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Energy & Environmental Materials 2024年第4期7卷 396-403页

作者： Myeong-Hyeon kim Sang-joon Park Tae-Jun Ha Department of Electronic Materials Engineering Kwangwoon UniversitySeoul 01897Korea

In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride(PVDF)films incorporated with cobalt-based metal-organic framework(Co-MOF)were *** enhanced output performance of the TENGs was attributed to the phase transition of PVDF from a-crystals toβ-crystals,as facilitated by the incorporation of the *** synthesis conditions,including metal ion,concentration,and particle size of the MOF,were optimized to increase open-circuit voltage(VOC)and open-circuit current(I_(SC))of PVDF-based *** addition to high operational stability,mechanical robustness,and long-term reliability,the developed TENG consisting of PVDF incorporated with Co-MOF(Co-MOF@PVDF)achieved a VOC of 194 V and an I_(SC)of 18.8μ***,the feasibility of self-powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system(GPS)*** local position of the user in real-time through GPS was displayed on a mobile interface,powered by the battery charged through friction-induced electricity generation.

关键词： bar printing phase transition polyvinylidene fluoride incorporated with cobalt-based metal-organic framework self-powered mobile electronics wearable triboelectric nanogenerators

DYNAMIC PROPERTIES OF AL-ALLOY FOAM BEAM DAMAGED BY COMPRESSIVE FATIGUE

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Acta Mechanica Solida Sinica 2008年第3期21卷 241-246页

作者： Sung-Gaun kim Ilhyun kim Amkee kim Seung-joon kim Junhong Park Division of Mechanical and Automotive Engineering Kongju National University 275 Budae-dongCheonan Chungnam 330-717 Korea Department of Mechanical Engineering Hanyang University Seongdong-Gu Seoul 133-791 Korea

The permanent residual strain in aluminum （Al） alloy foams induced by compressive fatigue gradually increases with the increasing number of loading cycles. Consequently, the progressive shortening of Al-alloy foam degrades the dynamic material performance by the failure and ratcheting of multi-cells in the foam. In this paper, the dynamic properties of Al-alloy foams damaged by compressive fatigue were studied. The beam specimens with various residual strains were made by cyclic compression-compression stress. The dynamic bending modulus and loss factor were evaluated by using a beam transfer function method. As a result, the dynamic bending stiffness of Al-alloy foam turned out to be decreased due to damage while the loss factor was improved because of the increasing energy dissipation of such factors as cracked cell walls formed during the shortening process of the foam. The loss factor shows a manifest dependence on the fatigue residual strain.

关键词： Aluminum foam fatigue dynamic stiffness loss factor

Emission wavelength selection via anomalous polarized fluorescence in ZnO-C nanowires

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Nano Research 2024年第5期17卷 4489-4497页

作者： joon Kiat Kang kim Yong Lim Chorng Haur Sow Department of Physics National University of SingaporeSingapore 117542Singapore

Defect fluorescence from high aspect ratio semiconductor nanowires typically displays a weak polarization parallel to the nanowire’s long axis due to dielectric mismatch in high aspect ratio ***,anomalous 2.2 eV defect fluorescence distinctly polarized perpendicular to the nanowire is observed and measured from carbon-incorporated zinc oxide *** observations are significant because polarized defect emissions with consistent polarization on a mesoscopic scale are *** a systematic study and comparison of experimental results with density functional theory calculations,an oriented defect complex comprising carbon substituting on an oxygen site and an oxygen vacancy(CO-VO)is deduced to be responsible for the anomalous yellow fluorescence,demonstrating a method for relating atomic-scale defect geometry to mesoscopic *** anomalous emission can appear in both green-and red-fluorescing nanowires grown with different carbon concentrations,verifying the independence and uniqueness of the 2.2 eV *** allows for polarization-dependent emission wavelength selection from a single nanowire.

