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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.

Nah K.-S.,Pusan National University
Imaging Science in Dentistry | Year: 2012

Purpose: Diagnosis of osteoarthritis most commonly depends on clinical and radiographic findings. The present study attempted to observe the bony changes in temporomandibular joint (TMJ) patients from all age groups. Materials and Methods: The first-visit clinical records and cone beam computed tomography (CBCT) data of 440 TMJs from 220 consecutive TMJ patients were reviewed retrospectively. Results: The most frequent condylar bony change observed was sclerosis (133 joints, 30.2%) followed by surface erosion (129 joints, 29.3%), flattening of the articular surface (112 joints, 25.5%), and deviation in form (58 joints, 13.2%), which included 33 TMJs in a cane-shape, 16 with a lateral or medial pole depression, 6 with posterior condylar surface flattening, and 3 with a bifid-shaped condyle. Fifty-three joints (12.0%) showed hypoplastic condyles but only 1 joint showed hyperplasia. Osteophyte was found in 35 joints (8.0%) and subcortical cyst in 24 joints (5.5%), 5 of which had surface erosion as well. One hundred nineteen joints (27.0%) had only one kind of condylar bony change, 66 joints (15.0%) had two, 52 joints (11.8%) had three, 12 joints (5.0%) had four, and 6 joints (1.4%) had five kinds of condylar bony changes at the same time. Eighty-five (65.9%) of 129 joints with surface erosion had pain recorded at the chief complaint. Conclusion: With more widespread use of CBCT, more specific or detailed guidelines for osteoarthritis are needed. © 2012 by Korean Academy of Oral and Maxillofacial Radiology.

Ahn J.S.,Pusan National University
Superlattices and Microstructures | Year: 2014

A finite difference method (FDM) applicable to a two dimensional (2D) quantum dot was developed as a non-conventional approach to the theoretical understandings of quantum devices. This method can be applied to a realistic potential with an arbitrary shape. Using this method, the Hamiltonian in a tri-diagonal matrix could be obtained from any 2D potential, and the Hamiltonian could be diagonalized numerically for the eigenvalues. The legitimacy of this method was first checked by comparing the results with a finite round well with the analytic solutions. Two truncated harmonic wells were examined as a realistic model potential for lateral double quantum dots (DQDs) and for triple quantum dots (TQDs). The successful applications of the 2D FDM were observed with the entanglements in the DQDs. The level-splitting and anticrossing behaviors of the DQDs could be obtained by varying the distance between the dots and by introducing asymmetry in the well-depths. The 2D FDM results for linear/triangular TQDs were compared with the tight binding approximations. © 2013 Elsevier Ltd. All rights reserved.

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.

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.

Chung T.,Pusan National University
Journal of Plant Biology | Year: 2011

Eukaryotic cells have two conserved pathways for degrading polypeptides. One is the highly selective ubiquitin-proteasome system, and the other is autophagy, a bulk degradation pathway to a lytic compartment. Autophagy in plant cells has important roles in development and responses to abiotic and biotic stresses. Furthermore, plant autophagy has been implicated in vacuole biogenesis and Golgi-independent targeting of cytoplasmic materials to vacuoles. Here I present four questions that are frequently asked by plant scientists interested in autophagy. The first question relating to tools for plant autophagy research is relatively easy to answer, while the others are open questions about regulation of autophagy, autophagic cargoes, and potential differences of plant autophagic routes from corresponding metazoan pathways. This review will discuss recent progress that may provide the answers for the latter questions. © 2011 The Botanical Society of Korea.

Kumar P.,Maharishi Markandeshwar University | Shim Y.-B.,Pusan National University
Journal of Electroanalytical Chemistry | Year: 2011

A novel poly(vinyl chloride) based membrane containing 5,10,15,20- tetrakis(2-furyl)-21,23-dithiaporphyrin (I) as an electroactive material along with sodiumtetraphenylborate (NaTPB), and nitrophenyl octyl ether (NPOE) in the ratio 10:100:1:150 (I:NPOE:NaTPB:PVC) (w/w) was used to fabricate a Mg(II)-selective sensor. The developed sensor exhibits a wide working concentration range of 9.2 × 10-6-1.0 × 10-1 M, with a Nernstian slope of 30.0 ± 1.0 mV/decade of activity and the response time of 15 s. This sensor shows a detection limit of 8.0 × 10-6 M. Its potential response remains unaffected of pH in the range 4.0-8.4, and the cell assembly can be successfully used in partially non-aqueous medium (up to 10% v/v) without any significant change in the slope or working concentration range. The sensor has a lifetime of about 8 weeks and exhibits excellent selectivity over a number of mono-, bi-, and tri-valent cations including alkali, alkaline earth metal, heavy and transition metal ions. It has also been used for the determination of magnesium ion concentration in real samples. © 2011 Elsevier B.V. All rights reserved.

Kim J.K.,LG Corp | Jeong J.H.,Pusan National University
International Journal of Refrigeration | Year: 2013

A linear compressor requires stroke controllers, as the piston movement is sensitive to the ambient temperature. This paper presents the performance characteristics of an inherent capacity-modulated (ICM) linear compressor. The compressor is capable of modulating its capacity independently without requiring stroke controllers. Electric parameters are designed to deliver inherent capacity modulation in accordance with variations in the cooling demand. An inherent capacity modulation method according to cooling demand levels was proposed and a prototype compressor was constructed. Its performance was evaluated with the cooling capacity ratio varying from 50 to 100% at an evaporating temperature of -26°C and a condensing temperature of 38°C. The total efficiency of the ICM linear compressor was as high as that of an electrical resonant system. This shows that the COP difference between the ICM linear compressor and the linear compressor controlled by an electrical resonance system appeared to be less than 1% over a wide cooling capacity ratio range of 50-100%. The results for the conventional linear compressor did not account for the power consumed by the electronic drive, so thus the ICM linear compressor had the potential improvement for energy saving. © 2012 Elsevier Ltd and IIR. All rights reserved.

Kim H.,Korea Institute of Industrial Technology | Kim D.,Korea Institute of Industrial Technology | Kim C.,Korea Institute of Industrial Technology | Jeong H.,Pusan National University
CIRP Annals - Manufacturing Technology | Year: 2013

This study examined the multi-wire sawing of C-plane sapphire ingots using diamond wires. Feeding new wire during the reciprocating motion of the wire was found to vary the cutting force, wafer shape, and roughness as a result of the break-in effect. The break-in and wire wear seemed to cause a gradual change in the cutting performance along the ingot position. The cutting force results indicated that an inappropriate supply of wire yielded an unbalanced force between the front and back sides of the ingot, which was caused by a difference in the cutting depth along the ingot. The results showed that controlling the wire consumption resulted in an average flatness of 16 μm, with a maximum value of 26 μm. © 2013 CIRP.

Carbotte J.P.,McMaster University | Timusk T.,McMaster University | Hwang J.,Pusan National University
Reports on Progress in Physics | Year: 2011

We review a number of experimental techniques that are beginning to reveal fine details of the bosonic spectrum α2F(Ω) that dominates the interaction between the quasiparticles in high-temperature superconductors. Angle-resolved photoemission spectroscopy (ARPES) shows kinks in electronic dispersion curves at characteristic energies that agree with similar structures in the optical conductivity and tunnelling spectra. Each technique has its advantages. ARPES is momentum resolved and offers independent measurements of the real and imaginary part of the contribution of the bosons to the self-energy of the quasiparticles. The optical conductivity can be used on a larger variety of materials and with the use of maximum entropy techniques reveals rich details of the spectra including their evolution with temperature and doping. Scanning tunnelling spectroscopy offers spatial resolution on the unit cell level. We find that together the various spectroscopies, including recent Raman results, are pointing to a unified picture of a broad spectrum of bosonic excitations at high temperatures which evolves, as the temperature is lowered, into a peak in the 30-60 meV region and a featureless high-frequency background in most of the materials studied. This behaviour is consistent with the spectrum of spin fluctuations as measured by magnetic neutron scattering. However, there is evidence for a phonon contribution to the bosonic spectrum as well. © 2011 IOP Publishing Ltd.

Kim T.K.,Pusan National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2013

Tuberculous liver abscesses are rare. Paradoxical response in tuberculosis is common and occurred between 2 weeks and 12 weeks after anti-tuberculous medication. We report here a case of tuberculous liver abscess that developed in a paradoxical response during chemotherapy for tuberculous peritonitis in a 23-year-old male. He was hospitalized, complaining of ascites, epigastric pain. He was diagnosed tuberculous peritonitis by expiratory laparoscopic biopsy and took medication for tuberculosis. After 2 months, a hepatic lesion was detected with CT scan incidentally. Chronic granulomatous inflammation was seen in ultrasound-guided liver biopsy, and tuberculous liver abscess was diagnosed. It was considered as paradoxical response, rather than treatment failure or other else because clinical symptoms of peritoneal tuberculosis and CT scan improved. After continuing initial anti-tuberculous medication, he was successfully treated. Herein, we report a case of tuberculous liver abscess as paradoxical response while treating peritoneal tuberculosis without changing anti-tuberculous treatment regimen.

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.

Mohammadzadeh S.,Worcester Polytechnic Institute | Kim Y.,Worcester Polytechnic Institute | Ahn J.,Pusan National University
Smart Structures and Systems | Year: 2015

This paper proposes an efficient system identification method for modeling nonlinear behavior of civil structures. This method is developed by integrating three different methodologies: principal component analysis (PCA), artificial neural networks, and fuzzy logic theory, hence named PANFIS (PCA-based adaptive neuro-fuzzy inference system). To evaluate this model, a 3-story building equipped with a magnetorheological (MR) damper subjected to a variety of earthquakes is investigated. To train the input-output function of the PANFIS model, an artificial earthquake is generated that contains a variety of characteristics of recorded earthquakes. The trained model is also validated using the1940 El-Centro, Kobe, Northridge, and Hachinohe earthquakes. The adaptive neuro-fuzzy inference system (ANFIS) is used as a baseline. It is demonstrated from the training and validation processes that the proposed PANFIS model is effective in modeling complex behavior of the smart building. It is also shown that the proposed PANFIS produces similar performance with the benchmark ANFIS model with significant reduction of computational loads. Copyright © 2015 Techno-Press, Ltd.

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..

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.

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.

Kim K.C.,Pusan National University
Journal of Mechanical Science and Technology | Year: 2012

Reliable measurements of the three-dimensional, three-component (3D3C) velocity field in microfluidics are becoming increasingly important for the design and optimization of lab-on-a-chip devices in biochemical applications. Among the many microscale 3D3C ve-locity field measurement methods, the μ-DDPIV technique is the most convenient and reliable, but the low seeding rates and low light intensity due to the small pinholes are the major limitations of this technique. The present review demonstrates the principle of the defo-cusing technique, calibration procedures and particle tracking algorithms to extract the 3D3C velocity vectors. As an example of μ-DDPIV applications, this paper presents measurements of a complex 3D3C velocity field in chaotic mixers. This technique can be ex-tended to measure the refractive index of an unknown fluid and to a nano/micro hybrid PIV system for multi-scale measurements. Future perspectives on the development of μ-DDPIV are addressed. © KSME & Springer 2012.

Jeong Y.,Pusan National University
Electronics Letters | Year: 2013

The application of probabilistic linear discriminant analysis (PLDA) to speaker adaptation for automatic speech recognition based on hidden Markov models is proposed. By expressing the set of acoustic models of each of the training speakers in a matrix and treating each column as a sample, the small sample problem that can be encountered in PLDA if only one sample is available for each training speaker is overcome. In the continuous speech recognition experiments, the performance of the PLDA based approach improves over the principal component analysis (PCA) based approach and the two-dimensional PCA based approach for adaptation data longer than 12 s. © The Institution of Engineering and Technology 2013.

Lee K.-S.,Pusan National University
Reproductive biology and endocrinology : RB&E | Year: 2014

BACKGROUND: Many studies have proposed that putative ovarian stem cells (OSCs) derived from the ovarian surface epithelium (OSE) layer of adult mammalian ovaries can produce oocytes. Few studies have reported that ovaries of aged mammalian females including mice and women possess rare premeiotic germ cells that can generate oocytes. However, no studies have reported the changes of OSCs according to the age of the female. Therefore, this study evaluated pluripotent and germ cell marker expression in the intact ovary, scraped OSE, and postcultured OSE according to age in female mice.METHODS: C57BL/6 female mice of 2 age groups (6-8 and 28-31 weeks) were superovulated by injection with 5 IU equine chorionic gonadotropin (eCG). Both ovaries were removed after 48 hours and scrapped to obtain OSE. Gene expressions of pluripotent (Oct-4, Sox-2, Nanog) and germ cell markers (c-Kit, GDF-9, and VASA) were evaluated by RT-PCR. VASA and GDF-9 were immune-localized in oocyte-like structures.RESULTS: Expressions of germ cell markers in the intact ovary were significantly decreased in aged females, whereas expressions of pluripotent markers were not detected, regardless of age. Scraped OSE expression of all pluripotent and germ cell markers, except for c-Kit, was similar between both age groups. Three weeks postcultured OSE had significantly decreased expression of GDF-9 and VASA , but not c-Kit, in old mice, as compared to young mice; however there was no difference in the expression of other genes. The number of positively stained Oct-4 by immunohistochemistry in postcultured OSE was 2.5 times higher in young mice than aged mice. Oocyte-like structure was spontaneously produced in postcultured OSE. However, while that of young mice revealed a prominent nucleus, zona pellucida-like structure and cytoplasmic organelles, these features were not observed in old mice.CONCLUSIONS: These results show that aged female mice have putative OSCs in OSE, but their differentiation potential, as well as the number of OSCs differs from those of young mice.

Kwon S.,Georgia Institute of Technology | Choi J.I.,Korea Advanced Institute of Science and Technology | Lee S.G.,Pusan National University | Jang S.S.,Georgia Institute of Technology
Computational Materials Science | Year: 2014

In this study, we investigated the adsorption of multiple CO2 on Mg-rich minerals such as magnesium oxide (MgO) and olivine (MgSi 2O4) surface in order to understand the adsorption mechanism of CO2 using density functional theory (DFT) approach. It is found that the energy required for the adsorption of CO2 onto Mg2SiO4 surface is 2.5 times (-1.30 eV) and 2.7 times (-0.70 eV) higher than that onto MgO surface for single and multiple CO 2 chemisorption, respectively. The surface coverage (θ) of Mg2SiO4 surface is 1, which is four times higher than that of MgO surface. By analyzing the charge distribution of each atom of the MgO and Mg2SiO4 surfaces before and after the adsorption of CO2 molecules, we observed that charge redistribution occurs more readily in CO2-Mg2SiO4 than in CO 2-MgO. © 2014 Elsevier B.V. All rights reserved.

Li F.,University of Wisconsin - Madison | Chung T.,University of Wisconsin - Madison | Chung T.,Pusan National University | Vierstra R.D.,University of Wisconsin - Madison
Plant Cell | Year: 2014

Autophagy-mediated turnover removes damaged organelles and unwanted cytoplasmic constituents and thus plays critical roles in cellular housekeeping and nutrient recycling. This "self eating" is tightly regulated by the AUTOPHAGY-RELATED1/13 (ATG1/13) kinase complex, which connects metabolic and environmental cues to the vacuolar delivery of autophagic vesicles. Here, we describe the Arabidopsis thaliana accessory proteins ATG11 and ATG101, which help link the ATG1/13 complex to autophagic membranes. ATG11 promotes vesicle delivery to the vacuole but is not essential for synthesizing the ATG12-ATG5 and ATG8-phosphatidylethanolamine adducts that are central to autophagic vesicle assembly. ATG11, ATG101, ATG1, and ATG13 colocalize with each other and with ATG8, with ATG1 tethered to ATG8 via a canonical ATG8-interacting motif. Also, the presence of ATG11 encourages starvation-induced phosphorylation of ATG1 and turnover of ATG1 and ATG13. Like other atg mutants, ATG11-deficient plants senesce prematurely and are hypersensitive to nitrogen and fixed-carbon limitations. Additionally, we discovered that the senescence-induced breakdown of mitochondria-resident proteins and mitochondrial vesicles occurs via an autophagic process requiring ATG11 and other ATG components. Together, our data indicate that ATG11 (and possibly ATG101) provides important scaffolds connecting the ATG1/13 complex to both general autophagy and selective mitophagy. © 2014 American Society of Plant Biologists. All rights reserved.

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.

Lim H.-C.,Pusan National University
Ocean Engineering | Year: 2014

We simulated coastal waves and wave absorbers in a lab-scale wave flume. The goal of this study was to observe and optimize a typical ocean environment and to reduce the wall reflection in the wave flume. In order to generate ocean waves in the wave flume, a combination of a flat-type wave generator and wave absorbers was installed in the channel. Two probes for measuring the wave heights, i.e., level gauges, were used to observe the temporal variation of the wave surface as well as the phase difference and maximum (crest) and minimum (trough) points between the propagating waves. In order to optimize the shape and size of the propagating waves, several absorption methods were proposed. Apart from an active wave absorption method, we used methods that involved vertical, porous plates; horizontal, punching plates; and sloping-wall-type wave absorbers. For obtaining the best propagating waves, the sloping-wall-type wave absorbers were chosen and tested in terms of the constitutive filling materials and the location and shape of the plate. This study also focused on the theoretical prediction of the wave surface, separating them into incident and reflective components. From the results, it is evident that the wave absorber comprised a hard filling material exhibits a better performance than the absorber comprised soft material; i.e., the wave absorber can be a strong sink to control the energy of the oncoming wave. In addition, larger wave absorbers corresponded to lower reflectance because the larger volume can remove the oncoming wave energy better. Therefore, with constant absorber conditions, the reflectance increases as the wave period increases. Finally, the reflectance of the wave was controlled to be less than 0.1 in this study so that the wave flume could be applied to simulate the offshore environment. © 2014 Elsevier Ltd.

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.

