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Journal of Materials Science & Technology 2020年第14期47卷 15-24页

作者： Wonjoo Lee Yuhyeong jeong Jae-Wook Lee Howon Lee Seong-hoon Kang Young-Min Kim Jonghun Yoon Department of Mechanical Design Engineering Hanyang University222Wangsimni-roSeongdong-guSeoul 04763Republic of Korea Materials Deformation Department Korea Institute of Materials Science797 ChangwondaeroSeongsan-guChangwon-siGyeongnam-do 51508Republic of Korea Department of Mechanical Engineering Hanyang University55 Hanyangdaehak-roSangnok-guAnsan-siGyeonggi-do 15588Republic of Korea

To predict the dendrite morphology and microstructure evolution in the solidification of molten metal,numerically,lattice Boltzmann method(LBM)-cellular automata(CA)model has been developed by integrating the LBM to solve the mass transport by diffusion and convection during solidification and the CA to determine the phase transformation with respect to the solid fraction based on the local equilibrium *** is successfully validated with analytic solutions such as Lipton-Glicksman-Kurz(LGK)model in static melt,and Oseen-Ivantsov solution under the fluid flow conditions in terms of tip radius and velocity of the dendrite *** proposed LBM-CA model does not only describe different types of dendrite formations with respect to various solidification conditions such as temperature gradient and growth rate,but also predict the primary dendrite arm spacing(PDAS)and the secondary dendrite arm spacing(SDAS),quantitatively,in directional solidification(DS)experiment with Ni-based superalloy.

关键词： Cellular automata(CA) Lattice Boltzmann method(LBM) Dendritic growth Directional solidification

Effect of Palladium Nanoparticles on Photocatalytic Characteristics of N doped Titania Catalyst

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Journal of Materials Science & Technology 2015年第6期31卷 664-669页

作者： Jong-Ho Lee jeong-Il Youn Young-Jig Kim han-Jun Oh Department of Chemistry Hanseo University School of Advanced Materials Engineering Sungkyunkwan University Department of Materials Science Hanseo University

To improve the photocatalytic efficiency of TiO2nanotubular catalyst,N doped and Pd decorated titania nanotubes was successfully synthesized via anodizing,hydrazine hydrate treatment and photoreduction of Pd *** small Pd nanoparticles were precipitated on TiO2nanotubes through photoreduction of Pd ions,and its distribution is relatively *** X-ray photoelectron spectrometry（XPS） result,the N 1s spectrum represents two peaks with binding energy at 399.7 and 400.7 eV,which suggests that the nitrogen elements doped by hydrazine hydrate treatment are located in interstitial sites of the TiO2crystalline *** N doped TiO2nanotubes with Pd particles,a high photocurrent was detected due to increase of interface charge carrier separation ***,N doped and Pd decorated TiO2nanotubes exhibited much higher dye destruction efficiency and rate constant due to the synergistic effect of the N dopant and the Pd deposition on TiO2nanotubes.

关键词： Pd nanoparticle Titania nanotube Anodizing Dye dec

Selective laser melting of Fe-Ni-Cr layer on AISI H13 tool steel

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中国有色金属学会会刊：英文版 2009年第4期19卷 921-924页

作者： Byeong-Don JOO jeong-Hwan JANG Jae-Ho LEE Young-Myung SON Young-hoon MOON School of Mechanical Engineering Pusan National University

An attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel was performed with selective laser ***-Ni-Cr coating was produced by experimental facilities consisting of a 200 W fiber laser which can be focused to 80 μm and atmospheric chamber which can control atmospheric pressure with N2 or *** layer was fabricated with various process parameters such as laser power,scan rate and fill *** quality and coating thickness were measured and *** different surface patterns,such as typeⅠ,typeⅡand type Ⅲ,are shown with various test conditions and smooth regular pattern is obtained under the conditions as 10 μm of fill spacing,50-350 mm/s of scan rate and 40 μm of fill spacing,10-150 mm/s of scan *** maximum coating thickness is increased with power elevation or scan rate drop,and average thickness of 10 μm fill spacing is lower than that of 40 μm fill spacing.

