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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

Effect of organic mineral supplementation in reducing oxidative stress in holstein calves during short‑term heat stress and recovery conditions

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Journal of Animal Science and Biotechnology 2024年第2期15卷 812-825页

作者： A-Rang son Seon-ho Kim Mahfuzul Islam Michelle Miguel Ye Pyae Naing Sang-Suk Lee Ruminant Nutrition and Anaerobe Laboratory Department of Animal Science and TechnologySunchon National UniversitySuncheon 57922Korea Department of Microbiology and Parasitology Sher-e-Bangla Agricultural UniversityDhaka 1207Bangladesh

Background This study investigated the effects of inorganic and organic minerals on physiological responses,oxidative stress reduction,and rumen microbiota in holstein bull calves(123.81±9.76 kg;5 months old)during short-term heat stress(HS)and recovery *** holstein calves were randomly assigned to four treatment groups:no mineral supplementation(Con),inorganic minerals(IM),organic minerals(OM),and high-concentration organic minerals(hoM)and two thermal environments(HS and recovery)using 4×2 factorial arrangement in a crossover design of four periods of 35 *** were maintained in a temperature-controlled *** experimental period consisted of 14 d of HS,14 d of recovery condititon,and a 7-d washing *** Body temperature and respiration rate were higher in HS than in the recovery conditions(PhoM-supplemented calves in both HS(90.38μg/dL)and recovery periods(102.00μg/dL)(PhoM group,which was 5.60 ng/mL lower than in the control group(PhoM group during HS,whereas it was highest in the hoM group(2.58 mmol Trolox equivalent/L)during the recovery period(PhoM supplementation during the HS and recovery periods,whereas SOD and GPX levels were not significantly affected(P>0.05).The principal coordinate analysis represented that the overall rumen microbiota was not influenced by mineral supplementation;however,temperature-induced microbial structure shifts were indicated(PERMANOVA:P<0.05).At the phylum level,Firmicutes and Actinobacteria decreased,whereas Fibrobacteres,Spirochaetes,and Tenericutes increased(P<0.05),under HS *** genus Treponema increased under HS conditions,while Christensenella was higher in recovery conditions(P<0.05).Conc

关键词： Antioxidant status Heat stress holstein bull calves Organic mineral supplementation Oxidative stress

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

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

Effects of Li addition on microstructure and mechanical properties of Mg-6Al-2Sn-0.4Mn alloys

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Transactions of Nonferrous Metals Society of China 2016年第3期26卷 697-703页

作者： Yong-ho KIM Hyeon-Taek son Automotive Component & Materials R&BD Group Korea Institute of Industrial TechnologyGwangju 61012Korea Department of Rare Metals Engineering University of Science & TechnologyDaejeon 34113Korea

Effects of Li addition (2%, 5%, 8% and 11%) on microstructure and mechanical properties of the as-cast and as-extruded Mg?6Al?2Sn?0.4Mn-based alloys were investigated. Mg?xLi?6Al?2Sn?0.4Mn (x= 2, 5, 8 and 11, mass fraction, %) alloys were cast under an SF6 and CO2 atmosphere at 700 °C. After homogenization heat treatment at 350 °C, cast billets were extruded with a reduction ratio of 40:1 at 200 °C. Li addition to Mg?6Al?2Sn?0.4Mn resulted in the formation of MgSnLi2 and MgAlLi2 and/or AlLi intermetallic compounds and random basal texture. With increasing Li addition,β-Li phase was increased and the average area fraction of precipitates increased. Compression yield strength was increased from 212 to 235, 242 and 239 MPa as Li content was increased from 2% to 5%, 8% and 11%, respectively. Elongation was remarkably increased above 60% in 11% Li alloy. It is probable that Li-containing phases play a significant role in the enhanced mechanical properties by Li addition.

