Gwangju, South Korea

Gwangju National University of Education is a national university located in Gwangju, South Korea. Wikipedia.

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Kim Y.G.,Gwangju National University of Education | Lee H.M.,CERN
Journal of High Energy Physics | Year: 2011

We consider sneutrino inflation and post-inflation cosmology in the singlet extension of the MSSM with approximate Peccei-Quinn(PQ) symmetry, assuming that supersymmetry breaking is mediated by gauge interaction. The PQ symmetry is broken by the intermediate-scale VEVs of two flaton fields, which are determined by the interplay between radiative flaton soft masses and higher order terms. Then, from the flaton VEVs, we obtain the correct μ term and the right-handed(RH) neutrino masses for see-saw mechanism. We show that the RH sneutrino with non-minimal gravity coupling drives inflation, thanks to the same flaton coupling giving rise to the RH neutrino mass. After inflation, extra vector-like states, that are responsible for the radiative breaking of the PQ symmetry, results in thermal inflation with the flaton field, solving the gravitino problem caused by high reheating temperature. Our model predicts the spectral index to be ns ? 0.96 due to the additional efoldings from thermal inflation. We show that a right dark matter abundance comes from the gravitino of 100 keV mass and a successful baryogenesis is possible via Affleck-Dine leptogenesis. © 2011 SISSA.

Sohn K.H.,Gwangju National University of Education | Kim M.K.,Gimcheon College | Lee S.M.,Gimcheon College | Ji B.C.,Gimcheon College | And 3 more authors.
Fibers and Polymers | Year: 2011

Triphenyl phosphate (TPP) is well known to be one of the most effective flame retardants for acrylonitrile-butadiene-styrene copolymer (ABS) and its blending resins, such as polycarbonate (PC)/ABS, among various phosphorous-based compounds. However, TPP can also play a role as a plasticizer, which decreases the mechanical properties of PC/ABS resins at high temperature. Furthermore considerable amount of TPP has to be evaporated during molding process due on its much lower evaporation temperature. To overcome these shortcomings, we tried to immobilize TPP by grafting on butadiene moiety of ABS. FT-IR analysis of prepared TPP-grafted ABS (ABS-g-TPP) comparing with TPP, ABS and their blend confirmed that chemical reactions happened between TPP and ABS resins and it was attributed to the graft reaction of TPP onto butadiene moieties. Prepared ABS-g-TPP resins were blended with PC at various compositions to be prepared as testing specimens by injection molding. The physical characteristics such as mechanical properties, thermal stability, and flame retarding properties of the PC/ABS-TPP graft copolymer were analyzed through Vicat softening temperature, IZOD impact strength, transmission electron microscope, and UL94 flame retardation tests. Results showed that PC/ABS-g-TPP resin takes better thermomechanical properties than the existing PC/ABS resins at relatively low additional TPP amounts. © 2011 The Korean Fiber Society and Springer Netherlands.

Jeon K.,Gwangju National University of Education | Jarrett O.S.,Georgia State University | Ghim H.D.,Kyungpook National University
International Journal of Engineering Education | Year: 2014

This preliminary study explores the feasibility of incorporating theARCS(Attention-Relevance-Confidence-Satisfaction) model of motivation into project based learning (PBL) in a college engineering course on Functional Fibrous Biomaterials. The project involved design of wearable computers and consisted of five stages, orientation, identifying and defining, planning, implementing, and reporting and evaluating. The students worked in self-selected small single-gender groups to design their projects. According to the authors, it was feasible to incorporate ARCS into PBL, and the instructor was satisfied with the quality of the projects. An ARCS-based assessment tool, the Instructional Materials Motivation Scale (IMMS), found that the lowest scores were on confidence.Menrated attention, relevance, and satisfaction as above neutral but that women's ratings were below at least slightly below neutral on attention, confidence, and satisfaction and lower than men on all four aspects of motivation. Educational implications are discussed. © 2014 TEMPUS Publications.

PubMed | Gwangju National University of Education, Korea University and Chonnam National University
Type: | Journal: Computers in biology and medicine | Year: 2016

In this paper, an orthogonal Tucker-decomposition-based extraction of high-order discriminative subspaces from a tensor-based time series data structure is presented, named as Tensor Discriminative Feature Extraction (TDFE). TDFE relies on the employment of category information for the maximization of the between-class scatter and the minimization of the within-class scatter to extract optimal hidden discriminative feature subspaces that are simultaneously spanned by every modality for supervised tensor modeling. In this context, the proposed tensor-decomposition method provides the following benefits: i) reduces dimensionality while robustly mining the underlying discriminative features, ii) results in effective interpretable features that lead to an improved classification and visualization, and iii) reduces the processing time during the training stage and the filtering of the projection by solving the generalized eigenvalue issue at each alternation step. Two real third-order tensor-structures of time series datasets (an epilepsy electroencephalogram (EEG) that is modeled as channelfrequency bintime frame and a microarray data that is modeled as genesampletime) were used for the evaluation of the TDFE. The experiment results corroborate the advantages of the proposed method with averages of 98.26% and 89.63% for the classification accuracies of the epilepsy dataset and the microarray dataset, respectively. These performance averages represent an improvement on those of the matrix-based algorithms and recent tensor-based, discriminant-decomposition approaches; this is especially the case considering the small number of samples that are used in practice.

