Chinju, South Korea
Chinju, South Korea

Gyeongsang National University is a national university governed under the ministry of education of Republic of Korea government and located in Jinju, South Gyeongsang Province and represents the South Gyeongsang Province of South Korea as one of 10 Flagship Korean National Universities along with Cheju National University, Chonbuk National University, Chonnam National University, Chungnam National University, Chungbuk National University, Kangwon National University, Kyungpook National University, Pusan National University, and Seoul National University.Gyoengsang National University has twelve colleges including arts, social science, natural science, engineering, agriculture and life science, management, veterinary, education, nursing, and medicine and eight graduate schools including medicine and public health, business administration, education, aerospace, industry etc. Other institutions with the university are the university library, the university museum, student center, university newspaper and broadcasting center, publishing company, institute for education of science talented, Korean language cultural center and so on. The current statistics of Gyeongsang National University shows that it has 1,681 academic staffs including 808 full-time professors, 361 administrative staffs and 24,502 students including undergraduate and graduate students enrolled. The university has three campuses and two of these are located in Jinju, South Gyeongsang Province and the other is located in Tongyeong. The main campus is located at Gajwa in the city of Jinju, Chilam campus, Jinju has the college of medicine, and Tongyeong campus, an hour from Jinju by car, has the college of Marine Science.The motto of Gyeongsang National University is Pioneer and it states that the eyes of pioneers see far beyond the present to the future. The history of the university begun as Jinju Agricultural College founded in Jinju in 1948, in 1968, accredited as national college and in 1972, renamed as Gyeongsang National College. In 1980, it was accredited as national university by the ministry of education and renamed as Gyeongsang National University. For more than 60 years since its foundation, Gyeongsang National University has been educating talented students who have served not only for local community but also for national prosperity by leading them to be bigger asset in many places such as communities, industries, businesses and so on around the country and the world.Gyeongsang National University is well known for many achievements in applied life science along with biochemistry, agricultural science, and veterinary. One of these is that the researchers at the university discovered a way to make cloned Turkish Angora cats glow red when exposed to ultraviolet light in 2007 and many alumni in these fields are working as researchers and professionals in research institutions and universities around the world. In present, the university has made its highly competitive fields of study broad to mechanical and aerospace systems engineering and new nano-materials engineering. In addition, Gyeongsang National University has made achievements in humanities and in sociology, two fields which lay the foundation for human ethics. Beside this, Gyeongsang National University is proud to have the college of Education in where great middle school teachers are educated to take responsibility for education of Republic of Korea, the college of Veterinary Medicine in where international veterinarians are trained, and the College of Marine Science to pioneer the studies of the ocean in the twenty first century. The university keeps moving on to provide advanced international education in Republic of Korea by successfully partnering in international campuses in Incheon as well as Busan-Jinhae Free Economic Zones.The Graduate School of Medicine and Public Health at Gyeongsang National University is unique medical training and research institution in South Gyeongsang Province and plans are being made with Gyeongsang National University Hospital to open a specialized medical center in the city of Changwon as the second Gyeongsang National University hospital in 2013. Gyeongsang National University Hospital opened with 419 beds in 1987 as the university hospital of Gyeongsang National University and is located next to the college of medicine in Chilam campus and has provided health care service with quality for more than 25 years and grown to a general and multispecialty medical hospital with 950 beds operating with specialty centers such as the local cancer center opened as the first local cancer center of its kinds in the country and rheumatoid arthritis center. Wikipedia.

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The present invention relates to a device for imaging and diagnosing the condition of obstruction of the upper airway, which can image the condition of a change in the upper airway of an OSAS patient occurring during natural sleep by using EIT and can extract information required for diagnosis. The device for imaging and diagnosing the condition of obstruction of the upper airway by using EIT according to the present invention does not require high costs, enables repeated examination to be conducted without the risk of exposure to radioactive rays, and enables examination to be performed over a prolonged period of time in an actual natural sleep state, thereby accurately diagnosing the condition of obstruction of the upper airway.

Samsung and Gyeongsang National University | Date: 2016-09-12

An organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode, the organic layer including an emission layer, wherein the organic layer includes at least one condensed cyclic compound of Formula 1: An organic light-emitting device including the condensed cyclic compound according to embodiments of the present disclosure may have low driving voltage, high efficiency, high luminance, and long lifespan.

The present invention relates to a device for imaging and diagnosing the condition of obstruction of the upper airway, which can image the condition of a change in the upper airway of an OSAS patient occurring during natural sleep by using EIT and can extract information required for diagnosis. The device for imaging and diagnosing the condition of obstruction of the upper airway by using EIT according to the present invention does not require high costs, enables repeated examination to be conducted without the risk of exposure to radioactive rays, and enables examination to be performed over a prolonged period of time in an actual natural sleep state, thereby accurately diagnosing the condition of obstruction of the upper airway.

Kang B.-G.,Gyeongsang National University | Chung S.-K.,Gyeongsang National University | Song Y.,Korea Institute of Energy Research
8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia | Year: 2011

A new active clamped three-phase isolated boost converter is proposed for low voltage distributed energy resources. The proposed converter has a parallel input and voltage doubler output structure to obtain the high output voltage from the low voltage source. The three-phase parallel input structure with an interleaved operation provides a high power rating and reduced input current ripple. The high voltage conversion ratio can be easily obtained using the voltage doubler output stage. Moreover, the zero voltage switching (ZVS) is also achieved using an active clamping circuit. The converter operation and prototype design are presented. The experimental results are finally provided to show the validity of the proposed converter scheme. © 2011 IEEE.

Chung W.S.,Gyeongsang National University | Hassanabadi H.,Shahrood University of Technology
International Journal of Theoretical Physics | Year: 2017

In this paper the deformed boson algebra giving the Gentile distribution function is constructed by using the model of ideal gas of deformed bosons and some properties of a root of unity. As an example we discuss the quantum optical problem related to the Gentile (or f-deformed) boson algebra with large but finite M. For this algebra we construct the Gentile (or f-deformed) coherent state and discuss its nonclassical properties such as sub-Poissonian statistics and anti-bunching effect. © 2017 Springer Science+Business Media New York

QIN X.,University of Electronic Science and Technology of China | CHO S.Y.,Gyeongsang National University
Acta Mathematica Scientia | Year: 2017

In this article, fixed points of generalized asymptotically quasi-ϕ-nonexpansive mappings and equilibrium problems are investigated based on a monotone projection algorithm. Strong convergence theorems are established without the aid of compactness in the framework of reflexive Banach spaces. © 2017 Wuhan Institute of Physics and Mathematics

Lee T.,Gyeongsang National University | Park T.,Gyeongsang National University
Journal of Hydrology | Year: 2017

It is critical to downscale temporally coarse GCM or RCM outputs (e.g., monthly or daily) to fine time scales, such as sub-daily or hourly. Recently, a temporal downscaling model employing a nonparametric framework (NTD) with k-nearest resampling and a genetic algorithm has been developed to preserve key statistics as well as the diurnal cycle. However, this model's usage can be limited in estimating precipitation for design storms or floods because the key statistics of annual maximum precipitation (AMP), especially for longer hourly durations, present a systematic bias that cannot be preserved due to the discontinuity of multiday consecutive precipitation events in the downscaling procedure. In the current study, we develop an approach to downscale a consecutive daily precipitation at once focusing on the reproduction of AMP totals for different durations instead of day-by-day downscaling. The proposed model has been verified with the precipitation datasets for the 60 stations across South Korea over the period 1979–2005. Additionally, two validation studies were performed with the recent datasets of 2006–2014 and nearest neighbor stations. The verification and the two validation tests conclude that the population-based NTD (PNTD) model proposed in the current study is superior to the existing NTD model in preserving the key statistics of the observed AMP series and suitable for downscaling future climate scenarios. © 2017 Elsevier B.V.

Haque M.N.,Gyeongsang National University | Kwon S.,Gyeongsang National University
Environmental Engineering Research | Year: 2017

Chlorination has been the most common antifouling method, but alternatives are under searching. In this article, we report how the hydrogen peroxide could enhance the effect of chlorination to prevent fouling by inhibiting larvae settlement and abatement of mussel colonization or by extinct of them; through marine mussel Mytilus edulis. The addition of hydrogen peroxide shows synergic effect on the veliger larvae (up to 19 folds) and effectively reduces required time of mussel mortality by 8-22%. For resolution of micro- and macro-fouling caused by the marine mussel, as well as diminishing of time and conventional chlorine dose could be important factor in favour of environment and economics. © 2017 Korean Society of Environmental Engineers.

Cho J.,YiYeon HanOk Ltd. | Lee B.,Gyeongsang National University | Yoon J.,Gyeongsang National University
WCTE 2016 - World Conference on Timber Engineering | Year: 2016

The purpose of this study is to develop a building information modelling (BIM) design process for Korean traditional wooden construction (HanOk). Member design information and parametric libraries have been derived from the BIM design procedure. The design created through this developed process is examined using the libraries for HanOk construction.

Shin S.,Hill Engineering Co. | Lee B.,Gyeongsang National University | Yoon J.,Gyeongsang National University
WCTE 2016 - World Conference on Timber Engineering | Year: 2016

The purpose of this study is to develop a seismic capacity evaluation technique for traditional wooden structures in Korea (HanOk). The shape information is derived from a BIM design procedure. The joint stiffness DB for the lateral direction of a HanOk is determined from the test results of 1/5 scale model building. A modified DDD method to build a HanOk, based on a seismic design procedure of the NEESWood report, is proposed.

Islam S.M.A.,Patuakhali Science and Technology University | Yeasmin S.,Gyeongsang National University | Islam M.S.,Patuakhali Science and Technology University
Ecotoxicology and Environmental Safety | Year: 2017

The binding affinity of organophosphate hydrolase enzyme (OphB) with soil particles in relation to the isoelectric point (pI) was studied. Immobilization of OphB with soil particles was observed by confocal microscopy, Fourier transform infrared spectroscopy (FT-IR), and Atomic force microscopy (AFM). The calculated pI of OphB enzyme was increased from 8.69 to 8.89, 9.04 and 9.16 by the single, double and triple mutant of OphB enzyme, respectively through the replacement of negatively charged aspartate with positively charged histidine. Practically, the binding affinity was increased to 5.30%, 11.50%, and 16.80% for single, double and triple mutants, respectively. In contrast, enzyme activity of OphB did not change by the mutation of the enzyme. On the other hand, adhesion forces were gradually increased for wild type OphB enzyme (90 pN) to 96, 100 and 104 pN for single, double and triple mutants of OphB enzyme, respectively. There was an increasing trend of binding affinity and adhesion force by the increase of isoelectric point (pI) of OphB enzyme. © 2017 Elsevier Inc.

Kim Y.,Gyeongsang National University | Kwon K.-Y.,Gyeongsang National University
Applied Chemistry for Engineering | Year: 2016

Four different hydroxyapatites (HAP) were prepared by a solvothermal method under different pHs and solvent species. The synthesized hydroxyapatites were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Four HAPs exhibited similar XRD patterns regardless of synthetic conditions. However, the morphology of hydroxyapatites was dependent of pH and solvent species under synthetic condition. The HAP prepared in pH 12 showed an elongated shape along the [001] direction compared to that prepared in pH 8. Also, the morphology of the HAPs synthesized in the presence of methanol and ethanol exhibited the more elongated hexagonal rod shape along the [001] direction with the high aspect ratio. © 2016, Korean Society of Industrial Engineering Chemistry. All rights reserved.

Song S.-Z.,Jeju National University | Bordbar H.,Shahid Bahonar University of Kerman | Jun Y.B.,Gyeongsang National University
Journal of Intelligent and Fuzzy Systems | Year: 2017

The concept of hesitant union (∪) is introduced. Using this, the notions of ∪-hesitant fuzzy subalgebras and ∪-hesitant fuzzy ideals are introduced and several properties are investigated. Relations between ∪-hesitant fuzzy subalgebras (resp. ideals) and ∪-hesitant fuzzy subalgebras (resp. ideals) are considered. Relations between a ∪-hesitant fuzzy subalgebra/ideal and its lower level set are investigated. Characterizations of ∪-hesitant fuzzy subalgebras/ideals are discussed. Given a subalgebra (resp., ideal) A of a BCK/BCI-algebra X, a ∪-hesitant fuzzy subalgebra (resp., ideal) is established. © 2017 IOS Press and the authors. All rights reserved.

Choi H.,Gyeongsang National University
Surgical Laparoscopy, Endoscopy and Percutaneous Techniques | Year: 2017

INTRODUCTION:: Laparoscopic liver resection has become important procedure for malignant liver disease. In this report, we describe the relevant technical maneuvers and perioperative outcomes in laparoscopic anatomic segment 6 liver resection using the Glissonian approach. PATIENTS AND METHODS:: From March 2003 and October 2015, 7 patients who diagnosed hepatocellular carcinoma had undergone laparoscopic anatomic segment 6 liver resection at the single institution. We performed retrospective analysis of the clinical and perioperative outcomes of these patients. RESULTS:: All patients were men with mean age of 62.3 years (range, 49 to 73 y). The mean operation time was 352.8 minutes (range, 180 to 435 min) and there was no case of open conversion. The mean estimated blood loss was 521.4 mL (range, 200 to 800 mL) and intraoperative transfusion needed in 1 patient. There was no postoperative morbidity and mortality. The mean postoperative hospital stay was 7.5 days (range, 5 to 12 d). All patients obtained negative resection margins. There was no patient had developed tumor recurrence during a median follow-up period of 43 months (range, 7 to 60.7 mo). CONCLUSIONS:: Laparoscopic anatomic segment 6 liver resection is a feasible operative procedure, being possible even in patients with limited liver function. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.

Nguyen K.-H.,Gyeongsang National University | Ju H.-W.,Gyeongsang National University | Truong V.-H.,Gyeongsang National University | Kweon J.-H.,Gyeongsang National University
Composite Structures | Year: 2017

Corners of composite curved beams can easily experience delamination under opening or closing bending moments. Existing literature on the delamination of curved laminated beams, however, is limited to unidirectional and cross-ply laminates with 0° and 90° layers and two-dimensional (2D) plane strain finite element analysis. This study experimentally and analytically investigates the failure behaviors of curved composite structures under four-point bending. Multiangle laminates manufactured using an out-of-autoclave prepreg were examined. A three-dimensional (3D) finite element model was created and analyzed with cohesive elements at the interfaces of adjacent plies. In the experiments, delamination dominated the failure of the curved laminates with several opening cracks. Multiple delamination positions were predicted in the analyses. Double cantilever beam specimens were tested and analyzed for a reference point for selecting cohesive parameters. Several cohesive parameters were selected and discussed. Predicted failure loads matched the experimental results well with 5.8% error when the model simulated a sufficient number of factors of the real test. © 2017 Elsevier Ltd.

Byun J.-H.,Gyeongsang National University | Park H.,Gyeongsang National University | Kim S.,Gyeongsang National University
Japanese Journal of Infectious Diseases | Year: 2017

Although Shewanella algae has been known to have weak pathogenicity, case reports on infections with this species have been steadily increasing. S. algae and S. haliotis are difficult to distinguish from each other with conventional phenotypic methods. We reviewed the microbiological and clinical features of S. algae and S. haliotis infections at our institute. Bacterial culture and identification reports from patient samples from 2010 to 2014 were reviewed to screen the cases of Shewanella infections. In addition to conventional biochemical tests, 16S rRNA gene sequence analysis and matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were performed for 19 stored bacterial isolates. Medical records were reviewed for clinical characteristics and laboratory findings. All isolates were identified as S. algae by using VITEK 2. MALDI-TOF also identified all isolates as S. algae with a 99.9 confidence value. In contrast, 16S rRNA analysis identified 10 isolates as S. algae and 9 isolates as S. haliotis. Both S. algae (60%) and S. haliotis (77%) infections were strongly associated with diseases of the hepatobiliary tract and pancreas. To distinguish between S. algae and S. haliotis, 16S rRNA gene sequence analysis seems more accurate than biochemical tests or MALDI-TOF. Patients with underlying diseases in the hepatobiliary tract and pancreas seem to be susceptible to these marine pathogens. © 2017, National Institute of Health. All Rights Reserved.

Bae I.-G.,Gyeongsang National University
Journal of the Korean Medical Association | Year: 2017

Cholera is an acute secretory form of diarrhea caused by a potent enterotoxin (cholera toxin) after ingestion of toxigenic Vibrio cholerae of the O1 or O139 serogroups. Although cholera is very common in Africa and Asia as a whole, the incidence of cholera has been very low in recent years in Korea. Dehydration and electrolyte abnormalities due to massive watery diarrhea can lead to death, and the mortality rates in untreated patients with severe cholera can exceed 70%. Effective rehydration therapy is the cornerstone of the management of patients with cholera and can reduce the mortality rate to less than 0.2%. Antibiotics reduce the volume and duration of diarrhea, but are recommended for patients with severe disease because of the rapid emergence and spread of multidrug-resistant V. cholerae across the globe. Two oral cholera vaccines are available, and the World Health Organization recommends that these oral vaccines be considered in integrated prevention programs in endemic countries at risk for outbreaks. © copy Korean Medical Association.

Lee T.,Gyeongsang National University
Geoscientific Model Development | Year: 2017

The outputs from general circulation models (GCMs) provide useful information about the rate and magnitude of future climate change. The temperature variable is more reliable than other variables in GCM outputs. However, hydrological variables (e.g., precipitation) from GCM outputs for future climate change possess an uncertainty that is too high for practical use. Therefore, a method called intentionally biased bootstrapping (IBB), which simulates the increase of the temperature variable by a certain level as ascertained from observed global warming data, is proposed. In addition, precipitation data were resampled by employing a block-wise sampling technique associated with the temperature simulation. In summary, a warming temperature scenario is simulated, along with the corresponding precipitation values whose time indices are the same as those of the simulated warming temperature scenario. The proposed method was validated with annual precipitation data by truncating the recent years of the record. The proposed model was also employed to assess the future changes in seasonal precipitation in South Korea within a global warming scenario as well as in weekly timescales. The results illustrate that the proposed method is a good alternative for assessing the variation of hydrological variables such as precipitation under the warming condition. © Author(s) 2017.

Lee T.,Gyeongsang National University | Ouarda T.B.M.J.,Masdar Institute of Science and Technology | Ouarda T.B.M.J.,National Institute for Scientific Research | Yoon S.,Climate Center
Climate Dynamics | Year: 2017

Climate change frequently causes highly nonlinear and irregular behaviors in hydroclimatic systems. The stochastic simulation of hydroclimatic variables reproduces such irregular behaviors and is beneficial for assessing their impact on other regimes. The objective of the current study is to propose a novel method, a k-nearest neighbor (KNN) based on the local linear regression method (KLR), to reproduce nonlinear and heteroscedastic relations in hydroclimatic variables. The proposed model was validated with a nonlinear, heteroscedastic, lag-1 time dependent test function. The validation results of the test function show that the key statistics, nonlinear dependence, and heteroscedascity of the test data are reproduced well by the KLR model. In contrast, a traditional resampling technique, KNN resampling (KNNR), shows some biases with respect to key statistics, such as the variance and lag-1 correlation. Furthermore, the proposed KLR model was used to simulate the annual minimum of the consecutive 7-day average daily mean flow (Min7D) of the Romaine River, Quebec. The observed and extended North Atlantic Oscillation (NAO) index is incorporated into the model. The case study results of the observed period illustrate that the KLR model sufficiently reproduced key statistics and the nonlinear heteroscedasticity relation. For the future period, a lower mean is observed, which indicates that drier conditions other than normal might be expected in the next decade in the Romaine River. Overall, it is concluded that the KLR model can be a good alternative for simulating irregular and nonlinear behaviors in hydroclimatic variables. © 2017 Springer-Verlag Berlin Heidelberg

Kim S.-J.,Gyeongsang National University
International Journal of Simulation Modelling | Year: 2016

A smart mould machining system, which detects machining status and controls the CNC through pre-simulation and real-time data, was developed. Pre-simulation predicts cutting forces, and inserts the best feed rate and virtual load on each line of the NC data. The active feed rate reduced machining by up to 36 %, without increasing the maximum cutting forces. The actual cutting load was computed from spindle load data and a friction load compensation algorithm. Collision and tool wear were detected by comparing the actual and virtual load, with the time synchronised by using tool position data. The system machined an automotive grill mould cavity for 34 hours without the supervision of a worker, because pre-simulation had stabilized the milling process and monitoring would have stopped the process if the actual load was different to the virtual load. Pre-simulation has been verified by thousands of mould makers and integrated with sensorless monitoring in an open CNC. © 2016, Vienna University of Technology. All rights reserved.

Ha H.-Y.,Korea Institute of Materials Science | Lee C.-H.,Korea Institute of Materials Science | Lee T.-H.,Korea Institute of Materials Science | Kim S.,Gyeongsang National University
Materials | Year: 2017

Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis. © 2017 by the authors.

Kim S.H.,Gyeongsang National University | Lee S.J.,Kangwon National University | Sung D.K.,KAIST
2016 International Conference on Information and Communication Technology Convergence, ICTC 2016 | Year: 2016

We propose two rate selection methods in wireless multicast systems where an incremental redundancy type hybrid automatic repeat request (HARQ-IR) scheme is employed under Rayleigh block-fading channels. We aim at maximizing the long-Term average transmission rate (LATR) while the maximum number of retransmissions is limited to L-1 and the probability that at least one user fails to decode a message within L (re)transmissions is limited to e. This problem is non-convex and involves complicated integral expressions. To reduce the computational load, we formulate a simplified problem with approximated utility and constraint functions by using the Gaussian approximation. © 2016 IEEE.

Kim H.-J.,Gyeongsang National University | Ha O.-K.,Gyeongsang National University | Jun Y.-K.,Gyeongsang National University
30th Congress of the International Council of the Aeronautical Sciences, ICAS 2016 | Year: 2016

Data Distribution Service (DDS) is a dependable communication middleware for airborne software architecture to provide real-time interoperable data exchanges. It is important to efficiently detect general message races for debugging DDS programs, because it is the most serious type of software faults and the presence of general message races in the programs has not been reported. This paper present an experimental fault case to prove the presence of general message races in DDS programs for airborne software.

Raj L.P.,Gyeongsang National University | Myong R.S.,Gyeongsang National University
30th Congress of the International Council of the Aeronautical Sciences, ICAS 2016 | Year: 2016

In this study, a computational method for describ ing water droplet impingement around a multi-element high-lift airfoil consisting of a slat, main and flap elements is presented. The scheme is developed on the basis of a multidimensional unstructured second-order positivity-preserving finite volume upwind method. For the droplet impingement model, the shallow water type droplet model is used as the basic building b lock for the numerical solver of air-mixed droplet flow. Furthermore, droplet splashing, bouncing, and deformation models were used to take into account the effects of large droplet dynamics on the impingement results. The comparison of the collection efficiency for a multi-element airfoil with experimental result shows good agreement.

Kim Y.,Gyeongsang National University | Seo G.,Gyeongsang National University
30th Congress of the International Council of the Aeronautical Sciences, ICAS 2016 | Year: 2016

A classical controller can be designed for a stable single vehicle to guarantee a certain stability margin. For aerospace applications, the stability margin is an important measure whose desirable values are explicitly found in military specifications such as MIL-STL-1797. It is well-known that a LQR (linear quadratic regulator) control-based vehicle has a guaranteed stability margin of 6 dB (gain margin) and 60 degrees (phase margin), and it thus has a desired stability margin according to MIL-STL-1797. Here, the LQR control 'u' is given as a state feedback control, i.e. u = Fx, where 'F' is a LQR gain and 'x' is the state vector. But then, what will happen to the guaranteed stability margin if multiple LQR control-based vehicles are connected according to a certain network topology for some purpose such as formation flight? For the purpose of formation flight, the same LQR control gain as for a single aircraft can be used but multiplied with the relative state vector being calculated based on each aircraft's neighbours; the LQR control u this time is given as u = FL(x-h), where 'F' is the same LQR gain as before, 'L' is an augmented version of the Laplacian matrix corresponding to the network topology, and 'h' is a desired state vector. In this case, it can be shown that (1) the stability margin after the interconnection cannot exceed the guaranteed stability margin of LQR control before the interconnection; (2) when each of the vehicles has a single integrator, the stability margin becomes the Laplacian matrix's zero eigenvalue sensitivity's inverse with a high chance when the sensitivity is large; and (3) there exists a computationally effective upper bound that estimates the stability margin to high accuracy. In addition, a generalized Laplacian matrix (still reflecting the network topology) can be designed for a (not necessarily symmetric) directed network, in a way to maximize the stability margin of the networked system via a LMI (linear matrix inequality) technique.

Chang J.Y.,Gyeongsang National University | Jung S.,Gyeongsang National University | Park H.,Gyeongsang National University | Han M.-K.,Seoul National University
PLoS ONE | Year: 2017

Objective We investigated the association between the presence of major vessel occlusion (MVO) and the intensity of the International Normalized Ratio (INR) in cardioembolic high-risk patients taking warfarin. We also evaluated whether the presence of MVO could predict the subtherapeutic range of INR ≤1.7 ensuring safe administration of intravenous thrombolytics. Methods The medical records of 177 cardioembolic stroke patients who were taking warfarin between April, 2008 and March, 2015 were retrospectively analyzed. Logistic regression analysis was performed to calculate the odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between vessel occlusion and intensity of INR. To predict INR ≤1.7, decision tree analysis was performed. Results INR was inversely associated with MVO in an unadjusted model (OR, 0.36; 95% CI, 0.17-0.76), and in a model adjusted for initial NIHSS score and time from symptom onset to arrival (OR, 0.28; 95% CI, 0.11-0.73). Fifty-two of 58 (89.7%) patients with MVO had an INR ≤1.7, compared with 83 of 119 (69.7%) patients without MVO. Indication for anticoagulation agent use was dichotomized into NVAF and others, and applied to the subgroup of patients with MVO. All patients with NVAF (31/31, 100%) had INR ≤1.7, while 21 of 27 of the other patients (77.8%) had INR ≤1.7. Conclusions Low INR at presentation in cardioembolic stroke patients during anticoagulation treatment was associated with occurrence of major vessel occlusive stroke. Presence of MVO and indications for anticoagulation may be utilized to ensure the feasibility of administration of intravenous thrombolytics. © 2017 Chang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Wang C.,Soochow University of China | Pfleger B.F.,University of Wisconsin - Madison | Kim S.-W.,Gyeongsang National University
Current Opinion in Biotechnology | Year: 2017

Via metabolic engineering, industrial microorganisms have the potential to convert renewable substrates into a wide range of biofuels that can address energy security and environmental challenges associated with current fossil fuels. The user-friendly bacterium, Escherichia coli, remains one of the most frequently used hosts for demonstrating production of biofuel candidates including alcohol-, fatty acid- and terpenoid-based biofuels. In this review, we summarize the metabolic pathways for synthesis of these biofuels and assess enabling technologies that assist in regulating biofuel synthesis pathways and rapidly assembling novel E. coli strains. These advances maintain E. coli's position as a prominent host for developing cell factories for biofuel production. © 2017 Elsevier Ltd

Murugesan R.,Gyeongsang National University | Park J.H.,Gyeongsang National University
Journal of Mechanical Science and Technology | Year: 2017

Recent rapid development of single molecule analysis highly demands the trapping of molecular objects. In this study, we present how stability and random motions vary depending on dielectrophoretic and electrophoretic descriptions for a molecular object in planar quadrupole electrical traps. The object is modeled as a molecular dipole surrounded by a cavity (“molecular dipole cavity”) to introduce the solvent accessible surface of a solute molecule, and the instantaneous electrophoretic and dielectrophoretic force formulations are employed for the rigorous estimation of the deterministic stability which is identified by the equation of motion without random impulse and the random fluctuation that is compared with the trap size for the identification of random stability. The deterministic stability is analyzed with the universal Mathieu equation based theories for Paul trap while the random fluctuation is computed by averaging the multiple trajectories with different random seeds. The results show that the deterministic stabilities are quite similar in dielectrophoretic and electrophoretic descriptions, whereas the random fluctuation is significantly influenced by the type of force description. This study is expected to provide fundamental information in designing a quadrupole trap for molecular objects which is essential in single molecule analysis. © 2017, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

Bagchi S.,Gyeongsang National University
Journal of Computer Science | Year: 2017

Traditionally, the concepts of graph theory are applied to design stationary computer networks and, to analyze dynamics of social networks. However, the majority of non-stationary network models are formulated by using Ordinary Differential Equations (ODE) with varying orders having homogeneous or non-homogeneous forms. However, the analysis of continuous solution spaces of ODE and understanding of the interplay of spaces in complex systems are difficult to formulate. This paper proposes an analytical model and an algorithm to analyze as well as determine characteristics of solution spaces of system of ODE. The analytical model employs structural elements of metric spaces. The algorithmic output and analysis illustrate that, the proposed model successfully determines the dynamics of solution intervals as well as structural interactions. © 2017 Susmit Bagchi.

Chung W.S.,Gyeongsang National University | Zare S.,Islamic Azad University at North Tehran | Hassanabadi H.,Shahrood University of Technology
Communications in Theoretical Physics | Year: 2017

In this article, conformable fractional form of Schrödinger equation has been presented. Then in this formalism two different and well-known potential have been come in. Wave function of these potential are obtained in terms of Heun function and energy eigen values of each case is determined as well. © 2017 Chinese Physical Society and IOP Publishing Ltd.

Sargolzaeipor S.,Shahrood University of Technology | Hassanabadi H.,Shahrood University of Technology | Chung W.S.,Gyeongsang National University
Journal of the Korean Physical Society | Year: 2017

In the paper, we consider the two-dimensional oscillator within the framework of the noncommutative q-deformed Dirac oscillator. We discuss the eigenvalues of q-deformed Dirac oscillator in (1+2)-dimensions in the presence of a magnetic field in a Noncommutative phase space formalism. © 2017, The Korean Physical Society.

Chung W.S.,Gyeongsang National University | Kim J.Y.,Gyeongsang National University
Journal of the Korean Physical Society | Year: 2017

In this paper, we consider the quantum mechanics with minimal uncertainty in the momentum, which gives the infrared aspects of quantum mechanics in curved space-time. We use this deformed quantum mechanics to solve some quantum-mechanics examples such as the infinite potential in one dimension, the harmonic oscillator in one dimension and the model of the hydrogen atom in three dimension. © 2017, The Korean Physical Society.

Saderla S.,Gyeongsang National University | Dhayalan R.,Indian Institute of Space Science and Technology | Ghosh A.K.,Indian Institute of Technology Kanpur
Aeronautical Journal | Year: 2017

The paper presents the aerodynamic characterization of a low-speed unmanned aerial vehicle, with cropped delta planform and rectangular cross section, at and around high angles-of-attack using flight test methods. Since the linear models used for identification from flight data at low and moderate angles of attack become unsuitable for accurate parameter estimation at high angles of attack, a non-linear aerodynamic model has to be considered. Therefore, the Kirchhoff's flow separation model was used to incorporate the non-linearity in the aerodynamic model in terms of flow separation point and stall characteristic parameters. The Maximum Likelihood (ML) and Neural Gauss-Newton (NGN) methods were used to perform the parameter estimation on one set of low angle-of-attack and one set of near-stall flight data. It is evident from the estimates that the NGN method, which does not involve solving equations of motion, performs on a par with the classical ML method. This may be attributed to the reason that NGN method uses a neural network which has been trained by performing point to point mapping of the measured flight data. This feature of NGN method enhances its application over a wider envelope of high angles of attack flight data. © 2017 Royal Aeronautical Society.

Kim W.,Korea University | Kim H.-E.,Gyeongsang National University | Lee A.-R.,Gyeongsang National University | Jun A.R.,Korea University | And 3 more authors.
Nucleic Acids Research | Year: 2017

MicroRNAs originate from primary transcripts containing hairpin structures. The levels of mature miR156 influence the leaf number prior to flowering in the life cycle of plants. To understand the molecular mechanism of biogenesis of primary miR156a (pri-miR156a) to mature miR156, a base-pair opening dynamics study was performed using model RNAs mimicking the cleavage site of wild type and B5 bulge-stabilizing mutant pri-miR156a constructs. We also determined the mature miR156 levels and measured leaf numbers at flowering of plants overexpressing the wild type and mutant constructs. Our results suggest that the stabilities and/or opening dynamics of the C15·G98 and U16·A97 base-pairs at the cleavage site are essential for formation of the active conformation and for efficient processing of pri-miR156a, and that mutations of the B5 bulge can modulate mature miR156 levels as well as miR156-driven leaf number phenotypes via changes in the base-pair stability of the cleavage site. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

In refractory cardiogenic shock, veno-arterial extracorporeal membrane oxygenation (ECMO) can be initiated. Although left heart decompression can be accomplished by insertion of a left atrial (LA) or LV cannula using a percutaneous pigtail catheter, the venting flow rate according to catheter size and ECMO flow rate is unknown. We developed an artificial ECMO circuit. 1L saline bag with its pressure set to 20 mmHg was connected to ECMO to mimic LV failure. A pigtail catheter was inserted into the 1 L saline bag to simulate LV unloading. For each pigtail catheter size (5 to 8-Fr) and ECMO flow rate (2.0 to 4.0 L/min), the moving distance of an air bubble which was injected through a three way stopcock was measured in the arterial pressure line between the pigtail catheter and ECMO inflow limb. The flow rate was then calculated. We obtained the following equation to estimate the pigtail catheter flow rate.Pigtail vent catheter flow rate (ml/min) = 8 × ECMO flow rate (L/min) + 9 × Pigtail catheter size (Fr) − 57This equation would aid in designing of a further study to determine optimal venting flow rate. To achieve optimal venting flow, our equation would enable selection of an adequate catheter size. Copyright © 2017 by the American Society for Artificial Internal Organs

Viscarra J.A.,University of California at Berkeley | Wang Y.,University of California at Berkeley | Hong I.-H.,University of California at Berkeley | Hong I.-H.,Gyeongsang National University | Sul H.S.,University of California at Berkeley
Science Signaling | Year: 2017

De novo lipogenesis is precisely regulated by nutritional and hormonal conditions. The genes encoding various enzymes involved in this process, such as fatty acid synthase (FASN), are transcriptionally activated in response to insulin. We showed that USF1, a key transcription factor for FASN activation, directly interacted with the Mediator subunit MED17 at the FASN promoter. This interaction recruited Mediator, which can bring POL II and other general transcription machinery to the complex. Moreover, we showed that MED17 was phosphory-lated at Ser53 by casein kinase 2 (CK2) in the livers of fed mice or insulin-stimulated hepatocytes, but not in the livers of fasted mice or untreated hepatocytes. Furthermore, activation of the FASN promoter in response to insulin required this CK2-mediated phosphorylation event, which occurred only in the absence of p38 MAPK-mediated phosphorylation at Thr570. Overexpression of a nonphosphorylatable S53A MED17 mutant or knockdown of MED17, as well as CK2 knockdown or inhibition, impaired hepatic de novo fatty acid synthesis and decreased triglyceride content in mice. These results demonstrate that CK2-mediated phosphorylation of Ser53 in MED17 is required for the transcriptional activation of lipogenic genes in response to insulin. 2017 © The Authors, some rights reserved.

Kim A.-N.,Gyeongsang National University | Kim H.-J.,Gyeongsang National University | Kerr W.L.,University of Georgia | Choi S.-G.,Gyeongsang National University
Food Chemistry | Year: 2017

The purpose of this study was to evaluate the effect of grinding at different vacuum levels (2.67, 6.67, 13.33, 19.99, and 101.33 kPa) on key quality factors of apple. In the control apple, ground at atmospheric pressure of 101.33 kPa, the antioxidant activities rapidly decreased within the first 30 min, then plateaued thereafter, while enzymatic browning increased. When apples were ground and held under vacuum, changes in color and antioxidant activity were much less, and the least change was measured in samples prepared at the lowest pressure. Model fitting of the data showed that antioxidant activity decreased as a function of the logarithm of the absolute pressure. The results from analysis for key phenolic compounds including chlorogenic acid, procyanidin B2, and epicatechin indicated that these compounds were least changed at vacuum grinding at 2.67 kPa, compared to atmospheric grinding. © 2016 Elsevier Ltd

Pospelova V.,University of Victoria | Kim S.-J.,Gyeongsang National University
Marine Micropaleontology | Year: 2010

Assemblages of organic-walled dinoflagellate cysts collected from 23 surface sediment samples distributed in shallow estuarine waters along the southern South Korean coast show high abundance and diversity. A total of 47 cyst types, representing 27 genera of three orders, were identified and distribution maps of the most common taxa have been produced. The cyst assemblages were dominated by Spiniferites (Gonyaulax cf. spinifera), Brigantedinium spp. (Protoperidinium spp.), and Dubridinium spp. (Diplopsalis spp.). Total cyst concentration varies from 1000 to 8900 cysts per gram of dry sediment, with the highest values observed in the most southern sites of the Marine Fish Ranching Ground (MFRG) of Dongdo Bay, near Saryang Island, and the Outer part of Buk Bay. The Inner Buk Bay and the south-western sites of the MFRG were recognized to be subjected to eutrophication, as indicated by the elevated proportional increase in cysts of heterotrophic species of the genera Dubridinium, Polykrikos and Protoperidinium.Cysts of HAB's causing ichthyotoxic Cochlodinium polykrikoides were not found in Buk Bay, and were otherwise found in most of the studied sites in low proportions, except in Gosung Bay where it comprised up to 41% of the cyst assemblage. This is in agreement with previously observed blooms of C. polykrikoides in Gosung Bay. © 2010 Elsevier B.V.

Park I.-H.,Gyeongsang National University | Medishetty R.,National University of Singapore | Lee S.S.,Gyeongsang National University | Vittal J.J.,Gyeongsang National University | Vittal J.J.,National University of Singapore
Chemical Communications | Year: 2014

Alternate bpeb ligands in the polyrotaxane 2D coordination polymer [Cd(bpeb)(sdb)]·DMA (1) selectively undergo polymerization via a [2+2] cycloaddition reaction to form a polyrotaxane based 3D structure [Cd(bpeb) 0.5(poly-bppcb)0.5(sdb)]·DMA (2) in a single-crystal-to-single-crystal manner. This journal is © the Partner Organisations 2014.

