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문채주,김홍렬,조병수 木浦大學校 工業技術硏究所 1999 工業技術硏究誌 Vol.9 No.-
As applications of digital system are increasing in nuclear power industry, there are increasing on importance of their reliability assessment. This paper describes definition, analysis methods and procedure of reliability for digital system in terms of hardware. The reliability analysis is classified as qualitative method and quantitative method. This paper presents a representative qualitative method, FMEA, and three quantitative methods, Reliability Block Diagram, Fault Event Trees, Markov state Transition Method, which can be applicable in power plant. The comparisons of three quantitative methods are presented for analyst to select a suitable method according to environments of applications. The procedure is also presented for systematic safety and reliability analysis of digital system. Each step of the procedure is described in terms of objective, necessity, method and consideration.
홍창우,김태경,김경진,김성환,김남윤,심도식,이정호,윤청호,백민경,원치문,박제선,이주형,정경일 강원대학교 석재복합신소재제품연구센터 1996 석재연 논문집 Vol.1 No.-
콘크리트 구조물이 대형화됨에 따라 설계단면이 증대되어 상대적으로 많은 경제적 손실을 부담하게 된다. 따라서 단면을 감소시키면서도 소요의 하중에 안전한 구조물을 건설하기 위해서는 우선적으로 구조물 건설에 기초가 되는 고품질, 고내구성의 고강도 콘크리트 개발이 절실히 요구된다 본 연구에서는 일정 시멘트비 및 혼화재 비율하에서 소요의 워커빌리티가 확보되는 고강도 콘크리트를 시간과 온도의 변화에 따라 증기 양생하여, 압축, 인장, 휨강도 뿐만 아니라 파괴특성을 실험적으로 연구하였다. 시료 제작시 시멘트 입자 사이의 공극 및 불연속 영역을 충전하여 고밀도화하기 위한 콘크리트용 혼화재로 시멘트 비표면적이 상당히 작은 초미립 분말인 실리카흄을 이용하였다. 또한 AE감수제 및 고성능 유동화제를 사용하여 혼화재의 첨가에 의하여 발생될 수 있는 워커빌리티의 감소를 방지하였다. 실험결과에 의하면 일정 양생 지속 시간하에서 온도의 증가에 따라 콘크리트의 압축, 인장 및 휨강도가 전반적으로 증가하였다. 동일하게 일정 온도하에서 양생 지속시간이 커짐에 따라 강도들이 증가됨을 알 수 있었다. 따라서 상대적으로 높은 온도와 긴 지속 양생 조건하에서 파괴에 대한 저항력이 크게 나타났다. The compressible, tensible, and flexibleresistance of the high strength concrete is analyzed by the experimentation in the present study. For the test, we cure several samples with the silica fume as a mixture being become dense the spaces between the particle of cement under the variation of both the temperature and the curing-interval. Then, the superplasticizer and the ezcon are also used to satisfy the required workability for construction. The compressible, tensible, and flexible resistances to a stress are increased as increasing the temperature and the time interval for the curing. Therefore it is concluded that the overal fractural and mechanical properties is improved by mixing the silica fume into the cement.
만성 B형 간염환자에서 인터페론 치료 후 간 조직검사 소견의 변화와 Tumor Necrosis Factor의 임상적 의의
김홍수,윤동진,김은주,정일권,박상흠,이문호,김선주 순천향의학연구소 2000 Journal of Soonchunhyang Medical Science Vol.6 No.2
Background: Interferon has been widely used in the treatment of chronic hepatitis B, but its effectiveness is debatable. The clinical indices as the loss of HBeAg, HBV DNA, and improvement of liver function are applicated to identify the effectiveness of interferon therapy, but the mechanism of hepatohistological change is not well known. We investigated the changes of histologic finding and plasma tumor necrosis factor(TNF) in the patients with chronic hepatitis B after treatment with interferon-alpha. Methods: 11 patients with chronic hepatitis B who had treated by interferon-alpha were enrolled for this study. Liver biopsy was done before and after treatment of interferon and plasma TNF was evaluated at the same time. A semiquantitative study using a histologic scoring system was applied on pre and post liver biopsy specimens and the changes of HBeAg and HBV DNA were also evaluated. Results: Among subjects, the response group, recurrence group, and non-response group based on serologic response with clearance of HbeAg were6, 3, and 2 patients, respectively. The changes of serum ALT level and HBV DNA titer on pre and post therapy decreased significantly in the response group. The change of mean plasma TNF level in the response group decreased insignificantly to 19.4 from 19.9. The histological improvements of grading and staging were shown 4 patients in the response group. Conclusions: Serologic response with clearance of HBeAg was associated with histolofical improvement. The loss of HBsAg in the serum was significant indicator of reduction in the amount of HBV core antigen and HBV surface antigen in the hepatocytes. Plasma TNF level was not associated with response of interferon-alpha therapy and histologic activity.
