http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
최정철,장세훈,차용훈,오익현,Choi, Jung-Chul,Chang, Se-Hun,Cha, Young-Hoon,Oh, Ik-Hyun 한국재료학회 2009 한국재료학회지 Vol.19 No.7
In this study, Ti powder was fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method. Hydrogenation reactions of Ti scrap occurred at near 450 $^{\circ}C$ with a sudden increase in the reaction temperature and the decreasing pressure of hydrogen gas during the hydrogenation process in the furnace. The dehydrogenation process was also carried out at 750 $^{\circ}C$ for 2hrs in a vacuum of $10^{-4}$ torr. After the HDH process, a deoxidation treatment was carried out with the Ca(purity: 99.5) at 700 $^{\circ}C$ for 2hrs in the vacuum system. It was found that the oxidation content of Ti powder that was deoxidized with Ca showed noticeably lower values, compared to the content obtained by HDH process. In order to fabricate Ti compacts, Ti powder was sintered at $1100\sim1400^{\circ}C$ for 2hrs under a vacuum of $10^{-4}$ torr. The relative density of compact was 94.9% at 1300 $^{\circ}C$. After sintering, all of the Ti compacts showed brittle fracture behavior, which occurred in an elastic range with short plastic yielding up to a peak stress.
최정철,장세훈,차용훈,오익현,Choi, Jung-Chul,Chang, Se-Hun,Cha, Young-Hoon,Oh, Ik-Hyun 한국재료학회 2009 한국재료학회지 Vol.19 No.2
In this study, Ti powder was fabricated from Ti scrap by a hydrogenation-dehydrogenation (HDH) method. The Ti powders were compacted by Spark plasma sintering (SPS) and the microstructure and mechanical properties of the powders were investigated. A hydrogenation reaction of Ti scrap occurred at temperatures near $450^{\circ}C$ with a sudden increase in the reaction temperature and a decrease in the pressure of the hydrogen gas as measured in a furnace during the hydrogenation process. In addition, a dehydrogenation process was carried out at $750^{\circ}C$ for 2hrs in a vacuum of $10^{-4}torr$. The Ti powder sizes obtained by hydrogenation-dehydrogenation and mechanical milling processes were in the range of $1{\sim}90{\mu}m$ and $1{\sim}100{\mu}m$, respectively. To fabricate Ti compacts, Ti powders were sintered under an applied uniaxial punch pressure of 40 MPa at in a range of $900{\sim}1200^{\circ}C$ for 5 min. The relative density of a SPSed compact was 99.6% at $1100^{\circ}C$, and the tensile strength decreased with an increase in the sintering temperature. However, the hardness increased as the sintering temperature increased.
방전플라즈마소결법을 이용한 WC-3 wt%Co 소결체 제조 및 평가
최정철,장세훈,차용훈,오익현,Choi, Jung-Chul,Chang, Se-Hun,Cha, Young-Hoon,Oh, Ik-Hyun 한국재료학회 2008 한국재료학회지 Vol.18 No.7
Microstructure and mechanical properties of WC-3 wt% Co cemented carbides, fabricated by a spark plasma sintering (SPS) process, were investigated in this study. The WC-3 wt%Co powders were sintered at $900{\sim}1100^{\circ}C$ for 5min under 40MPa in high vacuum. The density and hardness were increased as the sintering temperature increased. WC-3 wt%Co compacts with a relative density of 97.1% were successfully fabricated at $1100^{\circ}C$. The fracture toughness and hardness of a compact sintered at $1100^{\circ}C$ were $21.6 MPa{\cdot}m^{1/2}$ and 4279 Hv, respectively.
