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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

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

Flow characteristics of aluminum coated boron steel in hot press forming

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中国有色金属学会会刊：英文版 2009年第4期19卷 913-916页

作者： Jeong-Hwan JANG Jae-Ho LEE Bye ong-Don JOO young-hoon moon School of Mechanical Engineering Pusan National University

The flow characteristics of aluminum coated boron steel in hot press forming were ***,the effects of aluminum coated layer on press forming were analyzed during deep *** results show that aluminum coated boron steel exhibits a high sensitivity on temperature and strain *** coating layer appears in surface flaking in a temperature range of 700-800 ℃,but smooth surface is formed above 900 ℃.

关键词：热压成型流动特性铝涂层硼钢表面剥落温度范围冲压成形高灵敏度

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B9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

Experimental investigation of friction coefficient in tube hydroforming

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 194-198页

作者： Hyae Kyung YI Hong Sup YIM Gun Yeop LEE Sung Mun LEE Gi Suk CHUNG young-hoon moon Engineering Research Center for Net Shape and Die Manufacturing School of Mechanical Engineering Pusan National University Technical Research laboratories POSCO Jeonnam 545-090 Korea

The friction coefficient between tube and die in guide zone of tube hydroforming was obtained. In hydroforming, the tube is expanded by an internal pressure against the tool wall. By pushing the tube through tool, a friction force at the contact surface between the tube and the tool occurs. In guiding zone, the friction coefficients between tube and die can be estimated from the measured axial feeding forces. In expansion zone, the friction coefficients between tube and die can be evaluated from the measured geometries of expanded tubes and FE analysis.

关键词：内高压成形摩擦系数实验有限元分析液压成形内部压力轴向进给几何尺寸

Tailoring strength-ductility balance of caliber-rolled AZ31 Mg alloy through subsequent annealing

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Journal of Magnesium and Alloys 2020年第1期8卷 163-171页

作者： Taein Kong Byung Je Kwak Jonghyun Kim Jeong Hun Lee Sung Hyuk Park Ji hoon Kim young hoon moon Hyun Sik Yoon Taekyung Lee School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea Advanced Forming Process R&D Group Korea Institute of Industrial TechnologyUlsan 44413Republic of Korea College of Materials Science and Engineering Chongqing UniversityChongqing 400044China School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Naval Architecture and Ocean Engineering Pusan National UniversityBusan 46241Republic of Korea

Recently,multi-pass caliber rolling has been shown to be effective for Mg *** study investigated the effect of subsequent annealing on the mechanical properties of a caliber-rolled AZ31 Mg alloy to modulate the strength-ductility *** annealing gave rise to different trends in mechanical properties depending on the temperature ***-temperature annealing(T≤473 K)exhibited a typical trade-off relationship,where an increase in annealing temperature resulted in increased ductility but decreased strength and *** a heat treatment did not degrade the high strength-ductility balance of the caliber-rolled alloy,suggesting that the mechanical properties could be tailored for different potential *** contrast,high-temperature annealing(T>473 K)caused a simultaneous deterioration in strength,hardness,and ductility with increasing annealing *** differences are discussed in terms of the varying microstructural features under the different investigated annealing regimes.

关键词： AZ31 Mg alloy Caliber rolling Annealing Grain growth Mechanical improvement Twinning

Trends in colorectal cancer incidence according to an increase in the number of colonoscopy cases in Korea

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World Journal of Gastrointestinal Oncology 2024年第1期16卷 51-60页

作者： Ga Hee Kim Yeong Chan Lee Tae Jun Kim Sung Noh Hong Dong Kyung Chang young-Ho Kim Dong-hoon Yang Chang Mo moon Kyunga Kim Hyun Gun Kim Eun-Ran Kim Division of Gastroenterology Department of Internal MedicineAsan Medical CenterUniversity of Ulsan College of MedicineSeoul 05505South Korea Department of Digital Health Samsung Advanced Institute for Health Science and TechnologySungkyunkwan University School of MedicineSeoul 06351South Korea Division of Gastroenterology Department of Internal MedicineSamsung Medical CenterSungkyunkwan University School of MedicineSeoul 06351South Korea Division of Gastroenterology Department of Internal MedicineEwha Womans UniversitySeoul 07985South Korea Biomedical Statistics Center Samsung Medical CenterSeoul 06351South Korea Division of Gastroenterology Department of Internal MedicineSoonchunhyang University College of MedicineSeoul 04401South Korea