유압관로내의 동특성을 이용한 비정상 유량계측에 관한 연구
이홍구,윤석주,박성규,박길문 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1
This paper describes an approach for estimating the unsteady flowrate through a hydraulic pipe lines and a components in real time. Concerning the dynamic characteristics of a hydraulic pipe lines, experimental research from the view point of focusing on the unsteady flowrate through a pipe is insufficient because of the lack of adequate flowmeters. In this experiment, a new instantaneous flowrate measurement system making use of a sharp-edged cylindrical choke and LDV has been proposed and developed by the authors. The unsteady flowrate is obtained from the measurements center-line velocity of a circular pipe using LDV and the pressure difference using a sharp-edged cylindrical choke, and experiments on the frequency characteristics are carried out. The results show a good agreement between the estimated and directly measured flowrate waveforms illustrates the validity of the method proposed here.
김재홍,윤기범,박평원,김영진,전경민,김영태,김중환,곽호,구상완,송민석,유옥,지혜구,김동원,문상은,박영립,정승호,성범진,성순제,엄주용,황정열,이기홍,이주협,전태진 대한화학요법학회 1994 대한화학요법학회지 Vol.12 No.1
The prevalence of PPNG among pretreated gonorrhea cases isolated at the STD clinic of Choong-Ku Public Health Center in Seoul has been studied and reported annually since 1981. In 1991, 123 strains of N.gonorrhoeae were isolated, among which 58(47.1%) were PPNG. In 1992, 98 starains of N.gonorrhoeae were isolated, among which 51(52.0%) were PPNG. In all, 109(49.3%) strains were found to be PPNG among 221 strains isolated between 1991-1992. The prevalence of PPNG in Seoul showed increased tendency till 1989, thereafter, it has been stationary or slightly decreasing.
원자로압력용기장 용접열영향부의 미세조직 변화가 Magnetic Barkhausen Noise 거동에 미치는 영향
김주학,윤의박,문종걸,박덕근,홍준화 韓國非破壞檢査學會 1998 한국비파괴검사학회지 Vol.18 No.4
최근 자기적 특성의 변화가 재료의 미세조직적 상태에 민감하다는 보고가 있다. 재료의 미세조직은 상(phase), 결정립의 크기, 석출물 등의 다양한 인자로 구성되며, 본 연구에서는 이러한 인자들을 이용하여 재료의 특성과 Barkhausen noise(BN)의 관계를 연관시키기 위한 시도를 하였다. ASTM A 508 Gr.3 원자로압력용기강을 대상으로 용접열영향부의 미세조직적인 변화를 일곱가지 대표적인 영역으로 구분하였고, 각 영역에서의 미세조직과 기계적특성의 변화를 파악한 후, 각 조건별로 BN을 측정하였다. 통상의 보자력이나 잔류자화 같은 자기적 성질은 큰 변화가 없었지만, BN은 미세조직의 상태에 따라 현격한 변화를 보였다. 결정립과 석출물의 크기가 증가함에 따라 BN은 증가하였고, tempered martensite 보다는 tempered bainite 조직에서 높은 BN을 나타냈다. Recent study has demonstrated that some magnetic properties are sensitive to the microstructural state of material. The ASTM A 508 Gr. 3 reactor pressure vessel steel has various microstructural changes including martensitic and bainitic phases, and various sizes of grain and precipitates in the weld heat-affected zone (HAZ). To correlate the microstructural state with Barkhausen noise (BN), specimens were prepared through simulating various weld thermal cycles using a thermal simulator. The conventional magnetic properties, i.e. coercive force, remanence and maximum induction, did not change significantly. whereas the BN amplitude and energy during a magnetization cycle changed markedly with microstructural state. The BN increased with increasing grain and carbide sizes, and the tempered bainite structure showed higher BN parameter than tempered martensite.
宋周鎬,李昌岬,洪元杓,孟琦錫,任洪彬,李廷玟,李載元,李來烈,權五憲,金振淳,李文洙 충남대학교 공업교육연구소 1982 論文集 Vol.5 No.1
This paper aims at providing a concrete plan to improve technical and vocational teacher education in the College of Industrial Education of Chungnam National University. It is intended to propose a practical four-year regular and short-term course. Also, the estimated required facilities is included in this study as well as their management. The main conclusions and recommendations are summarized as follows; 1) The numbers of students enrollment should be reduced to 220 students which is the approximate number of future demand. 2) In order to offer to the students a broader education and to cope with the increase/decrease in demand of technical and vocational teacher within a specific field, the 8 department existing at the present (Department of Architecture Engineering Education, Civil Eng. Educ., Metallurgical Eng. Educ., Mechanical Eng. .Educ., Electrical Eng. Educ., Electronic Eng. Educ., Industrial Chemistry Educ. and Industrial Technology Educ.) would be combined into 5 (Department of Construction Engineering Education, Mechanical Eng. Educ., Electrical Eng. Educ., Industrial Chemistry Educ. and Industrial Technology Educ.). 3) The short-term course program is recommened to provide additional training and education to those candidates who already have experience in technical fields to meet an occasional demand. 4) It is necessary to add the Teaching Profession Section in the administrative organization of the College.