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Spindle-like FeySs/N-doped carbon nanohybrids for high-performance sodium ion battery anodes

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Nano Research 2019年第3期12卷 695-700页

作者： Aihua Jin Mi-ju Kim Kug-seung lee seung-Ho Yu Yung-Eun Sung Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 08826 Republic of Korea School cf Chemical and Biological Engineering Seoul National University Seoul 08826 Republic cf Korea Beamline Department Pohang Accelerator Laboratory (PAL) Pohang 790-784 Republic of Korea Department of Chemistry and Chemical Biology Cornell University Ithaca New York 14853 USA

Iron sulfides have bee n con sidered as one of the most promising can didates for sodium ion battery anode materials due to their high theoretical capacity and low cost. I n this work, spin dle-like Fe7S8 with n itroge rvdoped carb on (FeiS/N-C) nano hybrids are successfully syn thesized via a solvothermal method by sulfidation iron-based metal organic framework (FeMOF). As sodium ion battery an odes, FeySs/N-C nano hybrids exhibit high reversible capacity of 450.8 mAh g-1 at 200 mA·g^-1, and 406.7 mAh·g^-1 at 500 mA·g^-1 even after 500 cycles. They also show excellent rate properties and delivering the capacity of 327.8 mAh·g^-1 at a very high current density of 3.2 A·g^-1. These outstanding electrochemical performa nces can be attributed to the unique structure of Fe7S8/ N-C nan ohybrids. The nano scale dime nsion in their size can be ben eficial for facile ion and electro n tran sports. Furthermore, the stable n itroge n doped carb on frameworks can also improve electrical conductivity and relieve the problems related to volume expansion. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy analyses have been performed to study reactions occurred in spindle-like FeySs/N-C nanohybrid electrode at both bulk and surface.

关键词： sodium ion batteries iron sulfides metal organic frameworks X-ray absorption spectroscopy X-ray photoelectron spectroscopy

Numerical evaluation of buckling behavior in space structure considering geometrical parameters with joint rigidity

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Journal of Central South University 2014年第3期21卷 1115-1124页

作者： Su-Deok Shon Kyung-ju Hwang seung-Jae lee School of Architectural Engineering Korea University of Technology and Education School of Architecture University of Seoul

The buckling behavior of single layer space structure is very sensitive. The joint rigidity, moreover, is one of the main factors of stability which may determine the entire failure behavior. Thus, the reasonable stiffness of joint system, which is neither total pin assumption nor perfect fix condition, is very important to apply to the real single layer space one. Therefore, the purpose of this work was to investigate the buckling behavior of single layer space structure, using the development of the upgraded stiffness matrix for the joint rigidity. To derive tangential stiffness matrix, a displacement function was assumed using translational and rotational displacement at the node. The geometrical nonlinear analysis was simulated not only with perfect model but also with imperfect one. As a result, the one and two free nodal numerical models were investigated using derived stiffness matrix. It was figured out that the buckling load increases in proportion to joint rigidity with rise-span ratio. The stability of numerical model is very sensitive with the initial imperfection, responding of bifurcation in the structure.

关键词： space frame geometric nonlinearity snap-through bifurcation initial imperfection joint rigidity

Effect of silicon carbide-based iron catalyst on reactor optimization for non-oxidative direct conversion of methane

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Journal of Energy Chemistry 2023年第6期81卷 519-532,I0012页

作者： Eun-hae Sim Sung Woo lee Jin ju lee seung ju Han jung Ho Shin Gracia lee Sungrok Ko Kwan-Young lee Yong Tae Kim C1 Gas&Carbon Convergent Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea Department of Chemical and Biological Engineering Korea University145 Anam-roSeoul 02841Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeoul 03722Republic of Korea Chemical Data-Driven Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea Prospective Tech.Exploring Section Basic Chemical R&D centerLottechemical Corp.Daejeon 34059Republic of Korea Department of Advanced Materials and Chemical Engineering University of Science and Technology(UST)Gajeong-dongYuseongDaejeon 34113Republic of Korea

The conversion of methane to olefins,aromatics,and hydrogen(MTOAH)can be used to stably obtain hydrocarbons when the effect of the catalytic surface is optimized from the reaction engineering *** this study,Fe/Si C catalysts were packed into a quartz tube *** catalytic surfaces of Si C and the impregnated Fe species decreased the apparent activation energies(E_a)of methane consumption in the blank reactor between 965 and 1020℃.Consequently,the hydrocarbon yield increased by 2.4times at 1020℃.Based on the model reactions of ethane,ethylene,and acetylene mixed with hydrogen in the range of 500-1020℃,an excess amount of Fe in the reactor favored the C-C coupling reaction over the selective hydrogenation of acetylene;consequently,coke formation was favored over the hydrogenation *** gas-phase reactions and catalyst properties were optimized to increase hydrocarbon yields while reducing coke *** 0.2Fe catalyst-packed reactor(0.26 wt%Fe)resulted in a hydrocarbon yield of 7.1%and a coke selectivity ofjusted to be≥*** on these findings,the facile approach of decoupling the reaction zone between the catalyst surface and the gas-phase reaction can provide insights into catalytic reactor design,thereby facilitating the scale-up from the laboratory to the commercial scale.

