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Computers, Materials & Continua 2024年第5期79卷 3047-3065页

作者： chanho Park Takefumi Ogawa Graduate School of Engineering The University of TokyoTokyo113-0033Japan Information Technology Center The University of TokyoChiba277-0882Japan

Six degrees of freedom(6DoF)input interfaces are essential formanipulating virtual objects through translation or rotation in three-dimensional(3D)space.A traditional outside-in tracking controller requires the installation of expensive hardware in *** inside-out tracking controllers have been proposed,they often suffer from limitations such as interaction limited to the tracking range of the sensor(e.g.,a sensor on the head-mounted display(HMD))or the need for pose value modification to function as an input interface(e.g.,a sensor on the controller).This study investigates 6DoF pose estimation methods without restricting the tracking range,using a smartphone as a controller in augmented reality(AR)*** approach involves proposing methods for estimating the initial pose of the controller and correcting the pose using an inside-out tracking *** addition,seven pose estimation algorithms were presented as candidates depending on the tracking range of the device sensor,the tracking method(e.g.,marker recognition,visual-inertial odometry(VIO)),and whether modification of the initial pose is *** two experiments(discrete and continuous data),the performance of the algorithms was *** results demonstrate enhanced final pose accuracy achieved by correcting the initial ***,the importance of selecting the tracking algorithm based on the tracking range of the devices and the actual input value of the 3D interaction was emphasized.

关键词： Smartphone inside-out tracking 6DoF pose 3D interaction augmented reality

Phase stability and mechanical properties of wire+arc additively manufactured H13 tool steel at elevated temperatures

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Journal of Materials Science & Technology 2021年第8期67卷 80-94页

作者： A.N.M.Tanvir Md.R.U.A hsan Gijeong Seo Brian Bates chanho lee Peter K.Liaw Mark Noakese Andrzej Nycz Changwook Ji Duck Bong Kim Department of Mechanical Engineering Tennessee Technological UniversityCookevilleTN 38505USA Department of Manufacturing and Engineering Technology Tennessee Technological UniversityCookevilleTN 38505USA Center for Manufacturing Research Tennessee Technological UniversityCookevilleTN 38505USA Department of Materials Science and Engineering University of TennesseeKnoxvilleTN 37996USA Manufacturing Demonstration Facility Oak Ridge National LaboratoryOak RidgeTN 37830USA Advanced Forming Process R&D Group Korea Institute of Industrial TechnologyUlsan 44413Republic of Korea

Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near *** offers the benefits of inexpensive initial system setup and a high deposition rate for fabricating medium-and large-sized parts such as die-casting *** this study,AISI H13 tool steel,a popular die-casting tool metal,is manufactured by cold metal transfer(CMT)-based WAAM and is then comprehensively analyzed for its microstructural and mechanical ***-dependent phase combinations are observed,which could be explained by nonequilibrium thermal cycles that resulted from the layer-by-layer stacking mechanism used in *** addition,remelting and reheating of the layers reduces welding anomalies(e.g.,pores and voids).The metallurgical characteristics of the H13 strongly correlate with the mechanical *** combinations of phases at different locations of the additively manufactured part exhibit a periodic microhardness ***,Retained Austenite,Ferrite,and Carbide phases are found in combination at different locations of the part based on the part’s temperature distribution during additive ***,the tensile properties at elevated temperatures(23℃,300℃,and 600℃)are comparable to those from other WAAM and additive manufacturing(AM)*** X-ray diffraction results verify that the microstructural stability of the fabricated parts at high temperatures would allow them to be used in high temperatures.

关键词： Tool steel Martensitic steel Wire+arc additive manufacturing(WAAM) High temperature tensile test High temperature XRD

Fatigue behavior of high-entropy alloys： A review

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Science China(Technological Sciences) 2018年第2期61卷 168-178页

作者： CHEN PeiYong lee chanho WANG Shao-Yu SEIFI Mohsen LEWANDOWSKI John J DAHMEN Karin A JIA HaoLing XIE Xie CHEN BiLin YEH Jien-Wei TSAI Che-Wei YUAN Tao LIAW Peter K Department of Materials Science and Engineering The University of TennesseeKnoxville 37996，USA Department of Materials Science and Engineering Case Western UniversityCleveland 44106USA Department of Physics University of IllinoisUrbana 61801USA Department of Materials Science and Engineering 'National' Tsing Hua UniversityHsinchu 30013，Taiwan，China Department of Industry and System Engineering Ohio UniversityAthens 45701，USA

Fatigue failures cost approximately 4% of the United States' gross domestic product(GDP). The design of highly fatigue-resistant materials is always in demand. Different from conventional strategies of alloy design, high-entropy alloys(HEAs) are defined as materials with five or more principal elements, which could be solid solutions. This locally-disordered structure is expected to lead to unique fatigue-resistant properties. In this review, the studies of the fatigue behavior of HEAs during the last five years are summarized. The four-point-bending high-cycle fatigue coupled with statistical modelling, and the fatigue-crack-growth behavior of HEAs, are reviewed. The effects of sample defects and nanotwins-deformation mechanisms on four-point-bending high-cycle fatigue of HEAs are discussed in detail. The influence of stress ratio and temperature on fatigue-crack-growth characteristics of HEAs is also discussed. HEAs could exhibit comparable or greater fatigue properties, relative to conventional materials. Finally,the possible future work regarding the fatigue behavior of HEAs is suggested.

