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Effect of thixoextrusion parameters on mechanical properties of 7003 Aluminum wrought alloy

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Rare Metals 2006年第Z2期25卷 124-128页

作者： YOON young-Ok JANG Dong-In JO Hyung-Ho kim young-Jig kim Shae K Department of Advanced Material Engineering Sungkyunkwan University 300 Chunchun-dong Jangan-gu Suwon Gyunggi-do 440-746 KoreaAdvanced Material Center Korea Institute of Industrial Technology 7-47 Songdo-dong Yeonsu-gu Incheon 406-840 Korea Advanced Material Center Korea Institute of Industrial Technology 7-47 Songdo-dong Yeonsu-gu Incheon 406-840 Korea Department of Advanced Material Engineering Sungkyunkwan University 300 Chunchun-dong Jangan-gu Suwon Gyunggi-do 440-746 Korea

The processing of high strength Al wrought alloys does lead either to restrictions for geometrical complexity or to high production costs due to low productivity and multiple-step processes. Thixoextrusion process to overcome these difficulties has been under investigation. In the present study, the effect of thixoextrusion parameters was investigated on mechanical properties of 7003 Al wrought alloy. The maximum extrusion pressure of the thixoextrusion process is three times lower than that of the hot extrusion process. The elongated grains which have the axisymmetry with extrusion direction are generally observed during hot extrusion process, while the microstructures of the thixoextruded are isotropic. The tensile and yield strengthes of the thixoextruded bar are lower than those of the hot extruded bar, while the elongation value of the thixoextruded bar is higher than that of the hot extruded bar.

关键词： thixoextrusion isotropy 7003 Al wrought alloy

Cryptogenic organizing pneumonia associated with pregnancy:A case report

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World Journal of Clinical Cases 2022年第6期10卷 1946-1951页

作者： young Joo Lee young Sun kim Department of Obstetrics and Gynecology Kyung Hee University Medical CenterSeoul 02447South Korea

BACKGROUND Cryptogenic organizing pneumonia(COP),formerly known as bronchiolitis obliterans organizing pneumonia,is an extremely rare disease in *** this case,we report on COP diagnosed in recurrent pneumonia that does not respond to antibiotics in pregnant *** SUMMARY A 35-year-old woman with no prior lung disease presented with concerns of chest pain with cough,sputum,dyspnea,and mild fever at 11 wk’*** was diagnosed with community-acquired pneumonia and treated with antibiotics;her symptoms improved *** weeks after discharge,she was readmitted with aggravated *** computed tomography demonstrated multifocal patchy airspace consolidation and ground-glass opacities at the basal segments of the right lower lobe,at the lateral basal segment of the lower lobe,and at the lingular segment of the left upper *** lavage revealed an increased lymphocyte count and a decreased CD4/CD8 ***(0.5 mg/kg/d)was administered for 10 d after the second *** improved after 3 d of steroid treatment and other symptoms improved on the 5th day of steroid ***-delivery transbronchial lung biopsy further revealed the presence of granulation tissue with fibroblasts in smallbronchiole *** This case suggests that it is important to differentiate COP from atypical pneumonia in the deteriorated condition despite antibiotic treatment.

关键词： Antibiotics Bronchiolitis obliterans organizing pneumonia Corticosteroid Cryptogenic organizing pneumonia Pregnancy Case report

Engineering Geometric Electrodes for Electric Field-Enhanced High-Performance Flexible In-Plane Micro-Supercapacitors

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Energy & Environmental Materials 2023年第4期6卷 114-120页

作者： Jihong kim Sung Min Wi Jong-Guk Ahn Sangjun Son Hee young Lim Yeonsu Park Hye Ji Eun Jong bae Park Hyunseob Lim Sangyeon Pak A-Rang Jang young-Woo Lee Department of Energy Engineering Soonchunhyang UniversityAsan 31538Korea Department of Chemistry Gwangju Institute of Science and TechnologyGwangju 61005Korea Jeonju Centre Korea Basic Science InstituteJeonju 54907Korea Prof.S.Pak School of Electronic and Electrical Engineering Hongik UniversitySeoul 04066Korea Division of Electrical Electronic and Control EngineeringKongju National UniversityCheonan 31080Korea