关键词：镍铬涂层工具钢激光熔融社会扫描速度铁涂层厚度光纤激光器

Accelerated identification of equilibrium structures of multicomponent inorganic crystals using machine learning potentials

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npj Computational Materials 2022年第1期8卷 1027-1036页

作者： Sungwoo Kang Wonseok jeong Changho Hong Seungwoo Hwang Youngchae Yoon Seungwu han Department of Materials Science and Engineering Seoul National UniversitySeoul08826Korea

The discovery of multicomponent inorganic compounds can provide direct solutions to scientific and engineering challenges,yet the vast uncharted material space dwarfs synthesis *** the crystal structure prediction(CSP)may mitigate this frustration,the exponential complexity of CSP and expensive density functional theory(DFT)calculations prohibit material exploration at ***,we introduce SPINNER,a structure-prediction framework based on random and evolutionary *** speed and accuracy of neural network potentials(NNPs),the program navigates configurational spaces 10^(2)–10^(3) times faster than DFT-based ***,SPINNER incorporates algorithms tuned for NNPs,achieving performances exceeding conventional *** blind tests on 60 ternary compositions,SPINNER identifies experimental(or theoretically more stable)phases for~80%of *** benchmarked against data-mining or DFT-based evolutionary predictions,SPINNER identifies more stable phases in many *** developing a reliable and fast structure-prediction framework,this work paves the way to large-scale,open exploration of undiscovered inorganic crystals.

关键词： materials inorganic equilibrium

Effect of Al coating conditions on laser weldability of Al coated steel sheet

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中国有色金属学会会刊：英文版 2009年第4期19卷 946-951页

作者： Jung-han LEE Jong-Do KIM Jin-Seok OH Seo-jeong PARK Graduate School Korea Marine University Division of Marine Engineering System Korea Marine University Welding Research Center

Al coated steel sheets with excellent heat resistance,thermal reflection,and corrosion resistance are widely used in various *** laser weldability of the Al coated steel sheet for full penetration welding was *** phenomenon caused by intermixed aluminum and behavior of aluminum in the weld were *** coated steel sheets that have various thickness and coating mass were prepared for laser *** effects of parameters such as welding conditions and Al coating conditions were *** content mixed in the weld after laser welding was evaluated,and then a correlation between the mixed Al and mechanical properties was *** results show that the Al-rich zones which have Fe-Al intermetallic compounds are found in the *** intermetallic compounds cause the decreased strength of the weld.

关键词：铝合金焊接钢板焊接激光焊接 Al涂层金属间化合物涂层钢板涂层质量焊接条件

Effect of Laser Parameters on Sintered Powder Morphology

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Journal of Materials Science & Technology 2010年第4期26卷 375-378页

作者： Byeong-Don Joo jeong-Hwan Jang Jae-Ho Lee Young-Myung Son Young-hoon Moon Engineering Research Center for Net Shape and Die Manufacturing School of Mechanical EngineeringPusan National University

Selective laser sintering is a kind of rapid prototyping process whereby a three-dimensional part is built layerwise by laser scanning a powder. This process is highly inffuenced by powder and laser parameters such as laser power, scan rate, spot size and layer thickness. Therefore a study on fabricating a line with Fe-Ni-Cr powder on AISI H13 tool steel has been performed by selective laser sintering. In this study, fabrication was performed by experimental facilities consisting of a 200W fiber laser which can be focused to 0.08 mm and atmospheric chamber which can control atmospheric pressure with argon. The line was fabricated with various laser power, scan rate and layer thickness. Line width and surface quality were investigated. With power increase or layer thickness decrease, line width was decreased and line surface quality was improved with scan rate optimization.

关键词： Selective laser sintering Direct fabrication Fiber laser

Application of direct laser metal tooling for AISI H13 tool stee

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中国有色金属学会会刊：英文版 2009年第B09期19卷 284-287页

作者： Jae-Ho LEE jeong-Hwan JANG Byeong-Don JOO Hong-Sup YIM Young-hoon MOON School of Mechanical Engineering Pusan National University

In the die industry, it is commonly agreed that residual tool life can be successfully extended by timely repair of damaged surfaces. Traditionally, the main repair process is tungsten inert gas (TIG) welding, but a new process called direct laser metal tooling (DLMT) emerges. DLMT is a manual process, of which results depend on the materials of the powders and tools, the laser process and parameters. This technology is a direct-metal freeform fabrication technique in which a 200 W fiber laser is used. AISI H13 tool steel is a suitable material for die casting tools because of the high resistance to thermal fatigue and dimensional stability. In this research, AISI H13 tool steel was melted with metal powder by fiber laser. Before melting AISI H13, the powders were analyzed with XRF equipment. Then, hardness distribution of laser melted zone was investigated. The microstructure in laser melted zone was discussed. In order to identify the effect of particle size of powder on the melted zone, two types of particle sizes of powders were used. Experimental results show that the mold repair process using DLMT can be applied in the mold repair industry.

