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차세대 전력반도체 SiC MOSFET의 스위칭 특성 및 효율에 관한 연구
최원묵,안호균,Choi, Won-mook,Ahn, Ho-gyun 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.2
Recently, due to physical limitation of Si based power semiconductor, development speed of switching power semiconductors is falling and it is difficult to expect any further performance improvements. SiC based power semiconductor with superior characteristic than Si-based power semiconductor have been developed to overcome these limitations. however, there is not method to apply for real system. Therefore, suggested the feasibility and solution for SiC-based power semiconductor system. design to 1kW class DC-DC boost converter and demonstrated the superiority of SiC MOSFET under the same operating conditions by analyzing switching frequency, duty ratio, voltage and current, and comparing with Si based power semiconductor through experimental efficiency according to each system load. The SiC MOSFET has high efficiency and fast switching speed, and can be designed with small inductors and capacitors which has the advantage of volume reduction of the entire system. 최근 Si기반 전력반도체의 물성적 한계로 인해 스위칭 반도체의 발전 속도가 떨어지고, 더 이상의 성능향상을 기대하기 어려운 실정이지만 Si기반보다 우수한 물성을 가진 SiC 기반 전력반도체가 개발되고 있다. 하지만 실제 시스템에 적용하기 위해서는 아직 뚜렷한 방법이 제시되지 못하고 있다. SiC기반 전력반도체의 시스템 설계에 대한 타당성과 솔루션을 제안하기 위하여, 1kW급의 DC-DC컨버터를 설계 및 제작하고 스위칭 주파수, 듀티비, 전압, 전류의 변화 조건 속에서 Si기반 전력반도체와 실험을 통해 비교 분석하였다. 각 시스템 부하별 입․출력을 통한 효율을 분석 및 Si MOSFET 대비 SiC MOSFET의 우수한 스위칭 성능을 확인하였고, 이를 통해 동일한 구동 조건에서 SiC MOSFET의 우수성을 검증하였다.
포스트 코로나 시대의 가상화재대피훈련을 위한 열방출율에 관한 연구
강은혜(Kang, Eun-Hye),최원묵(Choi, Won-Mook),김순호(Kim, Soon-Ho),최정민(Choi, Jeong-Min) 대한건축학회 2020 대한건축학회 학술발표대회 논문집 Vol.40 No.2
Recently, social interest in measures to prevent fires has been increasing due to fires that have caused great damage to people, such as the fire at the Icheon Logistics Center. However, due to the corona 19 virus that started in Wuhan, China, people are crowded and they are refraining from engaging in face-to-face activities. It is required a virtual fire evacuation drill which is a non-face-to-face through the fire simulation, which is a computer program. In the fire simulation, it has not yet been established for quantitative fire characteristics such as the heat release rate, the location of the fire, and the fire growth rate. So, the input variables of the fire simulation are selectively implemented at the discretion of the user, resulting in different results for each user. And the size of the building and the openings are not reflected, and the heat release rate has not been calculated in consideration of flashover. Therefore, in this study, the heat release rate that is expected to occur flashover is calculated though the theoretical equations considering the ventilation factor in NFPA. Finally, it is provided the basic data for virtual fire evacuation drill of the Available Safe Egress Time considering the size and opening the building.