关键词： magnesium alloy Li addition extrusion microstructure mechanical property

Electrochemically metal-doped reduced graphene oxide films:Properties and applications

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Journal of Materials Science & Technology 2020年第5期40卷 72-80页

作者： Myung-Sic Chae Tae ho Lee Kyung Rock son Tae hoon Park Kyo Seon Hwang Tae Geun Kim School of Electrical Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841South Korea Department of Clinical Pharmacology and Therapeutics College of MedicineKyung Hee UniversitySeoul 02447South Korea

The fine control of doping levels in graphene materials such as reduced graphene oxide(RGO)is important to properly manipulate their ambipolar transport characteristics for various device ***,conventional doping methods involve complex chemical reactions,large-scale doping processes,and poor ***,a simple and controllable electrochemical doping treatment(EDT),performed via the conductive channels created at the RGO surface by the application of an electric field,is introduced to tailor the electrical properties of RGO films.X-ray photoelectron spectroscopy and Raman spectroscopy measurements are performed to detect the presence of Ni atoms in RGO films after the EDT(EDT-RGO).Then,EDT-RGO field-effect transistors(FETs)are fabricated with different doping areas(0 to 100%fractional area)on the RGO active channel to investigate the effect and selective-area doping capability of the *** to p-type doping compensation by the intercalated Ni atoms,the electron mobility of the EDT-RGO FET decreases from 1.40 to 0.12 cm2 V-1s-1 compared with that of the undoped RGO-FET,leading to the conversion from ambipolar to unipolar p-type transfer characteristics.

关键词： Reduced graphene oxide Electrochemical doping treatment Electrical breakdown process Field-effect transistor

Methylsulfonylmethane suppresses hepatic tumor development through activation of apoptosis

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World Journal of Hepatology 2014年第2期6卷 98-106页

作者： Joo-Hyun Kim Hye-Jun Shin Hye-Lin Ha Young-ho Park Tae-ho Kwon Mi-Ra Jung Hyung-Bae Moon Eun-Sang Cho Hwa-Young son dae-Yeul Yu Aging Research Center Korea Research Institute of Bioscience and Biotechnology College of Veterinary Medicine Chungnam National University Wonkwang University College of Medicine

AIM:To investigate the effect of methylsulfonylmethane(MSM), recently reported to have anti-cancer effects, in liver cancer cells and transgenic mice. METhoDS: Three liver cancer cell lines, HepG2, Huh7-Mock and Huh7-H-rasG12V, were used. Cell growth was measured by Cell Counting Kit-8 and soft agar assay. Western blot analysis was used to detect caspases, poly(ADP-ribose) polymerase(PARP), and B-cell lymphoma2(Bcl-2) expressions. For in vivo study, we administered MSM to H-ras12V transgenic mice for 3 mo. RESULTS: MSM decreased the growth of HepG2, Huh7-Mock and Huh7-H-rasG12V cells in a dose-dependent manner. That was correlated with significantly increased apoptosis and reduced cell numbers in MSM treated cells. Cleaved caspase-8, cleaved caspase-3 and cleaved PARP were remarkably increased in the liver cancer cells treated with 500 mmol/L of MSM; however, Bcl-2 was slightly decreased in 500 mmol/L. Liver tumor development was greatly inhibited in the H-ras12V transgenic mice treated with MSM, compared to control, by showing reduced tumor size and number. Cleaved PARP was significantly increased in non-tumor treated with MSM compared to control. CONCLUSION: Liver injury was also significantly attenuated in the mice treated with MSM. Taken together, all the results suggest that MSM has anti-cancer effects through inducing apoptosis in liver cancer.