关键词：金属模具应用激光工具钢 H13 社会光纤激光器粉末材料修复过程

Laser surface hardening of AISI H13 tool steel

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中国有色金属学会会刊：英文版 2009年第4期19卷 917-920页

作者： Jae-Ho LEE jeong-Hwan JANG Byeong-Don JOO Young-Myung SON Young-hoon MOON School of Mechanical Engineering Pusan National University

An attempt was made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200 W fiber laser as a heat generating *** hardness of laser melted zone was *** order to identify the effect of heat input on the laser melting zone,scanning conditions were *** results show that,the hardness of as-received AISI H13 tool steel is approximately Hv 240,and the hardness after laser surface heat treatment is around Hv *** hardening depth and width are increased with the increase in the heat input *** of experimental results will be considered in tooling industry.

关键词：激光表面硬化工具钢 H13 激光表面热处理表面硬度信息社会光纤激光器固溶强化

The contribution of gender and age on early and late mortality following ST-segment elevation myocardial infarction： results from the Korean Acute Myocardial Infarction National Registry with Registries

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Journal of Geriatric Cardiology 2018年第3期15卷 205-214页

作者： Ae-Young Her Etm-Seok Shin Yong hoon Kim Scot Garg Myung Ho jeong Division of Cardiology Department of Internal Medicine Kangwon National University School of Medicine Chuncheon South Korea Department of Cardiology Ulsan University Hospital University of Ulsan College of Medicine Ulsan Republic of Korea East Lancashire Hospitals NHS Trust Blackburn Lancashire UK The Heart Center of Chonnam National University Hospital Gwangju Republic of Korea

Background Although previous studies using Korean data have already reported higher rates of mortality in women, it is less clear whether these gender differences in prognosis post ST-segment elevation myocardial infarction （STEMI）, are age dependent. The aim of this study is to examine the gender-age interaction with early and late mortality in patients with STEMI enrolled in the Korean nationwide regis-try. Methods This prospective study stratified outcomes according to gender and age from 17,021 STEMI patients. We compared in-hospital, early （30 days） and late （12 months） mortality between gender to examine the gender-age interaction in multivariable models. Results In younger women （〈 60 years）, in-hospital [5.8% vs. 2.5%, P 〈 0.001; unadjusted odds ratios （OR）： 2.41, 95% confidence inter-vals （CI）： 1.59-3.66], early （6.2% vs. 2.6%, P 〈 0.001; unadjusted OR： 2.4, 95% CI： 2.12-2.72） and late mortality （7.0% vs. 3.1%, P 〉 0.001; unadjusted OR： 2.33, 95% CI： 2.08-2.61） were significantly higher compared with men. However, after adjustment for patient characteristics, Killip class ≥ 3, symptom to balloon time and major bleeding, and in-hospital bleeding, overall early and late mortality were no longer re-lated to gender in any age groups. Conclusions Among a Korean population with STEMI, higher early and late mortality in younger women may be explained by poor patient characteristics, higher Killip class ≥3, longer symptom to balloon time and more frequent major bleeding. Therefore, based on gender-age differences, more precise and aggressive preventive strategies focused on risk factor reduction, education and more intensive management for yotmger women should be performed.

关键词： Age Gender Mortality ST-segment elevation myocardial infarction

Experimental assessment of two-phase bubble pump for solar water heating

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Journal of Central South University 2012年第6期19卷 1590-1599页

作者： CHUNG han-shik WOO Ju-sik SHIN Yong-han KIM Jun-hyo jeong Hyo-min Institute of Marine Industry Department of Mechanical and Precision EngineeringGyeongsang National University445 Inpyeong DongTongyeongGyeongsangnamdo650-160Korea Department of Mechanical and Precision Engineering Gyeongsang National University445 Inpyeong DongTongyeongGyeongsangnamdo650-160Korea Division of Marine Engineering Mokpo National Maritime UniversityHaeyangdaehang-Ro 91Mokpo-siJeollanam-do530-729Korea

The research goal is to develop a new solar water heater system(SWHS) that uses a solar bubble pump instead of an electric *** pump is powered by the steam produced from an evacuated tube ***,heat could be transferred downward from the collector to a hot water storage *** designed system consists of two sets of heat-pipe evacuated tube collectors,a solar bubble pump installed at an upper level and a water storage tank with a heat exchanger at a lower *** heads of 1 and 5 m were *** bubble pump could operate at the collector temperature of about 90-100 ℃ and vapor gage pressure of 80-90 *** is found that water circulation within the SWHS depends on the incident solar intensity and system discharge *** investigations are conducted to obtain the system thermal efficiencies from the hourly,daily and long-term performance *** thermal performance of the proposed system is compared with conventional solar water *** results show that the proposed system achieves system characteristic efficiency of 10% higher than that of the conventional systems using electric pump if taking the consumption of electric power into *** the former is a zero carbon system.

关键词： two-phase bubble pump solar water heater system (SWHS) zero carbon