Cho H.,Pusan National University | Yun Y.-H.,Dongshin University
Ceramics International | Year: 2011

Indium tin oxide (ITO) thin films were prepared by a sol-gel spin coating method, fired, and then annealed in the temperature range of 450-600°. The XRD patterns of the thin films indicated the main peak of the (2 2 2) plane and showed a higher degree of crystallinity with an increase in the annealing temperature. Upon annealing the films at 500 and 600°, two binding energy levels of Sn4+ ion of 486.9 eV and 486.6 eV, respectively, were measured in the XPS spectra. The ITO film that was annealed at 600° contained two oxidation states of Sn, Sn2+ and Sn4+, and it had a higher sheet resistance based on a rather low doping concentration of Sn4+. The film that was annealed at 500° and subsequently treated with 0.1 N HCl solution for 40 s showed a sheet resistance of 225 Ω/square. The surface treatment by the acidic solution diminished the RMS (root mean square) roughness value and the residual carbon content (XPS peak intensity of carbon) of the ITO films. It seems that the acid-cleaning of the ITO thin films led to a decrease of the surface roughness and sheet resistance. © 2010 Elsevier Ltd and Techna Group S.r.l.

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.

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.

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.

Ann H.B.,Pusan National University
Journal of the Korean Astronomical Society | Year: 2014

We analyze the dependence of disk morphology (arm class, Hubble type, bar type) of nearby spiral galaxies on the galaxy environment by using local background density (∑n), projected distance (rp), and tidal index (T I) as measures of the environment. There is a strong dependence of arm class and Hubble type on the galaxy environment, while the bar type exhibits a weak dependence with a high frequency of SB galaxies in high density regions. Grand design fractions and early-type fractions increase with increasing ∑n, 1/rp, and T I, while fractions of flocculent spirals and late-type spirals decrease. Multiple-arm and intermediate-type spirals exhibit nearly constant fractions with weak trends similar to grand design and early-type spirals. While bar types show only a marginal dependence on ∑n, they show a fairly clear dependence on rp with a high frequency of SB galaxies at small rp. The arm class also exhibits a stronger correlation with rp than ∑n and TI, whereas the Hubble type exhibits similar correlations with ∑n and rp. This suggests that the arm class is mostly affected by the nearest neighbor while the Hubble type is affected by the local densities contributed by neighboring galaxies as well as the nearest neighbor. © 2014 The Korean Astronomical Society. All Rights Reserved.

Choi K.-Y.,Korea Astronomy and Space Science Institute | Kyae B.,Pusan National University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

BICEP2 has observed a primordial gravitational wave corresponding to the tensor-to-scalar ratio of 0.16. It seems to require a super-Planckian inflationary model. In this paper, we propose a double hybrid inflation model, where the inflaton potential dynamically changes with the evolution of the inflaton fields. During the first phase of inflation over 7 e-folds, the power spectrum can be almost constant by a large linear term in the hybrid potential, which is responsible also for the large tensor-to-scalar ratio. In the second phase of 50 e-folds, the dominant potential becomes dynamically changed to the logarithmic form as in the ordinary supersymmetric hybrid inflation, which is performed by the second inflaton field. In this model, the sub-Planckian field values (̃0.9M P) can still yield the correct cosmic observations with the sufficient e-folds. © 2014 Elsevier B.V.

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.

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.

Sohn E.J.,Pusan National University
Cellular and molecular biology (Noisy-le-Grand, France) | Year: 2012

TGF-β is a mediator of lung fibrosis and regulates the alveolar epithelial type II cell phenotype. TGF-β can induce epithelial mesenchymal transition of idiopathic pulmonary disease and cancer metastasis. Peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC-1 α) is a key metabolic regulator that stimulates mitochondrial biogenesis and promotes remodeling of muscle tissue to oxidative fiber-type composition. Here, we report that the induction of TGF-β decreased mRNA expression of PGC-1α, and PGC-1 target genes, such as the transcription factors NRF-2, ERR-α, and PPAR-γ in lung epithelial A549 cells. In addition, TGF-β led to the reduction of super oxide dismutase 2 (anti-oxidant enzyme), cytochrome C (electron transport chain in mitochondria), and MCAD (a mitochondrial β-oxidant enzyme) in A549 cells. Together, our results suggest that TGF-β may suppress the transcriptional activity of the genes related to mitochondrial biogenesis or function. This mechanism may provide a novel insight into the understanding of fibrosis disease.

Parent B.,Pusan National University
Journal of Computational Physics | Year: 2013

A positivity-preserving variant of the Roe flux difference splitting method is here proposed. Positivity-preservation is attained by modifying the Roe scheme such that the coefficients of the discretization equation become positive, with a coefficient considered positive if all its eigenvalues are positive and if its eigenvectors correspond to those of the flux Jacobian. Because the modification does not alter the wave speeds at the interface, the appealing attributes of the Roe flux difference splitting schemes are retained, such as high-resolution capture of discontinuous waves, low amount of artificial dissipation within viscous layers, and ease of convergence to steady-state. The proposed flux function is advantaged over previous positivity-preserving variants of the Roe method by being written in general matrix form and hence by being readily deployable to arbitrary systems of conservation laws. The stencils are extended to second-order accuracy through a newly-derived positivity-preserving total-variation-diminishing limiting process that is applied to the characteristic variables and that yields positive coefficients. Also derived is a positivity-preserving restriction on the time step for flux difference splitting schemes that is shown to depart significantly from the CFL condition in regions with high property gradients. © 2013 Elsevier Inc.

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.

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.

Objective: Unusual setting of medical care Background: As the incidence of meningeal carcinomatosis (MC) in non-small cell lung cancer (NSCLC) patients has been increasing, MC has recently become an important clinical problem in the management of NSCLC. However, development of new treatments is lacking and a standard treatment guideline is not yet available. Research on salvage intrathecal chemotherapy after failure of first-line treatment for NSCLC patients with MC has rarely been reported in the literature. Here, we report the case of an NSCLC patient with MC who showed durable response to salvage intrathecal etoposide subsequent to failure of first-line methotrexate. Case Report: A 58-year-old Asian man with lung adenocarcinoma with bone metastasis presented gait disturbance, diplopia, and progressively increasing headache. The diagnosis of MC was made by brain magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) cytology. After MC progression was suspected during the first-line treatment of intrathecal MTx, intrathecal etoposide was used as a salvage treatment. Brain MRI performed after 2 months of the treatment demonstrated disappearance of enhancing lesions along the ependymal lining of the lateral ventricles. His clinical status markedly improved from Eastern Cooperative Oncology Group performance status of 4 to 2. Stable neurologic status was maintained and CSF cytology remained negative while weekly injection of etoposide was continued for 19 weeks. However, hepatic metastatic lesions persistently progressed despite systemic palliative chemotherapy and the patient died of the disease. Conclusions: To our knowledge, this is the first case report in which intrathecal etoposide was successfully used to treat MC from NSCLC after failure of MTx. This case report might provide preliminary evidence of the feasibility of intrathecal etoposide as salvage intrathecal chemotherapy (ITC). Further clinical trials including larger numbers of patients are necessary to evaluate the role of this ITC regimen for NSCLC patients with MC. © Am J Case Rep, 2015.

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.

Kang S.,Pusan National University | Hur W.-M.,Yonsei University
Corporate Social Responsibility and Environmental Management | Year: 2012

This study proposed five novel constructs - green satisfaction, green affect, green trust, green brand loyalty, and green brand equity - and explored the positive relationships between these constructs. Electronics products in South Korea were the focus of this research. This empirical study was carried out by the one-to-one interview method using a structured questionnaire. The results showed that green brand satisfaction has a positive effect on green trust, affect, and loyalty. In addition, the results revealed that green brand, trust, and affect have a significantly positive influence on green brand loyalty. Furthermore, we found that green brand loyalty has a strongly positive influence on green brand equity. This study suggests that in addition to the perceived green trust arising from eco-friendly attributes, green affect characterized by positive emotional consumption plays an important role in building green loyalty and green brand equity for sustainable development. © 2011 John Wiley & Sons, Ltd and ERP Environment.

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.

Kim S.,Pusan National University
Annales de Limnologie | Year: 2016

The concentration of chlorophyll-a (Chl-a) in river systems is dependent on various hydrometric and biochemical factors, including an intricate array of corresponding growth and extinction mechanisms. This complex and interactive assortment of factors makes prediction of algal blooms difficult. This paper introduces an innovative time-series model structure that predicts Chl-a concentration in inland waters. To improve the prediction accuracy of existing models, we assume that the predicting variable is determined by multiple and independent drivers. An enhanced stochastic model, namely a multiple process univariate model (MPUM), is developed to address the impacts of the distinct mechanisms associated with each regulator (e.g., hydrometeorological factors and anthropogenic activities). Observations of the algae concentration at 16 weirs along four major river systems in South Korea are used to model Chl-a concentration. Comparisons between traditional models and the proposed method demonstrate the strengths of the MPUM, both in making predictions and in the parsimony of the model structure. The robustness of the developed model was further validated by modeling algae concentration before and after river-flow regulation procedures. © 2016 EDP Sciences.

Han S.,Chonbuk National University | Yoon Y.Y.,Chonbuk National University | Jung O.-S.,Pusan National University | Lee Y.-A.,Chonbuk National University
Chemical Communications | Year: 2011

Reversible interconversion between inter- and intramolecular Au⋯Au interactions induces luminescence on/off switching in solid state. For the gold(i) photoluminescence system, intermolecular aurophilic interaction is a more significant factor than intramolecular aurophilic interaction. © 2011 The Royal Society of Chemistry.

Jeong Y.,Pusan National University
Journal of Signal Processing Systems | Year: 2016

This paper presents the basis-based speaker adaptation method that includes approaches using principal component analysis (PCA) and two-dimensional PCA (2DPCA). The proposed method partitions the hidden Markov model (HMM) mean vectors of training models into subvectors of smaller dimension. Consequently, the sample covariance matrix computed using the partitioned HMM mean vectors has various dimensions according to the dimension of the subvectors. From the eigen-decomposition of the sample covariance matrix, basis vectors are constructed. Thus, the dimension of basis vectors varies according to the dimension of the sample covariance matrix, and the proposed method includes PCA and 2DPCA-based approaches. We present the adaptation equation in both the maximum likelihood (ML) and maximum a posteriori (MAP) frameworks. We perform continuous speech recognition experiments using the Wall Street Journal (WSJ) corpus. The results show that the model with basis vectors whose dimensions are between those of PCA and 2DPCA-based approaches shows good overall performance. The proposed approach in the MAP framework shows additional performance improvement over the ML counterpart when the number of adaptation parameters is large but the amount of available adaptation data is small. Furthermore, the performance of the approach in the MAP framework approach is less sensitive to the choice of model order than the ML counterpart. © 2015, Springer Science+Business Media New York.

Kim H.S.,Pusan National University | Kim W.J.,Hongik University
Corrosion Science | Year: 2013

Ultrafine-grained (1.1-1.5μm) AZ61 alloys containing nanoscaled β-Mg17Al12 phase particles (70-140nm) were prepared using high-ratio differential speed rolling (HRDSR) and their corrosion behaviours were studied in a 0.1M NaCl solution. The grain size reduction by HRDSR improved the corrosion resistance by enhancing passivity of the surface film. Post-annealing further increased the corrosion resistance by decreasing dislocation density in matrix. When significant grain growth took place, however, the corrosion resistance was decreased because of the pronounced negative effect of the increase in grain size. Refinement of β phase to nanoscale size decreased the susceptibility to microgalvanic corrosion. © 2013 Elsevier Ltd.

Lee D.,Sejong University | Shin S.,Pusan National University
Engineering Structures | Year: 2015

This research relates to a reinforced version of existing column structures based on reinforcing plates. More specifically, this research aims to propose a new type of reinforced column structure based on reinforcing plates that has stronger resistance against the load of architectural structures. The reinforced structure of column structures based on reinforced plates supports reinforcing plates, which are combined to form a closed section through attachment to the outer circumference surface of the column structures; reinforcing members containing other reinforcing plates, which are combined to form a closed section around the other circumference surface of the reinforcing plates; joint members which combine the reinforcing members on the outer circumference surface of the column structure, and the load of a beam member at the contact part of the column structure and of a beam member equipped between the beam member and the reinforcing members. Furthermore, the reinforced structure is also composed of plate members with the shape of a variable cross-section, whose thickness increases as it gets closer to the column structure. Through a non-linear structural-behavior analytical test based on FEM-ABAQUS 6.5-1, the structural stiffness and ductility of new reinforcement-method alternatives of RC column structures based on reinforcing steel plates was investigated, and the result values for parameters of steel material characteristics were comparatively verified. © 2015 Elsevier Ltd.

A new nonlinear inverse method of nonparametric identification is proposed for both recovering the full nonlinear damping and restoring functions in a harmonic forced nonlinear oscillator. For that, a proper inverse problem and its mathematical formalism are developed by introducing the intersection and zero-crossing times with respect to motion response, based on the acceleration response measurements. We have found that the present inverse study is well-posed in the sense of stability, i.e., it has stability properties. This implies that the identification does not depend on the usual regularisations, which, however, is generally essential to the usual (ill-posed) inverse problems arising in mathematical science and engineering. As a model equation, a highly nonlinear system is examined for the workability of the inverse method proposed here through numerical experiments. © 2014 Taylor & Francis.

Jeong S.-Y.,Korea Institute of Energy Research | Yoon S.-H.,Pusan National University
Building and Environment | Year: 2012

This study aims to provide basic data for green building projects with respect to the thermal environment of the architecture-urban level scale in combination with outdoor thermal environment problems and the heat island phenomenon using numerical simulation. The study models were selected typical flat and tower apartment residential housing in Korea; 54 cases were defined using an orthogonal array table based on experimental design. These cases are analyzed to quantify the outdoor thermal comfort (mean radiation temperature distribution) and heat island potential (HIP) change throughout a day according to several design variables (building type, site planning type, façade direction, and landscape ratio). A three-dimensional numerical simulation of all surface temperatures is performed. The results are analyzed statistically using multivariate analysis of variance. It was quantitatively characterize the effects of the design parameters on the outdoor thermal environment of the apartment housing. An evaluation index of the design parameters is proposed. A designer can apply the proposed index in the design process and in feedback for green apartment housing projects. © 2012 Elsevier Ltd.

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.

Kim S.,Pusan National University | Jung S.,Hydrologic Survey Center
Hydrological Processes | Year: 2014

A method for estimating daily mean transit time (DMTT) within a soil layer was proposed using field measurements of soil moisture. Vertical profiles of soil moisture time series were used for storage estimation. Water fluxes were evaluated through matrix and bypass flow. Variations in soil moisture and soil thickness were used to evaluate matrix flow. Exponential decay in depth of macropores was also used for bypass flow approximation. DMTT evaluation was compared to results obtained from a stable water isotope model using two years of data acquired on a steep granite hillslope in the Sulmachun watershed, South Korea. Various uncertainties in transit time evaluation such as model structure, non-stationary assumption and data acquisition of existing approaches can be accounted for in the proposed methodology, and the flowpath contribution can be further configured in conjunction with hydrometric measurements. Probability density functions of isotope analyses were partially explained by transit time distributions that were based on soil moisture measurements. Supplementary sensitivity analyses for uncertainty configurations indicate that matrix flow is the primary process in determining transit time distribution while the impact of bypass flow is minor. The feasibility of a DMTT approach over isotope-based methodologies highlights not only the strength of this proposed method, both in cost and time, but also its further application potential for existing soil moisture measurements. © 2013 John Wiley & Sons, Ltd.

Singh R.P.,Pusan National University | Singh R.P.,Allahabad University
Analyst | Year: 2011

Tyrosinase has been immobilized on a Au nanoparticles encapsulated- dendrimer bonded conducting polymer on a glassy carbon electrode for the estimation of catechol. The modified electrode was characterized by cyclic voltammetry and AFM techniques. The principle of catechol estimation was based on the reduction of biocatalytically liberated quinone species at +0.2 V versus Ag/AgCl (3 M KCl), with good stability, sensitivity, and featuring a low detection limit (about 0.002 μM) and wide linear range (0.005 μM-120 μM). The electrochemical redox peak of catechol on the GCE/PolyPATT/ Den(AuNPs)/tyrosinase was also investigated. A response time of 7 s, reusability up to 5 cycles and a shelf life of more than 2 months under refrigerated conditions were reported. Various parameters influencing biosensor performance have been optimized including pH, temperature, and applied potential. The utility and application of this nanobiosensor was tested in a real water samples. © 2011 The Royal Society of Chemistry.

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.

Yoo S.Y.,Pusan National University
Mediators of inflammation | Year: 2013

Angiogenesis plays critical roles in human physiology that range from reproduction and fetal growth to wound healing and tissue repair. The sophisticated multistep process is tightly regulated in a spatial and temporal manner by "on-off switch signals" between angiogenic factors, extracellular matrix components, and endothelial cells. Uncontrolled angiogenesis may lead to several angiogenic disorders, including vascular insufficiency (myocardial or critical limb ischemia) and vascular overgrowth (hemangiomas, vascularized tumors, and retinopathies). Thus, numerous therapeutic opportunities can be envisaged through the successful understanding and subsequent manipulation of angiogenesis. Here, we review the clinical implications of angiogenesis and discuss pro- and antiangiogenic agents that offer potential therapy for cancer and other angiogenic diseases.

Cerenius L.,Uppsala University | Kawabata S.-I.,Kyushu University | Lee B.L.,Pusan National University | Nonaka M.,University of Tokyo | Soderhall K.,Uppsala University
Trends in Biochemical Sciences | Year: 2010

Bacteria and other potential pathogens are cleared rapidly from the body fluids of invertebrates by the immediate response of the innate immune system. Proteolytic cascades, following their initiation by pattern recognition proteins, control several such reactions, notably coagulation, melanisation, activation of the Toll receptor and complement-like reactions. However, there is considerable variation among invertebrates and these cascades, although widespread, are not present in all phyla. In recent years, significant progress has been made in identifying and characterizing these cascades in insects. Notably, recent work has identified several connections and shared principles among the different pathways, suggesting that cross-talk between them may be common. © 2010 Elsevier Ltd.

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.

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.

