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Influences of the Welding Heat Input and the Repeated Repair Welding on Ti–3Al–2.5V Titanium Alloy

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 684-691页

作者： Hui-Jun Yi Yong-Jun lee kwang-O lee School of Mechanical Engineering Pusan National University

The primary purpose of this study was to determine the effects of gas tungsten arc welding heat input on the high-temperature tensile properties, toughness, and microstructural features of titanium alloy Ti-3A1-2.5V. The secondary objective was to examine the effect of the repeated repair welding on the properties of the alloy. It was also found that the mechanical properties progressively decreased with increasing the repair welding cycles, especially in the case of the weldment after the first welding repair. It was observed that the sizes of the acicular and prior β grain boundaries as well as the volume fraction of the acicular phases increased with increasing the welding heat input. In addition, the amount and size of the acicular a1 phases were found to increase with increasing the repair welding cycles.

关键词： Ti-3AI-2.5V Repair welding Heat input Tensile properties Microstructure

Etching characteristics of thin SiON films using a liquefied perfluorocarbon precursor of C_6F_(12)O with a low global warming potential

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Plasma Science and Technology 2020年第10期22卷 135-144页

作者： Junmyung lee Yunho NAM Jongchan lee Hyun Woo lee kwang-Ho KWON Department of Control and Instrumentation Engineering Korea UniversitySejong 30019Republic of Korea Department of Aeronautic Computer Engineering Hanseo UniversitySeosan 31962Republic of Korea

Perfluorocarbon gas is widely used in the semiconductor ***,perfluorocarbon has a negative effect on the global environment owing to its high global warming potential(GWP) *** alternative solution is ***,we evaluated the possibility of replacing conventional perfluorocarbon etching gases such as CHF_3 with C_6F_(12)O,which has a low GWP and is in a liquid state at room *** this study,silicon oxynitride(SiON) films were plasma-etched using inductively coupled CF4+C_6F_(12)O+O_2 mixed ***,the etching characteristics of the film,such as etching rate,etching profile,selectivity over Si,and photoresist,were investigated.A double Langmuir probe was used and optical emission spectroscopy was performed for plasma *** addition,a contact angle goniometer and x-ray photoelectron spectroscope were used to confirm the change in the surface properties of the etched SiON film ***,the etching characteristics of the C_6F_(12)O mixed plasma exhibited a lower etching rate,higher SiON/Si selectivity,lower plasma damage,and more vertical etched profiles than the conventional CHF_3 mixed *** addition,the C_6F_(12)O gas can be recovered in the liquid state,thereby decreasing global *** results confirmed that the C_6F_(12)O precursor can sufficiently replace the conventional etching gas.

关键词： global warming potential perfluorocarbon silicon oxynitride etching characteristics liquid-state perfluorocarbon

Friction and wear of textured surfaces produced by 3D printing

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Science China(Technological Sciences) 2017年第9期60卷 1400-1406页

作者： HONG Yi ZHANG Peng lee kwang-Hee lee Chul-Hee Department of Mechanical Engineering Inha University Incheon 402-751 Korea

Surface texture patterns have great potential for improving tribological performance in terms of reducing friction and wear. The most common methods for surface texatring are laser and injection molding. The 3D printing method is also used to build parts, patterns, and molds that feature fine details for a wide range of applications because texture manufacturing by 3D printing is faster, more flexible, and less expensive than traditional techniques. To date, there has been no research on textured surfaces produced by 3D printing. Therefore, a new fabrication method using 3D printing to improve friction and wear properties is a topic worth exploring. In this study, a reciprocating friction tester was used to evaluate the friction and wear properties of different surface textures produced by 3D printing. The surface of specimens was examined by electron microscope and scanning electron microscope before and after the test. The results show that surface texturing can be applied to 3D printed parts to improve their friction and wear performance.

关键词： three-dimensional (3D) printing texture friction wear

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

High-efficiency design of a mixed-flow pump

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Science China(Technological Sciences) 2010年第1期53卷 24-27页

作者： KIM jin-Hyuk AHN Hyung-jin KIM kwang-Yong Department of Mechanical Engineering Inha University253Yonghyun-DongIncheon402-751Republic of Korea Industrial Machinery Division Iljin Electric Co.Ltd5-5Hwasu-DongIncheon401-020Republic of Korea

High-efficiency design of a mixed-flow pump has been carried out based on numerical analysis of a three-dimensional viscous *** analysis,the Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized by finite-volume *** grid system was constructed in the computational domain,which has O-type grids near the blade surfaces and H/J-type grids in other *** numerical results were validated with experimental data for the heads and hydraulic efficiencies at different flow *** hydraulic efficiency at the design flow coefficient was evaluated with variation of the geometric variables,i.e.,the area of the discharge and length of the vane in the *** result has shown that the hydraulic efficiency of a mixed-flow pump at the design condition is improved by the modification of the geometry.