한국인 결합조직병에서 자가항체의 양성율에 관한 연구 - 홍반성 루푸스 , 피부근염 , 경피증 환자를 중심으로 -
최정철(Jung Chul Choi),장성은(Sung Eun Chang),최지호(Jee Ho Choi),성경제(Kyung Jeh Sung),문기찬(Kee Chan Moon),고재경(Jai Kyoung Koh) 대한피부과학회 2001 대한피부과학회지 Vol.39 No.5
N/A Background: Serologic test is important in the evaluation of patients with connective tissue diseases(CTD). It does help to confirm a clinical diagnosis, classify subsets of CTD and predict prognosis. In Korean patients with various CTD, the positive rate of each autoantibody has not been reported in dermatologic literatures. Objectives: The purpose of this study was aimed at investigating the positive rate of autoantibodies in Korean patients with CTD. Patients and Methods: The 173 patients who visited the dermatologic clinic of A san medical center from 1995 to 2000 were diagnosed as having systemic lupus erythematosus(SLE), discoid lupus erythematosus(DLE), dermatomyositis or scleroderma. Fifty eight patients of SLE, 35 patients of DLE, 34 patients of dermatomyositis and 46 patients of scleroderma were enrolled. Using the sera from the total 173 patients, the presence of antinuclear antibody(ANA) was detected by an indirect immunofluorescence test using cultured human cell substrates(HEp-2 cells). The presence of extractable nuclear antigen(RNP, Sm, Ro(SS-A), La(SS-B), Scl-70, Jo-1) was detected by gel double immunodiffusion. Anti-double-stranded DNA(dsDNA) was detected by radioimmunoassay. Results: l. Of the 58 patients with SLE, the sera of 56 patients(96%) was positive to ANA. Thirty four patients(58%) had anti-dsDNA antibodies. Thirteen patients(22%) had anti-RNP antibodies. Twenty nine patients(50%) had anti-Ro(SS-A) antibodies while 5 patients(8%) had anti-La(SS-B) antibodies. Only 5 patients(8%) had anti-Sm antibodies. 2. Of the 35 patients with DLE, the sera of 17 patients(48%) was positive to ANA. Among 10 patients tested, only one patient(10%) had anti-RNP antibodies. Two patients(20%) had both anti-Ro(SS-A) and anti-La(SS-B) antibodies. 3. Of the 34 patients with Dermatomyositis, the sera of 16 patients(47%) was positive to ANA. Among 13 patients tested, one patient(7%) had anti-dsDNA antibody. Among 20 patients tested, two patients(10%) had anti-Ro(SS-A) antibodies. Two patients(10%) had anti-Jo-1 antibodies. 4. Of the 46 patients with scleroderma, the sera of 24 patients(52%) was positive to ANA. Among 12 patients tested, two patients(16%) had anti-dsDNA antibodies. Among 30 patients tested, nine patients(30%) had anti-Scl-70 antibodies. Conclusions . In Korean patients with CTD, the positive rate of various autoantibodies were similar to the previous western reports except some minor differences; (1) lower positive rate of anti-Sm and higher positive rate of anti-Ro(SS-A) in SLE. (2) lower positive rate of anti-Jo-1 in dermatomyositis. (3) higher positive rate of anti-Scl-70 in scleroderma. 2. SLE patients have significantly higher percentage of ANA, anti-dsDNA, anti-RNP, anti-Sm, anti-Ro(SS-A) antibodies in compared to DLE, dermatomyositis, and scleroderma patients.
방전플라즈마 소결공법에 의해 제작된 SOFC용 Ni-YSZ Anode의 특성평가
장세훈,최정철,최세원,김호성,오익현,Chang, Se-Hun,Choi, Jung-Chul,Choi, Se-Weon,Kim, Ho-Sung,Oh, Ik-Hyun 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.5
SOFC (Solid Oxide Fuel Cell) Ni-YSZ anode was fabricated by the spark plasma sintering (SPS) process and its microstructure and electrical properties were investigated in this study. The spark plasma sintering process was carried out at $800{\sim}1000^{\circ}C$ for holding time of 5 min under 40 MPa. To fabricate Ni-YSZ anode, the SPS processed specimens were reduced at $800^{\circ}C$ under $H_2$ atmosphere. The reduced specimens showed relative density of $48.4{\sim}64.8%$ according to sintering temperature. And also, the electrical conductivity of reduced specimens after sintering at 900 and $1000^{\circ}C$ showed $480{\sim}600$ (S/cm) values at the measuring range of $600{\sim}900^{\circ}C$.
