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Mechanical and electrochemical characteristics evaluation in annealing treatment for ship material

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中国有色金属学会会刊：英文版 2009年第B9期19卷 40-44页

作者： seok-Ki JANG Young-Jae JEONG Seong-Jong kim Division of Marine Engineering Mokpo Maritime University Jeonnam Techno Park

The effect of heat treatment on the electrochemical and mechanical properties of SS400 steel was investigated, and the effects of annealing conditions on notched specimens subjected to the slow strain rate test (SSRT) were studied. The results show that no correlations are observed among the maximum tensile strength, yield strength, and stress corrosion cracking. In contrast, the elongation and time-to-fracture are improved with stress-relieving annealing compared with the as-received condition. The elongation, time-to-fracture, and number of dimples increase with annealing heat treatment.

关键词：退火处理电化学船舶材料特性评价机械 SS400钢应力腐蚀开裂消除应力退火

Boosting overall water splitting by incorporating sulfur into NiFe(oxy)hydroxide

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Journal of Energy Chemistry 2022年第1期31卷 364-371,I0010页

作者： Chiho kim Seong Hyun kim Seunghun Lee Ilyeong Kwon Seong Hyun kim Shinho kim Changgyu seok Yoo Sei Park Yangdo kim Department of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea BK21 Four Innovative Graduate Education Program for Global High-tech Materials&PartsPusan National UniversityBusan 46241Republic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH).Pohang 37673Republic of Korea

Developing highly active and cost-effective electrocatalysts for enhancing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a significant challenge for overall water ***-incorporated nickel iron(oxy)hydroxide(S-NiFeOOH)nanosheets were directly grown on commercial nickel foam using a galvanic corrosion method and a hydrothermal *** incorporation of sulfur into NiFeOOH enhanced the catalytic activity for the HER and OER in 1 M KOH *** enhanced catalytic activity is attributed to the change in the local structure and chemical states due to the incorporation of *** performance for overall water splitting was achieved with an alkaline water *** was realized by employing S-NiFeOOH as a bifunctional electrocatalyst,thereby outperforming a water electrolyzer that requires the usage of precious metal electrocatalysts(i.e.,Pt/C as the HER electrocatalyst and IrO_(2) as the OER electrocatalyst).Moreover,when driven by a commercial silicon solar cell,an alkaline water electrolyzer that uses S-NiFeOOH as a bifunctional electrocatalyst generated hydrogen under natural *** study shows that S-NiFeOOH is a promising candidate for a large-scale industrial implementation of hydrogen production for overall water splitting because of its low cost,high activity,and *** addition,the solar-driven water electrolyzer using S-NiFeOOH as a bifunctional electrocatalyst affords the opportunity for developing effective and feasible solar power systems in the future.

关键词： Overall water splitting Hydrogen production Sulfur incorporated NiFe(oxy)hydroxide Electrocatalysts Solar-driven water splitting

Roles of hepatocyte nuclear factors in hepatitis B virus infection

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World Journal of Gastroenterology 2016年第31期22卷 7017-7029页

作者： Doo Hyun kim Hong seok Kang Kyun-Hwan kim Department of Pharmacology and Center for Cancer Research and Diagnostic Medicine IBST School of Medicine Konkuk University KU Open Innovation Center Konkuk University Research Institute of Medical Science Konkuk University

Approximately 350 million people are estimated to be persistently infected with hepatitis B virus(HBV) worldwide. HBV maintains persistent infection by employing covalently closed circular DNA(ccc DNA), a template for all HBV RNAs. Chronic hepatitis B(CHB) patients are currently treated with nucleos(t)ide analogs such as lamivudine, adefovir, entecavir, and tenofovir. However, these treatments rarely cure CHB because they are unable to inhibit ccc DNA transcription and inhibit only a late stage in the HBV life cycle(the reverse transcription step in the nucleocapsid). Therefore, an understanding of the factors regulating ccc DNA transcription is required to stop this process. Among numerous factors, hepatocyte nuclear factors(HNFs) play the most important roles in ccc DNA transcription, especially in the generation of viral genomic RNA, a template for HBV replication. Therefore, proper control of HNF function could lead to the inhibition of HBV replication. In this review, we summarize and discuss the current understanding of the roles of HNFs in the HBV life cycle and the upstream factors that regulate HNFs. This knowledge will enable the identification of new therapeutic targets to cure CHB.