Kim H.S.,Pusan National University | Kim W.J.,Hongik University
Corrosion Science | Year: 2014

The effect of annealing on the corrosion behaviour of the ultrafine-grained pure titanium (Ti) produced by high-ratio differential speed rolling was examined in a 0.5M H2SO4 solution using potentiodynamic polarisation and weight loss methods. The results indicated that post-rolling annealing significantly affected the corrosion resistance of ultrafine-grained Ti. It was concluded that annealing treatments leading to a decrease in dislocation density and residual stress while maintaining an ultrafine grain size and strong basal texture can allow for the development of pure Ti with a good combination of high strength and high corrosion resistance. © 2014 Elsevier Ltd.

Lee S.H.,Pusan National University
Cell structure and function | Year: 2011

Recent studies have suggested the involvement of epigenetic factors such as methyl-CpG-binding protein-2 (MeCP2) in tumorigenesis. In addition, cancer may represent a stem cell-based disease, suggesting that understanding of stem cell regulation could provide valuable insights into the mechanisms of tumorigenesis. However, the function of epigenetic factors in stem cell regulation in adult tissues remains poorly understood. In the present study, we investigated the role of human MeCP2 (hMeCP2), a bridge factor linked to DNA modification and histone modification, in stem cell proliferation using adult Drosophila midgut, which appears to be an excellent model system to study stem cell biology. Results show that enterocyte (EC)-specific expression of hMeCP2 in adult midgut using an exogenous GAL4/UAS expression system induced intestinal stem cell (ISC) proliferation marked by staining with anti-phospho-histone H3 antibody and BrdU incorporation assays. In addition, hMeCP2 expression in ECs activated extracellular stress-response kinase signals in ISCs. Furthermore, expression of hMeCP2 modulated the distribution of heterochromatin protein-1 in ECs. Our data suggests the hypothesis that the expression of hMeCP2 in differentiated ECs stimulates ISC proliferation, implying a role of MeCP2 as a stem cell regulator.

Lee J.E.,Pusan National University
Drying Technology | Year: 2014

Real-scale thermal filter press dewatering equipment (plate size: 630 mm × 630 mm) was installed and operated at a waterworks for one year in an attempt to achieve sludge reduction. During the period, the dewaterability was evaluated according to the seasonal sludge properties in order to compare the dewaterability of thermal dewatering and mechanical dewatering, as well as to determine the economics of thermal dewatering. According to the results, the winter season sludge showed a 36% decrease in water content and a two-thirds reduction in dewatering velocity compared to the summertime sludge. In addition, the dewatered cakes of the thermal filter press dewatering equipment showed a lower specific cake resistance and water content in the dewatered cakes than the mechanical filter press dewatering equipment, indicating superior dewaterability. This was attributed to the easier removal of the filtrate remaining in the capillary tubes due to thermal dewatering. The energy consumption for thermal dewatering was 300 kJ/dry solids (DS) kg. A comparison of the sludge dryers indicated that it is possible to produce dewatered cakes that consume less energy and can be recycled. According to the performance evaluation results, the real-scale thermal filter press dewatering equipment had high adaptability to the changes in seasonal sludge, showing excellent dewaterability compared to the mechanical filter press dewatering equipment, and was economical due to the lower energy consumption. © 2014 Copyright Taylor and Francis Group, LLC.

Chon T.-S.,Pusan National University
Ecological Informatics | Year: 2011

Ecological data are considered to be difficult to analyze because numerous biological and environmental factors are involved in a complex manner in environment-organism relationships. The Self-Organizing Map (SOM) has advantages for information extraction (i.e., without prior knowledge) and the efficiency of presentation (i.e., visualization). It has been implemented broadly in ecological sciences across different hierarchical levels of life. Recent applications of the SOM, which are reviewed here, include the molecular, organism, population, community, and ecosystem scales. Further development of the SOM is discussed regarding network architecture, spatio-temporal patterning, and the presentation of model results in ecological sciences. © 2010 Elsevier B.V.

Kim S.,Pusan National University
Journal of Hydrology | Year: 2016

The response of soil moisture to rainfall events along hillslope transects is an important hydrologic process and a critical component of interactions between soil vegetation and the atmosphere. In this context, the research described in this article addresses the spatial distribution of soil moisture as a function of topography. In order to characterize the temporal variation in soil moisture on a steep mountainous hillside, a transfer function, including a model for noise, was introduced. Soil moisture time series with similar rainfall amounts, but different wetness gradients were measured in the spring and fall. Water flux near the soil moisture sensors was modeled and mathematical expressions were developed to provide a basis for input-output modeling of rainfall and soil moisture using hydrological processes such as infiltration, exfiltration and downslope lateral flow. The characteristics of soil moisture response can be expressed in terms of model structure. A seasonal comparison of models reveals differences in soil moisture response to rainfall, possibly associated with eco-hydrological process and evapotranspiration. Modeling results along the hillslope indicate that the spatial structure of the soil moisture response patterns mainly appears in deeper layers. Similarities between topographic attributes and stochastic model structures are spatially organized. The impact of temporal and spatial discretization scales on parameter expression is addressed in the context of modeling results that link rainfall events and soil moisture. © 2016 Elsevier B.V..

Kim N.M.,Pusan National University
Korean journal of ophthalmology : KJO | Year: 2010

To evaluate the effect of epiblepharon surgery on visual acuity and with-the-rule astigmatism in children compared to patients without surgical treatment. We undertook a retrospective case control study and reviewed the charts of 202 eyes treated with epiblepharon surgery and of 142 eyes without surgery. The surgical procedure for epiblepharon correction used rotating suture techniques. Data regarding age, best corrected visual acuity, and degree of astigmatism were recorded. Baseline and 1-, 3-, 6-, and 12-month postoperative data were collected. The chi-square test, Student's t-test and general linear model analysis for repeated measures were applied. The mean astigmatism in the surgical group decreased from 1.10 ± 1.02 diopter (D) preoperatively to 0.84 ± 1.05 D at 3 months after surgery (p < 0.05). However, there was no statistically significant difference compared to the non-surgical group during the first year. The general linear model analysis comparing the mean astigmatism between the two groups over time showed a significant group-time interaction (p < 0.05). Within the surgical group, the higher baseline astigmatic subgroup and the 5- to 8-year-old group demonstrated greater cylinder reduction over time. The change in mean visual acuity was not significant in either group. Significant astigmatic reduction was found after surgical correction in epiblepharon patients. Patients with higher baseline astigmatism exhibited greater astigmatic reduction after epiblepharon surgery. These results suggest that, in order to reduce astigmatism, an epiblepharon operation should be considered in patients with a high level of astigmatism.

Cho Y.,Pusan National University
Journal of Nondestructive Evaluation | Year: 2012

The utility of those waves propagating over a distance, called "guided waves," provides abundant technical advantages in a variety of nondestructive evaluation (NDE) applications. In recent years, the field has rapidly grown as one of the most noticeable subjects in the NDE community, from not only the academic but also the practical standpoint, representing promising technological transfer. A number of commercialized inspection units and techniques are already available on the market. However, the principle of guided waves physics, which is crucial for proper usage and subsequent data analysis of the equipments has not been fully elucidated for field NDE engineers, and has mainly been set out for the purpose of simplifying the operation scheme. A simplified operation manual is necessary to bolster the market, but is quite often not sufficient to conduct the mission adequately. Do NDE engineers no longer need to understand guided wave physics? The knowledge on guided wave physics and advanced softwares are battling against the challenging task to turn the technique from magic to a reliable engineering tool. In this sense, the guided wave NDE technique now requires us to establish a firmer physical foundation, whereby its sophisticated features are understood, to enrich utility and correct the improper usage of field data; meanwhile, the instrumentation is rapidly being upgraded with more advanced functions. In this paper, the importance of a physical understanding of the characteristics of guided wave NDE is firstly addressed. Guided wave models can enhance NDE performance and alleviate the likelihood of a false call. Scattering of surface waves by a two-dimensional corrosion pit at the surface of a homogenous, isotropic, linearly elastic half-space is theoretically investigated in Sect. "A Guided Wave Measurement Model for Scattering of Surface Waves by a Corrosion Pit Based on the Use of the Elastodynamic Reciprocity". In Sect. "Model-Based Visualization of Defects Using Tomography", guided wave tomographic imaging of plate-like structures is presented using a probabilistic algorithm. Section "The Model-Based Guided Wave Focusing Technique to Improve Sensitivity" shows that the guided wave focusing technique can be used to focus energy in both the circumferential and axial directions in pipes. The unique nonlinear features among different guided wave modes, which can be used to choose a proper mode with better sensitivity for micro-damage detection, are reported in Sect. "Model-Based Nonlinear Guided Wave Techniques for Micro-Damage Detection". © 2012 Springer Science+Business Media, LLC.

OBJECTIVES: Although prolonged intravenous infusion (24 hours) of nafamostat mesilate is effective for the prevention of post–endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis, it requires hospitalization and is expensive. The aim of this study was to compare the efficacy of 24- versus 6-hour intravenous infusion of 20 mg nafamostat mesilate for the prevention of post-ERCP pancreatitis (PEP). METHODS: A total of 382 patients who underwent ERCP were randomly assigned into 2 groups: 24 hours or 6 hours. In both groups, nafamostat mesilate (20 mg) infusion was initiated up to an hour before ERCP and continued for either 24 or 6 hours. RESULTS: The overall incidence of pancreatitis was 2.4% (9/371). The rates of PEP following 24- and 6-hour infusion were 2.8% (5/179) and 2.1% (4/192), respectively (P = 0.744). No significant difference was observed in the severity of pancreatitis between the groups. On multivariate analysis, increasing pancreatic duct cannulations (odds ratio, 1.685; 95% confidence interval, 1.036–2.741; P = 0.036) was identified as a statistically significant risk factor of PEP. CONCLUSIONS: No difference was found in the incidence of PEP regardless of the duration of nafamostat mesilate infusion. Therefore, 6-hour infusion of 20 mg nafamostat mesilate may be useful for the prevention of PEP in an outpatient setting. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

Okman O.,Columbia University | Lee D.,Pusan National University | Kysar J.W.,Columbia University
Scripta Materialia | Year: 2010

Nanoporous gold (NPG) is of interest due to its very high surface area to volume ratio. The fabrication of crack-free blanket NPG thin films on silicon substrates using standard clean room methods is reported. Ag-Au precursor alloys are deposited both by thermal vapor deposition as well as by sputter deposition. Dealloying is performed using two different electrochemical regimens, one with a stepped potential increase and the other with a ramped increase. The ramped increase gives better NPG film uniformity. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Lee N.C.,Pusan National University
Physics of Plasmas | Year: 2011

The existence of localized structure of electromagnetic waves in relativistic electron-positron plasmas is investigated based on the pseudo-potential theory, without making any assumptions on the magnitudes of the flow velocity and temperature of the medium. The conditions for the localization of electromagnetic wave in the form of dark (dip type) soliton are found. In the small amplitude approximation, it is found that the dip becomes deeper and narrower as the temperature is raised. In low temperature T ≪mc 2, localized solution exists only if the equilibrium longitudinal fluid velocity (parallel to the direction of propagation) in the wave frame is larger than the classical thermal velocity √T / m of the plasma. For ultra-relativistically high temperature T ≪mc 2, it is shown that dark soliton can exist if the equilibrium longitudinal velocity is larger than c /√ 3. © 2011 American Institute of Physics.

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.

OBJECTIVES: Appetite and carbohydrate metabolism are important contributors to the development of obesity. Recently, low serum amylase was shown to be associated with obesity and metabolic disorder. We investigated the relationship between amylase and ghrelin or peptide YY (PYY) levels in healthy men. METHODS: Twenty-one men were enrolled in this cross-sectional study; all subjects were asymptomatic with no medical history. Fasting serum amylase, ghrelin, PYY3-36, anthropometry, and nutritional intake were measured. Linear regression analyses were performed to examine associations between amylase and ghrelin or PYY3-36. RESULTS: The mean (SD) age and waist circumference of the subjects were 51.5 (10.9) years and 87.0 (4.4) cm, respectively. Amylase was found to be correlated with waist circumference (r = −0.438, P = 0.054), ghrelin (r = 0.533, P = 0.015), and PYY3-36 (r = −0.511, P = 0.021). Multivariate linear regression analysis revealed a negative association between amylase and PYY3-36 (β = −0.428, P = 0.045) but a nonsignificantly positive association between amylase and ghrelin (β = 0.260, P = 0.146). CONCLUSIONS: Amylase levels were found to be associated with ghrelin and PYY3-36 in healthy men. Amylase, ghrelin, and PYY3-36 may play a role in obesity; further research is required to identify the underlying mechanism. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Kyae B.,Pusan National University | Shin C.S.,Asia Pacific Center for Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In order to relax the Landau pole constraint on "λ," which is a coupling constant between a singlet S and the minimal supersymmetric standard model (MSSM) Higgs, λShuhd in the next-to MSSM, and also maintains the gauge coupling unification, we consider perturbative U(1) gauge extensions of the next-to MSSM. For relatively strong U(1) gauge interactions down to low energies, we assign U(1) charges only to the Higgs and the third family of the chiral matter among the MSSM superfields. In the U(1)Z [U(1)Z×U(1)X] extension, the low-energy value of λ can be lifted up to 0.85-0.95 [0.9-1.0], depending on the employed charge normalizations, when λ and the new gauge couplings are required not to blow up below the 1016 GeV energy scale. The introduction of extra vectorlike superfields can induce the desired Yukawa couplings for the first two families of the chiral matter. We also discuss various phenomenological constraints associated with extra U(1) breaking. © 2013 American Physical Society.

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.

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.

Kyae B.,Pusan National University | Park J.-C.,Korea Institute for Advanced Study
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In order to raise the Higgs mass to 125 GeV and relieve the fine-tuning associated with the heavy s-top mass in the minimal supersymmetric standard model, we propose a new singlet extension of the minimal supersymmetric standard model. In this scenario, the additional Higgs mass is radiatively generated in a hidden sector, and the effect is transmitted to the Higgs through a messenger field. The Higgs mass can be efficiently increased by the parameters of the superpotential as in the extra matter scenario, but free from the constraints on extra colored matter fields by the LHC experiments. As a result, the tuning problem can be remarkably mitigated by taking low enough messenger mass (∼300 GeV) and mass parameter scales (∼500 GeV). We also discuss how to enhance the diphoton decay rate of the Higgs over the SM expectation in this framework. © 2013 American Physical Society.

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.

Kim I.-T.,Pusan National University
International Journal of Fatigue | Year: 2013

Blast cleaning treatments are used widely in newly built steel structures to clean forged surfaces and increase the adhesive properties of subsequent coatings. On the other hand, the beneficial effects of a blast cleaning treatment, which are similar to shot peening, on the fatigue strength of welded steel structures are not considered in the fatigue design procedure. In this study, fatigue tests were carried out on as-welded and blast-treated longitudinal fillet welded out-of-plane gusset joints subjected to three different cyclic loading conditions: uniaxial tension, out-of-plane bending and in-plane bending stress cycles. The effect of the blast cleaning treatment on the fatigue strength of the gusset joints was studied. The fatigue tests showed that the blast cleaning treatment increased the fatigue strength of the gusset welded joints, particularly at the lower stress range. A 19% increase in fatigue strength at 2 million cycles and 66% increase in fatigue limit could be realized using the blast cleaning treatment. © 2012 Elsevier Ltd. All rights reserved.

Kim G.H.,Pusan National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2010

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is the most common form of primary extranodal lymphomas. In most cases, it is developed as multifocal and mucosal lesions, and its initial diagnosis is made by biopsy of suspicious lesions on endoscopy. However, when gastric MALT lymphoma afflict submucosal site without typical mucosal lesion, further procedures are necessary for diagnosis, such as endoscopic mucosal resection and endoscopic ultrasonography. We recently experienced two cases of submucosal tumor-like gastric MALT lymphoma. Both cases were without any mucosal lesion. One case was confirmed by endoscopic mucosal resection, and the latter was by wedge resection. Treatment modalities included endoscopic mucosal resection, surgery, H. pylori eradication, and/or chemotherapy. Both cases achieved complete remission until our 18 months' and 16 months' follow up.

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..

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.

Shin H.-J.,Pusan National University | Shin H.-J.,Stanford University | Baker J.,Stanford University | Leveson-Gower D.B.,Stanford University | And 3 more authors.
Blood | Year: 2011

Previous work has demonstrated that both rapamycin (RAPA) and IL-2 enhance CD4+CD25+Foxp3+ regulatory T-cell (Treg) proliferation and function in vitro. We investigated whether the combination of RAPA plus IL-2 could impact acute GVHD induction after bone marrow transplantation (BMT). RAPA plus IL-2 resulted in improved survival and a reduction in acute GVHD lethality associated with an increased expansion of donor type CD4+Foxp3+ Tregs and reduced CD4 +CD25- conventional T cells (Tcons). RAPA plus IL-2, but not either drug alone, increased both expansion of donor natural Tregs and conversion of induced Tregs from donor CD25- Tcons while IL-2 alone increased conversion of Tregs from CD25- Tcon. RAPA plus IL-2 treatment resulted in less production of IFN-γ and TNF, cytokines known to be important in the initiation of acute GVHD. These studies indicate that the pharmacologic stimulation of T cells with IL-2 and the suppression of Tcon proliferation with RAPAresult in a selective expansion of functional Tregs and suppression of acute GVHD. © 2011 by The American Society of Hematology.

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

Ha K.-M.,Pusan National University
Impact Assessment and Project Appraisal | Year: 2016

Not many have realized the close relationship between rumor, looting, and suicide and disaster management, although some researchers have discussed each issue separately. The purpose of this paper is to understand better the nature of these three issues by mainly analyzing them in the context of distinguished models, ‘breaking news’ and the community’s culture when it comes to disaster management. As the key finding, the field of disaster management must not manage rumor, looting, and suicide only as breaking news. Instead, these three issues should be managed under the community’s disaster culture to dispel rumors and provide facts through the mass media and public information officers, penalize cases of looting coupled with education, and support and intervene in cases of suicide. © 2016 IAIA

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.