Hwang S.-J.,Mayo Medical School | Hwang S.-J.,Gyeongsang National University | Melenovsky V.,Mayo Medical School | Melenovsky V.,Institute of Clinical and Experimental Medicine IKEM | Borlaug B.A.,Mayo Medical School
Journal of the American College of Cardiology | Year: 2014

Objectives This study investigated the characteristics, evaluation, prognostic impact, and treatment of coronary artery disease (CAD) in patients with heart failure and preserved ejection fraction (HFpEF). Background CAD is common in patients with HFpEF, but it remains unclear how CAD should be categorized, evaluated for, and treated in HFpEF. Methods Clinical, hemodynamic, echocardiographic, treatment, and outcome characteristics were examined in consecutive patients with previous HFpEF hospitalizations who underwent coronary angiography. Results Of the 376 HFpEF patients examined, 255 (68%) had angiographically-proven CAD. Compared with HFpEF patients without CAD, patients with CAD were more likely to be men, to have CAD risk factors, and to be treated with anti-ischemic medications. However, symptoms of angina and heart failure were similar in patients with and without CAD, as were measures of cardiovascular structure, function, and hemodynamics. Compared with patients without CAD, HFpEF patients with CAD displayed greater deterioration in ejection fraction and increased mortality, independent of other predictors (hazard ratio: 1.71, 95% confidence interval: 1.03 to 2.98; p = 0.04). Complete revascularization was associated with less deterioration in ejection fraction and lower mortality compared with patients who were not completely revascularized, independent of other predictors (hazard ratio: 0.56, 95% confidence interval: 0.33 to 0.93; p = 0.03). Conclusions CAD is common in patients with HFpEF and is associated with increased mortality and greater deterioration in ventricular function. Revascularization may be associated with preservation of cardiac function and improved outcomes in patients with CAD. Given the paucity of effective treatments for HFpEF, prospective trials are urgently needed to determine the optimal evaluation and management of CAD in HFpEF. © 2014 by the American College of Cardiology Foundation. Published by Elsevier Inc.

Choi D.S.,Gyeongsang National University | Kim M.C.,Pohang St Marys Hospital | Lee S.K.,Lahey Clinic Medical Center | Willinsky R.A.,Toronto Western Hospital | Terbrugge K.G.,Toronto Western Hospital
Journal of Neurosurgery | Year: 2010

Object. The anatomical evolution and clinical outcome of completely coiled intracranial aneurysms after endovascular embolization have rarely been studied separately. From their prospective database, the authors reviewed follow-up angiography and clinical outcome of 87 patients whose aneurysms were designated as 100% obliterated on immediate postembolization angiography. Methods. Ninety-one aneurysms (56 ruptured and 35 unruptured) in 87 patients were included in this study. Clinical outcome was evaluated using the Glasgow Outcome Scale. Follow-up angiographic findings were assessed and categorized as 1 of the following: no recanalization, recanalization with a neck remnant, or recanalization with a body remnant. For statistical analysis, the recanalization rate was correlated with: clinical presentation; the largest aneurysm diameter, aneurysm neck size, and dome-to-neck ratio; aneurysm location; and use of special techniques such as usage of a surface modified coil, balloon remodeling technique, or stent. Results. At the latest clinical evaluation (mean 34.3 months), 81 (93.1%) of the 87 patients (91 aneurysms) had good clinical outcomes (Glasgow Outcome Scale Score 5). The procedure-related morbidity rate (permanent neurological deficit) was 2.3% (2 of 87), and there were no procedure-related deaths. On the latest follow-up angiography (mean 26.4 months), the recanalization rate was 26.4% (24 of 91 aneurysms): 16 (17.6%) with neck remnants and 8 (8.8%) with body remnants. The neck size of the recanalized aneurysms was statistically significantly larger than that of the nonrecanalized aneurysms (p = 0.006), and aneurysms with wide necks (≥ 4 mm) had a higher recanalization rate than those with a narrow neck (< 4 mm) (p = 0.002). There was no bleeding after endovascular treatment during the follow-up period. Conclusions. Completely coiled aneurysms after endovascular embolization demonstrated good clinical outcome, and there was no bleeding episode after endovascular treatment; however, there was a relatively high recanalization rate.

Jung B.C.,Gyeongsang National University | Shin W.-Y.,Dankook University | Paulraj A.,Stanford University
IEEE Transactions on Signal Processing | Year: 2014

For the multiple-input multiple-output interfering multiple-access channels (IMACs), opportunistic interference alignment (OIA) using the singular value decomposition (SVD)-based beamforming at each user fundamentally reduces the user scaling condition required to achieve any target DoF, compared to that for the single-input multiple-output IMAC. In this paper, we tackle two practical challenges of the existing SVD-based OIA: 1) the need of full feedforward of the selected users' beamforming weight vectors and 2) a low rate achieved based on the exiting zero-forcing receiver. We first propose a codebook-based OIA, in which the weight vectors are chosen from a predefined codebook with a finite size so that information of the weight vectors can be sent to the belonging BS with limited feedforward. We derive the codebook size required to achieve the same user scaling condition as the SVD-based OIA case for both Grassmannian and random codebooks. Surprisingly, it is shown that the derived codebook size is the same for the two codebook methods. Second, we introduce an enhanced receiver at the base stations (BSs) in pursuit of further improving the achievable rate. Assuming no collaboration between the BSs, the interfering links between a BS and the selected users in neighboring cells are difficult to be acquired at the belonging BS. We propose the use of a simple minimum Euclidean distance receiver operating with no information of the interfering links. With the help of the OIA, we show that this new receiver asymptotically achieves the channel capacity as the number of users increases. © 2014 IEEE.

Park K.-M.,Gyeongsang National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2013

In the asymmetric unit of the title polymeric complex, {[Ag(C11H11N3)] (CF3SO3)} n , there are two AgI atoms, two N-(pyridin-3-ylmethyl) pyridine-2-amine ligands (A and B) and two CF3SO3 - anions. One AgI atom is coordinated by two pyridine N atoms from two symmetry-related A ligands in a geometry slightly distorted from linear [N - Ag - N = 173.2 (3)°], forming a left-handed helical chain, while the other AgI atom is coordinated by two pyridine N atoms from two symmetry-related B ligands in a bent arrangement [N - Ag - N = 157.1 (3)°], forming a right-handed helical chain. Both helical chains have the same pitch length [10.4007 (7) Å], propagate along the b-axis direction and are alternately arranged via Ag...Ag [3.0897 (12) Å] and π-π stacking interactions [centroid-centroid distances = 3.564 (7) and 3.518 (6) Å], resulting in the formation of a two-dimensional supramolecular network extending parallel to the ab plane. Intermolecular N - H...O, C - H...O and C - H...F hydrogen-bonding interactions occur between the helical chains and the anions.

Telke A.A.,Gyeongsang National University | Ghodake G.S.,Kyungpook National University | Kalyani D.C.,Konkuk University | Dhanve R.S.,National Taipei University of Technology | Govindwar S.P.,Shivaji University
Bioresource Technology | Year: 2011

Bacillus sp. ADR secretes an extracellular laccase in nutrient broth, and this enzyme was purified up to 56-fold using acetone precipitation and DEAE-cellulose anion exchange chromatography. The molecular weight of purified laccase was estimated to be 66. kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified laccase oxidized 2,6-dimethoxy phenol, o-tolidine, hydroquinone, l-DOPA and guaiacol. The optimum pH for oxidation of o-tolidine, 2,6-dimethoxy phenol and guaiacol were 3.0, 4.0 and 5.0, respectively. The purified laccase contained 2.7. mol/mol of copper. The laccase was stable up to 40 °C and within the pH range of 7.0-9.0. Well-known inhibitors of multicopper oxidases such as, sodium azide, l-cysteine and dithiothreitol showed significant inhibition of laccase activity. The purified enzyme decolorized structurally different azo dyes with variable decolorization rates and efficiencies of 68-90%. This study is useful for understanding the precise use of Bacillus sp. ADR in the decolorization of textile dyes containing industrial wastewater. © 2010 Elsevier Ltd.

Lee H.,Gyeongsang National University | Kim Y.,Korea Institute of Geoscience and Mineral Resources | Jeong Y.,Korea Aerospace Industries Ltd. | Kim S.,Gyeongsang National University
Corrosion Science | Year: 2012

In the present study, the effects of testing variables on stress corrosion cracking (SCC) susceptibility of Al 2024-T351 in 3.5% NaCl solution were examined using slow strain rate test (SSRT) method with controlled applied potentials and a constant load test (CLT) method. The SSRTs were conducted at various strain rates and applied potential, while the CLTs were performed with different exposure time, with different grain directions of ST (short-transverse) and L (longitudinal) to understand how the testing parameters affected on the SCC susceptibility of Al 2024-T351. The percent reductions in tensile elongation in an SCC-causing environment over those in air tended to express the SCC susceptibility of Al 2024-T351 most properly for both SSRT and CLT. The present fractographic examination suggested that both anodic dissolution and hydrogen embrittlement played a role in the SCC process of Al 2024-T351 in 3.5% NaCl solution at both anodic and cathodic applied potentials, and the contribution of each mechanism could vary with different testing variables. It was also found that the SCC susceptibility of Al 2024-T351 obtained from the CLT result could provide the similar SCC evaluation result obtained by SSRT with a proper selection of testing variables. The metallurgical aspect of SCC behaviour of Al 2024-T351 was also discussed based on the microstructural and fractographic examinations. © 2011 Elsevier Ltd.

Biradha K.,Indian Institute of Technology Kharagpur | Su C.-Y.,Sun Yat Sen University | Vittal J.J.,National University of Singapore | Vittal J.J.,Gyeongsang National University
Crystal Growth and Design | Year: 2011

In recent years, Asian countries, especially China and India, are making significant progress in the field of crystal engineering. The recent surge of publications in this area from these countries in high impact journals is a tangible measure of this activity. An important milestone in this direction was the China-India-Singapore Symposium on Crystal Engineering recently held at the National University of Singapore. This symposium brought researchers working in this field to meet, discuss, present, and exchange their research work and has generated momentum to further accelerate the growth of this field. This perspective highlights the recent advances discussed by the researchers at this symposium in the fast growing field of crystal engineering.(Figure Presented) © 2011 American Chemical Society.

Bukhari A.C.,Gyeongsang National University | Tusseyeva I.,Gyeongsang National University | Lee B.-G.,ETRI | Kim Y.-G.,Gyeongsang National University
Expert Systems with Applications | Year: 2013

Due to brisk industrial growth, the marine traffic has become an imperative subject in the open sea nowadays. The crew inside the vehicle traffic service (VTS) centre is facing challenging issues on account of continuous growth in vessel number. Currently, most of VTS centers' are using the ARPA RADAR based conventional vehicle traffic management system and VTS staff has to carry out most of the things manually to guide the ship's captain properly. Therefore, there is a strong impetus in the field of ocean engineering to develop a smart system which can take the data from RADAR and autonomously manipulate it, to calculate the degree of collision risk among all vessels from the VTS centre. Later on, the traffic management officer utilizes this information for intelligent decision making. In the past, several researchers have addressed this issue to facilities the VTS crew and captain of the ship but mostly, their research work was for academic purposes and could not get popularity because of extra manual workload. Our proposed vessel collision risk assessment system is an intelligent solution which is based on fuzzy inference system and has the ability to solve the said issues. We calculated the DCPA, TCPA, bearing and VCD among all vessels ships from the VTS centre by using conventional marine equipments and exploited the extracted information to calculate and display the degree of collision risk among all vessels. Furthermore, we developed the RADAR filtration algorithm which helps the VTS officer to gauge out the degree of collision risk around a particular ship. To authenticate the validity and to monitor the performance efficiency, we developed RADAR operated intelligent software which directly gets the required data from RADAR and displays the vessels list based on their degree of collision severity. The laboratory experiments confirm the validity of the proposed system. © 2012 Elsevier Ltd. All rights reserved.

Nagarathinam M.,National University of Singapore | Saravanan K.,National University of Singapore | Phua E.J.H.,National University of Singapore | Reddy M.V.,National University of Singapore | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2012

MOP(OF) up the lithium: Metal organic-phosphate open framework materials, for example K 2.5[(VO) 2(HPO 4) 1.5(PO 4) 0.5(C 2O 4)] (see scheme), are investigated as hybrid cathode materials for lithium ion batteries. The redox-active metal center, robustness, available two-dimensional migration pathways in the abplane, and cavities along the caxis for the migration of the alkali metal ions allow the rapid insertion and extraction of alkali metal ions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Han X.,Gyeongsang National University | Hyun T.,Gyeongsang National University | Zhang M.,Gyeongsang National University | Zhang M.,CAS Institute of Plant Physiology and Ecology | And 6 more authors.
Developmental Cell | Year: 2014

In plants, auxin functions as a master controller of development, pattern formation, morphogenesis, and tropic responses. A sophisticated transport system has evolved to allow the establishment of precise spatiotemporal auxin gradients that regulate specific developmental programs. A critical unresolved question relates to how these gradients can be maintained in the presence of open plasmodesmata that allow for symplasmic exchange of essential nutrients and signaling macromolecules. Here we addressed this conundrum using genetic, physiological, and cell biological approaches and identified the operation of an auxin-GSL8 feedback circuit thatregulates the level of plasmodesmal-localized callose in order to locally downregulate symplasmic permeability during hypocotyl tropic response. This system likely involves a plasmodesmal switch that would prevent the dissipation of a forming gradient by auxin diffusion through the symplasm. This regulatory system may represent a mechanism by which auxin could also regulate symplasmic delivery of a wide range of signaling agents. © 2014 Elsevier Inc.

Chen H.,Gyeongsang National University | Ahmad M.,Gyeongsang National University | Rim Y.,Gyeongsang National University | Lucas W.J.,University of California at Davis | Kim J.-Y.,Gyeongsang National University
New Phytologist | Year: 2013

Cell-to-cell trafficking of transcription factors (TFs) has been shown to play an important role in the regulation of plant developmental events, but the evolutionary relationship between cell-autonomous and noncell-autonomous (NCA) TFs remains elusive. AtDof4.1, named INTERCELLULAR TRAFFICKING DOF 1 (ITD1), was chosen as a representative NCA member to explore this evolutionary relationship. Using domain structure-function analyses and swapping studies, we examined the cell-to-cell trafficking of plant-specific Dof TF family members across Arabidopsis and other species. We identified a conserved intercellular trafficking motif (ITM) that is necessary and sufficient for selective cell-to-cell trafficking and can impart gain-of-function cell-to-cell movement capacity to an otherwise cell-autonomous TF. The functionality of related motifs from Dof members across the plant kingdom extended, surprisingly, to a unicellular alga that lacked plasmodesmata. By contrast, the algal homeodomain related to the NCA KNOX homeodomain was either inefficient or unable to impart such cell-to-cell movement function. The Dof ITM appears to predate the evolution of selective plasmodesmal trafficking in the plant kingdom, which may well have acted as a molecular template for the evolution of Dof proteins as NCA TFs. However, the ability to efficiently traffic for KNOX homeodomain (HD) proteins may have been acquired during the evolution of early nonvascular plants. See also the Commentary by Horton et al. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Leong W.L.,National University of Singapore | Vittal J.J.,Gyeongsang National University
Chemical Reviews | Year: 2011

Complexity and diversity in structures, properties, and applications are examined. Zigzag type conformation is also ubiquitous in 1D CPs. The construction of zigzag CPs stemmed from flexible exoditopic ligands and linear or cis-coordinated octahedral metal centers or tetrahedral metal ions. Infinite helical structural motif has special place in supramolecular chemistry because of its similarities in biological systems and enantioselective catalysis. Generally, utilization of flexible or chiral ligands is a facile approach to achieve helical CPs, while many successful examples of spontaneous chirality induction from achiral ligands also have been widespread in the literature. Conformationally flexible ligands are the key success of self-assembly of structural motifs, such as polycatenanes, helices, braids, Borromean rings and rotaxanes.

Kole G.K.,National University of Singapore | Vittal J.J.,National University of Singapore | Vittal J.J.,Gyeongsang National University
Chemical Society Reviews | Year: 2013

This tutorial review discusses recent literature on coordination polymers and metal-organic frameworks (MOFs) that exhibit solid-state reactivity and structural transformation under various experimental conditions. Removal or exchange of solvents and guest molecules, exposure to reactive vapours, and external stimuli such as heat, light or mechanochemical force cause such structural transformations and these are often manifested by various physical properties such as colour, magnetism, luminescence, chirality, porosity, etc. due to change in coordination number and geometry, dimensionality, interpenetration, etc. More drastic transformations related to the exchange of metal ions, pillar ligands and insertion of additional ligands between the layers have also been demonstrated. The vast area of dynamic behaviour of coordination polymers and their stimuli-responsive properties have also been addressed briefly. © 2013 The Royal Society of Chemistry.

Ma S.,University of California at Davis | Shah S.,University of California at Davis | Bohnert H.J.,University of Illinois at Urbana - Champaign | Bohnert H.J.,Gyeongsang National University | And 2 more authors.
PLoS Genetics | Year: 2013

Understanding of gene regulatory networks requires discovery of expression modules within gene co-expression networks and identification of promoter motifs and corresponding transcription factors that regulate their expression. A commonly used method for this purpose is a top-down approach based on clustering the network into a range of densely connected segments, treating these segments as expression modules, and extracting promoter motifs from these modules. Here, we describe a novel bottom-up approach to identify gene expression modules driven by known cis-regulatory motifs in the gene promoters. For a specific motif, genes in the co-expression network are ranked according to their probability of belonging to an expression module regulated by that motif. The ranking is conducted via motif enrichment or motif position bias analysis. Our results indicate that motif position bias analysis is an effective tool for genome-wide motif analysis. Sub-networks containing the top ranked genes are extracted and analyzed for inherent gene expression modules. This approach identified novel expression modules for the G-box, W-box, site II, and MYB motifs from an Arabidopsis thaliana gene co-expression network based on the graphical Gaussian model. The novel expression modules include those involved in house-keeping functions, primary and secondary metabolism, and abiotic and biotic stress responses. In addition to confirmation of previously described modules, we identified modules that include new signaling pathways. To associate transcription factors that regulate genes in these co-expression modules, we developed a novel reporter system. Using this approach, we evaluated MYB transcription factor-promoter interactions within MYB motif modules. © 2013 Ma et al.

Levine G.N.,Baylor College of Medicine | Jeong Y.-H.,Gyeongsang National University | Goto S.,Tokai University | Anderson J.L.,University of Utah | And 4 more authors.
Nature Reviews Cardiology | Year: 2014

Guideline recommendations on the use of dual antiplatelet therapy (DAPT) in patients with acute coronary syndromes and in those undergoing percutaneous coronary intervention (PCI) have been formulated by both the ACC/AHA and the ESC. These recommendations are based primarily on large, phase III, randomized, controlled trials of the P2Y 12 inhibitors clopidogrel, prasugrel, and ticagrelor. However, few East Asian patients have been included in the trials to assess the use of these agents, particularly the newer agents prasugrel and ticagrelor. Additionally, an increasing body of data suggests that East Asian patients have differing risk profiles for both thrombophilia and bleeding compared with white patients, and that a different 'therapeutic window' of on-treatment platelet reactivity might be appropriate in East Asian patients. Furthermore, a phenomenon referred to as the 'East Asian paradox' has been described, in which East Asian patients have a similar or even a lower rate of ischaemic events after PCI compared with white patients, despite a higher level of platelet reactivity during DAPT. Recognizing these concerns, the World Heart Federation has undertaken this evidence-based review and produced this expert consensus statement to determine the antiplatelet treatment strategies that are most appropriate for East Asian patients. © 2015 Macmillan Publishers Limited.

Suantai S.,Chiang Mai University | Cho Y.J.,Gyeongsang National University | Cholamjiak P.,University of Phayao
Computers and Mathematics with Applications | Year: 2012

We investigate strong convergence for Bregman strongly nonexpansive mappings by Halpern's iteration in the framework of reflexive Banach spaces. Using the obtained result, convergence for a family of Bregman strongly nonexpansive mappings is also discussed. As applications, we apply our main result to problems of finding zeros of maximal monotone operators and equilibrium problems in reflexive Banach spaces. © 2011 Elsevier Ltd. All rights reserved.

Lee S.Y.,Gyeongsang National University | Jung J.H.,Gyeongsang National University | Vittal J.J.,Gyeongsang National University | Vittal J.J.,National University of Singapore | Lee S.S.,Gyeongsang National University
Crystal Growth and Design | Year: 2010

The solvent-dependent double-stranded one-dimensional (1-D) coordination polymer [Ag2L2(C104)2]n (1) and another 1-D polymer {[Ag2L2(CH3CN)] -2ClO4}Jn (2a) with the shape of a cut of tube along the long axis were obtained in the reactions of a 16membered O2S 2-macrocycle L with silver(I) Perchlorate in DCM/MeOH and CH 3CN, respectively. Time-dependent crystallization experiments unambiguously show that 2a is a kinetic product and transforms into a thermodynamically more stable [AgLC104]n(2b) with a two-dimensional square-grid structure. © 2010 American Chemical Soc.

Rana A.S.,Gyeongsang National University | Struchtrup H.,University of Victoria
Physics of Fluids | Year: 2016

A phenomenological approach to the boundary conditions for linearized R13 equations is derived using the second law of thermodynamics. The phenomenological coefficients appearing in the boundary conditions are calculated by comparing the slip, jump, and thermal creep coefficients with linearized Boltzmann solutions for Maxwell's accommodation model for different values of the accommodation coefficient. For this, the linearized R13 equations are solved for viscous slip, thermal creep, and temperature jump problems and the results are compared to the solutions of the linearized Boltzmann equation. The influence of different collision models (hard-sphere, Bhatnagar-Gross-Krook, and Maxwell molecules) and accommodation coefficients on the phenomenological coefficients is studied. © 2016 AIP Publishing LLC.

Hwang S.,Gyeongsang National University | Batmunkh M.,University of Adelaide | Nine M.J.,University of Adelaide | Chung H.,Gyeongsang National University | Jeong H.,Gyeongsang National University
ChemPhysChem | Year: 2015

Dye-sensitized solar cells (DSSCs) have received significant attention from the scientific community since their discovery in 1991. However, the high cost and scarcity of platinum has motivated researchers to seek other suitable materials for the counter electrode of DSSCs. Owing to their exceptional properties such as high conductivity, good electrochemical activity, and low cost, carbon nanotubes (CNTs) have been considered as promising alternatives to expensive platinum (Pt) in the counter electrode of DSSCs. Herein, we provide a Minireview of the CNTs use in the counter electrode of DSSCs. A brief overview of Pt-based counter electrodes is also discussed. Particular attention is given to the recent advances of counter electrodes with CNT-based composite structures. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA , Weinheim.

Park I.-H.,Gyeongsang National University | Kim K.,Gyeongsang National University | Lee S.S.,Gyeongsang National University | Vittal J.J.,Gyeongsang National University | Vittal J.J.,National University of Singapore
Crystal Growth and Design | Year: 2012

This communication describes a unique interweaving of a pyridyl-based long linear spacer ligand, 1,4-bis[2-(4-pyridyl)ethenyl]benzene (bpeb), in the triply interpenetrated pillar-layer porous coordination polymer [Zn 2(ndc) 2(bpeb)]•DMF•3H 2O(where ndc = 2,6-naphthalenedicarboxylate) containing a paddle-wheel secondary building unit (SBU) with α-Po topology. When the dicarboxylate is changed diethylpyrocarbonate (DEPC) fromndc to biphenyl-4,4′-dicarboxylate (bpdc), the reaction furnished a completely different 3-fold interpenetrating three-dimensional coordination polymer [Zn 3(bpdc) 3(bpeb)] •0.5DMSO•1.5H 2O having a uninodal eight connected network structure with hexagonal bipyramidal SBUs. © 2012 American Chemical Society.

Kole G.K.,National University of Singapore | Tan G.K.,National University of Singapore | Vittal J.J.,National University of Singapore | Vittal J.J.,Gyeongsang National University
Crystal Growth and Design | Year: 2012

An attempt has been made to orient the C=C bonds in trans-3-(3′- pyridyl)acrylic acid (3-PAH) and trans-3-(4′-pyridyl)acrylic acid (4-PAH) in the hydrogen-bonded coordination complexes and coordination polymers of Ag(I), utilizing the argentophilic interaction. Both neutral and deprotonated ligands were employed to synthesize the following compounds: [Ag(3-PAH) 2](BF 4) (1), [Ag(3-PAH) 2](ClO 4) (2), [Ag(4-PAH) 2](ClO 4)•H 2O (3), [Ag(3-PA)]•1.5H 2O (4), and [Ag(4-PA)] (5). Of these, 1-2 are isotypical hydrogen-bonded polymers of Ag(I) complexes and 3 is a hydrogen-bonded dimer, whereas 4 and 5 are coordination polymers. Compounds 1-4 undergo photodimerization in head-to-head fashion in the solid state. The photoreactivity of these compounds in solution was also investigated. The head-to-head photodimerized product of 4-PAH, namely, 3,4-bis(4′-pyridyl) cyclobutane-1,2-dicarboxylic acid (HH-4,4-BPCD), has been shown to be a potential ligand for synthesizing coordination polymers, by the isolation of [Ag 2(HH-4,4-BPCD)(H 2O)]•(2H 2O)( 1/ 2MeOH), which has a two-dimensional polymeric structure in the solid state. © 2011 American Chemical Society.

Shahul Hameed A.,National University of Singapore | Nagarathinam M.,National University of Singapore | Reddy M.V.,National University of Singapore | Chowdari B.V.R.,National University of Singapore | And 2 more authors.
Journal of Materials Chemistry | Year: 2012

The layer structured α I-LiVOPO 4 was obtained via a two step chemical synthesis. In the first step, a hydrated phase, LiVOPO 4·2H 2O, was obtained by a simple hydrothermal route at 120 °C. Single crystal X-ray diffraction analysis revealed the structure of LiVOPO 4·2H 2O to be orthorhombic with lattice parameters: a = 8.9454(7) Å, b = 9.0406(7) Å and c = 12.7373(10) Å. Dehydration of the parent compound led to its structural transformation to tetragonal α I-LiVOPO 4, which was only identified previously during the lithium insertion in VOPO 4. We have investigated the solid-state dehydration of LiVOPO 4· 2H 2O and proposed a possible mechanism for the crystal structure transformation. Electrochemical characterization of this rarely studied tetragonal phase revealed its good lithium cycling at high operating voltage. Galvanostatic charge-discharge cycling of α I-LiVOPO 4 was studied in a voltage window of 2.5-4.5 V, which shows a stable reversible capacity of 103(±3) mA h g -1 at a current density of 16 mA g -1 (0.1 C). At higher current rates, although it exhibited good cyclability, the capacity was found to decrease with increasing current rates. The long term cycling stability of the above material was demonstrated at a current rate of 0.5 C up to 200 cycles. © 2012 The Royal Society of Chemistry.

Park K.-M.,Gyeongsang National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2012

The title cocrystal, C10H8N2·C 6H6O4, crystallizes with half-mol-ecules of 4,4′-bipyridine and trans,trans-hexa-2,4-dienedioic acid in the asymmetric unit, as each is located about a crystallographic inversion center. The bipyridine molecule is planar from symmetry. In the dicarboxylic acid molecule, the O-C-C-C torsion angle is-13.0 (2)°. In the crystal, O-H⋯N and C-H⋯O hydrogen bonds generate a three-dimensional network.

Medishetty R.,National University of Singapore | Jung D.,Gyeongsang National University | Song X.,Ulsan National Institute of Science and Technology | Kim D.,Ulsan National Institute of Science and Technology | And 4 more authors.
Inorganic Chemistry | Year: 2013

Three novel soft porous coordination polymer (PCP) or metal-organic framework (MOF) compounds have been synthesized with a new rigid ligand N-(4-pyridyl)-1,4,5,8-naphathalenetetracarboxymonoimide (PNMI) by partial hydrolysis of N,N′-di-(4-pyridyl)-1,4,5,8-naphthalenete-tracarboxydiimide (DPNI) during solvothermal reactions with Zn(II), Cd(II), and Mn(II) salts, and they are [Zn(PNMI)]·2DMA (1·2DMA, 1a), [Cd(PNMI)]·0. 5DMA·5H2O (2·0.5DMA·5H2O), and [Mn(PNMI)]·0.75DMF (3·0.75DMF). The structure of 1 is based on paddle-wheel secondary building unit (SBU) with a 3,6-connected rtl net topology, whereas 2 and 3 are isotypical but the M(O2C-C)2 fragments aggregate in one-dimension and the overall connectivity is the same rtl net topology. All these three MOFs have one-dimensional rhombic channels filled with guest molecules. The guest molecules in 1a can be exchanged with EtOH in a single-crystal to single-crystal (SCSC) manner to 1·1. 25EtOH·0.375H2O (1b). Further, the guest molecules in 1b can be replaced with ethylene glycol, triethylene glycol and allyl alcohol without destroying its single crystal nature. These guest exchanges are accompanied by reduction in volume of the unit cell up to 16%, as well as the void volume up to 33.1%. Similarly, triethylene glycol (TEGly) selectively exchanges EtOH in a mixture of the above solvents, which might be the result of correct fit of the hydrogen-bonded TEGly dimer in the channel of 1. While activated 1 and 3 exhibit no uptake of N2 and H2 at 1 bar and 77 K and very low uptake of CO2 gas at 1 bar and 196 K, activated 2 shows selective CO2 uptake, 278 cm2·g-1, over N 2 and H2 at 1 bar and 196 K, which corresponds to 5.87 molecules of CO2 per formula unit of 2. © 2013 American Chemical Society.

Medishetty R.,National University of Singapore | Koh L.L.,National University of Singapore | Kole G.K.,National University of Singapore | Vittal J.J.,National University of Singapore | Vittal J.J.,Gyeongsang National University
Angewandte Chemie - International Edition | Year: 2011

Construction by shining light! A [2+2] cycloaddition reaction in a 2D coordination polymer accompanied by single-crystal-to-single-crystal structural transformation to a 3D structure highlights the retrosynthesis of a 3D structure from a 2D layer compound (see scheme, Zn red, 4-styrylpyridine blue/turquoise). © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nagarathinam M.,National University of Singapore | Chanthapally A.,National University of Singapore | Lapidus S.H.,State University of New York at Stony Brook | Stephens P.W.,State University of New York at Stony Brook | And 2 more authors.
Chemical Communications | Year: 2012

Grinding of a one-dimensional (1-D) ladder coordination polymer (CP), [Zn(μ-CH 3CO 2)(CF 3CO 2)bpe] (1), and a hydrogen-bonded 1-D CP, [Cd(CH 3CO 2) 2bpe(H 2O)] (2), with KBr resulted in the exchange of carboxylate by bromide ions and the formation of 1-D zigzag and 2-D CPs respectively. This journal is © The Royal Society of Chemistry 2012.

Park I.-H.,Gyeongsang National University | Chanthapally A.,National University of Singapore | Lee H.-H.,Gyeongsang National University | Quah H.S.,National University of Singapore | And 3 more authors.
Chemical Communications | Year: 2014

The bpeb ligands aligned in a slip-stacked manner in a two-fold interpenetrated non-porous metal-organic framework (MOF) [Zn2(bpeb) (bdc)(fa)2] undergo [2+2] cycloaddition reaction in a single-crystal to single-crystal manner to a non-interpenetrated 3D structure with a new topology comprising an organic polymer ligand and a 2D coordination polymer. This journal is © the Partner Organisations 2014.

Park I.-H.,Gyeongsang National University | Medishetty R.,National University of Singapore | Kim J.-Y.,Gyeongsang National University | Lee S.S.,Gyeongsang National University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014

Distortional isomers, or bond-stretch isomers, differ only in the length of one or more bonds, which is due to crystallographic disorder in most cases. The term distortional isomerism is introduced to describe the structures of polyrotaxane 2D coordination polymers (CPs) that differ only by the relative positions in the neighboring entangled axles. A large ring and a long spacer ligand in 2D CPs yielded four different supramolecular isomers, of which two have an entangled polyrotaxane structure. One pair of C≡C bonds in the spacer ligand is well-aligned in one isomer and undergoes [2+2] cycloaddition reaction, whereas the other isomer is photoinert. They also have different sensing efficiency for several aromatic nitro compounds. However, both isomers show selective PL quenching for the Brady's reagent. Structurally similar supramolecular isomers with different photochemical reactivity and sensing abilities appear to be unprecedented. Polyrotaxane isomers! Of the four supramolecular isomers of coordination polymers synthesized, two have polyrotaxane structures that differ only in the relative positions of the wheel in the neighboring axle. They show different photoreactivity under UV light as well as sensing abilities of a number of organic nitro compounds. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim D.H.,Kunsan National University | Kim Y.J.,Kunsan National University | Hur D.S.,Gyeongsang National University
Ocean Engineering | Year: 2014

A new approach to damage estimation of breakwater armor blocks was developed by incorporating a wave height prediction artificial neural network (ANN) into a Monte Carlo simulation (MCS). The ANN was used to predict the wave height in front of a breakwater, with both the deep water wave heights and tidal level being input to the ANN. The waves predicted by the ANN were comparable to those from a wave transform analysis. Using an ANN in wave prediction makes it possible to very simply and quickly obtain numerous waves near the breakwater. Eventually, the analysis time for the expected damage can be reduced. In addition, the effect of the tidal level on the expected damage was revealed by numerical examples. In these numerical examples, it was found that the tidal variation should be taken into account when estimating the expected breakwater damage. © 2014 Elsevier Ltd.

Chen S.,Shanghai University | Chen S.,University of Technology, Sydney | Wang Y.,Shanghai University | Ahn H.,Gyeongsang National University | Wang G.,University of Technology, Sydney
Journal of Power Sources | Year: 2012

Tin-graphene nanocomposites are prepared by a combination of microwave hydrothermal synthesis and a one-step hydrogen gas reduction. Altering the weight ratio between tin and graphene nanosheets has critical influences on their morphologies and electrochemical performances. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) analysis confirm the homogeneous distribution of tin nanoparticles on the surface of graphene nanosheets. When applied as an anode material in lithium ion batteries, tin-graphene nanocomposite exhibits a high lithium storage capacity of 1407 mAh g -1. The as-prepared tin-graphene nanocomposite also demonstrates an excellent high rate capacity and a stable cycle performance. The superior electrochemical performance could be attributed to the synergistic effect of the three-dimensional nanoarchitecture, in which tin nanoparticles are sandwiched between highly conductive and flexible graphene nanosheets. © 2012 Elsevier B.V.

Park I.-H.,Gyeongsang National University | Lee S.S.,Gyeongsang National University | Vittal J.J.,Gyeongsang National University | Vittal J.J.,National University of Singapore
Chemistry - A European Journal | Year: 2013

Solvothermal reaction of Zn(NO3)2×4 H 2O, 1,4-bis[2-(4-pyridyl)ethenyl]benzene (bpeb) and 4,4′-oxybisbenzoic acid (H2obc) in the presence of dimethylacetamide (DMA) as one of the solvents yielded a threefold interpenetrated pillared-layer porous coordination polymer with pcu topology, [Zn2(bpeb)(obc)2]×5 H2O (1), which comprised an unusual isomer of the well-known paddle-wheel building block and the trans-trans-trans isomer of the bpeb pillar ligand. When dimethylformamide (DMF) was used instead of DMA, a supramolecular isomer [Zn2(bpeb) (obc)2]×2 DMF×H2O (2), with the trans-cis-trans isomer of the bpeb ligand with a slightly different variation of the paddle-wheel repeating unit, was isolated. In MeOH, single crystals of 2 were transformed by solvent exchange in a single-crystal-to-single-crystal (SCSC) manner to yield [Zn2(bpeb)(obc)2]×2 H 2O (3), which is a polymorph of 1. SCSC conversion of 3 to 2 was achieved by soaking 3 in DMF. Compounds 1 and 2 as well as 2 and 3 are supramolecular isomers. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bae I.-G.,Gyeongsang National University
Journal of Clinical Microbiology | Year: 2013

The performance of the BacT/Alert FA Plus and FN Plus resin bottles was evaluated in comparison with that of standard aerobic (SA) and standard anaerobic (SN) bottles. Twenty milliliters of blood from adult patients was equally distributed into four types of bottles: FA Plus, FN Plus, SA, and SN. The detection of clinically significant organisms and the time to detection (TTD) were monitored for each bottle. Among the 3,103 blood culture sets that were requested, the blood volume of each bottle was over 4 ml in 1,481 sets (47.7%). Among these 1,481 sets, 158 cultures grew in the FA Plus and SA bottles, and 136 grew in the FN Plus and SN bottles. Growth in only one type of bottle was more commonly observed for the FA Plus (n = 38) than for the SA (n = 14) (P = 0.001) bottles and for the FN Plus (n = 27) than for the SN (n = 10) (P = 0.008) bottles. Gram-negative bacilli were more frequently isolated in the resin bottles (P < 0.05). The skin contamination rate was 1.2% in the resin bottles and the standard bottles. The mean TTD was 11.1 h in the FA Plus bottles versus 13.1 h in the SA bottles (P < 0.001) and 12.0 h in the FN Plus bottles versus 12.8 h in the SN bottles (P = 0.083). Clinically significant bacteria, including Gram-negative bacilli, were isolated more frequently from the resin bottles than from the standard bottles. Clinically significant bacteria were detected faster using the aerobic resin bottles than using the standard aerobic bottles. This finding might not be applicable to the standard-practice 10-ml protocol for each bottle because the results from using a smaller volume (5 ml) might be less pronounced. Copyright © 2013, American Society for Microbiology. All Rights Reserved.

Park I.-H.,Gyeongsang National University | Chanthapally A.,National University of Singapore | Zhang Z.,University of South Florida | Lee S.S.,Gyeongsang National University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014

Organic polymers are usually amorphous or possess very low crystallinity. The metal complexes of organic polymeric ligands are also difficult to crystallize by traditional methods because of their poor solubilities and their 3D structures can not be determined by single-crystal X-ray crystallography owing to a lack of single crystals. Herein, we report the crystal structure of a 1D ZnII coordination polymer fused with an organic polymer ligand made insitu by a [2+2] cycloaddition reaction of a six-fold interpenetrated metal-organic framework. It is also shown that this organic polymer ligand can be depolymerized in a single-crystal-to-single-crystal (SCSC) fashion by heating. This strategy could potentially be extended to make a range of monocrystalline metal organopolymeric complexes and metal-organic organopolymeric hybrid materials. Such monocrystalline metal complexes of organic polymers have hitherto been inaccessible for materials researchers. Make or break: A 3D structure consisting of an organic polymer containing cyclobutane rings blended with a ZnII coordination polymer was obtained through a photochemical polymerization reaction. Monocrystalline metal complexes of organic polymer ligands are hitherto unknown. The organic polymer can be depolymerized by cleavage of the cyclobutane rings in a single-crystal-to-single-crystal manner. © 2014 WILEY-VCH Verlag GmbH.

