relationship between the energy barrier for defect nucleation and applied stress served as a verification of the obtained results. © 2013 AIP Publishing LLC.

Hwang S.-H.,Kyungnam University | Liu X.,Florida A&M University | Kim J.-M.,Pusan National University | Li H.,Florida A&M University
IEEE Transactions on Industrial Electronics | Year: 2013

This paper proposes a distributed digital control architecture of a modular-based solid-state transformer (SST) using a digital signal processor (DSP) and a field-programmable gate array (FPGA). In particular, the three-stage SST based on a modular structure is the topology of most interest because of its superior controllability. In order to make the modular-based SST, the digital implementation is inevitable to achieve higher performances, improved reliability, and an easy development. In addition, the modular-based SST requires enough capacity for implementing complex control algorithms, multiple interfaces, and a large number of internal variables. In this paper, a digital control platform for the modular-based SST is built using a floating-point DSP and an FPGA that operate cooperatively. As a result, the main control algorithms are performed by the DSP, and the simple logical processes are implemented in the FPGA to synthesize the suitable gating signals and control external devices, respectively. The proposed implementation method enables high-switching- frequency operation, multitasking, and flexible design for the modular-based SST. Experimental results are presented to verify the practical feasibility of the proposed technique for the modular-based SST. © 2012 IEEE.

Min J.K.,Pusan National University | Park I.S.,Kyungpook National University
International Journal of Heat and Mass Transfer | Year: 2011

Film flows are classified into non-wavy laminar, wavy laminar and turbulence along the Reynolds number or the flow stability. Since the wavy motions of the film flows are so intricate and nonlinear, the studies have largely been dependent upon the experimental way. The numerical approaches have been limited on the non-wavy flow regime. To track the free surface position, various numerical techniques such as the VOF (Volume of Fluids), the MAC (Marker and Cell) and the moving grid have been adopted. However those were for a more accurate estimation of the average film thickness and not for capturing the wavy motion. Because the wavy motion highly affects the heat transfer in the film flow, the profound concern for the wavy motion is significant. In this study, the wavy motions of the laminar wavy film flow with the Reynolds number 200-1000 are successfully found by the VOF and PLIC (Piecewise Linear Interface Calculation) method. The numerical results, including the average film thickness, and the wave's amplitude, frequency and velocity, are compared with the experimental results. © 2010 Elsevier Ltd. All rights reserved.

Seeley W.W.,University of California at San Francisco | Zhou J.,University of California at San Francisco | Kim E.-J.,Pusan National University
Neuroscientist | Year: 2012

The behavioral variant of frontotemporal dementia (bvFTD) slowly undermines emotion, social behavior, personal conduct, and decision making. These deficits occur in concert with focal neurodegeneration that can be quantified with modern structural and functional imaging and neuropathological methods. As a result, studies of bvFTD have helped to clarify brain structures, networks, and neurons that prove critical for normal social-emotional functioning. In this article, the authors review the evolving bvFTD literature and propose a simple, testable network-based working model for understanding bvFTD. © The Author(s) 2012.

Noh H.-R.,Chonnam National University | Moon H.S.,Pusan National University
Optics Express | Year: 2011

We present discrimination of the effect of one-photon and two-photon coherences in electromagnetically induced transparency for a three-level ladder-type atomic system. After the optical Bloch equations for a three-level atom, with either cycling or non-cycling transitions, were solved numerically, the solutions were averaged over the velocity distribution and finite transit time. Through this we were able to discriminate one-photon and two-photon coherence parts of the calculated spectra. We also found that the spectra showed peaks as the branching ratio of the intermediate (excited) state increased (decreased). The experimental results of previous reports [H. S. Moon, et al., Opt. Express 16, 12163 (2008); H. S. Moon and H. R. Noh, J. Phys. B 44, 055004 (2011)] could well be accounted for by this discrimination of one-photon and two-photon coherences in the transmittance signals for the simplified three-level atomic system. © 2011 Optical Society of America.

Moon H.S.,Pusan National University | Noh H.-R.,Chonnam National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The polarization dependence of double-resonance optical pumping (DROP) in the ladder-type electromagnetically induced transparency (EIT) of the 5S 1/2-5P3/2-5D5/2 transition of 87Rb atoms is studied. The transmittance spectra in the 5S1/2(F=2)-5P 3/2(F′=3)-5D5/2(F′ ′=2,3,4) transition were observed as caused by EIT, DROP, and saturation effects in the various polarization combinations between the probe and coupling lasers. The features of the double-structure transmittance spectra in the 5S1/2(F=2)-5P3/2(F′=3)-5D 5/2(F′′=4) cycling transition were attributed to the difference in saturation effect according to the transition routes between the Zeeman sublevels and the EIT according to the two-photon transition probability. © 2011 American Physical Society.

Noh H.-R.,Chonnam National University | Moon H.S.,Pusan National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We present a diagrammatic method for complete characterization of multiphoton processes in three-level atomic systems. By considering the interaction routes of the coupling and probe photons for a ladder-type, three-level, noncycling (or cycling) atomic system, we are able to completely discriminate between the pure one-photon and the pure two-photon resonance effects, and the effect of their combination in electromagnetically induced transparency (EIT) using our diagrammatic method. We show that the proposed diagrammatic method is very useful for the analysis of multiphoton processes in ladder-type EIT. © 2011 American Physical Society.

Moon H.S.,Pusan National University | Noh H.-R.,Chonnam National University
Optics Express | Year: 2013

We have experimentally and theoretically studied resonant twophoton absorption (TPA) and electromagnetically induced transparency (EIT) in the open ladder-type atomic system of the 5S1/2 (F = 1)-5P3/2 (F' = 0, 1, 2)-5D5/2 (F" = 1, 2, 3) transitions in 87Rb atoms. As the coupling laser intensity was increased, the resonant TPA was transformed to EIT for the 5S1/2 (F = 1)-5P3/2 (F' = 2)-5D5/2 (F" = 3) transition. The transformation of resonant TPA into EIT was numerically calculated for various coupling laser intensities, considering all the degenerate magnetic sublevels of the 5S1/2- 5P3/2-5D5/2 transition. From the numerical results, the crossover from TPA to EIT could be understood by the decomposition of the spectrum into an EIT component owing to the pure two-photon coherence and a TPA component caused by the mixed term. © 2013 Optical Society of America.

Kang N.L.,Pusan National University | Choi S.D.,Kyungpook National University
Journal of Physics A: Mathematical and Theoretical | Year: 2010

A new nonlinear optical conductivity formula for a system of electrons interacting with phonons was derived using a reduction identity and a state-dependent projection technique introduced by the authors. The results include a general formula for the nonlinear optical conductivity of the general rank and the linear, first-order nonlinear and second-order nonlinear conductivity are calculated in terms of the linewidth. The linewidth term includes the electron and phonon distribution functions properly. Therefore, it is possible to explain the phonon emission and absorption in all electron transition processes in an organized manner. © 2010 IOP Publishing Ltd.

Chung C.-W.,University of Illinois at Urbana - Champaign | Shon C.-S.,Texas A&M University | Kim Y.-S.,Pusan National University
Construction and Building Materials | Year: 2010

This research focuses on investigating the durability of concretes containing fly ash and silica fume exposed to combined mode of deterioration. For this purpose, the chloride ion diffusivity of concrete was evaluated before and after 300 freeze-thaw (F-T) cycles. It was found that the coefficient of chloride ion diffusivity (CCID) increased as water to cementitious material ratio (w/cm) and air content increased. Test results clearly showed that CCID for all concretes increased after F-T cycles. In addition, concrete incorporating silica fume showed the lowest CCID and highest durability factor (DF), regardless of curing regime, air content, and w/cm. However, fly ash concrete showed good resistance to chloride ion diffusivity before and after F-T cycles when low w/cm as well as a proper curing and air content were provided. © 2010 Elsevier Ltd. All rights reserved.

Noh H.-R.,Chonnam National University | Moon H.S.,Pusan National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We clarify an interpretation of transmittance signals in ladder-type atomic systems by discriminating the contributions of one-photon resonance, two-photon resonance, and a mixed term of both in the calculated spectra for these ladder-type multilevel atoms. When the two-photon-resonance effect is distinguished from an accurate spectrum calculated by modeling ladder-type electromagnetically-induced transparency for the 5S 1/2-5P 3/2-5D 5/2 transitions of 87Rb atoms, we find that the transmittance signals for the 5D 5/2(F ′ ′=2,3) states are mainly composed of the mixed term related not to pure-two-photon atomic coherence but to the optical-pumping effect whereas the transmittance signal for the 5D 5/2(F ′ ′=4) state originates from both the pure-two-photon-resonance term and the mixed term. © 2012 American Physical Society.

Chun H.-H.,Pusan National University | Jo W.-K.,Kyungpook National University
Journal of Industrial and Engineering Chemistry | Year: 2014

Polymer-supported TiO2 nanofibers with different polyvinylpyrrolidone (PVP)-to-TiO2 (PT) ratios were synthesized and their photocatalytic efficiencies were examined for the decomposition of trichloroethylene (TCE). The spectral results of the TiO2 nanofibers confirmed the presence of TiO2 crystal phases in the nanofibers. The TiO2 nanofiber with the highest PT ratio of 1:1.3 showed the highest TCE decomposition (94%), followed by TiO2 nanofibers with PT ratios of 1:0.7 (91%), 1:0.35 (88%), and 1:0.1 (84%). The conditions of low input concentration and humidity were suggested for the optimal decomposition of TCE. Consequently, the TiO2 nanofiber webs could be used effectively to decompose TCE. © 2013 The Korean Society of Industrial and Engineering Chemistry.

Kang N.L.,Pusan National University | Choi S.D.,Kyungpook National University
AIP Advances | Year: 2012

A projection-diagram method is introduced for optical conductivity with lineshape functions, which takes into account the population criterion that the electron and phonon distribution functions are multiplicatively combined along with the energy conservation factors for proper interpretation of emission and absorption of phonons and photons in all the processes of electron transitions. It is further shown that the second order nonlinear optical conductivity of the system of electrons interacting with phonons, obtained using this method, is identical with that derived by using the state dependent projectors and the KC reduction identities [J. Phys. A: Math. Theor. 43, 165203 (2010)]. We expect that this method can reduce the amount of many-body calculation and can be of help in providing physical intuition into solid state quantum dynamics and representing perturbation expressions for such systems. Copyright © 2012 Author(s).

Moon H.S.,Pusan National University | Noh H.-R.,Chonnam National University
Journal of the Optical Society of America B: Optical Physics | Year: 2012

We have experimentally and theoretically studied the causes of the transparency spectra of the 5S1/2-5P3/2-4D5/2 and 5S1/2-5P3/2-5D5/2 transitions of 87Rb atoms. Although, the two-photon resonance of the 5S 1/2-5P3/2-4D5/2 transition was not Doppler-free in an Rb vapor, we observed the transparency phenomenon in this transition. The main cause of the transparency of the 5S1/2-5P3/2-4D 5/2 transition was double-resonance optical pumping (DROP) due to two-step excitation, and that of the 5S1/2-5P3/2-5D 5/2 transition was DROP and electromagnetically induced transparency due to two-photon coherence. We confirmed the experimental results with theoretical results calculated using the density matrix equations considering all the degenerate magnetic sublevels of both transitions of the 87Rb atoms. © 2012 Optical Society of America.

Choi K.-Y.,Pusan National University | Yaguna C.E.,Autonomous University of Madrid
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We consider the three-body decays of gravitino dark matter in supersymmetric scenarios with bilinear R-parity violation. In particular, gravitino decays into ℓW* (ℓff̄′) and νZ* (νff̄) are examined for gravitino masses below MW. After computing the gravitino decay rates into these three-body final states and studying their dependence on supersymmetric parameters, we find that these new decay modes are often more important than the two-body decay, into a photon and a neutrino, considered in previous works. Consequently, the gravitino lifetime and its branching ratios are substantially modified, with important implications for the indirect detection of gravitino dark matter. © 2010 The American Physical Society.

Lee J.W.,Pusan National University | Kim I.T.,Kyungpook National University
Japanese Journal of Ophthalmology | Year: 2010

Purpose: To compare visual acuity and macular morphology after epiretinal membrane (ERM) removal with and without internal limiting membrane (ILM) peeling. Methods: We studied a retrospective interventional case series of 40 eyes in 40 patients with ERM. All patients underwent standard three-port pars plana vitrectomy. In 19 eyes, the ERM alone was removed. In 21 eyes, the ERM was removed and ILM peeling was performed. Results: Mean best-corrected visual acuity improved significantly in both the non-ILM peeling and the ILM peeling groups (P = 0.001, P = 0.000). Mean central macular thickness (CMT) decreased significantly in both groups (P = 0.001, P = 0.001). However, there was a signifi cant difference in postoperative CMT between the two groups (P = 0.025). The mean postoperative CMT was significantly higher in the ILM peeling group than in the non-ILM peeling group. Sixteen eyes (84.2%) in the non-ILM peeling group had a normal foveal contour with a foveal depression on postoperative optical coherence tomography (OCT), while nine eyes (42.9%) in the ILM peeling group had a foveal depression (P = 0.01). Conclusions: Postoperative OCT revealed that thickening of the macula with loss of the normal foveal contour was more frequent in the ILM peeling group. However, these morphological differences did not result in functional differences in terms of visual outcome. Jpn J Ophthalmol 2010;54:129-134 © Japanese Ophthalmological Society 2010.

Kyhm K.,Pusan National University | Je K.-C.,Anyang University, South Korea | Taylor R.A.,University of Oxford
Optics Express | Year: 2012

We propose an amplified all-optical polarization phase modulator assisted by a local surface plasmon in Au-hybrid CdSe quantum dots. When the local surface plasmon of a spherical Au quantum dot is in resonance with the exciton energy level of a CdSe quantum dot, a significant enhancement of the linear and nonlinear refractive index is found in both the real and imaginary terms via the interaction with the dipole field of the local surface plasmon. Given a gating pulse intensity, an elliptical polarization induced by the phase retardation is described in terms of elliptical and rotational angles. In the case that a larger excitation than the bleaching intensity is applied, the signal light can be amplified due to the presence of gain in the CdSe quantum dot. This enables a longer propagation of the signal light relative to the metal loss, resulting in more feasible polarization modulation. © 2012 Optical Society of America.

Electronics, Telecommunications Research Institute, Chonnam National University and Pusan National University | Date: 2012-04-11

The present invention relates to a method and apparatus for spatial multiplexing transmission using multiple antennas. The method for spatial multiplexing transmission includes the steps of: assigning different transmission power weights to sequentially transmitted signals in a cross-coupled fashion; precoding the sequentially transmitted signals assigned with the transmission power weights; converting the precoded sequentially transmitted signals into parallel transmitted signals; inputting, in a cross-coupled fashion, the parallel transmitted signals into a first amplifier connected to a first antenna constituting the multiple antennas and a second amplifier connected to a second antenna constituting the multiple antennas. According to the present invention, the reception range for a signal to be transmitted to each antenna constituting the multiple antennas can be adjusted to be equal.

Choi K.,Center for Theoretical Physics of the Universe | Chun E.J.,Korea Institute for Advanced Study | Im S.H.,Center for Theoretical Physics of the Universe | Jeong K.S.,Pusan National University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We propose a new mechanism to suppress the axion isocurvature perturbation, while producing the right amount of axion dark matter, within the framework of supersymmetric axion models with the axion scale induced by supersymmetry breaking. The mechanism involves an intermediate phase transition to generate the Higgs μ-parameter, before which the weak scale is comparable to the axion scale and the resulting stronger QCD yields an axion mass heavier than the Hubble scale over a certain period. Combined with that the Hubble-induced axion scale during the primordial inflation is well above the intermediate axion scale at present, the stronger QCD in the early Universe suppresses the axion fluctuation to be small enough even when the inflationary Hubble scale saturates the current upper bound, while generating an axion misalignment angle of order unity. © 2015 The Authors.

Noh H.-R.,Chonnam National University | Moon H.S.,Pusan National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

We present a theoretical study of three-photon electromagnetically induced absorption for a ladder-type three-level atomic system. A probe beam was tuned to the lower line and two counterpropagating, linearly polarized coupling beams were tuned to the upper line. The system can be modeled with a three- (or five-) level scheme when the polarization directions of the coupling beams are parallel (or perpendicular). By calculating the absorption coefficients analytically for the two schemes, we found that the corresponding absorption coefficients were identical except for different transition strengths, and that the primitive scheme embedded in those schemes was a simple four-level scheme. © 2015 American Physical Society.

Noh H.-R.,Chonnam National University | Moon H.S.,Pusan National University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

This paper reports a theoretical study on the transmission spectra of an arbitrarily polarized laser beam through a rubidium cell with or without a buffer gas in Hanle-type coherent population trapping (CPT). This study examined how laser polarization, transverse magnetic field, and collisions with buffer gas affects the spectrum. The transmission spectrum due to CPT and the absorption spectrum due to the level crossing absorption (LCA) were calculated according to the laser polarization. The results show that the LCA is strongly dependent on the transverse magnetic field and interaction time of the atoms with a laser light via collisions with the buffer gas. In addition, the spectral shape of the calculated Hanle spectrum is closely related to the direction between the (stray) transverse magnetic field and polarization of the laser. © 2010 The American Physical Society.

Choi K.-D.,Pusan National University | Lee H.,Keimyung University | Kim J.-S.,Seoul National University
Current Opinion in Neurology | Year: 2013

PURPOSE OF REVIEW: The aim of this study is to review the recent findings on the prevalence, clinical features, and diagnosis of vertigo from brainstem and cerebellar strokes. RECENT FINDINGS: Patients with isolated vertigo are at higher risk for stroke than the general population. Strokes involving the brainstem and cerebellum may manifest as acute vestibular syndrome, and acute isolated audiovestibular loss may herald impending infarction in the territory of the anterior inferior cerebellar artery. Appropriate bedside evaluation is superior to MRI for detecting central vestibular syndromes. Recording of vestibular-evoked myogenic potentials is useful for evaluation of the central otolithic pathways in brainstem and cerebellar strokes. SUMMARY: Accurate identification of isolated vascular vertigo is very important since misdiagnosis of acute stroke may result in significant morbidity and mortality, whereas overdiagnosis of vascular vertigo would lead to unnecessary costly work-ups and medication. © 2013 Wolters Kluwer Health | Lippincott Williams &Wilkins.

Lee Y.-S.,Pusan National University | Noh H.-R.,Chonnam National University | Moon H.S.,Pusan National University
Optics Express | Year: 2015

We investigated the relationship between two- and three-photon coherence in terms of the transition routes and coupling field intensities in a Doppler-broadened ladder-type atomic system for the 5S1/2-5P3/2-5D5/2 transition in 87Rb atoms. Three-photon electromagnetically induced absorption (TPEIA) due to three-photon coherence was observed in the only transition route that exhibited a dominant two-photon coherence effect. We showed that two-photon coherence is a necessary condition for three-photon coherence phenomena. A comparison of the relative magnitudes of the electromagnetically induced transparency and TPEIA as a function of the coupling field intensity revealed that the increase of three-photon coherence was faster than that of two-photon coherence. Considering three-photon coherence in a Doppler-broadened ladder-type three-level atomic system, the relation between two- and three-photon coherence was numerically calculated. © 2015 Optical Society of America.

Wuest S.C.,U.S. National Institutes of Health | Edwan J.H.,U.S. National Institutes of Health | Martin J.F.,U.S. National Institutes of Health | Han S.,U.S. National Institutes of Health | And 7 more authors.
Nature Medicine | Year: 2011

Although previous studies have described CD25 expression and production of interleukin-2 (IL-2) by mature dendritic cells (mDCs), it remains unclear how these molecules participate in the activation of T cells. In search of the mechanisms by which daclizumab, a humanized monoclonal antibody against CD25, inhibits brain inflammation in multiple sclerosis, we observed that although the drug has limited effects on polyclonal T cell activation, it potently inhibits activation of antigen-specific T cells by mDCs. We show that mDCs (and antigen-experienced T cells) secrete IL-2 toward the mDC-T cell interface in an antigen-specific manner, and mDCs 'lend' their CD25 to primed T cells in trans to facilitate early high-affinity IL-2 signaling, which is crucial for subsequent T cell expansion and development of antigen-specific effectors. Our data reveal a previously unknown mechanism for the IL-2 receptor system in DC-mediated activation of T cells. © 2011 Nature America, Inc. All rights reserved.

Kim J.-H.,Pusan National University | Song C.E.,KAIST | Kang I.-N.,Catholic University of Korea | Shin W.S.,Korea Research Institute of Chemical Technology | Hwang D.-H.,Pusan National University
Chemical Communications | Year: 2013

A new, low band-gap donor-acceptor-type conjugated polymer, PDPP-PER, comprising 3,9-perylene (PER) and diketopyrrolo[3,4-c]pyrrole (DPP) was synthesized. The crystallinity of the synthesized polymer film significantly improved with thermal annealing to 150°C. The PCE of the PDPP-PER device reached 6.35% with a high open-circuit voltage of 0.79 V. © 2013 The Royal Society of Chemistry.

Hong D.K.,Pusan National University | Hong D.K.,Pohang University of Science and Technology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We consider fermionic dense matter under a magnetic field, where fermions couple minimally to gauge fields, and calculate anomalous currents at one loop. We find anomalous currents are spontaneously generated along the magnetic field but fermions only in the lowest Landau level contribute to anomalous currents. We then show that there are no more corrections to the anomalous currents from two or higher loops. © 2011 Elsevier B.V.

Son J.Y.,Pohang University of Science and Technology | Kim C.H.,Pusan National University | Cho J.H.,Pusan National University | Shin Y.-H.,University of Ulsan | Jang H.M.,Pohang University of Science and Technology
ACS Nano | Year: 2010

We report on the ferromagnetism of conducting filaments formed in a NiO thin film, which exhibited a typical bistable resistive switching characteristic. The NiO thin film showed an antiferromagnetic hysteresis loop for a high resistive state (ROFF). However, for a low resistive state (RON), the conducting filaments exhibited a ferromagnetic hysteresis loop for the field cooling. The ferromagnetic hysteresis behavior of the R ON state reveals switchable exchange coupling between the ferromagnetic Ni conducting filaments and the antiferromagnetic NiO layer. © 2010 American Chemical Society.

Seo K.-H.,Pusan National University | Ok J.,Pusan National University | Son J.-H.,Pusan National University | Cha D.-H.,Ulsan National Institute of Science and Technology
Journal of Climate | Year: 2013

Future changes in the East Asian summer monsoon (EASM) are estimated from historical and Representative Concentration Pathway 6.0 (RCP6) experiments of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The historical runs show that, like the CMIP3 models, the CMIP5 models produce slightly smaller precipitation. A moisture budget analysis illustrates that this precipitation deficit is due to an underestimation in evaporation and ensuing moisture flux convergence. Of the two components of the moisture flux convergence (i.e., moisture convergence and horizontal moist advection), moisture convergence associated with mass convergence is underestimated to a greater degree. Precipitation is anticipated to increase by 10%-15% toward the end of the twenty-first century over the major monsoonal front region. A statistically significant increase is predicted to occur mostly over the Baiu region and to the north and northeast of the Korean Peninsula. This increase is attributed to an increase in evaporation and moist flux convergence (with enhanced moisture convergence contributing the most) induced by the northwestward strengthening of the North Pacific subtropical high (NPSH), a characteristic feature of the future EASM that occurred in CMIP5 simulations. Along the northern and northwestern flank of the strengthened NPSH, intensified southerly or southwesterly winds lead to the increase in moist convergence, enhancing precipitation over these areas. However, future precipitation over the East China Sea is projected to decrease. In the EASM domain, a local mechanism prevails, with increased moisture and moisture convergence leading to a greater increase in moist static energy in the lower troposphere than in the upper troposphere, reducing tropospheric stability. © 2013 American Meteorological Society.

Zhu Y.,Pusan National University | Chandra P.,Pusan National University | Song K.-M.,Pohang University of Science and Technology | Ban C.,Pohang University of Science and Technology | Shim Y.-B.,Pusan National University
Biosensors and Bioelectronics | Year: 2012

Highly sensitive label-free detection of kanamycin is achieved with an aptamer sensor based on a conducting polymer/gold self-assembled nanocomposite. The sensor probe is fabricated by covalently immobilizing an in vitro selected DNA aptamer for kanamycin onto gold nanoparticle (AuNP)-comprised conducting polymer, poly-[2, 5-di-(2-thienyl)-1. H-pyrrole-1-(p-benzoic acid)] (poly-DPB). The self-assembling of DPB on AuNP is investigated by TEM and UV-vis spectroscopy and the modification of the aptamer sensor is characterized using XPS and electrochemical impedance spectroscopy. The probe is applied to detect kanamycin by using voltammetric techniques. The sensor shows a pair of redox peaks around 0.26/ 0.08. V (vs. Ag/AgCl) for kanamycin captured by the aptamer-immobilized probe. The parameters that can affect the response, such as aptamer concentration, incubation time, temperature, and pH are optimized. The calibration plot shows a linear range from 0.05 μM to 9.0 μM kanamycin with a detection limit of 9.4±0.4. nM. The proposed aptamer sensor is examined with a real sample. © 2012 Elsevier B.V.

Skinner J.J.,University of Pennsylvania | Skinner J.J.,University of Chicago | Lim W.K.,Pusan National University | Bedard S.,University of Pennsylvania | And 2 more authors.
Protein Science | Year: 2012

To examine the relationship between protein structural dynamics and measurable hydrogen exchange (HX) data, the detailed exchange behavior of most of the backbone amide hydrogens of Staphylococcal nuclease was compared with that of their neighbors, with their structural environment, and with other information. Results show that H-bonded hydrogens are protected from exchange, with HX rate effectively zero, even when they are directly adjacent to solvent. The transition to exchange competence requires a dynamic structural excursion that removes H-bond protection and allows exposure to solvent HX catalyst. The detailed data often make clear the nature of the dynamic excursion required. These range from whole molecule unfolding, through smaller cooperative unfolding reactions of secondary structural elements, and down to local fluctuations that involve as little as a single peptide group or side chain or water molecule. The particular motion that dominates the exchange of any hydrogen is the one that allows the fastest HX rate. The motion and the rate it produces are determined by surrounding structure and not by nearness to solvent or the strength of the protecting H-bond itself or its acceptor type (main chain, side chain, structurally bound water). Many of these motions occur over time scales that are appropriate for biochemical function. Published by Wiley-Blackwell. © 2012 The Protein Society.

Jo J.,University of California at Santa Barbara | Pouliot J.-R.,Laval University | Wynands D.,University of California at Santa Barbara | Collins S.D.,University of California at Santa Barbara | And 6 more authors.
Advanced Materials | Year: 2013

Power conversion efficiency up to 8.6% is achieved for a solution-processed tandem solar cell based on a diketopyrrolopyrrole-containing polymer as the low-bandgap material after using a thin polyelectrolyte layer to modify the electron-transport ZnO layers, indicating that interfacial engineering is a useful approach to further enhancing the efficiency of tandem organic solar cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pak Y.,Pusan National University | Zhang Y.,U.S. National Cancer Institute | Pastan I.,U.S. National Cancer Institute | Lee B.,U.S. National Cancer Institute | Lee B.,U.S. National Institutes of Health
Cancer Research | Year: 2012

Recombinant immunotoxins (RIT) are targeted anticancer agents that are composed of a targeting antibody fragment and a protein toxin fragment. SS1P is a RIT that targets mesothelin on the surface of cancer cells and is being evaluated in patients with mesothelioma. Mesothelin, like many other target antigens, is shed from the cell surface. However, whether antigen shedding positively or negatively affects the delivery of RIT remains unknown. In this study, we used experimental data with SS1P to develop a mathematical model that describes the relationship between tumor volume changes and the dose level of the administered RIT, while accounting for the potential effects of antigen shedding. ©2012 AACR.

Feldman T.,Sloan Kettering Cancer Center | Kabaleeswaran V.,New York Medical College | Jang S.B.,New York Medical College | Jang S.B.,Pusan National University | And 4 more authors.
Molecular Cell | Year: 2012

Caspase inhibition is a promising approach for treating multiple diseases. Using a reconstituted assay and high-throughput screening, we identified a group of nonpeptide caspase inhibitors. These inhibitors share common chemical scaffolds, suggesting the same mechanism of action. They can inhibit apoptosis in various cell types induced by multiple stimuli; they can also inhibit caspase-1-mediated interleukin generation in macrophages, indicating potential anti-inflammatory application. While these compounds inhibit all the tested caspases, kinetic analysis indicates they do not compete for the catalytic sites of the enzymes. The cocrystal structure of one of these compounds with caspase-7 reveals that it binds to the dimerization interface of the caspase, another common structural element shared by all active caspases. Consistently, biochemical analysis demonstrates that the compound abates caspase-8 dimerization. Based on these kinetic, biochemical, and structural analyses, we suggest that these compounds are allosteric caspase inhibitors that function through binding to the dimerization interface of caspases. © 2012 Elsevier Inc.

Kim J.-H.,Pusan National University | Song C.E.,KAIST | Kim B.,Korea Institute of Science and Technology | Kang I.-N.,Catholic University of Korea | And 2 more authors.
Chemistry of Materials | Year: 2014

We designed and synthetized a new poly{4,8-bis((2-ethylhexyl)thieno[3,2-b] thiophene)-benzo[1,2-b:4,5-b′]dithiophene-alt-2-ethylhexyl-4, 6-dibromo-3-fluorothieno[3,4-b]thiophene-2-carboxylate} (PTTBDT-FTT) comprising bis(2-ethylhexylthieno[3,2-b]thiophenylbenzo[1,2-b:4,5-b′]dithiophene (TTBDT) and 2-ethylhexyl 3-fluorothieno[3,4-b]thiophene-2-carboxylate (FTT). The optical bandgap of PTTBDT-FTT was 1.55 eV. The energy levels of the highest occupied and lowest unoccupied molecular orbitals of PTTBDT-FTT were -5.31 and -3.73 eV, respectively. Two-dimensional grazing-incidence X-ray scattering measurements showed that the film's PTTBDT-FTT chains are predominantly arranged with a face-on orientation with respect to the substrate, with strong π-π stacking. An organic thin-film transistor fabricated using PTTBDT-FTT as the active semiconductor showed high hole mobility of 2.1 × 10-2 cm2/(V·s). Single-junction bulk heterojunction photovoltaic cells with the configuration ITO/PEDOT:PSS/PTTBDT-FTT:PC71BM/Ca/Al were fabricated, which showed a maximum power conversion efficiency (PCE) of 7.44%. Inverted photovoltaic cells with the structure ITO/PEIE/PTTBDT-FTT: PC71BM/MoO3/Ag were also fabricated, with a maximum PCE of 7.71%. A tandem photovoltaic device comprising the inverted PTTBDT-FTT:PC 71BM cell and a P3HT:ICBA-based cell as the top and bottom cell components, respectively, showed a maximum PCE of 8.66%. This work demonstrated that the newly developed PTTBDT-FTT polymer was very promising for applications in both single and tandem solar cells. Furthermore, this work highlighted the fact that an extended π-system in the electron-donor moiety in low bandgap polymers is crucial for improving polymer solar cells. © 2013 American Chemical Society.

Skinner J.J.,University of Pennsylvania | Skinner J.J.,University of Chicago | Lim W.K.,Pusan National University | Bedard S.,University of Pennsylvania | And 2 more authors.
Protein Science | Year: 2012

To investigate the determinants of protein hydrogen exchange (HX), HX rates of most of the backbone amide hydrogens of Staphylococcal nuclease were measured by NMR methods. A modified analysis was used to improve accuracy for the faster hydrogens. HX rates of both near surface and well buried hydrogens are spread over more than 7 orders of magnitude. These results were compared with previous hypotheses for HX rate determination. Contrary to a common assumption, proximity to the surface of the native protein does not usually produce fast exchange. The slow HX rates for unprotected surface hydrogens are not well explained by local electrostatic field. The ability of buried hydrogens to exchange is not explained by a solvent penetration mechanism. The exchange rates of structurally protected hydrogens are not well predicted by algorithms that depend only on local interactions or only on transient unfolding reactions. These observations identify some of the present difficulties of HX rate prediction and suggest the need for returning to a detailed hydrogen by hydrogen analysis to examine the bases of structure-rate relationships, as described in the companion paper (Skinner et al., Protein Sci 2012;21:996-1005). Published by Wiley-Blackwell. © 2012 The Protein Society.

Choi H.,Ulsan National Institute of Science and Technology | Ko S.-J.,Ulsan National Institute of Science and Technology | Choi Y.,Ulsan National Institute of Science and Technology | Joo P.,Ulsan National Institute of Science and Technology | And 10 more authors.
Nature Photonics | Year: 2013

The coupling of surface plasmons and excitons in organic materials can improve the performance of organic optoelectronic devices. Here, we prepare carbon-dot-supported silver nanoparticles (CD-Ag nanoparticles) using the carbon dots both as a reducing agent and a template to fabricate solution-processable polymer light-emitting diodes and polymer solar cells. The surface plasmon resonance effect of CD-Ag nanoparticles allows significant radiative emission and additional light absorption, leading to remarkably enhanced current efficiency of 27.16 cd A -1 and a luminous efficiency of 18.54 lm W -1 in polymer light-emitting diodes as well as a power conversion efficiency of 8.31% and an internal quantum efficiency of 99% in polymer solar cells compared with control devices (current efficiency = 11.65 cd A -1 and luminous efficiency = 6.33 lm W -1 in polymer light-emitting diodes; power conversion efficiency = 7.53% and internal quantum efficiency = 91% in polymer solar cells). These results demonstrate that CD-Ag nanoparticles constitute a versatile and effective route for achieving high-performance polymer optoelectronic devices. © 2013 Macmillan Publishers Limited. All rights reserved.

Choi Y.,Ulsan National Institute of Science and Technology | Bae H.S.,Pusan National University | Seo E.,Ulsan National Institute of Science and Technology | Jang S.,Pusan National University | And 2 more authors.
Journal of Materials Chemistry | Year: 2011

We demonstrate a simple, one-step synthesis of hybrid gold nanoparticle-graphene oxide nanosheets (Au-GO) through electrostatic self-assembly. This method affords a facile means of controlling the effective concentration of the active Au nanoparticles on the graphene sheets, but also offers the necessary stability of the resulting Au-GO nanostructure for catalytic transformation. Furthermore, this hybrid Au-GO is successfully employed in the catalytic reduction of a series of nitroarenes with high catalytic activity. Through careful investigation of the catalyst, we find the synergistic catalytic effect of Au nanoparticles and GO, further highlighting the significance of hybrid Au-GO nanostructure. Considering the wide potential applications of a two-dimensional graphene sheet as a host material for a variety of nanoparticles, the approach developed here may lead to new possibilities for the fabrication of hybrid nanoparticle-graphene nanosheet structures endowed with multiple functionalities. © 2011 The Royal Society of Chemistry.

Choi H.,Ulsan National Institute of Science and Technology | Park J.S.,Korea Advanced Institute of Science and Technology | Jeong E.,Pusan National University | Kim G.-H.,Ulsan National Institute of Science and Technology | And 5 more authors.
Advanced Materials | Year: 2011

Interface engineering by combination of TiOx and a conjugated polyelectrolyte as an electron transport layer modifies the electrical contact between a metal electrode and an organic active layer with well-aligned frontier orbital energy levels for efficient charge transport. This results in remarkable improvements in the device performance of inverted polymer solar cells and polymer light-emitting diodes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim D.H.,Daegu Gyeongbuk Institute of Science and Technology | Kim C.,Daegu Gyeongbuk Institute of Science and Technology | Kim C.,Pohang University of Science and Technology | Heo S.H.,Daegu Gyeongbuk Institute of Science and Technology | And 2 more authors.
Acta Materialia | Year: 2011

The influence of the starting powders' morphology on the thermoelectric anisotropy of Bi-Te-based thermoelectric materials that are fabricated by spark plasma sintering has been investigated. Starting powders with three types of morphologies are prepared through a chemical reaction method (nano-sized particles with a spherical shape), a conventional pulverization method (flake-like shape) and a gas atomizing method (spherical shape). The thermoelectric anisotropy of each sintered body is determined by measuring the electrical resistivity and thermal conductivity in both the parallel and perpendicular directions to the spark plasma sintering pressing direction. The p-type Bi0.5Sb1.5Te3.0-sintered body that is composed of the spherically shaped powder has isotropic thermoelectric properties, while the same material composed of the flake-like powder shows anisotropic behavior. The n-type Bi2Te3 sintered body has a relatively small anisotropy when it is composed from the spherically shaped powder. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Lee S.-Y.,Ulsan National Institute of Science and Technology | Choi K.-H.,Ulsan National Institute of Science and Technology | Choi W.-S.,Pusan National University | Kwon Y.H.,LG Corp | And 3 more authors.
Energy and Environmental Science | Year: 2013

The unending demand for portable, flexible, and even wearable electronic devices that have an aesthetic appeal and unique functionality stimulates the development of advanced power sources that have excellent electrochemical performance and, more importantly, shape versatility. The challenges in the fabrication of next-generation flexible power sources mainly arise from their limited form factors, which prevent their facile integration into differently shaped electronic devices, and from the lack of reliable electrochemical materials that exhibit optimized attributes and suitable processability. This review describes the technological innovations and challenges associated with flexible energy storage and conversion systems such as lithium-ion batteries and supercapacitors, along with an overview of the progress in flexible proton exchange membrane fuel cells (PEMFCs) and solar cells. In particular, recently highlighted cable-type flexible batteries with extreme omni-directional flexibility are comprehensively discussed. © 2013 The Royal Society of Chemistry.

