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Collapse behavior evaluation of hybrid thin-walled member by stacking condition

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 135-140页

作者： Kil-Sung LEE Hyeon-Kyeong SEO Yong-June YANG Woo-Chae HWANG kwang-hee im In-Young YANG R&D Center Dacc LTD. 948-13 Dunsan-ri Bongdong-eup Wanju-gun Jeonbuk 565-902 Korea Departments of Advanced Parts and Materials Engineering Graduate School Chosun University Department of Automotive Engineering Woosuk University Departments of Mechanical Design Engineering Chosun University

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, the energy absorbing members should absorb collision energy sufficiently but for the environmentally-friendly aspect, the vehicle structure must be light weight in order to improve the fuel efficiency and reduce the tail gas emission. Therefore, the light weight of vehicle must be achieved in a securing safety status of crash. An aluminum or carbon fiber reinforced plastics (CFRP) is representative one of the light-weight materials. Based on the respective collapse behavior of aluminum and CFRP member, the collapse behavior of hybrid thin-walled member was evaluated. The hybrid members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties, such as strength and elasticity, change with its stacking condition, the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member were tested. The collapse mode and energy absorption capability of the hybrid thin-walled member were analyzed with the change of the fiber orientation angle and interface number.

关键词： collapse behavior aluminum and CFRP hybrid thin-walled member stacking condition

Ultrasonic Approach of Rayleigh Pitch-Catch Contact Ultrasound Waves on CFRP Laminated Composites

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Journal of Materials Science & Technology 2008年第3期24卷 407-409页

作者： In-Young Yang kwang-hee im Uk Heo David K Hsu Je-Woong Park Hak-Joon Kim Sung-Jin Song School of Mechanical Eng. Chosun Univ Department of Automotive Eng. Woosuk Univers-ity Center for Nondestructive Evaluation Iowa State University Dept.of Naval Arch.and Ocean Eng. Chosun Univ School of Mechanical Eng. Sungkyunkwan University

CFRP （carbon fiber reinforced plastics） composite materials have wide applicability because of their inherent design flexibility and improved material properties. However, impacted composite structures have 50%-75% less strength than undamaged structures. In this work, a CFRP composite material was nondestructively characterized in order to ensure product quality and structural integrity of CFRP and one-sided pitch-catch technique was developed to measure impacted-damaged area by using an automated-data acquisition system in an immersion tank. A pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave under defect conditions in the composite.

关键词： impact damages C-scanner Carbon fiber reinforced plastics (CFRP) Pitchcatch mode

ULTRASONIC INFLUENCE OF POROSITY LEVEL ON CFRP COMPOSITE LAMINATES USING RAYLEIGH PROBE WAVES

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Acta Mechanica Solida Sinica 2008年第4期21卷 298-307页

作者： Je-Woong Park Do-Jung Kim kwang-hee im Sang-Kyu Park David K.Hsu Adam H.Kite Sun-Kyu Kim Kil-Sung Lee In-Young Yang Dept.of Naval Architecture and Ocean Eng. Chosun UniversityKwangju 501-759Korea Dept.of Automotive Eng. Woosuk UniversitySamrae-upWanju-kunChonbuk565-701Korea Center for Nondestructive Evaluation Iowa State UniversityAmesIowa 50011USA Division of Precision Mec.Eng. Chonbuk National UniversityJeonju 561-756Korea School of Mechanical Engineering Chosun UniversityKwangju 501-759Korea

It was found that a pitch-catch signal was more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composites （damages, fiber orientation, low level porosity, ply waviness, and cracks）. Both the strength and stiffness depend on the fiber orientation and porosity volume in the composites. The porosity content of a composite structure is critical to the strength and performance of the structure in general. The depth of the sampling volume where the pitch-catch signal came from was relatively shallow with the head- to-head miniature Rayleigh probes, but the depth can be increased by increasing the separation distance of the transmitting and receiving probes. Also, a method was utilized to determine the porosity content of a composite lay-up by processing micrograph images of the laminate. A free software package was utilized to process micrograph images of the test sample. The results from the image processing method were compared with existing data. Beam profile was characterized in unidirectional CFRP（carbon fiber reinforced plastics） using pitch-catch Rayleigh probes and the one-sided pitch-catch technique was utilized to produce C-scan images with the aid of the automatic scanner.