Roh H.S.,Gyeongsang National University | Park K.C.,New Zealand Institute for Plant and Food Research | Park C.G.,Gyeongsang National University
Journal of Economic Entomology | Year: 2012

Thirty-four essential oils were screened for their repellent activities against the twospotted spider mite, Tetranychus urticae Koch (Acarina: Tetranychidae), at 0.1% concentration level using choice and no-choice laboratory bioassays. Of these, 20 essential oils showed significant repellencies against T. urticae in the choice tests. In subsequent no-choice tests using these 20 essential oils, only sandalwood oil showed significant repellency against T. urticae. Total number of eggs oviposited by T. urticae was significantly lower than controls in the choice tests when the kidney bean leaves were treated with 1 of 14 essential oils. The significant repellency of sandalwood oil against T. urticae lasted at least for 5 h at the 0.1% concentration level. Our GC-MS analysis indicated that the major components of the sandalwood oil were α-santalol (45.8%), β-santalol (20.6%), β-sinensal (9.4%), and epi-β-santalol (3.3%). Santanol, a mixture of the two main components in the sandalwood oil, appears to be responsible for the repellency of sandalwood oil against T. urticae. © 2012 Entomological Society of America.

Chanthapally A.,National University of Singapore | Kole G.K.,National University of Singapore | Qian K.,Beihang University | Tan G.K.,National University of Singapore | And 3 more authors.
Chemistry - A European Journal | Year: 2012

Three coordination polymers, [Cd 2achtungtrenung(pvba) 2achtungtrenung(tbdc)achtungtrenung(dmf) 2] (1), [co 2-achtungtrenung(pvba) 2achtungtrenung(tbdc) achtungtrenung(dmf) 2achtungtrenung(h 2o) 2] (2), and [ni 2achtungtrenung(pvba)2achtungtrenung(tbdc)achtungtrenung(dmf) 2achtungtrenung(H 2O) 2] (3) (H 2tbdc=2,3,5,6-tetrabromobenzenedicarboxylic acid, Hpvba=trans-2-(4'-pyridyl)vinylbenzoic acid), were synthesized by solvothermal methods. The solid-state structures of compounds 1 and 2 were determined by X-ray crystallography. In compounds 1 and 2, the bimetallic cores acted as secondary building units that connected the tbdc ligands in one direction and a pair of pvba ligands, which were aligned in a head-to-tail parallel manner, in the orthogonal direction to form sheet structures. The C=C bonds in these pvba ligand pairs in all three compounds were well-aligned to undergo quantitative [2+2] cycloaddition reactions in the solid state under UV irradiation, thereby yielding their cyclobutane derivatives. This photochemical reaction appeared to facilitate structural transformations from one 2D structure into another in the solid state. The photoreactive CoII-and N iII coordination polymers exhibited a reversible dehydration-rehydration reaction that was accompanied by color changes from pink to purple and green to yellow, respectively, owing to a change in coordination number from six to five. Magnetic studies showed that compound 2 was an antiferromagnet, which displayed a field-dependent transition with a critical field (H c) of 40 kOe at 2 K; the antiferromagnetic interaction between the Co 2 units was strengthened and weakened by dehydration and UV irradiation, respectively. The cyclobutane ligand in the photodimerized products was cleaved on heating to yield a mixture of trans-and cis-isomers of pvba, as monitored by 1H NMR spectroscopy. The Cd II coordination polymer underwent quantitative cleavage of the cyclobutane ring whilst the other two underwent partial cleavage. © 2012 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.

Peng Y.F.,National Chi Nan University | Sau A.,Gyeongsang National University
Physics of Fluids | Year: 2015

Hysteretic in-phase ↔ anti-phase exchange of vortex shedding and co-existence of reverse-synchronized bistable wake structures past two side-by-side elliptic/circular cylinders are examined through extensive numerical simulations and bifurcation analysis. Wake characteristics and synchronizations past two side-by-side cylinders have often been demarcated in terms of the gap-ratio "G" and the Reynolds number "Re." The focus here is the "in-phase↔anti-phase" two-way transition of oppositely synchronized bistable shedding states. In a remarkable parallel to discontinuous shifts of Strouhal frequency (prompting growth of two distinct instability modes past a single cylinder), the present work reveals interesting in-phase↔anti-phase transitional switching of vortex shedding past two side-by-side symmetric cylinders, as facilitated by "discontinuous jumps of combined lift-force CL,1+2," and preceding bistable wake evolution via both of these two reverse-synchronized phases. The hysteresis loops are demarcated (for cylinders of different aspect-ratios A) through extended computations of two anti-synchronized solution branches by slowly increasing/decreasing the Re at fixed gap-ratio (G) and increasing/decreasing G minutely at a constant Re, thereby facilitating transitions and using the computed discontinuous jumps of CL,1+2. Simulations conducted with various A (0.5 ≤ A ≤ 2.0) exhibit, both in-phase and anti-phase shedding co-exist over significantly wide ranges of G-space/Re-space, and the exchange of vortex synchronization at the ends of hysteresis loop occurs through discontinuous variation of the CL,1+2. The "gap-biased" anti-phase → inphase transition gets gradually delayed, as the cylinder aspect-ratio A is decreased. However, the "Re-biased" in-phase → anti-phase transition is advanced with the decrease of A. The tolerance width "HW" of gap-biased hysteresis loop increases fairly linearly, as A decreased over the range 1.0 ≤ A ≤ 2.0. © 2015 AIP Publishing LLC.

Jeong D.-H.,Gyeongsang National University | Lee S.-G.,POSCO | Jang W.-K.,POSCO | Choi J.-K.,POSCO | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

In the current study, the S-N fatigue and the fatigue crack propagation (FCP) behaviors of high manganese austenitic steels, including Fe24Mn and Fe22Mn, were studied, and the results were compared with STS304 (Fe-1Si-2Mn-20Cr-10Ni). The S-N fatigue tests were conducted at 298 K and 110 K (25 C and -163 C), respectively, and at an R ratio of 0.1 under a uniaxial loading condition. The FCP tests were conducted at 298 K and 110 K (25 C and -163 C), respectively, and at R ratios of 0.1 and 0.5, respectively, using compact tension specimens. The resistance to S-N fatigue of each specimen increased greatly with decreasing temperature from 298 K to 110 K (25 C to -163 C) and showed a strong dependency on the flow stress. The FCP behaviors of the austenitic steels currently studied substantially varied depending on testing temperature, applied ΔK (stress intensity factor range), and R ratio. The enhanced FCP resistance was observed for the Fe24Mn and the Fe22Mn specimens particularly in the near-threshold ΔK regime, while the enhancement was significant over the entire ΔK regimes for the STS304 specimen, with decreasing temperature from 298 K to 110 K (25 C to -163 C). The S-N fatigue and the FCP behaviors of high manganese austenitic steels are compared with STS304 and discussed based on the fractographic and the micrographic observations. © 2013 The Minerals, Metals & Materials Society and ASM International.

Qin X.,Hangzhou Normal University | Chang S.-S.,Yibin University | Cho Y.J.,Gyeongsang National University
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, we consider an iterative method for finding a common element of the set of a generalized equilibrium problem, of the set of solutions to a system of variational inequalities and of the set of fixed points of a strict pseudo-contraction. Strong convergence theorems are established in the framework of Hilbert spaces. The results presented in this paper improve and extend the corresponding results announced by many others. © 2009 Elsevier Ltd. All rights reserved.

Chauhan K.,Himachal Pradesh University | Chauhan G.S.,Himachal Pradesh University | Ahn J.-H.,Gyeongsang National University
Industrial and Engineering Chemistry Research | Year: 2010

In this article we report use of novel starch-based functional hydrogels as Cu2+ ions sorbents. Starch was functionalized by acid hydrolysis and/or oxidized by nitrogen oxides to generate carboxylic groups at C-6. Sorption of Cu2+ ions was studied as a function of hydrogel structure and environmental factors. Hydrogels exhibit structure-property relationship in the sorption of Cu2+ ions. The hydrogel that exhibited the maximum ion uptake was used to investigate the effect of contact time, temperature, pH, and Cu2+ ions concentration on the sorption capacity. The maximum sorption capacity of 128.26 mg g-1 was obtained in 2 h at 40 °C, 7.0 pH, and 50 ppm of Cu2+ ions. Sorption data show good match both with Langmuir and Freundlich isotherms and obey pseudo-second-order kinetics. Cu 2+ ions bind to sorbents by chelation. Evidence of Cu2+ uptake on hydrogels was obtained from FTIR spectrum of the ions-loaded hydrogel. © 2010 American Chemical Society.

Kole G.K.,National University of Singapore | Koh L.L.,National University of Singapore | Lee S.Y.,Gyeongsang National University | Lee S.S.,Gyeongsang National University | And 2 more authors.
Chemical Communications | Year: 2010

A novel method to access rctt-1,2,3,4-tetrakis-(4′-carboxyphenyl)- cyclobutane in quantitative yield from an environmentally benign route is presented. The cyclobutane derivative is demonstrated as a potential candidate to serve as an organic building block for making co-crystal and MOF. © 2010 The Royal Society of Chemistry.

Park K.-M.,Gyeongsang National University
Acta Crystallographica Section E: Structure Reports Online | Year: 2014

In the title polymeric complex, {[Ag(C11H11N 3)]PF6}n, the AgI ion is two-coordinated in a nearly linear coordination geometry [N-Ag-N = 175.98 (9)°] by two pyridine N atoms from two symmetry-related N-[(pyridine-2-yl)methyl]-pyridine-3-amine ligands. Each AgI ion is bridged by the ligands, forming a helical chain propagating along the b-axis direction. The right- and left-handed helical chains are alternately arranged via Ag⋯Ag [3.2639 (5) Å] and π-π stacking interactions [centroid-centroid distance = 3.523 (1) Å], resulting in the formation of a two-dimensional supramolecular network extending parallel to (101). Weak Ag⋯F interactions [longest Ag⋯F interaction = 3.153 (2) Å], as well as N-H⋯F and C-H⋯F hydrogen-bonding interactions, occur between the helical chains and the anions.

Holtzhausen D.,Stellenbosch University | Kim Y.,Gyeongsang National University
Applied Mechanics and Materials | Year: 2013

This paper is concerned with optimisation of the power produced by a photovoltaic (PV) panel through designing, building and implementing maximum power point tracking (MPPT). In the literature, the MPPT has been normally approached either electronically (using a DC-to-DC converter) or mechanically (controlling the orientation of a PV panel). In this paper, these two approaches are combined to yield more power. To this end, for a given PV panel (available at the first author's institution) which is already equipped with a mechanical tracking device, a Buck (DC-to-DC) converter is designed to improve the power saving which could be achieved by the mechanical tracking alone. Also, new electronic and mechanical MPPT methods are developed, and their combination, so-called electro-mechanical MPPT, is tested in a real environment to verify its usefulness. © (2013) Trans Tech Publications, Switzerland.

Khang D.,Gyeongsang National University | Choi J.,Gyeongsang National University | Im Y.-M.,Gyeongsang National University | Kim Y.-J.,Kyungpook National University | And 5 more authors.
Biomaterials | Year: 2012

Subnano, nano and sub-micron surface features can selectively activate integrin receptors and induce osteoblast differentiation of bone marrow mesenchymal stem cells. Although it is widely accepted that nanoscale titanium surface roughness may promote differentiation of various osteoblast lineages, there has been no clear report on the threshold dimension of surface features and the optimized dimensions of surface features for triggering integrin activation and stem cell differentiation. This study systematically controlled titanium surface features from the sub-nano to sub-micron scales and investigated the corresponding effects on stem cell responses, such as integrin activation, cyclins, key transcriptional genes of osteoblast differentiation and osteoblastic phenotype genes. Surface features with sub-nano surface dimensions were insufficient to increase integrin activation compared to pure nanoscale titanium surface features. Although both pure nanoscale and nano-submicron hybrid scales of titanium surface features were sufficient for activating integrin-ligand proteins interactions through the α integrin subunits, only nano-submicron hybrid titanium surface features significantly accelerated subsequent osteoblast differentiation of primary mouse bone marrow stromal cells after 2 weeks. In addition, live cell analysis of human bone marrow mesenchymal stem cells on transparent titanium demonstrated rapid cytoskeletal re-organization on the nanoscale surface features, which ultimately induced higher expression of osteoblast phenotype genes after 3 weeks. © 2012 Elsevier Ltd.

Sun B.,University of Technology, Sydney | Chen Z.,University of Wollongong | Kim H.-S.,Korea Electrotechnology Research Institute | Ahn H.,Gyeongsang National University | Wang G.,University of Technology, Sydney
Journal of Power Sources | Year: 2011

MnO/C core-shell nanorods were synthesized by an in situ reduction method using MnO2 nanowires as precursor and block copolymer F127 as carbon source. Field emission scanning electron microscopy and transmission electron microscopy analysis indicated that a thin carbon layer was coated on the surfaces of the individual MnO nanorods. The electrochemical properties were evaluated by cyclic voltammetry and galvanostatic charge-discharge techniques. The as-prepared MnO/C core-shell nanorods exhibit a higher specific capacity than MnO microparticles as anode material for lithium ion batteries. © 2010 Elsevier B.V. All rights reserved.

Tantry U.S.,Sinai Hospital of Baltimore | Bonello L.,Aix - Marseille University | Aradi D.,Heart Center Balatonfured | Price M.J.,Scripps Research Institute | And 19 more authors.
Journal of the American College of Cardiology | Year: 2013

Dual antiplatelet therapy with aspirin and a P2Y12 receptor blocker is a key strategy to reduce platelet reactivity and to prevent thrombotic events in patients treated with percutaneous coronary intervention. In an earlier consensus document, we proposed cutoff values for high on-treatment platelet reactivity to adenosine diphosphate (ADP) associated with post-percutaneous coronary intervention ischemic events for various platelet function tests (PFTs). Updated American and European practice guidelines have issued a Class IIb recommendation for PFT to facilitate the choice of P2Y 12 receptor inhibitor in selected high-risk patients treated with percutaneous coronary intervention, although routine testing is not recommended (Class III). Accumulated data from large studies underscore the importance of high on-treatment platelet reactivity to ADP as a prognostic risk factor. Recent prospective randomized trials of PFT did not demonstrate clinical benefit, thus questioning whether treatment modification based on the results of current PFT platforms can actually influence outcomes. However, there are major limitations associated with these randomized trials. In addition, recent data suggest that low on-treatment platelet reactivity to ADP is associated with a higher risk of bleeding. Therefore, a therapeutic window concept has been proposed for P2Y 12 inhibitor therapy. In this updated consensus document, we review the available evidence addressing the relation of platelet reactivity to thrombotic and bleeding events. In addition, we propose cutoff values for high and low on-treatment platelet reactivity to ADP that might be used in future investigations of personalized antiplatelet therapy. © 2013 by the American College of Cardiology Foundation.

Hahn J.-Y.,Sungkyunkwan University | Song Y.B.,Sungkyunkwan University | Kim E.K.,Sungkyunkwan University | Yu C.W.,Seoul National University | And 14 more authors.
Circulation | Year: 2013

BACKGROUND - : Ischemic postconditioning has been reported to reduce infarct size in patients with ST-segment-elevation myocardial infarction. However, cardioprotective effects of postconditioning have not been demonstrated in a large-scale trial. METHODS AND RESULTS - : We performed a multicenter, prospective, randomized, open-label, blinded end-point trial. A total of 700 patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment-elevation myocardial infarction within 12 hours after symptom onset were randomly assigned to the postconditioning group or to the conventional primary PCI group in a 1:1 ratio. Postconditioning was performed immediately after restoration of coronary flow as follows: The angioplasty balloon was positioned at the culprit lesion and inflated 4 times for 1 minute with low-pressure (<6 atm) inflations, each separated by 1 minute of deflation. The primary end point was complete ST-segment resolution (percentage resolution of ST-segment elevation >70%) measured at 30 minutes after PCI. Complete ST-segment resolution occurred in 40.5% of patients in the postconditioning group and 41.5% of patients in the conventional PCI group (absolute difference, -1.0%; 95% confidence interval, -8.4 to 6.4; P=0.79). The rate of myocardial blush grade of 0 or 1 and the rate of major adverse cardiac events (a composite of death, myocardial infarction, severe heart failure, or stent thrombosis) at 30 days did not differ significantly between the postconditioning group and the conventional PCI group (17.2% versus 22.4% [P=0.20] and 4.3% versus 3.7% [P=0.70], respectively). CONCLUSION - : Ischemic postconditioning did not improve myocardial reperfusion in patients with ST-segment-elevation myocardial infarction undergoing primary PCI with current standard practice. CLINICAL TRIAL REGISTRATION - : URL: Unique identifier: NCT00942500. © 2013 American Heart Association, Inc.

Lee Y.-H.,Kyungpook National University | Yuk H.J.,Gyeongsang National University | Park K.-H.,Gyeongsang National University | Bae Y.-S.,Kyungpook National University
Food Chemistry | Year: 2013

An inhibitor of the protein kinase CKII (CKII) was purified from leaves of Glycine max (L.) Merrill and was identified as coumestrol by structural analysis. Coumestrol inhibited the phosphotransferase activity of CKII toward β-casein, with an IC50 of about 5 lM. It acted as a competitive inhibitor with respect to ATP as a substrate, with an apparent Ki value of 7.67 lM. Coumestrol at 50 lM resulted in 50% and 30% growth inhibition of human breast cancer MCF-7 and colorectal cancer HCT116 cells, respectively. Coumestrol promoted senescence through the p53-p21Cip1/WAF1 pathway by inducing reactive oxygen species (ROS) production in MCF-7 and HCT116 cells. The ROS scavenger N-acetyl-L-cysteine (NAC), NADPH oxidase inhibitor apocynin and p22phox siRNA almost completely abolished this event. Overex-pression of CKIIa antagonised cellular senescence mediated by coumestrol, indicating that this compound induced senescence via a CKII-dependent pathway. Since senescence is an important tumour suppression process in vivo, these results suggest that coumestrol can function by inhibiting oncogenic disease, at least in part, through CKII inhibition-mediated cellular senescence. © 2013 Elsevier Ltd. All rights reserved.

Kim M.-K.,Gyeongsang National University | Flynn P.J.,University of Notre Dame
2014 IEEE Winter Conference on Applications of Computer Vision, WACV 2014 | Year: 2014

This paper proposes a novel finger-knuckle-print (FKP) verification method based on vector consistency among corresponding interest points (CIPs) detected from aligned finger images. We used two different approaches for reliable detection of CIPs; one method employs SIFT features and captures gradient directionality, and the other method employs phase correlation to represent the intensity field surrounding an interest point. The consistency of interframe displacements between pairs of matching CIPs in a match pair is used as a matching score. Such displacements will show consistency in a genuine match but not in an impostor match. Experimental results show that the proposed approach is effective in FKP verification. © 2014 IEEE.

Kwon O.-Y.,Gyeongsang National University | Park S.-P.,Kyungpook National University
Epilepsy and Behavior | Year: 2011

The quality of life (QOL) of individuals with well-controlled epilepsy (WCE) is often not considered. We therefore investigated predictors determining QOL in patients who had been seizure free at least 1. year on stable antiepileptic drug (AED) monotherapy. They were asked to complete self-report health questionnaires, including the Beck Depression Inventory (BDI), Adverse Event Profile (AEP), and Quality of Life in Epilepsy Inventory-31 (QOLIE-31). We looked for predictors of QOLIE-31 scores among the various demographic, socioeconomic, and clinical factors and BDI, and AEP scores. Depression symptoms were manifested by 18.7% of patients. People with depression symptoms were more likely to report adverse events than those without depression symptoms. The strongest predictor of QOL was BDI score, followed by AEP total score, years of education, and income. BDI score had 3.37 times the effect of AEP total score. In conclusion, QOL of patients with WCE is determined mainly by depressive symptoms. © 2011 Elsevier Inc.

Jeong Y.N.,Chonnam National University | Choi M.Y.,Gyeongsang National University | Choi H.C.,Chonnam National University
Electrochimica Acta | Year: 2012

Pt- and Pd-decorated carbon nanotubes (CNTs) have been prepared by diimide-activated amidation, an approach that avoids the harmful products of conventional SOCl 2 treatment. In this study, N,N′- dicyclohexylcarbodiimide (DCC) was used as a coupling agent for the formation of an amide linkage. According to ICP measurements, the resulting materials consist of 7.1 wt.% loaded Pt and 8.6 wt.% loaded Pd. The TEM images show that size-similar and quasi-spherical nanoparticles are highly dispersed along the entire CNT walls. The prepared Pt-CNT exhibited an especially high oxidation current toward methanol, formic acid, and formaldehyde compared with that of the pristine CNT and a Pt/CNT mixture (10 wt.% Pt). Furthermore, the Pd-CNT displayed higher activity toward H 2O 2 reduction than that of the reference systems. The better catalytic activities can be explained by the high electrochemically active surface area that resulted from the smaller size and excellent dispersion of metal nanoparticles on CNT. These results demonstrate the DCC-activated amidation to be a very effective and useful way to tune size and disperse metal species in metal-decorated CNTs, markedly improving their catalytic activity. © 2011 Elsevier Ltd. All rights reserved.

Young S.,Korea University of Technology and Education | Nam T.-H.,Gyeongsang National University
Materials Research Bulletin | Year: 2014

Inhomogeneous deformation is one of the essential characters of shape memory alloy. Specimen is composed of many variants which have different strain. There exist a phase interface between two different phases and its mobility will depend on several factors such as curvature and orientation of the interface. The shape memory alloys exhibit hysteresis and one of the main reasons to cause hysteretic behavior is thought to be the internal inhomogeneity. It is thought that the phase interfaces display irregularities in the motion and the resultant state is metastable one which requires a very long relaxation time. In this work, spatially inhomogeneous frictional force to the volume change of the variants is assumed to account for the irregular behavior of the phase transformation. Its effect on the production of the macroscopic strain of a shape memory alloy is investigated using finite element calculation. Load-biased thermal cycling of a shape memory alloy is considered. The numerical result is compared with experimental data of Ti-44.5Ni-5Cu-0.5V (at.%) alloy. A better agreement is obtained for the experimental data when the inhomogeneous friction is assumed. © 2014 Elsevier Ltd. All rights reserved.

Endale M.,Kyungpook National University | Endale M.,Cincinnati Childrens Hospital Medical Center | Park S.-C.,Kyungpook National University | Kim S.,Gyeongsang National University | And 4 more authors.
Immunobiology | Year: 2013

Quercetin is a major bioflavonoid widely present in fruits and vegetables. It exhibits anti-inflammatory, anti-tumor, antioxidant properties and reduces cardiovascular disease risks. However, the molecular mechanism of action against inflammation in RAW 264.7 cells is only partially explored. Quercetin effect on LPS-induced gene and protein expressions of inflammatory mediators and cytokines were determined. Moreover, involvement of heme-oxygenase-1, protein kinases, adaptor proteins and transcription factors in molecular mechanism of quercetin action against inflammation were examined. Quercetin inhibited LPS-induced NO, PGE2, iNOS, COX-2, TNF-α, IL-1β, IL-6 and GM-CSF mRNA and protein expressions while it promoted HO-1 induction in a dose- and time-dependent manner. It also suppressed I-κB-phosphorylation, NF-κB translocation, AP-1 and NF-κB-DNA-binding and reporter gene transcription. Quercetin attenuated p38MAPK and JNK1/2 but not ERK1/2 activations and this effect was further confirmed by SB203580 and SP600125-mediated suppressions of HO-1, iNOS, and COX-2 protein expressions. Moreover, quercetin arrested Src, PI3K, PDK1 and Akt activation in a time- and dose-dependent manner, which was comparable to PP2 and LY294002 inhibition of Src, PI3K/Akt and iNOS expressions. Quercetin further arrested Src and Syk tyrosine phosphorylations and their kinase activities followed by inhibition of PI3K tyrosine phosphorylation. Moreover, quercetin disrupted LPS-induced p85 association to TLR4/MyD88 complex and it then limited activation of IRAK1, TRAF6 and TAK1 with a subsequent reduction in p38 and JNK activations, and suppression in IKKα/β-mediated I-κB phosphorylation. Quercetin limits LPS-induced inflammation via inhibition of Src- and Syk-mediated PI3K- (p85) tyrosine phosphorylation and subsequent TLR4/MyD88/PI3K complex formation that limits activation of downstream signaling pathways. © 2013 Elsevier GmbH.

Young S.-Y.,Korea University of Technology and Education | Nam T.-H.,Gyeongsang National University
Journal of Alloys and Compounds | Year: 2013

This paper presents a three-dimensional calculation model for martensitic transformation and the numerical results were compared with experimental load-biased thermal cycling data of Ti-35Ni-15Cu (at%) shape memory alloy. Our new model accounts for the self-accommodation part of the variants separately in addition to the conventional individual variants. Thermodynamic driving force for a transformation between bistable states was provided in terms of a potential energy of each variant. Transformation kinetic parameters were applied differentially to the self-accommodation and the individual variants. By this approach, interplay between thermodynamics and kinetics of the self-accommodation and the individual variants could be successfully captured. The model has predicted the experimental result more accurately than the model without the self-accommodation part. © 2012 Elsevier B.V.

Lee Y.,Gyeongsang National University | Lee S.,Gyeongsang National University | Carello C.,University of Connecticut | Turvey M.T.,University of Connecticut
Journal of Experimental Psychology: Human Perception and Performance | Year: 2012

For skills that involve hitting a target, subsequent judgments of target size correlate with prior success in hitting that target. We used an archery context to examine the judgment-success relationship with varied target sizes in the absence of explicit knowledge of results. Competitive archers shot at targets 50 m away that varied in size among five diameters. Immediately after the arrow's release, its flight and landing were occluded and archers chose which of 18 miniature targets looked most like the distal target. Greater apparent size correlated with higher accuracy. In a second experiment, nonarchers merely aimed the bow (without an arrow) at varied targets. Apparent size was larger when the bow arm was stabilized than when it was not. Archery is seemingly an instance of affordance-based control: For an archer, the affordance of the target is the "hitableness" of its central regions, a property inclusive of his or her momentary, and perceptible, archery form. © 2012 American Psychological Association.

Park K.-W.,Gyeongsang National University | Seo H.J.,Chonnam National University | Kwon O.-Y.,Chonnam National University
Microporous and Mesoporous Materials | Year: 2014

Mesoporous silica-pillared H+-titanosilicate (SPT) was prepared by hydrolysis of tetraethylorthosilicate using dodecylamine as the template and catalyst in the interlayer space of H+-titanosilicate (H 4Ti2Si8O22·4H2O). SPT exhibited regular gallery height of 3.60 nm, narrow pore distributions of 3.1-3.4 nm, and a large specific surface area of 435-542 m2/g. The sharpness of the SPT 2d00l peak was well preserved even after heating for 5 h at 800 °C in air. Ni/STP and Rh/SPT loaded with 5 wt% metal were examined for partial oxidation of methane (POM) at 700 °C. Ni/SPT and Rh/SPT maintained stable activity for almost 100 h on stream. CH4 conversion (>90%) and H2 yield (>90%) over Ni/SPT and Rh/SPT were higher than that (>80%) of commercial Rh/Al2O3 (loaded with 5 wt% metal). CO yield was very low due to carbon cocking from the formation of carbon nanotubes. Transmission electron microscopy images of the STP catalysts exhibited uniform spacing between the layers even after catalysis and uniform dispersion of metal particles. These observations indicate the unique properties of an SPT catalyst such as the existence of five-coordinated titanium(VI) as an oxidation site, uniform dispersion of metal, ordered pore structure and heat stability, resulting in good performance during POM. © 2014 Published by Elsevier Inc.

Chen J.,Neuroscience and Early Discovery | Kang D.,Rosalind Franklin University of Medicine and Science | Kang D.,Gyeongsang National University | Xu J.,Abbvie Inc. | And 6 more authors.
Nature Communications | Year: 2013

TRPA1 is an ion channel and has been proposed as a thermosensor across species. In invertebrate and ancestral vertebrates such as fly, mosquito, frog, lizard and snakes, TRPA1 serves as a heat receptor, a sensory input utilized for heat avoidance or infrared detection. However, in mammals, whether TRPA1 is a receptor for noxious cold is highly controversial, as channel activation by cold was observed by some groups but disputed by others. Here we attribute the discrepancy to species differences. We show that cold activates rat and mouse TRPA1 but not human or rhesus monkey TRPA1. At the molecular level, a single residue within the S5 transmembrane domain (G878 in rodent but V875 in primate) accounts for the observed difference in cold sensitivity. This residue difference also underlies the species-specific effects of menthol. Together, our findings identify the species-specific cold activation of TRPA1 and reveal a molecular determinant of cold-sensitive gating. © 2013 Macmillan Publishers Limited.

Kim S.M.,Korea Advanced Institute of Science and Technology | Kim S.M.,KTH Royal Institute of Technology | Jung B.C.,Gyeongsang National University | Choi W.,Korea Advanced Institute of Science and Technology | Sung D.K.,Korea Advanced Institute of Science and Technology
IEEE Transactions on Vehicular Technology | Year: 2013

In this paper, we investigate the effects of heterogeneous mobility on rate adaptation and user scheduling in cellular networks with hybrid automatic repeat request (HARQ). To this end, we first show the performance tradeoff between two extreme scheduling criteria: retransmission-oriented scheduling (ROS) and mixed scheduling (MS) criteria over time-correlated Rayleigh fading channels. Then, we propose an ROS-based joint rate adaptation and user scheduling (JRAUS) policy for cellular networks and compare it with the conventional and reference JRAUS policies. We also evaluate the system-level performance of the proposed ROS-based JRAUS policy in various user distribution and mobility scenarios. In particular, in an asymmetric user distribution and heterogeneous mobility scenario, which is the most general one in practice, the proposed JRUAS policy yields a throughput gain of 49% and a fairness gain of 155% over the conventional JRAUS policies. In this paper, we find that the rate adaptation is significant not only in a single point-to-point link but in multiuser systems with heterogeneous mobility as well. © 1967-2012 IEEE.

Ahn C.-B.,Chonnam National University | Kim J.-G.,Gyeongsang National University | Je J.-Y.,Chonnam National University
Food Chemistry | Year: 2014

Pectoral fin protein from salmon processing byproduct was hydrolyzed using Alcalase, Flavourzyme, Neutrase, pepsin, Protamex, and trypsin, and the peptic hydrolysate showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Antioxidant peptide was purified using consecutive chromatography. The purified antioxidant peptide was identified to be Phe-Leu-Asn-Glu-Phe-Leu-His-Val with molecular weight of 1018.48 Da by time of flight-mass spectrometry/mass spectrometry (TOF-MS) analysis. The IC 50 values against DPPH and 2,2-azino-bis(3-ethylbenzthiazoline)-6- sulfonic acid (ABTS) cation radical scavenging activity were 486 and 152 μM, respectively, and the octapeptide showed strong ferric reducing power. In addition, the octapeptide showed significant (p < 0.05) protection ability against hydroxyl radical-induced DNA damage and hydrogen peroxide-induced hepatic damage in Chang liver cells. Taken together, the pectoral fin protein hydrolysate and/or its active peptides may be useful ingredients in functional food. © 2013 Elsevier Ltd. All rights reserved.

Kim J.,KAIST | Kwon S.,KAIST | Kim S.H.,Chonnam National University | Lee C.-K.,Korea Basic Science Institute | And 5 more authors.
Journal of the American Chemical Society | Year: 2012

In nature, complex and well-defined structures are constructed by the self-assembly of biomolecules. It has been shown that β-peptide foldamers can mimic natural peptides and self-assemble into three-dimensional molecular architectures thanks to their rigid and predictable helical conformation in solution. Using shorter foldamers, which can be prepared more easily than longer ones, to form such architectures is highly desirable, but shorter foldamers have been overlooked due to the seemingly inferior number of intramolecular hydrogen bonds to stabilize a folded state in solution. Here we report that a β-peptide tetramer, although it lacks full helical propensity in solution, does self-assemble to form well-defined microtubes with rectangular cross-section by evaporation-induced self-assembly. © 2012 American Chemical Society.

Wang G.,University of Technology, Sydney | Liu H.,University of Wollongong | Horvat J.,University of Wollongong | Wane B.,University of Technology, Sydney | And 3 more authors.
Chemistry - A European Journal | Year: 2010

Highly ordered mesoporous Co3O4 nanostructures were prepared using KIT-6 and SBA-15 silica as hard templates. The structures were confirmed by small angle X-ray diffraction, high resolution transmission electron microscopy, and N2 adsorption-desorption isotherm analysis. Both KIT-6 cubic and SBA-15 hexagonal mesoporous Co3O4 samples exhibited a low Néel temperature and bulk antiferromagnetic coupling due to geometric confinement of antiferromagnetic order within the nanoparticles. Mesoporous Co3O4 electrode materials have demonstrated the high lithium storage capacity of more than 1200 mAhg -1 with an excellent cycle life. They also exhibited a high specific capacitance of 370 Fg-1 as electrodes in supercapacitors. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim K.H.,Chonnam National University | Kim S.H.,Chonnam National University | Park S.,Gyeongsang National University | Kim J.N.,Chonnam National University
Tetrahedron | Year: 2011

Various indane and cyclobuta[a]indene derivatives were synthesized by palladium-catalyzed cyclization of homoallylic alcohol derivatives prepared from Baylis-Hillman adducts. Especially, cyclobuta[a]indene derivative was synthesized stereoselectively by palladium-catalyzed 5-exo-trig/4-exo-trig cascade cyclization, albeit in moderate yield. The Z isomer was formed exclusively in the presence of Et3N by usual Heck-type carbopalladation process while E isomer with Cs2CO3 most likely by a concerted metalation/deprotonation (CMD) process. © 2011 Published by Elsevier Ltd.

Jin M.,Kyungpook National University | Kim J.-H.,Kyungpook National University | Jang E.,Kyungpook National University | Lee Y.M.,Kyungpook National University | And 5 more authors.
Journal of Cerebral Blood Flow and Metabolism | Year: 2014

Lipocalin-2 (LCN2) is a secreted protein of the lipocalin family, but little is known about the expression or the role of LCN2 in the central nervous system. Here, we investigated the role of LCN2 in ischemic stroke using a rodent model of transient cerebral ischemia. Lipocalin-2 expression was highly induced in the ischemic brain and peaked at 24 hours after reperfusion. After transient middle cerebral artery occlusion, LCN2 was predominantly expressed in astrocytes and endothelial cells, whereas its receptor (24p3R) was mainly detected in neurons, astrocytes, and endothelial cells. Brain infarct volumes, neurologic scores, blood-brain barrier (BBB) permeabilities, glial activation, and inflammatory mediator expression were significantly lower in LCN2-deficient mice than in wild-type animals. Lipocalin-2 deficiency also attenuated glial neurotoxicity in astrocyte/neuron cocultures after oxygen-glucose deprivation. Our results indicate LCN2 has a critical role in brain injury after ischemia/reperfusion, and that LCN2 may contribute to neuronal cell death in the ischemic brain by promoting neurotoxic glial activation, neuroinflammation, and BBB disruption. © 2014 ISCBFM.

Yoon H.,Chonnam National University | Yoon H.,Gyeongsang National University | Kim D.H.,University of Pennsylvania
International Journal of Clinical Pharmacy | Year: 2013

Case We describe here a rare case in which valproic acid (VPA) levels were affected by ertapenem but not by meropenem even though ertapenem and meropenem are in the same carbapenem class. A 68-year-old Filipino male treated with valproate for epilepsy and ertapenem for an infectious disease had decreased VPA levels during the first day of ertapenem therapy. His VPA level increased soon after terminating ertapenem therapy. Two types of carbapenems had different drug reactions with concomitant use of VPA in this patient. Conclusions Closer monitoring of VPA concentrations are necessitated using carbapenems for treating infection in patients being administered VPA. Another option is the use of anti-epileptic drugs other than VPA if concomitant use with a carbapenem is warranted. © 2013 Springer Science+Business Media Dordrecht.

Yoo S.-J.,Gyeongsang National University | Yun H.-J.,Gyeongsang National University | Kang I.,Gyeongsang National University | Thangaraju K.,Gandhigram Rural University | And 2 more authors.
Journal of Materials Chemistry C | Year: 2013

A highly efficient new benzoimidazole phosphine oxide based electron transporting material, bis(1-phenyl-1H-benzo[d]imidazole)phenylphosphine oxide (BIPO), was designed, synthesized by condensation, nucleophilic substitution and oxidation reactions, and confirmed using various spectroscopic studies. It shows a thermal stability (ΔT5%) of 451 °C with a glass transition temperature of 129 °C from the thermogravimetric analysis and differential scanning calorimetry studies. BIPO used as an efficient electron transport layer (ETL) in a green emitting phosphorescent organic light emitting diode, ITO/4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (30 nm)/4,4′,4′′-tris(carbazole-9-yl)triphenylamine 10 nm)/(4,4′-N,N′-dicarbazole)biphenyl (CBP) host doped with Ir(ppy)3 dopant (5%) (30 nm)/ETL (40 nm)/LiF (1 nm)/Al (100 nm), serves as an effective hole-blocking material and improves the charge balance in the device, resulting in higher device efficiencies of 22.19%, 68.3 cd A -1 and 24.4 lm W-1 with a maximum luminance of 72 080 cd m-2 compared to those (17.03%, 52.0 cd A-1 and 20.9 lm W-1 with a maximum luminance of 33 490 cd m-2) of a device using a widely used ETL, 1,3,5-tris(m-pyrid-3-yl-phenyl)benzene. These results show that the new BIPO ETL could be very useful in efficient organic light emitting diodes. © 2013 The Royal Society of Chemistry.

Ha Y.,Gyeongsang National University | Choi E.,Kyungpook National University | Seo Y.,Gyeongnam National University of Science and Technology | Kim T.-G.,Inje University
Journal of School Health | Year: 2013

Background: This study identified relationships among subjective social status (SSS), weight perception, weight control behaviors, and weight status in Korean adolescents using nationally representative data collected from the 2009 Korea Youth Risk Behaviors Web-Based Survey. Methods: Data from 67,185 students aged 12-18years were analyzed. Relationships among SSS, weight perception, and weight control behaviors in boys and girls were examined using chi-square. Logistic regression analysis was performed with adjusting school grade and place of residence to assess potential associations between multiple variables and overweight students. RESULTS: Lower SSS was associated with a significant risk of being overweight in girls, but not in boys. Of particular interest, overestimation and underestimation coexist within boys, whereas girls predominantly tended to overestimate their weight status. Inaccurate weight perception and unhealthy weight control behaviors were significantly associated with the risk of being overweight in both boys and girls. Conclusions: Considering the results of this study showing sex differences in weight perception and weight control behaviors, sex-specific overweight prevention programs are needed to achieve accurate weight perception and healthy weight control behaviors. © 2013, American School Health Association.

Kim E.S.,Chonnam National University | Kim K.H.,Chonnam National University | Park S.,Gyeongsang National University | Kim J.N.,Chonnam National University
Tetrahedron Letters | Year: 2010

An efficient synthesis of dihydroindenofurans was carried out starting from the Baylis-Hillman adducts via a Pd-catalyzed 5-endo-trig-carbopalladation and enolate O-alkylation cascade as a key step. This is the first example of enolate O-alkylation with a C(sp3)-bound palladium intermediate. © 2010 Elsevier Ltd. All rights reserved.