Kang H.,KAIST | Uddin M.A.,Pusan National University | Lee C.,KAIST | Kim K.-H.,KAIST | And 6 more authors.
Journal of the American Chemical Society | Year: 2015

The molecular weight of a conjugated polymer is one of the key factors determining the electrical, morphological, and mechanical properties as well as its solubility in organic solvents and miscibility with other polymers. In this study, a series of semicrystalline poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) polymers with different number-average molecular weights (Mns) (PPDT2FBTL, Mn = 12 kg/mol; PPDT2FBTM, Mn= 24 kg/mol; PPDT2FBTH, Mn= 40 kg/mol) were synthesized, and their photovoltaic properties as electron donors for all-polymer solar cells (all-PSCs) with poly[[N,N-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5-(2,2-bithiophene)] (P(NDI2OD-T2)) acceptor were studied. The Mn effect of PPDT2FBT on the structural, morphological, electrical, and photovoltaic properties was systematically investigated. In particular, tuning the Mn induced dramatic effects on the aggregation behaviors of the polymers and their bulk heterojunction morphology of all-PSCs, which was thoroughly examined by grazing incident X-ray scattering, resonant soft X-ray scattering, and other microscopy measurements. High Mn PPDT2FBTH promoted a strong "face-on" geometry in the blend film, suppressed the formation of an excessively large crystalline domain, and facilitated molecularly intermixed phases with P(NDI2OD-T2). Therefore, the optimized all-PSCs based on PPDT2FBTH/P(NDI2OD-T2) showed substantially higher hole and electron mobilities than those of PPDT2FBTL/P(NDI2OD-T2), leading to a power conversion efficiency exceeding 5%, which is one of the highest values for all-PSCs reported thus far. © 2015 American Chemical Society.

Behera S.K.,The Clean Tech Center | Kim H.W.,University of Ulsan | Oh J.-E.,Pusan National University | Park H.-S.,The Clean Tech Center | Park H.-S.,University of Ulsan
Science of the Total Environment | Year: 2011

Occurrence and removal efficiencies of 20 pharmaceuticals and personal care products (PPCPs) including antibiotics, hormones, and several other miscellaneous pharmaceuticals (analgesics, antiepileptics, antilipidemics, antihypertensives, antiseptics, and stimulants) were investigated in five wastewater treatment plants (WWTPs) of Ulsan, the largest industrial city of Korea. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The results showed that acetaminophen, atenolol and lincomycin were the main individual pollutants usually found in concentrations over 10 μg/L in the sewage influent. In the WWTPs, the concentrations of analgesic acetaminophen, stimulant caffeine, hormones estriol and estradiol decreased by over 99%. On the contrary, the antibiotic sulfamethazine, the antihypertensive metoprolol, and the antiepileptic carbamazepine exhibited removal efficiencies below 30%. Particularly, removal of antibiotics was observed to vary between -11.2 and 69%. In the primary treatment (physico-chemical processes), the removal of pharmaceuticals was insignificant (up to 28%) and removal of majority of the pharmaceuticals occurred during the secondary treatment (biological processes). The compounds lincomycin, carbamazepine, atenolol, metoprolol, and triclosan showed better removal in WWTPs employing modified activated sludge process with co-existence of anoxic-oxic condition. Further investigation into the design and operational aspects of the biological processes is warranted for the efficient removal of PPCPs, particularly antibiotics, to secure healthy water resource in the receiving downstream, thereby ensuring a sustainable water cycle management. © 2011.

Lee J.-E.,Case Western Reserve University | Sun Y.,Pusan National University | Gjorstrup P.,Pusan National University | Pearlman E.,Resolvyx Pharmaceuticals
Investigative Ophthalmology and Visual Science | Year: 2015

PURPOSE. To investigate the role of the lipid mediator, resolvin E1 (RvE1), in corneal inflammation. METHODS. The effect of RvE1 on stimulated human corneal epithelial cells (HCECs) and neutrophils, and mouse macrophage was assessed. C57BL/6 mouse corneas were abraded and treated with RvE1 either before or after stimulation with lipopolysaccharide (LPS) and antibiotic-killed Pseudomonas aeruginosa and Staphylococcus aureus. The levels of CXC chemokines in the cornea were quantified, and the presence of neutrophils in corneal infiltrates was detected by immunohistochemistry and by in vivo confocal microscopy. The effect of RvE1 on apoptosis in the corneal epithelium was assessed using the TUNEL assay. RESULTS. RvE1 significantly inhibited cytokine production in HCECs and neutrophils, and mouse macrophages and cornea. The development of corneal infiltrates, specifically neutrophils, in response to stimulation with LPS, P. aeruginosa, and S. aureus was also significantly reduced. There was no apoptotic effect of RvE1 on mouse corneal epithelial cells. CONCLUSIONS. RvE1 inhibits corneal inflammation induced by LPS, Gram negative (P. aeruginosa) and Gram positive (S. aureus) bacteria. These findings indicate that RvE1 as a potential anti-inflammatory therapy for patients with corneal inflammation and also, when given together with antibiotics, for bacterial keratitis. © 2015 The Association for Research in Vision and Ophthalmology, Inc.

Kim Y.S.,Brigham and Women's Hospital | Guevara J.P.,Children's Hospital of Philadelphia | Kim K.M.,Pusan National University | Choi H.K.,University of British Columbia | And 2 more authors.
Arthritis Care and Research | Year: 2010

Objective. The role of serum uric acid as an independent risk factor for cardiovascular disease remains unclear, although hyperuricemia is associated with cardiovascular disease such as coronary heart disease (CHD), stroke, and hypertension. Methods. A systematic review and meta-analysis using a random-effects model was conducted to determine the risk of CHD associated with hyperuricemia in adults. Studies of hyperuricemia and CHD were identified by searching major electronic databases using the medical subject headings and keywords without language restriction (through February 2009). Only prospective cohort studies were included if they had data on CHD incidences or mortalities related to serum uric acid levels in adults. Results. Twenty-six eligible studies of 402,997 adults were identified. Hyperuricemia was associated with an increased risk of CHD incidence (unadjusted risk ratio [RR] 1.34, 95% confidence interval [95% CI] 1.19-1.49) and mortality (unadjusted RR 1.46, 95% CI 1.20-1.73). When adjusted for potential confounding, the pooled RR was 1.09 (95% CI 1.03-1.16) for CHD incidence and 1.16 (95% CI 1.01-1.30) for CHD mortality. For each increase of 1 mg/dl in uric acid level, the pooled multivariate RR for CHD mortality was 1.12 (95% CI 1.05-1.19). Subgroup analyses showed no significant association between hyperuricemia and CHD incidence/mortality in men, but an increased risk for CHD mortality in women (RR 1.67, 95% CI 1.30-2.04). Conclusion. Hyperuricemia may marginally increase the risk of CHD events, independently of traditional CHD risk factors. A more pronounced increased risk for CHD mortality in women should be investigated in future research. © 2010, American College of Rheumatology.

Zang S.-L.,Xi'an Jiaotong University | Lee M.-G.,Pohang University of Science and Technology | Sun L.,General Motors | Kim J.H.,Pusan National University
International Journal of Plasticity | Year: 2014

In this paper, a novel approach is proposed to measure the Bauschinger effect, transient behavior and permanent softening of metallic sheet subjected to reverse loading. The hardening parameters related to the Bauschinger effect, transient behavior and permanent softening are optimized from the springback profiles of three-point bending tests with pre-strained sheets. Taking the dual phase steel sheet DP780 as an example, its Bauschinger effect, transient behavior and permanent softening determined from the new approach are compared with those of the cyclic simple shear method. Finite element simulations are also performed for three-point bending and U-draw/bending of base (as-received) and pre-strained DP780 steel sheets to validate the suggested approach. The results show that the aforementioned hardening behavior determined from the new approach shows good agreements with those of cyclic simple shear tests. Moreover, reasonable springback predictions for three-point bending and U-draw/bending tests are obtained as well. In particular, the proposed approach is quite suitable for the industrial applications because only uni-axial tension and three-point bending tests are required. © 2014 Elsevier B.V. All rights reserved.

Moon Y.,Pusan National University | Moon Y.,Immunoregulatory Therapeutics Group in Brain Busan 21 Project
Mediators of Inflammation | Year: 2014

Ribosomal inactivation damages 28S ribosomal RNA by interfering with its functioning during gene translation, leading to stress responses linked to a variety of inflammatory disease processes. Although the primary effect of ribosomal inactivation in cells is the functional inhibition of global protein synthesis, early responsive gene products including proinflammatory cytokines are exclusively induced by toxic stress in highly dividing tissues such as lymphoid tissue and epithelia. In the present study, ribosomal inactivation-related modulation of cytokine production was reviewed in leukocyte and epithelial pathogenesis models to characterize mechanistic evidence of ribosome-derived cytokine induction and its implications for potent therapeutic targets of mucosal and systemic inflammatory illness, particularly those triggered by organellar dysfunctions. © 2014 Yuseok Moon.

Kim H.-J.,Asia Pacific Economic Corporation Climate Center | Ahn J.-B.,Pusan National University
Journal of Climate | Year: 2015

This study verifies the impact of improved ocean initial conditions on the Arctic Oscillation (AO) forecast skill by assessing the one-month lead predictability of boreal winter AO using the Pusan National University (PNU) coupled general circulation model (CGCM). Hindcast experiments were performed on two versions of the model, one does not use assimilated ocean initial data (V1.0) and one does (V1.1), and the results were comparatively analyzed. The forecast skill of V1.1 was superior to that of V1.0 in terms of the correlation coefficient between the predicted and observed AO indices. In the regression analysis, V1.1 showed more realistic spatial similarities than V1.0 did in predicted sea surface temperature and atmospheric circulation fields. The authors suggest the relative importance of the contribution of the ocean initial condition to the AO forecast skill was because the ocean data assimilation increased the predictability of the AO, to some extent, through the improved interaction between tropical forcing induced by realistic sea surface temperature (SST) and atmospheric circulation. In V1.1, as in the observation, the cold equatorial Pacific SST anomalies generated the weakened tropical convection and Hadley circulation over the Pacific, resulting in a decelerated subtropical jet and accelerated polar front jet in the extratropics. The intensified polar front jet implies a stronger stratospheric polar vortex relevant to the positive AO phase; hence, surface manifestations of the reflected positive AO phase were then induced through the downward propagation of the stratospheric polar vortex. The results suggest that properly assimilated initial ocean conditions might contribute to improve the predictability of global oscillations, such as the AO, through large-scale tropical ocean-atmosphere interaction. © 2015 American Meteorological Society.

Choi K.-Y.,Asia Pacific Center for Theoretical Physics | Choi K.-Y.,Pohang University of Science and Technology | Kyae B.,Pusan National University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We propose an inflationary model ("natural hybrid model"), which combines the supersymmetric hybrid model and the natural inflation model to achieve the spectral index of 0.96, and the axion decay constant smaller than the Planck scale, f≪MP. By introducing both U(1)R and a shift symmetry and employing the minimal Kähler potential, the eta-problem can be still avoided. The two inflaton fields in this model can admit large non-Gaussianity. © 2011 Elsevier B.V.

Selvaraj M.,Pusan National University | Sinha P.K.,Bhabha Atomic Research Center
New Journal of Chemistry | Year: 2010

Two-dimensional SnSBA-15(CVD) catalyst was synthesized by the chemical vapor deposition (CVD) method using calcined SBA-15 with anhydrous tin(iv) chloride. For comparison studies, two mesoporous tin silicate catalysts, Sn/SBA-15(SC) and Sn/SBA-15(SA) were synthesized under the incipient wetness impregnation (IWI) method using calcined SBA-15 with different tin sources. SnMCM-41(40) was also synthesized by basic hydrothermal conditions. The synthesized mesoporous catalysts were characterized by ICP-AES, XRD, N 2 adsorption, UV vis DRS, 29Si MAS NMR, FE-SEM and TEM for the proof of standard mesoporous catalysts with nature of tin on the silica pore walls. For highly selective synthesis of nopol (N-OH), the Prins condensation of β-pinene (PE) with paraformaldehyde (PF-CHO) was performed over different mesoporous catalysts such as SiSBA-15, SnSBA-15(CVD), Sn/SBA-15(SC), SnSBA-15(SA) and SnMCM-41(40), and it was conducted using a variety of optimal parameters such as amount of catalyst, reaction time, reaction temperature, ratios of reactant (PE/PF-CHO), solvents and recycles. In addition, SnSBA-15(CVD) was used in the Prins condensation of PE with PF-CHO in the presence of propyl cyanide (PrCN) with water to investigate its catalytic activity. On the basis of all catalytic results, SnSBA-15(CVD) is found to be a highly active, water-resistant and recyclable heterogeneous catalyst for selective synthesis of N-OH. © 2010 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Choi K.-Y.,Asia Pacific Center for Theoretical Physics | Choi K.-Y.,Pohang University of Science and Technology | Kim S.A.,Asia Pacific Center for Theoretical Physics | Kyae B.,Pusan National University
Nuclear Physics B | Year: 2012

We study the generation of the primordial curvature perturbation in multi-field inflation. Considering both the evolution of the perturbation during inflation and the effects generated at the end of inflation, we present a general formula for the curvature perturbation. We provide the analytic expressions of the power spectrum, spectral tilt and non-Gaussianity for the separable potentials of two inflaton scalars, and apply them to some specific models. © 2012 Elsevier B.V.

Park E.,Pusan National University | Na H.S.,Pusan National University | Song Y.-R.,Pusan National University | Shin S.Y.,Pohang University of Science and Technology | And 2 more authors.
Infection and Immunity | Year: 2014

Porphyromonas gingivalis, a major periodontopathogen, is involved in the pathogenesis of periodontitis. Interleukin-1β (IL- 1β), a proinflammatory cytokine, regulates innate immune responses and is critical for the host defense against bacterial infection. However, excessive IL-1β is linked to periodontal destruction. IL-1β synthesis, maturation, and secretion are tightly regulated by Toll-like receptor (TLR) signaling and inflammasome activation. We found much higher levels of inflammasome components in the gingival tissues from patients with chronic periodontitis than in those from healthy controls. To investigate the molecular mechanisms by which P. gingivalis infection causes IL-1β secretion, we examined the characteristics of P. gingivalis- induced signaling in differentiated THP-1 cells. We found that P. gingivalis induces IL-1β secretion and inflammatory cell death via caspase-1 activation. We also found that P. gingivalis-induced IL-1β secretion and pyroptic cell death required both NLRP3 and AIM2 inflammasome activation. The activation of the NLRP3 inflammasome was mediated by ATP release, the P2X7 receptor, and lysosomal damage. In addition, we found that the priming signal via TLR2 and TLR4 activation precedes P. gingivalis- induced IL-1β release. Our study provides novel insight into the innate immune response against P. gingivalis infection which could potentially be used for the prevention and therapy of periodontitis. © 2014, American Society for Microbiology.

Kang K.H.,Pohang University of Science and Technology | Lim H.C.,Pusan National University | Lee H.W.,Pohang University of Science and Technology | Lee S.J.,Pohang University of Science and Technology
Physics of Fluids | Year: 2013

Inside evaporating two-component sessile droplets, a family of the Rayleigh convection exists, driven by salinity gradient formed by evaporation of solvent and solute. In this work, the characteristic of the flow inside an axisymmetric droplet is investigated. A stretched coordinate system is employed to account for the effect of boundary movement. A scaling analysis shows that the flow velocity is proportional to the (salinity) Rayleigh number (Ras) at the small-Rayleigh-number limit. A numerical analysis for a hemispherical droplet exhibits the flow velocity is proportional to the non-dimensional number Ras1/2, at high Rayleigh numbers. A self-similar condition is established for the concentration field irrespective of the Rayleigh numbers after a moderate time, and the flow field is invariant with time at this stage. The scaling relation for the high Rayleigh numbers is verified experimentally by using aqueous NaCl droplets. © 2013 American Institute of Physics.

Najafpour M.M.,Institute for Advanced Studies in Basic Sciences | Rahimi F.,Institute for Advanced Studies in Basic Sciences | Aro E.-M.,University of Turku | Lee C.-H.,Pusan National University | Allakhverdiev S.I.,RAS Institute of Basic Biological Problems
Journal of the Royal Society Interface | Year: 2012

There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese-calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups. © 2012 The Royal Society.

Nguyen T.L.,Pusan National University | Choi H.,Ulsan National Institute of Science and Technology | Ko S.-J.,Ulsan National Institute of Science and Technology | Uddin M.A.,Pusan National University | And 8 more authors.
Energy and Environmental Science | Year: 2014

We report a series of semi-crystalline, low band gap (LBG) polymers and demonstrate the fabrication of highly efficient polymer solar cells (PSCs) in a thick single-cell architecture. The devices achieve a power conversion efficiency (PCE) of over 7% without any post-treatment (annealing, solvent additive, etc.) and outstanding long-term thermal stability for 200 h at 130 °C. These excellent characteristics are closely related to the molecular structures where intra- and/or intermolecular noncovalent hydrogen bonds and dipole-dipole interactions assure strong interchain interactions without losing solution processability. The semi-crystalline polymers form a well-distributed nano-fibrillar networked morphology with PC70BM with balanced hole and electron mobilities (a h/e mobility ratio of 1-2) and tight interchain packing (a π-π stacking distance of 3.57-3.59 Å) in the blend films. Furthermore, the device optimization with a processing additive and methanol treatment improves efficiencies up to 9.39% in a ∼300 nm thick conventional single-cell device structure. The thick active layer in the PPDT2FBT:PC 70BM device attenuates incident light almost completely without damage in the fill factor (0.71-0.73), showing a high short-circuit current density of 15.7-16.3 mA cm-2. Notably, PPDT2FBT showed negligible changes in the carrier mobility even at ∼1 μm film thickness. This journal is © the Partner Organisations 2014.

Koolen J.H.,Pohang University of Science and Technology | Bang S.,Pusan National University
Journal of Combinatorial Theory. Series B | Year: 2010

A non-complete geometric distance-regular graph is the point graph of a partial linear space in which the set of lines is a set of Delsarte cliques. In this paper, we prove that for a fixed integer m≥2, there are only finitely many non-geometric distance-regular graphs with smallest eigenvalue at least - m, diameter at least three and intersection number c2≥2. © 2010 Elsevier Inc.

Lee D.Y.,Pusan National University | Lee D.Y.,Korea Basic Science Institute | Kwon C.,Myongji University | Pak H.K.,Korea Basic Science Institute | Pak H.K.,Ulsan National Institute of Science and Technology
Physical Review Letters | Year: 2015

We investigate the motion of a colloidal particle driven out of equilibrium by a time-varying stiffness of the optical trap that produces persistent nonequilibrium work. Measurements of work production for repeated cycles composed of the compression and expansion processes for the optical potential show huge fluctuations due to thermal motion. Using a precise technique to modulate the stiffness in time, we accurately estimate the probability distributions of work produced for the compression and expansion processes. We confirm the fluctuation theorem from the ratio of the two distributions. We also show that the average values of work for the two processes comply with the Jarzynski equality. This system has an analogy with a gas in a breathing soft wall. We discuss about its applicability to a heat engine and an information engine operated by feedback control. © 2015 American Physical Society.

Lee W.,Pusan National University | Choi H.,Ulsan National Institute of Science and Technology | Hwang S.,Pusan National University | Kim J.Y.,Ulsan National Institute of Science and Technology | Woo H.Y.,Pusan National University
Chemistry - A European Journal | Year: 2012

A low-band-gap alternating copolymer, poly{5,6-bis(octyloxy)-4-(thiophen-2- yl)benzo[c]-1,2,5-thiadiazole} (PTBT), was synthesized and investigated for photovoltaic applications. PTBT showed a minimized torsion angle in its main backbone owing to the introduction of solubilizing octyloxy groups on the electron-poor benzothiadiazole unit, thereby resulting in pronounced intermolecular ordering and a deep level of the HOMO (-5.41 eV). By blending PTBT with [6,6]phenyl-C61-butyric acid methyl ester (PC 61BM), highly promising performance was achieved with power-conversion efficiencies (PCEs) of 5.9 and 5.3% for the conventional and inverted devices, respectively, under air mass 1.5 global (AM 1.5G, 100 mWcm -2) illumination. The open-circuit voltage (V OC≈0.85-0.87 V) is one of the highest values reported thus far for thiophene-based polymers (e.g., poly(3-hexylthiophene) V OC≈0.6 V). The inverted device also achieved a remarkable PCE compared to other devices based on low-band-gap polymers. Ideal film morphology with bicontinuous percolation pathways was expected from the atomic force microscopy (AFM) images, space-charge-limited current (SCLC) mobility, and selected-area electron-diffraction (SAED) measurements. This molecular design strategy is useful for achieving simple, processable, and planar donor-acceptor (D-A)-type low-band-gap polymers with a deep HOMO for applications in photovoltaic cells. A hard cell: A planar low-band-gap copolymer (PTBT) with high intermolecular ordering and a deep HOMO level was synthesized for use in photovoltaic cells. PTBT contained alternating thiophene and alkoxy-substituted benzothiadiazole groups. Both conventional- and inverted-type photovoltaic devices showed promising power-conversion efficiencies (5.9 and 5.3%, respectively). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shin M.,Hanbat National University | Ryu K.,Pusan National University | Jung M.,Ulsan National Institute of Science and Technology
Expert Systems with Applications | Year: 2012

Up-to-date market dynamics has been forcing manufacturing systems to adapt quickly and continuously to the ever-changing environment. Self-evolution of manufacturing systems means a continuous process of adapting to the environment on the basis of autonomous goal-formation and goal-oriented dynamic organization. This paper proposes a goal-regulation mechanism that applies a reinforcement learning approach, which is a principal working mechanism for autonomous goal-formation. Individual goals are regulated by a neural network-based fuzzy inference system, namely, a goal-regulation network (GRN) updated by a reinforcement signal from another neural network called goal-evaluation network (GEN). The GEN approximates the compatibility of goals with current environmental situation. In this paper, a production planning problem is also examined by a simulation study in order to validate the proposed goal regulation mechanism. © 2012 Elsevier Ltd. All rights reserved.

Bang I.C.,Ulsan National Institute of Science and Technology | Jeong J.H.,Pusan National University
Nuclear Engineering and Technology | Year: 2011

A variety of Generation III/III+ water-cooled reactor designs featuring enhanced safety and improved economics are being proposed by nuclear power industries around the world in efforts to solve the future energy supply shortfall. Thermal-hydraulics is recognized as a key scientific subject in the development of innovative reactor systems. Phase change by boiling and condensation in the reverse process is a highly efficient heat transport mechanism that accommodates large heat fluxes with relatively small driving temperature differences. This mode of heat transfer is encountered in a wide spectrum of nuclear systems.and thus it is necessary to determine the thermal limit of water-cooled nuclear energy conversion in terms of economic and safety. Such applications are being advanced with the introduction of new technologies such as nanotechnology. Here, we investigated newly-introduced nanotechnologies relevant to boiling and condensation in general engineering applications. We also evaluated the potential linkage between such new advancements and nuclear applications in terms of advanced nuclear thermal-hydraulics.

Pusan National University and S&G Biotech Inc | Date: 2016-03-16

A cardiac valve fixing device of the present invention comprises: a first structure, which continuously comes into contact with the lower surface of at least one cardiac valve; a second structure, which is connected to the first structure and continuously comes into contact with the upper surface of the cardiac valve; and a fixing barb, which is equipped in at least one of the first structure and the second structure and protrusively formed to the direction of the cardiac valve so as to be inserted into the cardiac valve. Accordingly, the cardiac valve fixing device of the present invention stably fixes the cardiac valve.

Pusan National University and S&G Biotech Inc. | Date: 2014-04-16

A cardiac valve fixing device of the present invention comprises: a first structure, which continuously comes into contact with the lower surface of at least one cardiac valve; a second structure, which is connected to the first structure and continuously comes into contact with the upper surface of the cardiac valve; and a fixing barb, which is equipped in at least one of the first structure and the second structure and protrusively formed to the direction of the cardiac valve so as to be inserted into the cardiac valve. Accordingly, the cardiac valve fixing device of the present invention stably fixes the cardiac valve.

Wagner M.H.,TU Berlin | Rolon-Garrido V.H.,TU Berlin | Hyun K.,Pusan National University | Wilhelm M.,Karlsruhe Institute of Technology
Journal of Rheology | Year: 2011

Studying the mechanical response of nearly monodisperse linear and comb polystyrene (PS) melts to medium amplitude oscillatory shear (MAOS), Hyun and Wilhelm [Macromolecules 42, 411 (2009)] identified two important scaling relations: (1) The relative intensity I3/1 of the third harmonic compared to the first harmonic scales with the strain amplitude according to γ0 2. Consequently, a new nonlinear coefficient Q I3/1 / γ0 2 as well as the so-called intrinsic nonlinearity Q0 lim γ0→0 Q was introduced. (2) In the terminal relaxation regime, the intrinsic nonlinearity Q0 (ω) scales with ω2 and was found to be a very sensitive measure regarding molecular topology by identifying and separating relaxation processes in model branched polymers. A constitutive analysis based on a general single integral constitutive equation, which includes the Doi-Edwards model without (DE) and with (DE IA) independent alignment assumption as well as the molecular stress function (MSF) model, confirms both scaling relations. We show that the nonlinear viscoelastic moduli can be expressed as sums of their linear-viscolelastic counterparts at frequencies of ω, 2ω, and 3ω. The absolute value of Q 0 (ω) depends on the difference (α-Β) between the third order orientational effect (parameter α) according to the DE or DE IA model and the second order isotropic stretching effect (parameter Β) according to the MSF model. When comparing MAOS data to constitutive models, the apparent values of Q0 (ω) measured in parallel-plate geometry have to be rescaled in order to take the non-uniform shear deformation into account. Both the DE and DE IA models fail to describe the experimental data. The data of four linear PS melts are quantitatively described by the MSF model with nonlinear parameters α=5/21 (corresponding to the DE IA model) and Β=0.12 in the terminal relaxation regime. For the comb polymers, with the same orientational parameter of α=5/21, stretch parameters of Β=0.14 for a polymer with unentangled branches and of Β=0.18 for two polymers with entangled branches are found. However, the model predicts a plateau at the level of the maximum of the experimental data, while the experimental values of Q0 decrease with increasing frequency. For the comb polymers with entangled branches, a minimum in Q0 is observed, and a second increase of Q0 at higher frequencies, which correspond to the terminal relaxation times of the branches. Surprisingly, these features can be modeled quantitatively if only the terminal relaxation modes of the backbone and, if present, the branches are assumed to deforming non-affinely and responding to the nonlinearity. The shorter modes seem to be deforming affinely and are excited only in the regime of finite linear viscoelasticity. We are presently not aware of any molecular mechanism that could explain this behavior. © 2011 The Society of Rheology.

News Article | January 29, 2016
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The editors of Current Applied Physics have given their recommendations for articles recently published in the journal. Editor in Chief, Eun Kyung Suh, Professor at Chonbuk National University and Executive Editor, Sungkyun Park, from Pusan National University, have recommended the following titles, all of which are free to download: Structural, morphological, compositional, and optical properties of single step electrodeposited Cu2ZnSnS4 (CZTS) thin films for solar cell application (Volume 14, Issue 3, March 2014, Pages 254–258. Authors: Seul Gi Lee, Jongmin Kim, Huyn Suk Woo, Yongcheol Jo, A.I. Inamdar, S.M. Pawar, Hyung Sang Kim, Woong Jung, Hyun Sik Im) A new era for liquid crystal research: Applications of liquid crystals in soft matter nano-, bio- and microtechnology (Volume 12, Issue 6, November 2012, Pages 1387–1412. Authors: Jan P.F. Lagerwall, Giusy Scalia)

Park J.-W.,Pusan National University | Hwang S.-H.,Florida State University | Kim J.-M.,Pusan National University
IEEE Transactions on Industry Applications | Year: 2012

A new sensorless control algorithm for brushless dc motors (BLDCMs) is proposed in this paper. The torque constant of a BLDCM is used as a reference signal for position detection because it is constant during the entire speed range and can be estimated by calculating the ratio of the back electromotive force (EMF) to the rotor speed. By using both a disturbance observer and the torque constant estimation error, the rotor speed can be obtained. The back EMF can be easily obtained from the voltage equation of the BLDCM. The estimated back EMF decreases simultaneously with the estimated torque constant at the commutation point. By using this phenomenon, the commutation of the phase currents can be done automatically at the drop point of the estimated torque constant. Unlike conventional back-EMF-based methods, the proposed method provides highly accurate sensorless operation even under low speeds because only the drop of the torque constant is used for position detection and current commutation. Therefore, the position accuracy is not affected by the electric parameter errors of the BLDCM. Also, this algorithm does not require an additional hardware circuit for position detection. The validity of the proposed algorithm is verified through several experiments. © 2011 IEEE.

Choi Y.J.,University of California at Los Angeles | Jung J.,University of California at Los Angeles | Chung H.K.,University of California at Los Angeles | Im E.,Pusan National University | Rhee S.H.,University of California at Los Angeles
FASEB Journal | Year: 2013

Defective IL-10 allele is a risk factor for intestinal inflammation. Indeed, IL-10-/- mice are predisposed to spontaneous colitis in the presence of intestinal microbiota, indicating that microbial factors contribute to developing intestinal inflammation. By recognizing flagellin, TLR5 plays a quintessential role in microbial recognition in intestinal epithelial cells. Here, we treated flagellin (1.0 μg/mouse/d) in mouse colon and found that it elicited colonic inflammation in IL-10-/- mice, characterized with tissue hypertrophy, inflamed epithelium, and enhanced cytokine production in the colon (MPO, KC, IL-6; ≥2-fold; P < 0.05). These inflammatory effects were dramatically inhibited in TLR5-/-;IL-10-/- mice. Intestinal epithelium specific PTEN deletion significantly attenuated flagellin-promoted colonic inflammation in IL-10-/- mice. As a molecular mechanism that PTEN deletion inhibited TLR5-elicited responses, we hypothesized that PTEN regulated TLR5-induced responses by controlling the involvement of Mal in TLR5 engagement. Mal interacted with TLR5 on flagellin, and Mal deficiency inhibited flagellin-induced responses in intestinal epithelial cells. Similarly, Mal-/-;IL-10-/- mice showed reduced flagellin-promoted responses. Furthermore, PTEN deletion disrupted Mal-TLR5 interaction, resulting in diminished TLR5-induced responses. PTEN deletion impeded Mal localization at the plasma membrane and suppressed Mal-TLR5 interaction. These results suggest that, by controlling Mal recruitment, PTEN regulates TLR5-induced inflammatory responses. © FASEB.

Higaki T.,Keio University | Jeong K.S.,Pusan National University | Kitajima N.,Asia Pacific Center for Theoretical Physics | Takahashi F.,Tohoku University | Takahashi F.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We argue that the QCD axion can arise from many aligned axions with decay constants much smaller than the conventional axion window. If the typical decay constant is of O(100) GeV to 1 TeV, one or more of the axions or saxions may account for the recently found diphoton excess at ~750 GeV. Our scenario predicts many axions and saxions coupled to gluons with decay constants of order the weak scale, and therefore many collider signatures by heavy axions and saxions will show up at different energy scales. In particular, if the inferred broad decay width is due to multiple axions or saxions, a non-trivial peak structure may become evident when more data is collected. We also discuss cosmological implications of the aligned QCD axion scenario. In the Appendix we give a possible UV completion and argue that the high quality of the Peccei-Quinn symmetry is naturally explained in our scenario. © 2016 Published by Elsevier B.V.

Im E.,Pusan National University | Jung J.,University of California at Los Angeles | Rhee S.H.,University of California at Los Angeles
Journal of Interferon and Cytokine Research | Year: 2012

The family of Interleukin-17 (IL-17) cytokine is the essential inflammatory mediator that influences the pathophysiology of various inflammatory diseases. Many studies focused on investigating the expression, signaling, and biological impacts of IL-17A and IL-17F, and the neutralization of these cytokines exhibited some promising results in clinical trials. In contrast, the expression resources and physiological relevance of IL-17C remained to be studied. In this study, through a microarray approach conducted with nontransformed human colonic epithelial cells (NCM460), we found that bacterial flagellin stimulation elicited potent IL-17C mRNA expression. We also confirmed that IL-17C protein production was strongly induced by flagellin in these cells. Flagellin-induced IL-17C expression was also observed in human colon adenocarcinoma cells such as DLD-1 and HT-29, indicating that IL-17C could be a signature inflammatory cytokine from intestinal epithelial cells in response to flagellin. Since inhibited in TLR5-, or MyD88- or TRIF-silenced cells, flagellin-induced IL-17C expression was specifically mediated by TLR5 and, subsequently, MyD88 and TRIF adaptor molecules. Furthermore, in line with inflammatory nature of IL-17, we found that IL-17C expression was substantially enhanced in the intestinal tissues from Ulcerative colitis patients. Given the facts that TLR5 is a key pattern recognition receptor which mediates microbial recognition in the intestinal epithelium and IL-17C turned out to be a unique member of the IL-17 family expressed in intestinal epithelial cells on TLR5 activation, our study may provide an important clue on understanding how intestinal microbes would contribute to an inflammatory program in the gut. © 2012, Mary Ann Liebert, Inc.

Hairil Mohd M.,Pusan National University | Hairil Mohd M.,University of Malaysia, Terengganu | Paik J.K.,Pusan National University
Corrosion Science | Year: 2013

One of the most challenging issues in the offshore oil and gas industry is corrosion assessment and management in subsea structures or equipment. The aim of this study was to investigate the corrosion progress characteristics of offshore oil well tubes used in the production of oil in deep water. A direct measurement database of corrosion damage in terms of pit depth with age (time) in offshore oil well tubes was collated. The corrosion data were statistically analysed to identify the probability density distribution of corrosion damage with time. An empirical formula to predict time-dependent corrosion damage in offshore oil well tubes is suggested based on the results of the statistical analysis. Given that there are few corrosion measurement databases of subsea equipment used for offshore oil and gas production in the literature, this study should prove useful for assessing and managing corrosion damage in deep water offshore oil well tubes, which are key pieces of equipment in offshore oil and gas production systems. © 2012 Elsevier Ltd.

Park J.K.,Pusan National University | Ondrusek B.A.,Florida State University | McQuade D.T.,Florida State University
Organic Letters | Year: 2012

The catalytic regioselective hydroboration of propargylic alcohols and ethers was investigated using NHC-CuCl. We observe that different NHCCuCl complexes catalyze hydroborations of propargylic substrates with opposite regioselectivity. A 6-NHC-CuCl complex provides R-selectivity whereas β-selectivity is achieved using a 5-NHC-CuCl complex. The reaction tolerates a wide range of functional groups. © 2012 American Chemical Society.

Shin J.,Pusan National University | Lee J.-W.,Pusan National University | Lee J.-W.,University of California at Los Angeles | Kim E.-A.,University of California at Los Angeles | Caprioli J.,University of California at Los Angeles
American Journal of Ophthalmology | Year: 2015

Purpose To evaluate the effects of corneal biomechanical properties on intraocular pressure (IOP) measured with the ICare, and to compare IOP readings obtained with ICare, Ocular Response Analyzer (ORA), and Goldmann applanation tonometry (GAT) in normal-tension glaucoma (NTG) and normal subjects. Design Prospective, cross-sectional, comparative study. Methods IOP was measured with ICare, ORA, and GAT. All subjects had corneal hysteresis (CH) and corneal resistance factor (CRF), which were measured with ORA; and central corneal thickness (CCT), axial length, spherical equivalent, and keratometry. Results This study enrolled 97 eyes of 97 NTG patients and 89 eyes of 89 normal subjects. CCT, CH, and CRF in NTG patients were significantly lower than those in normal subjects (P =.033, P =.006, and P =.003). The difference in IOP between techniques was highly significant in NTG patients (P <.001), while there was no significant difference in IOP values between techniques in normal controls (P =.931). ICare readings were significantly lower than corneal-compensated IOP in NTG patients (P =.014). CH and CRF were significantly associated with IOP measurements with ICare in NTG and normal subjects (P <.001). The greater difference between IOPcc and ICare in NTG patients was significantly influenced by the lower CH (P <.001). Conclusions Since ICare is a convenient way to measure IOP, ICare is a reasonable option as an alternative tonometer in NTG patients. However, the clinician must consider that the corneal biomechanical characteristics in NTG can cause ICare to underestimate IOP. © 2015 Elsevier Inc. ALL RIGHTS RESERVED.

Opalka S.M.,Florida State University | Opalka S.M.,Cornell University | Park J.K.,Florida State University | Park J.K.,Pusan National University | And 2 more authors.
Organic Letters | Year: 2013

It is demonstrated that homogeneous N-heterocyclic carbene-copper(I)- chloride complexes can be prepared continuously by flowing NHC precursors through a packed bed of solid Cu2O suspended in molecular sieves. The method enables the synthesis of a wide range of complexes including those that are challenging to prepare using standard approaches. Our strategy enables both sustained output of complex production for long-term catalytic reactions (greater than 5 h) and for generation of gram quantities for storage (greater than 1 g of complex in ∼16 min). © 2013 American Chemical Society.