Kang H.,Pusan National University
Journal of the Korean Astronomical Society | Year: 2011

We calculate the energy spectra of cosmic ray (CR) protons and electrons at a plane shock with quasi-parallel magnetic fields, using time-dependent, diffusive shock acceleration (DSA) simulations, including energy losses via synchrotron emission and Inverse Compton (IC) scattering. A thermal leakage injection model and a Bohm type diffusion coe±cient are adopted. The electron spectrum at the shock becomes steady after the DSA energy gains balance the synchrotron/IC losses, and it cuts off at the equilibrium momentum peq. In the postshock region the cuto momentum of the electron spectrum decreases with the distance from the shock due to the energy losses and the thickness of the spatial distribution of electrons scales as p-1. Thus the slope of the downstream integrated spectrum steepens by one power of p for pbr < p < peq, where the break momentum decreases with the shock age as pbr x t-1. In a CR modified shock, both the proton and electron spectrum exhibit a concave curvature and deviate from the canonical test-particle power-law, and the upstream integrated electron spectrum could dominate over the downstream integrated spectrum near the cutoff momentum. Thus the spectral shape near the cutoff X-ray synchrotron emission could reveal a signature of nonlinear DSA. © 2011 The Korean Astronomical Society. All Rights Reserved.

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.

Im E.,Pusan National University
Journal of Neurogastroenterology and Motility | Year: 2015

The family of corticotropin-releasing factor (CRF) composed of 4 ligands including CRF, urocortin (Ucn) 1, Ucn2, and Ucn3 is expressed both in the central nervous system and the periphery including the gastrointestinal tract. Two different forms of G protein coupled receptors, CRF1 and CRF2, differentially recognize CRF family members, mediating various biological functions. A large body of evidence suggests that the CRF family plays an important role in regulating inflammation and angiogenesis. Of particular interest is a contrasting role of the CRF family during inflammatory processes. The CRF family can exert both proand anti-inflammatory functions depending on the type of receptors, the tissues, and the disease phases. In addition, there has been a growing interest in a possible role of the CRF family in angiogenesis. Regulation of angiogenesis by the CRF family has been shown to modulate endogenous blood vessel formation, inflammatory neovascularization and cardiovascular function. This review outlines the effect of the CRF family and its receptors on 2 major biological events: inflammation and angiogenesis, and provides a possibility of their application for the treatment of inflammatory vascular diseases. © 2015 The Korean Society of Neurogastroenterology and Motility.

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.

Ha D.W.,Pusan National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2011

Recent studies have reported the potentials of endoscopic papillary large balloon dilatation (EPLBD) with minor endoscopic sphincterotomy (EST) for the complete removal of common bile duct (CBD) stone in the high risk groups. However, there have been no reports about the recurrence of the CBD stone after EPLBD with minor EST. The aim of this study was to evlauate the recurrence of CBD stone after EPLBD with minor EST. A total of 1,036 patients who underwent endoscopic treatment due to CBD stones at Pusan University Hospital were enrolled. The patients were classified into two groups: those who underwent EPLBD with minor EST (group 1) and those who underwent EST treatment (group 2). We investigated clinical factors and recurrence rate between two groups. The recurrence of CBD stone occurred in total of 74 patients (7%), and the recurrence rates of CBD stone were 21/321 (6.5%) in Group 1 and 53/715 (7.4%) in Group 2. There were no difference in the presence of diverticulum and the number and size of recurrent CBD stone between the two groups. In case of diverticulum existence, recurrence rates were 12/158 (7.6%) in Group 1 and 21/101 (20.8%) in Group 2. When compared to the case of no diverticulum existence (Group 1: 9/163 [5.5%], Group 2: 32/614 [5.2%]), the recurrence rate of CBD stone was significantly lower if treated after EPLBD with minor EST (p < 0.01). CBD stone that recurs after going through EPLBD with minor EST can be successfully removed with an endoscopic treatment. The recurrence of CBD stone was especially lower in cases with periampullary diverticulum and treated with EPLBD with minor EST. Our results will be helpful in endoscopic retreatment and preventing the recurrence of CBD stone.

Choi J.-Y.,Pusan National University
Journal of Institute of Control, Robotics and Systems | Year: 2013

We consider discrete-time LTI (Linear Time-Invariant) systems with constant input delays. The input delay is modeled by a first-order PdE (Partial difference Equation) and a backstepping transformation is employed to design a predictor feedback controller. The backstepping approach results in the construction of an explicit Lyapunov function, with which we prove the exponential stability of the closed-loop system formed by the predictor feedback. The numerical example demonstrates the design of the predictor feedback controller, and illustrates the validity of the exponential stability. © ICROS 2013.

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.

Kwangha L.,Pusan National University
Tuberculosis and Respiratory Diseases | Year: 2012

Cardiopulmonary resuscitation (CPR) is a series of life-saving actions that improve the chances of survival, following cardiac arrest. Successful resuscitation, following cardiac arrest, requires an integrated set of coordinated actions represented by the links in the Chain of Survival. The links include the following: immediate recognition of cardiac arrest and activation of the emergency response system, early CPR with an emphasis on chest compressions, rapid defibrillation, effective advanced life support, and integrated post-cardiac arrest care. The newest development in the CPR guideline is a change in the basic life support sequence of steps from "A-B-C" (Airway, Breathing, Chest compressions) to "C-A-B" (Chest compressions, Airway, Breathing) for adults. Also, "Hands-Only (compression only) CPR" is emphasized for the untrained lay rescuer. On the basis of the strength of the available evidence, there was unanimous support for continuous emphasis on high-quality CPR with compressions of adequate rate and depth, which allows for complete chest recoil, minimizing interruptions in chest compressions and avoiding excessive ventilation. High-quality CPR is the cornerstone of a system of care that can optimize outcomes beyond return of spontaneous circulation (ROSC). There is an increased emphasis on physiologic monitoring to optimize CPR quality, and to detect ROSC. A comprehensive, structured, integrated, multidisciplinary system of care should be implemented in a consistent manner for the treatment of post-cardiac arrest care patients. The return to a prior quality and functional state of health is the ultimate goal of a resuscitation system of care. Copyright©2012. The Korean Academy of Tuberculosis and Respiratory Diseases. All rights reserved.

This paper presents a general method, which is aimed at identifying both the nonlinear damping and restoring characteristics of nonlinear oscillation systems in which the nonlinear damping is characterized as a function of velocity alone. The method developed for this simultaneous identification involves the non-parametric identification of nonlinear systems. Both system displacement and velocity responses are required for its implementation. However, the numerical approach to this method results in the instability of the numerical solutions, which also means that the solutions identified lack of stability properties. This difficulty is solved by employing a stabilization technique (or regularization). Although the method presented herein is built on the basis of the measurement of the system displacement and velocity responses, a conceptual systematic procedure is also proposed to describe how the system's acceleration response can be used for simultaneous identification. Finally, an example involving a highly nonlinear system is presented to demonstrate the proposed method's workability for simultaneous nonlinear system identification. © 2010 Elsevier Ltd.

Rhee K.W.,Pusan National University
Pediatric Gastroenterology, Hepatology and Nutrition | Year: 2012

The examination of small bowel in Crohn's disease (CD) is very important. Capsule endoscopy (CE) has been recognized as a good tool for evaluation of small bowel. The capsule placement is achieved endoscopically for Children not to swallow capsule. CE is superior to any other modalities for examination of small-bowel. The large portion of pediatric patients with known CD were found with CE to have more extensive and newly diagnostic small-bowel disease. All of them had therapeutic changes. The most side effect of CE is capsule retention. The capsule retention rate in pediatric CD is about 7.3%. The patency capsule helps to predict the possibility of capsule retention. For the improving of the diagnostic accuracy, the experience of more than 20 readings of CE is needed. © 2014 by The Korean Society of Pediatric Gastroenterology, Hepatology and Nutrition.

Kim K.H.,Pusan National University
Korean Journal of Pain | Year: 2013

Varicella (chickenpox) is a highly contagious airborne disease caused by primary infection with the varicella zoster virus (VZV). Following the resolution of chickenpox, the virus can remain dormant in the dorsal sensory and cranial ganglion for decades. Shingles (herpes zoster [HZ]) is a neurocutaneous disease caused by reactivation of latent VZV and may progress to postherpetic neuralgia (PHN), which is characterized by dermatomal pain persisting for more than 120 days after the onset of HZ rash, or "well-established PHN", which persist for more than 180 days. Vaccination with an attenuated form of VZV activates specific T-cell production, thereby avoiding viral reactivation and development of HZ. It has been demonstrated to reduce the occurrence by approximately 50-70%, the duration of pain of HZ, and the frequency of subsequent PHN in individuals aged > 50 years in clinical studies. However, it has not proved efficacious in preventing repeat episodes of HZ and reducing the severity of PHN, nor has its long-term efficacy been demonstrated. The most frequent adverse reactions reported for HZ vaccination were injection site pain and/or swelling and headache. In addition, it should not be administrated to children, pregnant women, and immunocompromised persons or those allergic to neomycin or any component of the vaccine. © The Korean Pain Society, 2013.

Son S.M.,Pusan National University
Diabetes and Metabolism Journal | Year: 2012

Macrovascular and microvascular diseases are currently the principal causes of morbidity and mortality in subjects with diabetes. Disorders of the physiological signaling functions of reactive oxygen species (superoxide and hydrogen peroxide) and reactive nitrogen species (nitric oxide and peroxynitrite) are important features of diabetes. In the absence of an appropriate compensation by the endogenous antioxidant defense network, increased oxidative stress leads to the activation of stress-sensitive intracellular signaling pathways and the formation of gene products that cause cellular damage and contribute to the vascular complications of diabetes. It has recently been suggested that diabetic subjects with vascular complications may have a defective cellular antioxidant response against the oxidative stress generated by hyperglycemia. This raises the concept that antioxidant therapy may be of great benefit to these subjects. Although our understanding of how hyperglycemia-induced oxidative stress ultimately leads to tissue damage has advanced considerably in recent years, effective therapeutic strategies to prevent or delay the development of this damage remain limited. Thus, further investigation of therapeutic interventions to prevent or delay the progression of diabetic vascular complications is needed.

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.

Yang H.,Pusan National University
Current Opinion in Chemical Biology | Year: 2012

Signal amplification in conventional enzyme-based biosensors is not high enough to achieve the ultrasensitive detection of biomolecules. In recent years, signal amplification has been improved by combining enzymatic reactions with redox cycling or employing multienzyme labels per detection probe. Electrochemical-chemical redox cycling and electrochemical-chemical-chemical redox cycling allow ultrasensitive detection simply by including one or two more chemicals in a solution without the use of an additional enzyme and/or electrode. Multiple horseradish peroxidase labels on magnetic bead carriers provide high signal enhancement along with a multiplex detection possibility. In both cases, the detection procedures are the same as those in conventional enzyme-based electrochemical sensors. © 2012 Elsevier Ltd.

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.

Shchipunov Y.,Pusan National University
Pure and Applied Chemistry | Year: 2012

Bionanocomposites are a novel class of nanosized materials. They contain the constituent of biological origin and particles with at least one dimension in the range of 1-100 nm. There are similarities with nanocomposites but also fundamental differences in the methods of preparation, properties, functionalities, biodegradability, biocompatibility, and applications. The article includes two parts. Bionanocomposite definition and classification along with nanoparticles, biomaterials, and methods of their preparation are initially reviewed. Then, novel approaches developed by our team are presented. The first approach concerns the preparation of bionanocomposites from chitosan and nanoparticles. It is based on the regulated charging of polysaccharide by the gradual shift of solution pH. When charges appear, the biomacromolecules come into the electrostatic interactions with negatively charged nanoparticles that cause the jellification of solutions. It is also applied to form films. They have a nacre-like structure from stacked planar nanoparticles separated by aligned biomacromolecules. The second approach deals with the biomimicking mineralization of biopolymers by using a novel silica precursor. Its advantage over the current sol-gel processing is in the compatibility and regulation of processes and structure of generated silica. Another example of the mineralization is presented by titania. Syntheses are performed in anhydrous ethylene glycol. Processes and structure of bionanocomposites are regulated by water that is added in an amount to only hydrate functional groups in the carbohydrate macromolecule. © 2012 IUPAC.

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.

Shin Y.-I.,University Hospital Freiburg | Shin Y.-I.,Pusan National University | Foerster T.,University Hospital Freiburg | Nitsche M.A.,University Hospital Freiburg
Neuropsychologia | Year: 2015

Non-invasive brain stimulation is a versatile tool to modulate psychological processes via alterations of brain activity, and excitability. It is applied to explore the physiological basis of cognition and behavior, as well as to reduce clinical symptoms in neurological and psychiatric diseases. Neuromodulatory brain stimulation via transcranial direct currents (tDCS) has gained increased attention recently. In this review we will describe physiological mechanisms of action of tDCS, and summarize its application to modulate psychological processes in healthy humans and neuropsychiatric diseases. Furthermore, beyond giving an overview of the state of the art of tDCS, including limitations, we will outline future directions of research in this relatively young scientific field. © 2015 Elsevier Ltd.

Ramasamy P.,Kongju National University | Mamum S.I.,Kongju National University | Jang J.,Pusan National University | Kim J.,Kongju National University
CrystEngComm | Year: 2013

High quality Mn-doped CdTe nanorods with uniform diameter were synthesized in aqueous phase by spontaneous self-organization of Mn-doped CdTe nanoparticles into nanorods. The diameter of the CdTe nanorods increased gradually from 4.1 to 10.2 nm for 0-4.2% Mn incorporations. The intermediate step in the nanorod growth was found to be double or triple chain aggregation. The X-ray diffraction (XRD) patterns of the Mn doped samples retained the same crystal structure as the CdTe nanocrystals, indicating no second phase formation for Mn ion. XPS, ICP-AES and ESR data demonstrate successful incorporation of Mn ions in CdTe nanorods. Superconducting quantum interference device (SQUID) measurements reveal that all of these nanocrystals exhibited ferromagnetic behavior, with a coercive field (Hc) of 2.6 kOe. © 2013 The Royal Society of Chemistry.

Park S.H.,Pusan National University
Acta Mathematica Scientia | Year: 2014

In this paper, we investigate the influence of boundary dissipation on the decay property of solutions for a transmission problem of Kirchhoff type wave equation with boundary memory condition. By introducing suitable energy and Lyapunov functionals, we establish a general decay estimate for the energy, which depends on the behavior of relaxation function. © 2014 Wuhan Institute of Physics and Mathematics.

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.

Im D.,Korea Advanced Institute of Science and Technology | Nam I.,Pusan National University | Lee K.,Korea Advanced Institute of Science and Technology
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

A wideband active feedback single-to-differential (S-to-D) low-noise amplifier (LNA) for digital TV (DTV) tuners composed of a S-to-D converter, a voltage combiner, and a negative feedback network is proposed to achieve low noise as well as to improve the linearity performances (IIP2 and IIP3) simultaneously. By feeding the single-ended output of the voltage combiner, which is used for combining the differential output of the S-to-D converter, to the input of the LNA through the feedback network, a wideband S-to-D LNA exploiting negative feedback is implemented. The differential mode operation of the voltage combiner reduces the second-order nonlinearity feedback, allowing us to improve both the IIP3 and IIP2 of the LNA at the same time. Two LNA design examples are presented to demonstrate usefulness of the proposed approach. The LNA I, by adopting a common source (CS) amplifier with a common gate, common source (CGCS) balun load as the S-to-D converter, is able to achieve a high gain and a low noise figure (NF) by increasing the loop gain. The LNA II using the differential amplifier with the ac-grounded second input terminal is designed for robust IIP2 to PVT variations. © 2010 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.

Kwon S.M.,Pusan National University
Advances in experimental medicine and biology | Year: 2012

The Notch signaling pathway is evolutionarily conserved and has been associated with numerous developmental processes, including stem cell maintenance and adult tissue homeostasis. Notably, both abnormal increases and deficiencies of Notch signaling result in human developmental anomalies and cancer development implying that the precise regulation of the intensity and duration of Notch signals is imperative. Numerous studies have demonstrated that the aberrant gain or loss of Notch signaling pathway components is critically linked to multiple human diseases. In this chapter, we will briefly summarize the molecular basis of Notch signaling, focusing on the modulation of Notch signals, and its developmental outcomes including vessel formation and the onset of cancer.

Yoon T.-H.,Pusan National University
Journal of the Korean Medical Association | Year: 2013

Health equity is not just concerned with health care; rather, it is an issue of fairness and social justice. Equity-oriented health policies have increasingly been recognized as important public health issues for the last decades. This study investigates the blueprints for health equity policy that have been made in several developed countries or international organizations. From the late 1990s, national committees in the UK, the Netherlands, and Sweden have proposed comprehensive policies to strengthen health equity. In addition, the World Health Organization and its European regional office have developed policies for their member countries. Several lessons can be drawn from a review of the major blueprints: 1) setting attainable and quantitative targets, 2) action across all the social determinants of health, not just health care services, 3) giving the best start in early life for all children, 4) building equity-oriented universal health care systems, 5) political commitment, 6) participation and democratic decision making at the local level, and 7) monitoring and evaluation of health inequalities and their determinants. © Korean Medical Association.

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.

Hyun S.S.,Pusan National University
Cornell Hospitality Quarterly | Year: 2010

The focus of this research was the chain restaurant industry, and its purpose was to (1) determine which factors influence relationship quality and customer loyalty formation and (2) examine the connections between relationship quality and loyalty. Based on the literature review, five dimensions influence restaurant patrons' behavior: food quality, service quality, price, location, and environment. Theoretical relationships between attributes influencing patrons' behavior, relationship quality, and loyalty were derived from the literature review. Data analysis indicated that these five attributes influence loyalty formation, with impact mediated by relationship quality. They also influence customer satisfaction, with satisfaction influencing loyalty formation directly and indirectly via trust. Furthermore, service quality was the only attribute to directly and indirectly affect trust, and its effect is stronger than that of any other attribute. Managerial implications are discussed. © 2010 Cornell University.

