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Effect of Sb Addition on Microstructure and Mechanical Properties of Al-18B-4O-33/AS-52 Magnesium Matrix Composites

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Journal of Materials Science & Technology 2008年第1期24卷 99-101页

作者： Wookjin Lee Ikmin park x yongho park School of Materials Science and Engineering Pusan National University San 30 Jangjeon-dong Geumjeong-gu Busan 609-735 Korea

The effect of antimony addition on the microstructure of Mg-Al-Si magnesium matrix composite was investi- *** addition of Sb can modify the morphology of Mg-2Si particles which have Chinese script shape to fine polygonal *** matrix composite with Alborex whisker was successfully fabricated by using a squeeze infiltration *** strength and elongation were increased in the Sb modified alloy and the composite at both room and high temperatures.

关键词： Magnesium Metal matrix composites (MMC) Composite

Exploration of cobalt selenite-carbon composite porous nanofibers as anode for sodium-ion batteries and unveiling their conversion reaction mechanism

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Journal of Materials Science & Technology 2021年第30期89卷 24-35页

作者： Jin-Sung park Gi Dae park yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul136-713Republic of Korea

Efforts have been made to develop a promising anode material with a novel composition for sodiumion batteries(SIBs).In this study,the sodium-ion storage mechanism of transition metal selenite that comprises transition metal cation coupled with two anions is *** cobalt selenite(CoSeO_(3))-carbon composite nanofibers containing numerous pores are synthesized via electrospinning *** heat treatment of the electrospun nanofibers containing selenium,CoSe_(2)nanoclusters are *** the subsequent oxidation,CoSe_(2)transformed into amorphous CoSeO_(3)and some part of carbon was oxidized into CO_(2),leaving the pores inside the *** unveil the electrochemical reaction mechanism,analytical methods including cyclic voltammetry,ex-situ X-ray photoelectron spectroscopy,ex-situ transmission electron microscopy,and in-situ electrochemical impedance spectroscopy techniques were *** on the analyses,the following conversion reaction from the second cycle onward is suggested:CoO+xSeO_(2)+(1-x)Se+4(x+1)Na^(+)+4(x+1)e~-?Co+(2x+1)Na_(2)O+Na_(2)***,the electrochemical properties of porous CoSeO_(3)-carbon composite nanofibers are analyzed in *** anode material exhibited stable cycle stability up to 200 cycles at 0.5 A g^(-1)and high rate performance up to 5 A g^(-1).

关键词： Anode materials Sodium-ion batteries Conversion reaction Metal selenite Electrospinning

Density functional theory study on the role of ternary alloying elements in TiFe-based hydrogen storage alloys

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Journal of Materials Science & Technology 2021年第33期92卷 148-158页

作者： Won-Seok Ko Ki Beom park hyung-Ki park School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea Functional Materials and Components R&D Group Korea Institute of Industrial TechnologyGangneung 25440Republic of Korea

The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory *** a basic step for examinations,the site preference of each alloying element in the stoichiometric and nonstoichiometric B2TiFe compounds was clarified considering possible antisite *** on the revealed site preference,the effect of various possible ternary elements on the hydrogen storage was examined by focusing on the formation enthalpies of TiFeh and TiFeh_(2) hydrides,which were closely related to the change in the location of plateaus in the pressure-composition-temperature *** physical properties such as the volume expansion due to hydride formation were also examined to provide additional criteria for selecting optimum alloying conditions in future alloying design *** alloying elements that maximize the grain boundary embrittlement due to the solute segregation were proposed for the enhanced initial activation of TiFe-based hydrogen storage alloys.