关键词： Non-oxidative methane conversion Ethylene Aromatic Methane pyrolysis Fe/SiC Coke resistance Catalytic reactor

Two-Terminal Lithium-Mediated Artificial Synapses with Enhanced Weight Modulation for Feasible Hardware Neural Networks

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Nano-Micro Letters 2023年第5期15卷 236-253页

作者： Ji Hyun Baek Kyung ju Kwak seung ju Kim Jaehyun Kim Jae Young Kim In Hyuk Im Sunyoung lee Kisuk Kang Ho Won Jang Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Republic of Korea Advanced Institute of Convergence Technology Seoul National UniversitySuwon 16229Korea

Recently,artificial synapses involving an electrochemical reaction of Li-ion have been attributed to have remarkable synaptic ***-terminal synaptic transistors utilizing Li-ion intercalation exhibits reliable synaptic characteristics by exploiting the advantage of nondistributed weight updates owing to stable ion ***,the three-terminal configurations with large and complex structures impede the crossbar array implementation required for hardware neuromorphic ***,achieving adequate synaptic performances through effective Li-ion intercalation in vertical two-terminal synaptic devices for array integration remains ***,two-terminal Au/LixCoO_(2)/Pt artificial synapses are proposed with the potential for practical implementation of hardware neural *** Au/LixCoO_(2)/Pt devices demonstrated extraordinary neuromorphic behaviors based on a progressive dearth of Li in LixCoO_(2)*** intercalation and deintercalation of Li-ion inside the films are precisely controlled over the weight control spike,resulting in improved weight control *** types of synaptic plasticity were imitated and assessed in terms of key factors such as nonlinearity,symmetricity,and dynamic ***,the LixCoO_(2)-based neuromorphic system outperformed three-terminal synaptic transistors in simulations of convolutional neural networks and multilayer perceptrons due to the high linearity and low programming *** impressive performances suggest the vertical two-terminal Au/LixCoO_(2)/Pt artificial synapses as promising candidates for hardware neural networks.

关键词： Artificial synapse Neuromorphic Li-based Two-terminal Synaptic plasticity

Avoiding heating interference and guided thermal conduction in stretchable devices using thermal conductive composite islands

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Nano Research 2021年第9期14卷 3253-3259页

作者： seung Ji Kang Haeleen Hong Chanho Jeong ju seung lee Hyewon Ryu Jae-hun Yang Jong Uk Kim Yiel Jae Shin Tae-il Kim School of Chemical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Department of Biomedical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Biomedical Institute for Convergence(BICS) Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea

The miniaturization and high integration of devices demand significant thermal management *** technologies for the thermal management of electronics show some limitations in the case of multiple chip arrays.A device in multiple chip array is affected by heat from adjacent devices,along with thermal conductive *** address this problem,we present a nano composite of aligned boron nitride(BN)nanosheet islands with porous polydimethylsiloxane(PDMS)foam to have mechanical stability and non-thermal *** islands of tetrahedrally-structured BN in the composite have a high thermal conductivity of 1.219 W·m^(-1)·K^(-1) in the through-plane direction(11.234W·m^(-1)·K^(-1)in the in-plane direction)with 16 wt.%loading of *** the other hand,porous PDMS foam has a low thermal conductivity of 0.0328W·m^(-1)·K^(-1) in the through-plane direction at 70%*** pathways are then formed only in the structured BN islands of the *** porous PDMS foam can be applied as a thermal barrier between structured BN islands to inhibit thermal interference in multiple device ***,this composite can maintain selective thermal dissipation performance with 70%tensile *** beauty of the work is that it could have guided heat dissipation by assembling of multiple layers which have high vertical thermal conductive islands,while inhibiting thermal *** selective heat dissipating composite can be applied as a heatsink for multiple chip arrays electronics.

关键词： selective thermal conduction non-thermal interference thermal conductive composite island stretchable electronics structured boron nitride nanosheet(s-BN) porous polydimethylsiloxane(p-PDMS)

Effects of Chairside Polishing and Brushing on SurfaceRoughness of Acrylic Denture Base Resins

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Journal of Wuhan University of Technology(Materials Science) 2009年第1期24卷 100-105页

作者： seung-Kyun Kim ju-Mi Park Min-Ho lee Jae-Youn jung Shipu Li Xinyu Wang Department of Prosthodontics and Institute of Oral Bioscience School of Dentistry Chonbuk National University Jeonju Republic of Korea Department of Dental Biomaterials and Institute of Oral Bioscience School of Dentistry Chonbuk National University Jeonju Republic of Korea Division of Mechanical & Aerospace System Engineering and RCIT Chonbuk National University Jeonju Republic of Korea Biomedical Materials and Engineering Research Center Wuhan University of Technology Wuhan 430070 China