Hwang S.-H.,Kyungnam University | Liu L.,Florida State University | Li H.,Florida State University | Kim J.-M.,Pusan National University
IEEE Transactions on Power Electronics | Year: 2012

This letter proposes a dc offset error compensation algorithm for synchronous reference frame phase-locked loop (PLL) in single-phase grid-connected converters. The errors generated from the grid voltage measurement circuits can be divided into dc offset and scaling errors. These errors may cause the undesirable periodic ripples with grid frequency in the synchronous reference frame PLL. As a result, the performance of the power conversion systems is degraded. In this letter, the effects of the dc offset and scaling errors are comprehensively analyzed based on the synchronous dq frame PLL. In particular, the dc offset error can be estimated and compensated by controlling the synchronous d -axis voltage in a PLL system to be zero. The proposed algorithm does not require any additional hardware and can be implemented by a simple proportional-integral controller and an integral operation. Experimental results are presented to demonstrate the effectiveness of the proposed dc offset error compensation algorithm. © 2012 IEEE.

Michaud J.,University of Connecticut Health Center | Im D.-S.,University of Connecticut Health Center | Im D.-S.,Pusan National University | Hla T.,University of Connecticut Health Center | Hla T.,Cornell University
Journal of Immunology | Year: 2010

Macrophage recruitment to sites of inflammation is an essential step in host defense. However, the mechanisms preventing excessive accumulation of macrophages remain relatively unknown. The lysophospholipid sphingosine 1-phosphate (S1P) promotes T and B cell egress from lymphoid organs by acting on S1P receptor 1 (S1P1R). More recently, S1P5R was shown to regulate NK cell mobilization during inflammation, raising the possibility that S1P regulates the trafficking of other leukocyte lineages. In this study, we show that S1P2R inhibits macrophage migration in vitro and that S1P2R-deficient mice have enhanced macrophage recruitment during thioglycollate peritonitis. We identify the signaling mechanisms used by S1P2R in macrophages, involving the second messenger cAMP and inhibition of Akt phosphorylation. In addition, we show that the phosphoinositide phosphatase and tensin homolog deleted on chromosome 10, which has been suggested to mediate S1P2R effects in other cell types, does not mediate S1P2R inhibition in macrophages. Our results suggest that S1P serves as a negative regulator of macrophage recruitment by inhibiting migration in these cells and identify an additional facet to the regulation of leukocyte trafficking by S1P. Copyright © 2010 by The American Association of Immunologists, Inc.

Huh J.-H.,University of California at Los Angeles | Kyae B.,Pusan National University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We propose a U(1)' mediated supersymmetry (SUSY) breaking, in which U(1)' is identified with U(1)B1+B2-2L1. The U(1)B1+B2-2L1 gauge symmetry, which is anomaly-free with the field contents of the minimal supersymmetric standard model, assigns ±1/3 charges to the first and second generations of the quarks, and 2 to the first generation of the leptons. As a result, the first two generations of squarks acquire masses of about 7 TeV, and the first generation of the sleptons do those of 40 TeV, respectively, in the presence of one or three pairs of extra vector-like matter {5,5}. Non-observation on extra colored particles below 1 TeV at the large hadron collider, and also the flavor violations such as μ-→e-γ are explained. By virtue of such a gauge symmetry, proton stability can be protected. The other squarks and sleptons as well as the gauginos can obtain masses of order 102-3 GeV through the conventional gravity or gauge mediated SUSY breaking mechanism. The relative light smuon/sneutrino and the neutralino/chargino could be responsible for the (g-2)μ deviated from the standard model prediction. The stop mass of ~500GeV relieves the fine-tuning problem in the Higgs sector. Two-loop effects by the relatively heavy sfermions can protect the smallness of the stop mass from the radiative correction by the heavy gluino (≳1TeV). Extra vector-like matter can enhance the radiative corrections to the Higgs mass up to 126 GeV, and induce the desired mixing among the chiral fermions after U(1)B1+B2-2L1 breaking. © 2013 Elsevier B.V.

Im E.,Pusan National University | Riegler F.M.,Medical University of Vienna | Pothoulakis C.,University of California at Los Angeles | Rhee S.H.,University of California at Los Angeles
American Journal of Physiology - Gastrointestinal and Liver Physiology | Year: 2012

Frequency of gram-negative bacteria is markedly enhanced in inflamed gut, leading to augmented LPS in the intestine. Although LPS in the intestine is considered harmless and, rather, provides protective effects against epithelial injury, it has been suggested that LPS causes intestinal inflammation, such as necrotizing enterocolitis. Therefore, direct effects of LPS in the intestine remain to be studied. In this study, we examine the effect of LPS in the colon of mice instilled with LPS by rectal enema. We found that augmented LPS on the luminal side of the colon elicited inflammation in the small intestine remotely, not in the colon; this inflammation was characterized by body weight loss, increased fluid secretion, enhanced inflammatory cytokine production, and epithelial damage. In contrast to the inflamed small intestine induced by colonic LPS, the colonic epithelium did not exhibit histological tissue damage or inflammatory lesions, although intracolonic LPS treatment elicited inflammatory cytokine gene expression in the colon tissues. Moreover, we found that intracolonic LPS treatment substantially decreased the frequency of immune-suppressive regulatory T cells (CD4 + /CD25 + and CD4 + /Foxp3 +). We were intrigued to find that LPS-promoted intestinal inflammation is exacerbated in immune modulator-impaired IL-10 -/- and Rag-1 -/- mice. In conclusion, our results provide evidence that elevated LPS in the colon is able to cause intestinal inflammation and, therefore, suggest a physiological explanation for the importance of maintaining the balance between gramnegative and gram-positive bacteria in the intestine to maintain homeostasis in the gut. © 2012 the American Physiological Society.

Sohn S.-J.,Climate Center | Ahn J.-B.,Pusan National University | Tam C.-Y.,City University of Hong Kong
Geophysical Research Letters | Year: 2013

The potential of using a dynamical-statistical method for long-lead drought prediction was investigated. In particular, the APEC Climate Center one-tier multimodel ensemble (MME) was downscaled for predicting the standardized precipitation evapotranspiration index (SPEI) over 60 stations in South Korea. SPEI depends on both precipitation and temperature, and can incorporate the effect of global warming on the balance between precipitation and evapotranspiration. It was found that the one-tier MME has difficulty in capturing the local temperature and rainfall variations over extratropical land areas, and has no skill in predicting SPEI during boreal winter and spring. On the other hand, temperature and precipitation predictions were substantially improved in the downscaled MME. In conjunction with variance inflation, downscaled MME can give reasonably skillful 6 month-lead forecasts of SPEI for the winter to spring period. Our results could lead to more reliable hydrological extreme predictions for policymakers and stakeholders in the water management sector, and for better mitigation and climate adaptations. Key Points A dynamical-statistical method for a long-lead drought prediction was developed. The method can increase the skill of up to 6-month lead SPEI predictions. SPEI prediction is suitable for identifying droughts under the global warming. ©2012. American Geophysical Union. All Rights Reserved.

Abdelwahab A.A.,Assiut University | Shim Y.-B.,Pusan National University
Sensors and Actuators, B: Chemical | Year: 2014

A novel method for highly sensitive H2O2 sensor is proposed using silver nanoparticles (AgNPs) modified oxidized poly-2,2′:5′,2′′-terthiophene-3-p-benzoic acid/multi wall carbon nanotube (Ox-pTTBA/MWCNT). The Ox-pTTBA/MWCNT nanocomposite film was prepared via electropolymerization of a TTBA monomer and MWCNT mixture solution, followed by in situ electrooxidation of the pTTBA/MWCNT film. Then, AgNPs were formed on the Ox-pTTBA/MWCNT layer through immersing the freshly prepared Ox-pTTBA/MWCNT electrode in AgNPs solution. The characterization of sensor probe and experimental parameters affecting its activity were investigated employing UV-vis spectroscopy, transition electronic microscopy (TEM), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). The AgNPs/Ox-pTTBA/MWCNT nanocomposite showed an excellent electrocatalytic activity to H2O2 by significantly increasing the reduction peak current and completely inhibiting the effect of other interfering species. The sensor probe displays a fast response time less than 5 s with a linear range from 10 to 260 μM and detection limit of 0.24 μM. The sensitive, stable and specific response to H2O2 demonstrates that the present sensor is potentially suitable for monitoring H2O2 concentrations in biological system. The application was conducted for the determination of H2O2 in human urine real samples. © 2014 Elsevier B.V. All rights reserved.

Oh S.T.,University of Glasgow | Kim J.R.,University of South Wales | Premier G.C.,University of South Wales | Lee T.H.,Pusan National University | And 2 more authors.
Biotechnology Advances | Year: 2010

The need for cost-effective low-energy wastewater treatment has never been greater. Clean water for our expanding and predominantly urban global population will be expensive to deliver, eats into our diminishing carbon-based energy reserves and consequently contributes to green house gases in the atmosphere and climate change. Thus every potential cost and energy cutting measure for wastewater treatment should be explored. Microbial fuel cells (MFCs) could potentially yield such savings but, to achieve this, requires significant advances in our understanding in a few critical areas and in our designs of the overall systems. Here we review the research which might accelerate our progress towards sustainable wastewater treatment using MFCs: system control and modelling and the understanding of the ecology of the microbial communities that catalyse the generation of electricity. © 2010 Elsevier Inc.

Choi K.-Y.,Pusan National University | Byrnes C.T.,Bielefeld University
Advances in Astronomy | Year: 2010

We review models which generate a large non-Gaussianity of the local form. We first briefly consider three models which generate the non-Gaussianity either at or after the end of inflation; the curvaton scenario, modulated (p)reheating, and an inhomogeneous end of inflation. We then focus on ways of generating the non-Gaussianity during inflation. We derive general conditions which a product or sum separable potential must satisfy in order to generate a large local bispectrum during slow-roll inflation. As an application, we consider two-field hybrid inflation. We then derive a formalism not based on slow roll which can be applied to models in which the slow-roll parameters become large before inflation ends. An exactly soluble two-field model is given in which this happens. Finally, we also consider further non-Gaussian observables, a scale dependence of fNL and the trispectrum. Copyright © 2010 Christian T. Byrnes and Ki-Young Choi.

Im E.,Pusan National University | Jung J.,University of California at Los Angeles | Pothoulakis C.,University of California at Los Angeles | Rhee S.H.,University of California at Los Angeles
Gastroenterology | Year: 2014

Background & Aims Early-onset ulcerative colitis, which is considered severe colonic inflammation that develops in infants and young children, can be caused by alterations in interleukin (IL)-10 signaling, although other factors are involved in its pathogenesis. We investigated whether loss of phosphatase and tensin homologue (PTEN), which regulates many important cell functions such as cell proliferation, cell survival, and Toll-like receptor (TLR) signaling pathways, contributes to the development of colitis in Il10-/- mice. Methods We generated Il10-/- mice (in C57BL/6 and C3H/HeJBir background strains) with disruption of Pten in the intestinal epithelium (IntsΔPten/ΔPten;Il10-/- mice) and Ints ΔCont;Il10-/- (control) mice. Colon tissues were collected and histological, transmission electron microscopy, and gene expression analysis were performed. Fecal microbiota samples were analyzed by sequencing of 16S ribosomal RNA genes. We disrupted Tlr4 in Ints ΔPten/ΔPten;Il10-/- mice. Lipopolysaccharide signaling via TLR4 was blocked by treating mice with polymyxin B. Results Il10-/- mice developed colitis when they were 6 to 7 months old, whereas IntsΔPten/ΔPten;Il10-/- mice developed severe colitis and colon tumors by the time they were 36 days old. Within 3 months of birth, 80% of IntsΔPten/ΔPten;Il10 -/- mice developed severe colitis and colonic malignancy, whereas none of the IntsΔCont;Il10-/- mice had these phenotypes. IntsΔPten/ΔPten;Il10-/- mice had alterations in fecal microbiota compared with controls, such as increased proportions of Bacteroides species, which are gram negative. Disruption of Tlr4 or treating IntsΔPten/ΔPten;Il10-/- mice with polymyxin B delayed the development of colitis and reduced disease severity. Conclusions Disruption of Pten in the intestinal epithelium of Il10 -/- mice speeds the onset and increases the severity of colitis. Fecal microbiota from IntsΔPten/ΔPten;Il10-/- mice have increased proportions of Bacteroides species. Development of colitis is delayed and reduced by blocking TLR4 signaling. Ints ΔPten/ΔPten;Il10-/- mice may be studied as a model for early-onset ulcerative colitis and used to identify new therapeutic targets. © 2014 by the AGA Institute.

Seo J.K.,Queensland University of Technology | Seo J.K.,Pusan National University | Mahendran M.,Queensland University of Technology
Journal of Constructional Steel Research | Year: 2012

Recently developed cold-formed LiteSteel Beam (LSB) sections have found increasing popularity in residential, industrial and commercial buildings due to their light weight and cost-effectiveness. Another beneficial characteristic is that they allow torsionally rigid rectangular flanges to be combined with economical fabrication processes. Currently, there is significant interest in the use of LSB sections as flexural members in floor joist systems. When used as floor joists, these sections require openings in the web to provide access for inspection and other services. At present, however, there is no design method available that provides accurate predictions of the moment capacities of LSBs with web openings. This paper presents the results of an investigation of the buckling and ultimate strength behaviour of LSB flexural members with web openings. A detailed fine element analysis (FEA)-based parametric study was conducted with the aim of developing appropriate design rules and making recommendations for the safe design of LSB floor joists. The results include the required moment capacity curves for LSB sections with a range of web opening combinations and spans and the development of appropriate design rules for the prediction of the ultimate moment capacities of LSBs with web openings. © 2011 Elsevier Ltd. All rights reserved.

Kang H.,Pusan National University | Ryu D.,Chungnam National University
Astrophysical Journal | Year: 2011

We examine diffusive shock acceleration (DSA) of the pre-existing as well as freshly injected populations of non-thermal, cosmic-ray (CR) particles at weak cosmological shocks. Assuming simple models for thermal leakage injection and Alfvénic drift, we derive analytic, time-dependent solutions for the two populations of CRs accelerated in the test-particle regime. We then compare them with the results from kinetic DSA simulations for shock waves that are expected to form in intracluster media and cluster outskirts in the course of large-scale structure formation. We show that the test-particle solutions provide a good approximation for the pressure and spectrum of CRs accelerated at these weak shocks. Since the injection is extremely inefficient at weak shocks, the pre-existing CR population dominates over the injected population. If the pressure due to pre-existing CR protons is about 5% of the gas thermal pressure in the upstream flow, the downstream CR pressure can absorb typically a few to 10% of the shock ram pressure at shocks with a Mach number M ≲ 3, yet the re-acceleration of CR electrons can result in a substantial synchrotron emission behind the shock. The enhancement in synchrotron radiation across the shock is estimated to be about a few to several for M ∼ 1.5 and 10 2-103 for M ∼ 3, depending on the detail model parameters. The implication of our findings for observed bright radio relics is discussed. © 2011. The American Astronomical Society. All rights reserved.

Lee H.,University of Florida | Ha M.Y.,Pusan National University | Balachandar S.,University of Florida
International Journal of Multiphase Flow | Year: 2011

Recently Lee and Balachandar proposed analytically-based expressions for drag and lift coefficients for a spherical particle moving on a flat wall in a linear shear flow at finite Reynolds number. In order to evaluate the accuracy of these expressions, we have conducted direct numerical simulations of a rolling particle for shear Reynolds number up to 100. We assume that the particle rolls on a horizontal flat wall with a small gap separating the particle from the wall (L= 0.505) and thus avoiding the logarithmic singularity. The influence of the shear Reynolds number and the translational velocity of the particle on the hydrodynamic forces of the particle was investigated under both transient and the final drag-free and torque-free steady state. It is observed that the quasi-steady drag and lift expressions of Lee and Balachandar provide good approximation for the terminal state of the particle motion ranging from perfect sliding to perfect rolling. With regards to transient particle motion in a wall-bounded shear flow it is observed that the above validated quasi-steady drag and lift forces must be supplemented with appropriate wall-corrected added-mass and history forces in order to accurately predict the time-dependent approach to the terminal steady state. Quantitative comparison with the actual particle motion computed in the numerical simulations shows that the theoretical models quite effective in predicting rolling/sliding motion of a particle in a wall-bounded shear flow at moderate Re. © 2010 Elsevier Ltd.

Chauhan B.S.,Pusan National University | Kumar N.,Delhi Technological University | Cho H.M.,Kongju National University | Lim H.C.,Pusan National University
Energy | Year: 2013

In order to meet the growing global energy requirement, exhaustive research is carried to develop and use variety of renewable fuels. Main objective of the present study is to compare the performance, emissions and combustion characteristics of biodiesel derived from non-edible Karanja oil in an unmodified diesel engine and to compare the results with baseline results of diesel fuel. Important physico-chemical properties of Karanja oil after transesterification were experimentally evaluated and found within acceptable limits of relevant standards. The performance parameters evaluated in the present study includes brake thermal efficiency of Karanja biodiesel with different compositions at 5%, 10%, 20%, 30% and 100% with mineral Diesel. BTE was about 3-5% lower with Karanja biodiesel and its blends with respect to diesel. Also, emissions parameters such as carbon monoxide, carbon dioxide, UBHC (unburned hydrocarbon), oxides of nitrogen and smoke opacity for different test fuels were also measured. UBHC, CO, CO2 and smoke were lower with Karanja biodiesel fuel. However, NOx emissions of Karanja biodiesel and its blend were higher than Diesel. The combustion analysis was done using peak cylinder pressure and heat release rate with respect to crank angle. The peak cylinder pressure and heat release rate was lower for Karanja biodiesel. The results from the experiments suggest that biodiesel from non-edible oil like Karanja and its blends with diesel could be a potential fuel for diesel engine and play a vital role in the near future especially for small and medium energy production. © 2013 Elsevier Ltd.

Kim S.-K.,Pusan National University | Raj C.J.,Dongguk University | Kim H.-J.,Pusan National University
Electronic Materials Letters | Year: 2014

Zinc oxide (ZnO) films were deposited on fluorine-doped tin oxide (FTO) glass substrates with the application of polysulfide redox reactions and a CuS counter electrode to fabricate CdS/CdSe quantum dot-sensitized solar cells (QDSCs). In the present study, ZnO nanoparticles were deposited in the interstices of the ZnO nanorods. The performance of the QDSCs was improved by the ZnO nanoparticle/ nanorod composite structure because the ZnO nanorods exhibit high electron transport, and while the ZnO nanoparticles have a large surface area for QD deposition. The ZnO nanoparticle/nanorod composite films represent a promising achievement for enhancing the conversion efficiency of QDSCs.[Figure not available: see fulltext.]. © 2014, The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.

Kang H.,Pusan National University | Petrosian V.,Stanford University | Ryu D.,UNIST | Jones T.W.,University of Minnesota
Astrophysical Journal | Year: 2014

We consider a phenomenological model for the thermal leakage injection in the diffusive shock acceleration (DSA) process, in which suprathermal protons and electrons near the shock transition zone are assumed to have the so-called κ-distributions produced by interactions of background thermal particles with pre-existing and/or self-excited plasma/MHD waves or turbulence. The κ-distribution has a power-law tail, instead of an exponential cutoff, well above the thermal peak momentum. So there are a larger number of potential seed particles with momentum, above that required for participation in the DSA process. As a result, the injection fraction for the κ-distribution depends on the shock Mach number much less severely compared to that for the Maxwellian distribution. Thus, the existence of κ-like suprathermal tails at shocks would ease the problem of extremely low injection fractions, especially for electrons and especially at weak shocks such as those found in the intracluster medium. We suggest that the injection fraction for protons ranges 10-4-10-3 for a κ-distribution with 10 ≲ κp ≲ 30 at quasi-parallel shocks, while the injection fraction for electrons becomes 10-6-10-5 for a κ-distribution with κe ≲ 2 at quasi-perpendicular shocks. For such κ values the ratio of cosmic ray (CR) electrons to protons naturally becomes K e/p ∼ 10-3-10 -2, which is required to explain the observed ratio for Galactic CRs. © 2014. The American Astronomical Society. All rights reserved..

Bolouri A.,Pusan National University | Shahmiri M.,Iran University of Science and Technology | Kang C.G.,Pusan National University
Journal of Alloys and Compounds | Year: 2011

The effects of compression ratios on the microstructure evolution of semisolid Al7075 alloy produced by the strain induced melt activation (SIMA) process were investigated. The samples were cold deformed by compression into the different heights up to 40% reduction. The isothermal holding treatments within mushy zone of the alloy were carried out at 610, 620 and 625 °C for predetermined time intervals. The results revealed that the average grain size gradually reduced with the increase in the compressive ratio. While the compressive ratio surpassed 30%, the descending trend above was not as evident as that of below 30% reduction. The optimum condition presenting the minimum grain size and the maximum shape factor with the highest uniformity is discussed. During the subsequent mushy zone heating, the recrystallization was induced in the deformed samples by the increasingly accumulated strain energy. © 2010 Elsevier B.V. All rights reserved.

Kang H.,Pusan National University | Ryu D.,Chungnam National University | Jones T.W.,University of Minnesota
Astrophysical Journal | Year: 2012

Recent radio observations have identified a class of structures, so-called radio relics, in clusters of galaxies. The radio emission from these sources is interpreted as synchrotron radiation from GeV electrons gyrating in μG-level magnetic fields. Radio relics, located mostly in the outskirts of clusters, seem to associate with shock waves, especially those developed during mergers. In fact, they seem to be good structures to identify and probe such shocks in intracluster media (ICMs), provided we understand the electron acceleration and re-acceleration at those shocks. In this paper, we describe time-dependent simulations for diffusive shock acceleration at weak shocks that are expected to be found in ICMs. Freshly injected as well as pre-existing populations of cosmic-ray (CR) electrons are considered, and energy losses via synchrotron and inverse Compton are included. We then compare the synchrotron flux and spectral distributions estimated from the simulations with those in two well-observed radio relics in CIZA J2242.8+5301 and ZwCl0008.8+5215. Considering that CR electron injection is expected to be rather inefficient at weak shocks with Mach number M ≲ a few, the existence of radio relics could indicate the pre-existing population of low-energy CR electrons in ICMs. The implication of our results on the merger shock scenario of radio relics is discussed. © © 2012. The American Astronomical Society. All rights reserved.

Lee C.-H.,Pusan National University | Lee C.-H.,State University of New York at Stony Brook | Zahed I.,State University of New York at Stony Brook
Physical Review C - Nuclear Physics | Year: 2014

We discuss the general features of the electromagnetic radiation from a thermal hadronic gas as constrained by chiral symmetry. The medium effects on the electromagnetic spectral functions and the partial restoration of chiral symmetry are quantified in terms of the pion densities. The results are compared with the electromagnetic radiation from a strongly interacting quark-gluon plasma in terms of the leading gluon condensate operators. We use the spectral functions as constrained by the emission rates to estimate the electric conductivity, the light flavor susceptibility and diffusion constant across the transition from the correlated hadronic gas to a strongly interacting quark-gluon plasma. © 2014 American Physical Society.

Zhao X.,Pusan National University | Zhao X.,Chongqing University | Kim S.-Y.,National Academy of Agricultural science NAAS | Park K.-Y.,Pusan National University
Journal of Medicinal Food | Year: 2013

Bamboo salt is a traditional food widely used in Korea. The in vitro anticancer effects of this salt were evaluated in HCT-116 human colon cancer cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. A 1% salt concentration of bamboo salt baked nine times (9×) inhibited the growth of HCT-116 cells by 53%, which was higher than salt baked three times (3×) or once (1×; 44% and 41%, respectively) and much higher than solar sea salt (Korean sea salt) and purified salt (22% and 18%, respectively). To elucidate the inhibitory mechanisms underlying the anticancer effect of the salt samples in cancer cells, expression of genes associated with apoptosis, inflammation, and metastasis was measured with reverse transcription-polymerase chain reaction and Western blotting. Bamboo salt (9×) significantly induced apoptosis in cancer cells (P<.05) by upregulating Bax, caspase-9, and caspase-3, and downregulating Bcl-2. The expression of genes associated with inflammation (NF-κB, iNOS, and COX-2) was significantly downregulated (P<.05) by 9× bamboo salt, demonstrating its anti-inflammatory properties. The 9× bamboo salt also exerted a greater anti-metastatic effect on cancer cells than the other salts as demonstrated by decreased mRNA expression of MMP genes and increased expression of tissue inhibitors of metalloproteinases, which was confirmed by the inhibition of tumor metastasis induced in colon 26-M3.1 cells in BALB/c mice. In contrast, purified and solar salts increased metastasis in the mice. Our results demonstrated that 9× bamboo salt had the most potent in vitro anticancer effect, induced apoptosis, had anti-inflammatory activities, and exerted in vivo anti-metastatic effects. Additionally, the anticancer, anti-inflammatory, and anti-metastatic effects of the 1× and 3× bamboo salts were stronger than those of the purified and solar salts. © Copyright 2013, Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition.

Amaranatha Reddy D.,Pusan National University | Ma R.,Pusan National University | Choi M.Y.,Gyeongsang National University | Kim T.K.,Pusan National University
Applied Surface Science | Year: 2015

In this work, we have successfully synthesized ternary nanohybrid composite, ZnS-Ag2S wrapped with reduced graphene oxide (RGO) using hydrothermal method without any surfactant. We have accessed the photocatalytic ability of ZnS-Ag2S-RGO nanocomposite using the oxidation of Rhodamine B (RhB) under simulated sunlight irradiation. The superior photocatalytic ability of ZnS-Ag2S-RGO compared to bare ZnS, was ascribed to an efficient charge transfer from ZnS to Ag2S and graphene sheets. The recyclability results also demonstrated the excellent stability and reliability of the ZnS-Ag2S-RGO. In addition to the excellent photocatalytic degradation properties, the synthesized ZnS-Ag2S-RGO nanocomposite exhibited near white light emission, which implies that careful design and control of the composition could be lead to find application in near UV-white LEDs. The present work provides new insights into the synthesis and characterizations of ternary ZnS-Ag2S-RGO nanocomposites and its wide applications in the environmental protection issues. © 2014 Elsevier B.V. All rights reserved.

Kang H.,Pusan National University | Ryu D.,Chungnam National University
Astrophysical Journal | Year: 2013

We reexamine nonlinear diffusive shock acceleration (DSA) at cosmological shocks in the large-scale structure of the universe, incorporating wave-particle interactions that are expected to operate in collisionless shocks. Adopting simple phenomenological models for magnetic field amplification (MFA) by cosmic-ray (CR) streaming instabilities and Alfvénic drift, we perform kinetic DSA simulations for a wide range of sonic and Alfvénic Mach numbers and evaluate the CR injection fraction and acceleration efficiency. In our DSA model, the CR acceleration efficiency is determined mainly by the sonic Mach number Ms , while the MFA factor depends on the Alfvénic Mach number and the degree of shock modification by CRs. We show that at strong CR modified shocks, if scattering centers drift with an effective Alfvén speed in the amplified magnetic field, the CR energy spectrum is steepened and the acceleration efficiency is reduced significantly, compared to the cases without such effects. As a result, the postshock CR pressure saturates roughly at ∼20% of the shock ram pressure for strong shocks with Ms ≳ 10. In the test-particle regime (Ms ≲ 3), it is expected that the magnetic field is not amplified and the Alfvénic drift effects are insignificant, although relevant plasma physical processes at low Mach number shocks remain largely uncertain. © 2013. The American Astronomical Society. All rights reserved.

Lee H.J.,Gyeongsang National University | An S.,Pusan National University | Kim G.B.,Gyeongsang National University
Science of the Total Environment | Year: 2014

To study background levels of polybrominated diphenyl ethers (PBDEs) in Korea, concentrations of PBDEs were measured for creek and subtidal sediments around Goseong Bay. Total concentrations of PBDEs (σ19PBDE) in creek sediments ranged from 0.18 to 13.95ng/g dry weight and were about twice those in subtidal sediments. PBDE concentrations were about two orders of magnitude lower than those reported in industrially active regions of Korea and other countries. BDE 209 was a major congener, accounting for 79.0% and 78.5% of total PBDEs in creek and subtidal sediments, respectively. This is consistent with the high consumption of deca-BDE in Korea and the very high octanol-water partition coefficient of deca-BDE. The relative compositions of PBDEs in creek and subtidal sediments were similar. BDE 209 and σ19PBDE had statistically significant correlations with total organic carbon, the lower brominated congeners had a poor correlation with total organic carbon. © 2013 Elsevier B.V.

Kang H.,Pusan National University | Ryu D.,Chungnam National University
Astrophysical Journal | Year: 2010

We examine the test-particle solution for diffusive shock acceleration, based on simple models for thermal leakage injection and Alfvénic drift. The critical injection rate, ζc, above which the cosmic-ray (CR) pressure becomes dynamically significant depends mainly on the sonic shock Mach number, M, and preshock gas temperature, T1. In the hot-phase interstellar medium (ISM) and intracluster medium, ζc ≲ 10-3 for shocks with M ≲ 5, while ζc ≈ 10-4(T1/106 K)1/2 for shocks with M ≳ 10. For T1 = 106 K, for example, the test-particle solution would be valid if the injection momentum pinj >3.8p th (where pth is thermal momentum). This leads to a postshock CR pressure less than 10% of the shock ram pressure. If the Alfvén speed is comparable to the sound speed in the preshock flow, as in the hot-phase ISM, the power-law slope of CR spectrum can be significantly softer than the canonical test-particle slope. Then, the CR spectrum at the shock can be approximated by the revised test-particle power law with an exponential cutoff at the highest accelerated momentum, pmax(t ). An analytic form of the exponential cutoff is also suggested. © 2010. The American Astronomical Society. All rights reserved.

Ryu D.,Chungnam National University | Das S.,Indian Institute of Technology Guwahati | Kang H.,Pusan National University
Astrophysical Journal | Year: 2010

We studied howthe intergalactic magnetic field (IGMF) affects the propagation of super-Greisen-Zatsepin-Kuzmin (GZK) protons that originate from extragalactic sources within the local GZK sphere. To this end, we set up hypothetical sources of ultra-high-energy cosmic rays (UHECRs), virtual observers, and the magnetized cosmic web in a model universe constructed from cosmological structure formation simulations.We then arranged a set of reference objectsmimicking active galactic nuclei (AGNs) in the local universe,with which correlations of simulated UHECR events are analyzed.With our model IGMF, the deflection angle between the arrival direction of super-GZK protons and the sky position of their actual sources is quite large with a mean value of ? ∼ 15°? and a median value of ? ∼ 7°-10°. On the other hand, the separation angle between the arrival direction and the sky position of nearest reference objects is substantially smaller with S ∼ 3°? 5-4°, which is similar to the mean angular distance in the sky to nearest neighbors among the reference objects. This is a direct consequence of our model that the sources, observers, reference objects, and the IGMF all trace the matter distribution of the universe. The result implies that extragalactic objects lying closest to the arrival direction of UHECRs are not necessarily their actual sources. With our model for the distribution of reference objects, the fraction of super-GZK proton events, whose closest AGNs are true sources, is less than 1/3.We discussed implications of our findings for correlation studies of realUHECRevents. © 2010. The American Astronomical Society.

Kim Y.-M.,University of Minnesota | Jung C.,University of Minnesota | Jung C.,Korea Food Research Institute | Seo M.,University of Minnesota | And 6 more authors.
Molecular Cell | Year: 2015

mTORC1 plays a key role in autophagy as a negative regulator. The currently known targets of mTORC1 in the autophagy pathway mainly function at early stages of autophagosome formation. Here, we identify that mTORC1 inhibits later stages of autophagy by phosphorylating UVRAG. Under nutrient-enriched conditions, mTORC1 binds and phosphorylates UVRAG. The phosphorylation positively regulates the association of UVRAG with RUBICON, thereby enhancing the antagonizing effect of RUBICON on UVRAG-mediated autophagosome maturation. Upon dephosphorylation, UVRAG is released from RUBICON to interact with the HOPS complex, a component for the late endosome and lysosome fusion machinery, and enhances autophagosome and endosome maturation. Consequently, the dephosphorylation of UVRAG facilitates the lysosomal degradation of epidermal growth factor receptor (EGFR), reduces EGFR signaling, andsuppresses cancer cell proliferation and tumor growth. These results demonstrate that mTORC1 engages in late stages of autophagy and endosome maturation, defining a broader range of mTORC1 functions in the membrane-associated processes. © 2015 Elsevier Inc.

Kim B.J.,Pusan National University | Nam J.H.,Dongguk University | Kim S.J.,Hanyang University
Molecules and Cells | Year: 2011

The interstitial cells of Cajal (ICCs) are pacemakers in the gastrointestinal tract and transient receptor potential melastatin type 7 (TRPM7) is a candidate for pacemaker channels. The effect of the 5-lipoxygenase (5-LOX) inhibitors NDGA, AA861, MK886 and zileuton on pacemaking activity of ICCs was examined using the whole cell patch clamp technique. NDGA and AA861 decreased the amplitude of pacemaker potentials in ICC clusters, but the resting membrane potentials displayed little change, respectively. Also, perfusing NDGA and AA861 into the bath reduced both inward current and outward current in TRPM7- like current in single ICC, respectively. But, they had no effects on Ca 2+ activated Cl- currents. The 5-LOX inhibitors MK886 and zileuton were, however, ineffective in pacemaker potentials in ICC clusters and in TRPM7-like current in single ICC, respectively. A specific TRPC3 inhibitor, pyrazole compound (Pyr3), and a specific TRPM4 inhibitor, 9-phenanthrol, had no effects in pacemaker potentials in ICC clusters and in TRPM7-like current in single ICC. These results suggest that, among the tested 5-LOX inhibitors, NDGA and AA861 modulate the pacemaker activities of the ICCs, and that the TRPM7 channel can affect intestinal motility. ©2011 KSMCB.

Kim B.G.,Pusan National University | Jo J.Y.,Pusan National University | Cheong S.W.,Rutgers University
Journal of Solid State Chemistry | Year: 2013

Barium stannate, BaSnO 3 (BSO), with a cubic perovskite structure, has been highlighted as a promising host material for the next generation transparent oxide electrodes. This study examined theoretically the electronic structure and phonon structure of BSO using hybrid density functional theory based on the HSE06 functional. The electronic structure results of BSO were corrected by extending the phonon calculations based on the hybrid density functional. The fundamental thermal properties were also predicted based on a hybrid functional calculation. Overall, a detailed understanding of the electronic structure, phonon modes and phonon dispersion of BSO will provide a theoretical starting-point for engineering applications of this material. © 2012 Elsevier Inc. All rights reserved.

Kyae B.,Pusan National University | Shin C.S.,Rutgers University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

A small Higgs mass parameter mhu2 can be insensitive to various trial heavy stop masses, if a universal soft squared mass is assumed for the chiral superpartners and the Higgs boson at the grand unification (GUT) scale, and a focus point (FP) of mhu2 appears around the stop mass scale. The challenges in the FP scenario are (1) a too heavy stop mass (≈5TeV) needed for the 126 GeV Higgs mass and (2) the too high gluino mass bound (1.4TeV). For a successful FP scenario, we consider (1) a superheavy right-hand (RH) neutrino and (2) the first and second generations of hierarchically heavier chiral superpartners. The RH neutrino can move a FP in the higher energy direction in the space of (Q,mhu2(Q)), where Q denotes the renormalization scale. On the other hand, the hierarchically heavier chiral superpartners can lift up a FP in that space through two-loop gauge interactions. Precise focusing of mhu2(Q) is achieved with the RH neutrino mass of ∼1014GeV together with an order one (0.9-1.2) Yukawa coupling to the Higgs boson, and the hierarchically heavy masses of 15-20 TeV for the heavier generations of superpartners, when the U(1)R breaking soft parameters m1/2 and A0 are set to be 1 TeV at the GUT scale. Those values can naturally explain the small neutrino mass through the seesaw mechanism, and suppress the flavor violating processes in supersymmetric models. © 2014 American Physical Society.

Sim H.,Pusan National University | Cheong S.W.,Rutgers University | Kim B.G.,Pusan National University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

The effect of octahedral tilting of the ASnO3 (A = Ca, Sr, Ba) parent compound and bicolor ASnO3/A′SnO3 superlattice (A, A′ = Ca, Sr, Ba) is predicted from density-functional theory. In the ASnO3 parent compound, the structural phase transition as a function of the A-site cation size is correlated with the magnitude of the two octahedral tilting modes (a -a-c0 tilting and a0a0c+ tilting). The magnitude of octahedral tilting modes in the superlattices is analyzed quantitatively and is associated with that of constituent parent materials. ASnO3/A′SnO3 superlattices show the hybrid improper ferroelectricity resulting from the coupling of two octahedral tilting modes (a-a-c0 tilting and a0a0c+ tilting), which are also responsible for the structural phase transition from the tetragonal phase to the orthorhombic phase. Ferroelectricity due to A-site mirror symmetry breaking is a secondary order parameter for the orthorhombic phase transition in the bicolor superlattice and is related to the Γ5- symmetry mode. The coupling between tilting modes and the ferroelectric mode in the bicolor superlattice of ASnO3/A ′SnO3 is analyzed by group theory and symmetry mode analysis. © 2013 American Physical Society.

Choi K.-Y.,Korea Astronomy and Space Science Institute | Kyae B.,Pusan National University | Shin C.S.,Rutgers University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

For explaining the AMS-02 cosmic positron excess, which was recently reported, we consider a scenario of thermally produced and decaying dark matter (DM) into the standard model (SM) leptons with an extremely small decay rate, ΓDM∼10-26sec-1. Since the needed DM mass is relatively heavy (700GeV mDM 3000GeV), we introduce another DM component apart from the lightest supersymmetric particle (LSP). For its (meta-)stability and annihilation into other particles, the new DM should be accompanied with another Z2 symmetry apart from the R parity. Sizable renormalizable couplings of the new DM with SM particles, which are necessary for its thermalization in the early universe, cannot destabilize the new DM because of the new Z2 symmetry. Since the new DM was thermally produced, it can naturally explain the present energy density of the Universe. The new DM can decay into the SM leptons (and the lightest supersymmetric particle) only through nonrenormalizable operators suppressed by a superheavy squared mass parameter after the new Z2 symmetry is broken around TeV scale. We realize this scenario in a model of "gauged vectorlike leptons," which was proposed recently for the naturalness of the Higgs boson. © 2014 American Physical Society.