PubMed | Gwangju National University of Education, CAS Chengdu Institute of Biology and Inha University
Type: Journal Article | Journal: Journal of plant research | Year: 2016

The dynamic changes in land configuration during the Quaternary that were accompanied by climatic oscillations have significantly influenced the current distribution and genetic structure of warm-temperate forests in East Asia. Although recent surveys have been conducted, the historical migration of forest species via land bridges and, especially, the origins of Korean populations remains conjectural. Here, we reveal the genetic structure of Lespedeza buergeri, a warm-temperate shrub that is disjunctively distributed around the East China Sea (ECS) at China, Korea, and Japan. Two non-coding regions (rpl32-trnL, psbA-trnH) of chloroplast DNA (cpDNA) and the internal transcribed spacer of nuclear ribosomal DNA (nrITS) were analyzed for 188 individuals from 16 populations, which covered almost all of its distribution. The nrITS data demonstrated a genetic structure that followed geographic boundaries. This examination utilized AMOVA, comparisons of genetic differentiation based on haplotype frequency/genetic mutations among haplotypes, and Mantel tests. However, the cpDNA data showed contrasting genetic pattern, implying that this difference was due to a slower mutation rate in cpDNA than in nrITS. These results indicated frequent migration by this species via an ECS land bridge during the early Pleistocene that then tapered gradually toward the late Pleistocene. A genetic isolation between western and eastern Japan coincided with broad consensus that was suggested by the presence of other warm-temperate plants in that country. For Korean populations, high genetic diversity indicated the existence of refugia during the Last Glacial Maximum on the Korean Peninsula. However, their closeness with western Japanese populations at the level of haplotype clade implied that gene flow from western Japanese refugia was possible until post-glacial processing occurred through the Korea/Tsushima Strait land bridge.

Kim Y.G.,Gwangju National University of Education | Kim Y.G.,Korea Institute for Advanced Study | Lee K.Y.,Gyeongsang National University | Park C.B.,Korea Institute for Advanced Study | Shin S.,Indiana University Bloomington
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We examine the possibility that the dark matter (DM) interpretation of the GeV scale Fermi gamma-ray excess at the Galactic center can be realized in a specific framework-secluded singlet fermionic dark matter model with small mixing between the dark and Standard Model sectors. Within this framework, it is shown that the DM annihilation into a bottom-quark pair, Higgs pair, and new scalar pair, shown to give good fits to the Fermi gamma-ray data in various model independent studies, can be successfully reproduced in our model. Moreover, unavoidable constraints from the antiproton ratio by PAMELA and AMS-02, the gamma-ray emission from the dwarf spheroidal galaxies by the Fermi-LAT, and the Higgs measurements by the LHC are also considered. Then, we find our best-fit parameters for the Fermi gamma-ray excess without conflicting other experimental and cosmological constraints if uncertainties on the DM density profile of the Milky Way Galaxy are taken into account. Successfully surviving parameters are benchmark points for future study on the collider signals. © 2016 American Physical Society.

Kim Y.G.,Gwangju National University of Education | Lee K.Y.,Gyeongsang National University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We study the phenomenology of heavy gauge bosons at the LHC in a nonuniversal gauge interaction model with the separate electroweak SU(2) gauge group for the third generation. Considered are the Drell-Yan processes into the final states of dilepton, dijet, τ-τ+, and tt¯ for the Z′ boson and those of the lepton-neutrino for the W′ boson. We find that the present LHC data provides the most stringent lower bounds on the masses of the heavy gauge bosons, mZ′>1.8TeV for sin2φ>0.07 and mW′>2TeV for sin2φ>0.15, where φ is the mixing angle of two SU(2) gauge groups. © 2014 American Physical Society.

PubMed | Gwangju National University of Education and Chungnam National University
Type: Journal Article | Journal: Journal of assisted reproduction and genetics | Year: 2016

The aim of this study is to investigate the effect of acteoside, an antioxidant, on in vitro maturation (IVM) of oocytes to improve early parthenogenetic embryonic developmental competence.Porcine immature oocytes (total 770) were cultured in IVM medium with acteoside at various concentrations, 0 (control), 10, 30, and 50M. Each group was assessed for maturation and subsequent development rates, reactive oxygen species (ROS) level (15 oocytes per group and four independent experiments performed), ultrastructure observation (15 oocytes per group), mitochondrial activity (30 oocytes per groups and three independent experiments performed), and expression patterns of apoptosis-related genes (100 expended parthenogenetic embryos per group and three independent experiment performed). Main outcome measures were the rates of IVM, blastocyst formation, ROS, mitochondria, and expression of apoptosis-related genes in oocytes treated with acteoside.Addition of acteoside during IVM did not change the maturation efficiency of oocytes but improved the rate of blastocyst formation with significantly decreased ROS level. Moreover, in acteoside-treated oocytes, cytoplasmic maturation was improved with morphologically uniform distribution of mitochondria and lipid droplets in cytoplasm. Acteoside supplementation also increased the mRNA expression levels of antiapoptotic genes and reduced those of pro-apoptotic genes.Acteoside supplementation in IVM medium improves the oocyte quality and subsequent development of pre-implantation embryos that would eventually contribute to produce embryos with high embryonic development competence.

Kim Y.G.,Gwangju National University of Education
Modern Physics Letters A | Year: 2011

We investigate a squark cascade decay, i.e. q̄L→qx̄ 2→qZx̄1→qllx̄1. It is shown that some information on the mass and spin of the supersymmetric particles might be obtained from the cascade decay chain at the Large Hadron Collider at CERN. © 2011 World Scientific Publishing Company.

Kim Y.G.,Gwangju National University of Education | Lee K.Y.,Konkuk University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We study the phenomenology of the heavy charged gauge boson and obtain the lower bounds on its mass with the early LHC data at 7 TeV center-of-mass energy in the nonuniversal gauge interaction model, in which the electroweak SU(2) gauge group depends upon the fermion family. We found that the direct bound with the early data of the LHC is already better than the indirect bound on the mass of the W' boson. © 2011 Elsevier B.V.

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