In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable *** implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates,ions must be readily transported to electrodes for achieving high power ***,we show large enhancement in electrochemical properties of flexible,inplane micro-supercapacitor using sharp-edged interdigitated electrode design,which was simply fabricated through direct laser scribing *** sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode,significantly enhancing the energy storage performance of *** electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L^(−1)and the excellent cyclability with capacitive retention of 95.4%after 20000 *** further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability,mechanical stability,and air *** results present an important pathway for designing electrodes in various energy storage devices.

关键词： electric field enhancement flexible energy storage device microsupercapacitors sharp electrodes

Fatigue-Induced Micro-damage Characterization of Austenitic Stainless Steel 316 Using Innovative Nonlinear Acoustics

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Chinese Physics Letters 2012年第6期29卷 82-85页

作者： Chung-Seok kim Kyung-young JHANG Automotive Engineering Hanyang UniversityHangdang-dongSeongdong-guSeoul133-791South Korea Mechanical Engineering Hanyang UniversityHangdang-dongSeongdong-guSeoul133-791South Korea

We present innovative nonlinear acoustics for characterizing fatigue-induced micro-damage of austenitic stainless steel 316 subjected to high-cycle *** fatigue-driven deformations are accumulated at several positions near the middle of hourglass-shaped specimens.A bell-shaped curve of acoustic nonlinearity as a function of position is observed,and the variation in acoustic nonlinearity is attributed to the evolution of a lattice defect (dislocation) and stress-induced martensite based on transmission electron microscopy (TEM) *** oblique incidence technique using a longitudinal waveform is a potentially viable method for characterizing the high-cycle fatigue deformation of austenitic stainless steel 316 alloys.

关键词： fatigue steel martensite

Analysis of temperature distribution in PV-integrated electrochemical flow cells

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Materials Futures 2023年第4期2卷 137-144页

作者： Dorian Santander Shaun Whitley Jungmyung kim Dowon bae Institute of Mechanical Process and Energy Engineering(IMPEE)School of Engineering and Physical SciencesHeriot-Watt UniversityEdinburgh EH144ASUnited Kingdom Ecole nationale supérieure d’électricitéet de mécanique de Nancy Vandoeuvre-lès-NancyFrance AECOM EdinburghEH35DAUnitedKingdom

Photovoltaic(PV)-integrated flow cells for electrochemical energy conversion and storage underwent a huge *** advantages of this type of integrated flow cell system include the simultaneous storage of solar energy into chemicals that can be readily utilized for generating ***,most studies overlook the practical challenges arising from the inherent heat exposure and consequent overheating of the reactor under the *** work aims to predict the temperature profiles across PV-integrated electrochemical flow cells under light exposure conditions by introducing a computational fluid dynamics–based ***,we discuss the effects of the flow channel block architecture on the temperature profile to provide insights and guidelines for the effective remedy of overheating.

关键词： solar redox flow battery CFD redox flow cell energy conversion temperature profile

Sandwich-type ordered mesoporous carbon/graphene nanocomposites derived from ionic liquid

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Nano Research 2016年第9期9卷 2696-2706页

作者： Ho Seok kim young Hwan kim Kwang Chul Roh Kwang-Bum kim Lab of Energy Storage Materials Department of Material Science & EngineeringYonsei UniversitySeou1120749Republic of Korea Energy & Environmental Division Korea Institute of Ceramic Engineering & TechnologyJinju 52851Republic of Korea