Observation of temporal variations in soil moisture along transects is important when examining hydrological processes on a hillslope. Although there is substantial interest in characterizing catchment hydrology through an investigation of hydrologic connectivity, few attempts have been made to explore hydrologic connectivity within soil layers using soil moisture observations. Mathematical relationships among soil moisture differences are reproducible when Granger causality is defined within the context of hydrological connectivity because the process based transfer functions facilitate soil moisture predictions. Soil moisture time series along two transects on a steep hillslope were obtained using a multiplexed time domain reflectometry system during the growing season in June 2008 and 2009. The transfer function relationships between multiple soil moisture differences were delineated to determine a representative point for reliable time series modeling, and to establish the spatial pattern of areal clusters that will enable model identification and prediction. The impact of hillslope topography on the modeling of coupled soil moisture was highlighted by configuring the threshold behavior of model predictability. Results showed that soil moisture temporal relationships can be used for the prediction of volumetric soil moisture, within a specific area associated with representation point. Reliable relationships among soil moistures were apparent for points having greater upslope areas between 400m2 and 1000m2. © 2013 Elsevier B.V.

Parent B.,Pusan National University
Journal of Computational Physics | Year: 2012

A new class of flux-limited schemes for systems of conservation laws is presented that is both high-resolution and positivity-preserving. The schemes are obtained by extending the Steger-Warming method to second-order accuracy through the use of component-wise TVD flux limiters while ensuring that the coefficients of the discretization equation are positive. A coefficient is considered positive if it has all-positive eigenvalues and has the same eigenvectors as those of the convective flux Jacobian evaluated at the corresponding node. For certain systems of conservation laws, such as the Euler equations for instance, this condition is sufficient to guarantee positivity-preservation. The method proposed is advantaged over previous positivity-preserving flux-limited schemes by being capable to capture with high resolution all wave types (including contact discontinuities, shocks, and expansion fans). Several test cases are considered in which the Euler equations in generalized curvilinear coordinates are solved in 1D, 2D, and 3D. The test cases confirm that the proposed schemes are positivity-preserving while not being significantly more dissipative than the conventional TVD methods. The schemes are written in general matrix form and can be used to solve other systems of conservation laws, as long as they are homogeneous of degree one. © 2011 Elsevier Inc.

Hein G.,University of Zurich | Morishima Y.,University of Zurich | 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.

Park S.Y.,Catholic University of Korea | Baik H.J.,Catholic University of Korea | Oh Y.T.,Yonsei University | Oh K.T.,Chung - Ang University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

Sharper image: A newly developed polysaccharide/drug conjugate (see picture) responds to changes in pHa value and was shown to penetrate HeLa tumors in mice as determined by fluorescence imaging. It has the potential to be used in photodynamic therapy, thereby targeting the tumor while having no detrimental effects on the surrounding tissue. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The authors report a case of acute kidney injury (AKI) resulting from menstruation-related disseminated intravascular coagulation (DIC) in an adenomyosis patient. A 40-yr-old woman who had received gonadotropin for ovulation induction therapy presented with anuria and an elevated serum creatinine level. Her medical history showed primary infertility with diffuse adenomyosis. On admission, her pregnancy test was negative and her menstrual cycle had started 1 day previously. Laboratory data were consistent with DIC, and it was believed to be related to myometrial injury resulting from heavy intramyometrial menstrual flow. Gonadotropin is considered to play an important role in the development of fulminant DIC. This rare case suggests that physicians should be aware that gonadotropin may provoke fulminant DIC in women with adenomyosis.

Veeranarayana Reddy M.,Pukyong National University | Reddy G.C.S.,Pusan National University | Jeong Y.T.,Pukyong National University
Tetrahedron | Year: 2012

An efficient, rapid, and green synthesis of 2H-indazolo[2,1-b]phthalazine- triones has been accomplished under solvent-free conditions by the reaction of phthalhydrazide, aldehydes and 5,5-dimethylcyclohexane-1,3-dione. This approach exploits the synthetic potential of microwave irradiation and Montmorillonite K-10 combination and offers many advantages, such as excellent product yields, shorter reaction time, reusable catalyst, easy isolation of products, and environmentally benign reaction conditions. © 2012 Elsevier Ltd. All rights reserved.

Kim S.H.,Pusan National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2012

Anomalous union of the pancreaticobiliary duct (AUPBD) is a congenital anomaly that is defined as a junction of the bile duct and pancreatic duct outside the duodenal wall. This anomaly results in a loss of normal sphincteric mechanisms at the pancreaticobiliary junction. As a result, regurgitation of pancreatic juice into the biliary system develops and causes choledochal cysts, choledocholithiasis, cholangitis, pancreatitis and malignancy of the biliary tract. Gallbladder cancer or common bile duct cancer associated with AUPBD and choledochal cysts have been frequently reported. But, intrahepatic cholangiocarcinoma associated with this condition has been only rarely reported. Here, we report a case of intrahepatic cholangiocarcinoma associated with AUPBD and choledochal cyst.

Pyo J.,Pusan National University
Differential Geometry and its Application | Year: 2016

In this paper, we consider compact translating solitons with non-empty planar boundary. Each boundary component lies in a plane which is orthogonal to the translating direction. We firstly prove that when the planar boundary is either a circle or convex and the translating soliton meets the plane containing the boundary with a constant angle, then the compact translating soliton is part of an entire rotationally symmetric strictly convex graphical surface. Secondly, we show that a compact translating soliton spanning two horizontal planar Jordan curves inherits the symmetries of its boundary. We also show a balancing type formula for compact translating solitons with planar boundary. © 2016 Elsevier B.V.

Jeong Y.I.,Pusan National University
International journal of nanomedicine | Year: 2011

Polymeric micelles using amphiphilic macromolecules are promising vehicles for antitumor targeting. In this study, we prepared anticancer agent-incorporated polymeric micelles using novel block copolymer. We synthesized a block copolymer composed of dextran and poly (DL-lactide-co-glycolide) (DexbLG) for antitumor drug delivery. Doxorubicin was selected as the anticancer drug, and was incorporated into polymeric micelles by dialysis. Polymeric micelles were observed by transmission electron microscopy to be spherical and smaller than 100 nm, with a narrow size distribution. The particle size of doxorubicin-incorporated polymeric micelles increased with increasing drug content. Higher initial drug feeding also increased the drug content. During the drug-release study, an initial burst release of doxorubicin was observed for 10 hours, and doxorubicin was continuously released over 4 days. To investigate the in vitro anticancer effects of the polymeric micelles, doxorubicin-resistant HuCC-T1 cells were treated with a very high concentration of doxorubicin. In an antiproliferation study, the polymeric micelles showed higher cytotoxicity to doxorubicin-resistant HuCC-T1 cells than free doxorubicin, indicating that the polymeric micelles were effectively engulfed by tumor cells, while free doxorubicin hardly penetrated the tumor cell membrane. On confocal laser scanning microscopy, free doxorubicin expressed very weak fluorescence intensity, while the polymeric micelles expressed strong red fluorescence. Furthermore, in flow cytometric analysis, fluorescence intensity of polymeric micelles was almost twice as high than with free doxorubicin. DexbLG polymeric micelles incorporating doxorubicin are promising vehicles for antitumor drug targeting.

Leem J.W.,Kyung Hee University | Song Y.M.,Pusan National University | Yu J.S.,Kyung Hee University
Nanoscale | Year: 2013

We report the biomimetic artificial silicon (Si) compound eye structures for broadband and wide-angle antireflection by integrating nanostructures (NSs) into periodically patterned microstructures (p-MSs) via thermal dewetting of gold and subsequent dry etching. The truncated cone microstructures with a two-dimensional hexagonal symmetry pattern were fabricated by photolithography and dry etching processes. The desirable shape and density of the nanostructures were obtained by controlled dewetting. The incorporation of p-MSs into the NS/Si surface further reduced the surface total reflectance over a wide wavelength range of 300-1030 nm at near normal incidence, indicating the average reflectance (Ravg) and solar weighted reflectance (RSWR) values of ∼2.5% and 2%, respectively, compared to the only NSs on the flat Si surface (i.e., Ravg ∼ 4.9% and RSWR ∼ 4.5%). Additionally, the resulting structure improved the angle-dependent antireflection property due to its relatively omnidirectional shape, which exhibited the Ravg < 4.3% and RSWR < 3.7% in the wavelength region of 300-1100 nm even at a high incident light angle of 70°in the specular reflectance. © 2013 The Royal Society of Chemistry.

Cho S.-B.,Corporate Randnter | Kim H.,Pusan National University
Optics Express | Year: 2016

The practical realization of long-distance entanglement-based quantum communication systems strongly rely on the observation of highly stable quantum interference between correlated single photons. This task must accompany active stabilization of the optical path lengths within the single-photon coherence length. Here, we provide two-step interferometer stabilization methods employing continuous optical length control and experimentally demonstrate two-photon quantum interference using an actively stabilized 6-km-long fiber-optic Hong-Ou-Mandel interferometer. The two-step active control techniques are applied for measuring highly stable two-photon interference fringes by scanning the optical path-length difference. The obtained two-photon interference visibilities with and without accidental subtraction are found to be approximately 90.7% and 65.4%, respectively. ©2016 Optical Society of America.

Kim S.,Pusan National University
Water Resources Research | Year: 2014

Field monitoring of isotopes and isotope analyses have been used to approximate water travel time at hillslope scales. This paper introduces an alternate method for estimating a point-scaled transit time in a soil layer, namely hydrometric transit time (HTT). HTT uses hydrometric measurements to address both matrix flow and bypass flow. Soil matrix flux is approximated through integration of continuous soil moisture profiles and soil water computations. Free surface film modeling of unsaturated flow is used to estimate bypass flow. This flux and storage estimation scheme is applied to a steep hillslope using hydrometric measurements that were estimated over an 8 month period using a continuous daily approximation of soil moisture profiles. Transit times at several designated points are also evaluated using isotope analyses. Results show that rainfall strongly controls temporal fluctuations. This work highlights the potential role of HTT in revealing the spatial and seasonal variations in the transit time probability density function (PDF) along transects. Mean transit time does not sufficiently characterize transit time variations on a hillslope scale. Accumulated flux distributions identify distinct hydrologic contributions and efficient redistribution of soil water in the downslope area of the hillside. ©2014. American Geophysical Union.

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.

Lim H.-C.,Pusan National University | Jeong T.-Y.,Pukyong National University
Energy | Year: 2010

For the feasibility study of a wind energy site, accurate information on the flow field within the given full-scale site is a prerequisite. Two 2-D ultrasonic anemometers and one cup anemometer, located perpendicular to the prevailing wind direction, were used to measure the mean and instantaneous wind velocities at a height of 4.5 m. The experiments showed that the Reynolds number was about 6.7 × 105 (based on the sensor height and the wind velocity) and the friction velocity, u* about 0.32 ms-1. The power-spectrum analysis on horizontal and vertical wind speed was conducted over a wide range of frequencies by joining together various portions of the spectrum. There appeared to be four major eddy-energy peaks in the spectrum; each peak occurred at periods of about 1 or 2 min, 8 h, 24 h and 100 h. Between the peaks, a broad spectral gap was centered at a frequency ranging from 0.2 to 10 cycles per hour. On the basis of an overall analysis of the short-term data measured in Wol-Ryong, Jeju Island, it is concluded that for the development of future wind energy resources, the Wol-Ryong site is a good candidate for a future wind energy site. © 2010 Elsevier Ltd.

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.

Kim K.,Sangmyung University | Cho Y.-H.,RandD Team | Shin H.-C.,Pusan National University
Journal of Power Sources | Year: 2013

1-Ethyl-1-methyl piperidinium bis(trifluoromethanesulfonyl)imide (EMP-TFSI) is an ionic liquid with a melting temperature of 85 °C. Although it is a solid salt, it shows good miscibility with carbonate solvents, which allows EMP-TFSI to be used as a co-solvent in these systems. Ethylene carbonate is another solid co-solvent used in Li-ion batteries. Due to its smaller cationic size, EMP-TFSI provides better conductivity as a co-solvent than 1-methyl-1-propyl piperidinium bis(trifluoromethanesulfonyl)imide (MPP-TFSI), which is the smallest room-temperature piperidinium liquid salt known. In cells with 50 wt% IL and 50 wt% carbonate electrolyte, an EMP-TFSI mixed electrolyte performs better than an MPP-TFSI mixed electrolyte. Additionally, the discharge capacity values obtained from rate capability tests carried out with mixed EMP-TFSI are as good as those conducted with a pure carbonate electrolyte. © 2012 Elsevier B.V. All rights reserved.

Ko Y.,LG Corp | Park S.,LG Corp | Jin S.,LG Corp | Kim B.,LG Corp | Jeong J.H.,Pusan National University
Applied Energy | Year: 2013

A conventional heat pump exhibits performance degradation even though larger heating capacity is needed as the outdoor temperature declines. As a way to prevent the performance degradation, a heat pump with an inverter-driven two-stage rotary compressor and vapor injection (VI) cycle was investigated for an air-to-water heat pump (AWHP) system employing a flash tank. The volume ratio of two cylinder of a two-stage rotary compressor has significant effect on the performance of the AWHP so that it was experimentally investigated. Based on this result, a two-stage rotary compressor designed with an optimized volume ratio was manufactured and incorporated into the AWHP system. It was found that the VI AWHP system improved the heating capacity by 48% and the COP by 36% compared to those values for the conventional AWHP at water temperature of 60°C and ambient temperature of -15°C. This VI AWHP system can be used for cold climate applications. © 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 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.

Jung Y.-S.,Pusan National University
Biological and Pharmaceutical Bulletin | Year: 2015

Methionine is an essential sulfur-containing amino acid that is metabolized mainly in the liver, where it is converted to S-adenosylmethionine (SAM) by methionine adenosyltransferase. Importantly, SAM is a metabolically pleiotropic molecule that participates in three types of biochemical reactions; transmethylation, transsulfuration (which results in the transfer of sulfur from methionine to serine to form cysteine), and amino propylation (to synthesize polyamines). Critical roles of SAM in the liver have been extensively studied using transgenic animals with chronically reduced or increased hepatic SAM levels. Interestingly, both models with abnormal hepatic SAM concentrations develop liver disease suggesting that SAM homeostasis plays a pivotal role in liver disease. The transsulfuration pathway is connected to the production of glutathione (GSH), which has potent antioxidant capacity in the liver. Accumulating data show that GSH depletion renders the liver vulnerable to oxidative stress and prone to progression of liver disease. In this review, we highlight the importance of homeostasis in the metabolism of sulfur-containing amino acids with a particular focus on the transsulfuration pathway which could be a promising therapeutic target in liver injury. © 2015 The Pharmaceutical Society of Japan.

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.

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.

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.

Kang Y.H.,Pusan National University
The Tohoku journal of experimental medicine | Year: 2010

Vascular calcification refers to the deposition of calcium phosphate in cardiovascular tissues, including arteries and myocardium. Vascular calcification is frequently associated with cardiovascular disease. Recently, bone morphgenetic protein-7 (BMP-7) has been proposed to play an inhibitory role in vascular calcification, but its inhibitory effect has not been fully elucidated. We therefore tested the hypothesis that BMP-7 inhibits vascular calcification by using two conditions, high levels of vitamin D and phosphate, each of which could enhance vascular calcification. C57BL/6 mice were treated for 3 days with high vitamin D (500,000 IU/kg/day) in the presence or absence of recombinant human BMP-7 (rhBMP-7). Expression levels of osteopontin and osteocalcin, markers of the osteoblastic phenotype, were assessed by immunohistochemical staining or Western blotting analysis. Vitamin D increased calcium staining in thoracic aortas and hearts and the expression levels of osteopontin and osteocalcin in mice. Importantly, pretreatment for 7 days and subsequent treatment for 3 days with rhBMP-7 (10 microg/kg/day) abolished the vitamin D-mediated increases in the above parameters. In addition, human aortic smooth muscle cells (HASMCs) were cultured with high beta-glycerophosphate, a phosphate donor, for 2 weeks in the presence or absence of rhBMP-7. High beta-glycerophosphate increased expression levels of osteopontin and osteocalcin as well as calcium staining in HASMCs, but these changes were attenuated by treatment with BMP-7. Thus, BMP-7 inhibits vascular calcification associated with high levels of vitamin D or phosphate. We propose that BMP-7 treatment may be helpful in reducing the risks of cardiovascular disease related to vascular calcification.

Background: The preoperative detection of emphysema like changes (ELCs) is necessary for the successful treatment of pneumothorax. High resolution computed tomography (HRCT) has been used for the preoperative detection of ELCs. However, the traditional HRCT method uses only the axial view, which is perpendicular to the distribution of ELCs. This is not an ideal diagnostic method for the evaluation of ELCs.Methods: Forty-eight patients with pneumothorax had multi-detector computed tomography (MDCT) reconstruction using the coronal view. ELCs were evaluated in the axial and coronal view by a radiologist. A surgeon performed intra-operative examinations of the ELCs. The sensitivity of the different views was compared.Results: The detection sensitivity was 74.4% (70/94) for the axial view and 91.5% (86/94) for the axial-coronal combined view. The intra-operative detection rate was 95.7% (90/94). The preoperative detection of ELCs on the axial-coronal combined view was significantly higher than on the conventional axial view alone (p < 0.01).Conclusions: Evaluation of ELCs on the axial and coronal combined HRCT improved the sensitivity of preoperative detection of ELCs compared to the conventional single axial HRCT. This increased sensitivity will help decrease the recurrence with VATS. © 2011 Kim; licensee BioMed Central Ltd.

Annual time series for spatially distributed soil moisture measurements are useful for identifying water distribution control factors on a hillslope scale. In this intensive 1-year field study of soil moisture on a permanent channel initiation point hillslope, high resolution digital elevation models (DEMs) of surface and bedrock, were used to analyze time series of soil moisture spatial distributions for 19 terrain indices. In linear correlations, observed soil moisture patterns were best explained by local slope and distance to channel. In nonparametric analyses, contributing area and topographic wetness index provided significant correlations to soil moisture. Terrain based modeling hypotheses were tested on time scales between 2. h and 32. days. Soil moisture time series response patterns were classified into distinct patterns based on genetic calibration of recession models and hydrologic implications. Relatively high predictability of soil moisture via topographic characteristics is attributed to high-resolution soil moisture and terrain data. © 2012 Elsevier B.V..

