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Simulation of Suspended Sediment in the Yellow and East China Seas

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China Ocean Engineering 2005年第2期19卷 235-250页

作者： CHOI Byung-Ho MUN Jong-Yoon ko jin-seok YUK jin-Hee Department of Civil and Environmental Engineering Sungkyunkwan University Suwon 440-746 KoreaKorea Ocean Science and Engineering Corporation 175-9 Huam-dong Yongsan-gu Seoul 140-901 KoreaHyein Engineering and Construction Co. Ltd. 150-057 761 Shingil 7 dong Yungdungpogu Seoul KoreaDepartment of Civil and Environmental Engineering Sungkyunkwan University Suwon 440-746 Korea

Described is an initial attempt to simulate the suspended sediment dynamics relating to tidal and wave forcing during summertime in June 1980 and August 1981 for the Yellow and East China Seas continental shelf. The cohesive/non-cohesive sediment resuspension and movement generated by the interaction between current and wave are modeled by use of ECOMSED and WAM Cycle 4. Model results are compared with observations in US-China Marine Sedimentation Dynamics Program performed for 1980-81 at off the Changjiang estuary. The main features of simulations show that suspended sediment concentrations during the summer decreased markedly offshore as observed during the simulation periods. As for some discrepancies for the mouth of the estuary with high river discharges, i.e., the Changjiang River, the model did not properly reproduce the over-mixing situation in the summer; thus distinct vertical concentration variation in this local region is not agreeable with observation. However, general dispersal patterns of suspended sediment movement seem to be agreeably reproduced for the nearshore shallow region. Some of the procedures of simulation and results are presented and discussed.

关键词： Yellow Sea East China Sea sediment transport model time slice experiment sediment concentration

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Journal of Materials Science & Technology 2022年第16期111卷 99-110页

作者： Vioni Dwi Sartika Won seok Choi Gwanghyo Choi Jaewook Han Sung-jin Chang Won-seok ko Blazej Grabowski Pyuck-Pa Choi Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Gangwon Regional Division Korea Institute of Industrial TechnologyGangwon 25440Republic of Korea Division of Measurement and Analysis National Nanofab CenterDaejeon 34141Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea Institute for Materials Science University of StuttgartPfaffenwaldring 5570569 StuttgartGermany

We report laser cladding of pure titanium on a CoCrMo alloy using directed energy *** electron microscopy,the microstructural evolution upon varying the process parameters,especially laser power and powder feed rate,was investigated in relation to crack *** layers showing dilution rates of more than 5%contained cracks due to the formation of the brittle Co_(2)Ti intermetallic *** observed cracks could be ascribed to a mismatch in thermal expansion and a resulting stress of more than 440 MPa acting on the Co_(2)Ti phase,as determined by density functional theory and ***,an excess laser energy caused chemical inhomogeneity and unmelted Ti powder particles,while a deficient laser energy resulted in a lack of *** cracks nor partially melted powders were observed for a powder feed rate of 3 g/min and a laser power of 225–300 W,for which the dilution rate was minimized to less than 5%.For such samples,the cladding layers comprised pureα-Ti and a uniform CoT i interface with Co_(2)Ti islands.

关键词： Additive manufacturing Dissimilar metal joining Titanium Cobalt-based alloy

Density functional theory study on the role of ternary alloying elements in TiFe-based hydrogen storage alloys

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Journal of Materials Science & Technology 2021年第33期92卷 148-158页

作者： Won-seok ko Ki Beom Park Hyung-Ki Park School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea Functional Materials and Components R&D Group Korea Institute of Industrial TechnologyGangneung 25440Republic of Korea

The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory *** a basic step for examinations,the site preference of each alloying element in the stoichiometric and nonstoichiometric B2TiFe compounds was clarified considering possible antisite *** on the revealed site preference,the effect of various possible ternary elements on the hydrogen storage was examined by focusing on the formation enthalpies of TiFeH and TiFeH_(2) hydrides,which were closely related to the change in the location of plateaus in the pressure-composition-temperature *** physical properties such as the volume expansion due to hydride formation were also examined to provide additional criteria for selecting optimum alloying conditions in future alloying design *** alloying elements that maximize the grain boundary embrittlement due to the solute segregation were proposed for the enhanced initial activation of TiFe-based hydrogen storage alloys.