关键词： ply-layup orientation unidirectional CFRP beam profile pitch-catch contact mode,porosity level

Research on Cavitation Characteristics and Influencing Factors of Herringbone Gear Pump

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2917-2946页

作者： Jinlong Yang kwang-hee Lee Chul-hee Lee Department of Mechanical Engineering of Inha University Incheon22212South Korea

Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow *** is one of the main hazards that affect the regular operation of the *** on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,***,there are few cavitation studies on external herringbone gear *** addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow ***,it is urgent to study the cavitation characteristics of external herringbone gear *** with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is *** simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing *** can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be *** example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.

关键词： Herringbone gear pump cavitation rotating speed inlet pressure helix angle TwinMesh

Interfacial modulation of bifunctional electrolyte additive engineering for dendrite-free and robust lithium metal anode

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Journal of Energy Chemistry 2024年第10期97卷 120-127页

作者： Mahammad Rafi Shaik Yongmin Park Young-kwang Jung Won Bin im Division of Materials Science and Engineering Hanyang University Department of Chemical Engineering and Biotechnology University of Cambridge

Anode materials for rechargeable electric car batteries are obtained from Li-metal owing to their extremely high specific capacity and low redox ***,safety concerns related to dendrite formation on the anode surface caused by the uneven distribution of Li-ions during the discharge process interfere with the use of Li-metal in industrial *** this study,methyl vinyl sulfone（MVS）,a sulfone-based functional electrolyte additive,is used in an additive engineering strategy to control Lielectrolyte interactions and address the aforementioned *** dendrite growth may be restricted,and transition metal degradation on the surface of the cathode can be reduced by the MVS-derived functional electrolyte additive interfacial *** electrochemical performance of an ethylene carbonate/dimethyl carbonate（EC/DMC）+1 wt% MVS Li-metal anode of a Li||Li symmetric cell exhibits remarkable cycle stability,maintaining a low overvoltage for over 750 h at 1 mA cm-2,and capacity of 1 mA h ***,LiNi0.8Co0.1Mn0.1O2（NCM811） full cells with the MVS additive exhibit enhanced electrochemical stability for 250 cycles at a current density of 100 mA *** study provides an innovative approach for stabilizing the metal-electrolyte interfacial layer that may be used for practical applications in metal-based rechargeable batteries.

关键词： Bifunctional electrolyte Dendrite-free Electrolyte additive Interfacial layer Lithium rechargeable battery

Two-stage dynamic recrystallization and texture evolution in Al-7Mg alloy during hot torsion

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1900-1911页

作者： kwang Tae Son Chang hee Cho Myoung Gyun Kim Ji Woon Lee School of Mechanical Industrialand Manufacturing EngineeringOregon State UniversityCorvallis OR 97331USA Department of Materials Science Engineering Northwestern UniversityEvanston IL 60208USA Research Institute of Industrial Science and Technology(RIST) Pohang 37673Rep.of Korea Division of Advanced Materials Engineering Kongju National UniversityCheonan 31080Rep.of Korea Center for Advanced Materials and Parts of Powders Kongju National UniversityCheonan 31080Rep.of Korea

Hot torsion tests were performed on the Al-7Mg alloy at the temperature ranging from 300 to 500℃ and strain rates between 0.05 and 5 s^(-1) to explore the progressive dynamic recrystallization(DRX)and texture *** DRX behavior of the alloy manifested two distinct stages:Stage 1 at strain of≤2 and Stage 2 at strains of≥*** Stage 1,there was a slight increase in the DRXed grain fraction(X_(DRX))with predominance of discontinuous DRX(DDRX),followed by a modest change in X_(DRX) until the transition to Stage *** 2 was marked by an accelerated rate of DRX,culminating in a substantial final X_(DRX) of~*** backscattered diffraction(EBSD)analysis on a sample in Stage 2 revealed that continuous DRX(CDRX)predominantly occurred within the(121)[001]grains,whereas the(111)[110]grains underwent a geometric DRX(GDRX)evolution without a noticeable sub-grain ***,a modified Avrami’s DRX kinetics model was utilized to predict the microstructural refinement in the Al-7Mg alloy during the DRX *** this kinetics model did not accurately capture the DDRX behavior in Stage 1,it effectively simulated the DRX rate in Stage *** texture index was employed to assess the evolution of the texture isotropy during hot-torsion test,demonstrating significant improvement(>75%)in texture randomness before the commencement of Stage *** initial texture evolution is attributed to the rotation of parent grains and the substructure evolution,rather than to an increase in X_(DRX).

关键词： Al-7Mg alloys hot deformation hot torsion tests dynamic recrystazlliation microstructure texture

Ultrasonic Influence of Porosity Level on CFRP Composite Laminates Using Rayleigh Probe Waves

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Ultrasonic Influence of Porosity Level on CFRP Composite Lam...

