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이상국(Sang-Guk Lee),박종혁(Jong-Huck Park),이선기(Sun-Ki Lee),유근배(Keun-Bae Yoo),홍승열(Sung-Yull Hong) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
To verify the system performance of portable AE leak diagnosis system which can measure with moving conditions, AE activities such as RMS voltage level, AE signal trend, leak rate degree according to AE database, FFT spectrum were measured during operation on total 11 valves of the secondary system in nuclear power plant. AE activities were recorded and analyzed from various operating conditions including different temperature, type of valve, pressure difference, valve size and fluid. The results of this field study are utilized to select the type of sensors, the frequency band for filtering and thereby to improve the signal-to-noise ratio for diagnosis for diagnosis or monitoring of valves in operation. As the final result of application study above, portable type leak diagnosis system by AE was developed. The outcome of the study can be definitely applied as a means of the diagnosis or monitoring system for energy saving and prevention of accident for power plant valve.
손상원인 규명을 통한 격리밸브 스템의 구조 신뢰성 향상
하각현(Gak-Hyeon Ha),박치용(Chi-Yong Park),정용찬(Yong-Chan Jung),유근배(Keun-Bae Yoo) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
This study is concerned to the root cause analysis of isolation valve stem, which was not functioned from power plant by valve failure after short normal operation. An improvement method of structural reliability was proposed through the root cause analysis about the failed stem of gate valve type. For carrying out the root cause analysis of failed components, material characteristics of as built metal was investigated, and failed metal was analysed metallurgically for understanding the chemical components. Heat treatment effect was investigated for verifying the sound material comparing with the required specification by heat treatment test. Also, investigation of failed surface suggested that stems were failed through crack initiation in non-metallic substitution due to stress concentration and crack propagation by bending fatigue load. This study has found that a critical failure cause was verified as non-heat treatment on martensitic stainless steel. Based on critical root cause of valve stem, structural reliability of valve may be improved in the power plant field.
김형남(Hyung-Nam Kim),박치용(Chi-Yong Park),지동현(Dong-Hyun Jee),유근배(Keun-Bae Yoo) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
This study is concerned about an establishment of methodology for tube integrity evaluation due to foreign object in tube side of heat exchanger on power plants. Tube damage by foreign object in tube side treats tube integrity and makes heat exchanging function loss, nevertheless, the evaluation of tube integrity is difficult and do not established well now. The method introduced in this paper has following characteristics. a) First, some resonable conservative assumption is set up for simplifying the problems after definition of problem, b) Moving track of foreign object is followed by reviewing the geometric size of tube and foreign object, c) Establishment of integrity evaluation method based on tube damage mechanism is selected and formulated under previous assumption and d) Finally, regulatory or design requirements are checked. As an example of application for above methodology, tube integrity by two arbitrary shape foreign objects such as spring and tubing were evaluated. This method would be easily used as directional guideline for evaluating integrity of tube due to foreign object in tube side of heat exchanger on power plants.
음향방출기술을 이용한 원자력발전소 제어밸브 유체누설 상시감시에 관한 연구
이상국(Sang-Guk Lee),박종혁(Jong-Huck Park),이선기(Sun-Ki Lee),유근배(Keun-Bae Yoo),홍승열(Sung-Yull Hong) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve for high pressure turbine condensing water dump and main steam condensing water control on the normal size of 1-1/2, 2-1/2 and 2 . The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.
계층분석법을 활용한 Green City 실증단지 구축을 위한 도서 선정모형 평가
이기학(Lee, Ki-Hak),문상진(Moon, Sang-Jin),문길호(Moon, Kil-Ho),류홍우(Rhew, Hong-Woo),이태원(Lee, Tae-Won),박종포(Park, Jong-Po),최진혁(Choi, Jin-Hyeok),박태성(Park, Tae-Sung),유근배(Yoo, Keun-Bae) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
수소를 기반으로 하는 신재생에너지의 생산, 관리 및 이용 시스템을 연계하여 운전하는 Green City 실증단지 구현을 위한 국내 도서 선정은 지자체별 이해관계와 지역발전계획에 따라 첨예한 논란을 수반할 소지가 있다. 입지 선정 절차상에서 예비후보지 선정과정이 형식적이거나 입지선정기준이 없어 입지선정을 위한 평가항목, 평가기준, 항목별 배점 등이 분석자의 의도에 따라 조정될 수 있는 문제점이 있다. 또한 각 지역에 대한 입지선정을 위한 기준이 있다 하더라도 추상적이거나 객관적이지 않은 기준이 많아 입지선정에 직접 적용하기 어렵고, 자연환경, 사회경제, 법제, 입지조건, 부하특성, 지자체 호응 등 인자들의 평가의 형평성이 결여될 수 있다. 이를 해결하기 위해 의사결정도구로 이용되는 계층분석법(AHP)을 입지선정절차에 적용하였다. 객관적인 정보가 제공 가능한 평가항목을 설정하고, 관련 전문가들의 설문조사를 통하여 주관적인 중요도 결과를 취합하였다. 이 결과를 계층분석법을 활용하여 평가항목별 가치를 측정하여 가중치를 부여하였고, Green City 실증단지 구현을 위한 후보도서의 순위를 제시하였다.
류마티스성 심장판막질환, 우심방혈전 및 대동맥 협착증과 합병된 만성 혈전색전성 폐동맥고혈압 1예
유근배,심준,임양희,이진화,신길자 梨花女子大學校 醫科大學 醫科學硏究所 1998 EMJ (Ewha medical journal) Vol.21 No.4
폐동맥 혈전색전증은 비교적 드문 질환으로 주로 심부 정맥혈전에서 발생하는 것으로 알려져 있으며 류마티스성 심장판막질환을 가진 경우 합병되는 우심방 혈전이 드물게 폐혈전색전증의 원인이 될 수 있는데, 저자들은 대동맥의 동맥경화성 협착증을 동반한 류마티스성 심판막질환 환자에서 우심부전 및 우심방혈전에서 발생한 만성 혈전색전성 폐동맥고혈압1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다. Most pulmonary thromboemboli arise from the deep vein thrombosis, which have complete clinical and at least near complete roentgenographic and angiographic resolution within four to six week of the acute event. But chronic pulmonary hypertension and cor pulmonale from unresolved pulmonary embo-lism complicate acute embolic episode with a frequency of less than 1 percent. Rarely pulmo-nary thromboemboli can result from right atrial thrombi. We experienced a case of chronic thromoboembolic pulmonary hypertension, which wrose from right atrial thrombi in the patient with rheumatic valvaular heart disease and thoracic aorta atherosclerotics stenosis.