BACKGROUND The incidence of colorectal cancer(CRC)and preinvasive CRC(e.g.,early colon cancer and advanced adenoma)is gradually increasing in several *** To evaluate the trend in incidence of CRC and preinvasive CRC according to the increase in the number of colonoscopies performed in *** This retrospective cohort study enrolled Korean patients from 2002 to 2020 to evaluate the incidence of CRC and preinvasive CRC,and assess the numbers of diagnostic colonoscopies and colonoscopic ***-related complications by age group were also *** The incidence of CRC showed a rapid increase,then decreased after 2012 in the 50-75 year-age *** the study period,the rate of incidence of preinvasive CRC increased at a similar level in patients under 50 and 50-75 years of *** 2009,the increase has been rapid,showing a pattern similar to the increase in *** rate of colonoscopic polypectomy in patients aged under 50 was similar to the rate in patients over 75 years of age after *** rate of complications after colonoscopy and related deaths within 3 mo was high for those over 75 years of *** The diagnosis of preinvasive CRC increased with the increase in the number of colonoscopies *** the risk of colonoscopy-related hospitalization and death is high in the elderly,if early lesions at risk of developing CRC are diagnosed and treated under or at the age of 75,colonoscopy-related complications can be reduced for those aged 76 years or over.

关键词： Colorectal cancer Preinvasive colorectal cancer Colorectal polypectomy Colonoscopy

Porocarcinoma in a palm reconstructed with a full thickness skin graft: A case report

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World Journal of Clinical Cases 2024年第3期12卷 665-670页

作者： Seok Beom Lim Kun young Kwon hoon Kim Soo Yeon Lim In Chang Koh Department of Plastic and Reconstructive Surgery Konyang University Medical CenterKonyang University of College of MedicineDaejeon 35365South Korea Department of Pathology Konyang University Medical CenterKonyang University of College of MedicineDaejeon 35365South Korea

BACKGROUND Porocarcinoma is a rare type of skin cancer that originates from sweat gland *** is an aggressive malignant skin cancer that is difficult to diagnose clinically owing to its rarity and similarity to squamous cell carcinoma(SCC).CASE SUMMARY This case involved a 92-year-old woman,a farmer by profession,presented with an exophytic and verrucous mass on her left palm that had formed 2 years prior and caused chronic pain and frequent ***,the patient was diagnosed with SCC using a punch biopsy;however,a repeat biopsy with addi-tional immunohistochemical tests was performed for ***,the patient was diagnosed with porocarcinoma and reconstruction was planned using a full-thickness skin *** treatment,the range of motion of the palm was preserved,and the aesthetic outcome was *** 6 mo of follow-up,the patient was satisfied with the *** Porocarcinoma is commonly misdiagnosed as SCC;therefore,clinicians should consider porocarcinomas when evaluating mass-like lesions on the hands.

关键词： Eccrine porocarcinoma Hand defects Reconstructive surgery Sweat gland tumor Skin graft Case report

Production of chitosan-based composite film reinforced with lignin-rich lignocellulose nanofibers from rice husk

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Journal of Bioresources and Bioproducts 2024年第2期9卷 174-184页

作者： Hye Jee Kang Yeon Ju Lee Jin Kyoung Lee Irnia Nurika Sri Suhartini Deokyeong Choe Dong Hyun Kim hoon Choi Natasha P.Murphy Ho Yong Kim young hoon Jung School of Food Science and Biotechnology Kyungpook National UniversityDaegu 41566Republic of Korea CPR S&T Co. Ltd.Gunpo 15880Republic of Korea Department of Agroindustrial Technology Faculty of Agricultural TechnologyUniversitas BrawijayaMalang 65145Indonesia Renewable Resources and Enabling Sciences Center National Renewable Energy LaboratoryGoldenCO 80401United States Center for Bio-based Chemistry Korea Research Institute of Chemical TechnologyUlsan 44429Republic of Korea

Lignocellulosic nanofibers(LCNFs),implying lignin-containing cellulose fibers,maintain the prop-erties of both lignin and cellulose,which are hydrophobic and hydrophilic,*** pres-ence of hydrophobic lignin in LCNFs is expected to be an economical and attractive option that can improve the thermal and mechanical properties of ***,this study was conducted to produce lignin-rich LCNFs from sugar-rich waste obtained from rice husks after acidic *** LCNFs were produced from the lignin-rich solid fractions obtained after pretreatment and enzymatic hydrolysis,which were then incorporated as an additive into a chitosan-based *** variations in lignin content in the range of approximately 50.6%-66.8%in differently obtained LCNFs gave significantly different optical strengths and mechanical *** controllable processes may allow for customized film ***,the glucose-rich liquid fractions obtained after pretreatment and enzymatic hydrolysis were used as a substrate for ethanol fermentation to achieve total utilization of rice husk biomass *** conclusion,the lignin-rich biomass fraction holds promise as a suitable material for chitosan-LCNF film and has the potential to increase the economic feasibility of the biomaterial industry.

关键词： Rice husk Lignocellulose nanofiber Lignin-based material Chitosan film Upcycling