关键词： hydrogen storage alloy Titanium-iron Density functional theory calculation Metallic hydride

Strong interlayer coupling and stable topological flat bands in twisted bilayer photonic Moiré superlattices

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Light(Science & Applications) 2022年第10期11卷 2523-2529页

作者： Chang-hwan yi hee Chul park Moon Jip park Center for Theoretical Physics of Complex Systems Institute for Basic Science(IBS)Daejeon 34126Republic of Korea

The moiré superlattice of misaligned atomic bilayers paves the way for designing a new class of materials with wide *** this work,we propose a photonic analog of the moiré superlattice based on dielectric resonator *** sharp contrast to van der Waals materials with weak interlayer coupling,we realize the strong coupling regime in a moiré superlattice,characterized by cascades of robust flat bands at large ***,we find that these flat bands are characterized by a non-trivial band topology,the origin of which is the moiré pattern of the resonator *** physical manifestation of the flat band topology is a robust one-dimensional conducting channel on edge,protected by the reflection symmetry of the moiré *** explicitly breaking the underlying reflection symmetry on the boundary terminations,we show that the first-order topological edge modes naturally deform into higher-order topological corner *** work pioneers the physics of topological phases in the designable platform of photonic moiré superlattices beyond the weakly coupled regime.

关键词： topological bands coupling

Efficient thermal management and all-season energy harvesting using adaptive radiative cooling and a thermoelectric power generator

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Journal of Energy Chemistry 2023年第9期84卷 496-501页

作者： Chanil park Woohwa Lee Choyeon park Sungmin park Jaeho Lee yong Seok Kim youngjae yoo Advanced Materials Division Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea Department of Mechanical and Aerospace Engineering University of CaliforniaIrvineCA 92617United States Department of Advanced Materials Engineering Chung-Ang UniversityAnseong 17546Republic of Korea

Passive daytime radiative cooling(PDRC) is useful for thermal management because it allows an object to emit terrestrial heat into space without the use of additional *** produce sub-ambient temperatures under direct sunlight,PDRC materials are designed to reduce their absorption of solar energy and to enhance their long-wavelength infrared(LWIR) *** recent years,many photonic structures and polymer composites have been studied to improve the cooling system of ***,in cold weather(i.e. during winter in cold climates),buildings need to be kept warm rather than cooled due to heat *** overcome this limitation,temperature-responsive radiative cooling is a promising *** the present study,adaptive radiative cooling(ARC) film fabricated from a polydimethylsiloxane/hollow SiO_(2) microsphere/thermochromic pigment composite was *** found that the ARC film absorbed solar radiation under cold conditions while exhibiting radiative cooling at ambient temperatures above 40℃.Thus,in outdoor experiments,the ARC film achieved sub-ambient temperatures and had a theoretical cooling power of 63.2 W/m~2 in hot *** also demonstrated that radiative cooling with an energy harvesting system could be used to improve the energy management of buildings,with the thermoelectric module continuously generating output power using the ARC ***,we believe that our proposed ARC film can be employed for efficient thermal management of buildings and all-season energy harvesting in the near future.

关键词： Thermal management Daytime radiative cooling Temperature-adaptive film Thermoelectric device Energy harvesting

Stress analysis model of strip winding system with a sleeve for a coil of thin stainless steel

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Journal of Iron and Steel Research International 2017年第1期24卷 1-7页

作者： yong-hui park Kyutae park Sung-yeun Won Wan-kee hong hyun-chul park Graduate School of Engineering Masterships Pohang University of Science and Technology(POSTECH)Kyungbuk 790 784PohangRepublic of Korea Mechanical Engineering Pohang University of Science and Technology(POSTECH)Kyungbuk 790-784PohangRepublic of Korea Mechanical Facility Research Group Engineering Solution CenterPOSCOKyungbuk 790-360PohangRepublic of Korea

In a strip winding process,the sleeve is a hollow cylinder that is mounted between a strip coil and a mandrel to maintain uniform coil shape when the strip coil is very thin,but its deformation behavior has not been investigated ***,a finite element（FE）model was presented to calculate the stress distribution in a sleeve and strip coil when 1-3mm-thick stainless steel was wound around the *** FE model was developed by extending aprevious model by adding a sleeve between the mandrel and strip,and by modifying the boundary and interaction *** strip winding process was divided into an initial process and a steady-state *** the initial process,the minimum and maximum pressure required on the belt wrapper to maintain coil shape by self-friction of the strip was calculated by the FE model when the belt wrapper is ejected at the end of the initial *** the initial process,an analytical model of the steady-state process was established to calculate the stress distribution and was compared with the FE model to validate *** suggested analytical model took 11 sto give the same stress distribution that the FE model took 30 dto produce.

