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박치용,김진원,김양석,Park, Chi-Yong,Kim, Jin-Weon,Kim, Yang-Seok 한국유체기계학회 2000 한국유체기계학회 논문집 Vol.3 No.4
This paper provides integrity evaluation and root cause analysis for defects observed at volute tongue, or cutwater, of the operating centrifugal pump in power plant. The cause of the cracks are analyzed and reviewed from the viewpoint of the operation and maintenance of the pumps, and the sample obtained from the cracked volute tongue of the pump are examined. At first, in-situ hardness test and microstructure examination were performed to understand the cause of cracking at volute tongue. The evaluation of structural integrity and the possibility of the crack propagation is also evaluated. Cracks were typical intergranular cracking and propagated along with prior austenite grain boundary. At easing volute tongue, the hardness was higher than ASTM requirement and a large amount of intergranular Cr carbide was precipitated. These were due to high C content in material. P content was also higher than ASTM requirement. Therefore, Cr carbide precipitation and P segregation at grain boundary, caused by higher C and P content in material, resulted in intergranular cracking of casing volute tongue. This procedure for integrity evaluation and root cause analysis is used to guide, and support the pump designer and manufacturer's material selection and process design to avoid a costly, unplanned outage of plant.
볼트 체결길이 미흡에 따른 배관 플랜지의 구조 신뢰성 평가
박치용(Chi-Yong Park),신인환(In-Whan Shin),김만원(Maan-Won Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The flange connecting method is widely used in the industrial field because of using the advantages of simple installation and maintenance. The connection between flanges is fixed with bolts. If the length of the bolts in the connection part is not sufficient, a bolt has to be replaced with a new bolt. When the pipe is operating in fluid system, it may be necessary to evaluate the soundness of the flange connection for the insufficient bolt length. And then, based on the evaluation results, a faulted bolt has to be selected one of them such as immediate replacement, replacement after one cycle or continue to use. In this paper, the structural reliability for pipe flange fastening was evaluated when the bolt fastening length was in sufficient. The structural reliability was checked whether the maximum applied stress on the bolt thread surface was within the allowable stress range of the ASME code.
박치용(Chi-yong Park),김대웅(Dae-woong Kim),김양석(Yang-seok Kim),김형균(Hyoung-kyun Kim),이병오(Byoung-oh Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
On-line monitoring system is utilized for improving the plant operation reliability in the plant fleet such as fossil power plants, aircraft industry and nuclear power plants. A development project of online monitoring system has been recently carried out for updating component and system’s reliability in domestic nuclear power plant. In this paper, the development status of a centralized online monitoring system, its named CMD(Centralized Monitoring and Diagnosis) center, was introduced shortly. Lesson learned from development and application process also was shown. We would like to communicate with researchers and engineers concerning to online monitoring studies through the lessons learned from our development and application study. The stakeholder in online monitoring research would go forward to the advanced engineering goal when all parts may communicate with each others based on the appropriate role of industrial-educational relationship, the mutual comprehension of application barrier and the co-ownership for technical basis. Through all members such as researchers, application engineers and operator for online monitoring system have to get mutual comprehension and active communication, the developed and applied techniques of online monitoring would be improved and advanced to the high level with reliability of components and systems in nuclear power plants.
감육 저항 및 비저항성 재료 용접부에서 가속 두께감소 분석
박치용(Chi-Yong Park),이성호(Sung-Ho Lee),김태룡(Tae-Ryong KIM),류인근(In-Kun Ryu),이상열(Sang-Ryoul LEE) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
In has been observed that there seems to be accelerated corrosion of carbon steel immediately downstream of flow-accelerated corrosion(FAC) resistant materials. This type of damage has been observed at a number of nuclear power plant. An enhanced corrosion rate is experienced at the transition from the resistant to the non-resistant. This phenomenon is analogous to the entrance effect that occurs in heat transfer. This paper will demonstrate and testify the entrance-like effect by mass transfer and flow analysis. Various parameters such as flow velocity, corrosion track of downstream region and weld crown has been investigated by the coupled analysis of mass transfer and flow. The entrance-like effect has been observed at the bimetal weld region between resistant and non0resistant material. The enhancement of FAC rate has been also investigated. It was addressed that enhanced thickness reduction may be considered to management and inspection of thinned pipe.
내부에서 벽두께 감소된 배관의 공학적 건전성 평가 프로그램
박치용(Chi-yong Park),이성호(Sung-ho Lee),김태룡(Tae-Ryong Kim),박상규(Sang-kyu Park) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Integrity evaluation of pipes with local wall thinning by erosion and corrosion is increasingly important in maintenance of wall thinned carbon steel pipes in nuclear power plants. Though a few program for integrity assessment of wall thinned pipes have been developed in domestic nuclear field, however those are limited to straight pipes and methodology proposed in ASME Sec.XI Code Case N-597. Recently, the engineering program for integrity evaluation of pipes with all kinds of local wall defects such as straight, elbow, reducer and branch pipes was developed successfully. The program was designated as PiTEP (Pipe Thinning Evaluation Program), which name was registrated as a trademark in the Korea Intellectual Property Office. A developed program is carried out by sequential step of four integrity evaluation methodologies, which are composed of construction code, code case N-597, its engineering method and two developed owner evaluation method. As PiTEP program will be performed through GUI(graphic user interface) with user's familiarity, it would be conveniently used by plant engineers with only measured thickness data, basic operation conditions and pipe data.
지역별 장애인의 치과의료기관 공간 접근성 분석: 대도시, 중소도시, 농촌지역을 중심으로
박치용 ( Chi-yong Park ) 서울대학교 지리교육과 2014 地理敎育論集 Vol.58 No.-
본 연구의 목적은 장애인과 비장애인의 지역별 치과의료기관 공간 접근성을 비교해 장애여부와 지역특성이 치과의료기관 접근성에 어떠한 영향을 미치는지 알아보는 데 있다. 사례지역인 광주광역시, 전라남도 여수시, 전라남도 완도군은 각각 대도시, 중소도시, 농촌지역의 전형적인 특성을 지닌다. 이에 세 지역 장애인과 비장애인의 치과의료기관 공간 접근성을 2SFCA(2-Step Floating Catchment Area)에 따라 ArcGIS 9.3을 이용해 산출했다. 그 결과 세 지역 각각의 장애인과 비장애인의 치과의료기관 접근성과 접근성 상·하위 지역을 찾아 비교할수 있었다. 이러한 결과는 장애인과 농촌지역의 치과의료기관 접근성 향상이 필요하다는 것을 시사했다. The purpose of this study is to find out whether the two factors of regional characteristics and the people’s disability affect spatial accessibility to the dental institutions. The chosen example areas are Gwangju, Yeosu, and Wando, each of which has typical characteristics of metropolis, small and medium-sized city, and rural area. In this study, we calculated the able and the disabled’s spatial accessibility to the dental institutions of these three areas, using ArcGIS 9.3, following 2SFCA(2-Step Floating Catchment Area). As a result, I produce the calculation result of the able and the disabled’s spatial accessibility to the dental institutions of the example areas. I also extract the areas of the top and the bottom rank, and compare those two from the calculation result. This study suggests that it is necessary to improve spatial accessibility to the dental institutions for the disabled, and people in the rural area.