关键词： Hydrogen storage alloy Titanium-iron Density functional theory calculation Metallic hydride

Multidimensional Hybrid Architecture Encapsulating Cobalt Oxide Nanoparticles into Carbon Nanotube Branched Nitrogen-Doped Reduced Graphene Oxide Networks for Lithium–Sulfur Batteries

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Energy & Environmental Materials 2022年第2期5卷 555-564页

作者： Jeong seok Yeon Young Hun ko Tae Ho Park Hyunyoung Park Jongsoon Kim Ho seok Park School of Chemical Engineering College of EngineeringSungkyunkwan University2066Seobu-roJangan-guSuwon-si Gyeonggi-do 440-746Korea Advanced Batteries Research Center Korea Electronics Technology Institute25Saenari-roBundang-guSeongnam-si Gyeonggi-do 13509Korea Department of Energy Science Sungkyunkwan University2066Seobu-roJangan-guSuwon-si Gyeonggi-do 440-746Korea Department of Health Sciences and Technology Samsung Advanced Institute for Health Sciences and Technology(SAIHST)Sungkyunkwan University2066SeoburoJangan-guSuwon 440-746South Korea

Lithium–sulfur batteries(LSBs)are regarded as promising candidates for the next-generation energy storage devices owing to their high-theoretical capacity(1675 mAh g^(−1))and affordable ***,several limitations of LSBs such as the lithium polysulfide shuttle,large volume expansion,and low electrical conductivity of sulfur need to be resolved for practical *** address these limitations,herein,a multidimensional architectured hybrid(Co@CNT/nG),where Co_(3)O_(4) nanoparticles are encapsulated into threedimensional(3D)porous N-doped reduced graphene oxide interconnected with carbon nanotube(CNT)branches,is synthesized through a simple pyrolysis *** synergistic effect achieved through the homogeneously distributed and encapsulated Co_(3)O_(4) nanoparticles,the interconnected CNT branches,and the 3D hierarchical porous structure and N-doping of Co@CNT/nG significantly suppresses the shuttle effect of lithium polysulfides and enhances the conversion redox kinetics for the improved sulfur *** validate this effect through various measurements including symmetric cells,Li_(2)S nucleation,shuttle currents,Tafel slopes,diffusion coefficients,and post-mortem ***,Co@CNT/nG-70S-based LSB cells achieve a high-specific capacity of 1193.1 mAh g^(−1) at 0.1 C and a low capacity decay rate of 0.030%per cycle for 700 cycles at 5 C,delivering a high areal capacity of 5.62 mAh cm^(−2) even with a loading of 6.5 mg cm^(−2).

关键词： graphene/CNT hybrid lithium-sulfur batteries multidimensional architecture nanoparticle encapsulation redox promoter

CNN-Based RF Fingerprinting Method for Securing Passive Keyless Entry and Start System

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Computers, Materials & Continua 2023年第8期76卷 1891-1909页

作者： Hyeon Park SeoYeon Kim seok Min ko TaeGuen Kim Department of Smart Convergence Security Soonchunhyang UniversityAsanKorea Department of Information Security Engineering Soonchunhyang UniversityAsanKorea

The rapid growth of modern vehicles with advanced technologies requires strong security to ensure customer *** key system that needs protection is the passive key entry system(PKES).To prevent attacks aimed at defeating the PKES,we propose a novel radio frequency(RF)fingerprinting *** method extracts the cepstral coefficient feature as a fingerprint of a radio frequency *** feature is then analyzed using a convolutional neural network(CNN)for device *** evaluation,we conducted experiments to determine the effectiveness of different cepstral coefficient features and the convolutional neural network-based *** experimental results revealed that the Gammatone Frequency Cepstral Coefficient(GFCC)was the most compelling feature compared to Mel-Frequency Cepstral Coefficient(MFCC),Inverse Mel-Frequency Cepstral Coefficient(IMFCC),Linear-Frequency Cepstral Coefficient(LFCC),and Bark-Frequency Cepstral Coefficient(BFCC).Additionally,we experimented with evaluating the effectiveness of our method in comparison to existing approaches that are similar to ours.

关键词： RF fingerprint cepstral coefficient convolutional neural network

Effects of ozonation and coagulation on effluent organic matter characteristics and ultrafiltration membrane fouling

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Journal of Environmental Sciences 2014年第6期26卷 1325-1331页

作者： Kwon Jeong Dae-Sung Lee Do-Gun Kim seok-Oh ko Department of Civil Engineering Kyung Hee UniversityYongin 446-701 Korea Institute of Construction Technology KUMHO Engineering & ConstructionYongin 449-822 Korea

Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.