A Review of Rechargeable Zinc-Air Batteries:Recent Progress and Future Perspectives

The Eighth International Conference on Fundamentals of Fracture（ICFF VIII）

作者： Je-Woong Park Do-Jung Kim kwang-hee im David K.Hsu Sun-Kyu Kim Kil-Sung Lee In-Young Yang Dept.of Naval Architecture and Ocean Eng. Chosun UniversityKwangju 501-759Korea Department of Automotive Eng. Woosuk UniversitySamrae-upWanju-kunChonbuk565-701Korea Center for Nondestructive Evaluation Iowa State UniversityAmesIowa 50011USA

It is found that a pitch-catch signal was more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composites(damages,fiber orientation,low level porosity,ply waviness,and cracks).The depth of the sampling volume where the pitch-catch signal came from was relatively shallow with the head-to-head miniature Rayleigh probes,but the depth can be increased by increasing the separation distance of the transmitting and

关键词： Ply-layup Orientation CFRP Peak-delay Measurement Method Contact Mode Porosity Level

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Nano-Micro Letters 2024年第7期16卷 358-401页

作者： Ghazanfar Nazir Adeela Rehman Jong-Hoon Lee Choong-hee Kim Jagadis Gautam kwang Heo Sajjad Hussain Muhammad Ikram Abeer AAlObaid Seul-Yi Lee Soo-Jin Park Department of Nanotechnology and Advanced Materials Engineering Hybrid Materials Research Center(HMC)Sejong UniversitySeoul 05006Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-RoSeodaemun-GuSeoul 03722Republic of Korea Department of Chemistry Inha UniversityIncheon 22212Republic of Korea Solar Cell Applications Research Lab Department of PhysicsGovernment College University LahoreLahore 54000 PunjabPakistan Department of Chemistry College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

Zinc-air batteries(ZABs)are gaining attention as an ideal option for various applications requiring high-capacity batteries,such as portable electronics,electric vehicles,and renewable energy *** offer advantages such as low environmental impact,enhanced safety compared to Li-ion batteries,and cost-effectiveness due to the abundance of ***,early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox *** advancements in restructuring the anode,utilizing alternative electrolytes,and developing bifunctional oxygen catalysts have significantly improved *** have achieved battery reversibility over thousands of cycles,introduced new electrolytes,and achieved energy efficiency records surpassing 70%.Despite these achievements,there are challenges related to lower power density,shorter lifespan,and air electrode corrosion leading to performance *** review paper discusses different battery configurations,and reaction mechanisms for electrically and mechanically rechargeable ZABs,and proposes remedies to enhance overall battery *** paper also explores recent advancements,applications,and the future prospects of electrically/mechanically rechargeable ZABs.

关键词： Zinc-air batteries Energy storage Affordability Reversibility

A dose-dependent bimodal switch by homologous Aux/IAA transcriptional repressors

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Molecular Plant 2024年第9期17卷 1407-1422页

作者： Hyung-Taeg Cho Minsu Lee hee-Seung Choi kwang-Ho Maeng Kyeonghoon Lee Ha-Yeon Lee Anindya Ganguly Hoonyoung Park Chang-Hoi Ho Department of Biological Sciences Seoul National UniversitySeoulKorea School of Earth and Environmental Sciences Seoul National UniversitySeoulKorea Department of Climate and Energy Systems Engineering Ewha Womans UniversitySeoulKorea

Combinatorial interactions between different regulators diversify and enrich the chance of transcriptional regulation in eukaryotic ***,a dose-dependent functional switch of homologous transcriptional repressors has rarely been ***,we show that SHY2,an auxin/indole-3-acetic acid(Aux/IAA)repressor,exhibits a dose-dependent bimodal role in auxin-sensitive root-hair growth and gene transcrip-tion in Arabidopsis,whereas other Aux/lAA homologs consistently repress the auxin *** co-repressor(TOPLESS[TPL])-binding affinity of a bimodal Aux/IAA was lower than that of a consistently re-pressing Aux/*** switch of a single amino acid residue in the TPL-binding motif between the bimodal form and the consistently repressing form switched their TPL-binding affinity and transcriptional and bio-logical roles in auxin *** on these data,we propose a model whereby competition between homologous repressors with different co-repressor-binding affinities could generate a bimodal output at thetranscriptional anddevelopmental levels.

关键词： auxin Aux/IAA dose-dependent regulation root hair transcription TOPLESS(TPL)