关键词： mixed-flow pump numerical analysis impeller vane diffuser head hydraulic efficiency

Broadcast-Based Spatial Queries

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Journal of Computer Science & Technology 2005年第6期20卷 811-821页

作者： kwang-jin Park Moon-Bae Song Chong-Sun Hwang Department of Computer Science and Engineering Korea University 5-1 Anam-Dong Seongbuk-Ku Seoul 136-701 Korea

Indexing techniques have been developed for wireless data broadcast environments, in order to conserve the scarce power resources of the mobile clients. However, the use of interleaved index segments in a broadcast cycle increases the average access latency for the clients. In this paper, the broadcast-based spatial query processing methods （BBS） are presented for the location-based services. In the BBS, broadcasted data objects are sorted sequentially based on their locations, and the server broadcasts the location dependent data along with an index segment. Then, a sequential prefetehing and caching scheme is designed to reduce the query response time. The performance of this scheme is investigated in relation to various environmental variables, such as the distributions of the data objects, the average speed of the clients and the size of the service area.

关键词： broadcasting location-aware caching prefetching mobile computing

LiTFSI salt concentration effect to digest lithium polysulﬁdes for high-loading sulfur electrodes

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Journal of Energy Chemistry 2023年第3期78卷 574-581,I0015页

作者： jin-kwang Song Moonsoo Kim Seongbae Park Young-Jun Kim SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Nano Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea

Sulfur utilization improvement and control of dissolved lithium polysulﬁde(LiPS;Li_(2)S x,2 详细信息

Sulfur utilization improvement and control of dissolved lithium polysulﬁde(LiPS;Li_(2)S x,2

关键词： Lithium-sulfur battery Electrolyte concentration Li2S deposition High-loading sulfur electrode

Order Relation for Type-2 Fuzzy Values

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Tsinghua Science and Technology 2003年第1期8卷 30-36页

作者： Seungsoo lee kwang H. lee Doheon lee Department of Electrical Engineering and Computer Science KAIST Department of Electrical Engineering and Computer Science KAISTDepartment of BioSystems KAIST 373-1 Guseong-dong Yuseong-gu Daejeon 305-701 Republic of Korea373-1 Guseong-dong Yuseong-gu Daejeon 305-701 Republic of KoreaDepartment of BioSystems KAIST 373-1 Guseong-dong Yuseong-gu Daejeon 305-701 Republic of Korea373-1 Guseong-dong Yuseong-gu Daejeon 305-701 Republic of Korea

In this paper an order relation and a ranking method for type-2 fuzzy values are proposed. In order to compare type-2 fuzzy sets, the concepts of satisfaction function for continuous fuzzy values, h-level type-2 fuzzy values and strong order relation are introduced. The proposed method is an approach based on the possibility theory, and it generates a ranking sequence with the greatest possibility. Some properties of the proposed method are also analyzed.

关键词： type-2 fuzzy set fuzzy comparison fuzzy ranking fuzzy order relation

Annotated survey and perspectives on rail transport energy system RAMS evaluation technology

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Green Energy and Intelligent Transportation 2024年第3期3卷 75-90页

作者： Ruifeng Shi Lingzhi Zhang Feng Lin jin Ning Limin Jia kwang Y.lee School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China China Institute of Energy and Transportation Integrated Development Beijing 102206China State Key Lab of Rail Traffic Control&Safety Beijing Jiaotong UniversityBeijing 100044China Department of Electrical and Computer Engineering Baylor UniversityWacoTX 76798USA

The rail transit system plays a crucial role in modern *** the increasing demand for clean and green energy in the transport sector,its energy system is expected to achieve low-carbon and highly efficient energy utilization in rail ***,the gradual development of the rail transport energy system has led to an increase in its complexity,and the rising difficulty of system assessment has faced the limitations of traditional assessment ***,it is essential to develop effective assessment *** paper begins by providing a systematic review of the development status of Reliability,Availability,Maintainability and Safety(RAMS)assessment and analyzing the shortcomings of traditional RAMS assessment technology in the context of rail transit energy ***,based on the four fundamental properties of RAMS,it summarizes the current state of key assessment technologies in the field of rail ***,the paper delves into the challenges and potential solutions concerning the implementation of RAMS assessment technology for rail transit energy ***,the paper offers an outlook on the future development of RAMS assessment for rail transport energy *** comprehensively analyzing these aspects,the paper aims to contribute valuable insights into optimizing the rail transit energy system,promoting its sustainable and efficient operation in the context of clean and green energy utilization.

关键词： Integration of energy and transportation RAMS evaluation Rail transit energy system