The vertical and lateral profiles of temporal variations in soil moisture are important for understanding the hydrological process along hillside transects. In this study, relationships among measured soil moistures were explored to configure the hydrological contributions of different flowpaths. All the measured soil moistures included a common stochastic structure because rainfall, the hydrometeological driver, is the main factor that determines the soil moisture response feature, and the infiltration process through the topsoil at a shallow depth is also common in all measured soil moisture histories. Therefore, the relationships between the measured series are also affected by both rainfall and topsoil infiltration. The common stochastic structure of the soil moisture series was removed via a prewhitening procedure. A systematic analysis procedure is presented to delineate the exclusive causal relationships among multiple soil moisture measurements. A monitoring system based on multiplexed time domain reflectometry was used to obtain soil moisture time series along two transects on a steep hillslope during the rainy season. The application of the proposed method for monitoring points in two adjacent locations provided 8, 12, 14, and 13, 16, 22 causal relationships for vertical, lateral in parallel, and diagonal directions, respectively, along the two transects. The point-based contributions of the internal flowpath can be evaluated as the correlation is normalized in the context of inflow and outflow. The hydrological processes in the soil layer, vertical flow, lateral flow, downslope recharge, and return flow were quantified, and the relative importance of each hydrological component was determined to improve our understanding of the hydrological processes along the two transects of the study area. © 2011 John Wiley & Sons, Ltd.

Min J.K.,Pusan National University | Lee C.-H.,Korea Advanced Institute of Science and Technology
Journal of Power Sources | Year: 2012

The operating temperature of sodium-sulfur battery cells is above 300 °C for use in molten liquid state electrodes. In order to achieve this high operating temperature condition in a battery module composed of multiple cells, a thermal management system, such as an electric heater and insulation, is essential. The efficiency of the module is directly dependent upon the temperature uniformity inside the module and the heat dissipation from the casing. In the present study, a new numerical model for the thermal analysis of a sodium-sulfur battery module is suggested. The equivalent thermal properties of the cell are evaluated by detailed thermal analysis on the cell. The heat generation of the cell is modeled considering the electrochemical reaction process and the variation of the resistance of the battery. Using these equivalent thermal models of the cell, a zero dimensional lumped thermal model for examining the effects of insulation and heater operation is developed. Finally, the three-dimensional temperature distribution inside the battery module is predicted by solving the thermal energy conservation equation numerically. The distribution of temperature and the thermal energy efficiency of the battery module for various design variables, such as cell arrangement and heater operations, are summarized. © 2012 Elsevier B.V. All rights reserved.

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.

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.

The probability of additional offspring with a beneficial reversal allele for growing to a size NC for a range of population sizes N, sequence lengths L, selective advantages s, and measuring parameters C was calculated for a haploid, asexual population in the coupled discrete-time mutation-selection model in an asymmetric sharply-peaked landscape with a positive selective advantage of the reversal allele over the optimal allele. The growing probability in the stochastic region was inversely proportional to the measuring parameter when C < 1/Ns, bent when C ≈ 1/Ns and saturated when C > 1/Ns. The crossing time and the time dependence of the increase in relative density of the reversal allele in the coupled discrete-time mutation-selection model was approximated using the Wright-Fisher two-allele model with the same selective advantage and corresponding effective mutation rate. The growth behavior of additional offspring with the reversal allele in the asymmetric sharply-peaked landscape in the coupled discrete-time mutation-selection model was controlled by the selective advantage of the reversal allele compared to the optimal allele and could be described by using the Wright-Fisher two-allele model, in spite of there being many other alleles with lower fitness, and in spite of there being two alleles, the optimal and reversal allele, separated by a low-fitness valley with a tunable depth and width. © 2013 The Korean Physical Society.

Lee N.C.,Pusan National University
Journal of the Korean Physical Society | Year: 2013

A fully relativistic multi-component plasma is considered as a template system for generic plasmas, and a reductive perturbation analysis is applied to the system up to the second and the third order to obtain partial differential equations that describe the evolution of the first-order (φ{symbol} 1) and the second-order (φ{symbol} 2) electrostatic potential waves. The secular-free one-soliton solution of the derived equations is obtained by using Kodama and Taniuti's method [J. Phys. Soc. Jpn. 45, 29898 (1978)]. The results of present paper are generic in the sense that they are independent of any specificity of the parameters of the physical system because they are derived without making any restrictive assumptions on the system parameters. The presented results are applicable to any kind of multi-component plasma system because all constituent species are treated on equal mathematical footings throughout the analyses until the final specification is made for the system parameters. The algebraic results are so general that they can even be applied to nonrelativistic plasmas when appropriate nonrelativistic approximations are made to the final expressions. Thus, the presented result can be considered as a template for the one-soliton solution that can used for a large class of different plasma systems. To demonstrate the utility of the template, we specialize the generic results to a relativistically hot electron-positron pair plasma where each species has a different temperature. The general result is also applied to a three-component plasma composed of a relativistically hot electron-positron pair plasma with small fraction of ions. The third order corrections to the KdV solitons of the examples are presented. © 2013 The Korean Physical Society.

Park M.H.,Silla University | Han J.-S.,Pusan National University
Journal of Medicinal Food | Year: 2015

Recently, there has been a growing interest in alternative therapies and in the therapeutic use of natural products for the treatment of diabetes. Therefore, in this study, we investigated the hypoglycemic and hypolipidemic effects of brown algae, Padina arborescens, in an animal model of type 2 diabetes. For 6 weeks, male C57BL/KsJ-db/db mice were administrated either control diet with no treatment or were treated with rosiglitazone (RG; 0.005%, w/w) or P. arborescens extract (PAE; 0.5%, w/w). At the end of the experimental period, the blood glucose levels, glycosylated hemoglobin levels, and plasma insulin levels were significantly lower in the RG and PAE groups compared with the control group. In addition, glucose tolerance was significantly improved in the RG and PAE groups. The homeostatic index of insulin resistance was lower in the RG and PAE groups than the diabetic control group. Also, the total cholesterol, LDL-cholesterol, triglyceride, and free fatty acid levels were lower in the PAE group than in the control group, whereas the HDL-C level was higher in the PAE group. Supplementation with PAE significantly lowered hepatic glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities, and increased glucokinase activity in the liver. Consequently, these results suggest that PAE may be beneficial in improving insulin resistance, hyperglycemia, and dyslipidemia in type 2 diabetics. © Copyright 2015, Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition.

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.

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.

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.

Im D.-S.,Pusan National University
Acta Pharmacologica Sinica | Year: 2010

Previous studies on lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) using various approaches have shown that both the molecules can act as intercellular signaling molecules. The discovery of the Edg subfamily of G-protein-coupled receptors (GPCRs) (later renamed LPA 1-3 and S1P 1-5) for these molecules has opened up a new avenue for pathophysiological research on lysophospholipids. Genetic and molecular studies on lysophospholipid GPCRs have elucidated pathophysiological impacts and roles in cellular signaling pathways. Recently, lysophospholipid GPCR genes have been used to develop receptor subtype-selective agonists and antagonists. The discovery of FTY720, a novel immune modulator, along with other chemical tools, has provided a means of elucidating the functions of each lysophospholipid GPCR on an organ and the whole body level. This communication attempts to retrospectively review the development of agonists and antagonists for lysophospholipid GPCRs, provide integrated information on pharmacological tools for lysophospholipid GPCR signaling, and speculate on future drug development. © 2010 CPS and SIMM All rights reserved.

Kang D.W.,Pusan National University | Choi K.-Y.,Yonsei University | Min D.S.,Yonsei University
Cancer Research | Year: 2011

Phospholipase D (PLD) has been increasingly recognized as a critical regulator of cell proliferation and tumorigenesis. PLD regulates downstream effectors by generating phosphatidic acid (PA), and the expression and activity of PLD are elevated in many different types of human cancer. Aberrant activation of Wnt/b-catenin signaling, followed by hyper-activation of target genes, is linked to a wide range of cancers. New studies reveal a direct connection between the PLD and the Wnt signaling pathways; PLD is a transcriptional target of β-catenin/ T-cell factor (TCF) and reinforces Wnt/β-catenin signaling related with cellular transformation. In this review, we discuss the emerging importance of PLD and PA in the Wnt/β-catenin signaling network, which is associated with tumorigenesis, and suggest that the PLD/PA signaling pathway is a potential therapeutic target for the treatment of cancer. © 2011 American Association for Cancer Research.

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.

Park N.C.,Pusan National University
Journal of the Korean Medical Association | Year: 2016

Sperm banking is an important option to maintain the male fertilization capacity or induce pregnancy even though under the era of in vitro fertilization. The medical indications for sperm banking are generally consisted of 3 categories. There are cases on planning the permanent contraception like vasectomy or cancer patients to be scheduled the chemotherapy or radiotherapy as first category, male infertile patients with severe oligozoospermia or artificially harvested sperm ie, from microscopic epididymal sperm aspiration or testicular sperm extraction et cetera for the artificial insemination with husband sperm as second category, and the therapeutic donor insemination as third category. Of these three categories, the sperm donation program accompanies various complicated practical, ethical and legal issues. Therefore, highly regulated statements are mandatory in order to secure safety and the complete practices for voluntary sperm donors and infertile couples both. In aspect of administrative structure of sperm bank, there are 3 types that are national based to be established in the most of European countries and China, public based in Japan, and commercially available in the USA. Additionally, each country has different standard guidelines, regulation statements, act and law to control the sperm donation program as well as different cultural or religious background. Nevertheless, we need a consensus document to operate the sperm bank with the standard guidelines to be well revised according to each country's ethical perspectives as well as contemporary scientific evolution. This article will provide what is the Korean model for ideal sperm bank with the history of sperm cryopreservation and banking, background and prerequisite for the public sperm bank operation, and also expected effects. © Korean Medical Association.

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.

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.

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.

PURPOSE:: Three-dimensional (3D) computed tomography imaging is now being used to generate 3D models for planning orthopaedic surgery, but the process remains time consuming and expensive. For chronic radial head dislocation, we have designed a graphic overlay approach that employs selected 3D computer images and widely available software to simplify the process of osteotomy site selection. METHODS:: We studied 5 patients (2 traumatic and 3 congenital) with unilateral radial head dislocation. These patients were treated with surgery based on traditional radiographs, but they also had full sets of 3D CT imaging done both before and after their surgery: these 3D CT images form the basis for this study. From the 3D CT images, each patient generated 3 sets of 3D-printed bone models: 2 copies of the preoperative condition, and 1 copy of the postoperative condition. One set of the preoperative models was then actually osteotomized and fixed in the manner suggested by our graphic technique. Arcs of rotation of the 3 sets of 3D-printed bone models were then compared. RESULTS:: Arcs of rotation of the 3 groups of bone models were significantly different, with the models osteotomized accordingly to our graphic technique having the widest arcs. CONCLUSIONS:: For chronic radial head dislocation, our graphic overlay approach simplifies the selection of the osteotomy site(s). Three-dimensional-printed bone models suggest that this approach could improve range of motion of the forearm in actual surgical practice. LEVEL OF EVIDENCE:: Level IV—therapeutic study. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

The histone variant, macroH2A1, has an important role in embryonic stem cell differentiation and tumor progression in various types of tumors. However, the regulatory roles of macroH2A1 on bladder cancer progression have not been fully elucidated. Here, we show that macroH2A1 knockdown promotes stem-like properties of bladder cancer cells. The knockdown of macroH2A1 in bladder cancer cells increased tumorigenicity, radioresistance, degeneration of reactive oxygen species, increased sphere formation capability and an increase in the proportion of side populations. We found that macroH2A1 is required for the suppression of Lin28B identified as a novel downstream target of macroH2A1 in bladder cancer. Loss of macroH2A1 expression significantly correlated with the elevated levels of Lin28B expression and subsequently inhibited the mature let-7 microRNA expression. Furthermore, the stable overexpression of Lin28B enhances the several phenotypes, including tumorigenicity and sphere-forming ability, which are induced by macroH2A1 depletion. Importantly, Lin28B expression was regulated by macroH2A1-mediated reciprocal binding of p300 and EZH2/SUV39H1. Our results suggest that Lin28B/let-7 pathway is tightly regulated by macroH2A1 and its cofactors, and have a pivotal role in the bladder tumor progression and the regulation of stem-like characteristics of bladder cancer cells.Oncogene advance online publication, 1 June 2015; doi:10.1038/onc.2015.187. © 2015 Macmillan Publishers Limited

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.

Eom J.S.,Pusan National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2011

Duplication cysts are uncommon congenital malformations that may occur anywhere throughout the alimentary tract. The stomach is an extremely rare site of occurrence. Here, we report a case of gastric duplication cyst initially presenting with a gastric submucosal tumor. A 28-year-old man complained of dyspepsia lasting 1 year and upper endoscopy revealed an ellipsoid submucosal tumor at the greater curvature of the antrum. We intended to use the injection-and-cut technique: however, after saline injection, the lesion was dented and impossible to grasp with a snare. Therefore, we decided to perform endoscopic submucosal dissection and removed the tumor without complication. Histopathology revealed a 0.6×0.6 cm-sized duplication cyst, and there has been no recurrence in 2 years.

Jeong H.Y.,Pusan National University
Geosciences Journal | Year: 2012

Non-aqueous phase liquids (NAPLs) at contaminated sites often consist of multiple organic pollutants. In this study, the solubilization behavior of multi-component NAPLs was examined for the ternary mixtures of TCE-PCE-octane, PCE-o-xylene-octane, and hexane-octane-decane in Tween 80 solutions. In the TCE-PCE-octane mixtures, the most hydrophobic octane exhibited the enhanced solubilization compared with that predicted by the ideal behavior, but the least hydrophobic TCE showed the decreased solubilization. In reference to the ideal solubilization, PCE, the intermediate hydrophobic component in the mixtures, was less solubilized in an octane-rich region but more solubilized in a TCE-rich region. Similarly, in the PCE-o-xylene-octane mixtures, the relatively hydrophobic octane was preferentially solubilized, whereas the less hydrophobic PCE and o-xylene were outcompeted. The mutual effect on the solubilization between PCE and o-xylene was not significant due to the small difference in their hydrophobicity. Compared with the preceding NAPL mixtures, the hexane-octane-decane mixtures showed the lesser extent of the nonideal solubilization behavior, which might be attributed to the proximity in the hydrophobicity and molecular structure among these components. Thus, the nonideal solubilization behavior in NAPL mixtures was largely controlled by the relative hydrophobicity among NAPL components. © 2012 The Association of Korean Geoscience Societies and Springer-Verlag Berlin Heidelberg.

Kim B.C.,Pusan National University | Tinin M.V.,Irkutsk State University
Journal of Geodesy | Year: 2011

The first-order ionospheric error is reduced in the dual-frequency Global Navigation Satellite Systems (GNSS). In this paper, the possibility of eliminating ionospheric higher-order errors in the multifrequency GNSS is explored. Since the second-order error associated with the geomagnetic field effect on the refractive index can be eliminated in dual-frequency measurements, we explore the possibility of eliminating third-order errors in triple-frequency GNSS in view of phase scintillations. A connection between the possibility of improving the multifrequency GNSS accuracy and diffraction effects in radio signal propagation through the randomly inhomogeneous ionosphere is shown. The numerical simulation has revealed that the systematic, residual ionospheric error is considerably reduced when we pass on from dual-frequency to triple-frequency measurements. The change in the residual error variance during such a transition depends however on the relationship between the inner scale of the turbulent spectrum of ionospheric irregularities and the Fresnel radius. Given the inner scale larger than the Fresnel radius, not only the systematic error, but also the standard deviation reduces when we pass on from dual-frequency to triple-frequency measurements. Otherwise, when the Fresnel radius exceeds the inner scale, the variance increases with increasing number of frequencies in use. © 2010 Springer-Verlag.

Cha K.S.,Pusan National University
Journal of Invasive Cardiology | Year: 2012

Coronary stent dislodgment is a rare but serious complication during percutaneous coronary intervention. During transradial coronary intervention, retrieval of a dislodged and deformed stent into the guiding catheter is difficult or impossible, since a small 6 Fr guiding catheter and sheath system is commonly used. I describe a new method to retrieve a dislodged and damaged stent during transradial coronary intervention. When a dislodged and unexpanded stent is not pulled back completely into the guiding catheter, the damaged stent and guiding catheter can be withdrawn together into the radial artery and retrieved successfully by radial artery cutdown and repair method.

Kim S.,Pusan National University
Water Resources Management | Year: 2016

In this paper, an integrated detection scheme is developed to simultaneously address a leakage, a partial blockage and unknown branched pipeline elements. Expressions for the pressure head and discharge for a branched pipeline system having both a leakage and a blockage are derived in frequency domain. Boundary conditions for a reservoir and a branched dead-end allow the development of impedance formulations. The condition for a pipeline junction can be addressed using either a common condition for the pressure head combined with a continuity condition of discharge or a connectivity condition for impedance. In order to consider the unsteady friction’s impact, the impedance development process studied both the impact resulting from velocity profiles with two-dimensional distributions and the impact resulting from local and convective accelerations. Impedance expressions are derived for two distinct branched pipeline systems at different abnormality conditions. Based on drived formulations describing these systems, response functions were derived in the frequency domain and their corresponding time domain representations were integrated into a meta-heuristic calibration scheme for inverse transient analysis. Using an objective function for minimization of root-mean-square-errors between the observed and computed pressures, the calibration based one impulse response can simultaneously predict locations and magnitudes of abnormalities as well as parameters for a branched pipeline. The strength of the impedance-based approach for inverse transient analysis arises mainly from its feasibility to address different conservation conditions for pressure and discharge and for combining these conditions into a unified impedance connectivity condition. © 2015, Springer Science+Business Media Dordrecht.

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.