Kwon O.-Y.,Gyeongsang National University | Park S.-P.,Kyungpook National University
Seizure | Year: 2016

Purpose Fatigue impairs the quality of life (QOL) of epilepsy patients, but few studies have investigated this issue and no systematic analysis of the predictors of fatigue in epilepsy patients has been performed. Thus, we investigated the degree and predictors of fatigue in epilepsy patients. Methods We enrolled 270 consecutive adult patients with epilepsy and categorized them into three subgroups: uncontrolled epilepsy (UCE), well-controlled epilepsy (WCE), and poorly controlled epilepsy (PCE). All subjects were asked to complete the Korean versions of the Fatigue Severity Scale (K-FSS), the Neurological Disorders Depression Inventory for Epilepsy (K-NDDI-E), the Generalized Anxiety Disorder-7 (K-GAD-7) scale, and the short forms of the Patient-Reported Outcomes Measurement Information System Sleep-Related Impairment (PROMIS-SRI) and Sleep Disturbance (PROMIS-SD) scales. Additionally, 200 normal control subjects who completed the K-FSS, K-NDDI-E, and K-GAD-7 measures were included. The K-FSS scores of the epilepsy subgroups and the control group were compared, and stepwise multiple regression analysis was performed to identify predictors of high scores on the K-FSS among epilepsy patients. Results The K-FSS, K-NDDI-E, and K-GAD-7 scores were higher in the epilepsy patients than in the controls. The K-FSS scores of the UCE subgroup, but not of the PCE and WCE subgroups, were higher than those of the control group. K-FSS scores of epilepsy patients were predicted by PROMIS-SRI and K-NDDI-E scores. Conclusions Fatigue was more severe in epilepsy patients than in healthy controls without epilepsy, especially when seizures were not controlled. Sleep-related impairments and depression aggravated fatigue in epilepsy patients. © 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Yin Y.,East China Institute of Technology | Jun Y.B.,Gyeongsang National University | Zhan J.,Hubei University for Nationalities
Computers and Mathematics with Applications | Year: 2011

Xu et al. introduced the concept of vague soft sets, which is an extension to the soft set and the vague set. In this paper, we apply the concept of vague soft sets to hemiring theory. The notion of (∈,∈∨q)-vague (soft) left h-ideals of a hemiring is introduced and some related properties are investigated. © 2011 Elsevier Ltd. All rights reserved.

Xu J.,Indiana University Bloomington | Kim J.,Gyeongsang National University | Koestler B.J.,Michigan State University | Choi J.-H.,Indiana University Bloomington | And 3 more authors.
Molecular Microbiology | Year: 2013

Many bacteria colonize surfaces and transition to a sessile mode of growth. The plant pathogen Agrobacterium tumefaciens produces a unipolar polysaccharide (UPP) adhesin at single cell poles that contact surfaces. Here we report that elevated levels of the intracellular signal cyclic diguanosine monophosphate (c-di-GMP) lead to surface-contact-independent UPP production and a red colony phenotype due to production of UPP and the exopolysaccharide cellulose, when A.tumefaciens is incubated with the polysaccharide stain Congo Red. Transposon mutations with elevated Congo Red staining identified presumptive UPP-negative regulators, mutants for which were hyperadherent, producing UPP irrespective of surface contact. Multiple independent mutations were obtained in visN and visR, activators of flagellar motility in A.tumefaciens, now found to inhibit UPP and cellulose production. Expression analysis in a visR mutant and isolation of suppressor mutations, identified three diguanylate cyclases inhibited by VisR. Null mutations for two of these genes decrease attachment and UPP production, but do not alter cellular c-di-GMP levels. However, analysis of catalytic site mutants revealed their GGDEF motifs are required to increase UPP production and surface attachment. Mutations in a specific presumptive c-di-GMP phosphodiesterase also elevate UPP production and attachment, consistent with c-di-GMP activation of surface-dependent adhesin deployment. © 2013 John Wiley & Sons Ltd.

Nam T.-H.,Gyeongsang National University | Kim Y.-W.,Keimyung University
Intermetallics | Year: 2010

The shape memory alloy ribbons of Ti50Ni15Cu 35 had been fabricated by two rapid solidification processes of melt spinner and melt overflow to achieve different rapidly solidified structures. The ribbon fabricated by the melt spinner was an amorphous and any martensitic transformations occurred in the crystallized ribbon due to the formation of an equilibrium intermetallic phase (Cu4Ti3). However, the microstructure of the ribbon prepared by the melt overflow exhibited columnar grains normal to the ribbon surface. X-ray diffraction analysis showed that one-step martensitic transformation of B2-B19 occurred in the ribbon. According to the DSC analysis, it was known that the martensitic transformation temperature of B2 → B19 was 71.2 °C. During thermal cyclic deformation with the applied stress of 120 MPa, transformation hysteresis and elongation associated with the B2-B19 transformation were observed to be 4.6 °C and 1.68%, respectively, in the Ti50Ni15Cu35 alloy. It is considered that these shape memory characteristics were ascribed to solid-solution strengthening by the supersaturation of excess Cu content. © 2010 Elsevier Ltd. All rights reserved.

Yin Y.,East China Institute of Technology | Li H.,Zhoukou Normal University | Jun Y.B.,Gyeongsang National University
Computers and Mathematics with Applications | Year: 2012

Maji et al. introduced the concept of intuitionistic fuzzy soft sets which is a generalization of fuzzy soft sets and standard soft sets. In this paper, we further discuss the operation properties and algebraic structure of intuitionistic fuzzy soft sets. The lattice structures of intuitionistic fuzzy soft sets are derived. The notions of (γ,δ)-intuitionistic fuzzy soft equalities are introduced and their basic properties are investigated. The relationships between (γ,δ)-intuitionistic fuzzy soft equalities and soft equalities introduced by Qin and Hong are developed. The notion of a mapping on intuitionistic fuzzy soft classes is introduced and several properties of the image and inverse image of intuitionistic fuzzy soft sets are presented. © 2012 Elsevier Ltd. All rights reserved.

Kwon O.-Y.,Gyeongsang National University | Park S.-P.,Kyungpook National University
Journal of Clinical Neurology (Korea) | Year: 2014

Many recent epidemiological studies have found the prevalence of depression and anxiety to be higher in people with epilepsy (PWE)than in people without epilepsy. Furthermore, people with depression or anxiety have been more likely to suffer from epilepsy than those without depression or anxiety. Almost one-third of PWE suffer from depression and anxiety, which is similar to the prevalence of drug-refractory epilepsy. Various brain areas, including the frontal, temporal, and limbic regions, are associated with the biological pathogenesis of depression in PWE. It has been suggested that structural abnormalities, monoamine pathways, cerebral glucose metabolism, the hypothalamic-pituitary-adrenal axis, and interleukin-1b are associated with the pathogenesis of depression in PWE. The amygdala and the hippocampus are important anatomical structures related to anxiety, and γ-aminobutyric acid and serotonin are associated with its pathogenesis. Depression and anxiety may lead to suicidal ideation or attempts and feelings of stigmatization. These experiences are also likely to increase the adverse effects associated with antiepileptic drugs and have been related to poor responses to pharmacological and surgical treatments. Ultimately, the quality of life is likely to be worse in PWE with depression and anxiety than in PWE without these disorders, which makes the early detection and appropriate management of depression and anxiety in PWE indispensable. Simple screening instruments may be helpful for in this regard, particularly in busy epilepsy clinics. Although both medical and psychobehavioral therapies may ameliorate these conditions, randomized controlled trials are needed to confirm that. © 2014 Korean Neurological Association.

Wang B.,University of Wollongong | Wang B.,University of Technology, Sydney | Park J.,Gyeongsang National University | Wang C.,University of Technology, Sydney | And 3 more authors.
Electrochimica Acta | Year: 2010

Mn3O4/graphene nanocomposites were synthesized by mixing graphene suspension in ethylene glycol with MnO2 organosol, followed by subsequent ultrasonication processing and heat treatment. The as-prepared product consists of nanosized Mn3O4 particles homogeneously distributed on graphene nanosheets, which has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis. Atomic force microscope analysis further identified the distribution of dense Mn3O4 nanoparticles on graphene nanosheets. When used as electrode materials in supercapacitors, Mn3O 4/graphene nanocomposites exhibited a high specific capacitance of 175 F g-1 in 1 M Na2SO4 electrolyte and 256 F g-1 in 6 M KOH electrolyte, respectively. The enhanced supercapacitance of Mn3O4/graphene nanocomposites could be ascribed to both electrochemical contributions of Mn3O4 nanoparticles, functional groups attached to graphene nanosheets, and significantly increased specific surface area. © 2010 Elsevier Ltd. All rights reserved.

Park J.,Kyungpook National University | Min J.-S.,Kyungpook National University | Kim B.,Kyungpook National University | Chae U.-B.,Kyungpook National University | And 5 more authors.
Neuroscience Letters | Year: 2015

Activation of microglia cells in the brain contributes to neurodegenerative processes promoted by many neurotoxic factors such as pro-inflammatory cytokines and nitric oxide (NO). Reactive oxygen species (ROS) actively affect microglia-associated neurodegenerative diseases through their role as pro-inflammatory molecules and modulators of pro-inflammatory processes. Although the ROS which involved in microglia activation are thought to be generated primarily by NADPH oxidase (NOX) and involved in the immune response, mitochondrial ROS have also been proposed as important regulators of the inflammatory response in the innate immune system. However, the role of mitochondrial ROS in microglial activation has yet to be fully elucidated. In this study, we demonstrate that inhibition of mitochondrial ROS by treatment with Mito-TEMPO effectively suppressed the level of mitochondrial and intracellular ROS. Mito-TEMPO treatment also significantly prevented LPS-induced increase in the TNF-α, IL-1β, IL-6, iNOS and Cox-2 in BV-2 and primary microglia cells. Furthermore, LPS-induced suppression of mitochondrial ROS generation not only affected LPS-stimulated activation of MAPKs, including ERK, JNK, and p38, but also regulated IκB activation and NF-κB nuclear localization. These results indicate that mitochondria constitute a major source of ROS generation in LPS-mediated activated microglia cells. Additionally, suppression of LPS-induced mitochondrial ROS plays a role in modulating the production of pro-inflammatory mediators by preventing MAPK and NF-κB activation in microglia cells. Our findings suggest that a potential strategy in the development of therapy for inflammation-associated degenerative neurological diseases involves targeting the regulation of mitochondrial ROS in microglial cells. © 2014 Elsevier Ireland Ltd.All rights reserved.

Hyun T.K.,Gyeongsang National University | Kim H.-C.,Research Institute for Hallasan | Kim J.-S.,Jeju National University
Industrial Crops and Products | Year: 2014

The present study was conducted to evaluate the antioxidant, antimicrobial, and antidiabetic activities of methanol extract of Thymus quinquecostatus Celak and those of its partitioned fractions, including hexane, ethyl acetate, n-butanol, and aqueous. The antioxidant activities of the TQC extract were measured by 1,1-dephenyl-2-picryl-hydrazyl free radical scavenging and a reducing power assay. The antidiabetic activity was evaluated by α-glucosidase and α-amylase inhibition assays. The results suggested that the ethyl acetate (EtOAc) fraction of the MeOH crude extract possessed strong antioxidant activity and capacity. In addition, the EtOAc fraction showed remarkable antimicrobial activity against Kocuria rhizophila (MIC = 63 μg/ml) and Staphylococcus epidermidis (MIC = 63 μg/ml). The findings also indicated that the MeOH crude extract and its EtOAc fraction contained strong antidiabetic activity. HPLC analysis identified (-)-catechin, chlorogenic acid, rutin, and rosmarinic acid as the active compounds in the TQC extract. The α-glucosidase inhibitory activity in the hexane fraction was positively associated with the amount of thymol. Taken together, these results suggest that the TQC extract could be exploited as an ingredient in antioxidant and antidiabetic supplements and in drugs to treat infectious diseases. © 2013 Elsevier B.V.

Young S.,Korea University of Technology and Education | Nam T.-H.,Gyeongsang National University
Materials Research Bulletin | Year: 2013

This paper presents a three-dimensional calculation model for martensitic phase transformation of shape memory alloy. Constitutive model based on thermodynamic theory was provided. The average behavior was accounted for by considering the volume fraction of each martensitic variant in the material. Evolution of the volume fraction of each variant was determined by a rate-dependent kinetic equation. We assumed that nucleation rate is faster for the self-accommodation than for the stress-induced variants. Three-dimensional finite element analysis was conducted and the results were compared with the experimental data of Ti-44.5Ni-5Cu-0.5 V (at.%) alloy under bias loading. © 2013 Elsevier Ltd. All rights reserved.

Kim J.-K.,Ulsan National Institute of Science and Technology | Kim J.-K.,Chalmers University of Technology | Aguilera L.,Chalmers University of Technology | Croce F.,University of Chieti Pescara | Ahn J.-H.,Gyeongsang National University
Journal of Materials Chemistry A | Year: 2014

Nano-sized γ-Fe2O3 was prepared by a minor modification method in combination with high energy ball milling, and a core-shell structure was designed using polypyrrole (PPy) by chemical polymerization. The structure and morphology of core-shell γ-Fe 2O3-PPy were investigated by XRD, FT-IR, SEM, and TEM. For solid-state batteries, PPy-Fe2O3 cells were fabricated with a gel polymer electrolyte prepared by an electrospinning process. The charge and discharge gravimetric capacities of all-solid-state batteries at the first cycle are 400 and 421 mA h g-1 and 220 and 221 mA h g -1 for 0.1 and 1 C-rates, respectively, which correspond to 760 and 800 mA h cm-3 and 418 and 420 mA h cm-3 of volumetric capacity. © The Royal Society of Chemistry.

Kwon O.-Y.,Gyeongsang National University | Park S.-P.,Kyungpook National University
Epilepsy and Behavior | Year: 2013

We investigated the frequency of affective symptoms in Korean adults with epilepsy who visited epilepsy clinics at two tertiary care hospitals and in healthy adults. We also examined the psychosocial impact of affective symptoms on people with epilepsy (PWE). Participants were asked to complete self-report questionnaires to assess depression and anxiety symptoms, felt stigma, suicidal ideation, and quality of life (QOL). Of 568 PWE, 30.5% exhibited affective symptoms. The frequencies of depression and anxiety symptoms were 27.8% and 15.3%, respectively, significantly higher than those in healthy controls. Those with poor seizure control were more likely to endorse affective symptoms at the time of study. The frequencies of felt stigma and suicidal ideation were higher in PWE with affective symptoms than in those without. Quality of life was impacted by affective symptoms, especially when depression and anxiety coexisted. Reducing affective symptoms by appropriate seizure control may ameliorate psychosocial problems in PWE. © 2012 Elsevier Inc.

Su D.,The Clean Tech Center | Horvat J.,University of Wollongong | Munroe P.,University of New South Wales | Ahn H.,Gyeongsang National University | And 2 more authors.
Chemistry - A European Journal | Year: 2012

Polyhedral magnetite nanocrystals with multiple facets were synthesised by a low temperature hydrothermal method. Atomistic simulation and calculations on surface attachment energy successfully predicted the polyhedral structure of magnetite nanocrystals with multiple facets. X-ray diffraction, field emission scanning electron microscopy, and high resolution transmission microscopy confirmed the crystal structure of magnetite, which is consistent with the theoretical modelling. The magnetic property measurements show the superspin glass state of the polyhedral nanocrystals, which could originate from the nanometer size of individual single crystals. When applied as an anode material in lithium ion cells, magnetite nanocrystals demonstrated an outstanding electrochemical performance with a high lithium storage capacity, a satisfactory cyclability, and an excellent high rate capacity. Crystal class: Polyhedral magnetite nanocrystals were prepared by a low temperature hydrothermal method, in which multiple facets can be theoretically predicated (see figure). The as-prepared magnetite nanocrystals show a magnetic property of superspin glass state, and demonstrated an outstanding electrochemical performance for lithium storage in lithium ion cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dassanayake M.,University of Illinois at Urbana - Champaign | Oh D.-H.,University of Illinois at Urbana - Champaign | Haas J.S.,University of Illinois at Urbana - Champaign | Hernandez A.,University of Illinois at Urbana - Champaign | And 13 more authors.
Nature Genetics | Year: 2011

Thellungiella parvula is related to Arabidopsis thaliana and is endemic to saline, resource-poor habitats, making it a model for the evolution of plant adaptation to extreme environments. Here we present the draft genome for this extremophile species. Exclusively by next generation sequencing, we obtained the de novo assembled genome in 1,496 gap-free contigs, closely approximating the estimated genome size of 140 Mb. We anchored these contigs to seven pseudo chromosomes without the use of maps. We show that short reads can be assembled to a near-complete chromosome level for a eukaryotic species lacking prior genetic information. The sequence identifies a number of tandem duplications that, by the nature of the duplicated genes, suggest a possible basis for T. parvula's extremophile lifestyle. Our results provide essential background for developing genomically influenced testable hypotheses for the evolution of environmental stress tolerance. © 2011 Nature America, Inc. All rights reserved.

Oh D.-H.,University of Illinois at Urbana - Champaign | Oh D.-H.,Gyeongsang National University | Dassanayake M.,University of Illinois at Urbana - Champaign | Bohnert H.J.,University of Illinois at Urbana - Champaign | And 3 more authors.
Genome Biology | Year: 2012

Extremophile plants thrive in places where most plant species cannot survive. Recent developments in high-throughput technologies and comparative genomics are shedding light on the evolutionary mechanisms leading to their adaptation. © 2012 BioMed Central Ltd.

Kim H.N.,Ewha Womans University | Lee E.-H.,Gyeongsang National University | Xu Z.,Ewha Womans University | Xu Z.,CAS Dalian Institute of Chemical Physics | And 4 more authors.
Biomaterials | Year: 2012

G-quadruplexes, formed of four stranded guanine bases stabilized by monovalent cations, serve important role in cancer cell growth and control gene expression in telomere. Since there are various types of quadruplex structures, rapid and simple screening methods with high selectivity, sensitivity and nontoxicity are required for understanding about the biological roles of quadruplex DNA as well as in designing therapeutics. Herein, we report a pyrene-imidazolium derivative, JY-1, which can with high selectivity recognize G-quadruplex using fluorescence and NMR spectroscopy. This is the first example based on the imidazolium derivative, which can detect the G-quadruplex directly to utilize the excimer/monomer emission change in pyrene fluorophore. The selectivity of strong binding to a specific sequence can allow for quadruplex sensing and the detection method presented here is very simple, using fluorescence and NMR study. Also, the groove binding characteristic of JY-1 to the G-quadruplex has a relatively low nonspecific toxicity and the structure-specific differences in fluorescent character between DNA duplex and G-quadruplex may offer more discovery and application in biological study. © 2011 Elsevier Ltd.

An T.K.,Pohang University of Science and Technology | Kang I.,Gyeongsang National University | Yun H.-J.,Gyeongsang National University | Cha H.,Pohang University of Science and Technology | And 8 more authors.
Advanced Materials | Year: 2013

A facile spin-coating method in which a small percentage of the solvent additive, 1-chloronaphthalene (CN), is found to increase the drying time during film deposition, is reported. The field-effect mobility of a PDPPDBTE film cast from a chloroform-CN mixed solution is 0.46 cm2 V-1 s -1. The addition of CN to the chloroform solution facilitates the formation of highly crystalline polymer structures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ary B.K.P.,Sepuluh Nopember Institute of Technology | Lee M.S.,Gyeongsang National University | Ahn S.W.,Gyeongsang National University | Lee D.H.,Inje University
International Communications in Heat and Mass Transfer | Year: 2012

The effect of a number of inclined perforated baffles on the flow patterns and heat transfer in the rectangular channel with different types of baffles is numerically and experimentally checked out. Reynolds numbers are varied between 23,000 and 57,000. The SST k-ω turbulence model is used in the method to predict turbulent flow. The baffles have the width of 19.8. cm, the square diamond type hole having one side length of 2.55. cm, and the inclination angle of 5°. The results show that the flow patterns around the holes are entirely different with different numbers of holes and it significantly affects the local heat transfer, and two baffles provide greater heat transfer performances than a single baffle. © 2012 Elsevier Ltd.

Cha J.,KAIST | Jin H.,University of British Columbia | Jung B.C.,Gyeongsang National University | Sung D.K.,KAIST
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2012

IEEE 802.11ac standard has newly adopted a downlink multi-user multiple-input and multiple-output (DL-MU-MIMO) scheme. For user multiplexing in downlink WLAN, we can also use a frame aggregation scheme for multiplexing multiple users' data with space-time block coding (STBC) for achieving spatial diversity. We compare the performance of the two downlink user multiplexing schemes: multi-user MIMO and frame aggregation in IEEE 802.11ac. If each user's encoded data stream has a similar length, the multi-user MIMO scheme yields better average throughput than the frame aggregation scheme. On the other hand, if each user's encoded data stream has a different length, the frame aggregation scheme outperforms the multi-user MIMO scheme in terms of average throughput. In a fast-varying channel, the multi-user MIMO scheme yields worse throughput due to the channel feedback overhead, compared to that with the frame aggregation scheme. We also observe that the multi-user frame aggregation scheme with STBC always outperforms a single-user transmission scheme with STBC in terms of average throughput due to enhanced MAC layer efficiency through frame aggregation. © 2012 IEEE.

Kim Y.J.,Pohang University of Science and Technology | Park K.H.,Gyeongsang National University | Ha J.-J.,Gyeongsang National University | Chung D.S.,Chung - Ang University | And 2 more authors.
Physical Chemistry Chemical Physics | Year: 2014

To evaluate the effect of side chain characteristics on the photovoltaic performance of small molecules containing both benzodithiophene (BDT) and thienopyrroledione (TPD), we designed and synthesized two such molecules, one containing a branched 2-ethylhexyl (2EH) side chain on the BDT unit (BDTEH-TTPD) and the other containing a linear n-octyl (C8) side chain on the BDT unit (BDTO-TTPD). The optical and electrochemical properties and crystalline structures of these molecules were examined. Compared to BDTO-TTPD, BDTEH-TTPD showed stronger light absorption, longer-range ordering and shorter π-π stacking distances between backbones. As a result, the power conversion efficiency of a bulk heterojunction solar cell based on BDTEH-TTPD (2.40%) was substantially higher than that of the BDTO-TTPD device (1.12%). © the Partner Organisations 2014.

Roldan A.,University of Jaén | Martinez-Moreno J.,University of Jaén | Roldan C.,University of Granada | Cho Y.J.,Gyeongsang National University
Fuzzy Sets and Systems | Year: 2014

In recent times, coupled, tripled and quadruple fixed point theorems have been intensively studied by many authors in the context of partially ordered complete metric spaces using different contractivity conditions. Roldán et al. showed a unified version of these results for nonlinear mappings in any number of variables (which were not necessarily permuted or ordered) introducing the notion of multidimensional coincidence point. Very recently, Choudhury et al. proved coupled coincidence point results in the context of fuzzy metric spaces in the sense of George and Veeramani. In this paper, using the idea of coincidence point for nonlinear mappings in any number of variables, we study a fuzzy contractivity condition to ensure the existence of coincidence points in the framework of fuzzy metric spaces provided with Hadžić type t-norms. Then, we present an illustrative example in which our methodology leads to the existence of coincidence points but previous theorems cannot be applied. © 2014 Elsevier B.V.

Ko J.-H.,Seoul National University | Mitina I.,Seoul National University | Tamada Y.,University of Wisconsin - Madison | Tamada Y.,Japan National Institute for Basic Biology | And 7 more authors.
EMBO Journal | Year: 2010

In Arabidopsis, the rapid-flowering summer-annual versus the vernalization-requiring winter-annual growth habit is determined by natural variation in FRIGIDA (FRI) and FLOWERING LOCUS C (FLC). However, the biochemical basis of how FRI confers a winter-annual habit remains elusive. Here, we show that FRI elevates FLC expression by enhancement of histone methyltransferase (HMT) activity. EARLY FLOWERING IN SHORT DAYS (EFS), which is essential for FRI function, is demonstrated to be a novel dual substrate (histone H3 lysine 4 (H3K4) and H3K36)-specific HMT. FRI is recruited into FLC chromatin through EFS and in turn enhances EFS activity and engages additional HMTs. At FLC, the HMT activity of EFS is balanced by the H3K4/H3K36- and H3K4-specific histone demethylase (HDM) activities of autonomous-pathway components, RELATIVE OF EARLY FLOWERING 6 and FLOWERING LOCUS D, respectively. Loss of HDM activity in summer annuals results in dominant HMT activity, leading to conversion to a winter-annual habit in the absence of FRI. Thus, our study provides a model of how growth habit is determined through the balance of the H3K4/H3K36-specific HMT and HDM activities. © 2010 European Molecular Biology Organization.

Hur D.-S.,Gyeongsang National University | Kim C.-H.,Korea University | Yoon J.-S.,Inje University
Coastal Engineering | Year: 2010

Most previous investigations related to composite breakwaters have focused on the wave forces acting on the structure itself from a hydrodynamic aspect. The foundational aspects of a composite breakwater under wave-induced cyclic loading are also important in studying the stability of a composite breakwater. In this study, numerical simulations were performed to investigate the wave-induced pore water pressure and flow changes inside the rubble mound of the composite breakwater and seabed foundation. The validity and applicability of the numerical model were demonstrated by comparing numerical results with existing experimental data. Moreover, the present model clearly has shown that the instantaneous directions of pore water flow motion inside the seabed induced by surface waves are in good agreement with the general wave-induced pore water flow inside the seabed. The model is further used to discuss the stability of a composite breakwater, i.e., the interaction among nonlinear waves, composite breakwater and seabed. Numerical results suggest that the stability of a composite breakwater is affected by not only downward shear flow generating on the seaward slope face of the rubble mound but, also, a high and dense pore water pressure gradient inside the rubble mound and seabed foundation. © 2010 Elsevier B.V.

Su D.,The Clean Tech Center | Ahn H.,Gyeongsang National University | Wang G.,The Clean Tech Center | Wang G.,Gyeongsang National University
Applied Physics Letters | Year: 2011

We have systematically investigated the diffusion mechanism of Li ions in Li2FeSiO4 and its delithiated product LiFeSiO4 based on the P21 symmetry using the first principle method. Calculations on the energy barriers for possible spatial hopping pathways predicted that the activation barriers along the [101] direction and Li ion layer in the ac plane are relatively low, which can ensure the facile lithium diffusion along those directions. The results indicate that Li 2FeSiO4 with the P21 symmetry is an ionic conductor for Li ions with two-dimensional diffusion. © 2011 American Institute of Physics.

Su D.,The Clean Tech Center | Ahn H.-J.,Gyeongsang National University | Wang G.,The Clean Tech Center | Wang G.,Gyeongsang National University
Journal of Power Sources | Year: 2013

One-dimensional magnetite (3O4) nanowires were synthesized by the low temperature hydrothermal method. The as-prepared 3O4 nanowires were systematically characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. X-ray diffraction and transmission electron microscopy have confirmed the cubic structure of 3O4 nanowires with a space group of Fd3m. Electrochemical properties of 3O4 nanowires were tested as anodes in lithium-ion cells by cyclic voltammetry and galvanostatic charge/discharge. 3O4 nanowires exhibited an excellent reversible lithium storage capacity and a satisfactory cycling performance. © 2012 Elsevier B.V. All rights reserved.

Lee S.-M.,Korea Electrotechnology Research Institute | Kim Y.-J.,Korea Electrotechnology Research Institute | Eom S.-W.,Korea Electrotechnology Research Institute | Choi N.-S.,Ulsan National Institute of Science and Technology | And 2 more authors.
Journal of Power Sources | Year: 2013

The self-discharge of Zn anode material is identified as a main factor that can limit the energy density of alkaline Zn-air batteries. Al2O 3 has most positive effect on controlling the hydrogen evolution reaction accompanied by corroding Zn anode among various additives. The overpotential for hydrogen evolution is measured by potentio-dynamic polarization analysis. Al-oxide with high overpotential for hydrogen evolution reaction is uniformly coated on the surface of Zn powders via chemical solution process. The morphology and composition of the surface-treated and pristine Zn powders are characterized by SEM, EDS, XRD and XPS analyses. Aluminum is distributed homogeneously over the surface of modified Zn powders, indicating uniform coating of Al-oxide, and O1s and Al2p spectra further identified surface coating layer to be the Al-oxide. The Al-oxide coating layer can prevent Zn from exposing to the KOH electrolyte, resulting in minimizing the side reactions within batteries. The 0.25 wt.% aluminum oxide coated Zn anode material provides discharging time of more than 10 h, while the pristine Zn anode delivers only 7 h at 25 mA cm-2. Consequently, a surface-treated Zn electrode can reduce self-discharge which is induced by side reaction such as H2 evolution, resulting in increasing discharge capacity. © 2012 Elsevier B.V. All rights reserved.

Yun H.-J.,Gyeongsang National University | Choi H.H.,Pohang University of Science and Technology | Kwon S.-K.,Gyeongsang National University | Kim Y.-H.,Gyeongsang National University | Cho K.,Pohang University of Science and Technology
Chemistry of Materials | Year: 2014

A new donor-acceptor organic semiconducting co-polymer (PDPP-TAT) containing acetylene linkages based on dithienyl-diketopyrrolopyrrole (tDPP) has been synthesized and compared with a tDPP-based co-polymer (PDPP-TVT) containing vinylene linkages. The sp-hybridized carbons in the acetylene linkages result in favorable overlap of the electron wave functions of the tDPP units along the main chain. Further, the π-conjugation of PDPP-TAT was found to be highly insensitive to the chain conformation, in contrast to that of PDPP-TVT. As a result, PDPP-TAT provides favorable charge transport for electrons as well as holes, and enables facile charge transport in amorphous and tie-molecular regions connecting its crystalline domains. PDPP-TAT exhibits ambipolar characteristics with a high electron/hole mobility ratio (μe/μh) of ∼0.3 in field-effect transistors, whereas PDPP-TVT exhibits unipolar characteristics with a μe/ μh value that is a factor of 30 lower. Our results demonstrate that the conformation sensitivity of charge transport is a vital factor in the electrical performances of actual organic transistor devices. © 2014 American Chemical Society.

Kim S.-O.,Gyeongsang National University | An T.K.,Pohang University of Science and Technology | Chen J.,Gyeongsang National University | Kang I.,Gyeongsang National University | And 5 more authors.
Advanced Functional Materials | Year: 2011

Four new quaterthiophene derivatives with end-groups composed of dicyclohexyl ethyl (DCE4T), dicyclohexyl butyl (DCB4T), cyclohexyl ethyl (CE4T), and cyclohexyl butyl (CB4T) were designed. All materials showed high solubility in common organic solvents. UV-vis absorption measurements showed that the quaterthiophene derivatives with asymmetrically substituted cyclohexyl end-groups (CE4T and CB4T) preferred H-type aggregation whereas those with symmetrically substituted cyclohexyl end-groups (DCE4T and DCB4T) preferred J-type aggregation. The molecular structure-dependent packing (H or J) of the new quaterthiophene derivatives was analyzed by grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. The field-effect mobilities of devices that incorporated the asymmetrical molecules, CE4T and CB4T, were quite high, above 10 - 2 cm 2 V - 1 s - 1 , due to H-aggregation, whereas the field-effect mobilities of devices that incorporated symmetrical molecules, DCE4T and DCB4T, were poor, below 10 - 4 cm 2 V - 1 s - 1 , due to J-aggregation. More importantly, H-aggregation within the thin film provided stable crystalline morphologies in the spin-coated films, and, thus, thin film transistors (TFTs) using cyclohexylated quaterthiophenes yielded highly reproducible transistor performances. The distributions of measured field-effect mobilities in transistors based on cyclohexylated quaterthiophenes with H-aggregation were remarkably narrow. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Choi S.H.,Gyeongsang National University | Jeong Y.-S.,Rutgers University | Jeong M.K.,Rutgers University | Jeong M.K.,KAIST
IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews | Year: 2010

Most recommendation algorithms attempt to alleviate information overload by identifying which items a user will find worthwhile. Content-based (CB) filtering uses the features of items, whereas collaborative filtering (CF) relies on the opinions of similar customers to recommend items. In addition to these techniques, hybrid methods have also been suggested to improve the performance of recommendation algorithms. However, even though recent hybrid methods have helped to avoid certain limitations of CB and CF, scalability and sparsity are still major problems in large-scale recommendation systems. In order to overcome these problems, this paper proposes a novel hybrid recommendation algorithm HYRED, which combines CF using the modified Pearsons binary correlation coefficients with CB filtering using the generalized distance-to-boundary-based rating. In the proposed recommendation system, the nearest and farthest neighbors of a target customer are utilized to yield a reduced dataset of useful information by avoiding scalability and sparsity problem when confronted by tremendous volumes of data. The use of reduced datasets enables us not only to lessen the computing effort, but also to improve the performance of recommendations. In addition, a generalized method to combine CF and CB system into a hybrid recommendation system is proposed by developing on the normalization metric. We have used this HYRED algorithm to experiment with all possible combination of CF and statistical-learning-based CB filtering. These experiments have shown that the use of reduced datasets saves computational time, and neighbor information improves performance. © 2010 IEEE.

Cheon Y.R.,Gyeongsang National University | Kim Y.J.,Pohang University of Science and Technology | Ha J.-J.,Gyeongsang National University | Kim M.-J.,Gyeongsang National University | And 2 more authors.
Macromolecules | Year: 2014

A-D-A conjugated polymer, PTPD-TVT, containing thienopyrroledione and thiophene-vinylene-thiophene (TVT) units was synthesized as an electron donor for organic photovoltaic devices. It possesses a small bandgap and has excellent coplanarity and high hole mobility. To further enhance the interchain interactions between the polymer chains, a selenophene-vinylene-selenophene (SVS) unit was also introduced and copolymerized to form the PTPD-SVS polymer. Devices made from PTPD-TVT and PTPD-SVS have rather promising power conversion efficiencies (PCEs) of 4.87 and 5.74%, respectively. The higher PCE value for solar cells based on PTPD-SVS was attributed to an enhanced carrier mobility resulting from stronger interchain aggregation in the BHJ active layer. These results show that the incorporation of a vinylene unit in TPD-based polymers is an effective way to reduce the bandgap and thereby improve charge transport for efficient photovoltaic devices. © 2014 American Chemical Society.

Kim Y.J.,Pohang University of Science and Technology | Baek J.Y.,Gyeongsang National University | Ha J.-J.,Gyeongsang National University | Chung D.S.,Chung - Ang University | And 3 more authors.
Journal of Materials Chemistry C | Year: 2014

A solution-processed alkylselenophene-substituted benzodithiophene (BDT) small molecule, namely, 3,3′-((4,8-bis(5-(2-ethylhexyl)selenophen-2-yl) benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(thiophene-5,2-diyl)) bis(5-octyl-1-(thiophen-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione) (BDTSe-TTPD), with broad absorption and suitable energy levels was synthesized. The widely used solvents o-dichlorobenzene (o-DCB), chlorobenzene (CB) or chloroform (CF) were used as the spin-coating solvent, to fabricate efficient photovoltaic devices with BDTSe-TTPD as the donor material and PC71BM as the acceptor. Devices made from a CF solution demonstrated better performance in terms of short-circuit current, fill factor and power conversion efficiency, as compared to the devices made from the o-DCB and CB solutions. Finally, by optimizing the thickness of the active layer, a power conversion efficiency of 4.37% was achieved on devices with an area of 0.09 cm2, under 100 mW cm-2 of simulated AM 1.5 irradiation. This journal is © the Partner Organisations 2014.

Jung J.H.,Gyeongsang National University | Lee J.H.,Gyeongsang National University | Shinkai S.,Sojo University | Shinkai S.,Japan Institute of Systems, Information Technologies and Nanotechnologies
Chemical Society Reviews | Year: 2011

Functionalized magnetic nanoparticles, composed of both inorganic and organic components, have recently been examined as promising platforms for detection and separation applications. This unique class of nanomaterials can retain not only beneficial features of both the inorganic and organic components, but can also provide the ability to systematically tune the properties of the hybrid materials through the combination of appropriate functional components. This tutorial review focuses on the recent development of functionalized magnetic nanoparticles for use in biological and environmental applications, in which these chromogenic and fluorogenic chemosensors can selectively detect and separate specific toxic metal ions. © 2011 The Royal Society of Chemistry.

Li K.,The Clean Tech Center | Wang B.,The Clean Tech Center | Su D.,The Clean Tech Center | Park J.,Gyeongsang National University | And 3 more authors.
Journal of Power Sources | Year: 2012

Sulfur/carbon nanocomposites have been successfully prepared by a solution-based processing technique using dimethyl sulfoxide as the solvent. The as-prepared nanocomposites were characterized by X-ray diffraction and field emission scanning electron microscopy. The electrochemical performance of sulfur/carbon nanocomposites were tested by cyclic voltammetry and galvanostatic charge/discharge cycling. When applied as the cathode material in lithium sulfur batteries, the as-prepared sulfur/carbon nanocomposites exhibited a high reversible capacity of 1220 mAh g -1 in the first cycle and maintained a satisfactory cyclability. This drastic improvement of specific capacity and cycling performance could be attributed to the reduced particle size of sulfur and the homogeneous distribution of sulfur nanoparticles on a carbon matrix, resulting from this novel solution-based processing technique. © 2011 Elsevier B.V. All rights reserved.

Back J.Y.,Gyeongsang National University | Yu H.,Pohang University of Science and Technology | Yu H.,Ulsan National Institute of Science and Technology | Song I.,Pohang University of Science and Technology | And 6 more authors.
Chemistry of Materials | Year: 2015

Systematic side-chain engineering has been performed for diketopyrrolopyrrole-selenophene vinylene selenophene (DPP-SVS) polymers to determine the optimal side-chain geometries for the most efficient charge transport, and the structure-property relationship has been thoroughly investigated using a range of analyses. A series of DPP-SVS polymers, ranging from 25-DPP-SVS to 32-DPP-SVS, with branched alkyl groups containing linear spacer groups from C2 to C9 has been synthesized, and the electrical performance of these polymers is significantly dependent on both the length of the spacer group and its odd-even characteristics. Spacer groups with even numbers of carbon atoms exhibit charge-carrier mobilities that are 1 order of magnitude higher than those with odd numbers of carbon atoms. The optimized charge transport has been obtained from 29-DPP-SVS with a C6 spacer, showing the maximum mobility of 13.9 cm2 V-1 s-1 (VGS, VDS = -100 V) and 17.8 cm2 V-1 s-1 (VGS, VDS = -150 V). Longer spacer groups deviate from the odd-even trend. In addition to the exceptionally high charge-carrier mobilities of the DPP-SVS polymers, the results obtained herein provide new insight into the molecular design of high-performance polymer semiconductors. © 2015 American Chemical Society.