关键词： high-entropy alloys fatigue behaviour statistical modelling fatigue crack growth

Electrolyte accessibility of non-precious-metal catalysts with different spherical particle sizes under alkaline conditions for oxygen reduction reaction

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Journal of Energy Chemistry 2021年第1期30卷 326-331,I0011页

作者： Jiyeon lee Jong Gyeong Kim chanho Pak Graduate Program of Energy Technology School of Integrated TechnologyInstitute of Integrated TechnologyGwangju Institute of Science and TechnologyGwangju 61005Republic of Korea

Fuel cells are one of the most competitive alternative energy sources because their theoretical efficiency is~15%higher than that of internal combustion engines (ICEs) and they are considered cleaner and *** fuel cells are used to replace ICEs in cars and energy conversion systems,the system efficiency increases;furthermore,the process becomes more environmentally-friendly because fuel cells produce electricity by using only hydrogen and oxygen,obtained by purifying atmospheric air by filtering out dust and ***,their final product is only water,instead of pollutants like carboFuel cells are one of the most competitive alternative energy sources because their theoretical efficiency is~15%higher than that of internal combustion engines (ICEs) and they are considered cleaner and *** fuel cells are used to replace ICEs in cars and energy conversion systems,the system efficiency increases;furthermore,the process becomes more environmentally-friendly because fuel cells produce electricity by using only hydrogen and oxygen,obtained by purifying atmospheric air by filtering out dust and ***,their final product is only water,instead of pollutants like carbon dioxide.n dioxide.

关键词： Non-precious-metal catalyst Oxygen reduction reaction Size effect Electrolyte accessibility Alkaline fuel cell

Multifunctional Ir–Ru alloy catalysts for reversal-tolerant anodes of polymer electrolyte membrane fuel cells

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Journal of Materials Science & Technology 2021年第1期60卷 105-112页

作者： Seung Woo lee Bongho lee Chaekyung Baik Tae-Yang Kim chanho Pak Graduate Program of Energy Technology School of Integrated TechnologyInstitute of Integrated TechnologyGwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Research Institute for Solar and Sustainable Energies Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea

To address the problem of fuel starvation in fuel-cell electric vehicles,which causes cell voltage reversal and results in cell failure when repeated continuously,we developed a reversal-tolerant anode(RTA) to promote water oxidation in preference to carbon *** carbon-supported Ir-Ru alloys with different compositions are employed as RTA catalysts in an acidic polyol solution and are shown to exhibit composition-dependent average crystallite sizes of <5.33 *** adopted approach allows the generation of relatively well-dispersed Ir-Ru alloy nanoparticles on the carbon support without severe *** activity of IrRu_(2)/C for the hydrogen oxidation reaction is 1.10 times that of the stateof-the-art Pt/C *** reversal testing by simulation of fuel starvation reveals that the durability of IrRu_(2)/C(~7 h) significantly exceeds that of the conventional Pt/C catalyst(~10 min) and is the highest value reported so ***,the developed Ir-Ru alloy catalyst can be used to fabricate practical RTAs and replace Pt catalysts in the anodes of polymer electrolyte membrane fuel cells.

关键词： Polymer electrolyte membrane fuel cell Polyol process Reversal-tolerant anode Oxygen evolution reaction Hydrogen oxidation reaction

Strategy for Creating AR Applications in Static and Dynamic Environments Using SLAM-and Marker Detector-Based Tracking

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Computer Modeling in Engineering & Sciences 2022年第4期131卷 529-549页

作者： chanho Park Hyunwoo Cho Sangheon Park Sung-Uk Jung Suwon lee Electronics and Telecommunications Research Institute Daejeon34129Korea Graduate School of Engineering The University of TokyoTokyo113-0033Japan School of Computer Science and The Research Institute of Natural Science Gyeongsang National UniversityJinju-si52828Korea

Recently,simultaneous localization and mapping(SLAM)has received considerable attention in augmented reality(AR)libraries and *** the assumption of scene rigidity is common in most visual SLAMs,this assumption limits the possibilities of AR applications in various real-world *** this paper,we propose a new tracking system that integrates SLAMwith amarker detection module for real-time AR applications in static and dynamic *** the proposed system assumes that the marker is movable,SLAM performs tracking andmappingof the static scene except for themarker,andthemarker detector estimates the 3-dimensional pose of the marker attached to the dynamic *** can place SLAM maps,cameras,and dynamic objects(markers)on the same coordinate system,and we can also accurately augment AR resources in real-time on both the static scene and dynamic objects ***,having a static map of the scene in advance has the advantage of being able to performtracking of static and dynamic environments with mapping *** this paper,we evaluate whether the proposed tracking systemis suitable for AR applications and describe a strategy for creating AR applications in static and dynamic environments with a demonstration.