Sandwich-type ordered mesoporous carbon/graphene nanocomposites were successfully synthesized using 2D ordered mesoporous silica/graphene nanocomposites as the hard template and an ionic liquid as a N-rich carbon source. We used an ionic liquid of 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide containing nitrile groups (–CN) in the cation and anion as a carbon precursor for the preparation of the nanocomposites. Nitriles do not decompose under thermal treatment in an inert gas atmosphere, but leave significant amounts of N-rich carbon materials. The nanocomposites had a large surface area (1,316 m2·g–1), an average pore diameter of 5.9 nm, and high electrical conductivity. The nanocomposite electrode showed a high specific capacitance of 190 F·g–1at 0.5 A·g–1in 1 M TEABF4/AN electrolyte and a good rate capability between 0 and 2.7 V for supercapacitor (or ultracapacitor) applications. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： ionic liquid-derived carbon ordered mesoporous carbon/graphene nanocomposite 2D graphene nanocomposite supercapacitor

Grain size dependence of flow stress in ECAPed Ti with constant texture

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中国有色金属学会会刊：英文版 2012年第S3期22卷 673-677页

作者： Chang-young HYUN Ho-Kyung kim Department of Materials Science and Engineering Seoul National University of Science and Technology Department of Automotive Engineering Seoul National University of Science and Technology

The effect of grain size on the flow stress in an ECAPed Ti with a constant texture was investigated,assuming that 2,4,5 and 6 passes microstructures have a similar *** average size of recrystallized grains decreased to 0.5 μm,0.4 μm,and 0.3 μm with respect to the ECAP pass number of 2,4,and 6,*** ultimate tensile strength (UTS) and yield strength (YS) increase with an increase in the number of *** UTS and YS of the 6 passes ECAPed sample were found to be 740.2 MPa and 580.3 MPa,*** equation for the flow stress of an ECAPed Ti with a constant texture as a function of the strain and grain size was derived for the ECAPed *** following equation was finally obtained:σ(ε)=103.9+1825ε-9.6ε1/2·d-1/2+8.3d-1/2.

关键词： Ti mechanical properties grain size flow stress equal channel angular pressing

The Role of Relative Spinal Motion during Feline Galloping for Speed Performance

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Journal of Bionic Engineering 2014年第4期11卷 517-528页

作者： young Kook kim Jongwon Park Byungho Yoon Kyung-Soo kim Soohyun kim Robotics Program Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Republic of Korea Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Republic of Korea

Felines use their spinal column to increase their running speed at rapid locomotion performance. However, its motion profile behavior during fast gait locomotion has little attention. The goal of this study is to examine the relative spinal motion profile during two different galloping gait speeds. To understand this dynamic behavior trend, a dynamic motion of the feline animal （Felis catus domestica） was measured and analyzed by motion capture devices. Based on the experiments at two different galloping gaits, we observed a significant increase in speed （from 3.2 m.s-1 to 4.33 m.s-1） during the relative motion profile synchronization between the spinal （range： 118.86~ to 168.00~） and pelvic segments （range： 46.35~ to 91.13~） during the hindlimb stance phase （time interval： 0.495 s to 0.600 s）. Based on this discovery, the relative angular speed profile was applied to understand the possibility that the role of the relative motion match during high speed locomotion generates bigger ground reaction force.

关键词： feline galloping galloping gait pattern relative spinal motion speed performance phase match

Acoustic Nonlinearity of a Laser-Generated Surface Wave in a Plastically Deformed Aluminum Alloy

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Chinese Physics Letters 2012年第12期29卷 39-43页

作者： kim Chung-Seok JHANG Kyung-young Metallurgy and Materials Engineering Chosun UniversitySeosuk-dongGwangju501-759South Korea Mechanical Engineering Hanyang UniversityHangdang-dongSeongdong-guSeoul133-791South Korea

The acoustic nonlinearity of surface waves is studied to evaluate plastic deformation in aluminum alloys.A narrow-band surface wave is successfully generated by a pulsed Nd-YAG laser system consisting of a beam expander and a slit *** degrees of tensile deformation are induced by interrupting the tensile tests so as to obtain aluminum specimens with different degrees of plastic *** normalized acoustic nonlinearity increases as a function of tensile *** experimental results show that the acoustic nonlinearity of a laser-generated surface wave has a good correlation with the level of tensile deformation and has a potential to evaluate microdamage induced by dislocation microplasticity.

关键词： deformation nonlinearity Deform