Kim Y.,Daegu Gyeongbuk Institute of Science and Technology | Lim J.,Daegu Gyeongbuk Institute of Science and Technology | Lim J.,Pohang University of Science and Technology | Yeom M.,Daegu Gyeongbuk Institute of Science and Technology | And 10 more authors.
Cell Reports | Year: 2013

Many organisms, including plants, use the circadian clock to measure the duration of day and night. Daily rhythms in the plant circadian system are generated by multiple interlocked transcriptional/translational loops and also by spatial regulations such as nuclear translocation. GIGANTEA (GI), one of the key clock components in Arabidopsis, makes distinctive nuclear bodies like other nuclear-localized circadian regulators. However, little is known about the dynamics or roles of GI subnuclear localization. Here, we characterize GI subnuclear compartmentalization and identify unexpected dynamic changes under diurnal conditions. We further identify EARLY FLOWERING 4 (ELF4) as a regulator of GI nuclear distribution through a physical interaction. ELF4 sequesters GI from the nucleoplasm, where GI binds the promoter of CONSTANS (. CO), to discrete nuclear bodies. We suggest that the subnuclear compartmentalization of GI by ELF4 contributes to the regulation of photoperiodic flowering.

Kang I.,Gyeongsang National University | An T.K.,Pohang University of Science and Technology | Hong J.-A.,Gyeongsang National University | Yun H.-J.,Gyeongsang National University | And 5 more authors.
Advanced Materials | Year: 2013

A new polymeric semiconductor, PDPPDTSE, is reported which is composed of a diketopyrrolopyrrole moiety and selenophenylene vinylene selenophene, with a high field-effect mobility achieved through intermolecular donor-acceptor interactions. The field-effect mobility of OFET devices based on PDPPDTSE by spin-casting is 4.97 cm2 V-1 s-1, which is higher than predecessor polymeric semiconductors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Su D.,The Clean Tech Center | Wang C.,Yangzhou University | Ahn H.,Gyeongsang National University | Wang G.,The Clean Tech Center
Physical Chemistry Chemical Physics | Year: 2013

Single crystalline SnO2 nanocrystals (∼60 nm in size) with a uniform octahedral shape were synthesised using a hydrothermal method. Their phase and morphology were characterized by XRD and FESEM observation. TEM and HRTEM analyses identified that SnO2 octahedral nanocrystals grow along the [001] direction, consisting of dominantly exposed {221} high energy facets. When applied as anode materials for Na-ion batteries, SnO2 nanocrystals exhibited high reversible sodium storage capacity and excellent cyclability (432 mA h g-1 after 100 cycles). In particular, SnO 2 nanocrystals also demonstrated a good high rate performance. Ex situ TEM analysis revealed the reaction mechanism of SnO2 nanocrystals for reversible Na ion storage. It was found that Na ions first insert into SnO2 crystals at the high voltage plateau (from 3 V to ∼0.8 V), and that the exposed (1 × 1) tunnel-structure could facilitate the initial insertion of Na ions. Subsequently, Na ions react with SnO2 to form NaxSn alloys and Na2O in the low voltage range (from ∼0.8 V to 0.01 V). The superior cyclability of SnO 2 nanocrystals could be mainly ascribed to the reversible Na-Sn alloying and de-alloying reactions. Furthermore, the reduced Na2O "matrix" may help retard the aggregation of tin nanocrystals, leading to an enhanced electrochemical performance. This journal is © the Owner Societies 2013.

Feng F.,Shaanxi Normal University | Feng F.,Xi'an Institute of Post and Telecommunications | Liu X.,Xi'an Institute of Post and Telecommunications | Leoreanu-Fotea V.,Al. I. Cuza University | Jun Y.B.,Gyeongsang National University
Information Sciences | Year: 2011

In this study, we establish an interesting connection between two mathematical approaches to vagueness: rough sets and soft sets. Soft set theory is utilized, for the first time, to generalize Pawlak's rough set model. Based on the novel granulation structures called soft approximation spaces, soft rough approximations and soft rough sets are introduced. Basic properties of soft rough approximations are presented and supported by some illustrative examples. We also define new types of soft sets such as full soft sets, intersection complete soft sets and partition soft sets. The notion of soft rough equal relations is proposed and related properties are examined. We also show that Pawlak's rough set model can be viewed as a special case of the soft rough sets, and these two notions will coincide provided that the underlying soft set in the soft approximation space is a partition soft set. Moreover, an example containing a comparative analysis between rough sets and soft rough sets is given. © 2010 Elsevier Inc. All rights reserved.

Jin H.,KAIST | Jung B.C.,Gyeongsang National University | Sung D.K.,KAIST
IEEE Transactions on Wireless Communications | Year: 2011

Due to high spectral-efficiency of multiple-input multiple-output (MIMO) transmission techniques, IEEE 802.11n WLAN system adopted a single-user MIMO (SU-MIMO) scheme in which multiple symbol streams are transmitted from a single station (STA) to enhance the system performance. On the other hand, recently, adoption of a multi-user MIMO (MU-MIMO) scheme for multi-packet reception (MPR) in uplink WLAN has also attracted attention. The SU-MIMO scheme achieves a MIMO multiplexing gain at physical (PHY) layer while the MU-MIMO scheme achieves a MIMO multiplexing gain at medium access control (MAC) layer. Thus, there is a fundamental question which scheme is a better solution for uplink WLANs and, in this paper, we analyze and compare these two schemes with random STA distribution scenarios. Moreover, with the adaptation of MAC layer parameters, we also analyze and compare the maximum throughput performance of both the SU-and MU-MIMO schemes in uplink WLANs and we find a proper decision criterion to select the MIMO mode in uplink WLANs. © 2011 IEEE.

Wang L.,University of South China | Je Cho Y.,Gyeongsang National University | Huang N.-J.,University of Sichuan
Fuzzy Sets and Systems | Year: 2011

In this paper, we study the economic model proposed by Anderlini and Canning, a parameterized class of generalized abstract fuzzy economies together with an associated abstract rationality function, and show that the structural stability of this model implies its robustness to ε-equilibria. © 2011 Elsevier B.V.

Cho Y.J.,Gyeongsang National University | Saadati R.,Islamic Azad University at Tehran | Wang S.,North China Electrical Power University | Wang S.,Gyeongsang National University
Computers and Mathematics with Applications | Year: 2011

In this paper, we introduce a concept of the c-distance in a cone metric space and, by using the concept of the c-distance, prove some fixed point theorems in ordered cone metric spaces. © 2010 Elsevier Ltd. All rights reserved.

Kim G.C.,Pusan National University | Lee H.W.,Pohang University of Science and Technology | Byun J.H.,Gyeongsang National University | Chung J.,Pusan National University | And 2 more authors.
Plasma Processes and Polymers | Year: 2013

Oral cavity and teeth are important organs of human body. The attention and cost for dental treatments increase every year. In dental clinics, the most common diseases are dental caries, periodontal disease, and stomatitis. Dental aesthetics such as tooth whitening is one of important part of dental clinics. However, conventional treatment methods in dental clinics have limitations by pain and long-time treatment. Nonthermal plasmas have shown great potential as noble techniques to dental applications due to safety and multi-functional effects achieved by the abundant plasma components including charged particles, radiation, and reactive species. Reactive oxygen species generated from plasmas can effectively inhibit pathogen activity. The use of nonthermal plasmas is efficient in treating oral diseases because the construction of the plasma devices allows easy access to the oral cavity. However, few studies have been conducted on the use of plasmas in oral disease. Tooth aesthetics, as well as treatment of oral diseases, are important in determining the quality of human life. Recent studies have shown nonthermal plasmas to have strong tooth-bleaching effects. Studies on oral care using nonthermal plasmas will significantly contribute to oral health in the future. Dental applications of nonthermal atmospheric pressure plasmas (NAPP) are reviewed in this paper. Oral diseases are caused by anaerobic or oxygen-sensitive pathogenic microorganisms. NAPP are efficient in treating oral diseases due to their components, mainly reactive oxygen species; moreover NAPP have been recently shown to have strong tooth-bleaching effects. Continuing research on oral care using NAPP will contribute to improving oral health in the future. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Su D.,The Clean Tech Center | Wang C.,Yangzhou University | Ahn H.-J.,Gyeongsang National University | Wang G.,The Clean Tech Center
Chemistry - A European Journal | Year: 2013

Single crystalline rhombus-shaped Na0.7MnO2 nanoplates have been synthesized by a hydrothermal method. TEM and HRTEM analyses revealed that the Na0.7MnO2 single crystals predominantly exposed their (100) crystal plane, which is active for Na +-ion insertion and extraction. When applied as cathode materials for sodium-ion batteries, Na0.7MnO2 nanoplates exhibited a high reversible capacity of 163 mA h g-1, a satisfactory cyclability, and a high rate performance. The enhanced electrochemical performance could be ascribed to the predominantly exposed active (100) facet, which could facilitate fast Na+-ion insertion/extraction during the discharge and charge process. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Park H.J.,Inje University | Lee D.H.,Inje University | Ahn S.W.,Gyeongsang National University
International Journal of Thermal Sciences | Year: 2013

Local Nusselt numbers in a spirally fluted circular tube are presented. Thermochromic liquid crystals and shroud-transient technique are used to measure spatially-resolved surface temperature distributions, which are used to deduce local Nusselt numbers. The Reynolds number Re ranges from 30,000 to 70,000, a spiral angle θ is fixed at 60° and the dimensionless streamwise distance z/d ranges from 0 to 4.5. The results show that in general, the local Nusselt numbers monotonically decrease with a distance away from both windward and leeward crests of the spiral flute and reach a minimum value near its valley for all Re's and z/d's tested. The local Nusselt numbers in the spirally fluted tube are maximum 179-89.3% higher for Re = 30,000-70,000 near the windward crest at z/d = 4.5 than the fully developed values in the smooth tube. It is also found that the average Nusselt numbers are 52-23.7% higher for Re = 30,000-70,000 than the fully developed values in the smooth tube. © 2012 Elsevier Masson SAS. All rights reserved.

Wook Lee Y.,KAIST | Wook Lee Y.,Gyeongsang National University | Kim M.,KAIST | Kim M.,Gyeongsang National University | And 2 more authors.
Chemical Communications | Year: 2010

Cubic, multi-armed, and dendritic Pd nanoparticles with efficient electrocatalytic activities toward formic acid oxidation can be selectively prepared with high yields and good uniformity by just changing the injection sequence of reductant and surfactant. © The Royal Society of Chemistry 2010.

Hwang M.C.,Gyeongsang National University | Jang J.-W.,Gyeongsang National University | An T.K.,Pohang University of Science and Technology | Park C.E.,Pohang University of Science and Technology | And 2 more authors.
Macromolecules | Year: 2012

A series of new p-type polymers, PNDT-T and PNDT-TT, with enforced coplanar structure for effective χ-electron delocalization, having naphtho[2,1-b:3,4-b′]dithiophene and thiophenes as main core units, were successfully synthesized by Stille coupling reaction. The naphtho[2,1-b:3,4- b′]dithiophene unit of the polymer main chain enhances charge carrier mobility by extending χ-conjugation length and rigidly enforced coplanar structure. Both polymers, PNDT-T and PNDT-TT, have high thermal stability up to 250 °C with a high T g of 402 °C. On the basis of AFM and XRD results, it was found that PNDT-TT showed relatively more highly ordered intermolecular structures than did PNDT-T, with thiophene unit and high field-effect mobility, because the bithiophene unit provides crystallinity with increasing planarity and enough space for interdigitation of the long alkyl side chains for high order. These new p-type polymers PNDT-T and PNDT-TT exhibit high carrier mobilities of 0.01 and 0.076 cm 2/(V s) and on/off ratios of 4 × 10 5 and 7 × 10 6, respectively. The above results indicate that the plate structure with a sulfur-containing fully aromatic system, which has the upper direction extended, could enhance the thermal stability and charge transport characteristics for OTFT applications. © 2012 American Chemical Society.

Sintunavarat W.,King Mongkut's University of Technology Thonburi | Cho Y.J.,Gyeongsang National University | Kumam P.,King Mongkut's University of Technology Thonburi
Computers and Mathematics with Applications | Year: 2011

Recently, Cho et al. [Y.J. Cho, R. Saadati, S.H. Wang, Common fixed point theorems on generalized distance in ordered cone metric spaces, Comput. Math. Appl. 61 (2011) 12541260] introduced the concept of the c-distance in a cone metric space and established some fixed point theorems on c-distance. The aim of this paper is to extend and generalize the main results of Cho et al. [20] and also show some examples to validate our main results. © 2011 Elsevier Ltd. All rights reserved.

Cha H.,Pohang University of Science and Technology | Chung D.S.,Dong - A University | Bae S.Y.,Korea University | Lee M.-J.,Gyeongsang National University | And 6 more authors.
Advanced Functional Materials | Year: 2013

Two anthracene-based star-shaped conjugated small molecules, 5',5a″-(9,10-bis((4-hexylphenyl)ethynyl)anthracene-2,6-diyl)bis(5-hexyl-2, 2'-bithiophene), HBantHBT, and 5',5a″-(9,10-bis(phenylethynyl)anthracene- 2,6-diyl)bis(5-hexyl-2,2'-bithiophene), BantHBT, are used as electron-cascade donor materials by incorporating them into organic photovoltaic cells prepared using a poly((5,5-E-alpha-((2-thienyl)methylene)-2-thiopheneacetonitrile)-alt-2, 6-[(1,5-didecyloxy)naphthalene])) (PBTADN):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) blend. The small molecules penetrate the PBTADN:PC71BM blend layer to yield complementary absorption spectra through appropriate energy level alignment and optimal domain sizes for charge carrier transfer. A high short-circuit current (JSC) and fill factor (FF) are obtained using solar cells prepared with the ternary blend. The highest photovoltaic performance of the PBTADN:BantHBT:PC71BM blend solar cells is characterized by a JSC of 11.0 mA cm-2, an open circuit voltage (VOC) of 0.91 V, a FF of 56.4%, and a power conversion efficiency (PCE) of 5.6% under AM1.5G illumination (with a high intensity of 100 mW-2). The effects of the small molecules on the ternary blend are investigated by comparison with the traditional poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) system. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Park J.W.,Gyeongsang National University | Lee D.H.,Pohang University of Science and Technology | Chung D.S.,Pohang University of Science and Technology | Kang D.-M.,Gyeongsang National University | And 3 more authors.
Macromolecules | Year: 2010

We report the synthesis of polythiophene derivatives that contain decylthiophenyl side chains, using synthetic strategies that achieve high organic semiconductor field effect mobilities by enhancing the π-conjugation in the side-chain conjugated system. With increased charge densities, we obtained high field effect mobilities, up to 0.050 and 0.003 cm2 /(V s) from poly(3,4″-di(decylthiophenyl) sexithiophene) (PDTST) and poly(3,4″-di(decylthiophenyl) quaterthiophene) (PDTQT), respectively. PDTQT and PDTST are characterized by UV-vis, DSC, AFM images, and GIXD patterns. Increased conformational rotation in the main backbone, caused by intramolecular repulsion between neighboring thiophene units, lowers the HOMO level and introduces remarkable chemical stability in the presence of air as well as increases processability due to high solubility. The high solubility and oxidative stability of PDTST and PDTQT indicate that these side-chain conjugation system strategies have the potential for improving other thiophene-based semiconducting polymers. © 2010 American Chemical Society.

Xu Z.-Y.,Pohang University of Science and Technology | Lee K.H.,Pohang University of Science and Technology | Dong T.,Pohang University of Science and Technology | Jeong J.C.,Gyeongsang National University | And 9 more authors.
Plant Cell | Year: 2012

The phytohormone abscisic acid (ABA) plays a critical role in various physiological processes, including adaptation to abiotic stresses. In Arabidopsis thaliana, ABA levels are increased both through de novo biosynthesis and via β-glucosidase homolog1 (BG1)-mediated hydrolysis of Glc-conjugated ABA (ABA-GE). However, it is not known how many different b-glucosidase proteins produce ABA from ABA-GE and how the multiple ABA production pathways are coordinated to increase ABA levels. Here, we report that a previously undiscovered β-glucosidase homolog, BG2, produced ABA by hydrolyzing ABA-GE and plays a role in osmotic stress response. BG2 localized to the vacuole as a high molecular weight complex and accumulated to high levels under dehydration stress. BG2 hydrolyzed ABA-GE to ABA in vitro. In addition, BG2 increased ABA levels in protoplasts upon application of exogenous ABA-GE. Overexpression of BG2 rescued the bg1 mutant phenotype, as observed for the overexpression of NCED3 in bg1 mutants. Multiple Arabidopsis bg2 alleles with a T-DNA insertion in BG2 were more sensitive to dehydration and NaCl stress, whereas BG2 overexpression resulted in enhanced resistance to dehydration and NaCl stress. Based on these observations, we propose that, in addition to the de novo biosynthesis, ABA is produced in multiple organelles by organelle-specific β-glucosidases in response to abiotic stresses. © 2012 American Society of Plant Biologists. All rights reserved.

Cha H.,Pohang University of Science and Technology | Park J.W.,Gyeongsang National University | Chung D.S.,Dong - A University | An T.K.,Pohang University of Science and Technology | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

A conjugated polymer donor material, poly(3,4′′′- di(decylthiophenyl)quaterthiophene) (PDTQT), featuring decylthiophenyl side chains on the polymer backbone, was introduced to reduce the crystallinity of poly(quaterthiophene) (PQT-C12) layers in organic photovoltaic cells. The resulting PDTQT:PC 71BM blend active layer formed a well-interpenetrated nanoscale morphology that increased the power conversion efficiency (PCE) relative to devices based on highly crystalline PQT-C12. Bulk heterojunction solar cells fabricated using the PDTQT:PC 71BM blend thin films yielded the best photovoltaic performances with a high short-circuit current density of 9.8 mA cm -2, a high open-circuit voltage of 0.91 V, a fill factor of 0.36, and a high PCE of 3.2% under AM 1.5G illumination with an intensity of 100 mW cm -2. Decylthiophenyl side chain substitution appeared to be an effective strategy for obtaining high organic photovoltaic cell device performances. This journal is © The Royal Society of Chemistry 2012.

Lee Y.W.,KAIST | Lee Y.W.,Gyeongsang National University | Kim M.,KAIST | Kim M.,Gyeongsang National University | And 4 more authors.
Journal of Physical Chemistry C | Year: 2010

Dendritic Au-Pd alloy nanoparticles were synthesized in high yield through the coreduction of HAuCl4 and K2PdCl4 in aqueous solutions by using hydrazine as a reducing agent. Relative compositions between Au and Pd at the particle surfaces as well as in bulk phases could be modulated by controlling the molar ratios between metal precursors in the feeding solutions. The formation of nanodendrites may be the result of the fast reduction rate of metal ions and subsequent fast, kinetically controlled growth of particles. The prepared alloy nanoparticles exhibit efficient electrocatalytic activities and stabilities toward ethanol oxidation in alkaline media. The enhanced electrocatalytic properties of dendritic particles can be attributed to the presence of a large number of active sites on their surfaces. © 2010 American Chemical Society.

Khan M.S.,Gyeongsang National University | Khan M.S.,Panjab University | Halagowder D.,University of Madras | Devaraj S.N.,Gyeongsang National University
Food and Chemical Toxicology | Year: 2011

The modifying effect of chemically modified chrysin on formation of preneoplastic foci induced by N-nitrosodiethylamine (DEN) was investigated in male rats. Male Wistar rats were administered three intraperitoneal injections of DEN (200. mg/kg bodyweight) interspersed by 2. weeks with or without an oral dose of dimethoxy flavone (DMF 100. mg/kg bodyweight), 2. weeks after DEN initiation. The number of GST-Pi positive foci and proliferating cell nuclear antigen (PCNA)-positive cells were significantly suppressed by the administration of DMF. Real-time RT-PCR analysis revealed that DMF treatment increased mRNA expression levels of apoptotic proteins p53 and fas, cell cycle regulatory proteins chek 2, cdkn1a, rad 50, anti-inflammatory protein pparg whereas the mRNA expression levels of b. cl-2 and p. rdx-2 were decreased compared to mRNA levels in DEN-treated group. Therefore, we propose that DMF partially suppresses the formation of preneoplastic lesions in rats following DEN exposure by regulating anti-inflammatory and apoptosis-promoting events and restoring the cellular redox balance altered by DEN. © 2010 Elsevier Ltd.

Efroni I.,Weizmann Institute of Science | Efroni I.,New York University | Han S.-K.,University of Pennsylvania | Kim H.J.,Gyeongsang National University | And 7 more authors.
Developmental Cell | Year: 2013

Plant shoots display indeterminate growth, while their evolutionary decedents, the leaves, are determinate. Determinate leaf growth is conditioned by the CIN-TCP transcription factors, which promote leaf maturation and are negatively regulated by miR319 in leaf primordia. Here we show that CIN-TCPs reduce leaf sensitivity to cytokinin (CK), a phytohormone implicated in inhibition of differentiation in the shoot. We identify the SWI/SNF chromatin remodeling ATPase BRAHMA (BRM) as a genetic mediator of CIN-TCP activities and CK responses. An interactome screen further revealed that SWI/SNF complex components including BRM preferentially interacted with basic-helix-loop-helix (bHLH) transcription factors and the bHLH-related CIN-TCPs. Indeed, TCP4 and BRM interacted in planta. Both TCP4 and BRM bound the promoter of an inhibitor of CK responses, ARR16, and induced its expression. Reconstituting ARR16 levels in leaves with reduced CIN-TCP activity restored normal growth. Thus, CIN-TCP and BRM together promote determinate leaf growth by stage-specific modification of CK responses. © 2013 Elsevier Inc.

Su D.,The Clean Tech Center | Ahn H.-J.,Gyeongsang National University | Wang G.,The Clean Tech Center
NPG Asia Materials | Year: 2013

Sodium-ion batteries are being considered as a promising system for stationary energy storage and conversion, owing to the natural abundance of sodium. It is important to develop new cathode and anode materials with high capacities for sodium-ion batteries. Herein, we report the synthesis of β-MnO2 nanorods with exposed tunnel structures by a hydrothermal method. The as-prepared β-MnO2 nanorods have exposed {111} crystal planes with a high density of (1 × 1) tunnels, which leads to facile sodium ion (Na-ion) insertion and extraction. When applied as cathode materials in sodium-ion batteries, β-MnO2 nanorods exhibited good electrochemical performance with a high initial Na-ion storage capacity of 350 mAh g-1. β-MnO2 nanorods also demonstrated a satisfactory high-rate capability as cathode materials for sodium-ion batteries.

Lee K.Y.,Gyeongsang National University | Lee Y.W.,KAIST | Lee Y.W.,Korea Basic Science Institute | Kim M.,Korea University | Kim T.H.,Gyeongsang National University
Journal of Materials Chemistry A | Year: 2014

We demonstrate the fabrication of Bi21Pt35Pd 44 alloy porous nanoplates by a galvanic replacement method using Bi65Pt35 bimetallic nanoplates as the sacrificial template. Bi65Pt35 nanoplates, prepared by reduction with diol (1,2-hexadecanediol) at low temperature (100 °C), were converted to the porous nanoplate structure by a K2PdCl4/water/ethanol (1/1, v/v) mixed solution via galvanic replacement between bismuth and palladium. The formation of Bi21Pt35Pd44 porous nanoplates is attributed to disperse crystallization under conditions of high nucleation rate. The electro-chemically active surface area (ECSA) for the Bi21Pt35Pd44 alloy porous nanoplate is measured to be 0.943 cm2. This value is 3 times greater than the ECSA (0.283 cm2) of the commercial Pt/C (Alpha, Pt 20%) electrode. The electro-catalytic activity of the prepared porous nanoplates was examined for the oxidation of methanol in acidic solution. The Bi21Pt 35Pd44 porous nanoplates can effectively catalyze oxidation of methanol in acidic solution, probably owing to their larger surface area and many active reaction sites. The Bi21Pt35Pd 44 porous nanoplates provide a new form of unsupported catalysts in contrast to the traditional supported nanoparticle catalyst and can be uniformly synthesized and separated easily from the reaction mixtures without aggregation. © 2014 The Royal Society of Chemistry.

Jun Y.B.,Gyeongsang National University | Lee K.J.,Hannam University | Park C.H.,University of Ulsan
Computers and Mathematics with Applications | Year: 2010

In the paper [P.K. Maji, R. Biswas, A.R. Roy, Fuzzy soft sets, J. Fuzzy Math. 9 (3) (2001) 589-602], Maji et al. introduced the concept of fuzzy soft sets as a generalization of the standard soft sets, and presented an application of fuzzy soft sets in a decision making problem. The aim of this manuscript is to apply fuzzy soft set for dealing with several kinds of theories in BCK/BCI-algebras. The notions of fuzzy soft BCK/BCI-algebras, (closed) fuzzy soft ideals and fuzzy soft p-ideals are introduced, and related properties are investigated. © 2010 Elsevier Ltd. All rights reserved.

Kang G.,Gyeongsang National University | Son H.,Gyeongsang National University | Lim J.M.,Ewha Womans University | Kweon H.-S.,Korea Basic Science Institute | And 3 more authors.
Chemistry - A European Journal | Year: 2012

The zinc tank: A new fluoro-chromogenic chemosensor based on BODIPY-functionalized Fe 3O 4 nanoparticles (1) has been prepared. Chemoprobe 1 exhibits high selectivity for Zn 2+ over other competing metal ions tested. Moreover, confocal microscopy experiments established that 1 can be used for detecting Zn 2+ levels in living cells (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jung J.H.,Gyeongsang National University | Park M.,Gyeongsang National University | Shinkai S.,Sojo University | Shinkai S.,Japan Institute of Systems, Information Technologies and Nanotechnologies
Chemical Society Reviews | Year: 2010

This critical review focuses on the preparation methods of a variety of the silica nanotubes by self-assembled organogels and the recent development of silica-based organic-inorganic hybrid nanomaterials for use as chemosensors in environmental studies as well as adsorbents for inorganic guest molecules and in biological applications for delivery of organic guest molecules (127 references). © 2010 The Royal Society of Chemistry.

Su D.,The Clean Tech Center | Ahn H.-J.,Gyeongsang National University | Wang G.,The Clean Tech Center
Chemical Communications | Year: 2013

An in situ hydrothermal synthesis approach has been developed to prepare SnO2@graphene nanocomposites. The nanocomposites exhibited a high reversible sodium storage capacity of above 700 mA h g-1 and excellent cyclability for Na-ion batteries. In particular, they also demonstrated a good high rate capability for reversible sodium storage. © 2013 The Royal Society of Chemistry.

Sun B.,The Clean Tech Center | Liu H.,The Clean Tech Center | Munroe P.,University of New South Wales | Ahn H.,Gyeongsang National University | Wang G.,The Clean Tech Center
Nano Research | Year: 2012

A nanocomposite of CoO and a mesoporous carbon (CMK-3) has been studied as a cathode catalyst for lithium-oxygen batteries in alkyl carbonate electrolytes. The morphology and structure of the as-prepared nanocomposite were characterized by field emission scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy. The electrochemical properties of the mesoporous CoO/CMK-3 nanocomposite as a cathode catalyst in lithium-oxygen batteries were studied using galvanostatic charge-discharge methods. The reaction products on the cathode were analyzed by Fourier transform infrared spectroscopy. The CoO/CMK-3 nanocomposite exhibited better capacity retention than bare mesoporous CMK-3 carbon, Super-P carbon or CoO/Super-P nanocomposite. The synergistic effects arising from the combination of CoO nanoparticles and the mesoporous carbon nanoarchitecture may be responsible for the optimum catalytic performance in lithium-oxygen batteries. © 2012 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

Yun H.-J.,Gyeongsang National University | Choi H.H.,Pohang University of Science and Technology | Kwon S.-K.,Gyeongsang National University | Kim Y.-H.,Gyeongsang National University | Cho K.,Pohang University of Science and Technology
ACS Applied Materials and Interfaces | Year: 2015

The fine tuning of the dominant polarity in polymer semiconductors is a key issue for high-performance organic complementary circuits. In this paper, we demonstrate a new methodology for addressing this issue in terms of molecular design. In an alternating conjugated donor-acceptor copolymer system, we systematically engineered the chemical linkages that connect the aromatic units in donor moieties. Three donor moieties, thiophene-vinylene-thiophene (TVT), thiophene-acetylene-thiophene (TAT), and thiophene-cyanovinylene-thiophene (TCNT), were combined with an acceptor moiety, thienoisoindigo (TIID), and finally, three novel TIID-based copolymers were synthesized: PTIID-TVT, PTIID-TAT, and PTIID-TCNT. We found that the vinylene, acetylene, and cyanovinylene linkages decisively affect the energy structure, molecular orbital delocalization, microstructure, and, most importantly, the dominant polarity of the polymers. The vinylene-linked PTIID-TVT field-effect transistors (FETs) exhibited intrinsic hole and electron mobilities of 0.12 and 1.5 × 10-3 cm2 V-1 s-1, respectively. By contrast, the acetylene-linked PTIID-TAT FETs exhibited significantly improved intrinsic hole and electron mobilities of 0.38 and 0.03 cm2 V-1 s-1, respectively. Interestingly, cyanovinylene-linked PTIID-TCNT FETs exhibited reverse polarity, with hole and electron mobilities of 0.07 and 0.19 cm2 V-1 s-1. As a result, the polarity balance, which is quantified as the electron/hole mobility ratio, was dramatically tuned from 0.01 to 2.7. Our finding demonstrates a new methodology for the molecular design of high-performance organic complementary circuits. (Graph Presented). © 2015 American Chemical Society.

Kim J.I.,Purdue University | Murphy A.S.,Purdue University | Baek D.,Gyeongsang National University | Lee S.-W.,Gyeongnam National University of Science and Technology | And 4 more authors.
Journal of Experimental Botany | Year: 2011

The Arabidopsis thaliana YUCCA family of flavin monooxygenase proteins catalyses a rate-limiting step in de novo auxin biosynthesis. A YUCCA6 activation mutant, yuc6-1D, has been shown to contain an elevated free IAA level and to display typical high-auxin phenotypes. It is reported here that Arabidopsis plants over-expressing YUCCA6, such as the yuc6-1D activation mutant and 35S:YUC6 transgenic plants, displayed dramatic longevity. In addition, plants over-expressing YUCCA6 exhibited classical, delayed dark-induced and hormone-induced senescence in assays using detached rosette leaves. However, plants over-expressing an allele of YUCCA6, that carries mutations in the NADPH cofactor binding site, exhibited neither delayed leaf senescence phenotypes nor phenotypes typical of auxin overproduction. When the level of free IAA was reduced in yuc6-1D by conjugation to lysine, yuc6-1D leaves senesced at a rate similar to the wild-type leaves. Dark-induced senescence in detached leaves was accompanied by a decrease in their free IAA content, by the reduced expression of auxin biosynthesis enzymes such as YUCCA1 and YUCCA6 that increase cellular free IAA levels, and by the increased expression of auxin-conjugating enzymes encoded by the GH3 genes that reduce the cellular free auxin levels. Reduced transcript abundances of SAG12, NAC1, and NAC6 during senescence in yuc6-1D compared with the wild type suggested that auxin delays senescence by directly or indirectly regulating the expression of senescence-associated genes. © 2011 The Author(s).

Lei M.,Tsinghua University | Zhu C.,Tsinghua University | Liu Y.,Tsinghua University | Karthikeyan A.S.,Purdue University | And 5 more authors.
New Phytologist | Year: 2011

With the exception of root hair development, the role of the phytohormone ethylene is not clear in other aspects of plant responses to inorganic phosphate (Pi) starvation. The induction of AtPT2 was used as a marker to find novel signalling components involved in plant responses to Pi starvation. Using genetic and chemical approaches, we examined the role of ethylene in the regulation of plant responses to Pi starvation. hps2, an Arabidopsis mutant with enhanced sensitivity to Pi starvation, was identified and found to be a new allele of CTR1 that is a key negative regulator of ethylene responses. 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, increases plant sensitivity to Pi starvation, whereas the ethylene perception inhibitor Ag+ suppresses this response. The Pi starvation-induced gene expression and acid phosphatase activity are also enhanced in the hps2 mutant, but suppressed in the ethylene-insensitive mutant ein2-5. By contrast, we found that ethylene signalling plays a negative role in Pi starvation-induced anthocyanin production. These findings extend the roles of ethylene in the regulation of plant responses to Pi starvation and will help us to gain a better understanding of the molecular mechanism underlying these responses. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

Su D.,University of Technology, Sydney | Ahn H.-J.,Gyeongsang National University | Wang G.,University of Technology, Sydney | Wang G.,Gyeongsang National University
Journal of Materials Chemistry A | Year: 2013

Two types of MnO2 polymorphs, α-MnO2 and β-MnO2 nanorods, have been synthesized by a hydrothermal method. Their crystallographic phases, morphologies, and crystal structures were characterized by XRD, FESEM and TEM analysis. Different exposed crystal planes have been identified by TEM. The electrochemical properties of α-MnO 2 and β-MnO2 nanorods as cathode materials in Na-ion batteries were evaluated by galvanostatic charge/discharge testing. Both α-MnO2 and β-MnO2 nanorods achieved high initial sodium ion storage capacities of 278 mA h g-1 and 298 mA h g-1, respectively. β-MnO2 nanorods exhibited a better electrochemical performance such as good rate capability and cyclability than that of α-MnO2 nanorods, which could be ascribed to a more compact tunnel structure of β-MnO2 nanorods. Furthermore, the one-dimensional architecture of nanorods could also contribute to facile sodium ion diffusion in the charge and discharge process. © The Royal Society of Chemistry 2013.

Ryu H.S.,Gyeongsang National University | Park J.W.,Gyeongsang National University | Park J.,Gyeongsang National University | Ahn J.-P.,Korea Institute of Science and Technology | And 6 more authors.
Journal of Materials Chemistry A | Year: 2013

To enhance the stability of sulfur cathode for a high energy lithium-sulfur battery, sulfur-activated carbon (S-AC) composite was prepared by encapsulating sulfur into micropores of activated carbon using a solution-based processing technique. In the analysis using the prepared specimen of S-AC composite by the focused ion beam (FIB) technique, the elemental sulfur exists in a highly dispersed state inside the micropores of activated carbon, which has a large surface area and a narrow pore distribution. The S-AC composite was characterized through X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) method, selected area electron diffraction (SAED), energy dispersive X-ray spectrometry (EDX), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA), and field emission scanning electron microscopy (FESEM). A lithium-sulfur cell using the S-AC composite has a high first discharge capacity over 800 mA h g -1 S even at a high current density such as 2C (3200 mA g -1 S) and has good cycleability around 500 mA h g-1 S discharge capacity at the 50th cycle at the same current density. © 2013 The Royal Society of Chemistry.

Liu H.,University of Queensland | Wang G.,University of Technology, Sydney | Liu J.,University of Queensland | Qiao S.,University of Queensland | Ahn H.,Gyeongsang National University
Journal of Materials Chemistry | Year: 2011

In this work, we have synthesized highly ordered mesoporous NiO materials by a nanocasting method using mesoporous silica KIT-6 as the hard templates. Mesoporous NiO particles were characterized by small angle X-ray diffraction (XRD), nitrogen adsorption/desorption, and transmission electron microscopy (TEM). The results demonstrated that the as-prepared mesoporous NiO had an ordered Ia3d symmetric mesostructure, with a high surface area of 96 m 2/g. Mesoporous NiO materials were tested as an anode material for lithium ion batteries, exhibiting much lower activation energy (20.75 kJ mol-1) compared to the bulk NiO (45.02 kJ mol-1). We found that the mesoporous NiO electrode has higher lithium intercalation kinetics than its bulk counterpart. The specific capacity of mesoporous NiO after 50 cycles was maintained 680 mAh/g at 0.1 C, which was much higher than that of the commercial bulk NiO (188 mAh/g). Furthermore, at a high rate of 2C, the discharge capacity of mesoporous NiO was as high as 515 mAh/g, demonstrating the potential to be used for high power lithium ion batteries. © The Royal Society of Chemistry 2011.

Kang M.,University of Ulsan | Kim J.,University of Ulsan | Kim J.-M.,University of Ulsan | Tan A.C.C.,Queensland University of Technology | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2015

This paper proposes a highly reliable fault diagnosis approach for low-speed bearings. The proposed approach first extracts wavelet-based fault features that represent diverse symptoms of multiple low-speed bearing defects. The most useful fault features for diagnosis are then selected by utilizing a genetic algorithm (GA)-based kernel discriminative feature analysis cooperating with one-against-all multicategory support vector machines (OAA MCSVMs). Finally, each support vector machine is individually trained with its own feature vector that includes the most discriminative fault features, offering the highest classification performance. In this study, the effectiveness of the proposed GA-based kernel discriminative feature analysis and the classification ability of individually trained OAA MCSVMs are addressed in terms of average classification accuracy. In addition, the proposed GA-based kernel discriminative feature analysis is compared with four other state-of-the-art feature analysis approaches. Experimental results indicate that the proposed approach is superior to other feature analysis methodologies, yielding an average classification accuracy of 98.06% and 94.49% under rotational speeds of 50 revolutions-per-minute (RPM) and 80 RPM, respectively. Furthermore, the individually trained MCSVMs with their own optimal fault features based on the proposed GA-based kernel discriminative feature analysis outperform the standard OAA MCSVMs, showing an average accuracy of 98.66% and 95.01% for bearings under rotational speeds of 50 RPM and 80 RPM, respectively. © 2014 IEEE.

Jia B.,Jilin University | Cheong G.-W.,Gyeongsang National University | Zhang S.,Jilin University
Extremophiles | Year: 2013

Enzymes from many archaea colonizing extreme environments are of great interest because of their potential for various biotechnological processes and scientific value of evolution. Many enzymes from archaea have been reported to catalyze promiscuous reactions or moonlight in different functions. Here, we summarize known archaeal enzymes of both groups that include different kinds of proteins. Knowledge of their biochemical properties and three-dimensional structures has proved invaluable in understanding mechanism, application, and evolutionary implications of this manifestation. In addition, the review also summarizes the methods to unravel the extra function which almost was discovered serendipitously. The study of these amazing enzymes will provide clues to optimize protein engineering applications and how enzymes might have evolved on Earth. © 2012 Springer Japan.