Edmon P.P.,University of Minnesota | Kang H.,Pusan National University | Jones T.W.,University of Minnesota | Ma R.,Chungnam National University
Monthly Notices of the Royal Astronomical Society | Year: 2011

We present calculations of expected continuum emissions from Sedov-Taylor phase Type Ia supernova remnants (SNRs), using the energy spectra of cosmic ray (CR) electrons and protons from non-linear diffusive shock acceleration simulations. A new, general-purpose radiative process code, cosmicp, was employed to calculate the radiation expected from CR electrons and protons and their secondary products. These radio, X-ray and gamma-ray emissions are generally consistent with current observations of Type Ia SNRs. The emissions from electrons in these models dominate the radio through X-ray bands. Decays of π0s from p-p collisions mostly dominate the gamma-ray range, although for a hot, low-density ISM case (nISM= 0.003cm-3), the pion decay contribution is reduced sufficiently to reveal the inverse Compton contribution to TeV gamma-rays. In addition, we present simple scalings for the contributing emission processes to allow a crude exploration of model parameter space, enabling these results to be used more broadly. We also discuss the radial surface brightness profiles expected for these model SNRs in the X-ray and gamma-ray bands. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Hong S.E.,Korea Institute for Advanced Study | Kang H.,Pusan National University | Ryu D.,UNIST
Astrophysical Journal | Year: 2015

Radio relics detected in the outskirts of galaxy clusters are thought to trace radio-emitting relativistic electrons accelerated at cosmological shocks. In this study, using the cosmological hydrodynamic simulation data for the large-scale structure formation and adopting a diffusive shock acceleration (DSA) model for the production of cosmic-ray (CR) electrons, we construct mock radio and X-ray maps of simulated galaxy clusters that are projected in the sky plane. Various properties of shocks and radio relics, including the shock Mach number, radio spectral index, and luminosity, are extracted from the synthetic maps and compared with observations. A substantial fraction of radio and X-ray shocks identified in these maps involve multiple shock surfaces along lines of sight (LOSs), and the morphology of shock distributions in the maps depends on the projection direction. Among multiple shocks in a given LOS, radio observations tend to pick up stronger shocks with flatter radio spectra, while X-ray observations preferentially select weaker shocks with larger kinetic energy flux. As a result, in some cases the shock Mach numbers and locations derived from radio and X-ray observations could differ from each other. We also find that the distributions of the spectral index and radio power of the synthetic radio relics are somewhat inconsistent with those of observed real relics; a bit more radio relics have been observed closer to the cluster core and with steeper spectral indices. We suggest that the inconsistency could be explained if very weak shocks with Ms ≲ 2 accelerate CR electrons more efficiently, compared with the DSA model adopted here. © 2015. The American Astronomical Society. All rights reserved..

Dongguk University and Pusan National University | Date: 2014-12-17

Disclosed is a wire knot delivery device, and more particularly, a wire knot delivery device for delivering and maintaining a knot of a medical wire in a medical procedure. The wire knot delivery device includes a first body, a second body parallel to the first body and moving relative to the first body, a first catching part connected to a side of the first body and caught by a side of the knot during the delivery of the knot, and a second catching part connected to a side of the second body and caught by another side of the knot during the delivery of the knot. As the second body moves, a distance between the first catching part and the second catching part is adjusted.

Chungnam National University and Pusan National University | Date: 2013-12-31

Provided are compounds for inhibiting Snail-p53 binding and therapeutic agents for cancer including the compounds as an effective component. The Snail-p53 binding inhibitors induce expression of p53 in K-Ras mutant cell lines, thereby enabling effective treatment or prevention of K-Ras mutant cancer, such as, pancreatic cancer, lung cancer, cholangioma, and colon cancer, of which diagnosis or treatment is not easy.

Provided are compounds for inhibiting Snail-p53 binding and therapeutic agents for cancer including the compounds as an effective component. The Snail-p53 binding inhibitors induce expression of p53 in K-Ras mutant cell lines, thereby enabling effective treatment or prevention of K-Ras mutant cancer, such as, pancreatic cancer, lung cancer, cholangioma, and colon cancer, of which diagnosis or treatment is not easy.

Disclosed are a pharmaceutical composition for the treatment of aging-related diseases, comprising a progerin expression inhibitor as an active ingredient, a novel compound inhibitory of binding between progerin and Lamin A, and a pharmaceutical composition for the prophylaxis or therapy of aging-related diseases, comprising the novel compound as an active ingredient. Capable of suppressing the overexpression of progerin and inhibiting binding between progerin and Lamin A, the pharmaceutical composition of the present invention is effective at treating or preventing diseases caused by progerin expression and progerin-Lamin A binding, particularly, renal cancer, leukemia, prostate cancer, and progeria, which are more apt to occur in an aged population. In addition, the screening method of the present invention allows the specific selection of a drug which is simulative of binding between pVHL and progerin, or inhibitory of binding between progerin and Lamin A, thereby developing an effective therapeutic agent for a disease caused in an aged population, such as renal cancer, leukemia, prostate cancer, and progeria.

Lee J.,Pusan National University | Jo D.-G.,Sungkyunkwan University | Park D.,Pusan National University | Chung H.Y.,Pusan National University | And 2 more authors.
Pharmacological Reviews | Year: 2014

During the past 5 decades, it has been widely promulgated that the chemicals in plants that are good for health act as direct scavengers of free radicals. Here we review evidence that favors a different hypothesis for the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for the latter mechanism is grounded in the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phyto-chemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examples of such pathways include those involving the transcription factors nuclear factor erythroid 2-related factor 2, nuclear factor-kB, hypoxia-inducible factor 1a, peroxisome proliferator-activated receptor g, and forkhead box subgroup O, as well as the production and action of trophic factors and hormones. Trans-lational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against tissue injury and disease. Because neurons are particularly sensitive to potentially noxious phytochemicals, we focus on the nervous system but also include findings from other cell types in which actions of phytochemicals on specific signal transduction pathways have been more thoroughly studied.

Lee S.-M.,Pusan National University | Saini S.S.,University of Waterloo | Jeong M.-Y.,Pusan National University
IEEE Photonics Technology Letters | Year: 2010

This study demonstrates simultaneous measurement of three parameters viz. refractive index of surrounding medium, temperature, and strain using etched-core fiber Bragg grating sensors. Simultaneous measurement is achieved by exciting higher order modes in the sensor using an asymmetric nonadiabatic taper and measuring difference in their Bragg wavelength shifts due to different parameters. In order to simultaneously measure three parameters, three different order modes were excited in the sensor. The ability to measure multiple parameters is useful in bio-chemical measurements as it allows us to compensate for the change in Bragg wavelength with respect to change in temperature or strain. Thus, the sensors do not need to be stabilized. © 2010 IEEE.

Lee B.-H.,Korea Maritime Institute | Park J.-C.,Pusan National University | Kim M.-H.,Texas A&M University | Hwang S.-C.,Pusan National University
Computer Methods in Applied Mechanics and Engineering | Year: 2011

The violent free-surface motions and the corresponding impact loads are numerically simulated by using the Moving Particle Semi-implicit (MPS) method, which was originally proposed by Koshizuka and Oka [10] for incompressible flows. In the original MPS method, there were several defects including non-optimal source term, gradient and collision models, and search of free-surface particles, which led to less-accurate fluid motions and non-physical pressure fluctuations. In the present study, how those defects can be remedied is illustrated by step-by-step improvements in the respective processes of the revised MPS method. For illustration, two examples are studied; (i) dam breaking problem and (ii) liquid sloshing inside a rectangular tank. The improvement of each step is explained and numerically demonstrated. The numerical results are also compared against the experimental results of Martin and Moyce [12] for dam-breaking problem and Kishev et al. [9] for sloshing problem. The numerical results for violent free-surface motions and impact pressures are in good agreement with their experimental data. © 2010 Elsevier B.V.

Kyae B.,Pusan National University | Park J.-C.,Sungkyunkwan University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

Light fermionic/scalar dark matter (DM) (mDM ≈ 8GeV) neutral under the standard model can be responsible for the CDMS and CoGeNT signals, and the Fermi-LAT gamma-ray excesses. In order to explain them in a relatively simple framework, we have explored various DM annihilation and scattering processes, discussing important phenomenological constraints coming from particle physics. Assuming that the two independent observations have a common DM origin and the processes arise through a common mediator, DM should annihilate into tau/anti-tau lepton pairs through an s-channel, and scatter with nuclei through a t-channel process. To avoid the p-wave suppression, a new Higgs-like scalar field with a mass of O(1)TeV is necessary as a common mediator of both the processes. We propose a supersymmetric model realizing the scenario. © 2014 The Authors.

Kim M.-K.,Pusan National University | Cho Y.-Y.,Pusan National University | Cho G.-M.,Dongseo University
Nonlinear Analysis: Real World Applications | Year: 2013

In this paper, we propose new large-update path-following interior-point algorithms for P*(κ)-nonlinear complementarity problems (NCPs). We define new classes of parametric kernel functions and based on these functions new search directions and proximity measures are defined. We show that if a strictly feasible starting point is available and the undertaken problem satisfies certain conditions, then new large-update path-following interior-point algorithms for P*(κ)-NCPs have O((1+2κ)nlognlogn μ0ε) iteration complexity which is currently the best known result for such methods. © 2012 Published by Elsevier Ltd.

Wu C.,University of Maryland University College | Lee D.,Pusan National University | Zachariah M.R.,University of Maryland University College
Langmuir | Year: 2010

The ability to manipulate miniature object assemblies with well-defined structures in a controllable manner is of both fundamental and applied interests. This article presents general strategies, with nanospheres as building blocks, to engineer mesoscopic spherical architectures via a process of evaporation-driven self-assembly in aerosol droplets. Uniform magnetite iron oxide (Fe3O4, ̃2.5 nm), silica (SiO2, ̃15 nm), and cupric oxide (CuO, ̃6 nm) nanoparticles were employed for the structural architecture. The method enables microstructural control of the self-assembled mesospheres by tuning the competition between solvent evaporation and solute diffusion within an aerosol droplet. Furthermore, we have demonstrated it is technically feasible to assemble surface-dissimilar binary components, i.e., charge-stabilized hydrophilic SiO2 and hydrophobic ligand-capped Fe3O4 nanoparticles, into hierarchical composite structures, which could be extended for preparation of more hierarchically textured materials with desired functionalities. © 2010 American Chemical Society.

Jang Y.H.,Pusan National University | Jang Y.H.,Sungkyunkwan University | Choi K.Y.,Yonsei University | Min D.S.,Pusan National University | Min D.S.,Yonsei University
Cell Death and Differentiation | Year: 2014

Autophagy is a catabolic process in which cell components are degraded to maintain cellular homeostasis by nutrient limitations. Defects of autophagy are involved in numerous diseases, including cancer. Here, we demonstrate a new role of phospholipase D (PLD) as a regulator of autophagy. PLD inhibition enhances autophagic flux via ATG1 (ULK1), ATG5 and ATG7, which are essential autophagy gene products critical for autophagosome formation. Moreover, PLD suppresses autophagy by differentially modulating phosphorylation of ULK1 mediated by mTOR and adenosine monophosphate-activated protein kinase (AMPK), and by suppressing the interaction of Beclin 1 with vacuolar-sorting protein 34 (Vps34), indicating that PLD coordinates major players of the autophagic pathway, AMPK-mTOR-ULK1 and Vps34/Beclin 1. Ultimately, PLD inhibition significantly sensitized in vitro and in vivo cancer regression via genetic and pharmacological inhibition of autophagy, providing rationale for a new therapeutic approach to enhancing the anticancer efficacy of PLD inhibition. Collectively, we show a novel role for PLD in the molecular machinery regulating autophagy. © 2014 Macmillan Publishers Limited All rights reserved.

Tramm T.,Aarhus University Hospital | Kim J.-Y.,Pusan National University | Tavassoli F.A.,Yale University
American Journal of Surgical Pathology | Year: 2011

The presence of myoepithelial (ME) cells is considered an important feature in the vast majority of benign breast lesions. Recently, a case showing the absence of myoepithelium in a mammary duct with apocrine metaplasia was reported. To investigate the status of ME cells associated with apocrine metaplasia, the distribution of ME cells in 59 metaplastic and intraductal proliferative apocrine lesions was evaluated using immunohistochemical expression of p63 and Calponin. p63 showed a diminished number of ME cells and increased intermyoepithelial nuclear distance in ducts with all variants of apocrine metaplasia and proliferation compared with normal glands. In the majority of cases, Calponin showed a continuous ME layer. In 6 cases, including an apocrine papilloma, there were definitive ME gaps confirmed by both markers, in the absence of atypia and with preservation of the basement membrane. In all cases, there was frequent heterogeneity in the distribution of ME cells in ducts harboring apocrine cells and even in various papillae within papillary lesions. In summary, benign and noninvasive apocrine lesions can show reduction and occasional complete loss of ME cells. This observation is particularly important when evaluating apocrine papillary proliferations, in which the absence of ME cells may lead to overdiagnosis of atypia and/or malignancy. The observation suggests that at least 2 ME markers should be used when evaluating apocrine lesions, and that a malignant diagnosis should be based on features of the proliferating cells until more data become available on the significance, if any, of the absence of ME cells in apocrine lesions. Copyright © 2011 by Lippincott Williams & Wilkins.

Yun W.Y.,Pusan National University | Cha J.H.,Ewha Womans University
Reliability Engineering and System Safety | Year: 2010

Redundancy or standby is a technique that has been widely applied to improving system reliability and availability in the stage of system design. In this paper, we consider a standby system with two units in which the first unit (unit 1) starts its operation under active state and the other unit (unit 2) is under cold standby state at the starting point. After a specified time s (switching time), the state of unit 2 is changed to warm standby state and, as soon as the operating unit 1 fails, the state of unit 2 is changed to active state. If unit 1 fails before time s, the system fails. Units can fail at both active and warm standby states. A general method for modeling the standby system is adopted and system performance measures (system reliability and mean life) based on the proposed model are derived. Three models -a perfect switching model and two imperfect switching models -are considered in this paper. Two imperfect switching models include an imperfect switching probability and a preliminary warm-up period which is required for the change from cold standby state to warm standby state. We consider the problem of determining the optimal switching time which maximizes the expected system life and related allocation problem is also discussed. Some numerical examples are studied. © 2010 Elsevier Ltd. All rights reserved.

Hong K.-S.,Pusan National University | Naseer N.,Pusan National University | Kim Y.-H.,Sungkyunkwan University
Neuroscience Letters | Year: 2015

Functional near-infrared spectroscopy (fNIRS) is an optical imaging method that can be used for a brain-computer interface (BCI). In the present study, we concurrently measure and discriminate fNIRS signals evoked by three different mental activities, that is, mental arithmetic (MA), right-hand motor imagery (RI), and left-hand motor imagery (LI). Ten healthy subjects were asked to perform the MA, RI, and LI during a 10. s task period. Using a continuous-wave NIRS system, signals were acquired concurrently from the prefrontal and the primary motor cortices. Multiclass linear discriminant analysis was utilized to classify MA vs. RI vs. LI with an average classification accuracy of 75.6% across the ten subjects, for a 2-7. s time window during the a 10. s task period. These results demonstrate the feasibility of implementing a three-class fNIRS-BCI using three different intentionally-generated cognitive tasks as inputs. © 2014 Elsevier Ireland Ltd.

Li G.,University of Maryland University College | Hwang Y.,University of Maryland University College | Radermacher R.,University of Maryland University College | Chun H.-H.,Pusan National University
Energy | Year: 2013

This paper reviews the recent development of available cold storage materials for subzero applications. According to the type of a storage medium and the way of the storage medium is used, phase change material (PCM) storage and sorption storage are introduced separately. Eutectic water-salt solutions and non-eutectic water-salt solution PCMs are discussed from thermal and physicochemical properties such as fusion heat, thermal conductivity, phase separation, supercooling, corrosion, flammability, etc. Related solutions for issues of such PCMs are offered. Microencapsulated PCMs are introduced as they have an excellent heat transfer performance to the surroundings because of the large surface per volume of the capsules and the excellent cycling stability due to the restricted phase separation in microscopic distances. PCMs with nanoparticle additives are also discussed as they have higher thermal conductivity for better storage process. Absorption and adsorption storages are mainly discussed for their working pairs, heat transfer enhancement and system performance improvement aspects. Relevant perspective technologies are discussed for further work. © 2012 Elsevier Ltd.

Rehan M.,Pakistan Institute of Engineering and Applied Sciences | Hong K.-S.,Pusan National University
Nonlinear Dynamics | Year: 2013

This paper presents a comprehensive study on a dynamic nonlinear anti-windup compensator (AWC) design for nonlinear systems. It is shown that for asymptotically stable nonlinear systems, a full-order internal model control (IMC)-based AWC always exists regardless of the nonlinearity type. An alternative decoupled-architecture-based AWC offering better performance is proposed, wherein the selection of a nonlinear dynamical component plays a key role in establishing an equivalent decoupled architecture. Using the decoupled architecture, a quadratic Lyapunov function, the Lipschitz condition, the sector condition, and L 2 gain reduction, a linear matrix inequality (LMI)-based AWC scheme is developed for systems with global Lipschitz nonlinearities. And by means of the local sector condition, a decoupled-architecture-based local AWC scheme (utilizing LMIs) for unstable and chaotic systems, which simultaneously guarantees a region of stability and the closed-loop performance for tracking-control applications, is derived. Simulation results establishing the effectiveness of the proposed AWC schemes are provided. © 2013 Springer Science+Business Media Dordrecht.

Rehan M.,Pakistan Institute of Engineering and Applied Sciences | Hong K.-S.,Pusan National University
Computational and Mathematical Methods in Medicine | Year: 2012

Synchronization of chaotic neurons under external electrical stimulation (EES) is studied in order to understand information processing in the brain and to improve the methodologies employed in the treatment of cognitive diseases. This paper investigates the dynamics of uncertain coupled chaotic delayed FitzHugh-Nagumo (FHN) neurons under EES for incorporated parametric variations. A global nonlinear control law for synchronization of delayed neurons with known parameters is developed. Based on local and global Lipschitz conditions, knowledge of the bounds on the neuronal states, the Lyapunov-Krasovskii functional, and the L2 gain reduction, a less conservative local robust nonlinear control law is formulated to address the problem of robust asymptotic synchronization of delayed FHN neurons under parametric uncertainties. The proposed local control law guarantees both robust stability and robust performance and provides the L2 bound for uncertainty rejection in the synchronization error dynamics. Separate conditions for single-input and multiple-input control schemes for synchronization of a wide class of FHN systems are provided. The results of the proposed techniques are verified through numerical simulations. © 2012 Muhammad Rehan and Keum-Shik Hong.

Jang D.-W.,Korea Maritime Institute | Kim S.W.,Pusan National University | Kim K.H.,Pusan National University
International Journal of Production Economics | Year: 2013

This paper addresses the optimization of a block stacking storage system (BSSS) in which unit loads are stored vertically. One of the important problems in a BSSS is in the relocation required when unit loads are located on top of the next unit load to be picked. Relocations are bound to occur when multiple types of unit loads are mixed in the same stacking area. Relocation is a major source of inefficiency during a BSSS handling operation. This study shows how the number of relocations can be reduced by utilizing the information regarding the arriving unit load type when determining its storage location. For the case where the information is not available, statistical models have been developed that estimate the expected number of relocations. For the case where the information is available and utilized, a method based on a genetic algorithm is suggested for use in determining the storage location for each arriving unit load in such a way that minimizes the expected number of relocations. A discussion is presented regarding how to determine the optimal number of stacks allocated to a set of unit load types which will share the same storage area considering the expected number of relocations. © 2012 Elsevier B.V. All rights reserved.

Hwang J.,Dongseo University | Hyun S.S.,Pusan National University
International Journal of Hospitality Management | Year: 2013

The purposes of this study were to (1) examine the triggers of patrons' nostalgia and (2) examine how the nostalgia triggers induce patrons' emotional responses, thus influencing revisit intentions. Based on a literature review, 20 triggers that induce nostalgia were derived. The empirical data utilized in this study was collected from 438 luxury restaurant patrons who had visited a luxury restaurant more than 60 days prior to responding to the survey. The initial responses were then examined using exploratory factor analysis (EFA). The EFA results indicated that patrons' nostalgia is induced by four factors: 'food', 'event', 'environment', and 'staff'. Subsequent data analysis revealed that all four triggers of personal nostalgia bear a significant impact on inducing patrons' pleasurable responses. Moreover, it was revealed that hiatus plays a significant moderating role in the relationship between nostalgia and patron's pleasurable responses. In other words, as time elapses following a restaurant visit, nostalgia triggers leads to higher levels of pleasurable responses regarding their experiences in the restaurant. Finally, such pleasurable responses lead to revisit intentions. Based on these findings, possible interpretations and managerial implications are suggested in the latter part of the study. © 2012 Elsevier Ltd.

Lee S.-M.,Pusan National University | Jeong M.-Y.,Pusan National University | Saini S.S.,University of Waterloo
Journal of Lightwave Technology | Year: 2012

In this paper, we demonstrate a fiber Bragg grating sensor for bio-chemical detection. In the sensor area, the fiber has been chemically etched to the core with a diameter of 7 μm. Due to increased index contrast, the etched-core fiber Bragg grating supports multiple guided modes which respond differently to the refractive index of the surrounding medium, temperature and the strain. An asymmetric adiabatic taper is created between the etched and the unetched parts of the fiber resulting in excitation of both the symmetrical and the asymmetrical modes which can be interrogated with an erbium doped fiber amplifier amplified spontaneous emission source. The sensor is integrated with a Polydimethylsiloxane (PDMS) microfluidic channel for introduction of chemicals to be tested. A refractive index sensitivity of 92 nm/riu was achieved using the 3rd order mode. Further the sensor can simultaneously measure the refractive index, temperature and strain to an accuracy of 1 × 10 -4, 0.32 °C and 10 με assuming a wavelength resolution of 0.01 nm. By using signal processing, these resolutions can be improved by a factor of 10. © 2006 IEEE.

Rehan M.,Pakistan Institute of Engineering and Applied Sciences | Hong K.-S.,Pusan National University
PLoS ONE | Year: 2013

This paper discusses modeling and automatic feedback control of (postural and rest) tremor for adaptive-control-methodology-based estimation of deep brain stimulation (DBS) parameters. The simplest linear oscillator-based tremor model, between stimulation amplitude and tremor, is investigated by utilizing input-output knowledge. Further, a nonlinear generalization of the oscillator-based tremor model, useful for derivation of a control strategy involving incorporation of parametric-bound knowledge, is provided. Using the Lyapunov method, a robust adaptive output feedback control law, based on measurement of the tremor signal from the fingers of a patient, is formulated to estimate the stimulation amplitude required to control the tremor. By means of the proposed control strategy, an algorithm is developed for estimation of DBS parameters such as amplitude, frequency and pulse width, which provides a framework for development of an automatic clinical device for control of motor symptoms. The DBS parameter estimation results for the proposed control scheme are verified through numerical simulations. © 2013 Rehan, Hong.

Park S.H.,Dongseo University | Han S.I.,Pusan National University
IET Control Theory and Applications | Year: 2011

This study deals with a robust non-smooth non-linearity compensation scheme for the direct-drive robot manipulator with an asymmetric deadzone, dynamic friction in joints and between the environmental contact space and end-effector and uncertainty. A model-free recurrent fuzzy neural network (RFNN) control system to approximate the ideal backstepping control law is designed to replace the traditional model-based adaptive controller, which requires information on the robots dynamics in advance. The simple dead-zone estimator and friction compensator based on the elasto-plastic friction model are developed in order to estimate unknown dead-zone width and friction parameters. The Lyapunov stability analysis yields the adaptive laws of the RFNN controller as well as the estimators of a dead-zone width and an elasto-plastic friction parameter. The validity of the proposed control scheme is confirmed from simulated results for free and constrained direct-drive robots with a deadzone in joint actuator, dynamic friction in joints and contact surfaces of the end-effector and uncertainty. © 2011 The Institution of Engineering and Technology.

Kim S.-M.,Pusan National University | Seo S.-W.,Sungkyunkwan University | Lee J.-Y.,Sungkyunkwan University | Sung K.-S.,Sungkyunkwan University
International Orthopaedics | Year: 2012

Purpose The treatment of symptomatic Schwannoma is surgical excision. However, in the case of major peripheral nerves with motor function, there are concerns including neurological complications following surgery. This study was designed to evaluate the surgical outcome of Schwannomas originating from major peripheral nerves of the lower limb. Additionally, we sought to find out the predictable factors for permanent neurological deficits. Methods Between 2004 and 2008, 30 consecutive Schwannomas underwent simple excision or enucleation. Surgical outcomes after excision were evaluated with an emphasis on neurological deficits and recurrence. Neurological complications were classified as major or minor neurological deficits and evaluated immediately after surgery and at final follow-up. Risk factors for development of neurological deficits were identified. Results Twenty-three patients (23/30, 76.7 %) developed neurological deficits immediately after surgery. After a mean of 58.8 months (32-79 months), 19 patients (19/30, 63.3 %) showed no residual neurological deficits.Among the remaining 11 (11/30, 36.7 %), nine patients had tolerable symptoms and two patients had major neurological deficits including significantmotor weakness and sensory impairments. Larger tumours tended to be at greater risk of neurological deficit after surgery. One recurrence of the tumour was seen two years after surgery. There were no cases of reoperation or malignant transformation Conclusions In the majority of cases, Schwannomas in the lower limb can be excised with acceptable risk for neurological deficits. However, meticulous dissection is required in large-sized Schwannomas because these tumours seem to have a higher frequency of fascicular injury during dissection. © Springer-Verlag 2012.

Lee J.-H.,Postal Technology Research Center | Moon I.-K.,Pusan National University | Park J.-H.,Postal Technology Research Center
International Journal of Production Research | Year: 2010

Recently, the multi-level and multi-facility industrial problem in supply chain management (SCM) has been widely investigated. One of the key issues, central to this problem in the current SCM research area is the interdependence among the location of facilities, the allocation of facilities, and the vehicle routing for the supply of raw materials and products. This paper studies the supply chain network design problem, which involves the location of facilities, allocation of facilities, and routing decisions. The proposed problem has some practical applications. For example, it is necessary for third party logistics (3PL) companies to manage the design of the network and to operate vehicle transportation. The purpose of this study is to determine the optimal location, allocation, and routing with minimum cost to the supply chain network. The study proposes two mixed integer programming models, one without routing and one with routing, and a heuristic algorithm based on LP-relaxation in order to solve the model with routing. The results show that a developed heuristic algorithm is able to find a good solution in a reasonable time. © 2010 Taylor & Francis.

Kim M.-J.,Pusan National University | Kang D.-K.,Dongseo University
Expert Systems with Applications | Year: 2012

Ensemble learning is a method to improve the performance of classification and prediction algorithms. Many studies have demonstrated that ensemble learning can decrease the generalization error and improve the performance of individual classifiers and predictors. However, its performance can be degraded due to multicollinearity problem where multiple classifiers of an ensemble are highly correlated with. This paper proposes a genetic algorithm-based coverage optimization technique in the purpose of resolving multicollinearity problem. Empirical results with bankruptcy prediction on Korea firms indicate that the proposed coverage optimization algorithm can help to design a diverse and highly accurate classification system. © 2012 Elsevier Ltd. All rights reserved.

Lee M.H.,Yonsei University | Han D.-W.,Pusan National University | Hyon S.-H.,Medical Simulation | Park J.-C.,Yonsei University
Apoptosis | Year: 2011

Animal tumor bioassays and in vitro cell culture systems have demonstrated that epigallocatechin-3-O-gallate (EGCG), the predominant catechin in green tea, possesses anti-proliferative and pro-apoptotic effects on various cancer cells and tumors. In this study, we investigated the effects of EGCG on cell growth, cell cycle progression, and apoptosis in human fibrosarcoma HT-1080 cells. The involvement of p53, Bcl-2, Bax, caspases, and nuclear factor-κB (NF-κB) was examined as a mechanism for the anti-cancer activity of EGCG. Time-dependent intracellular trafficking of EGCG was also determined using fluorescein isothiocyanate (FITC)-conjugated EGCG (FITC-EGCG). Our data show that EGCG treatment caused dose-dependent cell growth inhibition, cell cycle arrest at the G0/G1 phase, and DNA fragmentation suggesting the induction of apoptosis in HT-1080 cells. Immunoblot analysis revealed that the expression of p53, caspase-7 and -9 as well as the ratio of Bax/Bcl-2 protein increased significantly with higher EGCG concentrations and longer incubation times. Moreover, expression of phosphorylated NF-κB/p65 in HT-1080 cells was inhibited by EGCG treatment in a dose-dependent manner, while that of unphosphorylated NF-κB/p65 remained unaffected. Here we also reveal time-dependent internalization of FITC-EGCG into the cytosol of HT-1080 cells and its subsequent nuclear translocation. These results suggest that EGCG may interrupt exogenous signals directed towards genes involved in proliferation and cell cycle progression. Taken together, our data indicate that HT-1080 apoptosis may be mediated through the induction of p53 and caspases by the pro-oxidant activity of internalized EGCG, as well as suppression of Bcl-2 and phosphorylated NF-κB by the antioxidant activity of EGCG. © 2010 Springer Science+Business Media, LLC.

Caprioli D.,National institute for astrophysics | Kang H.,Pusan National University | Vladimirov A.E.,Stanford University | Jones T.W.,University of Minnesota
Monthly Notices of the Royal Astronomical Society | Year: 2010

We provide a both qualitative and quantitative comparisons among different approaches aimed at solving the problem of non-linear diffusive acceleration of particles at shocks. In particular, we show that state-of-the-art models (numerical, Monte Carlo and semi-analytical), even if based on different physical assumptions and implementations, for typical environmental parameters lead to very consistent results in terms of shock hydrodynamics, cosmic ray spectrum and also escaping flux spectrum and anisotropy. Strong points and limits of each approach are also discussed, as a function of the problem one wants to study. © 2010 The Authors. Journal compilation © 2010 RAS.

Kim J.H.,Seoul National University | Park J.H.,Seoul National University | Chung Y.K.,Seoul National University | Park K.H.,Pusan National University
Advanced Synthesis and Catalysis | Year: 2012

This communication describes a ruthenium nanoparticle-catalyzed reduction of nitroarenes giving azoxyarenes, azoarenes, or anilines in good to excellent yields using ethanol as a hydrogen source. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lee J.-Y.,University of Hawaii at Manoa | Lee S.-S.,Pusan National University | Wang B.,University of Hawaii at Manoa | Ha K.-J.,Pusan National University | Jhun J.-G.,Seoul National University
Climate Dynamics | Year: 2013

Efforts have been made to appreciate the extent to which we can predict the dominant modes of December-January-February (DJF) 2 m air temperature (TS) variability over the Asian winter monsoon region with dynamical models and a physically based statistical model. Dynamical prediction was made on the basis of multi-model ensemble (MME) of 13 coupled models with the November 1 initial condition for 21 boreal winters of 1981/1982-2001/2002. Statistical prediction was performed for 21 winters of 1981/1982-2001/2002 in a cross-validated way and for 11 winters of 1999/2000-2009/2010 in an independent verification. The first four observed modes of empirical orthogonal function analysis of DJF TS variability explain 69 % of the total variability and are statistically separated from other higher modes. We identify these as predictable modes, because they have clear physical meaning and the MME reproduces them with acceptable criteria. The MME skill basically originates from the models' ability to capture the predictable modes. The MME shows better skill for the first mode, represented by a basin-wide warming trend, and for second mode related to the Arctic Oscillation. However, the statistical model better captures the third and fourth modes, which are strongly related to El Niño and Southern Oscillation (ENSO) variability on interannual and interdecadal timescales, respectively. Independent statistical forecasting for the recent 11-year period further reveals that the first and fourth modes are highly predictable. The second and third modes are less predictable due to lower persistence of boundary forcing and reduced potential predictability during the recent years. In particular, the notable decadal change in the monsoon-ENSO relationship makes the statistical forecast difficult. © 2012 The Author(s).

Jung S.,Seoul National University | Kim J.H.,Pusan National University | Kim J.,Seoul National University | Choi S.,Seoul National University | And 4 more authors.
Advanced Materials | Year: 2014

A novel method to produce porous pressure-sensitive rubber is developed. For the controlled size distribution of embedded micropores, solution-based procedures using reverse micelles are adopted. The piezosensitivity of the pressure sensitive rubber is significantly increased by introducing micropores. Using this method, wearable human-machine interfaces are fabricated, which can be applied to the remote control of a robot. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Park M.-H.,Soongsil University | Park Y.-H.,Seoul National University | Jeong H.-Y.,Pusan National University | Seo S.-W.,Seoul National University
IEEE Transactions on Mobile Computing | Year: 2013

With the emergence of diverse group-based services, multiple multicast groups are likely to coexist in a single network, and users may subscribe to multiple groups simultaneously. However, the existing group key management (GKM) schemes, aiming to secure communication within a single group, are not suitable in multiple multicast group environments because of inefficient use of keys, and much larger rekeying overheads. In this paper, we propose a new GKM scheme for multiple multicast groups, called the master-key-encryption-based multiple group key management (MKE-MGKM) scheme. The MKE-MGKM scheme exploits asymmetric keys, i.e., a master key and multiple slave keys, which are generated from the proposed master key encryption (MKE) algorithm and is used for efficient distribution of the group key. It alleviates the rekeying overhead by using the asymmetry of the master and slave keys, i.e., even if one of the slave keys is updated, the remaining ones can still be unchanged by modifying only the master key. Through numerical analysis and simulations, it is shown that the MKE-MGKM scheme can reduce the storage overhead of a key distribution center (KDC) by 75 percent and the storage overhead of a user by up to 85 percent, and 60 percent of the communication overhead at most, compared to the existing schemes. © 2002-2012 IEEE.

Kang H.,Pusan National University | Edmon P.P.,University of Manitoba | Jones T.W.,University of Minnesota
Astrophysical Journal | Year: 2012

We calculate nonthermal radiation from cosmic-ray (CR) protons and electrons accelerated at CR modified plane and spherical shocks, using time-dependent, diffusive shock acceleration (DSA) simulations that include radiative losses of CR electrons. Strong non-relativistic shocks with physical parameters relevant for young supernova remnants (SNRs) are considered in both the plane-parallel and spherically symmetric geometries, and compared at times when their dynamical and CR properties are concordant. A thermal leakage injection model and a Bohm-like diffusion coefficient are adopted. After DSA energy gains balance radiative losses, the electron spectrum at the plane shock approaches a time-asymptotic spectrum with a super-exponential cutoff above the equilibrium momentum. The postshock electron spectrum cuts off at a progressively lower momentum downstream from the shock due to the energy losses. That results in the steepening of the volume integrated electron energy spectrum by one power of the particle energy. These features evolve toward lower energies in the spherical, SNR shocks. In a CR modified shock, pion decay gamma-ray emission reveals distinct signatures of nonlinear DSA due to the concave proton momentum spectrum. Although the electron momentum spectrum has a much weaker concavity, the synchrotron spectral slope at the shock may flatten by about 0.1-0.3 between radio and X-ray bands. The slope of the volume integrated emission spectrum behaves nonlinearly around the break frequency. © 2012. The American Astronomical Society. All rights reserved.

Joo M.,Pusan National University | Sadikot R.T.,Jesse Brown VA Hospital | Sadikot R.T.,University of Illinois at Chicago
Mediators of Inflammation | Year: 2012

PGD2 is formed from arachidonic acid by successive enzyme reactions: oxygenation of arachidonic acid to PGH2, a common precursor of various prostanoids, catalyzed by cyclooxygenase, and isomerization of PGH2 to PGD2 by PGD synthases (PGDSs). PGD2 can be either pro- or anti-inflammatory depending on disease process and etiology. The anti-inflammatory and immunomodulatory attributes of PGDS/PGD2 provide opportunities for development of novel therapeutic approaches for resistant infections and refractory inflammatory diseases. This paper highlights the role of PGD synthases and PGD2 in immune inflammatory response. © 2012 Myungsoo Joo and Ruxana T. Sadikot.

Koh I.J.,Uijeongbu St Marys Hospital | Koh I.J.,Catholic University of Korea | Kim T.K.,Seoul National University | Chang C.B.,Seoul National University | And 2 more authors.
Clinical Orthopaedics and Related Research | Year: 2013

Background: The use of total knee arthroplasty (TKA) has increased substantially in most Western countries. However, the trends in TKA use and changes in demographic characteristics of patients having TKA in Korea remain unclear. Questions/purposes: We documented the trends in TKA use and in the demographics of patients undergoing TKA in Korea over the past decade and determined whether current TKA use in Korea corresponds to worldwide trends. Methods: Using the Health Insurance Review and Assessment Service of Korea database, we analyzed TKA records (n = 398,218) from 2001 to 2010 in Korea. Trends in TKA use and demographics, including numbers and rates of primary and revision TKA, growth rate and the revision burden, and age- and sex-specific rates, were estimated. They were compared with nationwide TKA registry reports from other countries, and a systematic review was performed. Results: Over the past decade, the primary and revision TKA rates increased by 407% and 267%, respectively. However, the revision burden remained 2%. The highest proportion was observed in 65 to 74 years old and the greatest increase in 75 to 84 years old, but a decrease was observed in those 55 to 64 years old. Women consistently had a ninefold higher TKA rate. The primary TKA rate was comparable with that of other countries, but the revision burden remained lower. In addition, old and female patients comprised considerably higher proportions in Korea. Conclusions: During the past decade, TKA use in Korea has markedly increased and caught up with the use levels of most developed Western countries. Trends toward consistent growth in elderly patients and higher rates in females were observed. Appropriate healthcare strategies reflecting these trends in demographics are urgently needed in Korea. © 2012 The Association of Bone and Joint Surgeons®.