关键词： effluent organic matter fouling ultrafiltration oxidation molecular weight distribution acidity

Role of kaempferol to increase bioavailability and pharmacokinetics of nifedipine in rats

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Chinese Journal of Natural Medicines 2019年第9期17卷 690-697页

作者： PARK Ji-Won CHOI jin-seok Hazardous Substances Analysis Division Gwangju Regional Office of Food and Drug SafetyGwangju 61012Republic of Korea Department of Medical Management Chodang UniversityJeollanam-do 58530Republic of Korea

Herein,the purpose of this study is to evaluate the effects of kaempferol on bioavailability and pharmacokinetics of nifedipine and its metabolite dehydronifedipine in *** experimental design is based on with or without kaempferol in the oral and intravenous administration of nifedipine in ***,the pharmacokinetic parameters including nifedipine and dehydronifedipine were evaluated in *** in vitro studies of kaempferol were investigated on P-glycoprotein(P-gp)and cytochrome P450(CYP)3A4 *** reduced a 50%inhibitory concentration(IC50)of 8.6μmol·L-1 on CYP3A4 enzyme ***,kaempferol clearly improved the cell internalization of rhodamine-123 in MCF-7/ADR cells overexpressing *** on increased concentrations of kaempferol,the areas under the plasma concentration–time curve(AUC0-∞)and the peak concentration(Cmax)of nifedipine were increased after oral and intravenous ***,the absolute bioavailability(AB)and relative bioavailability(RB)of nifedipine in the presence of kaempferol was significantly higher than those of the control group after oral and intravenous *** of bioavailability of nifedipine by kaempferol may be mainly because of the inhibition of the P-gp-mediated efflux transporter in the small intestine and CYP3A4-mediated metabolism in the small intestine or liver,or both.

关键词： Nifedipine Kaempferol CYP3A4 P-gp Pharmacokinetics Bioavailability

Effects of methotrexate on collagen-induced arthritis in male Wistar rats

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The Journal of Biomedical Research 2019年第4期33卷 244-249页

作者： jin seok Kang Department of Biomedical Laboratory Science Namseoul University

To evaluate the effect of methotrexate on collagen-induced arthritis,micro-computed tomography(micro-CT)and histopathological analyses were used in male Wistar *** were divided randomly into three *** 1 was treated with 0.9% saline,and groups 2 and 3 were boosted with type II *** day 21 to 42,groups 1 and 2 were orally treated with 0.9% saline and group 3 was orally treated with 1.5 mg/kg *** rats were sacrificed at day 42 after the first collagen ***-CT analyses showed bony parameters,such as bone volume and trabecular number,were decreased in group 2 compared to group 1,and these parameters were recovered in group *** examination and pathological parameter scoring showed that the knee joints of rats in group 2 had severe joint destruction,showing cartilage and bone erosion,enlarged cavities with inflammatory cell infiltration and activation of synovial *** contrast,these changes were reduced in group *** together,methotrexate treatment showed therapeutic potential in male rat collageninduced arthritis model,and micro-CT analysis and histopathological tools could be integrated to assess the quantification/qualification of arthritic lesions.

关键词： arthritis rat collagen micro-computed tomography histopathology

Homeostasis and regulation of autoreactive B cells

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Cellular & Molecular Immunology 2020年第6期17卷 561-569页

作者： Sujin Lee Yeunjung ko Tae jin Kim Department of Immunology Sungkyunkwan University School of MedicineSuwon 16419Republic of Korea

In contrast to the previous belief that autoreactive B cells are eliminated from the normal repertoire of B cells,many autoreactive B cells actually escape clonal deletion and develop into mature B *** autoreactive B cells in healthy individuals perform some beneficial functions in the host and are homeostatically regulated by regulatory T and B cells or other mechanisms to prevent autoimmune *** B-1 cells constitutively produce polyreactive natural antibodies for tissue ***,autoreactive follicular B cells were reported to participate actively in the germinal center ***,the selection and usefulness of autoreactive marginal zone(MZ)B cells found in autoimmune diseases are not well understood,although the repertoire of MZ B-cell receptors(BCRs)is presumed to be biased to detect bacterial *** this review,we discuss the autoreactive B-cell populations among all three major B-cell subsets and their regulation in immune responses and diseases.

关键词： B-cell autoreactivity polyreactivity autoreactive antibody B-cell receptor B-1 lymphocyte autoreactive germinal center autoreactive marginal zone B cell