Limkatanyu S.,Prince of Songkla University | Damrongwiriyanupap N.,University of Phayao | Kwon M.,Gyeongsang National University | Ponbunyanon P.,Prince of Songkla University
ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik | Year: 2015

In this paper, the exact element stiffness matrix for a beam on Winkler-Pasternak foundation and the fixed-end force vector due to a linearly distributed load are alternatively derived based on the virtual force principle. The exact element flexibility matrix is at the core of the derivation of the exact element stiffness matrix and is formulated based on the exact force interpolation functions. The virtual force principle is employed to reveal the governing differential compatibility equations as well as the associated end-boundary compatibility conditions. The exact force interpolation functions of the beam-foundation system are derived based on the analytical solution of the governing differential compatibility equations of the problem for all combinations of foundation parameters and beam rigidity. This feature is unique to this paper. The matrix virtual force equation is employed to obtain the exact element flexibility matrix using the exact force interpolation functions. The so-called "natural" element stiffness matrix is obtained by inverting the exact element flexibility matrix. Three numerical examples confirm the accuracy and the efficiency of the natural beam element on Winkler-Pasternak foundation and show the deficiency of the widely used Winkler foundation model. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kim J.,Gyeongsang National University | Kwon M.,Gyeongsang National University | Jung W.,Gangneung - Wonju National University | Limkatanyu S.,Prince of Songkla University
Construction and Building Materials | Year: 2013

This paper performs experimental and numerical studies on the seismic performance of non-seismically detailed RC columns retrofitted with the proposed GFRP strengthening device. The primary goal of this study was to improve the shear strength and ductility of weak-in-shear columns. It was proposed a strengthening device that was consisted of a prefabricated GFRP composite sheet and aluminum clip connectors. This device was designed to speed up the installation time and to minimize the disturbance to adjacent walls and non-structural components. Efficiency of the proposed GFRP strengthening installation is evaluated through a series of experiments on non-strengthened and strengthened 3:4 scale RC column specimens. Comparisons between experimental results of the non-strengthened and strengthened column specimens are conducted in terms of column strength, ultimate displacement ductility, amount of hysteretic dissipated energy, and column shear behavior. So, comparisons focused on ultimate displacement ductility and hysteretic dissipated energy. A series of finite element analyses are performed to confirm the efficiency of the proposed GFRP strengthening device. © 2013 Elsevier Ltd. All rights reserved.

Park J.,Gyeongsang National University | Kim J.-S.,Advanced Materials and System Team | Park J.-W.,Gyeongsang National University | Nam T.-H.,Gyeongsang National University | And 5 more authors.
Electrochimica Acta | Year: 2013

New emerging large scale battery market has demanded low cost and high power or energy density materials. Sodium (Na) is a promising candidate for an anode material because of its low cost and natural abundance. Also molybdenum disulfide (MoS2) is an attractive cathode material with layered structure. In this study a Na/MoS2 cell was assembled so as to evaluate its electrochemical properties as a rechargeable battery. In the first discharge Na/MoS2 cell showed two characteristic plateaus at 0.93 V and 0.8 V. Galvanostatic charge/discharge cycle was carried out in different voltage ranges according to the discharge depths (0.85 V and 0.4 V). The electrochemical behaviors of Na/MoS2 cells at each discharge depth were analyzed through characterization of the crystallographic changes by employing ex situ X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Finally, Na/MoS2 reaction mechanism was suggested. © 2013 Elsevier Ltd.

Kang D.,Rosalind Franklin University of Medicine and Science | Kang D.,Gyeongsang National University | Hogan J.O.,Rosalind Franklin University of Medicine and Science | Kim D.,Rosalind Franklin University of Medicine and Science
Pflugers Archiv European Journal of Physiology | Year: 2014

The goal of this study was to determine the molecular identity of a small-conductance (~5-pS) background K+ channel expressed in trigeminal ganglion (TG) neurons. We tested the hypothesis that the 5-pS channel is a K2P channel by comparing the pharmacological and single-channel properties of THIK-1 expressed in HEK293 cells. As reported earlier, whole-cell THIK-1 current was inhibited by halothane and activated by arachidonic acid. Among 25 additional modulators tested, bupivacaine (100 μM), quinidine (50 μM) and Ba2+ (3 mM) and cold (10°C) were most effective inhibitors of THIK-1 current (>50 % inhibition). In cell-attached patches with high KCl in the pipette and bath solutions, THIK-1 produced a small-conductance (~5 pS) channel with a weak inwardly rectifying current-voltage relationship. Halothane, bupivacaine and cold inhibited the single-channel activities of both THIK-1 and the 5-pS channel in TG neurons, whereas arachidonic acid augmented them. THIK-1 expressed in HEK293 cells and the 5-pS channels in TG neurons were insensitive to hypoxia. Reverse transcriptase-PCR, Western blot and immunocytochemical analyses suggested that THIK-1 mRNA and protein were expressed in TG neurons. These results show that THIK-1 is functionally expressed in TG neurons and contributes to the background K+ conductance. © 2013 Springer-Verlag.

Udomsil N.,Suranaree University of Technology | Rodtong S.,Suranaree University of Technology | Choi Y.J.,Gyeongsang National University | Hua Y.,Suranaree University of Technology | Yongsawatdigul J.,Suranaree University of Technology
Journal of Agricultural and Food Chemistry | Year: 2011

The potential of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation was elucidated. Four strains of T. halophilus isolated from fish sauce mashes were inoculated to anchovy mixed with 25% NaCl with an approximate cell count of 10 6 CFU/mL. The α-amino content of 6-month-old fish sauce samples inoculated with T. halophilus was 780-784 mM. The addition of T. halophilus MRC10-1-3 and T. halophilus MCD10-5-10 resulted in a reduction of histamine (P < 0.05). Fish sauce inoculated with T. halophilus showed high contents of total amino acids with predominantly high glutamic acid. Major volatile compounds in fish sauce were 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde. T. halophilus-inoculated fish sauce samples demonstrated the ability to reduce dimethyl disulfide, a compound contributing to a fecal note. The use of T. halophilus for fish sauce fermentation improves amino acid profiles and volatile compounds as well as reduces biogenic amine content of a fish sauce product. © 2011 American Chemical Society.

Wang B.,University of Technology, Sydney | Wang Y.,University of Technology, Sydney | Park J.,Gyeongsang National University | Ahn H.,Gyeongsang National University | Wang G.,University of Technology, Sydney
Journal of Alloys and Compounds | Year: 2011

Co3O4/graphene nanocomposite material was prepared by an in situ solution-based method under reflux conditions. In this reaction progress, Co2+ salts were converted to Co3O4 nanoparticles which were simultaneously inserted into the graphene layers, upon the reduction of graphite oxide to graphene. The prepared material consists of uniform Co3O4 nanoparticles (15-25 nm), which are well dispersed on the surfaces of graphene nanosheets. This has been confirmed through observations by field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The prepared composite material exhibits an initial reversible lithium storage capacity of 722 mAh g-1 in lithium-ion cells and a specific supercapacitance of 478 F g-1 in 2 M KOH electrolyte for supercapacitors, which were higher than that of the previously reported pure graphene nanosheets and Co 3O4 nanoparticles. Co3O4/graphene nanocomposite material demonstrated an excellent electrochemical performance as an anode material for reversible lithium storage in lithium ion cells and as an electrode material in supercapacitors. © 2011 Elsevier B.V. All Rights Reserved.

Wang Y.,University of Technology, Sydney | Sun B.,University of Technology, Sydney | Park J.,Gyeongsang National University | Kim W.-S.,Daejung Energy Materials Co. | And 2 more authors.
Journal of Alloys and Compounds | Year: 2011

Nanosize carbon coated LiFePO4 cathode material was synthesized by in situ polymerization. The as-prepared LiFePO4 cathode material was systematically characterized by X-ray diffraction, thermogravimetric- differential scanning calorimetry, X-ray photo-electron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy techniques. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images revealed that the morphology of the LiFePO4 consists of primary particles (40-50 nm) and agglomerated secondary particles (100-110 nm). Each particle is evenly coated with an amorphous carbon layer, which has a thickness around 3-5 nm. The electrochemical properties were examined by cyclic voltammetry and charge-discharge testing. The as-prepared LiFePO4 can deliver an initial discharge capacity of 145 mAh/g, 150 mAh/g, and 134 mAh/g at 0.2 C, 1 C, and 2 C rates, respectively, and exhibits excellent cycling stability. At a higher C-rate (5 C) a slight capacity loss could be found. However after being charge-discharge at lower C-rates, LiFePO4 can be regenerated and deliver the discharge capacity of 145 mAh/g at 0.2 C. © 2010 Elsevier B.V. All rights reserved.

Lee H.J.,Chung - Ang University | Jeong S.E.,Chung - Ang University | Kim P.J.,Gyeongsang National University | Madsen E.L.,Cornell University | Jeon C.O.,Chung - Ang University
Frontiers in Microbiology | Year: 2015

The communities and abundances of methanotrophs and methanogens, along with the oxygen, methane, and total organic carbon (TOC) concentrations, were investigated along a depth gradient in a flooded rice paddy. Broad patterns in vertical profiles of oxygen, methane, TOC, and microbial abundances were similar in the bulk and rhizosphere soils, though methane and TOC concentrations and 16S rRNA gene copies were clearly higher in the rhizosphere soil than in the bulk soil. Oxygen concentrations decreased sharply to below detection limits at 8 mm depth. Pyrosequencing of 16S rRNA genes showed that bacterial and archaeal communities varied according to the oxic, oxic-anoxic, and anoxic zones, indicating that oxygen is a determining factor for the distribution of bacterial and archaeal communities. Aerobic methanotrophs were maximally observed near the oxic-anoxic interface, while methane, TOC, and methanogens were highest in the rhizosphere soil at 30-200 mm depth, suggesting that methane is produced mainly from organic carbon derived from rice plants and is metabolized aerobically. The relative abundances of type I methanotrophs such as Methylococcus, Methylomonas, and Methylocaldum decreased more drastically than those of type II methanotrophs (such as Methylocystis and Methylosinus) with increasing depth. Methanosaeta and Methanoregula were predominant methanogens at all depths, and the relative abundances of Methanosaeta, Methanoregula, and Methanosphaerula, and GOM_Arc_I increased with increasing depth. Based on contrasts between absolute abundances of methanogens and methanotrophs at depths sampled across rhizosphere and bulk soils (especially millimeter-scale slices at the surface), we have identified populations of methanogens (Methanosaeta, Methanoregula, Methanocella, Methanobacterium, and Methanosphaerula), and methanotrophs (Methylosarcina, Methylococcus, Methylosinus, and unclassified Methylocystaceae) that are likely physiologically active in situ. © 2015 Lee, Jeong, Kim, Madsen and Jeon.

Jung D.,Gyeongsang National University | Chamura R.,Toho University | Habata Y.,Toho University | Lee S.S.,Gyeongsang National University
Inorganic Chemistry | Year: 2011

A large 40-membered N4O4S4 macrocycle (L2) was obtained through a 2:2 cyclization of the corresponding dithiol and dichloride as a minor product during the preparation of a 20-membered N2O2S2 macrocycle (L1, 1:1 cyclization product). Each macrocycle was successfully separated from the mixed products and identified. The larger macrocycle L2 allowed the preparation of its dimercury(II) complex, adopting a one-dimensional (1D) stairway-like polymeric chain linked with the anion. A monomercury(II) complex of the smaller macrocycle L1 was also prepared. Both complexes and the larger macrocycle L2 were structurally characterized by the single crystal X-ray analysis. © 2011 American Chemical Society.

Shim W.-B.,Gwangju Institute of Science and Technology | Shim W.-B.,Gyeongsang National University | Mun H.,Gwangju Institute of Science and Technology | Joung H.-A.,Gwangju Institute of Science and Technology | And 3 more authors.
Food Control | Year: 2014

In this study, we developed a chemiluminescence competitive aptamer assay for aflatoxin B1 (AFB1) using a hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme (HRP-DNAzyme) linked with an aptamer specific to AFB1. Single, double, and triple HRP-DNAzymes coupled to the AFB1 aptamer were tested, and the AFB1 aptamer linked with double HRP-DNAzymes that produced sufficient chemiluminescence (CL) values when binding to AFB1-ovalbumin (OVA) used as a coating antigen, was selected. Under conditions optimized by testing key parameters, the aptamer assay exhibited a wide dynamic range from 0.1 to 10ng/mL and showed a limit of detection of 0.11ng/mL. Cross-reaction to aflatoxin G1, aflatoxin M1, and zearalenone was observed but no cross-reaction to other mycotoxins or the herbicide (atrazine) was observed. Aqueous methanol (20%) gave a good extraction efficiency and the matrix influence from corn extracts was successfully reduced through 4-fold dilution with water. Recovery from spiked corn samples averaged from 60.4 to 105.5%. Thus, the aptamer linked with HRP-DNAzymes can be useful as a reagent in the development of a biosensor for the rapid and simple detection of AFB1. Results from this study provide the basis for research into the development of various aptasensors for AFB1 analysis in foods. © 2013.

Wang G.,University of Technology, Sydney | Liu H.,University of Queensland | Liu J.,University of Queensland | Qiao S.,University of Queensland | And 3 more authors.
Advanced Materials | Year: 2010

Hexagonally ordered mesoporous LiFePO4/C nanocomposites can be synthesised with LiFePO4 nanoparticles embedded in an interconnected carbon framework. Mesoporous LiFePO4/C nanocomposites exhibit superior electrochemical performance and ultra-high specific power density, which makes this architecture suitable for high power applications such as HEVs and stationary energy storage for smart grids. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ryu H.,Gyeongsang National University | Park K.-M.,Gyeongsang National University | Ikeda M.,Chiba Institute of Technology | Habata Y.,Toho University | Lee S.S.,Gyeongsang National University
Inorganic Chemistry | Year: 2014

A 20-membered O4S2 macrocycle (L2) was synthesized as a ditopic ligating system toward hard and soft metal ions simultaneously. Five complexes (3-7) of L2 with different structures and coordination modes, including discrete to infinite forms, mono- to heteronuclear, and endo- to exo- and endo/exocoordination, were prepared and structurally characterized. First, the reaction of L2 with Pb(ClO4)2·3H2O afforded a typical endocyclic mononuclear perchlorato complex [Pb(L2)(ClO 4)2] (3) in which one lead(II) is surrounded by the macrocycle adopting a "tight and bent" conformation. Meanwhile, the reaction with a softer metal salt AgNO3 resulted in the formation of the dinuclear bis(macrocycle) complex [Ag2(L2) 2(NO3)2] (4) in which two exocyclic silver(I) ions are doubly linked by two nitrate ions. The treatment of L2 with CuI gave a mixture of the exocyclic monomer complex [Cu(L2)I] (5) and the exocyclic dimer complex [(Cu2I2)(L2) 2] (6), which were separated manually because of their brick and rhomboid shapes of the crystals, respectively. Furthermore, the reaction of L2 with a mixture of CuI and NaI afforded a photoluminescent heteronuclear complex [Na2(Cu6I8)(L 2)2(CH3CN)4]n (7) in the endo/exocyclic coordination mode. In this case, the endocyclic sodium(I) complex units are linked by the double-open cubanes-type cluster Cu6I 8, yielding a two-dimensional network. The structural and binding properties of the complex of L2 with silver(I) nitrate in solution were monitored by the NMR titration. Photophysical and thermal properties for complex 7 were also investigated and discussed. © 2014 American Chemical Society.

Wang B.,University of Technology, Sydney | Park J.,Gyeongsang National University | Su D.,University of Technology, Sydney | Wang C.,Yangzhou University | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

A CoS 2-graphene nanocomposite was prepared by a facile solvothermal method. FESEM and TEM analyses have confirmed that CoS 2 nanoparticles with sizes of 5-15 nm are densely anchored on graphene nanosheets. The as-prepared nanocomposite was electrochemically tested as an electrode material for supercapacitors. The CoS 2-graphene nanocomposite exhibited specific capacitances of 314 F g -1 in the aqueous electrolyte and 141 F g -1 in the organic electrolyte at a current rate of 0.5 A g -1 with excellent cycling stability. The electrochemical performance of the nanocomposite has been significantly improved, compared to bare graphene nanosheets and CoS 2 nanoparticles. This could be credited to the 3D nanoarchitecture, in which CoS 2 nanoparticles were sandwiched between graphene nanosheets, and the additional electrochemical contribution of the decorated CoS 2 nanoparticles. © 2012 The Royal Society of Chemistry.

Lee S.-G.,Gyeongsang National University | Park K.-M.,Gyeongsang National University | Habata Y.,Toho University | Lee S.S.,Gyeongsang National University
Inorganic Chemistry | Year: 2013

A 20-membered N2O2S2 macrocycle (L 1) and a 40-membered N4O4S4 macrocycle (L2) obtained from the mixed products via respective [1:1] and [2:2] cyclization are employed, and a comparative investigation of the coordination behavior of these macrocyclic ligands with nickel(II), cadmium(II), and silver(I) is reported. The X-ray structures of seven complexes (1-7) have been determined, and a range of structural types and coordination modes, including mono- to multinuclear and endo- to exocyclic coordination, is presented. The cation-dependent endocyclic 1:1 (metal-to-ligand) complex [Ag(L1)]NO3 (1) and a sandwich-like 1:2 [Cd(L 1)2](NO3)2 (2) complex exhibiting different stoichiometries and metal positions in the complexes were obtained by the reactions of the smaller macrocycle L1 with AgNO3 and Cd(NO3)2, respectively. Meanwhile, the reactions of L 1 with Ni(ClO4)2·6H2O and Ni(NO3)2·6H2O afforded the anion-dependent perching-type mononuclear solvato-complex [Ni(L 1)(CH3CN)3](ClO4) 2·2CH3CN (3) and the sandwich-like complex [Ni(L1)2(NO3)2] (4), respectively. In the complexations of the larger macrocycle L2 with AgNO 3, two endocyclic dinuclear complexes [Ag2(L 2)(CH3CN)2](NO3)2 (5) and [Ag2(L2)](NO3)2 (6) with different coordination environments were isolated as a kinetic (5) and thermodynamic controlled (6) products in neutral condition. The identical reaction in acidic condition afforded a stairtype one-dimensional (1-D) coordination polymer {[Ag2(H4L2)(μ2-NO 3)(NO3)2](NO3)3· CH3CN·3H2O}n (7) in which the disilver(I) complex cation units are connected by nitrate ions. From these results, the effects of the cation, anion, and size ratio on the topologies of the resulting solid complexes are discussed. NMR titrations of L1 and L2 with silver(I) nitrate were also carried out to explore their complexation behaviors in solution and for comparison with the solid state structures. © 2013 American Chemical Society.

Song J.Y.,Gyeongsang National University | Mattson N.S.,Cornell University | Jeong B.R.,Gyeongsang National University
Plant Cell, Tissue and Organ Culture | Year: 2011

Leaf, petal, petiole, and intermodal stems of six chrysanthemum cultivars were incubated on a medium supplemented with 0.00-6. 66 μM benzyladenine (BA) either alone or in combination with 2.85-8.56 μM indoleacetic acid (IAA), and 0.46 μM kinetin (Kin). Significant differences in frequency of regeneration were observed among different cultivars when grown on media containing different plant growth regulators (PGRs). The highest frequency of regeneration was observed for cv. Brighton followed by cvs. Dark Roanoke and Tahoe. Low frequencies of shoot organogenesis were observed for cvs. Dark Orange Cupertino, Hudson Bay, and Ivory Eugene. Among different explants, petals exhibited the highest frequencies of shoot organoenesis and mean number of shoots per explant. Regenerated shoots of cv. Brighton transferred onto a medium containing 2.85-8.56 μM IAA developed highest frequency of roots (100%) with a mean of 7.6 roots per shoot. Well-rooted shoots transferred to plastic pots containing a soil mix were kept in a growth room for 1 week, and then moved to the greenhouse for further growth and development. © 2011 Springer Science+Business Media B.V.

Yoon S.,North Carolina State University | Rhee I.,North Carolina State University | Jung B.C.,Gyeongsang National University | Daneshrad B.,University of California at Los Angeles | Kim J.H.,Boeing Company
Proceedings - IEEE INFOCOM | Year: 2011

A practical protocol jointly considering PHY and MAC for MIMO based concurrent transmissions in wireless ad hoc networks, called Contrabass, is presented. Concurrent transmissions refer to simultaneous transmissions by multiple nodes over the same carrier frequency within the same interference range. Contrabass is the first-to-date open-loop based concurrent transmission protocol which implements simultaneous channel training for concurrently transmitting links without any control message exchange. Its MAC protocol is designed for each active transmitter to independently decide to transmit with near optimal transmission probability. Contrabass maximizes the number of successful concurrent transmissions, thus achieving very high aggregate throughput, low delays and scalability even under dynamic environments. The design choices of Contrabass are deliberately made to enable practical implementation which is demonstrated through GNURadio implementation and experimentation. © 2011 IEEE.

Youn S.J.,Northwestern University | Youn S.J.,Gyeongsang National University | Fischer M.H.,Cornell University | Fischer M.H.,ETH Zurich | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

In clean inversion symmetric materials, spin-orbit coupling is not thought to have a pronounced effect on spin-singlet superconductivity. Here we show that, for the recently discovered pnictide superconductor SrPtAs, this is not the case. In particular, for spin-singlet superconductivity in SrPtAs, strong spin-orbit coupling leads to a significant enhancement of both the spin susceptibility and the paramagnetic limiting field with respect to that usually expected for spin-singlet superconductors. The underlying reason for this is that, while SrPtAs has a center of inversion symmetry, it contains weakly coupled As-Pt layers that do not have inversion symmetry. This local inversion-symmetry breaking allows for a form of spin-orbit coupling that dramatically effects superconductivity. These results indicate that caution should be used when interpreting measurements of the spin susceptibility and the paramagnetic limiting field if superconductivity resides in regions of locally broken inversion symmetry. © 2012 American Physical Society.

Moon H.,Korea Institute of Construction Technology | Kim H.,Gyeongsang National University | Kim C.,Gyeongnam National University of Science and Technology | Kang L.,Gyeongsang National University
Automation in Construction | Year: 2014

Schedule-workspace interference is generated when workspaces that share parallel schedules and are physically adjacent to one another exist simultaneously. When workspace interference is generated, securing work performance safety is difficult and constructability can deteriorate due to increased collision risk between resources. The objective of this study is to realize an active simulation system based on building information modeling (BIM) after constructing a genetic algorithm (GA) process for an alternative schedule that minimizes the simultaneous interference level of the schedule-workspace. To accomplish this task, the impact factor of workspace interference, which simultaneously considers schedule overlap and adjacency, was analyzed. From the impact factor, an optimized algorithm based on a location-constraint GA that can minimize workspace interference is suggested. The GA visually simulates the optimization level of the execution schedule compared to the initial plan through interlock with four-dimensional (4D) computer-aided design (CAD). A 4D CAD system that can analyze workspace interference by a GA was developed, and for the developed algorithm and system, a case verification was attempted for a railroad construction project. The results show how a simple visualization-oriented BIM system can be extended to an active schedule management system equipped with decision-making functions of workspace analysis. © 2013 Elsevier B.V.

Won S.W.,Gyeongsang National University | Kwak I.S.,Engineering R andnter | Yun Y.-S.,Gyeongsang National University | Yun Y.-S.,Chonbuk National University
Bioresource Technology | Year: 2014

The present study is aimed at understanding the role of bacterial biomass in functionalizing polyethylenimine (PEI)-coated bacterial biosorbent fiber (PBBF). To make PBBF, chitosan/biomass composite fiber was coated with PEI and then cross-linked by glutaraldehyde. The role of biomass in the fiber was investigated through sorption experiments and SEM, FTIR and XPS analyses with differently prepared fiber sorbents. In the case that the chitosan fiber was made without the biomass, it could not be coated with PEI. Meanwhile, the chitosan/biomass composite fiber could successfully coated with PEI and primary amine groups were significantly increased on the surface of the fiber. Therefore, the biomass should be essential to make PEI-reinforced chitosan fiber. © 2014 Elsevier Ltd.

Kim D.,Rosalind Franklin University of Medicine and Science | Kang D.,Gyeongsang National University
Pflugers Archiv European Journal of Physiology | Year: 2015

Two-pore domain K+ (K2P) channels are involved in a variety of physiological processes by virtue of their high basal activity and sensitivity to various biological stimuli. One of these processes is secretion of hormones and transmitters in response to stimuli such as hypoxia, acidosis, and receptor agonists. The rise in intracellular [Ca2+] ([Ca2+]i) that is critical for the secretory event can be achieved by several mechanisms: (a) inhibition of resting (background) K+ channels, (b) activation of Na+/Ca2+-permeable channels, and (c) release of Ca2+ from intracellular stores. Here, we discuss the role of TASK and TREK in stimulus-secretion mechanisms in carotid body chemoreceptor cells and adrenal medullary/cortical cells. Studies show that stimuli such as hypoxia and acidosis cause cell depolarization and transmitter/hormone secretion by inhibition of TASK or TREK. Subsequent elevation of [Ca2+]i produced by opening of voltage-dependent Ca2+ channels then activates a Na+-permeable cation channel, presumably to help sustain the depolarization and [Ca2+]i. Agonists such as angiotensin II may elevate [Ca2+]i via multiple mechanisms involving both inhibition of TASK/TREK and Ca2+ release from internal stores to cause aldosterone secretion. Thus, inhibition of resting (background) K+ channels and subsequent activation of voltage-gated Ca2+ channels and Na+-permeable non-selective cation channels may be a common ionic mechanism that lead to hormone and transmitter secretion. © 2014, Springer-Verlag Berlin Heidelberg.

Burns J.T.,University of Virginia | Kim S.,Gyeongsang National University | Gangloff R.P.,University of Virginia
Corrosion Science | Year: 2010

The effect of existing-localized corrosion on fatigue cracking of 7075-T6511 was established using crack surface marker-band analysis and a fracture mechanics model. The substantial reduction of fatigue life due to EXCO solution L-S surface pre-corrosion is nearly independent of exposure time after initial-sharp degradation, scaling with the evolution of pit-cluster size and initial stress intensity range with exposure time. Independent of exposure time, formation of a resolvable fatigue crack (∼10 μm) accounts for a similar-low (∼5%) fraction of total fatigue life at low stress range (σmax = 150 MPa, R = 0.1). Crack formation occurs at microscopic protrusions into the corroded volume. A corrosion-modified-equivalent initial flaw size (CM-EIFS); predicted with the AFGROW tool using measured initial aspect ratio, initiation cycles, and total fatigue life inputs; accurately represents the corrosion damage effect on fatigue for a range of exposures. The similar deleterious effect of several corroding environments for various-exposed surfaces is described by a lower-bound CM-EIFS with a 300 μm depth and 1200 μm surface length suggesting fatigue is governed by a microscopic pit-based topography. Either an approximate lower-bound, or specific CM-EIFS calibrated by limited measurements of fatigue life for service-environment exposed specimens, can be used to assess the impact of corrosion in a damage tolerant framework. Complexities (e.g., local H embrittlement, 3D pit geometry, topography dependent initiation, and microstructure sensitive small-crack growth) do not compromise the CM-EIFS estimation, but must be better understood for refined modeling. © 2009 Elsevier Ltd.

Chiang T.P.,National Taiwan University | Sau A.,Gyeongsang National University | Hwang R.R.,Academia Sinica, Taiwan
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

This study reports the presence of two different stable modes of bifurcation in the near field of a three-dimensional sudden contraction. To be precise, flow downstream of a symmetric sudden contraction undergoes a transition from a symmetric state to an asymmetric state through a symmetry-breaking pitchfork bifurcation following an increase in the channel aspect ratio or the Reynolds number. In addition, the oncoming (upstream) symmetry-plane flow exhibits spanwise bifurcations along the topological core lines of each of the salient roof and floor eddies. Small aspect-ratio (contraction) channels are noted to facilitate interesting splitting of the salient roof and floor eddies into multicore forms with accompanying spanwise flow bifurcations along the respective vortical core lines. Herein extensive three-dimensional simulations performed with various aspect and contraction ratios and Reynolds numbers clearly suggest that flow transition in the sudden-contraction channels should indeed occur primarily through these two generically distinct modes of bifurcation. © 2011 American Physical Society.

Sun B.,University of Technology, Sydney | Zhang J.,University of Technology, Sydney | Munroe P.,University of New South Wales | Ahn H.-J.,Gyeongsang National University | And 2 more authors.
Electrochemistry Communications | Year: 2013

NiCo2O4 nanorods were synthesized by a hydrothermal method followed by low temperature calcination. FESEM and TEM analyses confirmed that the as-prepared materials consist of a hierarchical nanorod structure. When applied as cathode catalysts in rechargeable Li-O2 batteries, NiCo2O4 nanorods exhibited a superior catalytic activity, including low charge over-potential, high discharge capacity and high-rate capability. © 2013 Elsevier B.V.

Saadati R.,Amirkabir University of Technology | Saadati R.,Shomal University | Cho Y.J.,Gyeongsang National University | Vahidi J.,Shomal University
Computers and Mathematics with Applications | Year: 2010

The purpose of this paper is first to introduce the notation of intuitionistic random normed spaces, and then by virtue of this notation to study the stability of a quartic functional equation in the setting of these spaces under arbitrary triangle norms. Then we prove the stability of above quartic functional equation in non-Archimedean random normed spaces. Furthermore, the interdisciplinary relation among the theory of random spaces, the theory of non-Archimedean spaces, the theory of intuitionistic spaces and the theory of functional equations are also presented in the paper. © 2010 Elsevier Ltd. All rights reserved.

Ro K.,Gyeongsang National University | Zhu B.,Tsinghua University
Journal of Fluids Engineering, Transactions of the ASME | Year: 2013

In this study, a reciprocating-type water turbine model that applies the principle of the Weis-Fogh mechanism was proposed, and the model's unsteady flow field was calculated by an advanced vortex method. The primary conditions were as follows: wing chord C=1, wing shaft stroke length hs=2.5C, and the maximum opening angle of the wing α=36 deg. The dynamic characteristics and unsteady flow fields of a Weis-Fogh type water turbine were investigated with velocity ratios U/V = 1.0 ∼ 3.0. Force coefficients Cu and Cv acting on the wing in the U and V directions, respectively, were found to have a strong correlation each other. The size of a separated region on the back face of the wing increased as the velocity ratio increased and as the wing approached the opposite wall. The rapid drop in Cv during a stroke increased as the velocity ratio increased, and the average Cu and Cv increased as the velocity ratio increased. The maximum efficiency of this water turbine was 14.1% at U/V = 2.0 for one wing. © 2013 by ASME.

Giesy S.L.,Cornell University | Yoon B.,Cornell University | Currie W.B.,Cornell University | Kim J.W.,Gyeongsang National University | Boisclair Y.R.,Cornell University
Endocrinology | Year: 2012

In rodents and primates, insulin resistance develops during pregnancy and fades after parturition. In contrast, dairy cows and other ruminants maintain insulin resistance in early lactation (EL). This adaptation favors mammary glucose uptake, an insulin-independent process, at a time when the glucose supply is scarce. Reduction in circulating levels of the insulin-sensitizing hormone adiponectin promotes insulin resistance in other species, but whether it contributes to insulin resistance in EL dairy cows is unknown. To address this question, plasma adiponectin was measured in high-yielding dairy cows during the transition from late pregnancy (LP) to EL. Plasma adiponectin varied in quadratic fashion with the highest levels in LP, a maximal reduction of 45% on the day after parturition and a progressive return to LP values over the next 8 wk. Adiponectin circulated nearly exclusively in high molecular weight complexes in LP, and this distribution remained unaffected in EL. The reduction of plasma adiponectin in EL occurred without changes in adiponectin mRNA in adipose tissue but was associated with repression of the expression of proteins associated with the endoplasmic reticulum and involved in assembly of adiponectin oligomers. Finally, EL increased the expression of the adiponectin receptor 1 in muscle and adiponectin receptor 2 in liver but had no effect on the expression of these receptors in adipose tissue and in the mammary gland. These data suggest that reduced plasma adiponectin belongs to the subset of hormonal adaptations in EL dairy cows facilitating mammary glucose uptake via promotion of insulin resistance. Copyright © 2012 by The Endocrine Society.

Sun B.,University of Technology, Sydney | Wang B.,University of Technology, Sydney | Su D.,University of Technology, Sydney | Xiao L.,University of Technology, Sydney | And 2 more authors.
Carbon | Year: 2012

Graphene nanosheets have been investigated as cathode catalysts for lithium-air batteries with alkyl carbonate electrolyte. Field emission scanning electron microscopy, transmission electron microscope and Raman spectroscopy have confirmed the high quality of the as-prepared graphene nanosheets and the surface analysis has identified the mesoporous characteristic of graphene nanosheets. The electrochemical properties of graphene nanosheets as cathode catalysts in lithium-air batteries were evaluated by a galvanostatic charge/discharge testing. The reaction products on the graphene nanosheets cathode were analyzed by X-ray diffraction and Fourier transform infrared spectroscopy. The graphene nanosheet electrodes exhibited a much better cycling stability and lower overpotential than that of the Vulcan XC-72 carbon. This work demonstrated that graphene nanosheets could be an efficient catalyst for lithium-air batteries. © 2011 Elsevier Ltd. All rights reserved.

Kim H.-E.,Queensland University of Technology | Tan A.C.C.,Queensland University of Technology | Mathew J.,Queensland University of Technology | Choi B.-K.,Gyeongsang National University
Expert Systems with Applications | Year: 2012

In condition-based maintenance (CBM), effective diagnostic and prognostic tools are essential for maintenance engineers to identify imminent fault and predict the remaining useful life before the components finally fail. This enables remedial actions to be taken in advance and reschedule of production if necessary. All machine components are subjected to degradation processes in real environments and they have certain failure characteristics which can be related to the operating conditions. This paper describes a technique for accurate assessment of the remnant life of bearings based on health state probability estimation and historical knowledge embedded in the closed loop diagnostics and prognostics system. The technique uses the Support Vector Machine (SVM) classifier as a tool for estimating health state probability of machine degradation process to provide long term prediction. To validate the feasibility of the proposed model, real life fault historical data from bearings of High Pressure-Liquefied Natural Gas (HP-LNG) pumps were analysed and used to obtain the optimal prediction of remaining useful life (RUL). The results obtained were very encouraging and showed that the proposed prognosis system based on health state probability estimation has the potential to be used as an estimation tool for remnant life prediction in industrial machinery. © 2011 Elsevier Ltd. All rights reserved.

Moon H.,Korea Institute of Construction Technology | Kim H.,Gyeongsang National University | Kamat V.R.,University of Michigan | Kang L.,Gyeongsang National University
Journal of Computing in Civil Engineering | Year: 2015

As building information modeling (BIM) systems continue to be widely adopted, there is an increasing demand for an active construction schedule management system with more advanced decision-making capabilities. For example, if overlapping between construction activities is significant, the performance of construction operations for the corresponding activities may deteriorate. Thus, a viable construction schedule should be formulated in order to minimize overlapping of proximate construction activities. An active system can be regarded as a certain solution for this issue. The purpose of this study is to develop a systematic methodology and computer system for an optimal construction schedule simulation that minimize overlapping activities for the enhancement of a project's operational performance. This study centers on identifying overlapping activities, applying fuzzy theory, and analyzing risk levels for schedule overlap issues. In addition, genetic algorithm (GA) theory is adopted for the minimization of the overlapping of highly risky activities. Finally, an optimal construction schedule that minimizes overlapping activities is suggested. The optimal schedule is visualized in a BIM-based four-dimensional (4D) computer-aided design (CAD) environment. The 4D CAD system developed in this study includes fuzzy and GA analysis functions with a schedule simulator. A case study on an actual project is introduced to validate the effectiveness of the proposed methodology. © 2014 American Society of Civil Engineers.

Munkhbayar B.,Gyeongsang National University | Nine M.J.,Gyeongsang National University | Jeoun J.,Gyeongsang National University | Ji M.,Young Jin Forgin Co. | And 2 more authors.
Journal of Power Sources | Year: 2013

The article reports a nanocomposite (graphene and tungsten (GN-W)) successfully used as an alternative to a conventional Pt counter electrode in dye-sensitised solar cells (DSSCs). The dispersibility of the GN structure in ethanol was enhanced by acid oxidation and planetary ball milling. Raw, purified and purified and ground GN structures were spin coated onto fluorine-doped tin oxide (FTO) glass substrates and examined as catalytic films on the counter electrodes of DSSCs. Purified and ground GNs exhibited the best photovoltaic performance (4.55%) among these structures. The grinding method was found effective for upgrading the dispersibility of GNs in a base fluid and the photovoltaic efficiency results. Based on the photovoltaic efficiency results of the DSSCs with different GN structures, the purified and ground GN structure was selected and incorporated with tungsten. A composite film of GN-W was used as a catalytic film on the counter electrode of a DSSC. The DSSC fabricated with the GN-W composite counter electrode achieved a photovoltaic efficiency of 5.88%. This performance is comparable to that of a DSSC with a standard Pt counter electrode (5.92%).© 2012 Published by Elsevier Inc. All rights reserved.

Kam S.C.,Gyeongsang National University | Han D.H.,Sungkyunkwan University | Lee S.W.,Sungkyunkwan University
Journal of Sexual Medicine | Year: 2011

Introduction. Premature ejaculation (PE) is the most prevalent male ejaculation disorder. The premature ejaculation diagnostic tool (PEDT) was developed to systematically apply the DSM-IV-TR criteria in diagnostic PE. Aims. To evaluate the diagnostic value of the PEDT and its association with intravaginal ejaculatory latency time (IELT). Methods. (i) Korean validation of PEDT: data was collected from men interviewed by one of the two clinical experts, who made a diagnostic of present or absence of PE, using DSM-IV-TR criteria. A total of 103 patients with PE and 100 men without PE were enrolled into the study and requested to complete the PEDT; and (ii) The correlation between IELT and PEDT: 200 participants were enrolled and each participant was asked to make out PEDT. All participants were requested to measure IELT. Main Outcome Measures. Validity and reliability of the PEDT and its association with IELT. Results. The geometric mean IELT of the PE group was 115.37±78.14 seconds. The number of men reporting IELTs of <1, 1 to ≤2, and >2 minutes were 28 (28.6%), 29 (29.6%), and 41 (41.8%), respectively. The Cronbach's alpha score was calculated as 0.93, showing adequate internal consistency. The test-retest correlation coefficients of each item were higher than 0.72 and the correlation coefficients of the total score was 0.88. (P<0.001) Sensitivity and specificity analyses suggested a score of ≤8 indicated no PE, 9 and 10 probable PE, and ≥11 PE. The PEDT total score and IELT showed an adequate negative correlation. (ρ=-0.77, P<0.0001) also, the PEDT total score of the PE subgroup (IELT≤2 minutes) and IELT showed a negative correlation. (ρ=-0.6, P<0.0001) Conclusions. The PEDT was highly effective in detecting the presence of PE. The result of our study supports its validity as a diagnostic tool in the clinical setting. © 2010 International Society for Sexual Medicine.