关键词： Augmented reality SLAM marker tracking coordinate system

New strategy for reversal tolerant anode for automotive polymer electrolyte fuel cell

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Chinese Chemical Letters 2019年第6期30卷 1186-1189页

作者： chanho Pak Seung Woo lee Chaekyung Baik Bong Ho lee Dae Jong You Eunyoung You Graduate Program of Energy Technology School of Integrated Technology Institute of Integrated Technology Gwangju Institute of Science and Technology Gwangju 61005 Republic of Korea Fuel Cell Engineering Core Technology Team Division of Electric Powertrain Hyundai Mobis Co. Ltd. Yongin Gyeonggi-do 16891 Republic of Korea

Since the commercialization of the fuel cell electric vehicles (FCEVs), the polymer electrolyte membrane fuel cell system has been actively improved as a powertrain for ultimate environment-friendly vehicle. During the FCEV operation, various transient conditions such as start-up/shut-down and fuel starvation occur irregularly, which deteriorates the durability of the membrane electrode assembly. In particular, when fuel starvation occurs, the carbon support in the anode is oxidized within few minutes, thus the mitigation of this phenomenon is essential for securing the durability. This short review introduces the concept of reversal tolerant anode (RTA), which is a mitigation method using an oxygen evolution catalyst and reviews some previous reports. In addition, new approach for RTA suggested by authors recently, which is the replacement of Pt anode catalyst by multifunctional IrRu alloy catalyst that simultaneously exhibits the activities for the hydrogen oxidation reaction and the oxygen evolution reaction is introduced.

关键词： Multifunctional IrRu alloy catalyst Reversal tolerant anode Hydrogen oxidation reaction catalyst Oxygen evolution reaction catalyst Cell reversal durability Polymer electrolyte membrane fuel cell

Zwitterion-assisted transition metal dichalcogenide nanosheets for scalable and biocompatible inkjet printing

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Nano Research 2020年第10期13卷 2726-2734页

作者： Hyeokjung lee Min Koo chanho Park Madhumita Patel Hyowon Han Tae Hyun Park Pawan Kumar Won-Gun Koh Cheolmin Park Department of Materials Science and Engineering Yonsei University Seoul 03722Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei UniversitySeoul 03722Republic of Korea

Inkjet printing of two-dimensional(2D)transition metal dichalcogenide(TMD)nanosheets fabricated by liquid-phase exfoliation(LPE)allows simple,mass-producible,and low-cost photo-electronic *** LPE processes involve toxic and environmentally hazardous solvents;however,dispersants have restricted the extent of applications of 2D-TMD ***,various 2D-TMD nanosheets,including MoS2,MoSe2,WS2,and WSe2,in addition to few-layered graphene,are inkjet-printed using a LPE process based on zwitterionic dispersants in *** with cationic and anionic species are water-soluble,while alkyl chain moieties associated with two ionic species adhere universally on the surface of TMD nanosheets,resulting in high throughput liquid exfoliation of the *** zwitterion-assisted TMD nanosheets in water are successtully employed as an ink without the need for additives to adjust the viscosity and surface tension of the ink for use in an office inkjet printer;this gives rise to A4 scale,large-area inkjet-printed images on diverse substrates,such as metals,oxides,and polymer substrates patchable onto human *** with conductive graphene nanosheet inks allowed the development of mechanically flexible,biocompatible-printed arrays of photodetectors with pixelated MoSe2 channels on a paper exhibiting a photocurrent ON/OFF ratio of approximately 1038 and photocurrent switching of 500 ms.

关键词： transition metal dichalcogenide nanosheets zwitterions zwitterion-assisted liquid-phase exfoliation scalable inkjet printing biocompatible

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)

Progress of Materials and Devices for Neuromorphic Vision Sensors

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Nano-Micro Letters 2022年第12期14卷 239-271页

作者： Sung Woon Cho chanho Jo Yong-Hoon Kim Sung Kyu Park Department of Electrical and Electronics Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Advanced Components and Materials Engineering Sunchon National UniversitySunchŏnJeonnam 57922Republic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea SKKU Advanced Institute of Nanotechnology(SAINT) Sungkyunkwan UniversitySuwon 16419Republic of Korea

The latest developments in bio-inspired neuromorphic vision sensors can be summarized in 3 keywords:smaller,faster,and smarter.(1)Smaller:Devices are becoming more compact by integrating previously separated components such as sensors,memory,and processing *** a prime example,the transition from traditional sensory vision computing to in-sensor vision computing has shown clear benefits,such as simpler circuitry,lower power consumption,and less data redundancy.(2)Swifter:Owing to the nature of physics,smaller and more integrated devices can detect,process,and react to input more *** addition,the methods for sensing and processing optical information using various materials(such as oxide semiconductors)are evolving.(3)Smarter:Owing to these two main research directions,we can expect advanced applications such as adaptive vision sensors,collision sensors,and nociceptive *** review mainly focuses on the recent progress,working mechanisms,image pre-processing techniques,and advanced features of two types of neuromorphic vision sensors based on near-sensor and in-sensor vision computing methodologies.

关键词： In-sensor computing Near-sensor computing Neuromorphic vision sensor Optoelectronic synaptic circuit Optoelectronic synapse