关键词： Methylsulfonylmethane Anti-cancer effects Liver cancer cells Transgenic mice Hepatic tumorigenesis

Effects of aqueous extract from red Liriope platyphylla on phthalic-anhydride-induced atopic dermatitis in Interleukin-4/Luciferase/Consensus non-coding sequence-1 transgenic mice evaluated in terms of luciferase signal and general phenotype biomarkers

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Journal of Traditional Chinese Medicine 2017年第4期37卷 475-485页

作者： Moon Hwa Kwak Ji Eun Kim Jun Go hong Joo son Hee Seob Lee Jin Tae hong dae Youn Hwang College of Natural Resources and Life Science/Life and Industry Convergence Research Institute Pusan National UniversityMiryang 627-706South of Korea College of Human Ecology Pusan National UniversityBusan 609-735south of Korea College of Pharmacy and Medical Research Center Chungbuk National UniversityChungju 361-763south of Korea College of Pharmacology Chungbuk National UniversityChungju 361-763south of Korea

OBJECTIVE: To quantitatively evaluate the therapeutic effects of Red Liriope platyphylla(RLP) on atopic dermatitis(AD), alterations in the luciferase(Luc) signal and general phenotype biomarkers were compared in phthalic anhydride(PA) treated Interleukin-4(IL-4)/Luc/Consensus non-coding sequence-1(CNS-1) transgenic(Tg) mice following treatment with aqueous extract of RLP(AEt RLP) for4 ***: Alterations in AD phenotypes were measured in IL-4/Luc/CNS-1 Tg mice following treatment with AEt RLP using inflammation parameter analysis, bioluminescence imaging analysis, histological analysis, reverse transcription-polymerase chain reaction, enzyme linked immunosorbent assay and Western blot ***: RLP contained high concentrations of total phenolic compounds, total flavonoid compounds and 5-HNE related to AD therapy. The Luc signal was only detected in the abdominal region and the submandibular lymph node(SL), mesenteric lymph node(ML), thymus and pancreas of the PA treated group. This signal was significantly decreased by 28%-73% throughout the body and in the four organs in PA + AEt RLP treated group. Furthermore, the lymph node weight, immunoglobulin E concentration and dermal thickness were decreased by 37%-67% in the PA + AEt RLP treated ***: Our findings suggest that the therapeutic effect of AEt RLP on PA induced AD could be successfully quantified by comparison of Luc signals and AD phenotype markers in IL-4/Luc/CNS-1Tg mice, and that the Luc signal was as sensitive as the general AD phenotypes, enabling detection of effects without euthanasia.

关键词： Dermatitis, Atopic Liriope plant Interleukin-4 Luciferases Mice, transgenic Phthalic anhydrides Immunoglobulin E

Kohn–Sham time-dependent density functional theory with Tamm–Dancoff approximation on massively parallel GPUs

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npj Computational Materials 2023年第1期9卷 1556-1567页

作者： Inkoo Kim Daun Jeong Won-Joon son Hyung-Jin Kim Young Min Rhee Yongsik Jung Hyeonho Choi Jinkyu Yim Inkook Jang dae Sin Kim Innovation Center Samsung ElectronicsHwaseong 18448Republic of Korea Department of Chemistry Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Samsung Advanced Institute of Technology Samsung ElectronicsSuwon 16678Republic of Korea

We report a high-performance multi graphics processing unit(GPU)implementation of the Kohn–Sham time-dependent density functional theory(TDDFT)within the Tamm–Dancoff *** algorithm on massively parallel computing systems using multiple parallel models in tandem scales optimally with material size,considerably reducing the computational wall time.A benchmark TDDFT study was performed on a green fluorescent protein complex composed of 4353 atoms with 40,518 atomic orbitals represented by Gaussian-type functions,demonstrating the effect of distant protein residues on the *** the largest molecule attempted to date to the best of our knowledge,the proposed strategy demonstrated reasonably high efficiencies up to 256 GPUs on a custom-built state-of-the-art GPU computing system with Nvidia A100 *** believe that our GPU-oriented algorithms,which empower first-principles simulation for very large-scale applications,may render deeper understanding of the molecular basis of material behaviors,eventually revealing new possibilities for breakthrough designs on new material systems.

关键词： GPUs graphics massive