Kang H.,Pusan National University | Jones T.W.,University of Minnesota | Edmon P.P.,Harvard University
Astrophysical Journal | Year: 2013

We explore nonlinear effects of wave-particle interactions on the diffusive shock acceleration (DSA) process in Type Ia-like supernova remnant (SNR) blast waves by implementing phenomenological models for magnetic field amplification (MFA), Alfvénic drift, and particle escape in time-dependent numerical simulations of nonlinear DSA. For typical SNR parameters, the cosmic-ray (CR) protons can be accelerated to PeV energies only if the region of amplified field ahead of the shock is extensive enough to contain the diffusion lengths of the particles of interest. Even with the help of Alfvénic drift, it remains somewhat challenging to construct a nonlinear DSA model for SNRs in which of the order of 10% of the supernova explosion energy is converted into CR energy and the magnetic field is amplified by a factor of 10 or so in the shock precursor, while, at the same time, the energy spectrum of PeV protons is steeper than E -2. To explore the influence of these physical effects on observed SNR emission, we also compute the resulting radio-to-gamma-ray spectra. Nonthermal emission spectra, especially in X-ray and gamma-ray bands, depend on the time-dependent evolution of the CR injection process, MFA, and particle escape, as well as the shock dynamic evolution. This result comes from the fact that the high-energy end of the CR spectrum is composed of particles that are injected in the very early stages of the blast wave evolution. Thus, it is crucial to better understand the plasma wave-particle interactions associated with collisionless shocks in detailed modeling of nonthermal radiation from SNRs. © 2013. The American Astronomical Society. All rights reserved.

Jung H.-R.,Pusan National University | Kim E.-J.,Pusan National University | Park Y.J.,Korea Atomic Energy Research Institute | Shin H.-C.,Pusan National University
Journal of Power Sources | Year: 2011

Nickel-tin foams with a graded micro-porous framework and nano-porous walls are created by an electrochemical deposition method for use as the anode in rechargeable lithium batteries. The resulting electrodes react readily with lithium electrochemically and deliver a reversible capacity of more than 470 mAh g-1 for up to 50 cycles. In addition, they show outstanding rate performance: their reversible capacity at a discharging rate of 20 C is about 70% of the capacity at a rate of 1 C, due mainly to their unique structure which allows facile lithium-ion transport and fast surface reactions. The reversible capacity and rate capability show strong dependence on the thickness of the deposit and this is associated with the accessibility of lithium ions inside the porous structure. © 2011 Elsevier B.V.

Kim J.,Korea Atomic Energy Research Institute | Jeong J.J.,Pusan National University
Numerical Heat Transfer; Part A: Applications | Year: 2012

A large eddy simulation at the conditions of experiments by Vattenfall [1] was performed in order to investigate the phenomenon of turbulent mixing affecting the thermal fatigue in a T-junction. In the present LES based on the dynamic Vreman model, mean velocity, turbulence intensity, and Reynolds shear stress profiles show good agreement with those measured in the Vattenfall experiment. With the present LES results verified, the characteristics of vortical structures in terms of turbulent mixing resulting in thermal fatigue was investigated. The energy spectra are shown to have a dominant frequency of around St=0.5 agreeing with the value reported in experiments. On the other hand, the dominant frequency near the wall is different from that reported at the centerline (St∼1), meaning that the thermal fatigue may not result from the wake structure, and is affected by the vortical structures existing near the wall. This result is consistent with one stated by Muramatsu [2] that the frequency characteristics near the wall are closely associated with arched vortices. In addition, the present LES results are used to provide useful insights in predicting this kind of flow using RANS computations. © 2012 Copyright Taylor and Francis Group, LLC.

Song S.-H.,U.S. National Institute of Diabetes and Digestive and Kidney Diseases | Kim A.,Pusan National University | Ragoczy T.,Fred Hutchinson Cancer Research Center | Bender M.A.,University of Washington | And 2 more authors.
Blood | Year: 2010

Ldb1 and erythroid partners SCL, GATA-1, and LMO2 form a complex that is required to establish spatial proximity between the β-globin locus control region and gene and for transcription activation during erythroid differentiation. Here we show that Ldb1 controls gene expression at multiple levels. Ldb1 stabilizes its erythroid complex partners on β-globin chromatin, even though it is not one of the DNA-binding components. In addition, Ldb1 is necessary for enrichment of key transcriptional components in the locus, including P-TEFb, which phosphorylates Ser2 of the RNA polymerase C-terminal domain for efficient elongation. Furthermore, reduction of Ldb1 results in the inability of the locus to migrate away from the nuclear periphery, which is necessary to achieve robust transcription of β-globin in nuclear transcription factories. Ldb1 contributes these critical functions at both embryonic and adult stages of globin gene expression. These results implicate Ldb1 as a factor that facilitates nuclear relocation for transcription activation. © 2010 by The American Society of Hematology.

Cho H.-M.,Pusan National University | Park Y.J.,Korea Atomic Energy Research Institute | Shin H.-C.,Pusan National University
Journal of the Electrochemical Society | Year: 2010

A systematic semiempirical way to analyze the variation in dc polarization with the operating time of electrochemical energy conversion devices is suggested. This includes the differentiation of the constituents of the total cell impedance, followed by the estimation of the time-dependent elementary contributions to the total polarization with the help of the theoretical analysis of an equivalent circuit. This unique method enables us to design high power energy conversion devices and, at the same time, effectively diagnose the power degradation of a cell. A comparative analysis of a fresh cell with an aged cell and the effect of temperature on polarization are exemplified. In particular, time-dependent contributions of elementary polarizations have been quantitatively suggested in each case with a strategy for the design of the materials. From this approach, power degradation after repeated battery cycling was ascribed to a rise in polarization due to the interfacial charge-transfer resistance of the cathode. Furthermore, the charge-transfer resistance of the cathode proved to be the most important factor in high rate battery discharging at ambient and low operating temperatures. © 2009 The Electrochemical Society.

Kim J.H.,Pusan National University | Chung K.,Seoul National University
International Journal of Plasticity | Year: 2015

Thin multilayered structures with glass substrates are widely used in electronic devices. When layers having different thermal or mechanical properties are subjected to processes with temperature variations, warpage and residual stresses may develop incurred by the mismatch of volume change, possibly leading to the failure of the device. In order to analyze the thermo-mechanical behavior of glass including the warpage in multilayered structures with glass substrates, the thermo-mechanical constitutive equations of glass are developed here by coupling the stress relaxation (for mechanical behavior) and structural relaxation models (for thermal behavior). The constitutive equations for structural relaxation are generalized for the case with temperature dependent thermal expansion coefficients, while considering both formulations based on the specific volume and the fictive temperature. Besides, the numerical formulations of the constitutive equations for finite element analysis are derived for three-dimensional and plane stress conditions. The developed constitutive model is validated with experiments for the warpage of silicon-glass multilayered structures undergoing thermal cycles. © 2015 Elsevier Ltd.

Lee E.-J.,Pusan National University | Ha K.-J.,Pusan National University | Jhun J.-G.,Seoul National University
Climate Dynamics | Year: 2014

The interdecadal and the interannual variability of the global monsoon (GM) precipitation over the area which is chosen by the definition of Wang and Ding (Geophys Res Lett 33: L06711, 2006) are investigated. The recent increase of the GM precipitation shown in previous studies is in fact dominant during local summer. It is evident that the GM monsoon precipitation has been increasing associated with the positive phase of the interdecadal Pacific oscillation in recent decades. Against the increasing trend of the GM summer precipitation in the Northern Hemisphere, its interannual variability has been weakened. The significant change-point for the weakening is detected around 1993. The recent weakening of the interannual variability is related to the interdecadal changes in interrelationship among the GM subcomponents around 1993. During P1 (1979-1993) there is no significant interrelationship among GM subcomponents. On the other hand, there are significant interrelationships among the Asian, North American, and North African summer monsoon precipitations during P2 (1994-2009). It is noted that the action center of the interdecadal changes is the Asian summer (AS) monsoon system. It is found that during P2 the Western North Pacific summer monsoon (WNPSM)-related variability is dominant but during P1 the ENSO-related variability is dominant over the AS monsoon region. The WNPSM-related variability is rather related to central-Pacific (CP) type ENSO rather than the eastern-Pacific (EP) type ENSO. Model experiments confirm that the CP type ENSO forcing is related to the dominant WNPSM-related variability and can be responsible for the significant interrelationship among GM subcomponents. © 2013 Springer-Verlag Berlin Heidelberg.

Kim T.,Seoul National University | Kang J.,Seoul National University | Lee J.-H.,Pusan National University | Yoon J.,Seoul National University
Water Research | Year: 2011

Development of an effective strategy for biofilm control in water-related system has become a matter of significant concern nowadays. Electrochemical monitoring, especially electrochemical impedance spectroscopy (EIS), is one of the efficient approaches to dealing with biofilm-related issues. However, currently used EIS methods without a redox probe intend to detect all effects generated from media components, bacteria, and bacterial metabolites, which used to make the signals from the attached bacteria and biofilm weakened. In this study, we tried improved EIS measurement to monitor bacterial adhesion and biofilm maturation using a double-layer capacitance. In this improved method, we minimized background signal by subtracting the interference of electrolyte caused by bacterial metabolism. Pseudomonas aeruginosa PA14 wild type and wspF mutant that form the biofilm of distinct nature were used for the model strains to test our method. During bacterial adhesion and biofilm maturation, EIS data were collected and equivalent circuit analysis was carried out to obtain constant phase element (CPE) values representing double-layer capacitance. Since the influence by the bacterial growth-related culture media condition was eliminated by adopting fresh electrolyte at the measurement, the contribution of attached bacteria and biofilm was exclusively measured. As a result, the bacterial adhesion at the early stage of biofilm development was specifically monitored from reduction in double-layer capacitance. Particularly, the plateau in double-layer capacitance appeared upon biofilm maturation, indicating that biofilm maturation could be expected beyond this point. In conclusion, this study found that measurement of double-layer capacitance based on EIS could provide a monitoring parameter suggesting bacterial adhesion and the initiation point of biofilm maturation. © 2011 Elsevier Ltd.

Kwon K.,Samsung | Nam I.,Pusan National University
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

In this paper, a linearization technique for a transconductor using vertical NPN (V-NPN) bipolar junction transistors (BJTs) in a deep n-well CMOS process is proposed to achieve high linearity performance without degrading power efficiency and noise performance. The proposed transconductor consists of a V-NPN BJT pseudodifferential transconductor (PDT) and a V-NPN BJT fully differential transconductor (FDT). The linearity of the proposed transconductor is improved by canceling the negative peak value of gm′′ in the FDT with the positive one in the PDT and by making overall gm ′′ of the proposed transconductor close to zero. To verify the proposed linearization method, an RF amplifier and a first-order Gm-C low-pass filter adopting the proposed transconductor are designed and implemented in a 0.18-μm deep n-well CMOS process. The implemented RF amplifier and Gm-C low-pass filter achieve 5.8-and 8.5-dB improvements over conventional circuits in the output-referred third-order intercept point, respectively. © 1963-2012 IEEE.

An J.H.,Seoul National University | Goo E.,Seoul National University | Kim H.,Seoul National University | Seo Y.-S.,Pusan National University | Hwang I.,Seoul National University
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) controls the production of numerous intra- and extracellular products across many species of Proteobacteria. Although these cooperative activities are often costly at an individual level, they provide significant benefits to the group. Other potential roles for QS include the restriction of nutrient acquisition and maintenance of metabolic homeostasis of individual cells in a crowded but cooperative population. Under crowded conditions, QS may function to modulate and coordinate nutrient utilization and the homeostatic primary metabolism of individual cells. Here, we show that QS down-regulates glucose uptake, substrate level and oxidative phosphorylation, and de novo nucleotide biosynthesis via the activity of the QS-dependent transcriptional regulator QsmR (quorum sensing master regulator R) in the rice pathogen Burkholderia glumae. Systematic analysis of glucose uptake and core primary metabolite levels showed that QS deficiency perturbed nutrient acquisition, and energy and nucleotide metabolism, of individuals within the group. The QS mutants grew more rapidly than the wild type at the early exponential stage and outcompeted wild-type cells in coculture. Metabolic slowing of individuals in a QS-dependent manner indicates that QS acts as a metabolic brake on individuals when cells begin to mass, implying a mechanism by which AHL-mediated QS might have evolved to ensure homeostasis of the primary metabolism of individuals under crowded conditions. © 2014, National Academy of Sciences. All rights reserved.

Lim H.T.,Seoul National University | Ahn K.H.,Seoul National University | Hong J.S.,Soongsil University | Hyun K.,Pusan National University
Journal of Rheology | Year: 2013

In this study, the nonlinear response of polymer nanocomposites under large amplitude oscillatory shear (LAOS) flow was investigated. We first investigated polycaprolactone (PCL)/multiwall nanotube (MWNT) composites under LAOS flow using different analyzing methods including Lissajous plot analysis, stress decomposition, and Fourier transform rheology (FT-rheology). The nonlinear parameter Q ( I3 / 1 / γ02) was obtained from the FT-rheology as a function of strain amplitude, and the zero-strain nonlinearity Q0 ( limγ0→ 0 Q) was also calculated. We compared the linear and nonlinear viscoelastic properties as we increase MWNT concentration. It was found that the zero-strain nonlinearity (Q0) was more sensitive to detect the effect of MWNT concentration than the linear viscoelastic properties. We also investigated the effect of particle shape on nonlinear viscoelastic properties of the polymer composites containing particles of different shape, e.g., PCL/MWNT (one-dimensional thread shape), PCL/organomodified montmorillonite (two-dimensional plate shape), PCL/precipitated calcium carbonate (three-dimensional cubic shape). Furthermore, we introduced a new parameter, nonlinear-linear viscoelastic ratio, to compare linear and nonlinear viscoelasticity. © 2013 The Society of Rheology.

Feng X.,Pusan National University | Moon I.,Seoul National University | Ryu K.,Pusan National University
International Journal of Production Economics | Year: 2014

Revenue-sharing (RS) contracts have been used in a number of industries and have proven to be effective. However, the current RS contracts can be limited when improving the supply chain performance because of member reliability issues. This paper studies a revenue-sharing with reliability (RSR) contract in an N-stage supply chain. In this type of supply chain, there are more than two stages, and certain members have more than one upstream member. First, we propose an RSR contract that can coordinate supply chains and arbitrarily allocate total profits. A two-round profit allocation mechanism is utilized in this RSR contract. In the first round, an initial profit allocation scenario is decided; in the second round, the allocation is adjusted by considering the reliability of all of the members. A flexible method for adjusting the profits in the second round is proposed. Second, we study the incentives for the members to improve their reliability under the RS and RSR contracts by considering two realistic types of improvement investments in reliability. It is found that, in some cases, the RS contracts are limited in terms of encouraging the members to improve their reliability. Next, we show that there are greater incentives for members to improve their reliability under an RSR contract. We discuss in what cases the maximum possible profit of the supply chain under the RSR contract is higher than under the RS contract. Our analytical and numerical results yield insights into how managers can be encouraged to improve their reliability by setting certain decision variables. © 2013 Elsevier B.V.

Sarkar B.,Pusan National University | Sarkar B.,Vidyasagar University | Moon I.,Seoul National University
International Journal of Production Economics | Year: 2014

This paper illustrates the relationship between quality improvement, reorder point, and lead time, as affected by backorder rate, in an imperfect production process. To reduce the total system cost by optimizing the setup cost, lot size, lead time, reorder point, and process quality parameter simultaneously, we first consider that the lead time demand follows a normal distribution, then we apply the distribution free approach for the lead time demand. We prove two lemmas which are used to find optimal solutions for the basic and distribution free models. We compare our models with the existing models using numerical examples and show that significant savings over the existing models can be achieved. © 2014 Elsevier B.V. All rights reserved.

Pusan National University and Samsung | Date: 2012-07-30

A liquid crystal display is provided. A liquid crystal display according to an exemplary embodiment of the present invention includes a first substrate, a second substrate facing the first substrate, and a liquid crystal layer interposed between the first substrate and the second substrate, wherein the liquid crystal layer includes liquid crystal molecules and nanoparticles including a hydrophobic group having a chain structure and a hydrophilic group.

Pusan National University and Samsung | Date: 2013-09-05

Provided are a compound of Formula 1 and an organic light-emitting device including the compound. Descriptions of substituents of the Formula 1 are referred to in the detailed description.

Pusan National University and Samsung | Date: 2013-01-08

Provided is a distributed parallel simulation method. In the method, a plurality of local simulations is executed in parallel for a plurality of local design objects, respectively. The local design objects are included in a model at a specific abstraction level and are spatially distributed. At least one actual output is generated using at least one of the local design objects in a current local simulation of the plurality of local simulations. At least one expected output and the at least one actual output in the current local simulation are compared. Values of the at least one actual output and position information of the values from the current local simulation are transmitted to at least one remaining local simulation of the plurality of local simulations in response to a determination from the comparison that a difference exists between the at least one expected output and the at least one actual output.

Pusan National University and Samsung | Date: 2011-11-01

A transflective liquid crystal display includes a liquid crystal panel including a first substrate, a second substrate, a liquid crystal layer, the first and second substrates arranged to face each other and the liquid crystal layer between the first and second substrates, a reflection polarizer and an absorption polarizer at opposing outer sides of the liquid crystal panel, and a backlight unit at an outer side of the liquid crystal panel and supplying light to the inside of the liquid crystal panel. A reflective axis of the reflection polarizer is parallel with a transmissive axis of the absorption polarizer, the transmissive axis of the reflection polarizer perpendicularly crosses the transmissive axis of the absorption polarize, and the liquid crystal layer includes liquid crystal molecules and a dichroic dye.

Samsung and Pusan National University | Date: 2014-07-24

A novel organic compound and an organic light emitting diode device using the same. The organic compound is represented by Chemical Formula 1: The organic compounds can provide improved electrical stability, high charge transport capability, a high glass transition temperature and may be capable of preventing crystallization. Also disclosed is an organic light emitting diode device including the compound of Chemical Formula 1 in the organic layer.

Pusan National University and Samsung | Date: 2013-09-25

Provided are a compound of Formula 1 and an organic light-emitting device including the compound of Formula 1: The compounds of Formula 1 are particularly useful as fluorescent dopants in the emission layer of the organic light-emitting device.

Electronics, Telecommunications Research Institute and Pusan National University | Date: 2010-11-17

Provided is an environmental gas sensor including an insulating substrate, a metal electrode formed above the insulating substrate, and a sensing layer formed of a semiconductor oxide nanofiber-nanorod hybrid structure above the metal electrode. The environmental gas sensor can have excellent characteristics of ultra high sensitivity, high selectivity, high responsiveness and low power consumption by forming a semiconductor oxide nanorod having high sensitivity to a specific gas on a semiconductor oxide nanofiber.

Samsung and Pusan National University | Date: 2014-07-14

A compound for an organic light emitting device is represented by Chemical Formula 1. An organic light emitting device includes a first electrode, a second electrode facing the first electrode and an organic layer between the first electrode and the second electrode, and the organic layer includes a compound represented by Chemical Formula 1. In the above Chemical Formula 1, Ar and L are the same as defined in the specification.

Samsung and Pusan National University | Date: 2015-11-23

Provided is a liquid crystal device including a first substrate, a lower electrode, a lower pattern electrode, a second substrate facing the first substrate, an upper electrode, and a liquid crystal layer. The lower electrode is disposed on the first substrate. The lower pattern electrode is insulated from the lower electrode and disposed on the lower electrode, and the lower pattern electrode includes branch parts. The upper electrode is disposed on the second substrate. The liquid crystal layer is disposed between the first substrate and the second substrate, and the liquid crystal layer includes liquid crystal molecules having negative dielectric anisotropy.

Samsung and Pusan National University | Date: 2014-05-28

An organic light-emitting device including an iridium complex represented by Formula 1:

Pusan National University and Samsung | Date: 2013-04-02

A method for forming a display device includes forming a liquid crystal layer between a first substrate and a second substrate spaced apart from the first substrate, in which the liquid crystal layer includes a liquid crystal composition including a reactive mesogen, applying an electric field to the liquid crystal layer, firstly curing the liquid crystal layer at a temperature from about 20 C. to about 60 C., and secondly curing the liquid crystal layer without applying the electric field. The liquid crystal composition includes the reactive mesogen in an amount exceeding 0 percent by weight and equal to or smaller than about 30 percent by weight relative to a total weight of the liquid crystal composition.

Samsung and Pusan National University | Date: 2014-07-22

A condensed cyclic compound is represented by Formula 1. An organic light-emitting device includes the condensed cyclic compound represented by Formula 1. X, Y_(1), Y_(2), A, B, and R_(1 )of Formula 1 are described herein. An organic light-emitting device including an organic layer including the condensed cyclic compound may have low driving voltage, high efficiency, high brightness, and long lifespan.

Pusan National University and Samsung | Date: 2013-05-29

A method of calibrating a first threshold voltage that is a reference of X-ray detection for each unit cell of a plurality of unit cells of an X-ray detector may comprise detecting an X-ray by using a plurality of second threshold voltages for each of a plurality of X-rays having spectra at different energy levels; determining a correspondence relationship between energies having a maximum intensity in the spectra of X-rays and third threshold voltages at which a maximum number of photons having a same energy intensity are detected; and/or calibrating the first threshold voltage based on the determined correspondence relationship.

Pusan National University and Samsung | Date: 2013-10-17

Provided are an iridium complex represented by Formula 1 below and an organic light-emitting device including the same. Descriptions of substituents of Formula 1 are the same as described in the detailed description of the present specification.

Pusan National University and Samsung | Date: 2013-10-28

An organometallic compound represented by Formula 1 below is disclosed. An organic light-emitting device including at least one organometallic compound represented by Formula 1 is also disclosed.

Pusan National University and Samsung | Date: 2014-01-29

A heterocyclic compound, an organic light-emitting device, and a flat panel display apparatus, the compound being represented by Formula 1, below:

Samsung and Pusan National University | Date: 2014-07-28

A condensed cyclic compound is represented by Formula 1, and an organic light-emitting device includes the condensed cyclic compound. The organic light-emitting device includes a first electrode, a second electrode facing the first electrode, and an organic layer. The organic layer includes an emission layer and the condensed-cyclic compound.

Seo J.H.,Pusan National University | Kim T.-W.,Seoul National University | Weinreb R.N.,University of California at San Diego
Investigative Ophthalmology and Visual Science | Year: 2014

Purpose. To investigate the characteristics of the lamina cribrosa (LC) depth in healthy eyes using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT). Methods. Serial horizontal B-scans of the optic nerve head were obtained using EDI SD-OCT for both eyes of 150 healthy subjects. Anterior LC surface (ALCS) depths were measured with B-scan images from equidistant planes in each eye and defined as the distance from the Bruch's membrane opening plane to the anterior LC surface. The ALCS depths were compared between eyes within each subject. A linear mixed model was used to identify factors associated with the ALCS depth. Results. The average ALCS depth was 402.06 ± 101.46 μm (range, 193.08-826.81). The ALCS depth was not significantly different between the right and left eyes (Ps > 0.05 at all planes). There was a strong intereye correlation within subjects (Rs ≥ 0.808 at all planes, Ps < 0.0001 at all planes). The ALCS depth was largest in the superior periphery and smallest in the central inferior plane. ALCS depth was larger in males (P < 0.05) and also larger in eyes with shorter axial length (P = 0.029). Conclusions. This study reports the range of ALCS depth in healthy subjects. These data suggest that ALCS depth is related to sex and axial length. © 2014 The Association for Research in Vision and Ophthalmology, Inc.

Moon I.,Pusan National University | Lee J.-H.,Electronics and Telecommunications Research Institute | Seong J.,Sejong Industrial Co.
Expert Systems with Applications | Year: 2012

The vehicle routing problem with time windows (VRPTW) is an important problem in third-party logistics and supply chain management. We extend the VRPTW to the VRPTW with overtime and outsourcing vehicles (VRPTWOV), which allows overtime for drivers and the possibility of using outsourced vehicles. This problem can be applied to third-party logistics companies for managing central distributor-local distributors, local distributor-retailers (or customers), and manufacturers. We developed a mixed integer programming model, a genetic algorithm (GA), and a hybrid algorithm based on simulated annealing. The computational results demonstrate the efficiency of the developed algorithms. We also develop a decision support system for the VRPTWOV that is equipped with a vehicle route rescheduling function for realistic situations based on the GA. © 2012 Elsevier Ltd. All rights reserved.

Samsung and Pusan National University | Date: 2014-11-21

A display device includes: a first substrate; a second substrate disposed opposite to the first substrate; a first electrode and a second electrode disposed on the first substrate; a third electrode and a fourth electrode disposed on the second substrate; and a liquid crystal layer injected between the first substrate and the second substrate and including a plurality of liquid crystal molecules, where the second electrode extends substantially in a first direction, the third electrode extends substantially in a second direction, and the first direction and the second direction are perpendicular to each other.

Samsung and Pusan National University | Date: 2015-01-14

An organic light-emitting device includes a first electrode, a second electrode, and an organic layer between the first electrode and the second electrode and including at least one condensed cyclic compound represented by Formula 1: The organic light-emitting device including the condensed cyclic compound represented by Formula 1 may have low driving voltage, high efficiency, high brightness, and long lifespan.

Electronics, Telecommunications Research Institute and Pusan National University | Date: 2015-06-04

Provided is an apparatus for blood analysis. The apparatus for blood analysis includes a spin coater to which blood is supplied, a light source part emitting light onto the spin coater, a measurement part detecting light reflected from the blood on the spin coater, and outputting a detected signal, and an analysis part analyzing information on the blood from the detected signal from the measurement part.

Electronics, Telecommunications Research Institute and Pusan National University | Date: 2014-06-06

The present invention relates to a core-shell nanoparticle, a method of fabricating the same and a gas sensor using the same, more particularly to a core-shell nanoparticle which includes a core including a first metal oxide and a shell including a second metal oxide, the first metal oxide and the second metal oxide being oxides of the same metal having different oxidation states, a method of fabricating the same and a gas sensor using the same.

Pusan National University and Samsung | Date: 2014-04-03

A method of driving a display panel includes applying a common voltage and a bias voltage to two of a first electrode, a second electrode and a third electrode of the display panel to form a vertical field during a period during which the display panel displays an image, and applying a data voltage based on a grayscale of the image to one of the first and second electrodes to form an in-plane field during the period during which the display panel displays the image, where the display panel includes a first substrate including the first electrode, the second electrode which overlaps the first electrode and a transistor connected to one of the first and second electrodes, and a second substrate disposed opposite to the first substrate and including the third electrode.

A liquid crystal display panel includes a lower substrate, an upper substrate and a liquid crystal layer. The lower substrate includes a first base substrate and a pixel electrode formed on the first base substrate. The first base substrate includes a first sub pixel area and a second sub pixel area. The upper substrate includes a second base substrate and a common electrode formed on the second base substrate. The liquid crystal layer is interposed between the lower substrate and the upper substrate, and includes a first polymer disposed in the first sub pixel area and a second polymer disposed in the second pixel area. The first polymer has a first pre-tilt, and the second polymer has a second pre-tilt different from the first pre-tilt. Thus, a display quality of a liquid crystal display apparatus including the liquid crystal display panel may be enhanced.

Kawano M.,Kagoshima University | Hwang J.,Pusan National University
Applied Clay Science | Year: 2011

Organic molecules secreted by bacterial cells are capable of influencing dissolution and precipitation rates of various minerals including calcium carbonate (CaCO 3) minerals. To evaluate the effects of polysaccharides on the precipitation rates and polymorph of CaCO 3 minerals, precipitation experiments were performed in systems containing alginic acid or gellan gum by the batch method using 100ml solution at 25°C. Each solution contained 5.0mM Ca 2+ and Mg 2+, and 20.0mM HCO 3 - ions with 0.00, 0.01, 0.05, 0.1, 0.2, and 0.5mg/ml of alginic acid (A systems: A1-A5) or gellan gum (G systems: G1-G5). Results showed that both alginic acid and gellan gum significantly inhibited the precipitation of CaCO 3 minerals with increasing concentrations of the polysaccharides. Notably, it was found that the inhibition effect of alginic acid was much greater than that of gellan gum. In addition, only aragonite was formed in solutions containing no polysaccharides, owing to the effect of Mg 2+ ions. However, the dominance of aragonite as a polymorph decreased and that of calcite increased with increasing concentrations of both polysaccharides, and this effect on the polymorph was much greater for alginic acid than for gellan gum. These effects on precipitation rates and polymorph are likely caused by the adsorption of both polysaccharides on the surfaces of calcite and aragonite. However the higher charge density of alginic acid may have contributed to the stronger inhibition effects on precipitation rates, and relatively higher adsorption affinity of the aragonite surfaces with the polysaccharides also inhibits growth of aragonite resulting in formation of calcite as a dominant polymorph. © 2011 Elsevier B.V.

Annamalai H.,University of Hawaii at Manoa | Hafner J.,University of Hawaii at Manoa | Sooraj K.P.,University of Hawaii at Manoa | Sooraj K.P.,Pusan National University | And 2 more authors.
Journal of Climate | Year: 2013

Monsoon rainfall over South Asia has decreased during the last 5 to 6 decades according to several sets of observations. Although sea surface temperature (SST) has risen across the Indo-Pacific warm pool during this period, the expected accompanying increased rainfall has occurred only in the tropical western Pacific. The above changes noted in observations are also seen in a coupled climate model, but only when the model includes the recent increase in greenhouse gas concentration. The hypothesis that the robust rise in SST over the warm pool, perhaps anchored by an increase in greenhouse gas concentrations, is instrumental in the east- west shift in monsoon rainfall (enhanced rainfall over tropical western Pacific and decreased rainfall over South Asia) is proposed.Asuite of controlled experiments with an atmospheric general circulation model has been performed to isolate the impact of regional SST warming trends on the dryness over South Asia. Model experiments support the hypothesis that the rising SST trend over the tropical western Pacific has changed the atmospheric circulation: over the Bay of Bengal more dry and cool air is advected from the northeast than previously. Moist static energy budget diagnostics on the model solutions identify the sources for this east- west shift. SST warming over the warm pool has accelerated in recent decades. Therefore, a close monitoring of that warming is important for long-term variations of monsoon rainfall. The inconsistency in the amplitude of drying over South Asia among the various land-based rainfall observations and lack of sustained rainfall observations over the open oceans, however, poses constraints in the results. © 2013 American Meteorological Society.

Noh K.T.,Korea University | Park Y.-M.,Pusan National University | Cho S.-G.,Konkuk University | Choi E.-J.,Korea University
Experimental Cell Research | Year: 2011

Glycogen synthase kinase-3β (GSK-3β), a multifunctional kinase, is a regulator of lipopolysaccharide (LPS)-mediated septic shock. Apoptosis signal-regulating kinase 1 (ASK1) is also required for LPS-induced activation of p38, which is a crucial determinant for the production of pro-inflammatory cytokines via Toll-like receptor 4 (TLR4) in endotoxemia. Here, we show that attenuation of endotoxemia induced by GSK-3 inhibition is caused by the ASK1 reduction-mediated inhibition of p38, a representative downstream kinase of ASK1. LPS-stimulated activation of p38 was blocked by the reduction of ASK1 via the knockdown of GSK-3β In addition, compared with L929 control cells, ASK1 protein was reduced in L929 cells stably expressing Wnt-3a and in which β-catenin was active, due to the inhibition of GSK-3β activity. GSK-3β inhibition-mediated ASK1 reduction was also confirmed by reduced ASK1 in GSK-3β-deficient mouse embryo fibroblasts (MEFs) and MCF7 GSK-3β siRNA cells. Furthermore, ASK1 protein stability was also attenuated in MCF7 GSK-3β siRNA cells compared with GFP control cells. Consistent with stability data, a much stronger ubiquitination of ASK1 was observed in cells in which GSK-3β was knocked down. These findings suggest that GSK-3β crosstalks with p38 kinase via the regulation of ASK1 protein stability in endotoxemia. © 2011 Elsevier Inc.

Sim W.-J.,Pusan National University | Lee J.-W.,Pusan National University | Lee E.-S.,Pusan National University | Shin S.-K.,National Institute of Environmental Research | And 2 more authors.
Chemosphere | Year: 2011

Twenty-four pharmaceuticals were measured in wastewater from 12 municipal wastewater treatment plants (M-WWTPs), four livestock WWTPs (L-WWTPs), four hospital WWTPs (H-WWTPs) and four pharmaceutical manufacture WWTPs (P-WWTPs). The total concentration of pharmaceuticals in the influent samples was highest in the L-WWTPs followed by the P-WWTPs, H-WWTPs and M-WWTPs. The effluents had different patterns of pharmaceuticals than their corresponding influents because of the different fate of each compound in the WWTPs. Non-steroidal anti-inflammatory drugs (NSAIDs) were the most dominant in the influents from the M-WWTPs and P-WWTPs, while antibiotics were dominantly detected in the L-WWTP. In the H-WWTP influents, NSAIDs, caffeine and carbamazepine were dominant. In the P-WWTPs, the distribution of pharmaceuticals in the effluents varied with sampling sites and periods. The M-WWTP influents had the highest daily loads, while the effluents showed somewhat similar levels in all source types. © 2010 Elsevier Ltd.

Santosa H.,Pusan National University | Jiyoun Hong M.,Columbia University | Kim S.-P.,Korea University | Hong K.-S.,Pusan National University
Review of Scientific Instruments | Year: 2013

Functional near-infrared spectroscopy (fNIRS) is used to detect concentration changes of oxy-hemoglobin and deoxy-hemoglobin in the human brain. The main difficulty entailed in the analysis of fNIRS signals is the fact that the hemodynamic response to a specific neuronal activation is contaminated by physiological and instrument noises, motion artifacts, and other interferences. This paper proposes independent component analysis (ICA) as a means of identifying the original hemodynamic response in the presence of noises. The original hemodynamic response was reconstructed using the primary independent component (IC) and other, less-weighting-coefficient ICs. In order to generate experimental brain stimuli, arithmetic tasks were administered to eight volunteer subjects. The t-value of the reconstructed hemodynamic response was improved by using the ICs found in the measured data. The best t-value out of 16 low-pass-filtered signals was 37, and that of the reconstructed one was 51. Also, the average t-value of the eight subjects' reconstructed signals was 40, whereas that of all of their low-pass-filtered signals was only 20. Overall, the results showed the applicability of the ICA-based method to noise-contamination reduction in brain mapping. © 2013 AIP Publishing LLC.

Song S.-K.,Pusan National University | Shon Z.-H.,Dong - Eui University
Atmospheric Environment | Year: 2012

The emissions of greenhouse gases (GHGs) and air pollutants from aircraft in the boundary layer at four major international airports in Korea over a two-year period (2009-2010) were estimated using the Emissions and Dispersion Modeling System (EDMS) (i.e. activity-based (Landing/Take-Off (LTO) cycle) methodology). Both domestic and international LTOs and ground support equipment at the airports were considered. The average annual emissions of GHGs (CO 2, N 2O, CH 4 and H 2O) at all four airports during the study period were 1.11 × 10 3, 1.76 × 10 -2, -1.85 × 10 -3 and 3.84 × 10 8 kt yr -1, respectively. The emissions of air pollutants (NO x, CO, VOCs and particulate matter) were 5.20, 4.12, 7.46 × 10 -1 and 3.37 × 10 -2 kt yr -1, respectively. The negative CH 4 emission indicates the consumption of atmospheric CH 4 in the engine. The monthly and daily emissions of GHGs and air pollutants showed no significant variations at all airports examined. The emissions of GHGs and air pollutants for each aircraft operational mode differed considerably, with the largest emission observed in taxi-out mode. © 2012 Elsevier Ltd.

Jung D.H.,Pusan National University | Jeong H.M.,University of Ulsan | Kim B.K.,Pusan National University
Journal of Materials Chemistry | Year: 2010

Vinyltrimethoxysilane (VTMS)-modified silica particles were incorporated into the chain of amorphous polyurethane (PU) by covalent bonds, to synthesize an organic-inorganic hybrid material with an extremely long relaxation time. At 1% silica, the PU-silica chemical hybrids gave over 99% shape fixity and shape recovery with <2% hysteresis during the four thermomechanical cycles. As silica content increases (2, 3%) shape memory performance slightly decreased with repeated cycles. Results were favorably compared with PUs cross-linked by hydroxyl ethylacrylate (HEA) and VTMS, and physical blends with silica particles. The results were interpreted based on the triple effects of silica particles as multifunctional cross-linkers, reinforcing fillers, and relaxation retarders of the polymer chains during loading and unloading. © The Royal Society of Chemistry 2010.