Paik J.K.,Pusan National University
Marine Technology | Year: 2012

The pursuit of green shipping and ocean energy resource exploration are key goals for today's maritime industry. One of the most notorious accidents in maritime history was the sinking of Titanic on April 15, 1912. First, steel tends to become brittle at low temperatures. Unless human error can be minimized it is not possible to protect human health and the environment fully and to ensure safety. Human error results from ignoring human factors and ergonomics, with such ignorance either the root cause of many maritime accidents. Ignorance of the engineering factors that cause human error is due primarily to a lack of knowledge and guidance at the design, building, and operation stages. Another distinct characteristic of this ship was its double-sided hull arrangement, the aim of which was to prevent unintended water ingress into the cargo holds in the event of side shell structural failure.

Kim Y.-T.,Pusan National University
Chemistry Letters | Year: 2010

In this study, we suggest a unique approach with which it is possible to enhance the capacity and cycle performance of composite anode materials for lithium ion batteries. We introduced surface thiol groups onto mesocarbon microbeads (MCMB), and these functional groups efficiently obstructed the agglomeration between Sn nanoparticles in the composite formation. This resulted in the high dispersion of Sn nanoparticles with very small size. Half-cell tests showed that highly dispersed Sn nanoparticles enabled us to enhance the capacity by improvement of mechanical stress tolerance in the charge/discharge process. © 2010 The Chemical Society of Japan.

Kim H.-S.,Pusan National University
Molecules and Cells | Year: 2012

Human endogenous retroviruses (HERVs) mediate structural variation and genomic instability based on their multiple copy number, inherent ability to mobilize via reverse transcriptase, and high sequence similarity. Moreover, they undergo multiple amplification and retrotransposition events, resulting in the widespread distribution of complete or partial retroviral sequences throughout the primate genome. As such, HERV elements have played important biological roles in genome evolution, and their long terminal repeat (LTR) elements contain numerous regulatory sequences, including effective promoters, enhancers, polyadenylation signals, and transcription factorbinding sites. Lastly, HERV elements are capable of influencing the expression of neighboring genes, a process that also contributed to primate evolution. © 2012 KSMCB.

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.

Kysar J.W.,Columbia University | Saito Y.,Columbia University | Oztop M.S.,Columbia University | Lee D.,Pusan National University | Huh W.T.,University of British Columbia
International Journal of Plasticity | Year: 2010

A single nickel crystal is indented with a wedge indenter such that a two-dimensional deformation state with three effective plane strain slip systems is induced. The in-plane lattice rotation of the crystal lattice is measured with a three micrometer spatial resolution using Orientation Imaging Microscopy (OIM). All non-zero components of the Nye dislocation density tensor are calculated from the lattice rotation field. A rigorous analytical expression is derived for the lower bound of the total Geometrically Necessary Dislocation (GND) density. Existence and uniqueness of the lower bound are demonstrated, and the apportionment of the total GND density onto the effective individual slip systems is determined. The lower bound solution reduces to the exact solution under circumstances in which only one or two of the effective slip systems are known to have been activated. The results give insight into the active slip systems as well as the dislocation structures formed in the nickel crystal as a result of the wedge indentation. © 2010 Elsevier Ltd. All rights reserved.

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.

The purpose of this study is to examine the potential mediating role of mothers' social interactions with their infants in the association between maternal depressive symptoms (MDSs) at three time points and infants' social skills in Korea. Data were taken from 1,472 infants and mothers of the Public Study of Korean Children. Mothers completed the Kessler 6 to examine MDSs at three time points. Mothers also completed the Parenting Style Questionnaires to assess infants' social skills. Correlational analyses revealed that mothers who had depressive symptons when infants were 4 months of age were less likely to be responsive and sensitive when mothers interacted with their infants. In addition, sensitive and responsive interactions with their infants were positively correlated with infants' social skills. Structural equation model analyses showed that mothers' responsive and sensitive interactions with their infants entirely mediated the association between MDSs at 4 months' postpartum and infants' social skills. The findings suggest that the mediating role of sensitive and responsive interactions with their infants in the association betweemn MDSs and infants' social skills is potentially similar in Asian samples. © 2013 Michigan Association for Infant Mental Health.

Kim J.H.,Pusan National University
Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions | Year: 2012

We assess microvascular integrity as a marker of myocardial viability after coronary stenting, using only a pressure guidewire. Microvascular integrity generally is not assessed using pressure-only guidewires because the transducer lies upstream of microvasculature. We partially inflate a balloon inside a coronary stent to achieve a specific normalized pressure drop at rest (distal coronary/aortic pressure = 0.8) and then infuse a vasodilator, to render the wire sensitive to microvascular function. We hypothesize that the further decline in pressure (ΔFFR(0.8) ) predicts MRI myocardial viability. We studied 29 subjects with acute coronary syndrome including myocardial infarction. After successful culprit stenting, the resting coronary/aortic pressure was set to 0.8 using temporary balloon obstruction. ΔFFR(0.8) was defined as 0.8-(distal coronary/aortic pressures) during adenosine-induced hyperemia. The average transmural extent of infarction was defined as the average area of MRI late gadolinium enhancement (after 2.8 ± 1.5 days) divided by the corresponding full thickness of the gadolinium enhanced sector in short axis slices, and was compared with ΔFFR(0.8) . Results: ΔFFR(0.8) corresponded inversely and linearly with the average transmural extent of infarction (r(2) = 0.65, P < 0.001). We found that a transmural extent of infarction of 0.50 corresponded to a ΔFFR(0.8) threshold of 0.1, and had high sensitivity and specificity (100% and 94.4%, respectively). Using only an upstream pressure-sensitive guidewire and a partially obstructing balloon during pharmacologic hyperemia, we were able to predict MRI myocardial viability with high accuracy after relief of epicardial stenosis. With further validation, this may prove a useful clinical prognostic tool after percutaneous intervention. Copyright © 2011 Wiley-Liss, Inc.

Jung J.H.,Pusan National University
Korean journal of ophthalmology : KJO | Year: 2013

Here, we report an extremely rare case of acquired nasolacrimal duct obstruction caused by oncocytic carcinoma. A 64-year-old man presented to the hospital complaining of epiphora and left-side nasal obstruction. Ophthalmic and otolaryngology examination revealed a left lacrimal duct obstruction caused by a mass in the left nasal cavity and lacrimal drainage system. The mass was removed and confirmed as an oncocytic carcinoma. Nine months after surgery, without adjuvant radiotherapy, a left orbital mass was observed and the patient underwent reoperation. The mass proved to be recurrent oncocytic carcinoma. The patient underwent adjuvant radiotherapy to eradicate any residual tumor and the patient remains tumor-free one year post-radiotherapy.

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.

Lim A.R.,Jeonju University | Jeong S.-Y.,Pusan National University
Journal of Molecular Structure | Year: 2013

The ferroelectric phase transition in triglycine sulfate ((NH 2CH2COOH)3·H2SO4, TGS)) crystals, occurring at TC of 322 K, was studied using 1H and 13C CP/MAS NMR. From the spin-lattice relaxation time in the rotating frame, T1ρ, of 1H and 13C, we found that the slopes of the T1ρ versus temperature curve changed near TC. In addition, the change of intensities for the protons and carbons NMR signals in the ferroelectric and the paraelectric phases led to the noticeable changes in the environments of proton and carbon in the carboxyl groups. The carboxyl ordering was the dominant factor driving the phase transition. Our study of the 1H and 13C spectra showed that the ferroelectric phase transition of TGS is of the order-disorder type due to ordering of the carboxyl groups. © 2013 Elsevier B.V. All rights reserved.

Kang H.,Pusan National University
Journal of the Korean Astronomical Society | Year: 2013

Nonthermal radiation from supernova remnants (SNRs) provides observational evidence and constraints on the diffusive shock acceleration (DSA) hypothesis for the origins of Galactic cosmic rays (CRs). Recently it has been recognized that a variety of plasma wave-particle interactions operate at astrophysical shocks and the detailed outcomes of DSA are governed by their complex and nonlinear interrelationships. Here we calculate the energy spectra of CR protons and electrons accelerated at Type Ia SNRs, using time-dependent, DSA simulations with phenomenological models for magnetic field amplification due to CR streaming instabilities, Alfv ́enic drift, and free escape boundary. We show that, if scattering centers drift with the Alfv ́en speed in the amplified magnetic fields, the CR energy spectrum is steepened and the acceleration efficiency is significantly reduced at strong CR modified SNR shocks. Even with fast Afv ́enic drift, DSA can still be efficient enough to develop a substantial shock precursor due to CR pressure feedback and convert about 20-30% of the SN explosion energy into CRs. Since the high energy end of the CR proton spectrum is composed of the particles that are injected in the early stages, in order to predict nonthermal emissions, especially in X-ray and -ray bands, it is important to follow the time dependent evolution of the shock dynamics, CR injection process, magnetic field amplification, and particle escape. Thus it is crucial to understand the details of these plasma interactions associated with collisionless shocks in successful modeling of nonlinear DSA. © 2013 The Korean Astronomical Society. All Rights Reserved.

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.

Ahn J.K.,Pusan National University
Few-Body Systems | Year: 2013

Recent Lattice QCD calculations predict a weekly bound H-dibaryon or a resonant state near the ΛΛ threshold although definite results should be waited for with physical quark masses. We propose to search for the H-dibaryon in ΛΛ production from (K-, K+) reactions off nuclei and also for the weakly bound H-dibaryon by its weak decays to answer the long-standing question about the existence of the H-dibaryon. For this experiment, we plan to construct a large-acceptance hyperon spectrometer with a time projection chamber to detect Λ particles with a good momentum resolution. This spectrometer will also enhance the capability of hadron physics at J-PARC. © 2012 Springer-Verlag.

Kyae B.,Pusan National University | Park J.-C.,Korea Institute for Advanced Study
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

In order to significantly raise the mass of the supersymmetry Higgs boson, we consider a radiative correction to it by heavy (∼1TeV) hidden sector fields, which communicate with the Higgs through relatively light "messengers" (300-500 GeV). The messenger fields (S, S̄) are coupled to the Higgs ("y HSH uH d," y H≲0.7) and also to hidden sector fields with a Yukawa coupling of order unity. The hidden sector fields are assumed to be large representations of a hidden gauge group, and so their scalar partner masses can be heavier than other typical soft scalars in the visible sector. Even with a relatively small y H (∼0.2) or tanβ∼10 but without top-stop's considerable contributions, the radiative correction by such hidden sector fields can be enhanced enough to yield the 125 GeV Higgs mass. © 2012 American Physical Society.

Kyae B.,Pusan National University | Park J.-C.,Korea Institute for Advanced Study
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

The 130 GeV gamma-ray line based on tentative analyses on the Fermi-LAT data is hard to be understood with dark matter annihilation in the conventional framework of the MSSM. We point out that it can be nicely explained with two body decay of a scalar dark matter (φ~DM→γγ) by the dimension 6 operator suppressed with the mass of the grand unification scale (~1016GeV), L⊃|φ~DM|2FμνFμν/MGUT2, in which the scalar dark matter φ~DM develops a TeV scale vacuum expectation value. We propose a viable model explaining the 130 GeV gamma-ray line. © 2012 Elsevier B.V.

Sivakumar S.,Pusan National University
Environmental Monitoring and Assessment | Year: 2015

Earthworms are abundant and ecologically very important organisms in the soil ecosystem. Impacts by pollutants on earthworm communities greatly influence the fertility of the terrestrial environment. In ecotoxicology, earthworms are good indicators of metal pollution. The observed median lethal concentrations (LC50) and the effective concentrations that cause 50 % reduction of earthworm growth and reproduction (EC50) are referred to as toxicity concentrations or endpoints. In addition, the ‘no observed effective concentration’ (NOEC) is the estimation of the toxicity of metals on earthworms expressed as the highest concentration tested that does not show effects on growth and reproduction compared to controls. This article reviews the ecotoxicological parameters of LC50, EC50 and NOEC of a set of worms exposed to a number of metals in various tested media. In addition, this article reviews metal accumulation and the influences of soil characteristics on metal accumulation in earthworms. Morphological and behavioural responses are often used in earthworm toxicity studies. Therefore, earthworm responses due to metal toxicity are also discussed in this article. © 2015, Springer International Publishing Switzerland.

Kyae B.,Pusan National University
European Physical Journal C | Year: 2012

We consider a supersymmetric hybrid inflation model with two inflaton fields. The superpotential during inflation is dominated by W=(κS+κ′S′)M 2, where S, S′ are inflatons carrying the same U(1) R charge, κ, κ′ are dimensionless couplings, and M (~10 15-16 GeV) is a dimensionful parameter associated with a symmetry breaking scale. One light mass eigenstate drives inflation, while the other heavier mass eigenstate is stuck to the origin. The smallness of the lighter inflaton mass for the scalar spectral index n s≈0. 96, which is the center value of WMAP7, can be controlled by the ratio κ′/κ through the supergravity corrections. We also discuss the possibility of the two field inflation and large non-Gaussianity in this setup. © 2012 Springer-Verlag / Società Italiana di Fisica.

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.

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.

Kang H.,Pusan National University
Journal of Astronomy and Space Science | Year: 2013

Most of high energy cosmic rays (CRs) are thought to be produced by diffusive shock acceleration (DSA) at supernova remnants (SNRs) within the Galaxy. Fortunately, nonthermal emissions from CR protons and electrons can provide direct observational evidence for such a model and place strong constraints on the complex nonlinear plasma processes in DSA theory. In this study we calculate the energy spectra of CR protons and electrons in Type Ia SNRs, using time-dependent DSA simulations that incorporate phenomenological models for some wave-particle interactions. We demonstrate that the timedependent evolution of the self-amplified magnetic fields, Alfvénic drift, and escape of the highest energy particles affect the energy spectra of accelerated protons and electrons, and so resulting nonthermal radiation spectrum. Especially, the spectral cutoffs in X-ray and γ-ray emission spectra are regulated by the evolution of the highest energy particles, which are injected at the early phase of SNRs. Thus detailed understandings of nonlinear wave-particle interactions and time-dependent DSA simulations of SNRs are crucial in testing the SNR hypothesis for the origin of Galactic cosmic rays. © The Korean Space Science Society.

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.

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.

Woo H.Y.,Pusan National University
The Korean journal of hepatology | Year: 2011

E-cadherin is involved in intercellular binding and cellular polarity formation. Snail is a key regulator of the epithelial-mesenchymal transition and is closely associated with tumor invasiveness due to its ability to suppress E-cadherin expression. We investigated the expressions of E-cadherin and Snail in hepatocellular carcinoma (HCC) tissue to determine the clinical significance of these proteins in HCC. Immunohistochemistry was used to examine the expressions of E-cadherin and Snail in resected tissues from 59 patients diagnosed with HCC. We also evaluated the relationship between the expressions of these two molecules in HCC tissue and clinicopathologic factors in the patients. Immunohistochemistry showed that Snail was stained in 20.3% of the HCC tissues and 3.4% of noncancerous tissues. Snail was not stained in the area of E-cadherin expression. The expression of Snail in the HCC tissue was associated with poorly differentiated HCC (P=0.028). The expression of Snail without E-cadherin staining in HCC tissue was significantly associated with postoperative HCC recurrence (P=0.013). The expression of Snail in HCC tissue was associated with decreased expression of E-cadherin and poorly differentiated HCC. The expression of Snail without E-cadherin staining in HCC was associated with postoperative recurrence.

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.

Choi K.S.,Pusan National University
The International journal of oral & maxillofacial implants | Year: 2012

The objective of this study was to investigate the effects of different microthread designs and implant-abutment connection configurations of scalloped implants on stress distribution in bone using three-dimensional finite element analysis. Three different designs of scalloped implants (two different microthread designs and one without microthreads) with two different connection systems and two flat-top implants with similar connection systems were compared in a bone model that mimicked the anterior maxilla. Vertical and oblique (30-degree) loading with 100 N of force was applied to eight models. Peak stress levels and the distribution of stress were observed. The stress pattern of scalloped implants was distinctively different from that observed on flat-top implants. Scalloped implants showed peak stresses in the proximal cortical bone as well as in the buccal and palatal cortical bone, whereas flat-top implants showed peak stresses mainly in the buccal and palatal cortical bone and limited stress in the proximal bone. The scalloped implant without microthreads and a conical platform-switched connection demonstrated the lowest peak stress levels. The scalloped implant with a straight platform connection generally showed peak stress that was two to three times higher than that seen in the conical platform-switched model. Peak stress levels in scalloped implants varied with microthread designs, connection configurations, and the direction of loading. The conical platform-switched connection seemed more important for a scalloped implant than the microthread design in reducing loading stresses exerted on the surrounding bone. Scalloped implants without microthread and a with a conical platform-switched connection or closed microthreads and a conical platform-switched connection showed consistently lower buccal bone stress than the flat-top implants in areas where the bone had a sloping and scalloping shape.

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.

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.

Jones N.,University of Liverpool | Paik J.K.,Pusan National University
International Journal of Impact Engineering | Year: 2012

The perforation of aluminium alloy plates subjected to impacts characterised as low-velocity (up to about 20 m/s) and moderate-velocity (20-300 m/s, approximately) are examined in this paper, wherein recent experimental data and some empirical equations have been compared. The threshold velocity for the normal perforation of metal plates focuses on cylindrical projectiles with various shaped impact faces, principally flat. A criterion is suggested in order to distinquish between low-velocity and moderate-velocity impacts. Several new empirical equations have been developed in this paper. Recommendations are made for the use of particular empirical equations that are suitable for estimating the perforation energy of plates in the two impact velocity regimes which have been examined in this article. There is a paucity of experimental data which hinders the development of empirical equations, though surprisingly accurate predictions for perforation velocities are possible to achieve for some practical problems. Nevertheless, numerical studies are required to remove many of the restrictions on the validity of empirical equations, but these methods require a considerable amount of accurate experimental data on the dynamic material properties and failure criteria. © 2011 Elsevier Ltd. All rights reserved.

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.

Young Yun W.,Pusan National University | Nakagawa T.,Aichi Institute of Technology
Reliability Engineering and System Safety | Year: 2010

In this paper, we consider maintenance policies for products in which the economical life cycle of products is a random variable. First, we study a periodic replacement policy with minimal repair. The system is minimally repaired at failure and is replaced by new one at age T (periodic replacement policy with minimal repair of Barlow and Hunter [1]). The expected present value of total maintenance cost of products with random life cycle is obtained and the optimal replacement interval minimizing the cost is found. Second, we consider an inspection policy for products with random life cycle to detect the system failure. The expected total cost is obtained and the optimal inspection interval is found. Numerical examples are also included. © 2009 Elsevier Ltd. All rights reserved.