동적 CT와 MRI에서 진단이 엇갈리는 간암의 치료로서 고주파열치료와 경동맥화학색전술의 효과 비교
조영윤 ( Young Youn Cho ),권정희 ( Jung Hee Kwon ),이정훈 ( Jeong Hoon Lee ),이정민 ( Jeong Min Lee ),이재영 ( Jae Young Lee ),김효철 ( Hyo Cheol Kim ),정진욱 ( Jin Wook Chung ),최원묵 ( Won Mook Choi ),조은주 ( Eun Ju Cho ),유수 대한간암학회 2015 대한간암학회지 Vol.15 No.1
Background/Aims: This study compared the outcomes of patients with small hepatocellular carcinomas (HCCs) who were treated using transarterial chemoembolization (TACE) or radiofrequency ablation (RFA). Methods: This was a post-hoc analysis of a prospective study that evaluated the diagnostic efficacy of magnetic resonance imaging (MRI) and computed tomography (CT). We analyzed 41 small hepatic nodules in 32 patients that showed typical radiologic hallmarks on both CT and gadoxate-enhanced MRI (typical nodules) and 25 small hepatic nodules from 22 patients that showed atypical radiologic hallmarks on CT and typical radiologic hallmarks on MRI (discrepant nodules). Results: There were no significant differences in the baseline characteristics of the patients with typical and discrepant nodules. Complete response rates 1 month after TACE or RFA were 75.0% (18/24) and 94.1% (16/17; P=0.20), respectively, for the patients with typical nodules and 58.8% (10/17) and 100% (8/8; P=0.05), respectively, for the patients with discrepant nodules. Treatment failure rates after TACE or RFA were 33.3% (8/24) and 5.8% (1/17; P=0.15), respectively, for the patients with typical nodules and 47.0% (8/17) and 0.0% (0/8; P=0.02), respectively, for the patients with discrepant nodules. Among patients achieving complete response, there were no significant differences in the risk of marginal recurrence.
증례 : 소화기 ; 크론병 환자에서 발생한 간세포암 1예
장승현 ( Seung Hyeon Jang ),김지현 ( Jee Hyun Kim ),이재우 ( Jae Woo Lee ),이준영 ( June Young Lee ),조영윤 ( Young Youn Cho ),최원묵 ( Won Mook Choi ),정현채 ( Hyun Chae Jung ) 대한내과학회 2015 대한내과학회지 Vol.88 No.4
간세포암은 주로 간경화증이나 바이러스 간염 등의 만성간 질환을 가진 환자에서 발생하며 기저에 만성 간 질환이 없는 크론병 환자에서 간세포암이 발생하는 경우는 극히 드물다. 지금까지 보고된 몇몇 국외의 증례들을 살펴보면 비교적 젊은 나이에 크론병이 발생하여 크론병의 유병 기간이 길고 azathioprine을 포함한 면역억제제를 장기간 사용하였다. 만성 간 질환이 없던 34세 남자 크론병 환자가 14년간아자티오프린 치료 및 반복적인 수술을 받았다. 추적 관찰하던 중 결장 천공과 결장 주위 농양으로 입원하였고 당시 시행한 전산화 단층촬영에서 결장 천공과 간의 종양이 발견되었다. 간의 종양은 간 조직 검사에서 기저에 간경화증 등의 특별한 병리학적 소견 없이 간세포암이 확인되었다. 결장 주위 농양과 결장 천공에 대해 우측 결장 절제술을 시행하였고 간세포암에 대해 간동맥 화학색전술 및 고주파 열치료를 시행하였다. 본 증례는 국내에서는 처음 보고되는 증례로 이전 보고되었던 증례와는 달리 원발성 경화성담관염이나 국소적 간 글리코겐증 등의 병리학적 소견을 보이지 않았다. 저자들은 만성 간 질환이 없는 크론병 환자에서 간세포암이 발생한 드문 증례를 문헌고찰과 함께 보고하는 바이다. Hepatocellular carcinomas (HCCs) in patients with Crohn`s disease (CD) without underlying chronic hepatitis or liver cirrhosis are extremely rare. Previously reported cases occurred in patients who had developed CD at a young age and had been treated with immunosuppressive agents long-term. We herein report the first case of HCC in a 34-year-old patient with CD in Korea. The patient was treated with azathioprine for 14 years and had undergone repeated surgeries for CD. During the follow-up period, the patient was hospitalized for colon perforation and pericolic abscess formation. Computed tomography showed a liver mass, and HCC was diagnosed based on liver biopsy. The patient underwent right hemicolectomy for colon perforation and transcatheter arterial chemoembolization followed by radiofrequency ablation for the HCC. The present case is similar to previously reported cases with the exception of the liver pathology findings, which exhibited neither primary sclerosing cholangitis nor focal hepatic glycogenolysis.