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Densification simulation of compacted Al powders using multi-particle finite element method

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中国有色金属学会会刊：英文版 2009年第B9期19卷 68-75页

作者： Kyung-Hun lee jung-min lee Byung-min KIM School of Mechanical Engineering Pu san National University

The powder compaction simulations were performed to demonstrate deformation behavior of particles and estimate the effect of different punch speeds and particle diameters on the relative density of powder by a multi-particle finite element model(MPFEM). Individual particle discretized with a finite element mesh allows for a full description of the contact mechanics. In order to verify the reliability of compaction simulation by MPFEM, the compaction tests of porous aluminum with average particle size of 20 μm and 3 μm were performed at different ram speeds of 5, 15, 30 and 60 mm/min by MTS servo-hydraulic tester. The results show that the slow ram speed is of great advantage for powder densification in low compaction force due to sufficient particle rearrangement and compaction force increases with decrease in average particle size of aluminum.

关键词：粉末压实粉末粒子多孔铝有限元法模拟致密化平均粒径有限元模型

Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

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中国有色金属学会会刊：英文版 2012年第S3期22卷 585-595页

作者： jung-min lee Chan-Joo lee Kyung-Hun lee Byung-min KIM Dongnam Regional Division Korea Institute of Industrial Technology Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the ***,this indirect measurement occasionally leads to inaccurate properties of the indented *** objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation *** relations between the residual indentation profile and n value of the indented material were identified by dimensional ***,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and *** parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after *** were subsequently characterized as dimensionless functions using n and E/σr ***,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

关键词： nano-indentation pile-up sink-in strain hardening exponent FE simulation

Deformation prediction of porcelain-enameled steels with strain history by press forming and high-temperature behavior of coating layer

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中国有色金属学会会刊：英文版 2012年第S3期22卷 838-844页

作者： Young-Ki SON Chan-Joo lee jung-min lee Byung-min KIM School of Mechanical Engineering Pusan National University Dongnam Regional Division Korea Institute of Industrial Technology

Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of *** typical process to produce enameled steels is roughly divided into two stages:the first stage consists of a forming process to give the desired shape to a steel substrate,and the second stage consists of a firing process to bond enamel frits on the *** firing process requires a high temperature above 800 °C,which may lead to austenitic transformation and severe thermal deformation of the steel *** aim of this study is to develop a finite element analysis (FE analysis) technique to predict the mechanical and thermal deformations of the enameled steels during forming and any further enameling process,including *** FE analysis involves analyzing the strain history of the steel substrate,which comprises the stress and thickness distributions of the substrate and its deformed shape,and the high-temperature behavior of the enamel coating *** validity of the FE analysis is verified through the U-bending test and firing test with various numbers and positions of enamel coating layers on the *** results reveal that the FE analysis results agree well with the experimental results with 8% error.

关键词： porcelain enamel firing process finite element analysis enameled steel thermal deformation

Quantification of HBsAg:Basic virology for clinical practice

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World Journal of Gastroenterology 2011年第3期17卷 283-289页

作者： jung min lee Sang Hoon Ahn Department of Internal Medicine Yonsei University College of Medicine Department of Internal Medicine Institute of GastroenterologyYonsei University College of Medicine Liver Cirrhosis Clinical Research Center

Hepatitis B surface antigen (HBsAg) is produced and secreted through a complex mechanism that is still not fully understood. In clinical fields, HBsAg has long served as a qualitative diagnostic marker for hepatitis B virus infection. Notably, advances have been made in the development of quantitative HBsAg assays, which have allowed viral replication monitoring, and there is an opportunity to make maximal use of quantitative HBsAg to elucidate its role in clinical fields. Yet, it needs to be underscored that a further understanding of HBsAg, not only from clinical point of view but also from a virologic point of view, would enable us to deepen our insights, so that we could more widely expand and apply its utility. It is also important to be familiar with HBsAg variants and their clinical consequences in terms of immune escape mutants, issues resulting from overlap with corresponding mutation in the P gene, and detection problems for the HBsAg variants. In this article, we review current concepts and issues on the quantification of HBsAg titers with respect to their biologic nature, method principles, and clinically relevant topics.