티타늄 스크랩을 이용한 분말제조 및 소결 성형체의 특성평가
이승민,최정철,박현국,우기도,오익현,Lee, Seung-Min,Choi, Jung-Chul,Park, Hyun-Kuk,Woo, Kee-Do,Oh, Ik-Hyun 한국재료학회 2010 한국재료학회지 Vol.20 No.3
In this study, Ti powders were fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method. The Ti powders were prepared from the spark plasma sintering (SPS) and their microstructure was investigated. Hydrogenation reactions of Ti scrap occurred at near $450^{\circ}C$ with a sudden increase in the reaction temperature and the decreasing pressure of hydrogen gas during the hydrogenation process in the furnace. The dehydrogenation process was also carried out at $750^{\circ}C$ for 2 hrs in a vacuum of $10^{-4}$ torr. After the HDH process, deoxidation treatment was carried out with the Ca (purity: 99.5%) at $700^{\circ}C$ for 2 hrs in the vacuum system. It was found that the oxidation content of Ti powder that was deoxidized with Ca showed noticeably lower values, compared to the content obtained by the HDH process. In order to fabricate the Ti compacts, Ti powder was sintered under an applied uniaxial punch pressure of 40 MPa in the range of $900-1200^{\circ}C$ for 5 min under a vacuum of $10^{-4}$ torr. The relative density of the compact was 99.5% at $1100^{\circ}C$ and the tensile strength decreased with increasing sintering temperature. After sintering, all of the Ti compacts showed brittle fracture behavior, which occurred in an elastic range with short plastic yielding up to a peak stress. Ti improved the corrosion resistance of the Ti compacts, and the Pd powders were mixed with the HDH Ti powders.
스퍼터링 타겟재의 응용을 목적으로 하는 탄탈륨 소결체의 제작 및 평가
장세훈,최정철,최세원,오익현,Chang, Se-Hun,Choi, Jung-Chul,Choi, Se-Weon,Oh, Ik-Hyun 한국재료학회 2008 한국재료학회지 Vol.18 No.4
In this study, tantalum (Ta) compacts were fabricated in a spark plasma sintering (SPS) process and their microstructure and mechanical properties were investigated. Ta compacts with a density of 99% were successfully fabricated by controlling the sintering conditions of the current and the temperature. The density and hardness were increased as the sintering temperature increased. The $Ta_2C$ compound was observed at the surface of the compacts due to the contact between the Ta powder and graphite mold during the sintering process. The main fracture mode showed a mixed type with intergranular and transgranular modes having some roughness.
신현창,김철,최정철,최승철,Shin, Hyun-Chang,Kim, Chul,Choi, Jung-Chul,Tsuji, Masamichi,choi, Seung-Chul 한국에너지학회 1999 에너지공학 Vol.8 No.1
지구 온난화 현상의 주된 원인인 CO2 가스의 분해를 위해, 스트론튬 페라이트를 이용한 CO2 가스 분해 반응에 대해 연구하였다. CO2 가스 분해를 위한 반응 매체로 스피넬형 조성과 마그네토프롬바이트형 조성의 스트론튬 페라이트 미세분말을 공침법으로 제조한 후, H2 가스로 환원시켜 산소부족형 스트론튬 페라이트 분말을 제조하였다. 이 산소부족형 스트론튬 페라이트 분말은 CO2 가스를 환원, 분해시키면서 산화된다. 이러한 원리를 이용한 CO2 분해 반응에서 스피넬형 조성 스트론튬 페라이트 분말이 마그네토프롬바이트형 조성 분말 보다 빠르게 많은 양의 CO2 가스를 분해 시켰다. 페라이트 중의 스트론튬이 산화·환원 반응을 촉진시키는 것을 관찰할 수 있었다.