Kim Y.,Doosan Heavy Industries and Construction | Cho J.,Korea University | Bae W.,Pusan National University
Journal of Materials Processing Technology | Year: 2011

The internal state of an ingot structure manufactured by the casting process has many loose structures. Generally, loose ingot structures make it difficult to obtain sound material properties. Unsound factors such as voids, porosity and shrinkage in the ingot can be improved by the forging process. The closing of the internal voids depends on the forging process. In this study, numerical analysis was carried out to find the upsetting and cogging processes increasing the internal forging effect of an ultra-large ingot (520 tons). Various parameters such as the ratio of height to diameter of ingot, shifting method, die staggering, and pressing depth were investigated. In addition, verification tests were performed visually using a 1/25 scale model test with pure lead. Results from the numerical analysis and the scaled-down model experiment were compared. The optimal forging process was applied to manufacture a mock-up product. An efficient forging process was suggested to improve the void closing and to achieve the uniform forging effect in the upsetting and cogging process of an ultra-large ingot. © 2011 Elsevier B.V. All rights reserved.

Jang T.S.,Pusan National University | Baek H.S.,Brown University | Paik J.K.,Pusan National University
International Journal of Non-Linear Mechanics | Year: 2011

The aim of this paper is to develop a new method of analyzing the non-linear deflection behavior of an infinite beam on a non-linear elastic foundation. Non-linear beam problems have traditionally been dealt with by semi-analytical approaches that involve small perturbations or by numerical methods, such as the non-linear finite element method. In this paper, in contrast, a transformed non-linear integral equation that governs non-linear beam deflection behavior is formulated to develop a new method for non-linear solutions. The proposed method requires an iteration to solve non-linear problems, but is fairly simple and straightforward to apply. It also converges quickly, whereas traditional non-linear solution procedures are generally quite complex in application. Mathematical analysis of the proposed method is performed. In addition, illustrative examples are presented to demonstrate the validity of the method developed in the present study. © 2010 Elsevier Ltd. All rights reserved.

Perry J.S.A.,U.S. National Institutes of Health | Han S.,U.S. National Institutes of Health | Han S.,Pusan National University | Xu Q.,U.S. National Institutes of Health | And 5 more authors.
Science Translational Medicine | Year: 2012

Genetic polymorphisms in the interleukin-2 receptor a (IL-2Rα) chain (CD25) locus are associated with several human autoimmune diseases, including multiple sclerosis (MS). Blockade of CD25 by the humanized monoclonal antibody daclizumab decreases MS-associated inflammation but has surprisingly limited direct inhibitory effects on activated T cells. The present study describes unexpected effects of daclizumab therapy on innate lymphoid cells (ILCs). The number of circulating retinoic acid receptor-related orphan receptor γt-positive ILCs, which include lymphoid tissue inducer (LTi) cells, was found to be elevated in untreated MS patients compared to healthy subjects. Daclizumab therapy not only decreased numbers of ILCs but also modified their phenotype away from LTi cells and toward a natural killer (NK) cell lineage. Mechanistic studies indicated that daclizumab inhibited differentiation of LTi cells from CD34+ hematopoietic progenitor cells or c-kit+ ILCs indirectly, steering their differentiation toward immunoregulatory CD56bright NK cells through enhanced intermediate-affinity IL-2 signaling. Because adult LTi cells may retain lymphoid tissue-inducing capacity or stimulate adaptive immune responses, we indirectly measured intrathecal inflammation in daclizumab-treated MS patients by quantifying the cerebrospinal fluid chemokine (C-X-C motif) ligand 13 and immunoglobulin G index. Both of these inflammatory biomarkers were inhibited by daclizumab treatment. Our study indicates that ILCs are involved in the regulation of adaptive immune responses, and their role in human autoimmunity should be investigated further, including their potential as therapeutic targets.

Jeong G.S.,Korea University | Baek D.-H.,Korea University | Jung H.C.,Korea University | Song J.H.,Korea University | And 4 more authors.
Nature Communications | Year: 2012

A variety of flexible and stretchable electronics have been reported for use in flexible electronic devices or biomedical applications. The practical and wider application of such flexible electronics has been limited because commercial electronic components are difficult to be directly integrated into flexible stretchable electronics and electroplating is still challenging. Here, we propose a novel method for fabricating flexible and stretchable electronic devices using a porous elastomeric substrate. Pressurized steam was applied to an uncured polydimethylsiloxane layer for the simple and cost-effective production of porous structure. An electroplated nickel anchor had a key role in bonding commercial electronic components on elastomers by soldering techniques, and metals could be stably patterned and electroplated for practical uses. The proposed technology was applied to develop a plaster electrocardiogram dry electrode and multi-channel microelectrodes that could be used as a long-term wearable biosignal monitor and for brain signal monitoring, respectively. © 2012 Macmillan Publishers Limited. All rights reserved.

Moon I.K.,Pusan National University | Cha B.C.,Changwon National University | Lee C.U.,Korea University
International Journal of Production Economics | Year: 2011

We have developed joint replenishment and consolidated freight delivery policies for a third party warehouse that handles multiple items, which have deterministic demand rates in a supply chain. Two policies are proposed and mathematical models are developed to obtain the optimal parameters for the proposed policies. Four efficient algorithms are presented to solve the mathematical models for the two policies. The performances of the two policies with the parameters obtained from the proposed algorithms are then compared with the common cycle approach for 1600 randomly generated problems. The results show the robust performance of the proposed algorithm for both policies. © 2010 Elsevier B.V. All rights reserved.

Shon Z.-H.,Dong - Eui University | Kim K.-H.,Sejong University | Song S.-K.,Pusan National University
Atmospheric Environment | Year: 2011

Long-term trend in emission ratio of NO2 to NOx was analyzed in relation to traffic activities using ambient monitoring data (such as NO, NO2, NOx, and O3) collected from 7 urban roadside (U-RS) and 7 urban background (U-BG) locations in Seoul, Korea over a 14-year period (1996-2009). In general, the temporal trend of NO2 concentrations is less distinctive than that of NOx, whether being downward or upward. However, if their differences are checked statistically, only a few cases were significant. The mean emission ratio of NO2 to NOx values varied slightly across the 7 U-RS sites during the study period, ranging from 0.11 to 0.19. In general, there was no significant annual trend in the relative fraction of NO2 in NOx emission (f(NO2)) at U-RS, with an exceptional downward trend at one site (slope of -0.008y-1). On the other hand, diurnal variations of f(NO2) were likely affected by driving conditions and fuel type of vehicles. The overall results of this study suggest that NOx emission control strategies such as diesel particulate filter (DPF) or diesel oxidation catalyst (DOC) should have direct influences on f(NO2) values at U-RS sites. © 2011 Elsevier Ltd.

News Article | November 18, 2016
Site: en.prnasia.com

SEOUL, South Korea, Nov 18, 2016 /PRNewswire/ -- Sae-A Trading Co., Ltd (Sae-A), a leading global apparel manufacturer and exporter, led its fourth medical mission since 2012, to Northern Haiti. The mission provides free medical care to local area residents in the neighboring communities around the area each time averaging more than 3,000 people over a (five day) week. 25 medical professionals from the USA (George Washington University School of Nursing), South Korea (Pusan National University Yangsan Hospital) and Haiti (The Vision Plus Eye Clinic in Cap Haitian) spent the week treating local residents at the Sae-A supported, S&H Primary School, while the students were on fall break. The classrooms are converted into temporary medical treatment rooms. Sae-A provided transportation to area residents who needed care, but were unable to reach the school. The team of 25 medical professionals bring a wide variety of expertise across multiple disciplines including pediatrics, obstetrics, otolaryngology, urology, dermatology, pain management, ophthalmology and family medicine. Special attention is paid to mothers-to-be, infants and children who are not only screened for diseases, but also provided wellness examinations and health information on issues ranging from disease prevention to nutrition. The mission's goal is to both to provide best-in-class care to clinic patients, as well as help educate the community about best practices in hygiene to help prevent future diseases. A main focus of the educational programming, done in cooperation with local community hospitals, was the prevention and treatment of cholera and other infectious diseases that are present in the region. For the third time, ophthalmology has been one of the services provided. Vision Plus, based in Cap Haitian, conducted vision examinations on nearly 600 residents providing those with vision problems prescription corrective glasses as well as to provide treatment and screening for disorders that include dry eye, allergic conjunctivitis, eye trauma, infections, glaucoma and cataracts. "Sae-A is always working to be a beneficial member of the community," said Sae-A's Chairman Woong-Ki Kim. "Our goal through the medical mission is to provide primary health care services, screening and health education for as many adults and children in the communities around the Caracol Industrial Park. We are particularly happy to have partners from Korea, the United States and Haiti join us on our fourth medical mission since 2012. We are grateful to our neighbors for their gracious welcome and remain committed to their well-being. We are particularly proud that any additional supplies from the medical mission will be provided to the Government of Haiti to help treat victims of Hurricane Matthew." Sae-A, which marked its 30th year of operations earlier this year, regularly invests in various CSR programs in support of the communities in the areas where it operates. From supporting relief efforts to providing medical treatment to educating more than 400 local students, Sae-A takes its role in the community extremely seriously. Sae-A invested in and fully funds the operation of the S&H Primary School in a neighborhood near the Industrial Park. The S&H Primary School which provides a best-in-class (free) education to nearly 400 students. The school is led by a team of experienced local and international educators and includes a multi-lingual curriculum and leverages technology to create the best learning experience possible. Sae-A collaborated with the Government of Haiti, the Korea International Cooperation Agency, and local stakeholders to ensure national requirements would be met. The S&H Secondary School opened this past September which allows the graduates from the Primary School to continue receiving the same quality education without interruption. Each year the school will grow with its senior-most class through the completion of 12th grade essentially doubling enrollment. Moreover, S&H School's impact on the community goes beyond the class day. It will serve the Caracol-EKAM area by acting as a community center and hosting social events, and provide opportunities for area residents to participate in English and other adult education classes and activities that promote the concept that education begins at home and the community is an extension of the classroom. For more information on Sae-A's social responsibility programs and initiatives in Haiti, please visit: www.sae-a.com. About Sae-A Trading Co., Ltd Established in 1986, Sae-A Trading Co., Ltd is one of the world's largest apparel manufacturing companies employing over 60,000 associates throughout Southeast Asia, Central America and the Caribbean with exports of apparel and textiles exceeding $1.6 billion dollars. To view the original version on PR Newswire, visit:http://www.prnewswire.com/news-releases/sae-a-and-partners-send-fourth-medical-mission-to-haiti-300363959.html

Seo K.-I.,Yale University | Lee J.-H.,Yale University | Lee J.-H.,Pusan National University | Nezames C.D.,Yale University | And 4 more authors.
Plant Cell | Year: 2014

Members of the DDB1-CUL4-associated factors (DCAFs) family directly bind to DAMAGED DNA BINDING PROTEIN1 (DDB1) and function as the substrate receptors in CULLIN4-based E3 (CUL4) ubiquitin ligases, which regulate the selective ubiquitination of proteins. Here, we describe a DCAF protein, ABD1 (for ABA-hypersensitive DCAF1), that negatively regulates abscisic acid (ABA) signaling in Arabidopsis thaliana. ABD1 interacts with DDB1 in vitro and in vivo, indicating that it likely functions as a CUL4 E3 ligase substrate receptor. ABD1 expression is induced by ABA, and mutations in ABD1 result in ABA-and NaCl-hypersensitive phenotypes. Loss of ABD1 leads to hyperinduction of ABA-responsive genes and higher accumulation of the ABA-responsive transcription factor ABA INSENSITIVE5 (ABI5), hypersensitivity to ABA during seed germination and seedling growth, enhanced stomatal closure, reduced water loss, and, ultimately, increased drought tolerance. ABD1 directly interacts with ABI5 in yeast two-hybrid assays and associates with ABI5 in vivo by coimmunoprecipitation, and the interaction was found in the nucleus by bimolecular fluorescence complementation. Furthermore, loss of ABD1 results in a retardation of ABI5 degradation by the 26S proteasome. Taken together, these data suggest that the DCAF-CUL4 E3 ubiquitin ligase assembled with ABD1 is a negative regulator of ABA responses by directly binding to and affecting the stability of ABI5 in the nucleus. © 2014 American Society of Plant Biologists. All rights reserved.

Seo K.-H.,Pusan National University | Wang W.,National Oceanic and Atmospheric Administration
Journal of Climate | Year: 2010

This study investigates the capability for simulating the Madden-Julian oscillation (MJO) in a series of atmosphere-ocean coupled and uncoupled simulations using NCEP operational general circulation models. The effect of air-sea coupling on the MJO is examined by comparing long-term simulations from the coupled Climate Forecast System (CFS T62) and the atmospheric Global Forecast System (GFS T62) models. Another coupled simulation with a higher horizontal resolution model (CFS T126) is performed to investigate the impact of model horizontal resolution. Furthermore, to examine the impact on a deep convection scheme, an additional coupled T126 run (CFS T126RAS) is conducted with the relaxed Arakawa-Schubert (RAS) scheme. The most important factors for the proper simulation of the MJO are investigated from these runs. The empirical orthogonal function, lagged regression, and spectral analyses indicated that the interactive air-sea coupling greatly improved the coherence between convection, circulation, and other surface fields on the intraseasonal time scale. A higher horizontal resolution run (CFS T126) did not show significant improvements in the intensity and structure. However, GFS T62, CFS T62, and CFS T126 all yielded the 30-60-day variances that were not statistically distinguishable from the background red noise spectrum. Their eastward propagation was stalled over the Maritime Continent and far western Pacific. In contrast to the model simulations using the simplified Arakawa-Schubert (SAS) cumulus scheme, CFS T126RAS produced statistically significant spectral peaks in the MJO frequency band, and greatly improved the strength of the MJO convection and circulation. Most importantly, the ability of MJO convection signal to penetrate into the Maritime Continent and western Pacific was demonstrated. In this simulation, an early-stage shallow heating and moistening preconditioned the atmosphere for subsequent intense MJO convection and a top-heavy vertical heating profile was formed by stratiform heating in the upper and middle troposphere, working to increase temperature anomalies and hence eddy available potential energy that sustains the MJO. The stratiform heating arose from convective detrainment of moisture to the environment and stratiform anvil clouds. Therefore, the following factors were analyzed to be most important for the proper simulation of the MJO rather than the correct simulations of basic-state precipitation, sea surface temperature, intertropical convergence zone, vertical zonal wind shear, and lower-level zonal winds: 1) an elevated vertical heating structure (by stratiform heating), 2) a moisture-stratiform instability process (a positive feedback process between moisture and convective-stratiform clouds), and 3) the low-level moisture convergence to the east of MJO convection (through the appropriate moisture and convective-stratiform cloud processes-circulation interactions). The improved MJO simulation did improve the global circulation response to the tropical heating and may extend the predictability of weather and climate over Asia and North America. © 2010 American Meteorological Society.

Lee J.,Pusan National University | Lee J.,Massachusetts Institute of Technology | Littleton J.T.,Massachusetts Institute of Technology
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Synaptotagmin 1 (Syt1) is a synaptic vesicle integral membrane protein that regulates neurotransmitter release by activating fast synchronous fusion and suppressing slower asynchronous release. The cytoplasmic C2 domains of Syt1 interact with SNAREs and plasma membrane phospholipids in a Ca2+-dependent manner and can substitute for full-length Syt1 in in vitro membrane fusion assays. To determine whether synaptic vesicle tethering of Syt1 is required for normal fusion in vivo, we performed a structure-function study with tethering mutants at the Drosophila larval neuromuscular junction. Transgenic animals expressing only the cytoplasmic C2 domains or full-length Syt1 tethered to the plasma membrane failed to restore synchronous synaptic vesicle fusion, and also failed to clamp spontaneous vesicle release. In addition, transgenic animalswith shorter, but not those with longer, linker regions separating the C2 domains from the transmembrane segment abolished Syt1's ability to activate synchronous vesicle fusion. Similar defects were observed when C2 domain alignment was altered to C2B-C2A from the normal C2A-C2B orientation, leaving the tether itself intact. Although cytoplasmic and plasma membrane-tethered Syt1 variants could not restore synchronous release in syt1 null mutants, they were very effective in promoting fusion through the slower asynchronous pathway. As such, the subcellular localization of Syt1 within synaptic terminals is important for the temporal dynamics that underlie synchronous and asynchronous neurotransmitter release. © 2015, National Academy of Sciences. All rights reserved.

Cho D.W.,Yeungnam University | Mariano P.S.,University of New Mexico | Yoon U.C.,Pusan National University
Beilstein Journal of Organic Chemistry | Year: 2014

In this review, we describe direct and indirect photochemical approaches that have been developed for the preparation of phthalimide- and naphthalimide-based, lariat-type crown ethers. The direct route utilizes a strategy in which nitrogen-linked side chains containing polyethoxy-tethered phthalimides and naphthalimides, possessing terminal a-trialkylsilyl groups, are synthesized utilizing concise routes and UV-irradiation to form macrocyclic ring systems. In contrast, the indirect route developed for the synthesis of lariat-type crown ethers employs sequences in which SET-promoted macrocyclization reactions of a-trialkylsilyl-terminated, polyethoxy-tethered phthalimides and naphthalimides are followed by a side chain introduction through substitution reactions at the amidol centers in the macrocyclic ethers. The combined observations made in these investigations demonstrate the unique features of SET-promoted photocyclization reactions that make them well-suited for the use in the synthesis of functionalized crown ethers. In addition, while some limitations exist for the general use of SET-photochemical reactions in large-scale organic synthesis, important characteristics of the photoinduced macrocyclization reactions make them applicable to unique situations in which high temporal and spatial control is required. © 2014 Cho et al; licensee Beilstein-Institut.

Cho D.W.,University of New Mexico | Yoon U.C.,Pusan National University | Mariano P.S.,University of New Mexico
Accounts of Chemical Research | Year: 2011

Organic photochemists began to recognize in the 1970sthat a new mechanistic pathway involving excited-state single-electron transfer (SET) could be used to drive unique photochemical reactions. Arnold's seminal studies demonstrated that SET photochemical reactions proceed by way of ion radical intermediates, the properties of which govern the nature of the ensuing reaction pathways. Thus, in contrast to classical photochemical reactions, SET-promoted excited-state processes are controlled by the nature and rates of secondary reactions of intermediate ion radicals. In this Account, we discuss our work in harnessing SET pathways for photochemical synthesis, focusing on the successful production of macrocyclic polyethers, polythioethers, and polyamides.One major thrust of our studies in SET photochemistry has been to develop new, efficient reactions that can be used for the preparation of important natural and non-natural substances. Our efforts with α-silyl donor-tethered phthalimides and naphthalimides have led to the discovery of efficient photochemical processes in which excited-state SET is followed by regioselective formation of carbon-centered radicals. The radical formation takes place through nucleophile-assisted desilylation of intermediate α-silyl- substituted ether-, thioether-, amine-, and amide-centered cation radicals.Early laser flash photolysis studies demonstrated that the rates of methanol- and water-promoted bimolecular desilylations of cation radicals (derived from α-silyl electron donors) exceeded the rates of other cation radical α-fragmentation processes, such as α-deprotonation. In addition, mechanistic analyses of a variety of SET-promoted photocyclization reactions of α-silyl polydonor-linked phthalimides and naphthalimides showed that the chemical and quantum efficiencies of the processes are highly dependent on the lengths and types of the chains connecting the imide acceptor and α-silyl electron donor centers. We also observed that reaction efficiencies are controlled by the rates of desilylation at the α-silyl donor cation radical moieties in intermediate zwitterionic biradicals that are formed by either direct excited-state intramolecular SET or by SET between the donor sites in the intervening chains.It is important to note that knowledge about how these factors govern product yields, regiochemical selectivities, and quantum efficiencies was crucial for the design of synthetically useful photochemical reactions of linked polydonor-acceptor substrates. The fruits of these insights are exemplified by synthetic applications in the concise preparation of cyclic peptide mimics, crown ethers and their lariat- and bis-analogs, and substances that serve as fluorescence sensors for important heavy metal cations. © 2010 American Chemical Society.

Park C.S.,Ericsson AB | Park F.S.,Pusan National University
IEEE Transactions on Wireless Communications | Year: 2011

The capability of error correction codes is largely dependent on the calculation of soft decision values. In this letter, linear-dispersion (LD) code is applied to single-carrier frequency-division multiple access (SC-FDMA) and the closed-form expression of soft decision values is derived. It is shown that the calculation of soft decision values generally depends on both time and space within an SC-FDMA symbol, as opposed to single-antenna transmission. In addition, a sufficient condition to guarantee the independence from time and space is presented. © 2011 IEEE.

Jang T.S.,Pusan National University | Sung H.G.,Maritime and Ocean Engineering Research Institute
International Journal of Non-Linear Mechanics | Year: 2012

We propose a new non-linear method for the static analysis of an infinite non-uniform beam resting on a non-linear elastic foundation under localized external loads. To this end, an integral operator equation is newly formulated, which is equivalent to the original differential equation of non-uniform beam. By using the integral operator equation, we propose a new functional iterative method for static beam analysis as a general approach to a variable beam cross-section. The method proposed is fairly simple as well as straightforward to apply. An illustrative example is presented to examine the validity of the proposed method. It shows that just a few iterations are required for an accurate solution. © 2012 Elsevier Ltd. All rights reserved.

Cui J.F.,Xiamen University of Technology | Chae H.S.,Pusan National University
Information and Software Technology | Year: 2011

Context: Component identification, the process of evolving legacy system into finely organized component-based software systems, is a critical part of software reengineering. Currently, many component identification approaches have been developed based on agglomerative hierarchical clustering algorithms. However, there is a lack of thorough investigation on which algorithm is appropriate for component identification. Objective: This paper focuses on analyzing agglomerative hierarchical clustering algorithms in software reengineering, and then identifying their respective strengths and weaknesses in order to apply them effectively for future practical applications. Method: A series of experiments were conducted for 18 clustering strategies combined according to various similarity measures, weighting schemes and linkage methods. Eleven subject systems with different application domains and source code sizes were used in the experiments. The component identification results are evaluated by the proposed size, coupling and cohesion criteria. Results: The experimental results suggested that the employed similarity measures, weighting schemes and linkage methods can have various effects on component identification results with respect to the proposed size, coupling and cohesion criteria, so the hierarchical clustering algorithms produced quite different clustering results. Conclusions: According to the experimental results, it can be concluded that it is difficult to produce perfectly satisfactory results for a given clustering algorithm. Nevertheless, these algorithms demonstrated varied capabilities to identify components with respect to the proposed size, coupling and cohesion criteria. © 2011 Elsevier B.V. All rights reserved.

Young Yun W.,Pusan National University | Mi Lee Y.,Pusan National University | Seok Choi Y.,Sunchon National University
International Journal of Production Economics | Year: 2011

In this paper, we deal with an inventory control problem of empty containers in an inland transportation system. In inland container transportation, freights (containers) are transported between terminal and the customer's location by trucks, trains and barges. Empty containers are an important logistic resource and shipping companies try to operate and manage empty containers efficiently. Because of the trade imbalance between hub ports, empty containers should be periodically repositioned from surplus areas to shortage areas. However, it is not easy to exactly forecast the demand of empty containers, and we therefore need to build an efficient way to reposition the empty containers. In this paper, we consider a shortage area and propose an efficient inventory policy to control empty containers. We assume that demands per unit time are independent and identically distributed random variables. To satisfy the demand of empty containers, we reposition empty containers from other hubs based on the (s, S) inventory policy, and also consider the lease of empty containers with zero lead time. For the leased containers, we should return the number of empty containers leased to the leaser after the specified period. For a given policy, simulation is used to estimate the expected cost rate and we use the optimization tool, OptQuest® in Arena to obtain the near optimal (s, S) policy in numerical examples. © 2010 Elsevier B.V. All rights reserved.

Wang J.,EMC | Wang W.,National Oceanic and Atmospheric Administration | Fu X.,University of Hawaii at Manoa | Seo K.-H.,Pusan National University
Climate Dynamics | Year: 2012

While large-scale circulation fields from atmospheric reanalyses have been widely used to study the tropical intraseasonal variability, rainfall variations from the reanalyses are less focused. Because of the sparseness of in situ observations available in the tropics and strong coupling between convection and large-scale circulation, the accuracy of tropical rainfall from the reanalyses not only measures the quality of reanalysis rainfall but is also to some extent indicative of the accuracy of the circulations fields. This study analyzes tropical intraseasonal rainfall variability in the recently completed NCEP Climate Forecast System Reanalysis (CFSR) and its comparison with the widely used NCEP/NCAR reanalysis (R1) and NCEP/DOE reanalysis (R2). The R1 produces too weak rainfall variability while the R2 generates too strong westward propagation. Compared with the R1 and R2, the CFSR produces greatly improved tropical intraseasonal rainfall variability with the dominance of eastward propagation and more realistic amplitude. An analysis of the relationship between rainfall and large-scale fields using composites based on Madden-Julian Oscillation (MJO) events shows that, in all three NCEP reanalyses, the moisture convergence leading the rainfall maximum is near the surface in the western Pacific but is above 925 hPa in the eastern Indian Ocean. However, the CFSR produces the strongest large-scale convergence and the rainfall from CFSR lags the column integrated precipitable water by 1 or 2 days while R1 and R2 rainfall tends to lead the respective precipitable water. Diabatic heating related to the MJO variability in the CFSR is analyzed and compared with that derived from large-scale fields. It is found that the amplitude of CFSR-produced total heating anomalies is smaller than that of the derived. Rainfall variability from the other two recently produced reanalyses, the ECMWF Re-Analysis Interim (ERAI), and the Modern Era Retrospective-analysis for Research and Applications (MERRA), is also analyzed. It is shown that both the ERAI and MERRA generate stronger rainfall spectra than the R1 and more realistic dominance of eastward propagating variance than R2. The intraseasonal variability in the MERRA is stronger than that in the ERAI but weaker than that in the CFSR and CMORPH. © 2011 Springer-Verlag.

Pusan National University, Korea Research Institute of Chemical Technology and Gachon University | Date: 2013-10-11

The present invention relates to a method for preparing a protein cage which comprises: a 1^(st )step of preparing an amphiphilic polymer comprising a 1^(st )hydrophobic polymer and a 1^(st )hydrophilic functional group; a 2^(nd )step of preparing a hydrophilic protein comprising a 2^(nd )functional group binding to the 1^(st )functional group; a 3^(rd )step of forming an amphiphilic polymer-protein hybrid by the binding of the 1^(st )functional group and the 2^(nd )functional group, and forming core-shell structured particles comprising a protein shell and an amphiphilic polymer core by the self-assembly of the amphiphilic polymer in a hydrophilic solvent; and a fourth step of removing some or all of the hydrophobic polymer of the core part from the core-shell structured particles.

Cho H.-S.,Pusan National University | Ochsner E.,University of Wisconsin - Milwaukee | O'Shaughnessy R.,University of Wisconsin - Milwaukee | Kim C.,West Virginia University | Lee C.-H.,Pusan National University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Inspiralling black hole-neutron star binaries emit a complicated gravitational wave signature, produced by multiple harmonics sourced by their strong local gravitational field and further modulated by the orbital plane's precession. Some features of this complex signal are easily accessible to ground-based interferometers (e.g., the rate of change of frequency), others less so (e.g., the polarization content), and others still are unavailable (e.g., features of the signal out of band). For this reason, an ambiguity function (a diagnostic of dissimilarity) between two such signals varies on many parameter scales and ranges. In this paper, we present a method for computing an approximate, effective Fisher matrix from variations in the ambiguity function on physically pertinent scales which depend on the relevant signal-to-noise ratio. As a concrete example, we explore how higher harmonics improve parameter measurement accuracy. As previous studies suggest, for our fiducial black hole-neutron star binaries and for plausible signal amplitudes, we see that higher harmonics at best marginally improve our ability to measure parameters. For nonprecessing binaries, these Fisher matrices separate into intrinsic (mass, spin) and extrinsic (geometrical) parameters; higher harmonics principally improve our knowledge about the line of sight. For the precessing binaries, the extra information provided by higher harmonics is distributed across several parameters. We provide concrete estimates for measurement accuracy, using coordinates adapted to the precession cone in the detector's sensitive band. © 2013 American Physical Society.

Kim T.G.,Pusan National University | Knudsen G.R.,University of Idaho
Applied Soil Ecology | Year: 2016

DNA quantification has become a conventional method for quantifying filamentous fungi in environments. In this study, quantitative PCR was evaluated as a quantification tool by comparisons with plate count (unit, recoverable population) and microscopy with image analysis (hyphal biomass). The genetic transformant Trichoderma harzianumThzID1-M3 was used as a model organism. A soil microcosm experiment with different numbers of ThzID1-M3 alginate pellets showed that DNA was significantly correlated with biomass (P< 0.05), but not with CFU. Temporal change of ThzID1-M3 was monitored at -50 and -500 kPa for a 21-day period. Biomass peaked within the first 5 days, followed by a rapid reduction, while CFU peaked at between days 14 and 21, indicating that CFU mainly originated from dormant propagules. DNA increased along with biomass, and then increased again in accordance with the CFU increase. These results demonstrated that DNA estimates do not strictly correspond to either the population of recoverable propagules or hyphal biomass. However, DNA estimates can reflect relative changes of active and/or dormant propagules although they are unable to distinguish between them. © 2015 Elsevier B.V..

Shon C.-S.,Texas A&M University | Kim Y.-S.,Pusan National University
Construction and Building Materials | Year: 2013

Abstract This paper presents a comprehensive laboratory evaluation for West Texas natural zeolite as an alternative of ASTM Class F fly ash. The suggested laboratory testing program focused on three areas of interest: (i) characterization of physical, chemical, mineralogical, and morphological aspects of zeolite, (ii) determination of fresh and hardened properties on zeolite mortar specimens including setting behavior, heat of hydration, workability, and strength, (iii) durability evaluation such as alkali-silica reaction (ASR) and sulfate attack. Test results indicated that the natural zeolites used in this study satisfied with chemical requirements of ASTM C 618 Standard Specification. The mixture also met the minimum compressive strength activity indices at 7 days and 28 days for Type N and Type F (ASTM C 618), but showed slightly lower strength at 91-day when compared with fly ash mixtures. Moreover, zeolite mixture generated less heat of hydration and reduction of drying shrinkage when compared with the control and fly ash mixtures. The mixture showed considerably higher resistance to alkali-silica reaction as well as sulfate attack. However, zeolite mixture required a high water demand and showed lower workability than mixtures with fly ash because of high fineness, honey-comb structure, and angular shape of zeolite. © 2013 Elsevier Ltd. All rights reserved.

Lee J.-A.,Kyungsung University | Kim J.-W.,Pusan National University | Kim D.-Y.,Kyungsung University | Kim D.-Y.,Pusan National University
Menopause | Year: 2012

Objective: Regular and continuous yoga exercise is one of the most important nonpharmacological methods of improving serum lipid concentrations, adipose tissue, and metabolic syndrome factors. The purpose of this study was to analyze the effects of yoga exercise on serum adiponectin and metabolic syndrome factors in obese postmenopausal Korean women. Methods: Sixteen healthy postmenopausal women aged 54.50 ± 2.75 years with more than 36% body fat were randomly assigned to either a yoga exercise group (n = 8) or to a "no exercise" control group (n = 8). The variables of body composition, visceral fat, serum adiponectin, and metabolic syndrome factors were measured in all the participants before and after the 16-week study. Results: Body weight, percentage of body fat, lean body mass, body mass index, waist circumference, and visceral fat area had significantly decreased. High-density lipoprotein cholesterol and adiponectin had significantly increased, but total cholesterol, triglyceride, low-density lipoprotein cholesterol, blood pressure, insulin, glucose, and homoeostasis model assessment-insulin resistance had significantly decreased. Serum adiponectin concentrations were significantly correlated with waist circumference, high-density lipoprotein cholesterol, diastolic blood pressure, and homoeostasis model assessment-insulin resistance in the postyoga exercise group. Conclusions: Our findings indicate that yoga exercise improves adiponectin level, serum lipids, and metabolic syndrome risk factors in obese postmenopausal women. Consequently, yoga exercise will be effective in preventing cardiovascular disease caused by obesity in obese postmenopausal Korean women. © 2012 The North American Menopause Society.

Kim M.-S.,Pusan National University | Baek I.-H.,Kyungsung University
International journal of nanomedicine | Year: 2014

The aim of this study was to fabricate valsartan composite nanoparticles by using the supercritical antisolvent (SAS) process, and to evaluate the correlation between in vitro dissolution and in vivo pharmacokinetic parameters for the poorly water-soluble drug valsartan. Spherical composite nanoparticles with a mean size smaller than 400 nm, which contained valsartan, were successfully fabricated by using the SAS process. X-ray diffraction and thermal analyses indicated that valsartan was present in an amorphous form within the composite nanoparticles. The in vitro dissolution and oral bioavailability of valsartan were dramatically enhanced by the composite nanoparticles. Valsartan-hydroxypropyl methylcellulose-poloxamer 407 nanoparticles exhibited faster drug release (up to 90% within 10 minutes under all dissolution conditions) and higher oral bioavailability than the raw material, with an approximately 7.2-fold higher maximum plasma concentration. In addition, there was a positive linear correlation between the pharmacokinetic parameters and the in vitro dissolution efficiency. Therefore, the preparation of composite nanoparticles with valsartan-hydroxypropyl methylcellulose and poloxamer 407 by using the SAS process could be an effective formulation strategy for the development of a new dosage form of valsartan with high oral bioavailability.

Shin J.-A.,Chonbuk National University | Jung J.-Y.,Kongju National University | Ryu M.H.,Pusan National University | Safe S.,Texas A&M University | Cho S.-D.,Chonbuk National University
Molecular Pharmacology | Year: 2013

In several human malignancies, overexpression of myeloid cell leukemia-1 (Mcl-1) confers resistance to induction of apoptosis; however, Mcl-1-mediated inhibition of apoptosis in oral squamous cell carcinoma (OSCC) is not fully understood and has been investigated in this study. The Mcl-1 promoter activators (TPA) and epidermal growth factor (EGF) enhanced neoplastic transformation of JB6 cells and this response was accompanied by enhanced expression of Mcl-1, and knockdown of Mcl-1 by RNA interference (RNAi) decreased JB6 cell transformation. In the same cell line, we also demonstrated that mithramycin A (Mith) decreased TPA-induced JB6 cell transformation and Mcl-1 expression. Mcl-1 was overexpressed in human oral tumors compared with normal oral mucosa and also in several OSCC cell lines including HN22 and HSC-4 cells. Treatment of these cells with Mith also decreased Mcl-1 expression and neoplastic cell transformation, and this was accompanied by induction of several markers of apoptosis. Knockdown of Mcl-1 by RNAi also induced apoptotic cell death. The downregulation of Mcl-1 by Mith and RNAi increased pro-apoptotic protein Bax, resulting in the Bax translocation into mitochondria and its oligomerization. Mith also suppressed tumor growth in vivo and induced apoptosis in tumor by also regulating expression of Mcl-1 and Bax proteins. These indicate a critical role for Mcl-1 in the growth and survival of OSCC and demonstrate that Mith may be a potential anticancer drug candidate for clinical treatment of OSCC. Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics.

Nakayama H.,RIKEN | Kurokawa K.,Pusan National University | Lee B.L.,Pusan National University
FEBS Journal | Year: 2012

Bacterial lipoproteins are characterized by the presence of a conserved N-terminal lipid-modified cysteine residue that allows the hydrophilic protein to anchor onto bacterial cell membranes. These proteins play important roles in a wide variety of bacterial physiological processes, including virulence, and induce innate immune reactions by functioning as ligands of the mammalian Toll-like receptor 2. We review recent advances in our understanding of bacterial lipoprotein structure, biosynthesis and structure-function relationships between bacterial lipoproteins and Toll-like receptor 2. Notably, 40 years after the first report of the triacyl structure of Braun's lipoprotein in Escherichia coli, recent intensive MS-based analyses have led to the discovery of three new lipidated structures of lipoproteins in monoderm bacteria: the lyso, N-acetyl and peptidyl forms. Moreover, the bacterial lipoprotein structure is considered to be constant in each bacterium; however, lipoprotein structures in Staphylococcus aureus vary between the diacyl and triacyl forms depending on the environmental conditions. Thus, the lipidation state of bacterial lipoproteins, particularly in monoderm bacteria, is more complex than previously assumed. Bacterial lipoproteins have covalently-linked fatty acids at the N-terminus, enabling them to anchor on cell membranes and to stimulate host innate immunity. Here, we review recent advances in our understandings of lipoproteins, which include mass spectrometry-driven determination of novel lipid-modified structures and environment-mediated alteration in lipid modifications. These discoveries are now changing the conventional view of bacterial lipoproteins © 2012 The Authors Journal compilation © 2012 FEBS.

Seo K.-H.,Pusan National University | Son S.-W.,McGill University
Journal of the Atmospheric Sciences | Year: 2012

The detailed dynamical mechanisms of the upper-tropospheric circulation response to the Madden-Julian oscillation (MJO) convection are examined by integrating a primitive equation model. A series of initial-value calculations with the climatological boreal winter background flow forced by the MJO-like thermal forcing successfully capture the key aspects of the observed circulation response to the MJO convection. This suggests that a large fraction of MJO-related circulation anomalies are direct responses to tropical heating in both the tropics and extratropics and can be largely explained by linear dynamics. It is found that MJO-like dipole heatings not only intensify tropical upper-tropospheric anomalies but also weaken them at certain regions because of the interaction between equatorial Kelvin and Rossby waves. The Rossby wave train primarily excited by horizontal divergence of upper-level perturbation flow propagates northeastward and then heads back to the equator. In this way, Rossby wave activity once generated over the subtropical Indian Ocean tends to enhance the equatorial upper-tropospheric anomalies over the tropical Atlantic and West Africa that have already been created by the zonally propagating equatorial Rossby and Kelvin waves. A ray path tracing reveals that a successive downstream development of Rossby wave train mostly results fromthe large-scale waves with zonal waven umbers 2-3 in the Northern Hemisphere and 3-5 in the Southern Hemisphere. The sensitivity tests show that the overall results are quite robust. It is found, however, that the detailed circulation response to the MJO-like forcing is somewhat sensitive to the background flow. This suggests that MJO-related circulation anomalies may have nonnegligible long-term variability and change as background flow varies. © 2012 American Meteorological Society.