关键词：乙肝表面抗原临床实践病毒学乙型肝炎表面抗原 HBsAg 基因突变生物学特性病毒感染

Tetramic acid-motif natural products from a marine fungus Tolypocladium cylindrosporum FB06 and their anti-Parkinson activities

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Marine Life Science & Technology 2024年第1期6卷 84-92页

作者： Yuna jung Chaesun Kwon Taeyeon Kim Jin Woo lee min-Kyoo Shin Sang Hee Shim Natural Products Research Institute College of PharmacySeoul National UniversitySeoul 08826Republic of Korea College of Pharmacy and Research Institute of Pharmaceutical Sciences Seoul National UniversitySeoul 08826Republic of Korea College of Pharmacy Duksung Women’s UniversitySeoul 01369Republic of Korea

Tetramic acid-containing natural products are attracting significantly increasing attention from biologists and chemists due to their intriguing structures and biological *** the present study,two new tetramic acid alkaloids tolypyridone I(1)and tolypyridone J(2),together with five known ones(3–7),were isolated from cultures of a marine fungus Tolypocladium cylindrosporum FB06 isolate obtained from a marine sediment in Beaufort sea of North *** structures were elucidated using 1D,2D NMR,and *** configurations were established on the basis of 1H coupling constants,ROESY correlations and DP4 *** 2 was isolated as mixtures of rotational isomers with C-3 to C-7 axis between 4-hydroxy-2-pyridone and 1-ethyl-3,5-dimethylcyclohexane,hindering *** our unbiased screening to discover neuroprotective compounds in an in vitro Parkinson’s disease(PD)model,SH-SY5Y dopaminergic cells were treated with isolated compounds followed by treatment with 1-methyl-4-phenylpyridinium(MPP^(+)),a parkinsonian *** tested compounds,F-14329(7)significantly protected cells from MPP^(+)-induced ***^(+)-mediated cell death is known to be related to the regulation of Bcl-2 family proteins,specifically the down-regulation of anti-apoptotic Bcl-2 and the up-regulation of pro-apoptotic Bax *** with 2 mmol/L of MPP^(+)for 24 h significantly reduced Bcl-2 levels compared to control treated with ***,treatment with F-14329(7)attenuated such *** study demonstrates that tetramic acid-motif compounds could be potential lead compounds for treating PD.

关键词： Tolypocladium cylindrosporum Tetramic acid Tolypyridone Parkinson’s disease

Adverse effects of early-life stress:focus on the rodent neuroendocrine system

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Neural Regeneration Research 2024年第2期19卷 336-341页

作者： Seung Hyun lee Eui-Man jung Department of Molecular Biology College of Natural SciencesPusan National UniversityBusanRepublic of Korea

Early-life stress is associated with a high prevalence of mental illnesses such as post-traumatic stress disorders,attention-deficit/hyperactivity disorder,schizophrenia,and anxiety or depressive behavior,which constitute major public health *** the early stages of brain development after birth,events such as synaptogenesis,neuron maturation,and glial differentiation occur in a highly orchestrated manner,and external stress can cause adverse long-term effects throughout *** body utilizes multifaceted mechanisms,including neuroendocrine and neurotransmitter signaling pathways,to appropriately process external *** individuals first exposed to early-life stress deploy neurogenesis as a stress-defense mechanism;however,in adulthood,early-life stress induces apoptosis of mature neurons,activation of immune responses,and reduction of neurotrophic factors,leading to anxiety,depression,and cognitive and memory *** process involves the hypothalamus-pituitary-adrenal axis and neurotransmitters secreted by the central nervous system,including norepinephrine,dopamine,and *** rodent early-life stress model is generally used to experimentally assess the effects of stress during *** paper reviews the use of the early-life stress model and stress response mechanisms of the body and discusses the experimental results regarding how early-life stress mediates stress-related pathways at a high vulnerability of psychiatric disorder in adulthood.

关键词： early-life stress hypothalamic-pituitary-adrenergic axis maternal separation mental illness neurodevelopmental disorder neuroendocrine system neurotransmitter

Weighted Forwarding in Graph Convolution Networks for Recommendation Information Systems

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Computers, Materials & Continua 2024年第2期78卷 1897-1914页

作者： Sang-min lee Namgi Kim Department of Computer Science Kyonggi UniversitySuwonKorea

Recommendation Information Systems(RIS)are pivotal in helping users in swiftly locating desired content from the vast amount of information available on the *** Convolution Network(GCN)algorithms have been employed to implement the RIS ***,the GCN algorithm faces limitations in terms of performance enhancement owing to the due to the embedding value-vanishing problem that occurs during the learning *** address this issue,we propose a Weighted Forwarding method using the GCN(WF-GCN)*** proposed method involves multiplying the embedding results with different weights for each hop layer during graph *** applying the WF-GCN algorithm,which adjusts weights for each hop layer before forwarding to the next,nodes with many neighbors achieve higher embedding *** approach facilitates the learning of more hop layers within the GCN *** efficacy of the WF-GCN was demonstrated through its application to various *** the MovieLens dataset,the implementation of WF-GCN in LightGCN resulted in significant performance improvements,with recall and NDCG increasing by up to+163.64%and+132.04%,***,in the *** dataset,LightGCN using WF-GCN enhanced with WF-GCN showed substantial improvements,with the recall and NDCG metrics rising by up to+174.40%and+169.95%,***,the application of WF-GCN to Self-supervised Graph Learning(SGL)and Simple Graph Contrastive Learning(SimGCL)also demonstrated notable enhancements in both recall and NDCG across these datasets.