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.

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.

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.

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.

Lim H.-C.,Pusan National University
Physica A: Statistical Mechanics and its Applications | Year: 2012

In order to provide statistically reliable information of a wind energy site, accurate analysis on the atmospheric stability and climate characteristics in a certain area is a prerequisite. Two 2-D ultrasonic anemometers and one cup anemometer, located perpendicular to the prevailing wind direction, were used to measure the atmospheric wind environment at a height of 4.5 m in coastal region of the Wol-Ryong, Jeju, South Korea. The study is aiming to understand the atmospheric stability about a coastal region, and the effect of roughness length. We calculate the Monin-Obukhov length for division of atmospheric stability about unstable regime, neutral regime and stable regime. The distribution of diurnal Monin-Obukhov length is highly sporadic in the coastal region due to the effect of radiant heat from the surface or other environmental effects. In order to calculate the roughness length in coastal region, three different methods are applied in terms of the surface roughness, flow fluctuation and gust wind, which are called logarithmic profile, standard deviation and gust factor methods. In the study, the atmospheric stability was insignificant when applying these three methods. In the results, three different roughness length scales sufficiently showed the effect of obstacle and surface conditions around the measurement position. On the basis of an overall analysis of the short-term data measured in the Wol-Ryong area, Jeju Island, it is concluded that for the development of future wind energy resources, the Wol-Ryong site could be a good candidate for a future wind energy site. © 2012 Elsevier B.V. All rights reserved.

Park K.,Kyung Hee University | Pak Y.,Pusan National University | Kim Y.,Kyung Hee University
Journal of the American Chemical Society | Year: 2012

Type-III copper-containing enzymes have dicopper centers in their active sites and exhibit a novel capacity for activating aliphatic C-H bonds in various substrates by taking molecular oxygen. Dicopper enzyme models developed by Tolman and co-workers reveal exceptionally large kinetic isotope effects (KIEs) for the hydrogen transfer process, indicating a significant tunneling effect. In this work, we demonstrate that variational transition state theory allows accurate prediction of the KIEs and Arrhenius parameters for such model systems. This includes multidimensional tunneling based on state-of-the-art quantum-mechanical calculations of the minimum-energy path (MEP). The computational model of bis(μ-oxo)dicopper enzyme consists of 70 atoms, resulting in a 204-dimensional potential energy surface. The calculated values of E a H - E a D, A H/A D, and the KIE at 233 K are -1.86 kcal/mol, 0.51, and 28.1, respectively, for the isopropyl ligand system. These values agree very well with experimental values within the limits of experimental error. For the representative tunneling path (RTP) at 233 K, the pre- and post-tunneling configurations are 3.3 kcal/mol below the adiabatic energy maximum, where the hydrogen travels 0.54 Å by tunneling. We found that tunneling is very efficient for hydrogen transfer and that the RTP is very different from the MEP. It is mainly heavy atoms that move as the reaction proceeds from the reactant complex to the pretunneling configuration, and the hydrogen atom suddenly hops at that point. © 2012 American Chemical Society.

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.

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.

Jang J.Y.,LG Corp | Bae H.H.,LG Corp | Lee S.J.,LG Corp | Ha M.Y.,Pusan National University
Applied Energy | Year: 2013

During winter operation, an air-source heat pump extracts heat from the cold outside air and releases the heat into the living space. At certain outside air conditions, when it operates in heating mode, frost can form on the air-cooled heat exchanger, decreasing the heating performance. Conventionally, reverse-cycle defrosting (RCD) has been the common method of frost removal. But this method requires the interruption of heating during defrosting, as well as a period of time to reheat the cooled pipes of the indoor units after defrosting. In this study, a new technology called continuous heating was developed, which utilize only a hot gas bypass valve to remove the frost from the outdoor heat exchanger and thus enabling the supply of hot air to indoors without any interruption. For this, a new high temperature and low pressure gas bypass method was designed, which is differentiated from the common high pressure hot gas bypass methods by its use of low pressure. Various refrigerant mass flow distributions were examined, and the most effective defrosting mass flow was 50% in this case. Heating capacity was increased by 17% because of continuous heating, and the cumulated energy efficiency was increased by 8% compared to the traditional reverse cycle defrosting over 4. h including two defrost operations. Also, cumulated energy efficiency was increased by 27% compared to electronic heaters that supply the same heating capacity during defrosting. By this new technology, it has been proved that continuous heating and energy savings could be achieved without adopting expensive technologies. © 2013 Elsevier Ltd.

Ginsenoside, one of the active ingredients of Panax ginseng, has a variety of physiologic and pharmacologic effects. The purpose of this study was to explore the effects of ginsenoside Rd (G-Rd) on melastatin type transient receptor potential 7 (TRPM7) channels with respect to the proliferation and survival of AGS and MCF-7 cells (a gastric and a breast cancer cell line, respectively). AGS and MCF-7 cells were treated with different concentrations of G-Rd, and caspase-3 activities, mitochondrial depolarizations, and sub-G1 fractions were analyzed to determine if cell death occurred by apoptosis. In addition, human embryonic kidney (HEK) 293 cells overexpressing TRPM7 channels were used to confirm the role of TRPM7 channels. G-Rd inhibited the proliferation and survival of AGS and MCF-7 cells and enhanced caspase-3 activity, mitochondrial depolarization, and sub-G1 populations. In addition, G-Rd inhibited TRPM7-like currents in AGS and MCF-7 cells and in TRPM7 channel overexpressing HEK 293 cells, as determined by whole cell voltage-clamp recordings. Furthermore, TRPM7 overexpression in HEK 293 cells promoted G-Rd induced cell death. These findings suggest that G-Rd inhibits the proliferation and survival of gastric and breast cancer cells by inhibiting TRPM7 channel activity. © The Korean Society of Ginseng.

The reductive perturbation method is used to derive a generic form of nonlinear Schrödinger equation (NLSE) that describes the nonlinear evolution of electrostatic (ES)/electromagnetic (EM) waves in fully relativistic two-fluid plasmas. The matrix eigenvector analysis shows that there are two mutually exclusive modes of waves, each mode involving only either one of two electric potentials, A and φ. The general result is applied to the electromagnetic mode in electron-ion plasmas with relativistically high electron temperature (T e ≫m e c 2). In the limit of high frequency (ck ≫ ω e), the NLSE predicts bump type electromagnetic soliton structures having width scaling as ∼ kT e 5/2. It is shown that, in electron-positron pair plasmas with high temperature, dip type electromagnetic solitons can exist. The NLSE is also applied to electrostatic (Langmuir) wave and it is shown that dip type solitons can exist if kλ D ≪ 1, where λ D is the electron's Debye length. For the kλ D ≫ 1, however, the solution is of bump type soliton with width scaling as ∼ 1/(k 5 T e). It is also shown that dip type solitons can exist in cold plasmas having relativistically high streaming speed. © 2012 American Institute of Physics.

Kang H.,Pusan National University
Journal of the Korean Astronomical Society | Year: 2016

The Toothbrush radio relic associated with the merging cluster 1RXS J060303.3 is presumed to be produced by relativistic electrons accelerated at merger-driven shocks. Since the shock Mach number inferred from the observed radio spectral index, Mradio ≈ 2:8, is larger than that estimated from X-ray observations, MX ≲ 1.5, we consider the re-acceleration model in which a weak shock of Ms ≈ 1.2 – 1.5 sweeps through the intracluster plasma with a preshock population of relativistic electrons. We find the models with a power-law momentum spectrum with the slope, s ≈ 4:6, and the cutoff Lorentz factor γe;c ≈ 7 – 8 × 104 can reproduce reasonably well the observed profiles of radio fluxes and integrated radio spectrum of the head portion of the Toothbrush relic. This study confirms the strong connection between the ubiquitous presence of fossil relativistic plasma originated from AGNs and the shock-acceleration model of radio relics in the intracluster medium. © 2016. The Korean Astronomical Society. All rights reserved.

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.

Ann H.B.,Pusan National University | Lee H.-R.,Korea Institute of Science and Technology
Journal of the Korean Astronomical Society | Year: 2013

We analyze the spiral structure of 1725 nearby spiral galaxies with redshift less than 0.02. We use the color images provided by the Sloan Digital Sky Survey. We determine the arm classes (grand design, multiple-arm, flocculent) and the broad Hubble types (early, intermediate, late) as well as the bar types (SA, SAB, SB) by visual inspection. We find that flocculent galaxies are mostly of late Hubble type while multiple-arm galaxies are likely to be of early Hubble type. The fractional distribution of grand design galaxies is nearly constant along the Hubble type. The dependence of arm class on bar type is not as strong as that of the Hubble type. However, there is about a three times larger fraction of grand design spirals in SB galaxies than in SA galaxies, with nearly constant fractions of multiple-arm galaxies. However, if we consider the Hubble type and bar type together, grand design spirals are more frequent in early types than in late types for SA and SAB galaxies, while they are almost constant along the Hubble type for SB galaxies. There are clear correlations between spiral structures and the local background density: strongly barred, early-type, grand design spirals favor high-density regions, while non-barred, late-type, flocculent galaxies are likely to be found in low-density regions. © 2013 The Korean Astronomical Society. All Rights Reserved.

Kim J.K.,LG Corp | Jeong J.H.,Pusan National University
International Journal of Refrigeration | Year: 2014

Linear compressors are sensitive to external factors such as the ambient temperature and the supply voltage. This paper presents the dynamic response characteristics of a linear compressor to electric supplied voltage disturbances. A prototype compressor was constructed to realize both the conventional linear compressor and the inherent capacity modulated (ICM) linear compressor. The responses of the ICM linear compressor to the supplied voltage change were evaluated and compared with those of the conventional linear compressor at a condensing temperature range of 35-50 C and an evaporating temperature of -26 C. The cooling capacity ratio was varied by 4% for the ICM linear compressor and more than 20% for the conventional linear compressor at a normalized voltage change of 5%. Over a normalized voltage change of 5%, the normalized power factor of the ICM linear compressor varied by 4% to mitigate the performance variation, while that of the conventional linear compressor varied by 5% to aggravate the performance variations. These results show that conventional linear compressors cannot be used in appliances without stroke controllers. However, the ICM linear compressor without stroke controllers maintained its performance stability over a wide range of voltage disturbances. © 2013 Elsevier Ltd and IIR. All rights reserved.

A basis-based speaker adaptation technique is proposed, where basis vectors are derived using two-dimensional principal component analysis (2DPCA) and the speaker weight for the target speaker is constrained in the space of training speaker weights. During adaptation, the speaker weight that is derived in the maximum-likelihood framework is constrained by projecting the weight into the space of the weights of training speakers. In the experiments, the proposed approach shows performance improvement over the unconstrained 2DPCA-based approach.

The present paper concerns a semi-analytical procedure for moderately large deflections of an infinite non-uniform static beam resting on a nonlinear elastic foundation. To construct the procedure, we first derive a nonlinear differential equation of a Bernoulli-Euler-von Kármán "non-uniform" beam on a "nonlinear" elastic foundation, where geometrical nonlinearities due to moderately large deflection and beam non-uniformity are effectively taken into account. The nonlinear differential equation is transformed into an equivalent system of nonlinear integral equations by a canonical representation. Based on the equivalent system, we propose a method for the moderately large deflection analysis as a general approach to an infinite non-uniform beam having a variable flexural rigidity and a variable axial rigidity. The method proposed here is a functional iterative procedure, not only fairly simple but straightforward to apply. Here, a parameter, called a base point of the method, is also newly introduced, which controls its convergence rate. An illustrative example is presented to investigate the validity of the method, which shows that just a few iterations are only demanded for a reasonable solution. © 2014 Springer-Verlag Wien.

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.

Jeong J.H.,Pusan National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2012

A 49-year-old female was admitted to our hospital for acute pancreatitis. The abdomen CT scan incidentally showed midline liver with hepatomegaly, centrally located gallbladder, pancreas truncation, right sided small bowel, left sided large bowel, interruption of the inferior vena cava with azygos continuation, preduodenal portal vein, and multiple spleens in the left upper quadrant. In MRCP, the head of pancreas was enlarged and short main pancreatic duct without accessory duct was showed. EUS revealed enlarged ventral pancreas with a main pancreatic duct of normal caliber, absence of the accessory pancreatic duct and the dorsal pancreas. She was diagnosed as polysplenia syndrome with agenesis of dorsal pancreas. It is a rare congenital anomaly frequently associated with various visceral anomalies including multiple spleens, impaired visceral lateralization, congenital heart diseases, gastrointestinal abnormalities and azygos continuation of the inferior vena cava. We report a case of polysplenia syndrome with agenesis of dorsal pancreas presenting acute pancreatitis.

Gill W.,Pusan National University
International Journal of Modern Physics C | Year: 2011

This study examines the dependence of crossing time on sequence length for a finite population in an asymmetric multiplicative, or additive, landscape with a positive asymmetric parameter and a fixed extension parameter in three types of mutation-selection model: the coupled discrete-time model, the coupled continuous-time model, and the decoupled continuous-time model. The crossing times for a finite population in the three types of mutation-selection model began to deviate from the crossing times for an infinite population at a critical sequence length. It then increased exponentially as a function of sequence length in the stochastic region where the sequence length was much longer than the critical sequence length. The exponentially increasing rates of the crossing times in the three types of mutation-selection model were similar to each other. These rates were decreased by increasing the asymmetric parameter. Once the asymmetric parameter reached a certain limit the crossing times for the three models in the stochastic region could not be decreased further by increasing the asymmetric parameter past this limit. © 2011 World Scientific Publishing Company.

Ha T.G.,Pusan National University
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2016

In this paper, we consider the viscoelastic wave equation with Balakrishnan–Taylor damping. This work is devoted to prove uniform decay rates of the energy without imposing any restrictive growth assumption on the damping term and weakening the usual assumptions on the relaxation function. Our estimate depends both on the behavior of the damping term near zero and on behavior of the relaxation function at infinity. © 2016, Springer International Publishing.

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).

Kim C.-G.,Pusan National University
Computers and Mathematics with Applications | Year: 2011

In this study, using fixed point index theorems and monotone iterative techniques, we present iterative schemes as well as the existence of positive solutions to the m-point boundary value problem on a half-line. © 2011 Elsevier Ltd. All rights reserved.

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.

The stems with hook of Uncaria rhynchophylla have been used in traditional medicine as an antipyretic, antihypertensive, and anticonvulsant in China and Korea. In this study, we investigated the mechanism responsible for anti-inflammatory effects of U. rhynchophylla in RAW 264.7 macrophages. The aqueous extract of U. rhynchophylla inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) and interleukin (IL)-1β secretion as well as inducible NO synthase (iNOS) expression, without affecting cell viability. Furthermore, U. rhynchophylla suppressed LPS-induced nuclear factor κB (NF-κB) activation, phosphorylation, and degradation of inhibitory protein IκB (IκB)-α, phosphorylation of Akt, extracellular signal-regulated kinase 1/2, p38 kinase, and c-Jun N-terminal kinase. These results suggest that U. rhynchophylla has the inhibitory effects on LPS-induced NO and IL-1β production in macrophages through blockade in the phosphorylation of Akt and mitogen-activated protein kinases, following IκB-α degradation and NF-κB activation.

Choi S.,Pusan National University | Cho Y.I.,Arizona State University
School Psychology International | Year: 2013

This study investigated the associations of psychological and social variables with the likelihood of exhibiting three different behaviors as a bystander in a bullying situation. The sample comprised 238 Korean-American and Korean students, from the 3rd to 12th grades, studying in the USA. Students receiving classmate support showed a lower probability of exhibiting outsider behaviors in a bullying situation as compared to non-involvers, whereas those receiving teacher support showed less likelihood of exhibiting assistant, outsider, and defender behaviors as compared to non-involvers. Furthermore, students showing higher responsibility exhibited a lower probability of being a defender group as compared to the non-involvers, while those showing higher empathy demonstrated a greater probability of being in the defender group over non-involvers. The current study discusses the implications for bullying preventive interventions in school settings. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Sohn K.T.,Pusan National University
Advances in Atmospheric Sciences | Year: 2013

This study aimed to develop the seasonal forecast models of Korean dust days over South Korea in the springtime. Forecast mode was a ternary forecast (below normal, normal, above normal) which was classified based on the mean and the standard deviation of Korean dust days for a period of 30 years (1981-2010). In this study, we used three kinds of monthly data: the Korean dust days observed in South Korea, the National Center for Environmental Prediction in National Center for Atmospheric Research (NCEP/NCAR) reanalysis data for meteorological factors over source regions of Asian dust, and the large-scale climate indices offered from the Climate Diagnostic Center and Climate Prediction Center in NOAA. Forecast guidance consisted of two components; ordinal logistic regression model to generate trinomial distributions, and conversion algorithm to generate ternary forecast by two thresholds. Forecast guidance was proposed for each month separately and its predictability was evaluated based on skill scores. © 2013 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

Hwang B.-H.,Pusan National University | Hwang B.-H.,Stanford University
International Geology Review | Year: 2011

Late Cretaceous calc-alkaline granites in the Gyeongsang Basin evolved through the mixing of mafic and felsic magmas. The host granites contain numerous mafic magmatic/microgranular enclaves of various shapes and sizes. New SHRIMP-RG zircon U-Pb ages of both granite and mafic magmatic/microgranular enclaves are 75.0 ± 0.5 Ma and 74.9 ±0.6 Ma, respectively, suggesting that they crystallized contemporaneously after magma mixing. The time of injection of mafic melt into the felsic magma chamber can be recognized as approximately 75 Ma by field relations, petrographic features, geochemical evolution, and SHRIMP-RG zircon dating. This Late Cretaceous magma mixing event in the Korean Peninsula was probably related to the onset of subduction of the Izanagi (Kula)-Pacific ridge. © 2011 Taylor & Francis.