Reyes F.C.,University of Wisconsin - Madison | Chung T.,University of Wisconsin - Madison | Chung T.,Pusan National University | Holding D.,University of Nebraska - Lincoln | And 3 more authors.
Plant Cell | Year: 2011

Zeins, the prolamin storage proteins found in maize (Zea mays), accumulate in accretions called protein bodies inside the endoplasmic reticulum (ER) of starchy endosperm cells. We found that genes encoding zeins, a-globulin, and legumin-1 are transcribed not only in the starchy endosperm but also in aleurone cells. Unlike the starchy endosperm, aleurone cells accumulate these storage proteins inside protein storage vacuoles (PSVs) instead of the ER. Aleurone PSVs contain zeinrich protein inclusions, a matrix, and a large system of intravacuolar membranes. After being assembled in the ER, zeins are delivered to the aleurone PSVs in atypical prevacuolar compartments that seem to arise at least partially by autophagy and consist of multilayered membranes and engulfed cytoplasmic material. The zein-containing prevacuolar compartments are neither surrounded by a double membrane nor decorated by AUTOPHAGY RELATED8 protein, suggesting that they are not typical autophagosomes. The PSV matrix contains glycoproteins that are trafficked through a Golgi-multivesicular body (MVB) pathway. MVBs likely fuse with the multilayered, autophagic compartments before merging with the PSV. The presence of similar PSVs also containing prolamins and large systems of intravacuolar membranes in wheat (Triticum aestivum) and barley (Hordeum vulgare) starchy endosperm suggests that this trafficking mechanism may be common among cereals. © 2011 American Society of Plant Biologists.

Gao X.,Japan Institute for Molecular Science | Jang J.,Pusan National University | Nagase S.,Japan Institute for Molecular Science
Journal of Physical Chemistry C | Year: 2010

The density functional theory method (M05-2X/6-31G(d)) was used to investigate reaction mechanisms for deoxygenation of graphene oxides (GOs) with hydrazine or heat treatment. Three mechanisms were identified as reducing epoxide groups of GO with hydrazine as a reducing agent. No reaction path was found for the hydrazine-mediated reductions of the hydroxyl, carbonyl, and carboxyl groups of GO. We instead discovered the mechanisms for dehydroxylation, decarbonylation, and decarboxylation using heat treatment. The hydrazine de-epoxidation and thermal dehydroxylation of GO have opposite dependencies on the reaction temperature. In both reduction types, the oxygen functionalities attached to the interior of an aromatic domain in GO are removed more easily, both kinetically and thermodynamically, than those attached at the edges of an aromatic domain. The hydrazine-mediated reductions of epoxide groups at the edges are suspended by forming hydrazino alcohols. We provide atomic-level elucidation for the deoxygenation of GO, characterize the product structures, and suggest how to optimize the reaction conditions further. © 2010 American Chemical Society.

Park C.,Pusan National University | Schade G.W.,Texas A&M University
Journal of Environmental Quality | Year: 2016

Long-term urban carbon cycle studies remain rare despite the importance of carbon for energy, air quality, and climate change. To study spatial and temporal variations of energy and carbon fluxes in a subtropical urban environment, eddy covariance flux measurements were conducted north of downtown Houston, TX, using a tall radio-tower installation. The results of the first 2 yr of measurements show that both concentrations and fluxes of CO2 display typical seasonal and diurnal variations in urban areas. The seasonal variation of net CO2 flux is driven by steady anthropogenic emissions dominated by car traffic and human respiration, moderated by the local deciduous tree foliage. Weekday-weekend differences were observed in carbon fluxes, but not concentrations, while diurnal changes were dominated by rush-hour peaks from traffic and vegetation influences. Interestingly, CO and CO2 concentrations, but not CO2 flux, exhibited long-term declines, especially comparing pre- and post-Hurricane Ike periods. A directional analysis of CO2 fluxes revealed that the highest fluxes typically occurred from northwest directions, most likely due to emissions from small industrial sources. Car traffic as carbon source was revealed via correlations of CO with CO2 during the morning rush hours, and of CO2 flux with traffic counts during winter time. The influence of urban vegetation on net CO2 fluxes was identified via correlations with daytime photosynthetically active radiation due to photosynthesis, and with nighttime temperatures due to ecosystem respiration. The study site is a net source of CO2 throughout all seasons. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. 5585 Guilford Rd., Madison, WI 53711 USA.

Pusan National University and Unist Academy Industry Research Corporation | Date: 2014-02-03

The present invention relates to a novel polymeric material for a highly efficient organic thin-film solar cell with high hole mobility and power conversion efficiency. In the polymeric material, a compound containing an electron donating group represented by Formula 1 or 2 and a compound containing an electron accepting group represented by one of Formulae 3 to 8 are repeatedly introduced in an alternating manner.

Wang H.,Northeastern University China | Wang H.,Pusan National University | Moon I.,Pusan National University | Yang S.,Northeastern University China | And 2 more authors.
Information Sciences | Year: 2012

Recently, multimodal optimization problems (MMOPs) have gained a lot of attention from the evolutionary algorithm (EA) community since many real-world applications are MMOPs and may require EAs to present multiple optimal solutions. In this paper, a memetic algorithm that hybridizes particle swarm optimization (PSO) with a local search (LS) technique, called memetic PSO (MPSO), is proposed for locating multiple global and local optimal solutions in the fitness landscape of MMOPs. Within the framework of the proposed MPSO algorithm, a local PSO model, where the particles adaptively form different species based on their indices in the population to search for different sub-regions in the fitness landscape in parallel, is used for globally rough exploration, and an adaptive LS method, which employs two different LS operators in a cooperative way, is proposed for locally refining exploitation. In addition, a triggered re-initialization scheme, where a species is re-initialized once converged, is introduced into the MPSO algorithm in order to enhance its performance of solving MMOPs. Based on a set of benchmark functions, experiments are carried out to investigate the performance of the MPSO algorithm in comparison with some EAs taken from the literature. The experimental results show the efficiency of the MPSO algorithm for solving MMOPs. © 2012 Elsevier Inc. All rights reserved.

Yun W.J.,Pusan National University | Kim Y.W.,Pusan National University | Kang Y.,Pusan National University | Lee J.,Pusan National University | And 2 more authors.
Nucleic Acids Research | Year: 2014

TAL1 is a key hematopoietic transcription factor that binds to regulatory regions of a large cohort of erythroid genes as part of a complex with GATA-1, LMO2 and Ldb1 the complex mediates long-range interaction between the β-globin locus control region (LCR) and active globin genes, and although TAL1 is one of the two DNA-binding complex members, its role is unclear. To explore the role of TAL1 in transcription activation of the human γ-globin genes, we reduced the expression of TAL1 in erythroid K562 cells using lentiviral short hairpin RNA, compromising its association in the β-globin locus. In the TAL1 knockdown cells, the γ-globin transcription was reduced to 35% and chromatin looping of the Gγ-globin gene with the LCR was disrupted with decreased occupancy of the complex member Ldb1 and LMO2 in the locus. However, GATA-1 binding, DNase I hypersensitive site formation and several histone modifications were largely maintained across the β-globin locus. In addition, overexpression of TAL1 increased the γ-globin transcription and increased interaction frequency between the Gγ-globin gene and LCR these results indicate that TAL1 plays a critical role in chromatin loop formation between the γ-globin genes and LCR, which is a critical step for the transcription of the γ-globin genes. © 2014 The Author(s). Published by Oxford University Press.

Parambadath S.,Pusan National University | Rana V.K.,Pusan National University | Zhao D.,Fudan University | Ha C.-S.,Pusan National University
Microporous and Mesoporous Materials | Year: 2011

N,N′-diureylenepiperazine-bridged periodic mesoporous organosilicas (PDPMOs) have been successfully synthesized through co-condensation of bissilylated N,N′-diureylenepiperazine (BPDU) and tetraethyl orthosilicate (TEOS), using a triblock copolymer (Pluronic P123) as a structure-directing agent in acidic conditions with various BPDU to TEOS ratios. These PMOs were characterized by small angle X-ray scattering (SAXS), N2 adsorption-desorption measurements, Fourier-transform infrared (FT-IR), solid-state 29Si MAS and 13C CP-MAS NMR spectroscopy, transmission electron (TEM) and scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). It was found that the organic functionalities could be introduced at a maximum of 30 mol% in the wall structure of the diureylenepiperazine-bridged periodic mesoporous organosilica (PDPMO-30) with respect to the total silicon content. The PDPMO-30 was thermally stable up to 230 °C. The PDPMOs have an ordered mesostructure, a high surface area (ranging from 663 to 316 m2 g -1), a medium pore volume (1.26-0.66 cm3 g-1), and uniform pore sizes (7.7-5.4 nm). To test a potential application of the PDPMO, in vitro assays of captopril or 5-flurouracil adsorption and delivery were carried out at pH 7.4. Due to the presence of hydrophilic urea moieties within the wall structure, the materials were shown to be particularly suitable for adsorption and desorption of drugs and could be utilized for controlled drug delivery.© 2010 Elsevier Inc. All rights reserved.

Chun H.H.,Pusan National University | Kim Y.H.,Dong - A University
Korean Journal of Chemical Engineering | Year: 2013

A divided wall column (DWC) has widely been utilized as an energy-efficient distillation column. When it is applied to the offshore floating liquefied natural gas (FLNG) plant, its compactness can provide a favorable distillation system for the unconventional plant on top of its high energy efficiency. We investigated the design characteristic, cost evaluation and operation difficulty of the DWC at its utilization in the FLNG plant. The results from the HYSYS simulation of the DWC were compared with those of the conventional distillation system, and the following was found from the study. The DWC replacing the depropanizer and debutanizer of the conventional distillation system requires 12.5% less investment cost. While the saving of 25% in steam cost is expected from the DWC, the total utility cost including the refrigerant cost is reduced by 20.2% due to the lower cost reduction of refrigeration in the DWC. © 2013 Korean Institute of Chemical Engineers, Seoul, Korea.

Lee J.-H.,Pusan National University | Yun H.S.,Konkuk University | Kwon C.,Dankook University
Molecules and Cells | Year: 2012

As sessile, plants are continuously exposed to potential dangers including various abiotic stresses and pathogen attack. Although most studies focus on plant responses under an ideal condition to a specific stimulus, plants in nature must cope with a variety of stimuli at the same time. This indicates that it is critical for plants to fine-control distinct signaling pathways temporally and spatially for simultaneous and effective responses to various stresses. Global warming is currently a big issue threatening the future of humans. Reponses to high temperature affect many physiological processes in plants including growth and disease resistance, resulting in decrease of crop yield. Although plant heat stress and defense responses share important mediators such as calcium ions and heat shock proteins, it is thought that high temperature generally suppresses plant immunity. We therefore specifically discuss on interactions between plant heat and defense responses in this review hopefully for an integrated understanding of these responses in plants. © The Korean Society for Molecular and Cellular Biology. All rights reserved.

Yeo I.-A.,Dong - A University | Yoon S.-H.,Pusan National University | Yee J.-J.,Dong - A University
Applied Energy | Year: 2013

This study proposes a method to create an urban planning support model, applying the Environment and energy Geographical Information System Database (E-GIS DB) through the urban life cycle to reduce energy use for environmentally friendly urban planning. The results deduced from this study are organized as follows.The proposed E-GIS construction model is composed of (a) an urban GIS integration model, (b) an E-GIS DB model, and (c) a visualization model. The urban GIS integration model has the ability to integrate urban GIS constructs as well as to connect and visualize urban planning and the environment and energy DB in 3D space. The E-GIS DB model includes a function to visualize the 2D and 3D information, which is used in the environment and energy planning of a city.To validate the proposed E-GIS construction model, a Korean city undergoing the urban planning process is selected as a case study. An E-GIS DB section with an 8. km. ×. 12. km area for the research subject area was constructed in 2D and 3D GIS, and the urban space, climate elements, and energy distribution characteristics are compared. © 2012 Elsevier Ltd.

Yeo I.-A.,Dong - A University | Yoon S.-H.,Pusan National University | Yee J.-J.,Dong - A University
Applied Energy | Year: 2013

This study proposes a new urban energy demand forecasting system that includes the following improvements: (a) a facility planning information database (DB), (b) an energy and planning statistics DB, and (c) an enhancement of the accuracy of the energy calculation method. Each of these improved aspects is involved in energy demand forecasting for urban planning. The results from this study are as follows.(1).An Environment and energy Geographical Information System Database (E-GIS DB), which provides the mesh unit facility information, was utilized to allow for the forecasting and control of urban energy demands for each unit space.(2).An energy consumption unit figure was connected with an energy simulation to diversify the level of the urban energy consumption sector and the primary energy into hourly information. This figure allows for more accurate demand forecasting.(3).Urban facilities were categorized according to energy use characteristics and were modeled to allow for energy demand forecasts.(4).The energy demand was considered in an urban climate during summer with the characteristics of the heating methods that are suitable for domestic circumstances. Thus, a separate algorithm was suggested for a cooling period and a heating/intermission period to enhance the accuracy of the demand forecasts.(5).The performance of this energy demand forecasting system was validated, such that excessively high or low calculated values can be modified from the current method in a 'planned city' while the urban energy demand can be forecasted relatively correct and in detail with differences of a factor of 0.20-0.44 for the cooling period in the 'existing city'.(6).The proposed urban energy demand forecasting system was constructed as EnerISS Solver which is an automated module. This module drastically reduced time consuming for predicting energy demand and urban climate to respond for the urban energy planning subjects' needs immediately. © 2013 Elsevier Ltd.

Park S.S.,Pusan National University | Chu S.-W.,Pusan National University | Xue C.,Fudan University | Zhao D.,Fudan University | Ha C.-S.,Pusan National University
Journal of Materials Chemistry | Year: 2011

Highly nitrogen-enriched mesoporous carbon nitride materials with 2-dimensional (2-D) (2D-meso-CN) and 3-dimensional (3-D) mesostructures (3D-meso-CN) were synthesized using mesoporous silica as a hard template and cyanamide as a precursor via the incipient wetness process without using any solvent. The materials were characterized by small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) for the mesostructure analysis, N2 adsorption-desorption isotherms for surface area and pore size distribution, and X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR) spectroscopy for the composition analysis of frameworks. The mesoporous carbon nitride replicas have graphitic-like stacking of carbon nitride sheets in mesopore walls. The N/C ratio of the mesoporous carbon nitride replicas is 1.13 after the carbonization at 550 °C for 3 h. 2D-meso-CN and 3D-meso-CN have the BET surface area of 361 and 343 m2 g-1, large pore volume of 0.50 and 0.67 cm3 g-1, and pore diameter of 27.8 Å (for 2D-meso-CN), 24.5 and 80.3 Å (for 3D-meso-CN), respectively. It was found that the 3D-meso-CN has higher capacity of hydrogen uptake of 0.25 wt% than the pure mesoporous carbon FDU-15 (0.16 wt%) at 50 bar under room temperature (298 K). © 2011 The Royal Society of Chemistry.

Zhai Y.,Fudan University | Dou Y.,Northeastern University China | Liu X.,Northeastern University China | Park S.S.,Pusan National University | And 2 more authors.
Carbon | Year: 2011

Ordered mesoporous carbon/nanoparticle nickel composites have been synthesized via multi-component co-assembly strategy associated with a direct carbonization process from resol, tetraethyl orthosilicate, Ni(NO 3)2·6H2O and triblock copolymer F127 and subsequent silicates removal with NaOH solution. The incorporation of rigid silicates in the pore walls can reduce framework shrinkage significantly during the pyrolysis process, creating large mesopores. Moreover, plenty of complementary small pores caused by silica removal are observed in the carbon pore walls, which contribute to the large surface area. The mesoporous carbon/nanoparticle nickel composites with a low Ni content (1.7 wt%) possess ordered two-dimensional hexagonal structure, large mesopores (6.8 nm), high surface area (1580 m2 g-1) and large pore volume (1.42 cm3 g-1). Magnetic Ni nanocrystals with particle size of ∼16.0 nm are confined in the matrix of carbon frameworks. With increase of Ni content, the surface area and pore volume of the composites decrease. The particle size of metallic Ni nanocrystals increases up to 20.3 nm, when its content increases to 10 wt%. These carbon/nanoparticle nickel composites with high surface area, large pore size and superparamagnetic property show excellent adsorption properties for bulky dye fuchsin base and an easy separation procedure. © 2010 Elsevier Ltd. All rights reserved.

Dong-Soon I.M.,Pusan National University | Seung-Yeol N.A.H.,Konkuk University
Acta Pharmacologica Sinica | Year: 2013

Ginseng, the root of Panax ginseng, has been used in traditional Chinese medicine as a tonic herb that provides many beneficial effects. Pharmacologic studies in the last decades have shown that ginsenosides (ginseng saponins) are primarily responsible for the actions of ginseng. However, the effects of ginseng are not fully explained by ginsenosides. Recently, another class of active ingredients called gintonin was identified. Gintonin is a complex of glycosylated ginseng proteins containing lysophosphatidic acids (LPAs) that are the intracellular lipid mitogenic mediator. Gintonin specifically and potently activates the G protein-coupled receptors (GPCRs) for LPA. Thus, the actions of ginseng are now also linked to LPA and its GPCRs. This linkage opens new dimensions for ginseng pharmacology and LPA therapeutics. In the present review, we evaluate the pharmacology of ginseng with the traditional viewpoint of Yin and Yang components. Furthermore, we will compare ginsenoside and gintonin based on the modern view of molecular pharmacology in terms of ion channels and GPCRs. © 2013 CPS and SIMM.

Hein G.,University of Zürich | Morishima Y.,University of Zürich | Morishima Y.,University of Bern | Morishima Y.,Japan Science and Technology Agency | And 3 more authors.
Science | Year: 2016

Goal-directed human behaviors are driven by motives. Motives are, however, purely mental constructs that are not directly observable. Here, we show that the brain's functional network architecture captures information that predicts different motives behind the same altruistic act with high accuracy. In contrast, mere activity in these regions contains no information about motives. Empathy-based altruism is primarily characterized by a positive connectivity from the anterior cingulate cortex (ACC) to the anterior insula (AI), whereas reciprocity-based altruism additionally invokes strong positive connectivity from the AI to the ACC and even stronger positive connectivity from the AI to the ventral striatum. Moreover, predominantly selfish individuals show distinct functional architectures compared to altruists, and they only increase altruistic behavior in response to empathy inductions, but not reciprocity inductions. © 2016 by the American Association for the Advancement of Science; all rights reserved. The title Science is a registered trademark of AAAS.

Hyun S.S.,Pusan National University | Han H.,Dong - A University
International Journal of Contemporary Hospitality Management | Year: 2012

Purpose: The purpose of this research is to create and test a model of a patron's innovativeness formation toward a chain restaurant brand. Design/methodology/approach: A review of the current literature revealed six key determinants in the formation of patrons' innovativeness in the chain restaurant context. Based on theoretical relationships between these constructs, a structural model was proposed. The model was tested utilizing data collected from 433 chain restaurant patrons. Findings: Data analysis indicates that satisfaction and brand attitude positively influence innovativeness, with the impact mediated by advertising effectiveness and perceived risk in a new menu trial. Advertising effectiveness significantly reduced patrons' perceived risk in a new menu trial and thus positively influences innovativeness. Lastly, it was revealed that sales promotions have a strong impact on innovativeness. Research limitations/implications: The findings emphasize the significance of study variables in the formation of patrons' innovativeness in the chain restaurant context. These findings help restaurant practitioners in successful new menu/food product launch. Originality/value: This study is the first to explain the formation of patrons' innovativeness in the chain restaurant industry. Given that a proper understanding of innovativeness is critical to achieving chain restaurants' business success, the model verified in this study may serve as a guideline for practitioners/researchers in this field. © Emerald Group Publishing Limited.

Han L.,Pusan National University | Choi H.-J.,Pusan National University | Choi S.-J.,Pusan National University | Liu B.,Hebei University of Technology | Park D.-W.,Pusan National University
Green Chemistry | Year: 2011

A series of carboxyl-group-functionalized imidazolium-based ionic liquids (CILs) were synthesized and grafted onto silica gel. The catalytic activity of the resulting heterogeneous catalysts toward the synthesis of cyclic carbonate via cycloaddition reactions of epoxide and CO2 was studied. The effect on the reaction of the grafted ILs' structures and the reaction conditions such as reaction temperature, time, pressure, and the amount of catalyst used, were systematically investigated. For comparison, silica-grafted imidazolium-based ILs with and without hydroxyl groups were also used to catalyze cycloaddition reactions. The carboxylic acid group in the catalyst was demonstrated to have a synergistic effect with halide anions. A high yield of cyclic carbonates and excellent selectivity could be obtained under optimized conditions. © The Royal Society of Chemistry.

Kim A.,Pusan National University | Dean A.,U.S. National Institutes of Health
Molecules and Cells | Year: 2012

Abstact: Although linearly distant along mouse chromosome 7 and human chromosome 11, the mammalian β-globin gene is located in close proximity to the upstream locus control region enhancer when it is actively transcribed in the nuclear chromatin environment of erythroid cells. This organization is thought to generate a chromatin loop between the LCR, a powerful enhancer, and active globin genes by extruding intervening regions containing inactive genes. Loop formation in the β-globin locus requires erythroid specific transcriptional activators, co-factors and insulator-related factors. Chromatin structural features such as histone modifications and DNase I hypersensitive site formation as well as nuclear localization are all involved in loop formation in the locus through diverse mechanisms. Current models envision the formation of the loop as a necessary step in globin gene transcription activation, but this has not been definitively established and many questions remain about what is necessary to achieve globin gene transcription activation. © 2012 The Korean Society for Molecular and Cellular Biology and Springer Netherlands.

Seo S.-H.,Pusan National University | Sung H.-W.,Dong - A University
Journal of the European Academy of Dermatology and Venereology | Year: 2012

Background Keloids develop due to the overgrowth of fibrous tissue. Currently, there is no gold standard treatment for keloids and hypertrophic scars (HTS). Their propensity for local invasion and recurrence has prompted many investigations on antineoplastic agents. Objectives To investigate the efficacy of topical and intralesional mitomycin C for the treatment of keloids and HTS. Methods Nine patients with clinically diagnosed keloids and HTS were treated using topical mitomycin C (1 mg/mL) for 3 min after shaving excision. The Vancouver Scars Scale, patient satisfaction, and adverse effects were checked after 6 months. The keloids and HTS were photographed at each monthly visit. Intralesional mitomycin C (1 mg/mL) was administered to study the effect on the regression of keloids in 2 patients. Results Application of mitomycin C to the base of shave-removed keloids and HTS showed good results. Six out of 9 patients were very satisfied with the outcome of treatment; none were disappointed. The results of intralesional mitomycin C treatment were disappointing. Both cases worsened, with increased ulceration after treatment. Conclusions Topical application of mitomycin C following shaving excision was safe and effective for the treatment of keloids and HTS. However, intralesional mitomycin C therapy aggravated both lesions. © 2011 European Academy of Dermatology and Venereology.

Park J.-Y.,Konkuk University | Lee S.-J.,Pusan National University | Lhee S.-H.,Konkuk University | Lee S.-H.,Konkuk University
Arthroscopy - Journal of Arthroscopic and Related Surgery | Year: 2012

Purpose: The follow-up results of bony union after an arthroscopic bony Bankart repair have not been reported. We studied follow-up computed tomography (CT) arthrograms to evaluate radiographic healing of bony Bankart fragments. Methods: Among 41 patients who underwent arthroscopy for a bony Bankart lesion between July 2006 and May 2009, 31 cases in 30 patients who had undergone sequential follow-up CT arthrography preoperatively, at 3 months postoperatively, and at 1 year postoperatively were enrolled. Radiologic patterns of fracture healing were classified into bony healing and fibrous healing. The mean age was 23.4 years, and the mean follow-up was 30.5 months. The mean interval from the first trauma to surgery was 32.5 months, and the mean preoperative dislocation number was 12.1. Results: The mean preoperative glenoid defect was 14.1%. The fracture healing patterns included 26 bony and 5 fibrous unions. There was a significant positive relation between the total dislocation number and the preoperative glenoid defect (P =.003). The proportion of the mean fragment dimension to a circle drawn through the outer cortex of the inferior glenoid was 8.4% preoperatively, 6.6% at 3 months postoperatively, and 6.2% at 1 year postoperatively. The fragment size decreased from that measured preoperatively to the size measured 3 months after surgery (P <.05). However, the fragment size was maintained between 3 months and 1 year postoperatively (P >.05). The mean Rowe score at 1 year postoperatively was 97.2. Conclusions: Follow-up CT arthrographic evaluation showed that small bony Bankart fragments survived without resorption until 1 year postoperatively, even with fibrous union, and that reattached bone fragment fixation to the anatomic position with the labrum could survive. Level of Evidence: Level IV, therapeutic case series. © 2012 by the Arthroscopy Association of North America.

Kim J.-H.,Pusan National University | Lee M.,Inha University | Yang H.,Inha University | Hwang D.-H.,Pusan National University
Journal of Materials Chemistry A | Year: 2014

A high-molecular-weight conjugated polymer consisting of alternating TIPS-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) and diketopyrrolo[3,4-c]pyrrole (DPP) was synthesized by Suzuki cross-coupling and characterized for use in high performance OPVs. Good structural order, self-assembly in spun-cast films, and carrier mobility were observed. PTIPSBDT-DPP showed an OFET hole mobility of up to 0.12 cm2 V -1 s-1. Power conversion efficiencies of up to 8.0% were demonstrated for OPV devices. This journal is © the Partner Organisations 2014.

Lee S.H.,Dong - A University | Cho H.H.,Pusan National University
Fibers and Polymers | Year: 2010

PVDF-CF composite films were prepared using a melt pressing method. The PVDF-CF composite films were cut into rectangular shapes with a gauge length and width of 10 and 5 mm, respectively. The films were drawn using a universal testing machine equipped with a hot chamber. The drawing temperatures and speeds were 50~150 °C and 100~000 %/min, respectively. The crystal structure and physical properties of the resulting PVDF-CF films were investigated by wide angle X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. The crystal form of the initial films was the phase (non polarity, lamellar structure) of PVDF. The maximum draw ratio was 4.2. The drawn PVDF-CF films prepared at 100 °C were mainly the phase (polarity, fibrillar structure) of PVDF. With increasing drawing speeds, the phase became the dominant phase of PVDF in the PVDF-CF films. The thermal properties of the PVDF-CF films improved with increasing drawing temperature, and the dynamic mechanical properties improved with increasing drawing speed. © 2010 The Korean Fiber Society and Springer Netherlands.

Yoon B.-Y.,Pusan National University | Kim Y.-H.,Catholic University of Daegu | Kim N.,Yonsei University | Yun B.-Y.,Pusan National University | And 5 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2013

CueP was initially identified as a copper-resistance gene in Salmonella enterica serovar Typhimurium, which has evolved to survive in the phagosomes of macrophages. Recently, CueP was determined to be a periplasmic copper-binding protein and has been implicated in the transfer of copper ions to SodCII in the periplasm. In this study, the crystal structure of CueP has been determined, revealing a V-shaped dimeric structure. The conserved cysteine and histidine residues are clustered on the surface of one side of the C-terminal domain, suggesting that this cysteine- and histidine-rich region is related to the function of CueP. LC-MS/MS analysis established the presence of a disulfide bond between Cys96 and Cys176 under aerobic conditions. Subsequent biophysical analyses showed that the CueP protein binds copper and zinc, and the mutation of Cys104 to serine (C104S) dramatically reduced the binding affinity for copper and zinc, suggesting that the cysteine- and histidine-rich cluster is responsible for copper binding. This study provides a structural basis for the participation of CueP in the resistance of the intracellular pathogen Salmonella to copper. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved. © 2013.

Yun K.-S.,Pusan National University | Ha K.-J.,Pusan National University | Wang B.,University of Hawaii at Manoa
Geophysical Research Letters | Year: 2010

The impacts of eastern Pacific (EP) and Indian Ocean (IO) warming after the late 1970s on the East Asian climate in July and August were investigated, to understand the distinct impacts of the abovementioned warming on differences in sub-seasonal characteristics. The EP warming induced a strong Pacific-Japan (PJ)-like (tropics-related meridional) pattern during July, but the IO warming preferred a Eurasian (EU)-like wave (extratropics-related zonal) pattern during August. The former is weaker in August and the latter in July. Additionally, the results of perpetual July and August model experiments revealed that these distinct atmospheric responses to the EP and IO warming during July and August, respectively, were caused by different mean thermal states. The difference in the mean thermal states was mainly derived from (1) a warmer ocean and cooler continent in August than in July and (2) a warmer tropics and cooler extratropics in July than in August. © 2010 by the American Geophysical Union. © 2010 by the American Geophysical Union.

Moon J.-Y.,University of Hawaii at Manoa | Wang B.,University of Hawaii at Manoa | Ha K.-J.,Pusan National University | Lee J.-Y.,University of Hawaii at Manoa
Climate Dynamics | Year: 2013

The boreal summer intraseasonal oscillation (BSISO) has strong convective activity centers in Indian (I), Western North Pacific (WNP), and North American (NA) summer monsoon (SM) regions. The present study attempts to reveal BSISO teleconnection patterns associated with these dominant intraseasonal variability centers. During the active phase of ISM, a zonally elongated band of enhanced convection extends from India via the Bay of Bengal and Philippine Sea to tropical central Pacific with suppressed convection over the eastern Pacific near Mexico. The corresponding extratropical circulation anomalies occur along the waveguides generated by the North African-Asian jet and North Atlantic-North European jet. When the tropical convection strengthens over the WNPSM sector, a distinct great circle-like Rossby wave train emanates from the WNP to the western coast of United States (US) with an eastward shift of enhanced meridional circulation. In the active phase of NASM, large anticyclonic anomalies anchor over the western coast of US and eastern Canada and the global teleconnection pattern is similar to that during a break phase of the ISM. Examination of the evolution of the BSISO teleconnection reveals quasi-stationary patterns with preferred centers of teleconnection located at Europe, Russia, central Asia, East Asia, western US, and eastern US and Canada, respectively. Most centers are embedded in the waveguide along the westerly jet stream, but the centers at Europe and Russia occur to the north of the jet-induced waveguide. Eastward propagation of the ISO teleconnection is evident over the Pacific-North America sector. The rainfall anomalies over the elongated band near the monsoon domain over the Indo-western Pacific sector have an opposite tendency with that over the central and southern China, Mexico and southern US, providing a source of intraseasonal predictability to extratropical regions. The BSISO teleconnection along and to the north of the subtropical jet provides a good indication of the surface sir temperature anomalies in the NH extratropics. © 2012 Springer-Verlag.

Kim K.H.,Pusan National University | Abdi S.,University of Houston
Korean Journal of Pain | Year: 2014

Nefopam (NFP) is a non-opioid, non-steroidal, centrally acting analgesic drug that is derivative of the nonsedative benzoxazocine, developed and known in 1960s as fenazocine. Although the mechanisms of analgesic action of NFP are not well understood, they are similar to those of triple neurotransmitter (serotonin, norepinephrine, and dopamine) reuptake inhibitors and anticonvulsants. It has been used mainly as an analgesic drug for nociceptive pain, as well as a treatment for the prevention of postoperative shivering and hiccups. Based on NFP's mechanisms of analgesic action, it is more suitable for the treatment of neuropathic pain. Intravenous administration of NFP should be given in single doses of 20 mg slowly over 15-20 min or with continuous infusion of 60-120 mg/d to minimize adverse effects, such as nausea, cold sweating, dizziness, tachycardia, or drowsiness. The usual dose of oral administration is three to six times per day totaling 90-180 mg. The ceiling effect of its analgesia is uncertain depending on the mechanism of pain relief. In conclusion, the recently discovered dual analgesic mechanisms of action, namely, a) descending pain modulation by triple neurotransmitter reuptake inhibition similar to antidepressants, and b) inhibition of long-term potentiation mediated by NMDA from the inhibition of calcium influx like gabapentinoid anticonvulsants or blockade of voltage-sensitive sodium channels like carbamazepine, enable NFP to be used as a therapeutic agent to treat neuropathic pain. © The Korean Pain Society, 2014.

Kim H.-S.,Pusan National University | Kim H.-S.,Korea Electrotechnology Research Institute | Ryu M.-H.,Korea Electrotechnology Research Institute | Baek J.-W.,Korea Electrotechnology Research Institute | Jung J.-H.,Korea Electrotechnology Research Institute
IEEE Transactions on Power Electronics | Year: 2013

A high-efficiency isolated bidirectional ac-dc converter is proposed for a 380-V dc power distribution system to control bidirectional power flows and to improve its power conversion efficiency. To reduce the switches' losses of the proposed nonisolated full-bridge ac-dc rectifier using an unipolar switching method, switching devices employ insulated-gate bipolar transistors, MOSFETs, and silicon carbide diodes. Using the analysis of the rectifier's operating modes, each switching device can be selected by considering switch stresses. A simple and intuitive frequency detection method for a single-phase synchronous reference frame-phase-locked loop (SRF-PLL) is also proposed using a filter compensator, a fast period detector, and a finite impulse response filter to improve the robustness and accuracy of PLL performance under fundamental frequency variations. In addition, design and control methodology of the bidirectional full-bridge CLLC resonant converter is suggested for the galvanic isolation of the dc distribution system. A dead-band control algorithm for the bidirectional dc-dc converter is developed to smoothly change power conversion directions only using output voltage information. Experimental results will verify the performance of the proposed methods using a 5-kW prototype converter. © 2012 IEEE.

Lee S.-S.,Pusan National University | Lee J.-Y.,University of Hawaii at Manoa | Ha K.-J.,Pusan National University | Wang B.,University of Hawaii at Manoa | Schemm J.K.E.,Climate Prediction Center
Climate Dynamics | Year: 2011

Long-lead prediction of waxing and waning of the Western North Pacific (WNP)-East Asian (EA) summer monsoon (WNP-EASM) precipitation is a major challenge in seasonal time-scale climate prediction. In this study, deficiencies and potential for predicting the WNP-EASM precipitation and circulation one or two seasons ahead were examined using retrospective forecast data for the 26-year period of 1981-2006 from two operational couple models which are the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS) and the Bureau of Meteorology Research Center (BMRC) Predictive Ocean-Atmosphere Model for Australia (POAMA). While both coupled models have difficulty in predicting summer mean precipitation anomalies over the region of interest, even for a 0-month lead forecast, they are capable of predicting zonal wind anomalies at 850 hPa several months ahead and, consequently, satisfactorily predict summer monsoon circulation indices for the EA region (EASMI) and for the WNP region (WNPSMI). It should be noted that the two models' multi-model ensemble (MME) reaches 0.40 of the correlation skill for the EASMI with a January initial condition and 0.75 for the WNPSMI with a February initial condition. Further analysis indicates that prediction reliability of the EASMI is related not only to the preceding El Niño and Southern Oscillation (ENSO) but also to simultaneous local SST variability. On other hand, better prediction of the WNPSMI is accompanied by a more realistic simulation of lead-lag relationship between the index and ENSO. It should also be noted that current coupled models have difficulty in capturing the interannual variability component of the WNP-EASM system which is not correlated with typical ENSO variability. To improve the long-lead seasonal prediction of the WNP-EASM precipitation, a statistical postprocessing was developed based on the multiple linear regression method. The method utilizes the MME prediction of the EASMI and WNPSMI as predictors. It is shown that the statistical postprocessing is able to improve forecast skill for the summer mean precipitation over most of the WNP-EASM region at all forecast leads. It is noteworthy that the MME prediction, after applying statistical postprocessing, shows the best anomaly pattern correlation skill for the EASM precipitation at a 4-month lead (February initial condition) and for the WNPSM precipitation at a 5-month lead (January initial condition), indicating its potential for improving long-lead prediction of the monsoon precipitation. © 2010 Springer-Verlag.

Moon J.-Y.,University of Hawaii at Manoa | Wang B.,University of Hawaii at Manoa | Ha K.-J.,Pusan National University
Climate Dynamics | Year: 2011

The extratropical teleconnections associated with Madden-Julian Oscillation (MJO) are shown to have an action center in the North Pacific where the pressure anomalies have opposite polarities between the Phase 3 (convective Indian Ocean) and Phase 7 (convective western Pacific) of the MJO. The teleconnection in the same phase of MJO may induce opposite anomalies over East Asia and North America between El Niño and La Niña years. During MJO Phase 3, a gigantic North Pacific anticyclonic anomaly occurs during La Niña, making coastal northeast Asia warmer/wetter than normal, but the west US colder/drier; whereas during El Niño the anticyclonic anomaly is confined to the central North Pacific, hence the northwest US experiences warmer than normal weather under influence of a downstream cyclonic anomaly. During Phase 7, an extratropical cyclonic anomaly forms over the northwest Pacific during La Niña due to convective enhancement over the Philippine Sea, causing bitter winter monsoon over Japan; whereas during El Niño, the corresponding cyclonic anomaly shifts to the northeast Pacific due to enhanced convection over the equatorial central Pacific, which causes warm and wet conditions along the west coast of US and Canada. Further, the presence of ENSO-induced seasonal anomalies can significantly modify MJO teleconnection, but the aforementioned MJO teleconnection can still be well identified. During Phase 3, the MJO teleconnection pattern over North Pacific will be counterbalanced (enhanced) by El Niño (La Niña)-induced seasonal mean anomalies. During Phase 7, on the other hand, the MJO teleconnection anomalies in the northeastern Pacific will be enhanced during El Niño but reduced during La Niña; thereby the impacts of MJO teleconnection on the North America is expected to be stronger during El Niño than during La Niña. © 2010 Springer-Verlag.