关键词： anomalous polarization defects fluorescence zinc oxide carbon

Adhesion and Suction Functions of the Tip Region of a Nectar-drinking Butterfly Proboscis

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Journal of Bionic Engineering 2017年第4期14卷 600-606页

作者： Seung Chul Lee Jun Ho kim Sang joon Lee Department of Mechanical Engineering Pohang University of Science and Technology Pohang 37673 Gyeongbuk Republic of Korea Center for Biofluid and Biomimic Research Pohang University of Science and Technology Pohang 37673 Gyeongbuk Republic of Korea

In this study, we investigated the dynamic functions of the tip region of the butterfly proboscis through which liquid is sucked during liquid feeding. The microstructures and flow patterns in the tip region of the proboscis were in vivo analyzed. The tip region can be divided into two functional sections： namely adhesion and suction sections. The liquid adheres to the adhesion section during liquid suction. Although the tip region has numerous slits connected to food canal of the proboscis, liquid is mainly sucked through the suction section, which section is submerged in the fluid pulled by the adhesion section and then successfully imbibes liquid. To check the dynamic functions of the tip region, we fabricated a suction tip model having adhesion and suction parts. The in vitro model experiments show that the hydrophilicity of the adhesion part and the existence of the suction inlet improve the liquid uptake driven by a suction pump. This study may provide insights for the biomimetic design of nectar-feeding butterflies.

关键词： butterfly proboscis nectar-feeding strategy suction

Dynamic observation of dendrite growth on lithium metal anode during battery charging/discharging cycles

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npj Computational Materials 2022年第1期8卷 960-972页

作者： Hae Gon Lee Se Young kim joon Sang Lee Next Generation Battery Research Center Korea Electrotechnology Research Institute(KERI)12Jeongiui-gilSeongsan-guChangwon-siGyeongsangnam-do51543Republic of Korea Department of Mechanical Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Republic of Korea

Lithium metal is considered one of the most promising anode materials for application in next-generation ***,despite decades of research,practical application of lithium metal batteries has not yet been achieved because the fundamental interfacial mechanism of lithium dendrite growth is not yet fully *** this study,a series of reactive molecular dynamics (MD) simulations was performed to investigate the electrochemical dynamic reactions at the electrode/electrolyte *** allows quantitative characterization of morphological phenomena and real-time interfacial visualization of the dynamic growth of dead lithium and dendrites during repeated *** computational protocol was utilized to investigate the dendrite mitigation mechanism when an electrolyte additive (hydrogen fluoride) is dissolved in an organic ethylene carbonate (EC) electrolyte *** was confirmed that beneficial decomposition reactions between electrolyte components form a protective film on the anode surface,suppressing large interphase volume changes and unnecessary degradation reactions.

关键词： battery lithium electrolyte

Ultra-low concentration of total organic carbon in ultrapure water using ion-exchange resin embedding silanized magnetic nanoparticles

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Journal of Environmental Sciences 2020年第6期32卷 11-17页

作者： Jung joon Lee Jihyeon Park Bo-Hyun kim Sunjong Lee Department of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419South Korea Korea Institute of Industrial Technology 89 Yangdaegiro-gilIpjang-myeonCheonan-si 31056South Korea

Regeneration of pure water is an important issue not only for the healthy life but also for the fine control of precise processes in various *** important issue in ultrahigh purified water is to reduce the amount of total organic carbon(TOC).Herein,we introduce a new approach to reduce the TOC using the surface silanized nanoparticles,in which the magnetic nanoparticles(mNPs)are silanized and then complexed with ion exchange resin(IER)*** Fe3O4 mNPs are surface modified by using high concentrated vinyltrimethoxysilane(VTMS)and then adhered on the surface of IER *** surface modified mNPs have a thick-shell of polysiloxane layer varying from 5 to 22 nm depending on the amount of VTMS used,which leads the significant increase of specific surface *** IER beads embedding VTMS-silanized mNPs achieves about 7μg/L of the TOC level in ultrapure water system,which is two orders less than 228μg/L of the feeding water and one order less than 96μg/L from the system using pristine IER *** result is mainly attributed to the polysiloxane layer forming broccoli-like surface structure and some part by the vinyl group of VTMS exposed to the amines in the water.

关键词： Total organic carbon Ultrapure water Magnetic nanoparticle Ion-exchange resin Hybrid structure

X region mutations of hepatitis B virus related to clinical severity

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World Journal of Gastroenterology 2016年第24期22卷 5467-5478页

作者： Hong kim Seoung-Ae Lee Bum-joon kim Department of Biomedical Sciences Microbiology and Immunology Liver Research Institute and Cancer Research Institute College of Medicine Seoul National University

Chronic hepatitis B virus (HBV) infection remains a major health problem, with more than 240 million people chronically infected worldwide and potentially 650000 deaths per year due to advanced liver diseases including liver cirrhosis and hepatocellular carcinoma (HCC). HBV-X protein (HBx) contributes to the biology and pathogenesis of HBV via stimulating virus replication or altering host gene expression related to HCC. The HBV X region contains only 465 bp encoding the 16.5 kDa HBx protein, which also contains several critical cis-elements such as enhancer II, the core promoter and the microRNA-binding region. Thus, mutations in this region may affect not only the HBx open reading frame but also the overlapped cis-elements. Recently, several types of HBx mutations significantly associated with clinical severity have been described, although the functional mechanism in most of these cases remains unsolved. This review article will mainly focus on the HBx mutations proven to be significantly related to clinical severity via epidemiological studies.