关键词： Strip winding system Belt wrapper Grooved joint Radial stress hoop stress Von-Mises stress Interference fit

System lifecycle processes for cyber security in a research reactor facility

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Science China(Information Sciences) 2014年第7期57卷 247-258页

作者： park JaeKwan park Jeyun KIM youngKi Korea Atomic Energy Research Institute Daedeok-daero 989-111Dukjin-dongYuseong-guDaejeonKorea

The digitalization of nuclear facilities has brought many benefits,including high performance and convenient maintainability,in terms of facility ***,cyber accidents accompanied by the use of digital technologies have increased,and cyber security has been one of the most important issues in the nuclear industry *** guidelines have been published for nuclear power plants,but it is difficult to apply all requirements within the guidelines to research reactor facilities because the characteristics in terms of facility scale,purpose,and system design,are different from those of power *** address this emerging topic,this paper introduces system lifecycle processes for cyber security in a research reactor *** addresses the integration of activities for securing systems and guarding a facility safely using the practices at a research reactor facility.

关键词： software project management computer-based safety systems cyber security security program

Development of a cloud condensation nuclei(CCN)counter using a laser and charge-coupled device(CCD)camera

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Frontiers of Environmental Science & Engineering 2011年第3期5卷 313-319页

作者： Mikyung park Jinkwan Oh Kihong park School of Environmental Science and Engineering Gwangju Institute of Science and TechnologyGwangju 500-712The Republic of Korea

A continuous flow streamwise thermal gradientcloud condensation nuclei(CCN)counter with anaerosol focusing and a laser-charge-coupled device(CCD)camera detector system was developed *** countingperformance of the laser-CCD camera detector system wasevaluated by comparing its measured number concentrationswith those measured with a condensation particlecounter(CPC)using polystyrene latex(PSL)and NaClparticles of varying *** CCD camera parameters(***,gain,gamma,and exposure time)wereoptimized to detect moving particles in the sensing volumeand to provide the best image to count *** CCNcounter worked well in the particle number concentrationrange of 0.6-8000#·cm^(-3)and the minimum detectablesize was found to be 0.5μ*** supersaturation in theCCN counter with varying temperature difference wasdetermined by using size-selected sodium chloride particlesbased on Köhler *** developed CCNcounter was applied to investigate CCN activity ofatmospheric ultrafine particles at 0.5%*** showed that CCN activity increased with increasingparticle size and that the higher CCN activation forultrafine particles occurred in the afternoon,suggesting thesignificant existence of hygroscopic or soluble species inphotochemically-produced ultrafine particles.

关键词： aerosol cloud condensation nuclei(CCN)counter ultrafine particle

GENERAL DECAy FOR A QUASILINEAR SySTEM OF VISCOELASTIC EQUATIONS WITh NONLINEAR DAMPING

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Acta Mathematica Scientia 2012年第4期32卷 1321-1332页

作者： Jong yeoul park Sun hye park Department of Mathematics Pusan National UniversityBusan 609-735 South Korea

In this paper, we consider a system of coupled quasilinear viscoelastic equa- tions with nonlinear damping. We use the perturbed energy method to show the general decay rate estimates of energy of solutions, which extends some existing results concerning a general decay for a single equation to the case of system, and a nonlinear system of viscoelastic wave equations to a quasilinear system.

关键词： general decay coupled quasilinear equations viscoelastic equations perturbed energy method