Kim H.-S.,Pusan National University | Kim H.-S.,Korea Electrotechnology Research Institute | Jung J.-H.,Korea Electrotechnology Research Institute | Baek J.-W.,Korea Electrotechnology Research Institute | Kim H.-J.,Pusan National University
IEEE Transactions on Industrial Electronics | Year: 2013

This paper presents a multioutput converter using an asymmetrical pulsewidth modulation half-bridge flyback topology employing a parallel-series-connected transformer. Compared to conventional multioutput topologies, the proposed converter operates using a single-output controller without the need for additional control loops and devices. In order to solve the cross-regulation problem, the output stages of the proposed converter are stacked in series. In addition, the voltage regulation of the proposed multioutput converter is improved through the analysis of its resonant characteristics under load variations and minimizing the secondary conduction loss. The proposed multioutput converter shows excellent performance in terms of its output regulation from no-load to full-load conditions and good cross regulation under high output currents. The design methodology and performance of the proposed converter have been verified through experimentation employing a 110-W (3.3 V/16 A, 5 V/12 A) prototype converter. © 1982-2012 IEEE.

Salehiyan R.,Pusan National University | Yoo Y.,Korea Research Institute of Chemical Technology | Choi W.J.,Korea Research Institute of Chemical Technology | Hyun K.,Pusan National University
Macromolecules | Year: 2014

Linear and nonlinear viscoelastic properties under dynamic oscillatory shear flow were used to investigate the effects of compatibilization on polypropylene (PP)/polystyrene (PS) blends. Two different nanoparticles (organo-modified clay and fumed silica) were used at various concentrations. To analyze nonlinear stress under large amplitude oscillatory shear (LAOS) flow, nonlinearity (I3/1) was calculated from FT-rheology. To quantify the degree of dispersion of different particles at various concentrations, a new parameter, nonlinear-linear viscoelastic ratio (NLR ≡ normalized nonlinear viscoelasticity/normalized linear viscoelasticity), was used. The relationship was determined between NLR value and PS droplet size in the PP matrix. From the TEM images, clay was located mostly at the interface or partially inside the PS drops, thereby reinforcing the compatibilization effect. Therefore, clay increased the dispersion morphologies of the PP/PS blends. In contrast, fumed silica was located mostly inside the PS droplets, which means the morphologies of PP/PS blends were not improved. Linear viscoelasticities of both PP/PS/clay and PP/PS/silica showed improvements at elevated particle concentrations. NLR values for the PP/PS/Clay blends were larger than 1 (NLR > 1), whereas NLR values for the PP/PS/silica blends were less than 1 (NLR < 1). Therefore, NLR could be classified into two categories depending on morphology. Based on these results, NLR can be used to distinguish between the effects of two different types of nanoparticles on the morphologies of PP/PS blends. © 2014 American Chemical Society.

Lee B.H.,Gwangju Institute of Science and Technology | Jung I.H.,Korea Advanced Institute of Science and Technology | Woo H.Y.,Pusan National University | Shim H.-K.,Korea Advanced Institute of Science and Technology | And 2 more authors.
Advanced Functional Materials | Year: 2014

Despite the excellent work function adjustability of conjugated polyelectrolytes (CPEs), which induce a vacuum level shift via the formation of permanent dipoles at the CPE/metal electrode interface, the exact mechanism of electron injection through the CPE electron transport layer (ETL) remains unclear. In particular, understanding the ionic motion within the CPE ETLs when overcoming the sizable injection barrier is a significant challenge. Because the ionic functionality of CPEs is a key component for such functions, a rigorous analysis using highly controlled ion density (ID) in CPEs is crucial for understanding the underlying mechanism. Here, by introducing a new series of CPEs with various numbers of ionic functionalities, energy level tuning at such an interface can be determined directly by adjusting the ID in the CPEs. More importantly, these series CPEs indicate that two different mechanisms must be invoked according to the CPE thickness. The formation of permanent interfacial dipoles is critical with respect to electron injection through CPE ETL (≤ 10 nm, quantum mechanical tunneling limit), whereas electron injection through thick CPE ETL (20-30 nm) is dominated by the reorientation of the ionic side chains under a given electric field. An electron injection mechanism for conjugated polyelectrolyte (CPE) electron transport layers in organic electronic devices is demonstrated by introducing a new series of CPEs with various numbers of ionic functionalities. Energy level tuning at the CPE/metal interface can be determined directly by adjusting ion density in the CPEs. Thickness-dependent electron injection characteristics indicate that two different mechanisms must be invoked according to the CPE thickness. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rhim J.-W.,Mokpo National University | Park H.-M.,Michigan State University | Ha C.-S.,Pusan National University
Progress in Polymer Science | Year: 2013

There is growing interest in developing bio-based polymers and innovative process technologies that can reduce the dependence on fossil fuel and move to a sustainable materials basis. Bio-nanocomposites open an opportunity for the use of new, high performance, light weight green nanocomposite materials making them to replace conventional non-biodegradable petroleum-based plastic packaging materials. So far, the most studied bio-nanocomposites suitable for packaging applications are starch and cellulose derivatives, polylactic acid (PLA), polycaprolactone (PCL), poly(butylene succinate) (PBS) and polyhydroxybutyrate (PHB). The most promising nanoscale fillers are layered silicate nanoclays such as montmorillonite and kaolinite. In food packaging, a major emphasis is on the development of high barrier properties against the diffusion of oxygen, carbon dioxide, flavor compounds, and water vapor. Moreover, several nanostructures can be useful to provide active and/or smart properties to food packaging systems, as exemplified by antimicrobial properties, oxygen scavenging ability, enzyme immobilization, or indication of the degree of exposure to some detrimental factors such as inadequate temperatures or oxygen levels. Challenges remain in increasing the compatibility between clays and polymers and reaching complete dispersion of nanoparticles. This review focuses on the enhancement of packaging performance of the green materials as well as their biodegradability, antimicrobial properties, and mechanical and thermal properties for food packaging application. The preparation, characterization and application of biopolymer-based nanocomposites with organic layered silicate and other fillers, and their application in the food packaging sector are also discussed. © 2013 Elsevier Ltd.

Yang C.,Pusan National University | Kim E.,Chosun University | Pak Y.,Pusan National University
Nucleic Acids Research | Year: 2015

Houghton (HG) base pairing plays a central role in the DNA binding of proteins and small ligands. Probing detailed transition mechanism from Watson-Crick (WC) to HG base pair (bp) formation in duplex DNAs is of fundamental importance in terms of revealing intrinsic functions of double helical DNAs beyond their sequence determined functions. We investigated a free energy landscape of a free B-DNA with an adenosine-thymine (A-T) rich sequence to probe its conformational transition pathways from WC to HG base pairing. The free energy landscape was computed with a state-of-art two-dimensional umbrella molecular dynamics simulation at the all-atom level. The present simulation showed that in an isolated duplex DNA, the spontaneous transition from WC to HG bp takes place via multiple pathways. Notably, base flipping into the major and minor grooves was found to play an important role in forming these multiple transition pathways. This finding suggests that naked B-DNA under normal conditions has an inherent ability to form HG bps via spontaneous base opening events. © 2015 The Author(s).

Wang B.,University of Hawaii at Manoa | Yim S.-Y.,University of Hawaii at Manoa | Lee J.-Y.,University of Hawaii at Manoa | Liu J.,Nanjing Normal University | Ha K.-J.,Pusan National University
Climate Dynamics | Year: 2014

We investigate the future changes of Asian-Australian monsoon (AAM) system projected by 20 climate models that participated in the phase five of the Coupled Model Intercomparison Project (CMIP5). A metrics for evaluation of the model's performance on AAM precipitation climatology and variability is used to select a subset of seven best models. The CMIP5 models are more skillful than the CMIP3 models in terms of the AAM metrics. The future projections made by the selected multi-model mean suggest the following changes by the end of the 21st century. (1) The total AAM precipitation (as well as the land and oceanic components) will increase significantly (by 4.5 %/°C) mainly due to the increases in Indian summer monsoon (5.0 %/°C) and East Asian summer monsoon (6.4 %/°C) rainfall; the Australian summer monsoon rainfall will increase moderately by 2.6 %/°C. The "warm land-cool ocean" favors the entire AAM precipitation increase by generation of an east-west asymmetry in the sea level pressure field. On the other hand, the warm Northern Hemisphere-cool Southern Hemisphere induced hemispheric SLP difference favors the ASM but reduces the Australian summer monsoon rainfall. The combined effects explain the differences between the Asian and Australian monsoon changes. (2) The low-level tropical AAM circulation will weaken significantly (by 2.3 %/°C) due to atmospheric stabilization that overrides the effect of increasing moisture convergence. Different from the CMIP3 analysis, the EA subtropical summer monsoon circulation will increase by 4.4 %/°C. (3) The Asian monsoon domain over the land area will expand by about 10 %. (4) The spatial structures of the leading mode of interannual variation of AAM precipitation will not change appreciably but the ENSO-AAM relationship will be significantly enhanced. © 2013 The Author(s).

Lee K.-J.,Pusan National University | Lee K.-J.,Korea Electrotechnology Research Institute | Lee J.-P.,Korea Electrotechnology Research Institute | Shin D.,Pusan National University | And 3 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

The amount of distributed energy resources (DERs) has increased constantly worldwide. The power ratings of DERs have become considerably high, as required by the new grid code requirement. To follow the grid code and optimize the function of grid-connected inverters based on DERs, a phase-locked loop (PLL) is essential for detecting the grid phase angle accurately when the grid voltage is polluted by harmonics and imbalance. This paper proposes a novel low-pass notch filter PLL (LPN-PLL) control strategy to synchronize with the true phase angle of the grid instead of using a conventional synchronous reference frame PLL (SRF-PLL), which requires a d-q-axis transformation of three-phase voltage and a proportional-integral controller. The proposed LPN-PLL is an upgraded version of the PLL method using the fast Fourier transform concept (FFT-PLL) which is robust to the harmonics and imbalance of the grid voltage. The proposed PLL algorithm was compared with conventional SRF-PLL and FFT-PLL and was implemented digitally using a digital signal processor TMS320F28335. A 10-kW three-phase grid-connected inverter was set, and a verification experiment was performed, showing the high performance and robustness of the proposal under low-voltage ride-through operation. © 1982-2012 IEEE.

Kim H.,Pusan National University | Son J.,LS Industrial System | Lee J.,Pusan National University
IEEE Transactions on Industrial Electronics | Year: 2011

This paper proposes a sensorless speed control strategy for a permanent-magnet synchronous motor (PMSM) based on a new sliding-mode observer (SMO), which substitutes a sigmoid function for the signum function with a variable boundary layer. In order to apply a sensorless PMSM control which is robust against parameter fluctuations and disturbances, a high-speed SMO is proposed, which estimates the rotor position and the angular velocity from the back EMF. In the conventional SMO, a low-pass filter and an additional position compensation of the rotor are used to reduce the chattering problem that is commonly found in the SMO using the signum function. In order to overcome the time delay caused by the low-pass filter, in this research, a sigmoid function is used for the switching function instead of the signum function. Also, the variation in the stator resistance is estimated to improve the steady-state performance of the SMO. The stability of the proposed SMO was verified using the Lyapunov second method to determine the observer gain. The validity of the proposed high-speed PMSM sensorless velocity control has been demonstrated with simulations and real experiments. © 2010 IEEE.

The current study was aimed to investigate the clinical value of intratumoral heterogeneity of F-18 FDG uptake for characterization of thyroid nodule (TN) with inconclusive fine-needle aspiration biopsy (FNAB) results. The current study enrolled 200 patients who showed F-18 FDG incidentaloma and were performed FNAB. The intratumoral heterogeneity of F-18 FDG uptake was represented as the heterogeneity factor (HF), defined as the derivative (dV/dT) of a volume-threshold function for a primary tumor. The diagnostic and predictive values of HF and F-18 FDG PET/CT parameters were evaluated for characterization of inconclusive FNAB results. Among F-18 FDG PET/CT parameters, SUVmax, MTV, and TLG of malignant group were statistically higher than those of Bethesda category of suspicious malignant group. However, HF values were not statistically different between the groups of Bethesda categories (Kruskal–Wallis statistics, 9.924; p = 0.0774). In ROC analysis, when HF > 2.751 was used as cut-off value, the sensitivity and specificity for prediction of malignant TN were 100 % (95 % CI 69.2–100 %) and 60 % (95 % CI 42.1–76.1 %), respectively. The AUC was 0.826 (95 % CI 0.684–0.922) and standard error was 0.0648 (p < 0.0001). In conclusion, the intratumoral heterogeneity of F-18 FDG uptake represented by HF could be a predictor for characterization of TN with inconclusive FNAB results. Additional large population-based prospective studies are needed to validate the diagnostic utility of HF of F-18 FDG PET/CT. © 2015, Springer Science+Business Media New York.

Kim E.,Chosun University | Kim E.,Korea Institute of Science and Technology | Yang C.,Pusan National University | Pak Y.,Pusan National University
Journal of Chemical Theory and Computation | Year: 2012

Thrombin-binding aptamer (TBA-15) is a single-stranded 15-mer oligonucleotide that has a wide range of biomedical applications. In the presence of metal cations of proper sizes, this aptamer displays G-quadruplexes with a single cation enclosed at its central binding site when it is completely folded. To understand how this aptamer folds into its stable three-dimensional structure in the presence of K + ions, we carried out free-energy calculations using the state-of-art replica exchange molecular dynamics simulation (REMD) at the all-atom level. The resulting free energy map revealed that TBA-15 follows a two-state folding behavior with a substantially large folding barrier of 6 kcal/mol at ambient temperature. Our simulation showed that the intervening TGT-loop, which is located in the middle of the TBA-15 sequence, virtually remains intact regardless of folding and unfolding states. Furthermore, in the conserved TGT-loop structure, the base-pair stacking of G8 and T9 induces the native-like base orientations of G6 and G10 pertaining to the upper G-quadrant. This stacking interaction enhances the loop stability and reduces its dynamic fluctuations. Interestingly, for the G-stem to fold into its native state, the aggregation of the G8 and T9 residues in the TGT-loop is a key step for initiating the folding event of the G-stem by capturing a bulky cation. © 2012 American Chemical Society.

Lim S.-C.,Chosun University | Choi J.E.,Chosun University | Kang H.S.,Pusan National University | Si H.,Chosun University
International Journal of Cancer | Year: 2010

Hepatocellular carcinoma (HCC) is resistant to chemotherapy. Recently, however, several oxaliplatin-based combinatorial treatments have shown a promising anti-tumor activity in patients with HCC. Presently, we demonstrate that oxaliplatin triggers necrosis more than apoptosis in HepG2, SK-Hep1, SNU-423 and Hep3B HCC cells, while mainly inducing apoptosis in HCT116 and HT29 colon cancer cells. Interestingly, ursodeoxycholic acid (UDCA), a less hydrophobic bile acid that can suppress carcinogenesis, shifted oxaliplatin-induced necrosis to apoptosis in HepG2 cells. The same effect was produced by hydrophilic bile acids (tauroursodeoxycholic acid and taurohyodeoxycholic acid), but not by highly hydrophobic bile acids (deoxycholic acid and chenodeoxycholic acid). UDCA also triggered the necrosis-to-apoptosis switch when cotreated with other platinum-based chemotherapeutic drugs including cisplatin and carboplatin, suggesting that the cell death mode switching effect of UDCA is a general phenomenon when combined with platinum drugs. Oxaliplatin produced high level of reactive oxygen species (ROS) in HepG2 cells and UDCA significantly reduced oxaliplatin-induced ROS generation. In addition, N-acetyl-L-cysteine and the superoxide scavengers butylated hydroxyanisole and dihydroxybenzene-3,5-disulfonic acid attenuated necrosis, indicating a critical role(s) of ROS in occurrence of necrotic death. Apoptosis induced by combined treatment appeared to be mediated by p53-caspase 8-caspase 3 pathway. In conclusion, UDCA switches oxaliplatin-induced necrosis to apoptosis via inhibition of ROS production and activation of the p53-caspase 8 pathway in HepG2 cells. As necrosis and subsequent inflammation are implicated in tumor progression and malignancy, our results imply a potential improved efficacy of UDCA-combined chemotherapy in HCC by reducing inflammatory responses that may be triggered by oxaliplatin. © 2009 UICC.

Moon J.-Y.,University of Hawaii at Manoa | Wang B.,University of Hawaii at Manoa | Ha K.-J.,Pusan National University
Journal of Climate | Year: 2012

During the winter of 2009/10, a number of record-breaking snowfall events registered in the eastern United States are shown to have been modulated by the pulsation of tropical MJO through an atmospheric teleconnection pattern. The intraseasonal variability over the eastern subtropical Pacific near Mexico (the equatorial central Pacific) had reached themaximum(second largest) strength since 1979/80. Fromlate December to mid-February, the convection over these two regions experienced a remarkable wet-dry-wet cycle; correspondingly, the daily snowfall over the eastern United States also exhibited a wet-dry-wet cycle. As the MJO convection reached the central Pacific, a teleconnection pattern extended to North America, resulting in a westward-tilted deep anomalous trough anchored over the eastern United States, producing a low-level pressure dipole anomaly with an anticyclone (cyclone) centered at the U.S. West (East) Coast. The convection over the Indian Ocean varied in phase with the central Pacific convection, reinforcing the extratropical atmospheric teleconnection pattern. As a result, the enhanced high-latitude cold air penetrated southward, affecting the central and eastern United States. Meanwhile, warmer moist air was transported from the tropical central Pacific by the existing El Niño through Mexico to the southernUnited States along with the upper-level subtropical westerly jet, which extended from the subtropical Pacific to theAtlanticOcean. As such, the eastern United States was located in a convergence zone between the enhanced cold air from the high latitude and the warm, moist air supplied from the subtropics, resulting in favorable conditions for extremely heavy snowfall. © 2012 American Meteorological Society.

Sunesh C.D.,Pusan National University | Mathai G.,Sacred Heart College | Choe Y.,Pusan National University
ACS Applied Materials and Interfaces | Year: 2014

A series of cationic iridium complexes (1-6) were synthesized using alkylated imidazole-based ancillary ligands, and the photophysical and electrochemical properties of these complexes were subsequently evaluated. Light-emitting electrochemical cells (LECs) were fabricated from these complexes, and the effects of the alkyl chain length on the electroluminescent properties of the devices were investigated. The LECs based on these complexes resulted in yellow emission (complexes 1, 3, and 5) and green emission (complexes 2, 4, and 6) with Commission Internationale de L'Eclairage (CIE) coordinates of (0.49, 0.50) and (0.33, 0.59), respectively. Our results indicate that the luminance and efficiency of the LECs can consistently be enhanced by increasing the alkyl chain length of the iridium complexes as a result of suppressed intermolecular interaction and self-quenching. Subsequently, a high luminance of 7309 cd m-2 and current efficiency of 3.85 cd A-1 were achieved for the LECs based on complex 5. © 2014 American Chemical Society.

Zhang L.,Nanjing University of Aeronautics and Astronautics | Wang J.,Nanjing University of Aeronautics and Astronautics | Zhu J.,Nanjing University of Aeronautics and Astronautics | Zhang X.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

A 3D hybrid nickel-aluminum layered double hydroxide (NiAl-LDH)-graphene nanosheets (GNS) composite as a supercapacitor material has been fabricated by in situ deposition of LDH nanosheets on graphene oxide (GO) through a liquid phase deposition method. The results reveal that NiAl-LDH homogeneously grew on the surface of GNS as spacers to keep the neighboring sheets separate. Optimum effects could be achieved when feeding ratio, reaction time and temperature are tuned. The obtained porous GNS/NiAl-LDH composite exhibited high-capacitance performance with a specific capacitance of 1255.8 F g-1 at a current density of 1 A g-1 and 755.6 F g-1 at 6 A g-1, respectively. Moreover, the composite exhibited excellent cycling performance with an increase of 6% capacitance compared with the initial capacitance after 1500 cycle tests. Such high specific capacitance, rate capability and exceptional cycling ability of the composite offered great promise in energy storage device applications. © 2013 The Royal Society of Chemistry.

Ren L.,City University of Hong Kong | Hui K.S.,City University of Hong Kong | Hui K.S.,Hanyang University | Hui K.N.,Pusan National University
Journal of Materials Chemistry A | Year: 2013

In this work, we report a low-cost technique for fabrication of a simple three-dimensional (3D) free-standing nickel nanoparticle/graphene aerogel with a graphene sheet network. The 3D composite architecture was formed through the self-assembly aggregation of graphene accompanied by nickel nanoparticle in situ loading on the graphene sheet during the hydrothermal reduction of graphene oxide and Ni ions. The obtained composite architecture was characterized using X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. The electrocatalytic properties of the as-synthesized Ni/graphene aerogel for ethanol oxidation were investigated using cyclic voltammetry and chronoamperometry. A high peak current density of about 6 mA cm-2 for ethanol oxidation was recorded during ethanol oxidation under the test condition of adding 0.1 M ethanol in 0.1 M NaOH solution. This result revealed excellent electrocatalytic activity for ethanol oxidation, which shows great potential for direct application in ethanol fuel cells. This study provides a guide to preparing well-defined sponge-like three-dimensional metallic/graphene nanoarchitectures for fuel cell applications. This journal is © 2013 The Royal Society of Chemistry.

Roshan K.R.,Pusan National University | Mathai G.,Sacred Heart College | Kim J.,Pusan National University | Tharun J.,Pusan National University | And 2 more authors.
Green Chemistry | Year: 2012

A promising application of carboxymethyl cellulose (CMC), which is a congener of the cellulose family, as a supporting material for a variety of imidazolium based ionic liquid catalysts in the chemical fixation of CO 2 has been studied here. The ionic liquids immobilized on the carboxymethyl cellulose (CMIL) showed high catalytic activity and selectivity in the cycloaddition of carbon dioxide with propylene oxide (PO) resulting in propylene carbonate (PC) under mild and solvent free conditions. A new pathway was proposed based on the density functional theory (DFT) calculations performed at the B3LYP/6-31G (d,p) level, where the carboxyl and hydroxyl moieties on the CMC were found to act synergistically with the halide ions to eventuate in the cycloaddition reaction. The carboxyl group entities on the carboxymethyl cellulose support supposedly stabilize the product complex via strong hydrogen bonds, thereby promoting the reaction. The catalyst system also displayed good reusability. © 2012 The Royal Society of Chemistry.

Woon Kim Y.,Pusan National University | Kim S.,Pusan National University | Geun Kim C.,Hanyang University | Kim A.,Pusan National University
Nucleic Acids Research | Year: 2011

GATA-1 and NF-E2 are erythroid specific activators that bind to the β-globin locus. To explore the roles of these activators in transcription of the human fetal stage specific γ-globin genes, we reduced GATA-1 and p45/NF-E2 using shRNA in erythroid K562 cells. GATA-1 or p45/NF-E2 knockdown inhibited the transcription of the γ-globin genes, hypersensitive site (HS) formation in the LCR and chromatin loop formation of the β-globin locus, but histone acetylation across the locus was decreased only in the case of GATA-1 knockdown. In p45/NF-E2 knockdown cells, GATA-1 binding was maintained at the LCR HSs and γ-globin promoter, but NF-E2 binding at the LCR HSs was reduced by GATA-1 knockdown regardless of the amount of p45/NF-E2 in K562 cells. These results indicate that histone acetylation is dependent on GATA-1 binding, but the binding of GATA-1 is not sufficient for the γ-globin transcription, HS formation and chromatin loop formation and NF-E2 is required. This idea is supported by the distinctive binding pattern of CBP and Brg1 in the β-globin locus. Furthermore GATA-1-dependent loop formation between HS5 and 3′HS1 suggests correlation between histone modifications and chromatin looping. © 2011 The Author(s).

Tharun J.,Pusan National University | Mathai G.,Sacred Heart College | Kathalikkattil A.C.,Pusan National University | Roshan R.,Pusan National University | And 2 more authors.
Green Chemistry | Year: 2013

An environment-friendly synthesis of cyclic carbonates from CO2 and epoxides with a HCOOH/KI catalytic system was performed in a microwave reactor. Various epoxide substrates were subjected to microwave irradiated cycloaddition using a HCOOH/KI catalyst. The effects of reaction parameters like catalyst composition, microwave power, CO2 pressure, and reaction time have been investigated. The synergistic influence of the COOH/KI catalyst in the reaction has been compared with that of an OH/KI system and was theoretically simulated using density functional theory. © 2013 The Royal Society of Chemistry.

Ryu C.-Y.,Hanyang University | Hyun C.H.,Daegu University | Lee C.-H.,Pusan National University
Physical Review C - Nuclear Physics | Year: 2011

In this work, masses and radii of neutron stars are considered to investigate the effect of nuclear symmetry energy on astrophysical observables. A relativistic mean-field model with density-dependent meson-baryon coupling constants is employed in describing the equation of state of dense nuclear matter, and the density dependencies of the symmetry energies are quoted from the recent phenomenological formulas obtained from heavy-ion data at subnuclear saturation densities. Since hyperons can take part in the β-equilibrium of the dense matter inside neutron stars, we include hyperons in our estimation and their roles are discussed in combination with that of the nuclear symmetry energy. © 2011 American Physical Society.

Yun K.-S.,Pusan National University | Yeh S.-W.,Hanyang University | Ha K.-J.,Pusan National University
Journal of Geophysical Research: Atmospheres | Year: 2013

The distinct impact of tropical Indian Ocean (IO) and western Pacific (WP) sea surface temperatures (SSTs) after the El Niño winter has been investigated in relation to the summer North Pacific high (NPH) and western North Pacific subtropical high (WNPSH). After the El Niño winter, warming of the IO leads to a summer eastern Pacific (EP) SST anomaly distinct from the cooling of WP; EP cooling occurs in the extreme IO warming case and EP warming in the WP cooling case. Both the warming of the IO and cooling of the WP are responsible for the development of the WNPSH, whereas the summer EP cooling induces an enhanced NPH, especially if it coexists with IO warming. The IO warming triggers an abrupt termination of the El Niño event by causing the easterly anomaly in the WP, which leads to the coexistence of IO warming and EP cooling during the boreal summer. The tropical EP cooling may change the North Pacific SST anomalies via the atmospheric bridge and consequently strengthen the extratropical NPH. The experimental results, which have been obtained from the use of atmospheric general circulation model, support the distinct roles of EP cooling on the NPH and of IO warming and WP cooling on the WNPSH. This finding suggests that the combined effect of IO warming and EP cooling generates a coupled pattern of NPH and WNPSH. Key PointsIO warming and WP cooling induce the development of the WNPSHIO warming-related summer EP cooling induces an enhanced NPHIO warming and EP cooling generate a coupled pattern of NPH and WNPSH ©2013. American Geophysical Union. All Rights Reserved.

Jeong T.-G.,Pusan National University | Moon Y.H.,Pusan National University | Chun H.-H.,Pusan National University | Kim H.S.,Korea Institute of Science and Technology | And 2 more authors.
Chemical Communications | Year: 2013

Herein, we report a cheap and simple approach to solve the polysulfide dissolution problem in lithium sulfur batteries. It was interestingly revealed that a simple insertion of acetylene black mesh enabled us to obtain the capacity of 1491 mA h g-1 at initial discharge and 1062 mA h g -1 after 50 cycles. © 2013 The Royal Society of Chemistry.

Pu X.-S.,Advanced Drive Technology Company | Nguyen T.H.,Yeungnam University | Lee D.-C.,Yeungnam University | Lee K.-B.,Ajou University | Kim J.-M.,Pusan National University
IEEE Transactions on Industrial Electronics | Year: 2013

In this paper, a novel scheme for the estimation of the equivalent series resistance (ESR) of the dc-link electrolytic capacitor in three-phase ac/dc pulsewidth-modulation converters is proposed for condition monitoring. First, a controlled ac current component is injected into the input. Then, it induces ac voltage ripples on the dc output. By manipulating these ac voltage and current components with digital filters, the value of the ESR can be calculated, where the recursive least squares algorithm is used for reliable estimation results. In addition, the value of the ESR is corrected by considering the temperature effect, for which a simple temperature-sensing circuit has been designed. The simulation and experimental results show that the estimation error of the ESR is within a reasonable range, thereby enabling the determination of the appropriate time for the replacement of the capacitor. © 1982-2012 IEEE.

Park K.-Y.,Pusan National University | Jeong J.-K.,Pusan National University | Lee Y.-E.,Wonkwang University | Daily J.W.,Daily Manufacturing Inc.
Journal of Medicinal Food | Year: 2014

Kimchi is a traditional Korean food manufactured by fermenting vegetables with probiotic lactic acid bacteria (LAB). Many bacteria are involved in the fermentation of kimchi, but LAB become dominant while the putrefactive bacteria are suppressed during salting of baechu cabbage and the fermentation. The addition of other subingredients and formation of fermentation byproducts of LAB promote the fermentation process of LAB to eventually lead to eradication of putrefactive- and pathogenic bacteria, and also increase the functionalities of kimchi. Accordingly, kimchi can be considered a vegetable probiotic food that contributes health benefits in a similar manner as yogurt as a dairy probiotic food. Further, the major ingredients of kimchi are cruciferous vegetables; and other healthy functional foods such as garlic, ginger, red pepper powder, and so on are added to kimchi as subingredients. As all of these ingredients undergo fermentation by LAB, kimchi is regarded as a source of LAB; and the fermentative byproducts from the functional ingredients significantly boost its functionality. Because kimchi is both tasty and highly functional, it is typically served with steamed rice at every Korean meal. Health functionality of kimchi, based upon our research and that of other, includes anticancer, antiobesity, anticonstipation, colorectal health promotion, probiotic properties, cholesterol reduction, fibrolytic effect, antioxidative and antiaging properties, brain health promotion, immune promotion, and skin health promotion. In this review we describe the method of kimchi manufacture, fermentation, health functionalities of kimchi and the probiotic properties of its LAB. © Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition 2014.

Sunesh C.D.,Pusan National University | Mathai G.,Sacred Heart College | Choe Y.,Pusan National University
Organic Electronics: physics, materials, applications | Year: 2014

The ionic iridium complexes, [Ir(ppy)2(EP-Imid)]PF6 (Complex 1) and [Ir(dfppy)2(EP-Imid)]PF6 (Complex 2) are used as the light-emitting material for the fabrication of light-emitting electrochemical cells (LECs). These complexes have been synthesized, employing 2-(4-ethyl-2-pyridyl)-1H-imidazole (EP-Imid) as the ancillary ligand, 2-phenylpyridine (ppy) and 2-(2,4-difluorophenyl)pyridine (dfppy) as the cyclometalated ligands, which were characterized by various spectroscopic, photophysical and electrochemical methods. The photoluminescence (PL) emission spectra in acetonitrile solution show blue-green and blue light emission for Complexes 1 and 2 respectively. However, LECs incorporating these complexes resulted in green (522 nm) light emission for Complex 1 with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.56) and blue-green (500 nm) light emission for Complex 2 with the CIE coordinates of (0.24, 0.44). Using Complex 1, a maximum luminance of 1191 cd m-2 and current efficiency of 1.0 cd A-1 are obtained while that of Complex 2 are 741 cd m-2 and 0.88 cd A-1 respectively. © 2013 Elsevier B.V. All rights reserved.

Park J.J.,Pusan National University | Kim K.-H.,Korea Advanced Institute of Science and Technology | Sagawa T.,Kyoto University | Kim S.W.,Pusan National University
Physical Review Letters | Year: 2013

The key question of this Letter is whether work can be extracted from a heat engine by using purely quantum mechanical information. If the answer is yes, what is its mathematical formula? First, by using a bipartite memory we show that the work extractable from a heat engine is bounded not only by the free energy change and the sum of the entropy change of an individual memory but also by the change of quantum mutual information contained inside the memory. We then find that the engine can be driven by purely quantum information, expressed as the so-called quantum discord, forming a part of the quantum mutual information. To confirm it, as a physical example we present the Szilard engine containing a diatomic molecule with a semipermeable wall. © 2013 American Physical Society.

Zhao H.,City University of Hong Kong | Hui K.S.,Hanyang University | Hui K.N.,Pusan National University
Carbon | Year: 2014

We reported on the facile synthesis of N-doped multilayer graphene (N-MLG) from milk powder that uses melamine as a nitrogen-doping source with Fe 2+ ions as catalytic growth agents. We showed that milk powder could be used as a precursor for large-scale N-MLG synthesis through heat treatment at 1000 °C under N2 atmosphere for 45-120 min. In addition, heating time has a remarkable effect on N content and type in N-MLG. The resulting N-MLG exhibited higher catalytic activity than undoped graphene and carbon nanotubes (CNTs), as well as comparable catalytic activity to commercial Pt/C catalyst toward oxygen reduction reaction (ORR). Furthermore, the catalytic activity was sensitive to N content and type, particularly the ratio of pyridinic-N to total N atoms. Results showed that Fe atoms in N-MLG were found to function not as synergetic catalysts for ORR but as catalytic growth agents for N-MLG formation, thereby promoting and stabilizing N atoms. The present method could lead to the synthesis of bulk amounts of N-MLG, which is promising for applications in electrochemical energy devices, such as fuel cells and metal-air batteries. © 2014 Elsevier Ltd. All rights reserved.

Huang E.,Ottawa Hospital Research Institute | Qu D.,Ottawa Hospital Research Institute | Zhang Y.,Ottawa Hospital Research Institute | Venderova K.,Ottawa Hospital Research Institute | And 6 more authors.
Nature Cell Biology | Year: 2010

Accumulating evidence suggests that deregulated cyclin-dependent kinase 5 (Cdk5) plays a critical part in neuronal death. However, the pathogenic targets of Cdk5 are not fully defined. Here we demonstrate that the Cdk5 activator p35 interacts directly with apurinic/apyrimidinic endonuclease 1 (Ape1), a protein crucial for base excision repair (BER) following DNA damage. Cdk5 complexes phosphorylate Ape1 at Thr 232 and thereby reduces its apurinic/apyrimidinic (AP) endonuclease activity. Ape1 phosphorylation is dependent on Cdk5 in in vitro and in vivo. The reduced endonuclease activity of phosphorylated Ape1 results in accumulation of DNA damage and contributes to neuronal death. Overexpression of Ape1WT and Ape1T232A, but not the phosphorylation mimic Ape1T232E, protects neurons against MPP +/MPTP. Loss of Ape1 sensitizes neurons to death. Importantly, increased phosphorylated Ape1 was also observed in post-mortem brain tissue from patients with Parkinson's and Alzheimer's diseases, suggesting a potential link between Ape1 phosphorylation and the pathogenesis of neurodegenerative diseases. © 2010 Macmillan Publishers Limited. All rights reserved.

Kang S.H.,Pusan National University | Cheong C.,Xi'an Jiaotong - Liverpool University | Yoon S.-M.,Pusan National University
Physica A: Statistical Mechanics and its Applications | Year: 2013

This study provides empirical evidence of the relationship between spot and futures markets in Korea. In particular, the study focuses on the volatility spillover relationship between spot and futures markets by using three high-frequency (10 min, 30 min, and 1 h time-scales) intraday data sets of KOSPI 200 spot and futures contracts. The results indicate a strong bi-directional causal relationship between futures and spot markets, suggesting that return volatility in the spot market can influence that in the futures market and vice versa. Thus, the results indicate that new information is reflected in futures and spot markets simultaneously. This bi-directional causal relationship provides market participants with important guidance on understanding the intraday information transmission between the two markets. Thus, on a given trading day, there may be sudden and sharp increases or decreases in return volatility in the Korean stock market as a result of positive feedback and synchronization of spot and futures markets. © 2013 Elsevier B.V. All rights reserved.

Song H.,Pusan National University | Yun S.-W.,Pusan National University | Chun H.-H.,Pusan National University | Kim M.-G.,Pohang Accelerator Laboratory | And 4 more authors.
Energy and Environmental Science | Year: 2012

Since one of the main drawbacks of Li4Ti5O 12 as a negative-electrode material is its low electronic conductivity, several researchers have attempted to improve the conductivity by narrowing the band gap through transition-metal doping. Herein, we report another, more significant effect of doping in addition to the band gap narrowing, namely, an anomalous decrease in the structural disorder in Li 4Ti5O12 upon Cr3+-ion doping. Although it is generally recognized that doping with heterogeneous elements increases the structural disorder, the Cr3+-ion doping in Li 4Ti5O12 demonstrated an unexpected structural phenomenon. From the results of various structural analyses using a synchrotron beam, such anomalous structural changes were revealed to originate from charge redistribution at nearby Ti4+ ions. Finally, the capacity was markedly enhanced, especially at high C-rates (125 mA h g-1 for 10C charge/10C discharge, 145 mA h g-1 for 1C charge/50C discharge) because of both the band gap narrowing and the increased ionic diffusivity due to the decreased structural disorder, but was decreased instead for too-high doping levels. © The Royal Society of Chemistry 2013.

Kim Y.-T.,Pusan National University | Lee H.,Yonsei University | Kim H.-J.,Korea Institute of Science and Technology | Lim T.-H.,Korea Institute of Science and Technology
Chemical Communications | Year: 2010

Core-shell PtRu clusters resembling dandelions were formed on thiolated carbon nanotubes by the difference in bond strength with surface thiol groups between Pt and Ru single atoms. The formation mechanism was clearly understood using a different release timing concept based on EXAFS and XPS analyses during heat treatment. © The Royal Society of Chemistry.