关键词： Hepatitis B virus infection Hepatitis B virus-X protein mutation Hepatocellular carcinoma Clinical severity

Ballistic limit velocity of small caliber projectiles against SS400 steel plates:Live fire experiments and empirical models

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Defence Technology（防务技术） 2024年第11期41卷 22-34页

作者： Jong-Hwan kim Seungwon Baik Jirui Fu joon-Hyuk Park Mechanical&Systems Engineering Korea Military Academy574 Hwarang-roNowon-guSeoul17977South Korea Mechanical and Aerospace Engineering University of Central Florida4000 Central Florida BlvdOrlandoFL 32816United States

This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.

关键词： Live fire ballistic experiment SS400 Ballistic limit velocity Small caliber projectile

Diagnostic value of PIVKA-Ⅱ and alpha-fetoprotein in hepatitis B virus-associated hepatocellular carcinoma

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World Journal of Gastroenterology 2015年第13期21卷 3928-3935页

作者： Seung In Seo Hyoung Su kim Won Jin kim Woon Geon Shin Doo Jin kim Kyung Ho kim myoung Kuk Jang Jin Heon Lee Joo Seop kim Hak Yang kim Dong joon kim Myung Seok Lee Choong Kee Park Department of Internal Medicine Hallym University Medical CenterSeoul 134-701South Korea Digestive Disease Center Hallym University Medical CenterSeoul 134-701South Korea Department of Surgery Hallym University Medical CenterSeoul 134-701South Korea

AIM: To determine the cutoff values and to compare the diagnostic role of alpha-fetoprotein(AFP) and prothrombin induced by vitamin K absence-Ⅱ(PIVKA-Ⅱ) in chronic hepatitis B(CHB).METHODS: A total of 1255 patients with CHB, including 157 patients with hepatocellular carcinoma(HCC), 879 with non-cirrhotic CHB and 219 with cirrhosis without HCC, were retrospectively enrolled. The areas under the receiver operating characteristic(AUROC) curves of PIVKA-Ⅱ, AFP and their combination were calculated and ***: The optimal cutoff values for PIVKA-Ⅱ and AFP were 40 m AU/m L and 10 ng/m L, respectively, for the differentiation of HCC from nonmalignant CHB. The sensitivity and specificity were 73.9% and 89.7%, respectively, for PIVKA-Ⅱ and 67.5% and 90.3% for AFP, respectively. The AUROC curves of both PIVKA-Ⅱ and AFP were not significantly different(0.854 vs 0.853, P = 0.965) for the differentiation of HCC from nonmalignant CHB, whereas the AUROC of PIVKA-Ⅱ was significantly better than that of AFP in patients with cirrhosis(0.870 vs 0.812, P = 0.042). When PIVKA-Ⅱ and AFP were combined, the diagnostic power improved significantly compared to either AFP or PIVKA-Ⅱ alone for the differentiation of HCC from nonmalignant CHB(P < 0.05), especially when cirrhosis was present(P < 0.05).CONCLUSION: Serum PIVKA-Ⅱ might be a better tumor marker than AFP, and its combination with AFP may enhance the early detection of HCC in patients with CHB.

关键词： Hepatitis B virus Hepatocellular carcinoma Alpha-f

Counter-balancing effects of Si on C partitioning and stacking fault energy of austenite in 10Mn quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第3期98卷 248-257页

作者： Dong Hwi kim Jee-Hyun Kang Hojun Gwon Joo Hyun Ryu Sung-joon kim Graduate Institute for Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Materials Science and Engineering Institute of Materials TechnologyYeungnam UniversityGyeongsan 38541Republic of Korea POSCO Technical Research Laboratories POSCOGwangyang 57807Republic of Korea

Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize *** 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free ***,the suppression of carbide formation promoted C partitioning into austenite as ***,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of *** partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility *** was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the *** resulting strengthening effect compensated for the softening caused by martensite ***,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.

关键词： Steels Q&P steel Silicon Austenite stability Tensile deformation Stacking fault energy Medium Mn steel