Wang C.,Gyeongsang National University | Yoon S.-H.,Gyeongsang National University | Jang H.-J.,Gyeongsang National University | Chung Y.-R.,Gyeongsang National University | And 3 more authors.
Metabolic Engineering | Year: 2011

Sesquiterpenes are important materials in pharmaceuticals and industry. Metabolic engineering has been successfully used to produce these valuable compounds in microbial hosts. However, the microbial potential of sesquiterpene production is limited by the poor heterologous expression of plant sesquiterpene synthases and the deficient FPP precursor supply. In this study, we engineered E. coli to produce α-farnesene using a codon-optimized α-farnesene synthase and an exogenous MVA pathway. Codon optimization of α-farnesene synthase improved both the synthase expression and α-farnesene production. Augmentation of the metabolic flux for FPP synthesis conferred a 1.6- to 48.0-fold increase in α-farnesene production. An additional increase in α-farnesene production was achieved by the protein fusion of FPP synthase and α-farnesene synthase. The engineered E. coli strain was able to produce 380.0. mg/L of α-farnesene, which is an approximately 317-fold increase over the initial production of 1.2. mg/L. © 2011 Elsevier Inc.

Ali T.,Gyeongsang National University | Kim M.O.,Gyeongsang National University
Journal of Pineal Research | Year: 2015

Alzheimer's disease (AD) is the most prevalent age-related neurodegenerative disease, pathologically characterized by the accumulation of amyloid beta (Aβ) aggregation in the brain, and is considered to be the primary cause of cognitive dysfunction. Aβ aggregates lead to synaptic disorder, tau hyperphosphorylation, and neurodegeneration. In this study, the underlying neuroprotective mechanism of melatonin against Aβ1-42-induced neurotoxicity was investigated in the mice hippocampus. Intracerebroventricular (i.c.v.) Aβ1-42-injection triggered memory impairment, synaptic disorder, hyperphosphorylation of tau protein, and neurodegeneration in the mice hippocampus. After 24 hr of Aβ1-42 injection, the mice were treated with melatonin (10 mg/kg, intraperitonially) for 3 wks, reversed the Aβ1-42-induced synaptic disorder via increasing the level of presyanptic (Synaptophysin and SNAP-25) and postsynaptic protein [PSD95, p-GluR1 (Ser845), SNAP23, and p-CREB (Ser133)], respectively, and attenuated the Aβ1-42-induced memory impairment. Chronic melatonin treatment attenuated the hyperphosphorylation of tau protein via PI3K/Akt/GSK3β signaling by activating the p-PI3K, p-Akt (Ser 473) and p-GSK3β (Ser9) in the Aβ1-42-treated mice. Furthermore, melatonin decreased Aβ1-42-induced apoptosis through decreasing the overexpression of caspase-9, caspase-3, and PARP-1 level. Additionally, the evaluation of immunohistochemical analysis of caspase-3, Fluorojade-B, and Nissl staining indicated that melatonin prevented neurodegeneration in Aβ1-42-treated mice. Our results demonstrated that melatonin has neuroprotective effect against Aβ1-42-induced neurotoxicity through decreasing memory impairment, synaptic disorder, tau hyperphosphorylation, and neurodegeneration via PI3K/Akt/GSK3β signaling in the Aβ1-42-treated mouse model of AD. On the basis of these results, we suggest that melatonin could be an effective, promising, and safe neuroprotective candidate for the treatment of progressive neurodegenerative disorders, such as AD. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Aoki T.,Waseda University | Aoki T.,Gyeongsang National University | Hikima J.-I.,Gyeongsang National University | Hwang S.D.,Gyeongsang National University | Jung T.S.,Gyeongsang National University
Fish and Shellfish Immunology | Year: 2013

During the past decade, huge progress has been made in research into teleost PAMPs (pathogen-associated molecule patterns) recognition receptors (PRRs). Numerous fish PRR genes have been identified, and the primordial functions of PRRs involved in the innate immune response to viral infection (especially those responsible for sensing viral RNA) have been increasingly clarified in teleosts. Particular progress has been made in our understanding of Toll-like receptors (TLRs) and retinoic acid inducible gene I (RIG-I)-like receptors (RLRs). However, there are important evolutionary differences between teleosts and mammals; for instance, seven TLR repertoires (TLR5S, -14, -19, -20, -21, -22 and -23) are present in teleosts but not in mammals, indicating that some TLRs likely possess different functions. Thus, comparison of PRRs in teleosts and mammals may help us understand the immune responses triggered by host-pathogen interactions in teleosts. In this article, the evolutionary conservations and divergences in the PRR mechanisms of teleosts and mammals are examined, with a focus on their molecular features and the recognition of viral RNA by fish TLRs and RLRs. In addition, the mechanism of type I interferon gene expression in teleosts, which is enhanced after the recognition of viral RNA by fish TLRs and RLRs, is also introduced. © 2013 Elsevier Ltd.

Ali T.,Gyeongsang National University | Badshah H.,Gyeongsang National University | Kim T.H.,Gyeongsang National University | Kim M.O.,Gyeongsang National University
Journal of Pineal Research | Year: 2015

Melatonin acts as a pleiotropic agent in various age-related neurodegenerative diseases. In this study, we examined the underlying neuroprotective mechanism of melatonin against D-galactose-induced memory and synaptic dysfunction, elevated reactive oxygen species (ROS), neuroinflammation and neurodegeneration. D-galactose was administered (100 mg/kg intraperitoneally (i.p.)) for 60 days. After 30 days of D-galactose administration, vehicle (same volume) or melatonin (10 mg/kg, i.p.) was administered for 30 days. Our behavioral (Morris water maze and Y-maze test) results revealed that chronic melatonin treatment alleviated D-galactose-induced memory impairment. Additionally, melatonin treatment reversed D-galactose-induced synaptic disorder via increasing the level of memory-related pre-and postsynaptic protein markers. We also determined that melatonin enhances memory function in the D-galactose-treated mice possibly via reduction of elevated ROS and receptor for advanced glycation end products (RAGE). Furthermore, Western blot and morphological results showed that melatonin treatment significantly reduced D-galactose-induced neuroinflammation through inhibition of microgliosis (Iba-1) and astrocytosis (GFAP), and downregulating other inflammatory mediators such as p-IKKβ, p-NF-KB65, COX2, NOS2, IL-1β, and TNFα. Moreover, melatonin lowered the oxidative stress kinase p-JNK which suppressed various apoptotic markers, that is, cytochrome C, caspase-9, caspase-3 and PARP-1, and prevent neurodegeneration. Hence, melatonin attenuated the D-galactose-induced memory impairment, neuroinflammation and neurodegeneration possibly through RAGE/NF-KB/JNK pathway. Taken together, our data suggest that melatonin could be a promising, safe and endogenous compatible antioxidant candidate for age-related neurodegenerative diseases such as Alzheimer's disease (AD). © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Jang J.H.,Gyeongsang National University | Kim H.,Gyeongsang National University | Cho J.H.,Gyeongsang National University
Fish and Shellfish Immunology | Year: 2013

Peptidoglycan recognition proteins (PGRPs) are innate immune molecules that are structurally conserved through evolution in both invertebrate and vertebrate animals. PGRPs exert diverse host-defense functions both through direct antibacterial activity and through indirect effects, including the induction of antimicrobial peptides and the modulation of inflammation and immune responses. In this study, we identified the gene encoding a long form of PGRP (OmPGRP-L1) from the rainbow trout, Oncorhynchus mykiss, and investigated whether it has immunomodulating activity in a rainbow trout hepatoma cell line RTH-149 challenged with fish pathogenic bacteria. OmPGRP-L1 contains the conserved PGRP domain and the four Zn2+-binding amino acid residues required for amidase activity. In RTH-149 cells, OmPGRP-L1 expression was increased by bacterial stimulation. Loss-of-function and gain-of-function experiments indicated that OmPGRP-L1 is involved in the expression of pro-inflammatory cytokines. Silencing of OmPGRP-L1 in RTH-149 cells challenged with Edwardsiella tarda dramatically increased the expression of IL-1β and TNF-α. In contrast, overexpression of OmPGRP-L1 or its amidase-inactive mutant OmPGRP-L1(C472S) resulted in down-regulation of IL-1β and TNF-α expression. When overexpressed in RTH-149 cells, OmPGRP-L1 inhibited NF-κB activity with or without bacterial stimulation. Collectively, these findings suggest that OmPGRP-L1 has an anti-inflammatory function, independent of its amidase activity, possibly via NF-κB inhibition in liver cells. © 2013 Elsevier Ltd.

Lee Y.-J.,Sungkyunkwan University | Lee Y.-J.,Gyeongsang National University | Wi Y.M.,Sungkyunkwan University | Kwon Y.J.,Sungkyunkwan University | And 3 more authors.
Critical Care Medicine | Year: 2015

Objective: To investigate the development of nephrotoxicity associated with colistin dose, and whether this relationship differs depending on renal function. Design: A retrospective cohort study of patients who received intravenous colistin to treat infections caused by extensively drug-resistant Gram-negative microorganisms. Adult patients receiving colistin for 72 hours or longer were included in this study. Patients who received renal replacement therapy at baseline or were administered colistin for less than 3 days were excluded. Colistin-induced nephrotoxicity was defined as a doubling of baseline serum creatinine. Colistin dosing was evaluated based on both actual body weight and ideal body weight. Setting: Single general hospital between 2010 and 2013. Patients: A total number of 475 patients received colistin therapy. Of these patients, 329 met the inclusion criteria and were included in the analysis. Interventions: None. Measurements and Main Results: One hundred forty-three patients (43.5%) experienced nephrotoxicity during colistin treatment. The median onset time of nephrotoxicity was 6 days (interquartile range, 4-8 days). The patients with nephrotoxicity were older. Hematocrit and serum albumin levels were lower in patients with nephrotoxicity. Median daily dosing of colistin based on ideal body weight was significantly higher in patients with nephrotoxicity than in those without nephrotoxicity (4.55 vs 4.43 mg/kg/d, respectively; p = 0.021). The cumulative dose was not different between patients with and without nephrotoxicity. In multiple logistic regression analysis, daily colistin dosing based on ideal body weight was only significantly associated with the development of nephrotoxicity in patients with an estimated glomerular filtration rate < 60 mL/min/1.73 m 2 (odds ratio, 2.34; 95% CI, 1.22-4.5). In these affected patients, based on a receiver operating characteristic plot, the optimal predictive cutoff of colistin dose for the development of nephrotoxicity was 2.87 mg/kg/d of colistin, with a sensitivity of 92.3% and a specificity of 76.7%. In patients with estimated glomerular filtration rate ≥ 60 mL/min/1.73 m 2, age, serum albumin, hematocrit, and use of glycopeptide were associated with the development of nephrotoxicity. Conclusions: Development of nephrotoxicity was significantly more strongly associated with the dose of colistin, but only in patients with an estimated glomerular filtration rate < 60 mL/min/1.73 m 2 and not in those with normal renal function. © 2015 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.

Jung T.S.,Gyeongsang National University | Kim S.K.,Gyeongsang National University | Shin H.J.,Gyeongsang National University | Jeon B.T.,Gyeongsang National University | And 2 more authors.
Liver International | Year: 2012

Background: Insulin resistance, oxidative stress, inflammation and innate immune system activation contribute to the development of non-alcoholic fatty liver disease (NAFLD) through steatosis and inflammation in the liver. The powerful antioxidant α-lipoic acid (ALA) has been shown to improve insulin sensitivity and suppress inflammatory responses. This study explores how ALA administration protects against NAFLD. Methods: Otsuka Long-Evans Tokushima Fatty (OLETF) rats were divided into two groups (treated with 200 mg/kg/day of ALA or untreated) at 12 weeks of age and sacrificed at 28 weeks of age. Results: Serum levels of insulin, free fatty acids, total cholesterol, triglyceride, leptin, IL-6 and blood glucose were decreased in ALA-treated rats. Serum adiponectin levels were higher in ALA-treated rats. ALA treatment decreased the expression of sterol regulatory element binding protein-1 and acetyl CoA carboxylase, and increased glucose transporter-4 expression in the livers of OLETF rats. Expression of the antioxidant enzymes heme oxygenase-1 and Cu/Zn-superoxide dismutase was increased in the livers of ALA-treated rats. The lipid peroxidation marker 4-hydroxynonenal was decreased in the liver of ALA-treated rats. Proteins associated with innate immune activation (Toll-like receptor-4 and high-mobility group protein box-1) and inflammatory markers (vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and cyclooxygenase-2) were decreased in the livers of ALA-treated rats. Conclusions: Chronic ALA supplementation prevents NAFLD through multiple mechanisms by reducing steatosis, oxidative stress, immune activation and inflammation in the liver. © 2012 John Wiley & Sons A/S.

Jeong M.-Y.,Gyeongsang National University | Brasselet S.,Aix - Marseille University | Cho B.R.,Korea University | Lim T.-K.,Korea University
Optics Express | Year: 2011

We present theoretical and experimental demonstrations of the electro-optic activity in crystalline molecular thin films with octupolar D3h symmetry. Applying a longitudinal electric field modulation within the molecular plane, we analyze the induced refractive index change relative to the orientation of the octupoles in their plane, and show that a maximum value is reached when one octupolar branch lies along the direction of the modulating field. These characteristics, as well as their electric field dependence, are drastically different from more traditional one-dimensional symmetry samples, bringing additional advantages related to electro-optic coupling possibilities. © 2011 Optical Society of America.

Jeong M.-Y.,Gyeongsang National University | Wu J.W.,Ewha Womans University
International Journal of Molecular Sciences | Year: 2011

In order to achieve a continuous tuning of laser emission, the authors designed and fabricated three types of cholesteric liquid crystal cells with pitch gradient, a wedge cell with positive slope, a wedge cell with negative slope, and a parallel cell. The length of the cholesteric liquid crystal pitch could be elongated up to 10 nm, allowing the lasing behavior of continuous or discontinuous spatial tuning determined by the boundary conditions of the cholesteric liquid crystal cell. In the wedge cell with positive slope, the authors demonstrated a continuous spatial laser tuning in the near full visible spectral range, with a tuning resolution less than 1 nm by pumping with only a single 355 nm laser beam. This continuous tuning behavior is due to the fact that the concentration of pitch gradient matches the fixed helical pitch determined by the cell thickness. This characteristic continuous spatial laser tuning could be confirmed again by pumping with a 532 nm laser beam, over 90 nm in the visible spectral range. The scheme of the spatial laser tuning in the wedge cell bearing a pitch gradient enabled a route to designing small-sized optical devices that allow for a wide tunability of single-mode laser emissions. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Lindoy L.F.,University of Sydney | Meehan G.V.,James Cook University | Vasilescu I.M.,James Cook University | Kim H.J.,Gyeongsang National University | And 2 more authors.
Coordination Chemistry Reviews | Year: 2010

The transition and post-transition metal ion chemistry of a wide range of potentially pentadentate dibenzo-substituted macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors is reviewed and shown to result in a diverse range of structural types. Aspects of metal ion recognition, bulk membrane transport, systems incorporating appended chromophores, a sulfate binding system, induced Cu(I)/Cu(II) redox switching, coordination polymers, and unsymmetric macrocyclic ligand systems are all discussed. © 2009 Elsevier B.V. All rights reserved.

Munkhbayar B.,Gyeongsang National University | Hwang S.,Gyeongsang National University | Kim J.,Mokpo Maritime University | Bae K.,Dae Myung GENT Co. | And 3 more authors.
Electrochimica Acta | Year: 2012

We report the successful application of multi-walled carbon nanotubes (MWCNTs) as electrocatalysts for triiodide reduction in dye-sensitized solar cells (DSSCs). To improve the photovoltaic performance of DSSCs, upgrade the quality of MWCNT structure and obtain an optimum deposition approach regarding a counter electrode, the present study was investigated. Three different MWCNT structures, raw, purified and purified and ground, were investigated as platinum (Pt) alternatives for counter electrodes in DSSCs. The counter electrodes were prepared on fluorine-doped tin oxide (FTO) glass substrates by two different techniques: spin coating from fluid-type MWCNTs and screen printing from paste-type MWCNTs. By utilizing a spin-coating technique, a DSSC that was fabricated with a purified and ground MWCNT counter electrode achieved an overall photovoltaic efficiency of 4.94%. This photovoltaic performance is comparable to that of a DSSC using a conventional "Pt" counter electrode fabricated under the same conditions. We found that the grinding method is powerful for increasing specific surface area and porosity. With this technique, macropores can be transformed into mesopores, thereby reducing the agglomeration of the MWCNTs, and with an additional modification, an increased DSSC photovoltaic efficiency results. © 2012 Elsevier Ltd.

Kim B.R.,Gyeongsang National University | Sung G.H.,Gyeongsang National University | Lee S.-G.,Gyeongsang National University | Yoon Y.J.,Gyeongsang National University
Tetrahedron | Year: 2013

Efficient and green esterification is of great importance. In this work, we demonstrate the catalyst-free esterification of alcohols by their reaction with 2-acyl-4,5-dichloropyridazin-3(2H)-ones under microwave irradiation. Aliphatic and aromatic alcohols were converted into the corresponding esters in good to excellent yields under microwave irradiation in solvent or solvent-free conditions. It is noteworthy that the reaction is catalyst-free, atom-economic, and rapid and that the process is inexpensive. © 2013 Elsevier Ltd. All rights reserved.

Chin Y.-W.,Dongguk University | Kong J.Y.,Gyeongsang National University | Han S.-Y.,Gyeongsang National University
Bioorganic and Medicinal Chemistry Letters | Year: 2013

The Fms-like tyrosine kinase 3 (FLT3), a receptor tyrosine kinase, is involved in the proliferation, differentiation and apoptosis of hematopoietic cells. FLT3 is highly overexpressed in acute myeloid leukemia (AML) of the majority of patients. Screening for flavonoids including flavones, flavanones, flavonols, and flavanonols disclosed that luteolin was potent FLT3 enzyme inhibitor. Furthermore, luteolin suppressed cell proliferation in MV4;11 cells with constitutively activated FLT3. © 2013 Elsevier Ltd. All rights reserved.

Park S.,Gyeongsang National University | Lee S.Y.,Gyeongsang National University | Lee S.S.,Gyeongsang National University
Inorganic Chemistry | Year: 2010

A range of thiaphilic mononuclear (Hg2+ and Ag+) and heterobinuclear (Ag+/Pd2+) complexes (1-6) of an NS 2- donor macrocycle L with discrete and networked forms were prepared and structurally characterized. Reaction of L with HgCl2 afforded a unique 1:1 (cationic/anionic) complex [Hg2(L)Cl5][Hg(L)Cl] (1). Reaction of L with Hg(CIO4)2 yielded the sandwich-type 1:2 (metal-to-ligand) complex [Hg(L)2](ClO 4)2 (2). Contrasting with the mercury(II) salts, the reactions of L with AgX (X=NO3 - and CF3SO 3 -) yielded an isostructural one-dimensional (1D) zigzag networks [Ag(L)X]n (3; X=NO3 - and 4; X=CF 3SO3 -) in which each ring of L is exo-coordinated via two S atoms and one N atom to a silver ion which is also bound to one S atom in the neighboring L such that the overall coordination geometry about each silver is four-coordinate. Whereas, reaction of L with K2PdCI4 gave a discrete exocyclic complex 5, [cisCI 2Pd(L)]. Through a successive reaction of the complex 5 with AgNO3, a heterobinuclear two-dimensional (2D) coordination polymer 6, [Pd(L)Ag2.5(NO3)4.5(H2O) 0.5]n, utilizing exocyclic Pd(II) and Ag(I) was isolated and characterized. © 2010 American Chemical Society.

Clinical experiences have suggested that East Asians show the higher risk of warfarin-related intracranial hemorrhage compared with Westerners. Therefore, different target of the International Normalized Ratio (INR) in East Asians (1.6-2.6) has been proposed and adapted in clinical practice. In terms with antiplatelet therapy, recent evidence has supported the concept of "therapeutic level of platelet reactivity" to balance clinical efficacy and safety in patients undergoing percutaneous coronary intervention (PCI) or those with acute coronary syndrome (ACS). In line with the warfarin experiences, multiple clinical and pharmacodynamic data from East Asians have shown their different therapeutic level of platelet reactivity following PCI or ACS (" East Asian Paradox"). Furthermore, like most cardiovascular drugs, P2Y12 receptor blockers have marked interethnic differences in the pharmacokinetics and pharmacodynamics. The currently performed clinical trials evaluating the clinical efficacy and safety of potent P2Y12 inhibitors mostly don't include enough number of East Asians to draw reliable conclusions. Therefore, dedicated research and guideline(s) for East Asians are required before we can apply Western recommendations for potent P2Y12 inhibitors in East Asian population. It is a time to consider the paradigm shift from "one-guideline-fits-all races"to "race-tailored antiplatelet therapy" in treating ACS patients. © Springer Science+Business Media 2014.

Park P.,Gyeongsang National University
IEEE Communications Letters | Year: 2015

The traffic generation rate of the network used for cyber-physical systems is a crucial design parameter since it directly affects the stability of physical systems and the congestion level of communication systems. In this paper, we propose a novel modeling framework of the general wireless sensor and actuator networks of cyber-physical systems where the sensor-controller and controller-actuator sides communicate over a lossy network. The performance model is then used to derive the optimal traffic generation rate of sensors and controllers for minimizing the maximum outage probability of the stability constraint of the control systems while guaranteeing a schedulability constraint. The resulting problem is a non-linear optimization problem which allows to obtain the global optimum. An efficient approximation converts the proposed optimization problem into a linear programming problem. One interesting finding is that the optimal solution assigns higher traffic generate rate on the controller-actuator link compared to the one of the sensor-controller link since the actuating-link is more critical to guarantee the stability of the control systems. © 2015 IEEE.

Park H.-D.,Joongbu University | Jun Y.-K.,Gyeongsang National University
International Journal of Software Engineering and its Applications | Year: 2013

Detecting data races is important in debugging shared memory parallel programs, because the races could exhibit unpredictable results in execution of programs. Unfortunately, previ- ous race detection techniques cannot guarantee that the detected accesses could be involved in the first races to occur in parallel programs which contain random synchronizations. This paper presents a monitoring algorithm which collects filtered key accesses of local thread blocks that are involved in races comparing with the latest filtered accesses of the other concurrent thread blocks in a particular execution of parallel programs. We discard all the accesses other than key accesses in a block to perform the race condition determination, which makes our algorithm more ecient in time and space. We alsodemonstrate the cor- rectness of our algorithm by showing at least one of the collected candidate accesses would be included in the actual first races.

Kim K.I.,Gyeongsang National University
International Journal of Software Engineering and its Applications | Year: 2013

Followed by our previous works, a study for performance evaluation of existing typical routing protocols for aircraft ad hoc networks is presented in this paper. The main objective of this evaluation is to figure out the impact of highspeed movement and spare deployment over well-known routing protocols with new mobility pattern for aircraft ad hoc networks. The chosen protocols are three major protocols according to general categorization, this is, AODV, DSDV, and GPSR.By analyzing the result of performance evaluation, we demonstrate the suitability of those in aircraft ad hoc networks in the terms of packet delivery ratio, end-to-end delay and control overhead and discuss further works in this research area. Finally, rough conclusion is made that it is necessary to develop new routing protocol based on DTN for aircraft adhoc networks.

Kim K.-I.,Gyeongsang National University
International Journal of Software Engineering and its Applications | Year: 2013

Recently aircraft ad hoc networks have received attention from many researchers since ad hoc network technology is expected to play a great role in communications between aircrafts. Due to large number of aircrafts as well as high bandwidth to meet emerging demands such as multimedia stream, ad hoc networks can be practical approach in this situation. However, since aircraft ad hoc networks possess significantly different properties to typical MANET or VANET, many research challenges remains unsolved yet. Among them, simulation study is one of key research area by providing simulation scenarios through simulator. Despite of importance, since current popular simulators do not provide the simulation environments for aircraft ad hoc networks, it is strongly required to extend the current simulators by adding several elements such as mobility model, type of node and so on. Based on above research needs, in this paper, we propose how to implementthe realistic mobility scenarios for aircraft ad hoc network. To design the relevant model, we implement new software which connects it to commercial flight simulator to generate mobility trace file. This file is converted to corresponding mobility file for each simulator. The software developed by .NET will be presented to validate its operation by diverse experiments.

Khan H.,Gyeongsang National University | Chung E.J.,Research South, Inc. | Jeon C.O.,Chung - Ang University | Chung Y.R.,Gyeongsang National University
International Journal of Systematic and Evolutionary Microbiology | Year: 2013

A Gram-staining-negative, rod-shaped, aerobic bacterial strain designated YC7003T, was isolated from a piece of rotten wood collected at Jinju, Korea. The taxonomic position of the strain was investigated using a polyphasic approach. The strain was catalase- and oxidase-positive, grew at 4-35 °C (optimum, 30 °C) and at pH 5.0-10.0 (optimum, pH 6.5-7.0). The major cellular fatty acids were C16:1ω7c and/or iso-C15:0 2-OH (summed feature 3), iso-C15:0 and C16:1ω5c and the major respiratory quinone was MK-7. The total genomic DNA G + C content was 49.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YC7003T belonged to the genus Mucilaginibacter in the family Sphingobacteriaceae with 94.4-97.2 % sequence similarities with type strains of species of the genus Mucilaginibacter. The most closely related species was Mucilaginibacter mallensis MP1X4T (97.2%). The DNA-DNA relatedness value between strain YC7003T and M. mallensis MP1X4Twas 21.7±3.3%. Based on these data, strain YC7003T represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter gynuensis sp. nov. is proposed. The type strain is YC7003T (=KACC 15532T=JCM 17705T). © 2013 IUMS.

Kim K.H.,Gyeongsang National University
International Journal of Web and Grid Services | Year: 2013

Utility-based resource management is becoming an emerging issue as the utilisation of cluster resources in Grid computing is growing rapidly. In this paper, we provide a new Imprecise Computation (IC) application model for flexible reward-based Grid resource management. An application in the proposed model consists of multiple independent jobs, in which each job has two parts: mandatory part for the minimum quality and optional part for additional computations. This application model can be applied to QoS-related Grid applications and used in adaptive resource management. We also provide scheduling algorithms for resource allocation of the IC applications based on reward. The profitable optional execution time is analysed for both space-shared and time-shared scheduling policies. Simulation results show that the proposed schemes are beneficial to both users and resource providers in terms of application acceptance rate and total reward. Copyright © 2013 Inderscience Enterprises Ltd.

Shin J.I.,Gyeongsang National University | Chung K.H.,Gyeongsang National University | Oh J.S.,International University of Korea | Lee C.W.,Hanyang University
International Journal of Information Management | Year: 2013

We performed a study to determine the influence that site quality has on repurchase intention of Internet shopping through customer satisfaction, customer trust, and customer commitment. Appropriate measures were developed and tested on 230 university students of Gyeongnam province in South Korea with a cross-sectional questionnaire survey. The results of the empirical analysis confirmed that site quality can be conceptualized as a composite of six dimensions of shopping convenience, site design, information usefulness, transaction security, payment system, and customer communication. Second, site quality positively affected customer satisfaction and customer trust, but did not affect customer commitment and repurchase intention. Third, site quality can affect repurchase intention by enhancing or attenuating customer satisfaction, customer trust, and customer commitment in online transaction situation. The mediating effect of customer satisfaction, customer trust, and customer commitment between site quality and repurchase intention is identified. Fourth, site quality indirectly affected customer commitment through customer satisfaction. Customer satisfaction indirectly affected repurchase intention through customer trust and customer commitment. Thus, it is found that site quality can be a very important factor to enhance repurchase intention in the customer perspective. © 2013 Elsevier Ltd.

Choi J.,Gyeongsang National University | Lim J.,Gyeongsang National University | Lee K.Y.,Baylor University
IEEE Transactions on Smart Grid | Year: 2013

This paper proposes a methodology for evaluating the probabilistic reliability, considering demand side management (DSM) and web based on a daily interval reliability information system for a grid constrained composite power system including wind turbine generators(WTG). The proposed model can consider capacity limitations and transmission line unavailabilities and the operation of WTG modeled by multi-states. The importance of renewable energy sources is growing at a rapid rate due to environmental concerns. A web based online daily time interval reliability integrated information system (WORRIS) is applied using the methodology proposed in this paper. This paper describes the architecture of the WORRIS Version 7.0 system. © 2012 IEEE.

Kim S.G.,Gyeongsang National University | Seo Y.G.,Gyeongsang National University
Journal of Information Processing Systems | Year: 2013

Prostate cancer is one of the most frequent cancers in men and is a major cause of mortality in the most of countries. In many diagnostic and treatment procedures for prostate disease accurate detection of prostate boundaries in transrectal ultrasound(TRUS) images is required. This is a challenging and difficult task due to weak prostate boundaries, speckle noise and the short range of gray levels. In this paper a method for automatic prostate segmentation in TRUS imagesusing Gabor feature extraction and snake-like contour is presented. This method involves preprocessing, extracting Gaborfeature, training, and prostate segmentation. The speckle reduction for preprocessing step has been achieved by using stick filter and top-hat transform has been implemented for smoothing the contour. A Gabor filter bank for extraction of rotationinvariant texture features has been implemented. A support vector machine(SVM) for training step has been used toget each feature of prostate and nonprostate. Finally, the boundary of prostate is extracted by the snake-like contouralgorithm. A number of experiments are conducted to validate this method and results showed that this new algorithm extracted the prostate boundary with less than 10.2% of the accuracy which is relative to boundary provided manually by experts. © 2013 KIPS.

Jeong B.R.,Gyeongsang National University | Sivanesan I.,Gyeongsang National University | Sivanesan I.,Konkuk University
Plant Cell, Tissue and Organ Culture | Year: 2015

Effects of plant growth regulators, light quality and sucrose on direct adventitious shoot regeneration, in vitro flowering and fruiting of Scrophularia takesimensis were investigated. The highest mean number of shoots per leaf (23.4), petiole (17.2) and stem (20.3) explants was obtained on Murashige and Skoog (MS) medium fortified with 2.0 mg l−1 BA and 1.0 mg l−1 IAA under white fluorescent light (WFL). Red light emitting diodes (LED) gave better shoot growth followed by WFL and blue LED. However, red LED treatment decreased the number of roots and induced callus at the base of shoot. The highest number of roots per shoot (9.2) and a maximum root length (8.9 cm) were obtained when the cultures were maintained under WFL. Somaclonal variation was observed when the shoot buds were cultured on the modified MS medium containing 1.0 mg l−1 IBA. The variant had variegated leaves in comparison with those of normal plantlets. The greatest frequency of flower induction (96.8 %) was obtained when the shoots were cultured on the modified MS medium containing 6.0 % (w/v) sucrose for 45 days under blue LED. The in vitro developed flowers self-fertilized and formed fruits. The culture media and environment had a positive effect on the content of phenolic compounds. Harpagoside content was high in seeds and low in shoots developed in MS medium containing BA. Among the light sources, shoots maintained under blue LED found to be best for harpagoside production (4.9 mg g−1) followed by WFL (3.3 mg g−1) and red LED (2.7 mg g−1). In vitro regenerated shoots had higher capacity to detoxify DPPH free radicals than field-grown plant samples. © 2015, Springer Science+Business Media Dordrecht.

Bukhari A.C.,Gyeongsang National University | Kim Y.-G.,Gyeongsang National University
Applied Intelligence | Year: 2013

In this article, the idea of multipurpose fuzzy semantic enhanced 3D virtual reality simulator for the evaluation of maritime robot algorithms, and for the analysis of maritime missions is presented. The simulator uses the digital mockup technology in blending with semantic domain knowledge of the system, to analyze the tasks remotely. The 3D virtual reality (VR) is proposed to help the operators provide the detailed information and guidance during real-time tele-operations, and the incorporation of fuzzy semantic knowledge makes the virtual environment intelligent and automatic. The integration of fuzzy scene independent ontology with the virtual environment (VE) engenders a knowledge driven inter operable virtual environment which eases the user in natural language querying, personalization, interpretations and manipulation. The distinctive semantic VR scene builder utility of the proposed system draws the VR environment automatically while getting the high level specification of the system for the client. The proposed simulator can be effectively used for real-time robots trainings and for the evaluation of AI based algorithms designed for intelligent vessels and AUV's without knowing the complex underlying VR scene building technologies. Furthermore, it provides the benefits to optimize the pre-process physical environment operations to mimic the real world into a virtual environment. The remote operations and feasibility analysis performed on virtual simulator can efficiently save the cost, time and claims to provide the operators a preprocessor information and guide. © 2012 Springer Science+Business Media, LLC.

Khan H.,Gyeongsang National University | Chung E.J.,Research South, Inc. | Kang D.Y.,Gyeongsang National University | Jeon C.O.,Chung - Ang University | Chung Y.R.,Gyeongsang National University
International Journal of Systematic and Evolutionary Microbiology | Year: 2013

A Gram-negative, rod-shaped, pale-orange-pigmented bacterial strain with xylan-degrading activity designated YC7004T was isolated from a rotten-wood sample collected at Jinju, Korea, and its taxonomic position was investigated by using a polyphasic approach. The strain grew optimally on R2A medium at 30 °C and at pH 6. The major isoprenoid quinone was MK7 and major fatty acids were summed feature 3, iso-C15:0, C16:0, iso-C17:0 3-OH, iso-C17:1 ω9c and C16:1 ω5c. The G+C content of the genomic DNA was 40.0 mol%. Phylogenetic analysis based on the 16S rRNA gene sequences showed that the strain belongs to the genus Mucilaginibacter in the family Sphingobacteriaceae. The most closely related species were Mucilaginibacter daejeonensis (95.5%), Mucilaginibacter frigoritolerans (94.6%) and Mucilaginibacter mallensis (94.0%). Based on the phylogenetic and chemotaxonomic data analyses, strain YC7004T represents a novel species of the genus Mucilaginibacter with the proposed name of Mucilaginibacter jinjuensis sp. nov. The type strain is YC7004T (=KACC 16571T=NBRC 108856T). © 2013 IUMS Printed in Great Britain.

Azadi Kenary H.,Yasouj University | Je Cho Y.,Gyeongsang National University
Computers and Mathematics with Applications | Year: 2011

In this paper, we prove the generalized HyersUlam stability of the following mixed additivequadratic functional equation: 2f(x+y2)+f(x-y2)+f(y-x2)= f(x)+f(y) in various spaces. © 2011 Elsevier Ltd. All rights reserved.

Lee S.-I.,University of California at San Diego | Lee S.-I.,Gyeongsang National University | Boyle D.L.,University of California at San Diego | Berdeja A.,Isis Pharmaceuticals | Firestein G.S.,University of California at San Diego
Arthritis Research and Therapy | Year: 2012

Introduction: The c-Jun N-terminal kinase (JNK) is a key regulator of matrix metalloproteinase (MMP) and cytokine production in rheumatoid arthritis (RA) and JNK deficiency markedly protects mice in animal models of arthritis. Cytokine-induced JNK activation is strictly dependent on the mitogen-activated protein kinase kinase 7 (MKK7) in fibroblast-like synoviocytes (FLS). Therefore, we evaluated whether targeting MKK7 using anti-sense oligonucleotides (ASO) would decrease JNK activation and severity in K/BxN serum transfer arthritis.Methods: Three 2'-O-methoxyethyl chimeric ASOs for MKK7 and control ASO were injected intravenously in normal C57BL/6 mice. PBS, control ASO or MKK7 ASO was injected from Day -8 to Day 10 in the passive K/BxN model. Ankle histology was evaluated using a semi-quantitative scoring system. Expression of MKK7 and JNK pathways was evaluated by quantitative PCR and Western blot analysis.Results: MKK7 ASO decreased MKK7 mRNA and protein levels in ankles by about 40% in normal mice within three days. There was no effect of control ASO on MKK7 expression and MKK7 ASO did not affect MKK3, MKK4 or MKK6. Mice injected with MKK7 ASO had significantly less severe arthritis compared with control ASO (P < 0.01). Histologic evidence of synovial inflammation, bone erosion and cartilage damage was reduced in MKK7 ASO-treated mice (P < 0.01). MKK7 deficiency decreased phospho-JNK and phospho-c-Jun in ankle extracts (P < 0.05), but not phospho-MKK4. Interleukin-1beta (IL-1β), MMP3 and MMP13 gene expression in ankle joints were decreased by MKK7 ASO (P < 0.01).Conclusions: MKK7 plays a critical regulatory role in the JNK pathway in a murine model of arthritis. Targeting MKK7 rather than JNK could provide site and event specificity when treating synovitis. © 2012 Lee et al.; licensee BioMed Central Ltd.

Eshaghi Gordji M.,Semnan University | Baghani H.,Semnan University | Cho Y.J.,Gyeongsang National University
Mathematical and Computer Modelling | Year: 2011

Following the definition of coupled fixed point [T. G. Bhaskar, V. Lakshmikantham, Fixed point theorems in partially ordered metric spaces and applications, Nonlinear Anal. 65 (2006) 1379-1393], we prove a coupled fixed point theorem for contractive mappings in partially complete intuitionistic fuzzy normed spaces. © 2011 Elsevier Ltd.

Meganathan C.,Gyeongsang National University | Sebastian S.,Annamalai University | Kurt M.,Ahi Evran Oniversitesi Fen Edebiyat Fakoltesi Fizik Bolomo | Lee K.W.,Gyeongsang National University | Sundaraganesan N.,Annamalai University
Journal of Raman Spectroscopy | Year: 2010

Vibrational spectral analysis was carried out for 4-methoxy-2-methyl benzoic acid (4M2MBA) by using Fourier transform infrared (FT-IR) (solid, gas phase) and FT-Raman spectroscopy in the range of 400-4000 and 10-3500 cm -1 respectively. The effects of molecular association through O-H···O hydrogen bonding have been described by the single dimer structure. The theoretical computational density functional theory (DFT) and Hatree-Fock (HF) method were performed at 6-311++G(d,p) levels to derive the equilibrium geometry, vibrational wavenumbers, infrared intensities and Raman scattering activities. The scaled theoretical wavenumbers were also shown to be in good agreement with experimental data. The first-order hyperpolarizability (β0) of this novel molecular system and related properties (β, α0 and Δα of 4M2MBA are calculated using the B3LYP/cc-pvdz basis set, based on the finite-field approach. A detailed interpretation of the infrared and Raman spectra of 4M2MBA is reported. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule were also constructed and compared with the experimental one. Copyright © 2010 John Wiley & Sons, Ltd.