关键词： Hepatitis B virus Hepatocyte nuclear factor Covalently closed circular DNA Replication

Impregnation approach for poly(vinylidene fluoride)/tin oxide nanotube composites with high tribological performance

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Journal of Materials Science & Technology 2020年第2期37卷 19-25页

作者： Min Su Park Jin Kyu kim Tong-seok Han Jung Tae Park Jong Hak kim Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Korea Department of Civil and Environmental Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Korea Department of Chemical Engineering Konkuk University120 Neungdong-roGwangjin-guSeoul05029Korea

We report a composite material with the high tribological performance,which consists of onedimensional SnO2 nanotubes(ST)and a high molecular weight poly(vinylidene fluoride)(PVDF)matrix in terms of *** of PVDF in N,N-dimethylformamide(DMF)resulted in a facile penetration of PVDF into the inner hollow voids of ST,leading to the close *** between PVDF and ST results in a beneficial effect on the chain arrangement of PVDF,providing anα-phase with better tribological *** ST incorporation,the friction coefficient decreased by 85.0%to 0.408,and the specific wear rate decreased by 69.1%to 0.412,demonstrating the pivotal role of ST as a self-lubricating material due to a large interactive area and PVDF chain rearrangement.

关键词： SnO2 nanotube Composite Friction coefficient Wear rate

Structural optimization for ball valve made of CF8M stainless steel

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中国有色金属学会会刊：英文版 2009年第B9期19卷 258-261页

作者： Seung-Gyu kim seok-Heum BAEK Young-Chul PARK Department of Mechanical Engineering Dong-A University

The mechanical and chemical properties of CF8M were studied through experiments. An application of CF8M in valve body was analyzed by using finite element method(FEM) to evaluate the structural safety. An optimization containing several variables based on the response surface method(RSM) was conducted to find the optimum dimension of the valve. The results show that using this process can save valve mass as well as the computational expense effectively.

关键词：结构优化球阀不锈钢化学性能有限元法结构安全最佳尺寸 FEM

Effects of Gastrodiae rhizoma on proliferation and differentiation of human embryonic neural stem cells

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Asian Pacific Journal of Tropical Medicine 2015年第10期8卷 776-781页

作者： Samrat Baral Ramesh Pariyar Chi-Su Yoon Dong-Cheol kim Jong-Min yun seok O Jang Sung Yeon kim Hyuncheol Oh Youn-Chul kim Jungwon Seo From the BK21 Plus Team Institute of Pharmaceutical Research and Development College of PharmacyWonkwang University Professional Graduate School of Oriental Medicine Wonkwang University Hanbang Body-Fluid Research Center Wonkwang University Standardized Material Bank for New Botanical Drugs College of PharmacyWonkwang University Department of Internal Medicine College of Korean MedicineWonkwang University

Objective:To investigate the effects of Gastrodiae rhizoma,a dried root of Gastrodia elata Blume,on proliferation and differentiation of human NSCs derived from embryonic stem ***:A 70%ethanol extract of Gastrodiae rhizoma(EEGR) was estimated with4-hydroxybenzyl alcohol as a representative constituent by ***:MTT assay showed that the treatment with EEGR increased the viability of NSCs in growth *** to contro1,EEGR increased the number of dendrites and denritic spines extended from a differentiated *** EEGR decreased the mRNA expression of Nestin,it increased that of Tuj1 and MAP2 in NSCs grown in differentiation *** analysis using confocal microscopy also revealed the increased expression of MAP2 in dendrites of EEGR-treated ***,EEGR decreased mRNA expression of Sox2 in NSCs grown even in growth ***:In conclusion,our study demonstrates for the first time that EEGR induced proliferation and neuronal differentiation of NSCs,suggesting its potential benefits on NSC-based therapies and neuroregeneration in various neurodegenerative diseases and brain Injuries.

关键词： Gastrodiac rhizoma Neural stem cells Neuronal diff

Enhancement of ballistic performance enabled by transformation-induced plasticity in high-strength bainitic steel

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Journal of Materials Science & Technology 2021年第25期84卷 219-229页

作者： Min Cheoljo Selim kim Dong Woo Suh Hong Kyu kim Yongjin kim seok Su Sohn Sunghak Lee Center for Advanced Aerospace Materials Pohang University of Science and TechnologyPohang37673South Korea Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang37673South Korea Materials Directorate Agency for Defense DevelopmentDaejeon305-600South Korea Department of Materials Science and Engineering Korea UniversitySeoul02841South Korea