关键词： Deep learning graph neural network graph convolution network graph convolution network model learning method recommender information systems

Generation of double knockout cattle via CRISPR-Cas9 ribonucleoprotein(RNP)electroporation

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Journal of Animal Science and Biotechnology 2024年第1期15卷 456-462页

作者： Gyeong-min Gim Kyeong-Hyeon Eom Dong-Hyeok Kwon Dae-Jin jung Dae-Hyun Kim Jun-Koo Yi Jae-jung Ha Ji-Hyun lee Seong-Beom lee Woo-Jae Son Soo-Young Yum Won-Wu lee Goo Jang Laboratory of Theriogenology and Biotechnology Department of Veterinary Clinical ScienceCollege of Veterinary Medicine and the Research Institute of Veterinary ScienceSeoul National UniversitySeoulRepublic of Korea LARTBio Co. Ltd.SeoulRepublic of Korea Gyeongsangbukdo Livestock Research Institute YeongjuRepublic of Korea Comparative Medicine Disease Research Center Seoul National UniversitySeoulRepublic of Korea

Background Genome editing has been considered as powerful tool in agricultural ***,genome editing progress in cattle has not been fast as in other mammal species,for some disadvantages including long gestational periods,single pregnancy,and high raising ***,technically demanding methods such as microinjection and somatic cell nuclear transfer(SCNT)are needed for gene editing in *** this point of view,electroporation in embryos has been risen as an *** First,editing efficiency of our electroporation methods were tested for *** of mutation on embryo was confirmed by T7E1 *** first combination,mutation rates for MSTN and PRNP were 57.6%±13.7%and 54.6%±13.5%,*** case of MSTN/BLG,mutation rates were 83.9%±23.6%for MSTN,84.5%±18.0%for ***,the double-KO embryos were transferred to surrogates and mutation rate was identified in resultant calves by targeted deep *** recipients were transferred for MSTN/PRNP,4 calves were delivered,and one calf underwent an induction for double *** surrogates were given double-KO embryos for MSTN/BLG,and four of the six calves that were born had mutations in both *** These data demonstrated that production of genome edited cattle via electroporation of RNP could be effectively ***,MSTN and PRNP from beef cattle and MSTN and BLG from dairy cattle have been born and they will be valuable resources for future precision breeding.

关键词： Beta-lactoglobulin Cattle CRISPR-Cas9 Electroporation Knockout MSTN PRNP

Omni-functional simultaneous interfacial treatment for enhancing stability and outgassing suppression of lithium-ion batteries

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Journal of Energy Chemistry 2024年第7期94卷 677-687页

作者： Youbean lee Chanjoo Park Kyoungmin min Kwangjin Park Department of Mechanical Engineering Gachon UniversityGyeonggi-do 13120Republic of Korea Department of Battery Engineering Gachon UniversityGyeonggi-do 13120Republic of Korea School of Mechanical Engineering Soongsil UniversitySeoul 06978Republic of Korea

Ni-rich layered oxides in lithium-ion batteries have problems with gas generation and electrochemical performance reduction due to residual lithium's reaction on the surface with the *** address this issue,in this study,the Acid solvent evaporation(AsE)method has been proposed as a potential method to remove residual lithium while promoting the formation of a new LiNO_(3)-derived coating layer on the cathode *** reduction of residual lithium using the ASE method and the construction of a LiNO_(3)-derived coating layer suppresses gas evolution caused by the side effects of the electrolyte,improves electrochemical performance,and improves thermal stability by facilitating the smooth movement of lithium ***,the structural stability and resistance change due to the LiNO_(3)-derived coating layer effects is guaranteed through cycling and DCIR of the pouch *** a result,compared to Pristine,the capacity retention of coin cells increased by 8%after 100 cycles,and pouch cells increased by 25%after 160 *** addition,after cycling the pouch cell,CO_(2) gas has significantly reduced by about 30%compared to Pristine using gas *** ASE method effectively forms a robust LiNO_(3)-derived coating layer on the cathode active material,which helps minimize electrolyte reactivity,suppress ,CO_(2) emissions,enhance surface structure stability,improve thermal stability,and improveoverallbatteryperformance.

关键词： Lithium-ion batteries Ni-rich NCM Acid solvent evaporation LiNO_(3)-derived coating Gasevolution