Kim S.H.,Korea Research Institute of Bioscience and Biotechnology | Ahn Y.O.,Korea Research Institute of Bioscience and Biotechnology | Ahn M.-J.,Gyeongsang National University | Lee H.-S.,Korea Research Institute of Bioscience and Biotechnology | Kwak S.-S.,Korea Research Institute of Bioscience and Biotechnology
Phytochemistry | Year: 2012

Sweetpotato (Ipomoea batatas Lam.) is an important industrial crop and source of food that contains useful components, including antioxidants such as carotenoids. β-Carotene hydroxylase (CHY-β) is a key regulatory enzyme in the beta-beta-branch of carotenoid biosynthesis and it catalyzes hydroxylation into both β-carotene to β-cryptoxanthin and β-cryptoxanthin to zeaxanthin. To increase the β-carotene content of sweetpotato through the inhibition of further hydroxylation of β-carotene, the effects of silencing CHY-β in the carotenoid biosynthetic pathway were evaluated. A partial cDNA encoding CHY-β was cloned from the storage roots of orange-fleshed sweetpotato (cv. Shinhwangmi) to generate an RNA interference-IbCHY-β construct. This construct was introduced into cultured cells of white-fleshed sweetpotato (cv. Yulmi). Reverse transcription- polymerase chain reaction analysis confirmed the successful suppression of IbCHY-β gene expression in transgenic cultured cells. The expression level of phytoene synthase and lycopene β-cyclase increased, whereas the expression of other genes showed no detectable change. Down-regulation of IbCHY-β gene expression changed the composition and levels of carotenoids between non-transgenic (NT) and transgenic cells. In transgenic line #7, the total carotenoid content reached a maximum of 117 μg/g dry weight, of which β-carotene measured 34.43 μg/g dry weight. In addition, IbCHY-β-silenced calli showed elevated β-cryptoxanthin and zeaxanthin contents as well as high transcript level P450 gene. The 2,2-diphenyl-1- picrylhydrazyl radical scavenging activity (DPPH) in transgenic cells was more than twice that in NT cells. RNA-IbCHY-β calli increased abscisic acid (ABA) content, which was accompanied by enhanced tolerance to salt stress. In addition, the production of reactive oxygen species measured by 3,3′-diaminobenzidine (DAB) staining was significantly decreased in transgenic cultured cells under salt stress. Taken together, the present results indicate that down-regulation of IbCHY-β increased β-carotene contents and total carotenoids in transgenic plant cells and enhanced their antioxidant capacity. © 2011 Elsevier Ltd. All rights reserved.

Paek S.-M.,Gyeongsang National University
Molecules | Year: 2015

Synthetic approaches to macrosphelide derivatives, based on medicinal chemistry, are summarized. This review contains conventional medicinal chemistry approaches, combinatorial chemistry, fluorous tagging techniques and affinity chromatography preparation. In addition, advances in their apoptosis-inducing activities are also included. © 2015 by the authors; licensee MDPI.

Kim D.J.,Gyeongsang National University | Jo M.J.,Gyeongsang National University | Nam S.Y.,Gyeongsang National University
Journal of Industrial and Engineering Chemistry | Year: 2015

Proton exchange membrane fuel cells (PEMFCs) represent a promising means for the generation of power in the 21st century because of their high efficiency compared to the coal combustion engine and eco-environment. Among various components found in the fuel cell systems, proton exchange membranes (PEMs) are pivotal. Currently, the polymer electrolyte membrane fuel cells are based on perfluoro sulfonic acid membranes such as Nafion, and Flemion, which have certain drawbacks such as high fuel crossover and cost. Consequently, researchers have focused on making PEMs with high proton conductivity, durability, thermal stability, maximum power density and low fuel crossover, and low cost. In the recent years, the hybrid organic-inorganic composite membrane has emerged as an interesting alternative. It provides a unique combination of organic and inorganic properties, and overcomes the limitations of the pure polymeric membranes. In this paper, we have reviewed several alternatives for the fabrication and evaluation of polymer electrolyte and composite membranes for fuel cell applications. © 2014 The Korean Society of Industrial and Engineering Chemistry.

This study proposes a product data management (PDM) database that can support engineering change analysis (ECA). It can integrate ECA with the existing main product development process managed by PDM systems. Since engineering change (EC) history is a key EC data element that enables ECA, this study extends PDM databases to represent the EC history with existing entities for ECs and associated products and their product structures. To show the feasibility of the proposed PDM database, this study integrates a prototype PDM system with on-line analytical processing (OLAP) tools and a data mining module for ECA. It also applies the implemented tools to two typical ECA applications, EC evaluation and EC propagation problems. The illustrative application examples show that the proposed PDM database can support ECA through multidimensional data analysis with OLAP and data mining with association rules. © 2015 Elsevier B.V. All rights reserved.

Lee T.,Gyeongsang National University | Modarres R.,INRS ETE | Ouarda T.B.M.J.,INRS ETE | Ouarda T.B.M.J.,Masdar Institute of Science and Technology
Hydrological Processes | Year: 2013

In recent decades, copula functions have been applied in bivariate drought duration and severity frequency analysis. Among several potential copulas, Clayton has been mostly used in drought analysis. In this research, we studied the influence of the tail shape of various copula functions (i.e. Gumbel, Frank, Clayton and Gaussian) on drought bivariate frequency analysis. The appropriateness of Clayton copula for the characterization of drought characteristics is also investigated. Drought data are extracted from standardized precipitation index time series for four stations in Canada (La Tuque and Grande Prairie) and Iran (Anzali and Zahedan). Both duration and severity data sets are positively skewed. Different marginal distributions were first fitted to drought duration and severity data. The gamma and exponential distributions were selected for drought duration and severity, respectively, according to the positive skewness and Kolmogorov-Smirnov test. The results of copula modelling show that the Clayton copula function is not an appropriate choice for the used data sets in the current study and does not give more drought risk information than an independent model for which the duration and severity dependence is not significant. The reason is that the dependence of two variables in the upper tail of Clayton copula is very weak and similar to the independent case, whereas the observed data in the transformed domain of cumulative density function show high association in the upper tail. Instead, the Frank and Gumbel copula functions show better performance than Clayton function for drought bivariate frequency analysis. © 2012 John Wiley & Sons, Ltd.

Yoon Y.-S.,Gyeongsang National University | Ha H.-Y.,Korea Institute of Materials Science | Lee T.-H.,Korea Institute of Materials Science | Kim S.,Gyeongsang National University
Corrosion Science | Year: 2014

Stress corrosion cracking (SCC) susceptibility of austenitic Fe18Cr10Mn alloys with 0.3N, 0.6N and 0.3N0.3C was investigated in aqueous chloride environment using a slow strain rate test method. The SCC susceptibility of Fe18Cr10Mn alloys in 2. M NaCl solution at 50. °C under constant anodic potential condition decreased with increase in N content from 0.3 to 0.6. wt%, and with addition of 0.3. wt% C to the Fe18Cr10Mn0.3N alloys. The present study strongly suggested that the beneficial effects of N and C on the SCC behavior of Fe18Cr10Mn alloys would be associated with the resistance to pitting corrosion initiation and the repassivation kinetics. © 2013 Elsevier Ltd.

Chung D.S.,Chung - Ang University | Kim Y.-H.,Gyeongsang National University | Lee J.-S.,Daegu Gyeongbuk Institute of Science and Technology
Nanotechnology | Year: 2014

We demonstrate an approach to enhance the photosensitivity of an organic single-crystal photodetector by combining it with a nanocrystal (NC) array. A systematic study of the dependence of the photodetector performance on illumination wavelength and light power together with the charge carrier mobility reveals that charge separation at the single-crystal/CdSe NC interface and subsequent electron trapping in the CdSe NCs generates effective photoconductive gain by hole circulation through the high-mobility single crystal. As a result, the responsivity and specific detectivity reached values up to 50 A W-1 and 2 × 109 cm Hz1/2 W-1, respectively. © 2014 IOP Publishing Ltd.

Murale D.P.,Korea Advanced Institute of Science and Technology | Kim H.,Gyeongsang National University | Choi W.S.,Gyeongsang National University | Churchill D.G.,Korea Advanced Institute of Science and Technology
RSC Advances | Year: 2014

A chloropropionate-caged fluorescein probe allows for prompt detection of cysteine over other biothiols, e.g., homocysteine with a limit of detection of 12.8 μM. © 2014 The Royal Society of Chemistry.

Seo J.H.,Gyeongsang National University
The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi | Year: 2013

Duodenal ulcers occur relatively frequently in adolescents, like in adults, and may relate to Helicobacter pylori infection and duodenal gastric metaplasia (DGM). This study investigated the association between H. pylori infection and DGM in healthy adults aged 20-29. Between 1995 and 2005, endoscopic biopsies of the duodenum, antrum and body were taken from healthy, young volunteers, who were first-year medical students, faculty staff, residents, and research assistants of Gyeongsang National University in Jinju, Korea. Urease tests were performed and the extent of DGM and histopathological grades according to the Updated Sydney System were determined. In total, 662 subjects were enrolled (429 males and 233 females). The median age was 22.3 years. The overall incidence of DGM was 11.5% but DGM was more frequent in males (15.4%) than in females (4.3%) (p<0.0001). While H. pylori positivity rates changed significantly during the 1995-2005 period (p<0.01), the incidences of DGM did not. DGM was observed in 7.2% and 14.9% of subjects who were and were not colonized with H. pylori, respectively. DGM was also associated with less severe chronic gastritis and the absence of active gastritis in both the antrum and body, and the absence of follicles in the antrum (p<0.05). These findings suggested that DGM is not rare in healthy young adults and is unrelated to gastric H. pylori infection.

Sohn W.-M.,Gyeongsang National University | Na B.-K.,Gyeongsang National University | Yoo J.M.,Gyeongsang National University
Korean Journal of Parasitology | Year: 2011

The present study was performed to describe 2 cases of human thelaziasis (HT) which occurred in Gyeongsangnam-do and to briefly review the previously reported Korean cases. A 58-year old woman, residing in Hadong-gun, Gyeongsangnam-do, came to Gyeongsang National University Hospital (GNUH) complaining of foreign body sensation and itching of the right eye in March 2000. Total 6 adult nematodes of Thelazia callipaeda (2 males and 4 females) were detected in her right eye. A 80-year old man, residing in Jinju-si, Gyeongsangnam-do, came to GNUH complaining of foreign body sensation, itching, and pain of the right eye in December 2007. A total of 5 worms (4 females and 1 degenerated) were removed from his right eye. We analyzed characteristics of the total 39 Korean HT cases reported to date, including the present 2 cases. Most of the cases (71.8%) occurred in Seoul and Gyeonggi-do before 2000, and 21 cases (53.8%) were males and 18 (46.2%) were females. The prevalence was higher in younger ages below 30 years (48.7%) than 31-60 years (41.0%) and over 61 years (10.3%). The seasonal prevalence showed a higher incidence in autumn (43.6%) than in other seasons. Most of the cases (94.9%) were conjunctival sac infections and only 2 (5.1%) were intraocular cases. The present 2 HT cases are the first reported cases in Gyeongsangnam-do. Some characteristics of Korean HT cases were analyzed. © 2011, Korean Society for Parasitology.

Han X.,Gyeongsang National University | Kumar D.,Gyeongsang National University | Chen H.,Gyeongsang National University | Wu S.,Gyeongsang National University | Kim J.-Y.,Gyeongsang National University
Journal of Experimental Botany | Year: 2014

Plant cells utilize mobile transcription factors to transmit intercellular signals when they perceive environmental stimuli or initiate developmental programmes. Studies on these novel cell-to-cell signals have accumulated multiple pieces of evidence showing that non-cell-autonomous transcription factors play pivotal roles in most processes related to the formation and development of plant organs. Recent studies have explored the evolution of mobile transcription factors and proposed mechanisms for their trafficking through plasmodesmata, where a selective system exists to facilitate this process. Mobile transcription factors contribute to the diversity of the intercellular signalling network, which is also established by peptides, hormones, and RNAs. Crosstalk between mobile transcription factors and other intercellular molecules leads to the development of complex biological signalling networks in plants. The regulation of plasmodesmata appears to have been another major step in controlling the intercellular trafficking of transcription factors based on studies of many plasmodesmal components. Furthermore, diverse omics approaches are being successfully applied to explore a large number of candidate transcription factors as mobile signals in plants. Here, we review these fascinating discoveries to integrate current knowledge of non-cell-autonomous transcription factors. © 2013 The Author.

Park M.G.,Yeson Rehabilitation Medicine Hospital | Ha Y.,Gyeongsang National University
Journal of Korean Academy of Nursing | Year: 2014

Purpose: This study was conducted to develop a self-management program using goal setting for patients after a stroke. The program was based on a theory-based Goal setting and Action Planning framework (G-AP), and the effectiveness of the program was examined. Methods: A non-equivalent control group pretest-posttest design was used. The experimental group (n=30) received the self-management program using goal setting based on the G-AP over 7 weeks. The education was delivered individually with a specifically designed stroke workbook. The control group (n=30) received only patient information leaflets about stroke. Results: There were significant differences between the two groups. Stroke knowledge, self-efficacy, and health behavior compliance were significantly higher (all p<.001), and hospital anxiety (p<.001) and depression (p<.001) were significantly lower in the experimental group compared to the control group. Conclusion: This self-management program using goal setting based on a G-AP was found to be useful and beneficial for patients in stroke rehabilitation settings. © 2014 Korean Society of Nursing Science.

Background: Ferulic acid provides a neuroprotective effect during cerebral ischemia through its anti-oxidant function. Protein phosphatase 2A (PP2A) is a serine and threonine phosphatase that contributes broadly to normal brain function. This study investigated whether ferulic acid regulates PP2A subunit B in a middle cerebral artery occlusion (MCAO) animal model and glutamate toxicity-induced neuronal cell death. Methodology/Principal Findings: MCAO was surgically induced to yield permanent cerebral ischemic injury in rats. The rats were treated with either vehicle or ferulic acid (100 mg/kg, i.v.) immediately after MCAO, and cerebral cortex tissues were collected 24 h after MCAO. A proteomics approach, RT-PCR, and Western blot analyses performed to identification of PP2A subunit B expression levels. Ferulic acid significantly reduced the MCAO-induced infarct volume of the cerebral cortex. A proteomics approach elucidated the reduction of PP2A subunit B in MCAO-induced animals, and ferulic acid treatment prevented the injury-induced reduction in PP2A subunit B levels. RT-PCR and Western blot analyses also showed that ferulic acid treatment attenuates the injury-induced decrease in PP2A subunit B levels. Moreover, the number of PP2A subunit B-positive cells was reduced in MCAO-induced animals, and ferulic acid prevented these decreases. In cultured neuronal cells, ferulic acid treatment protected cells against glutamate toxicity and prevented the glutamate-induced decrease in PP2A subunit B. Conclusions/Significance: These results suggest that the maintenance of PP2A subunit B by ferulic acid in ischemic brain injury plays an important role for the neuroprotective function of ferulic acid. © 2013 Phil-Ok Koh.

Cho Y.J.,Gyeongsang National University | Argyros I.K.,Cameron University | Petrot N.,Naresuan University
Computers and Mathematics with Applications | Year: 2010

In this paper, we introduce an iterative method for finding a common element of the set of solutions of the generalized equilibrium problems, the set of solutions for the systems of nonlinear variational inequalities problems and the set of fixed points of nonexpansive mappings in Hilbert spaces. Furthermore, we apply our main result to the set of fixed points of an infinite family of strict pseudo-contraction mappings. The results obtained in this paper are viewed as a refinement and improvement of the previously known results. © 2010 Elsevier Ltd. All rights reserved.

Joo S.T.,Gyeongsang National University | Kim G.D.,Jeju National University | Hwang Y.H.,Gyeongsang National University | Ryu Y.C.,Jeju National University
Meat Science | Year: 2013

Variations of fresh meat quality exist because the quality traits are affected by various intrinsic and extrinsic factors. Because the meat quality is basically dependent on muscle fiber characteristics, numerous studies have reported the relationship between quality traits and fiber characteristics. Despite intensive research, the relationship is yet to be fully established, however, the present knowledge suggests several potential ways to manipulate muscle fiber characteristics to improve meat quality. The present paper reviews the definition of fresh meat quality, meat quality traits and variations of meat quality. Also, this review presents recent knowledge underlying the relationship between fresh meat quality traits and muscle fiber characteristics. Finally, the present work proposes several potential factors including breed, genotype, sex, hormone, growth performance, diet, muscle location, exercise and ambient temperature that can be used to manipulate muscle fiber characteristics and subsequently meat quality in animals. © 2013 The Authors.

Lee S.,Gyeongsang National University | Ahn A.,Gyeongsang National University | Choi M.Y.,Gyeongsang National University
Physical Chemistry Chemical Physics | Year: 2012

An Al metal plate was ablated by a pulsed Nd-YAG laser to produce nano-structured Al and gamma-Al 2O 3 in deionized water without any surfactants or catalysts. In this study, direct evidence for the production of Al 3+ ions from the plasma plume is presented for the first time by characterizing the absorption and emission spectra of their [Al(salophen)] + complex. Very interestingly, a remarkable increase in the fluorescence intensity was observed when the Al 3+ ions, produced via the pulsed laser ablation, complexed with the salophen ligand. This fluorescence 'turn-on' behaviour of [Al(salophen)] + was investigated by DFT/TD-DFT calculations. Based on these results, mechanisms for the production of aluminium and alumina nanoparticles in the pulsed laser ablation in liquid (PLAL) process are proposed. © 2012 the Owner Societies.

Han N.S.,Kyung Hee University | Shim H.S.,Kyung Hee University | Lee S.,Gyeongsang National University | Park S.M.,Kyung Hee University | And 2 more authors.
Physical Chemistry Chemical Physics | Year: 2012

The optical properties of single zinc oxide (ZnO) nanolasers are investigated. ZnO nanowires with different diameters and lengths are prepared by chemical vapor transport. The diameter plays an important role in the stimulated emission process in nanowires. The spectral shift and spacing of Fabry-Pérot-type modes imply a strong light-matter interaction in the lasing nanowires, which is explained by the exciton-polariton model. The polarization of the electric field in the lasing nanowires is perpendicular to the long axis of the nanowire and parallel to the substrate plane. The coexistence of the transverse modes is distinguished by decomposing the peak shape and the degree of polarization. In addition to the transverse mode of the lasing with the polarization parallel to the substrate plane, the lasing mode with the polarization perpendicular to the substrate plane is observed. © 2012 the Owner Societies.

Kim K.H.,Yonsei University | Kim J.Y.,Yonsei University | Kim M.O.,Gyeongsang National University | Moon M.H.,Yonsei University
Journal of Proteomics | Year: 2012

This study demonstrates the use of on-line isoelectric focusing/asymmetrical flow field-flow fractionation (IEF-AF4), a non-gel based high speed two dimensional (isoelectric point and hydrodynamic diameter) protein separation device used for the isolation/separation of phosphoproteins. IEF-AF4 performance was evaluated by first fractionating α-casein molecules at different pIs and sizes. Collected proteins were analyzed by nanoflow liquid chromatography-tandem mass spectrometry (nLC-MS n) to determine various isoforms of the phosphopeptides as well as the relative ratio of phosphorylated and unmodified peptides. A narrow pH cut (δpH=0.5) of carrier ampholyte was used in IEF-AF4 to finely resolve phosphoproteins by pI. When the channel lane of multilane AF4 became acidic, the relative ratio of phosphorylated to unmodified or less phosphorylated peptides increased. The current method was applied to prostate cancer cell lysates to demonstrate that IEF-AF4 can examine the relative abundances of specific phosphoproteins, known as biomarkers, in prostate cancer. While affinity-based enrichment methods remove unmodified peptides, IEF-AF4 offers intact phosphoprotein separation at the protein level without removing unmodified proteins. IEF-AF4 enables quantitative analysis without isotope labeling. © 2012 Elsevier B.V.

Shin D.-Y.,University of Ulsan | Chung J.,University of Ulsan | Joe Y.,University of Ulsan | Pae H.-O.,Wonkwang University | And 4 more authors.
Blood | Year: 2012

The circulating peptide hormone hepcidin maintains systemic iron homeostasis. Hepcidin production increases duringinflammation and as a result of endoplasmic reticulum (ER) stress. Elevatedhepcidin levels decrease dietary iron absorption and promote iron sequestration in reticuloendothelial macrophages. Furthermore, increased plasma hepcidin levels cause hypoferremia and the anemia associated with chronic diseases.The signal transduction pathways that regulate hepcidin during inflammationand ER stress include the IL-6- dependent STAT-3 pathway and the unfolded protein response-associated cyclic AMP response element-binding protein-H (CREBH) pathway, respectively. We show that carbon monoxide (CO) suppresses hepcidin expression elicited by IL-6- and ER-stress agents by inhibiting STAT-3 phosphorylation and CREBH maturation, respectively. The inhibitory effect of CO on IL-6-inducible hepcidin expression is dependent on the suppressor of cytokine signaling-3 (SOCS-3) protein. Induction of ER stress in mice resulted in increased hepatic and serum hepcidin. CO administration inhibited ER-stress-induced hepcidin expression in vivo. Furthermore, ER stress caused iron accumulation in splenic macrophages, which could be prevented by CO. Our findings suggest novel anti-inflammatory therapeutic applications for CO, as well as therapeutic targets for the amelioration of anemia in the hypoferremic condition associated with chronic inflammatory and metabolic diseases. © 2012 by The American Society of Hematology.

Liu Y.,Ewha Womans University | Jun E.J.,Ewha Womans University | Kim G.,Ewha Womans University | Lee A.-R.,Gyeongsang National University | And 2 more authors.
Chemical Communications | Year: 2014

A novel bispyrene compound was synthesized to selectively detect RNA through excimer emission "turn-on" in aqueous solution at physiological pH (7.4). The compound was used to successfully image RNA in HeLa cells. © 2014 The Royal Society of Chemistry.

Okoloko I.,Cape Peninsula University of Technology | Kim Y.,Gyeongsang National University
Systems and Control Letters | Year: 2014

In this paper, we consider a team of spacecraft which requires changing its orientation to a common attitude using a decentralized control scheme under a connected communication topology, while satisfying cone avoidance constraints due to blind celestial objects, plume impingement and so on. For this purpose, we first combine consensus theory and optimization theory to develop a quaternion-based attitude consensus protocol. Based on the communication graph at each time step, each spacecraft generates a guidance command or reference attitude trajectory by synthesizing a series of Laplacian-like matrix P(t), using semidefinite programming (SDP) which involves linear matrix inequalities (LMIs). It is analytically shown that this series of matrices P(t) is capable of collectively driving the initial attitudes to a common consensus attitude. For satisfying cone avoidance constraints, exclusion zones are then identified and expressed as LMIs. This identification of the exclusion zones gives rise to selecting safe waypoints from the reference attitude trajectory and then to passing through the selected waypoints while avoiding the exclusion zones via proper control inputs. This solution procedure is demonstrated via numerical simulations of coordinated attitude rendezvous and attitude formation acquisition of multiple spacecraft with cone avoidance manoeuvres. © 2014 Elsevier B.V. All rights reserved.

Chen Z.,Wuhan University | Kang S.G.,Gyeongsang National University
International Journal of Distributed Sensor Networks | Year: 2014

A three-dimensional (3D) orthogonal frequency division multiplexing (OFDM) system with peak-to-average power ratio (PAPR) reduction method for the wireless sensor networks (WSNs) is presented. The transmit power of wireless nodes in an ad hoc network is strictly limited. Thus, high PAPR of the 3D OFDM system is a possible drawback when it is considered as a physical layer transmission scheme for the WSNs. Here, we propose an improved partial transmit sequence (PTS) technique to reduce PAPR of the OFDM system with 3D modulation formats. In the proposed algorithm, the components of 3D signals are assigned to different subblocks using a diagonal rule (DR), increasing randomness of the signals in the disjoint subblocks forcibly. As a result, the proposed method reduces PAPR of the 3D OFDM system significantly without increase in computational complexity. Hence, the proposed algorithm makes the 3D OFDM system be a possible candidate for a physical layer transmission scheme in future WSNs. © 2014 Zhenxing Chen and Seog Geun Kang.

Shah B.,Gyeongsang National University | Kim K.-I.,Gyeongsang National University
International Journal of Distributed Sensor Networks | Year: 2014

Real-time applications are time and event critical, therefore they have strict constraint on delay, packet loss, and energy consumption in many wireless sensor networks (WSNs) scenarios, which demands the network to continue QoS operations for a preconfigured lifetime. Due to the scarce energy constraint sensor nodes in WSNs, guaranteed network lifetime is more desirable than unpredictable and uncertain prolonged lifetime. However, in spite of its importance and necessity in WSNs real-time deployment, no research work has been proposed to solve this complex problem. In this paper, we present a new centralized energy and coverage aware node scheduling scheme for WSNs to analyze energy usage as well as balancing energy consumption among nodes to survive for the preconfigured lifetime. Furthermore, the scheduling algorithm is extended to provide real-time routing by adjusting dynamic transmission range according to current energy state of a sensor node. Thus, the energy and coverage aware scheduling with dynamic range forwarding enables the unreliable WSNs to accomplish real-time routing for a guaranteed network lifetime. Simulation results show that the proposed scheme can achieve a 10% increase in real-time packets meeting their deadline and a significantly longer guaranteed network lifetime than protocols reported in the literature. © 2014 Babar Shah and Ki-Il Kim.

Li B.,Gyeongsang National University | Kim K.-I.,Gyeongsang National University
Wireless Networks | Year: 2014

The multimedia transmission based real-time applications have posed a big challenge to wireless sensor networks (WSNs) where both reliability and timeliness need to be guaranteed at the same time, to support an acceptable Quality of Service (QoS). The existing real-time routing protocols, however, are not able to meet the QoS requirements of realtime applications because of the inherent resource constraint of sensor nodes and instability of wireless communication. Therefore, we propose a real-time scheme in this paper, including a QoS-aware routing protocol and a set of fault recovery mechanisms, for (m,k)-firm based real-time applications over WSNs. A local status indicator which is specially devised for (m,k)-firm stream, is used for intermediate nodes to monitor and evaluate their local conditions. The proposed routing protocol takes into account of packet deadline, node condition and remaining energy of next hop, to make optimal forwarding decision. Additionally, according to the stream QoS and node condition, the proposed fault recovery mechanisms are utilized for nodes to handle the congestion, link failure and void problems occurred during transmission and remain the desired reliability and timeliness requirements. The proposed scheme has been well studied and verified through simulations. The results have proved the efficiency of the proposed scheme in terms of high successful transmission ratio, small end-to-end delay and long lifetime of network. © 2013 Springer Science+Business Media New York.

Bagchi S.,Gyeongsang National University
Computers and Electrical Engineering | Year: 2014

Scheduling and execution of remote processes are integral parts of designing grid and cloud computing systems, which aim to utilize the idle CPU and memory resources of a node. However, such execution tends to degrade the overall performance of a node through over-loading and delaying the execution of local processes. This paper proposes the Admission Control and Scheduling (ACS) algorithm for execution of remote processes in a node based on online estimation method. The experimental results illustrate that the algorithm successfully schedules a large set of CPU-bound and IO-bound remote processes without degrading overall performance of a node. The comparisons of CPU-utilization and memory-utilization of an idle node and a stable node executing remote processes show that, the average utilizations are enhanced by 26.65% and 24.5%, respectively. However, the ACS algorithm successfully maintains the load-balance in a node so that, the performance of the local processes remains unaffected. © 2013 Elsevier Ltd. All rights reserved.

Shah B.,Gyeongsang National University | Kim K.-I.,Gyeongsang National University
Wireless Personal Communications | Year: 2014

With the rapid growth of individual mobile devices, the researchers are facing new challenges to deploy unstructured peer-to-peer (P2P) applications over mobile ad hoc networks (MANETs)Empirical studies indicates that although P2P and MANETs have similar preferences, but the resultant networks are not performing efficient and effective searching due to peer discovery, connectivity and mobility problemsTo resolve these issues, the existing techniques mostly rely on flooding and random walks in P2P over MANETs to discover object of interest and thus introduce incredible network trafficThus, this article proposes Gnutella like unstructured P2P network to better meets the mobility requirement of ad hoc networks to optimize search performanceThe proposed system presents a novel cache optimization technique and enhances ultrapeer selection scheme to make communication more efficient between peers and ultrapeerFurthermore for quick and efficient search, we explore a novel jumping multiple walkers random walk approach with controlled replicationThe proposed search mechanism not only reduces the effective query search time but also remarkably reduce network overheadWe validate our analysis and compare our proposal to competing protocols in simulationsSimulation results show that proposed scheme gives better performance than the competing protocols in terms of (1) the successful ratio of resolving a query, (2) the time and hop count of routing a query message, (3) the message overhead, and (4) average message response time. © 2013 Springer Science+Business Media New York.

Lee W.,Gyeongsang National University | Cho D.-H.,Korea Advanced Institute of Science and Technology
IEEE Transactions on Wireless Communications | Year: 2014

We compare the capacity of two most popular methods for acquiring the state of the spectrum in cognitive radio technology: geolocation-database-based schemes and spectrum-sensing-based schemes. For the comparison, we use a new Hidden Markov Chain based channel model, because recent measurements show that a conventional two-state model, which has been widely used, is not appropriate for modeling the behavior of channels in the cognitive environment. We also consider more generic cognitive environments in which each wireless system has its own licensed bands and uses unlicensed bands in addition to its licensed bands to increase its capacity. This type of wireless systems can comprise conventional cognitive radio systems by letting the number of licensed bands be zero. Moreover, we have derived the optimal number of unlicensed bands to be used for maximizing the capacity of wireless system by taking into account interference from neighboring wireless systems. Through simulations, we compare the capacity of wireless systems with two channel state acquisition schemes and show the counterbalancing relation between two schemes, which has never been investigated in previous works. To the best of our knowledge, this is the first work to compare the capacity of these two schemes for acquiring the state of the spectrum. © 2002-2012 IEEE.

Jeong B.G.,Pusan National University | Kim B.C.,Pusan National University | Moon Y.H.,Gyeongsang National University | Eom I.K.,Pusan National University
Signal Processing | Year: 2014

In this paper, we present a noise parameter estimation method using a simplified signal-dependent noise model. The generic Poisson-Gaussian noise model is simplified to a Gaussian-Gaussian noise model. From the simplified noise model, we experimentally verify that the value obtained by the robust median estimator is almost the same as the mean of the noise standard deviation. Based on this property, the noise model parameters are estimated by the least square method. Simulation results show that the estimation performance using our proposed algorithm is compatible with the performance of the existing method. Our method can generate good parameter estimation results with reduced computational complexity. © 2013 Elsevier B.V.

Ban T.-W.,Gyeongsang National University
IEICE Transactions on Communications | Year: 2014

Recently, small cell systems such as femto cell are being considered as a good alternative that can support the increasing demand for mobile data traffic because they can significantly enhance network capacity by increasing spatial reuse. In this paper, we analyze the coverage and capacity of a femto cell when it is deployed in a hotspot to reduce the traffic loads of neighboring macro base stations (BSs). Our analysis results show that the coverage and capacity of femto cell are seriously affected by surrounding signal environment and they can be greatly enhanced by adapting power allocation for channels to the surrounding environment. Thus, we propose an adaptive power partitioning scheme where power allocation for channels can be dynamically adjusted to suit the environment surrounding the femto cell. In addition, we numerically derive the optimal power allocation ratio for channels to optimize the performance of the femto cell in the proposed scheme. It is shown that the proposed scheme with the optimal channel power allocation significantly outperforms the conventional scheme with fixed power allocation for channels. © 2014 The Institute of Electronics, Information and Communication Engineers.

Lee S.,Gyeongsang National University | Kwon H.,Gyeongsang National University | Jeong K.,Gyeongsang National University | Pak Y.,Gyeongsang National University
International Journal of Oncology | Year: 2011

We investigated whether altering caveolin-2 (cav-2) expression affects the proliferation of cancer cells. Cav-2 was not detected in HepG2, SH-SY5Y and LN-CaP cells, and the loss of cav-2 expression was not restored by 5-aza-2′-deoxycytidine treatment. In contrast, C6, HeLa, A549, MCF7 and PC3M cells expressed cav-2. Effects of re-expression of exogenous cav-2 in HepG2, SH-SY5Y and LN-CaP cells, and siRNA-mediated down-regulation of endogenous cav-2 in C6, HeLa, A549, MCF7 and PC3M cells on cancer proliferation were examined by MTT assay, colony formation assay and flow cytometric analysis. Cav-2 transfection in HepG2 hepatocellular carcinoma cells and knockdown in C6 glioma cells caused reduction in cell proliferation and growth with retarded entry into the S phase. Cav-2 re-expression in SH-SY5Y neuroblastoma cells and depletion in HeLa epithelial cervical cancer and A549 lung adenocarcinoma cells promoted cancer cell proliferation. Luciferase reporter assay showed that transcriptional activation of Elk-1 and STAT3 was significantly decreased in cav-2-transfected HepG2 hepatocellular carcinoma and down-regulated C6 glioma cells. Our data suggest that cav-2 acts as a modulator of cancer progression. Copyright © 2011 Spandidos Publications Ltd. All rights reserved.

Low P.A.,Mayo Medical School | Tomalia V.A.,Mayo Medical School | Park K.-J.,Gyeongsang National University
Journal of Clinical Neurology (Korea) | Year: 2013

Modern autonomic function tests can non-invasively evaluate the severity and distribution of autonomic failure. They have sufficient sensitivity to detect even subclinical dysautonomia. Standard laboratory testing evaluates cardiovagal, sudomotor and adrenergic autonomic functions. Cardiovagal function is typically evaluated by testing heart rate response to deep breathing at a defined rate and to the Valsalva maneuver. Sudomotor function can be evaluated with the quantitative sudomotor axon reflex test and the thermoregulatory sweat test. Adrenergic function is evaluated by the blood pressure and heart rate responses to the Valsalva maneuver and to head-up tilt. Tests are useful in defining the presence of autonomic failure, their natural history, and response to treatment. They can also define patterns of dysautonomia that are useful in helping the clinician diagnose certain autonomic conditions. For example, the tests are useful in the di-agnosis of the autonomic neuropathies and distal small fiber neuropathy. The autonomic neuropathies (such as those due to diabetes or amyloidosis) are characterized by severe generalized autonomic failure. Distal small fiber neuropathy is characterized by an absence of autonomic failure except for distal sudomotor failure. Selective autonomic failure (which only one system is affected) can be diagnosed by autonomic testing. An example is chronic idiopathic anhidrosis, where only sudomotor function is affected. Among the synucleinopathies, autonomic function tests can distinguish Parkinson's disease (PD) from multiple system atrophy (MSA). There is a gradation of autonomic failure. PD is characterized by mild autonomic failure and a length-dependent pattern of sudomotor involvement. MSA and pure autonomic failure have severe gen-eralized autonomic failure while DLB is intermediate. © 2013 Korean Neurological Association.

Jung E.J.,Gyeongsang National University | Kim D.R.,Gyeongsang National University
Biochemical and Biophysical Research Communications | Year: 2011

We previously reported that TrkA overexpression causes accumulation of γH2AX proteins in the cytoplasm, subsequently leading to massive cell death in U2OS cells. To further investigate how cytoplasmic H2AX is associated with TrkA-induced cell death, we established TrkA-inducible cells stably expressing GFP-tagged H2AX. We found that TrkA co-localizes with ectopically expressed GFP-H2AX proteins in the cytoplasm, especially at the juxta-nuclear membranes, which supports our previous results about a functional connection between TrkA and γH2AX in TrkA-induced cell death. γH2AX production from GFP-H2AX proteins was significantly increased when TrkA was overexpressed. Moreover, ectopic expression of H2AX activated TrkA-mediated signal pathways via up-regulation of TrkA tyrosine-490 phosphorylation. In addition, suppression of TrkA tyrosine-490 phosphorylation under a certain condition was removed by ectopic expression of H2AX, indicating a functional role of H2AX in the maintenance of TrkA activity. Indeed, TrkA-induced cell death was highly elevated by ectopic H2AX expression, and it was further accelerated by DNA damage via JNK activation. These all results suggest that cytoplasmic H2AX could play an important role in TrkA-mediated cell death by modulating TrkA upon DNA damage. © 2010 Elsevier Inc.

Kim Y.,Gyeongsang National University | Kim B.S.,Gyeongsang National University
IEEE Transactions on Aerospace and Electronic Systems | Year: 2013

The work presented here proposes two pitch autopilot designs for agile missiles which experience high pitch angles or angles of attack (AoA) during their manoeuvres. One great challenge pertaining to high AoA is that aerodynamic coefficients cannot be precisely predicted in a conventional wind tunnel environment. To directly address this challenge, the proposed autopilot designs (based on the integrator backstepping and H∞-norm minimization) do not require precise knowledge of such aerodynamic coefficients and so has a strong practical merit. Simulation results clearly testify this practical merit. © 1965-2011 IEEE.

Kim H.-M.,Gyeongsang National University | Kim G.-S.,Gyeongsang National University
International Journal of Precision Engineering and Manufacturing | Year: 2013

This paper describes the development of a finger-rehabilitation robot for rehabilitating stroke patients' fingers and other patient's paralyzed fingers. The developed finger-rehabilitation robot is composed of a thumb-rehabilitation robot instrument and four finger-rehabilitation robot instruments. The finger-rehabilitation robot could exercise fingers of patient for their rehabilitation, and it is a flexibility rehabilitation exercise. The finger-rehabilitation robot instruments move according to the trace which spread out the patient's fingers and then turn them inward for the fingers' flexibility, while at the same time performing the force control with the reference forces for fingers' safety. A control characteristic test of the developed finger-rehabilitation robot was carried out, and the result confirmed that the robot could be used for the flexibility rehabilitation exercise for the fingers of normal person and patients. © 2013 Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg.

Lee T.,Gyeongsang National University | Ouarda T.B.M.J.,Masdar Institute of Science and Technology | Ouarda T.B.M.J.,Canada Research Chair on the Estimation of Hydrometeorological Variables | Jeong C.,Induk University
Journal of Hydrology | Year: 2012

A multivariate stochastic generation model for daily weather variables is proposed that extends the multivariate . k-nearest neighbor resampling approach (MKNN). Major drawbacks of the MKNN approach include repetitive historical multivariate patterns, underestimating variance and serial correlation, and reshuffling of historical data. These drawbacks cause under-generation of events that are extreme in their frequency and magnitude. In this study, these drawbacks are addressed by applying a stochastic optimization technique (i.e., a genetic algorithm (GA)) and a perturbation using a gamma kernel density estimate (GKDE). The competitive selection operator in the GA was used to better preserve the historical variance and serial correlation as well as to produce unprecedented multivariate patterns. By employing the GKDE, the resampled precipitation data are perturbed, and thus new precipitation values are generated. To preserve the distribution of the annual maximum events fitted to a general extreme value (GEV), the GKDE bandwidth was selected by employing the statistics of the historical annual maximum. The proposed method was applied to generate six daily weather variables (maximum temperature, minimum temperature, dew point temperature, solar radiation, wind speed, and precipitation) of the summer season (June-September) for a station in Seoul, South Korea. The presented results indicate that the suggested weather generator is an appropriate alternative for generating daily weather variables while reproducing the historical extreme distribution. © 2012 Elsevier B.V.