High-strength bainitic steels have created a lot of interest in recent times because of their excellent combination of strength,ductility,toughness,and high ballistic mass *** steels have great potential in the fabrication of steel armor *** various approaches and methods have been conducted to utilize the retained austenite(RA)in the bainitic matrix to control mechanical properties,very few attempts have been conducted to improve ballistic performance utilizing transformationinduced plasticity(TRIP)*** this study,high-strength bainitic steels were designed by controlling the time of austempering process to have various volume fractions and stability of RA while maintaining high *** dynamic compressive and ballistic impact tests were conducted,and the relation between the effects of TRIP on ballistic performance and the adiabatic shear band(ASB)formation was *** results show for the first time that an active TRIP mechanism achieved from a large quantity of metastable RA can significantly enhance the ballistic performance of high-strength bainitic steels because of the improved resistance to ASB ***,the ballistic performance can be effectively improved by a very short austempering time,which suggests that the utilization of active TRIP behavior via tuning RA acts as a primary mechanism for significantly enhancing the ballistic performance of high-strength bainitic steels.

关键词： High-strength bainitic steel Ballistic performance Split Hopkinson pressure bar(SHPB) Adiabatic shear band(ASB) Retained austenite(RA) Transformation-induced plasticity(TRIP)

Uncertainty analysis of flow rate measurement for multiphase flow using CFD

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Acta Mechanica Sinica 2015年第5期31卷 698-707页

作者： Joon-Hyung kim Uk-Hee Jung Sung kim Joon-Yong Yoon Young-seok Choi Department of Mechanical Design Engineering Hanyang University Thermal & Fluid System R&BD Group Korea Institute of Industrial Technology Energy System Engineering University of Science and Technology

The venturi meter has an advantage in its use,because it can measure flow without being much affected by the type of the measured fluid or flow ***,it has excellent versatility and is being widely applied in many *** flow of a liquid containing air is a representative example of a multiphase flow and exhibits complex flow *** particular,the greater the gas volume fraction（GVF）,the more inhomogeneous the flow *** a result,using a venturi meter to measure the rate of a flow that has a high GVF generates an *** this study,the cause of the error occurred in measuring the flow rate for the multiphase flow when using the venturi meter for analysis by *** ensure the reliability of this study,the accuracy of the multiphase flow models for numerical analysis was verified through comparison between the calculated results of numerical analysis and the experimental *** a result,the Grace model,which is a multiphase flow model established by an experiment with water and air,was confirmed to have the highest ***,the characteristics of the internal flow Held about the multiphase flow analysis result generated by applying the Grace model were analyzed to find the cause of the uncertainty occurring when measuring the flow rate of the multiphase flow using the venturi meter.A phase separation phenomenon occurred due to a density difference of water and air inside the venturi,and flow inhomogeneity happened according to the flow velocity difference of each *** was confirmed that this flow inhomogeneity increased as the GVF increased due to the uncertainty of the flow measurement.

关键词： Multiphase flow Measurement Numerical analysis Venturi meter Gas volume fraction(GVF) Uncertainty Multiphase flow model Grace model

Laser particles with omnidirectional emission for cell tracking

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Light(Science & Applications) 2021年第2期10卷 197-207页

作者： Shui-Jing Tang Paul H.Dannenberg Andreas C.Liapis Nicola Martino Yue Zhuo yun-Feng Xiao seok-Hyun yun Harvard Medical School and Wellman Center for Photomedicine Massachusetts General HospitalBostonMAUSA State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking University100871 BeijingChina Harvard-MIT Health Sciences and Technology Massachusetts Institute of TechnologyCambridgeMAUSA

The ability to track individual cells in space over time is crucial to analyzing heterogeneous cell ***,microlaser particles have emerged as unique optical probes for massively multiplexed single-cell ***,the microlaser far-field emission is inherently direction-dependent,which causes strong intensity fluctuations when the orientation of the particle varies randomly inside ***,we demonstrate a general solution based on the incorporation of nanoscale light scatterers into *** schemes are developed by introducing either boundary defects or a scattering layer into microdisk *** resulting laser output is omnidirectional,with the minimum-to-maximum ratio of the angle-dependent intensity improving from 0.007(-24 dB)to>0.23(-6dB).After transfer into live cells in vitro,the omnidirectional laser particles within moving cells could be tracked continuously with high signal-to-noise ratios for 2 h,while conventional microlasers exhibited frequent signal loss causing tracking failure.

关键词： scattering directional intensity