The effects of 3 chairside polishing kits and mechanical brushing on the surface roughness of 3 different acrylic denture base resins were compared. Acrylic denture base resins （auto-polymerizing, heat-polymerizing, injected heat-polymerizing resins） were examined after a tungsten carbide bur, and after chairside polishing using 3 polishing kits and pumice. The specimens were subjected to mechanical brushing using a wear tester to simulate 30 000 strokes of brushing. The surface roughness of the acrylic denture base resin specimens was measured using a contact pro-filometer. After the test, the random polished acrylic resins were evaluated by scanning electron mi-croscopy （SEM） and atomic force microscopy （AFM）. Acrylic denture base resins polished using the 3 types of polishing kits had a smoother surface than those finished with the tungsten carbide bur （p〈0.05）. The surface of the resin polished by a TC cutter exceeded the Ra of 0.2 μm （p〈0.05）. The auto-polymerizing resin showed a significantly higher surface roughness than the heat-polymerizing resin and injected heat-polymerizing resin （p〉0.05）. In the case of polishing step wise, there was almost no change in surface roughness after brushing （p〉0.05）.

关键词： acrylic denture base resin polishing brushing surface roughness

The Machine Learning Ensemble for Analyzing Internet of Things Networks:Botnet Detection and Device Identification

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Computer Modeling in Engineering & Sciences 2024年第11期141卷 1495-1518页

作者： seung-ju Han Seong-Su Yoon Ieck-Chae Euom System Security Research Center Chonnam National UniversityGwangju61186Republic of Korea

The rapid proliferation of Internet of Things(IoT)technology has facilitated automation across various ***,this advancement has also resulted in a notable surge in cyberattacks,notably *** a result,research on network analysis has become *** learning-based techniques for network analysis provide a more extensive and adaptable approach in comparison to traditional rule-based *** this paper,we propose a framework for analyzing communications between IoT devices using supervised learning and ensemble techniques and present experimental results that validate the efficacy of the proposed *** results indicate that using the proposed ensemble techniques improves accuracy by up to 1.7%compared to single-algorithm *** results also suggest that the proposed framework can flexibly adapt to general IoT network analysis *** existing frameworks,which only exhibit high performance in specific situations,the proposed framework can serve as a fundamental approach for addressing a wide range of issues.

关键词： Internet of Things machine learning traffic analysis botnet detection device identification

Successful recanalization of acute superior mesenteric artery thrombotic occlusion with primary aspiration thrombectomy

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World Journal of Gastroenterology 2010年第32期16卷 4112-4114页

作者： Hye Jin Yang Young Kwon Cho Yun ju Jo Yoon Young jung seung A Choi Suk Hoon lee Department of Radiology Eulji General HospitalEulji UniversitySeoul 139-711South Korea Department of Internal Medicine Eulji General HospitalEulji UniversitySeoul 139-711South Korea

Prompt revascularization of the superior mesenteric artery(SMA) thrombotic occlusion can prevent intestinal infarction and decrease necrosis of the bowel ***,we describe two cases who underwent successful endovascular recanalization for acute SMA thrombosis using a primary aspiration thrombectomy because of possible consequent laparotomy for survey of bowel *** two patients had dramatic pain reliefimmediately after the procedure and remained symptomfree during the follow-up period.

关键词： Superior mesenteric artery Thrombosis Aspiration thrombectomy

Comparative Study of Visual and Instrumental Analyses of Shade Selection

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Journal of Wuhan University of Technology(Materials Science) 2010年第1期25卷 62-67页

作者： Jee-Ha Choi ju-Mi Park seung-Geun Ahn Kwang-Yeob Song Min-Ho lee Jae-Youn jung Xinyu Wang Department of Prosthodontics and Institute of Oral Bioscience School of Dentistry Chonbuk National University Jeonju Republic of Korea Department of Dental Biomaterials and Institute of Oral Bioscience School of Dentistry Chonbuk National University Jeonju Republic of Korea Division of Mechanical & Aerospace System Engineering and RCIT Chonbuk National University Jeonju Republic of Korea Biomedical Materials and Engineering Research Center Wuhan University of Technology Wuhan 430070 China

The difference between visual and instrumental analyses of a shade selection on natural teeth was investigated. With visual analysis, five prosthodontist examined the middle third of the unrestored maxillary right central incisor of a patient using VITAPEN classical and Vita Toothguide 3D-MASTER tooth shade guide. In instrumental analysis, one prosthodontist examined the same teeth using a spectrophotometer （ShadepilotTM, Degudent, Hanau-Wolfgang, Germany, software 2.40）. Overall, instrumental analysis is more accurate and reproducible than a visual assessment. However, the difference is clinically acceptable.

关键词： shade selection visual analysis instrumental analysis spectrophotometer