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AlN-Al<sub>2</sub>O<sub>3</sub> 계에서의 상압소결 질화물복합체
김영우,김규헌,김동현,윤석영,박홍채,Kim, Young Woo,Kim, Kyu Heon,Kim, Dong Hyun,Yoon, Seog Young,Park, Hong Chae 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
Particulate nitride composites have been fabricated by sintering the compacted powder of AlN and 5 - 64.3 mol% $Al_2O_3$, with a small addition of $Y_2O_3$ ($Y_2O_3$/AlN, 1 wt%), in 1-atm nitrogen gas at $1650-1900^{\circ}C$. The composites were characterized in terms of sintering behavior, phase relations, microstructure and thermal shock resistance. AlN, 27R AlN pseudopolytype, and alminium oxynitride (AlON, $5AlN{\cdot}9Al_2O_3$) were found to existin the sintered material. Regardless of batch composition, the AlN-$Al_2O_3$ powder compacts exhibited similar sintering behavior; however, the degree of shrinkage commonly increased with increasing $Al_2O_3$ content, consequently giving high sintered bulk density. By increasing the $Al_2O_3$ addition up to ${\geq}50 mol%$, the matrix phase in the sintered material was converted from AlN or 27R to AlON. Above $1850^{\circ}C$, a liquid phase was formed by the reaction of $Al_2O_3$ with AlN, aided by $Y_2O_3$ and mainly existed at the grain boundaries of AlON. Thermal shock resistance was superior in the sintered composite consisting of AlON with dispersed AlN or AlN matrix phase.
김영우,유도성,김달수,허필우,조경석,김재건,강준기,Kim, Young-Woo,Yoo, Do-Sung,Kim, Dal-Soo,Huh, Pil-Woo,Cho, Kyung-Suck,Kim, Jae-Gun,Kang, Joon-Ki 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.2
Objective : Cranioplasty is required to protect underlying brain, to correct major aesthetic deformities, or both. The ideal material for this purpose is autogenous bone. When this is not available, alloplastic or artificial materials may be used. In this study authors compared the infection rate according to the cranioplasty materials(the frozen autologous bone vs. bone cement), and duration of the skull defect. Materials : Between May 1994 and December 1999, 111 patients with skull defect treated with cranioplasty(82 cases of frozen autologous bone and 29 cases of artificial bone material) were included in this study. There were 77 males and 34 females with a mean age of 41.4 years(range 1-85 years). 57 patients had head trauma and 54 had non-traumatic insults. According to the duration of skull defect, there were 28 cases under 1 month, 33 cases of 1-2 months, 15 cases of 2-3 months, 20 cases of 3-6 months and 15 cases over 6 months of duration. Results : Overall infection rate was 9.9%. In cases with frozen autologous bone and artificial bone material, the infection rate was 8.5% and 13.7%, respectively. The infection rate according to the duration of skull defect was 3.6%(among 28 cases) under 1 month of age, while those were 12%(4 among 33 cases) at 1-2 months, 20%(3 among 15 cases) at 2-3 months, 5%(1 among 20 cases) at 3-6 months and 13%(2 among 15 cases) over 6 months. Accoring to the underlying disease, the infection rate in traumatic cases was 12%(7 among 57 cases) and that in non-traumatic one was 3.7%(2 among 54 cases). Conclusion : From this study, it appears that skull defect should be repaired as soon as possible, because early cranioplasty can lower the infection rate. And surgeons could save the patients' cranial bone as possible as they can because autologous bone is not only cost effective in cosmatic purpose but lower the infection rate.
고령에서 발현한 척수외 혈관모세포종 - 증 례 보 고 -
김영우,김재건,유도성,허필우,조경석,김달수,강준기,Kim, Young Woo,Kim, Jae Keon,Yoo, Do Sung,Huh, Phil Woo,Cho, Kyuong Suck,Kim, Dal Soo,Kang, Joon Ki 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.2
Intradural extramedullary hemangioblastoma of the spinal cord is uncommon tumor. Symptom onset is typically in the forth decade. Complete excision offers the best chance for cure. We report a case of extramedullary hemangioblastoma of the spinal cord in old age. A 76 -year old man presented with 1 month history of paraparesis. Multiple enhancing lower thoracic and lumbar spinal masses were seen on magnetic resonance imaging(MRI). Surgical exploration for symptomatic lesion revealed intradural-extramedullary mass, which had hypervascularity. The excised spinal masses were diagnosed as hemangioblastoma. Postoperative course was uneventful and symptoms improved gradually.
김영우,황영하,임용진,김도향,홍준표,Kim, Y.W.,Kwang, Y.H.,Lim, Y.J.,Kim, D.H.,Hong, C.P. 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.1
The softening behavior of squeeze cast Mg-Li-Al and Mg-Li-Al-Zr alloys have been investigated. The highest hardness values of Mg-Li-Al and Mg-Li-Al-Zr alloys were obtained after solution treatment at $400^{\circ}C$ for 1 hour. The hardness value, however, decreased as the aging temperature and time increased. Microstructural and calorometric analyses showed that quenched-microstructure changed from primary (${\alpha}$ and ${\beta}$)+secondary ${\alpha}$ to primary(${\alpha}$ and ${\beta}$)+secondary ${\alpha}+{\theta}$ after aging. The softening during aging was due to the coarsening of ${\theta}$ precipitates.
김영우,김주혜,Kim. Youngwoo,Kim. Joohae 팬코리아영어교육학회(구 영남영어교육학회) 2015 영어교육연구 Vol.27 No.2
With the increased need for English in the Korean society, ELT programs need to expand as well. In order to examine whether these needs are being met through academic efforts, the trends in ELT programs and curricula in ELT academic journals published in Korea from 2000 to 2014 were analyzed. Eleven ELT-related academic journals were selected from the indexed journal list of the National Research Foundation in Korea. From the 5,486 articles that have been published, relevant articles were selected using keywords appropriate to the study of ELT programs and curricula. Four hundred and twenty articles were finally selected and then analyzed according to journal, publication year, target institutions, program type, and relevance to the curriculum. The results showed that many articles focus on English programs and curricula at the college level. English programs and curricula in primary schools are another area of focus. Only a few articles address ELT programs and curricula in the middle and high school contexts. ELT teacher training programs were another favorite area of research interest. Some articles discussed the ELT curriculum itself, while others studied topics such as ELT textbooks in the context of the ELT curriculum. Although there have been numerous ELT activities in the private sector in Korea, such as private tutoring, educational institutions (hagwons), and online ELT services, research related to these is seldom found in journal articles. Overall, research on ELT programs and curricula in Korea seems to be carried out according to ELT researchers’ own interests or professional convenience, along with changes in the Korean national curriculum. Some implications from the results of the study are discussed at the end.
김영우,김성운,Kim, Y.W.,Kim, S.W. 한국전자통신연구원 2010 전자통신동향분석 Vol.25 No.5
반도체 공정 기술의 발전으로 인하여 반도체 회로는 지속적으로 비약적인 성능의 발전을 가져오고 있다. 고성능 프로세서는 이와 같은 반도체 공정의 미세화에 따라 전력소모 및 발열 문제로 인하여 공정 및 속도 향상을 통한 성능 경쟁에서 탈피하여, 수십 개에서 수백 개의 코어를 내장하는 고도병렬화/이기종화를 통한 성능 향상을 추구하는 시대로 접어들고 있다. 본 문서에서는 최근의 고성능 프로세서 동향을 중심으로 병렬/이기종화 기술 및 관련 기술의 최근 동향과 향후 발전 추세에 대해 논의하고자 한다.