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보수용접 모사 방법에 따른 원자로 배관 이종금속 맞대기 용접부 응력 분포
이휘승(Hwee-Seung Lee),허남수(Nam-Su Huh),김진수(Jin-Su Kim),이진호(Jin-Ho Lee) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.5
이종금속용접부에 대한 실제 용접 공정 중 용접부에서 결함이 발견되면 이를 제거하고 보수용접이 수행된다. 일반적으로 보수용접을 수행하면 용접부에서 인장 잔류응력이 크게 증가될 수 있는 것으로 알려져 있다. 따라서 Alloy 82/182를 사용하여 보수용접이 수행된 이종금속용접부의 일차수 응력부식균열 현상을 평가하기 위해서는 보수용접에 의한 용접부의 응력 변화를 정확하게 평가해야 한다. 본 논문에서는 비선형 유한요소해석을 수행하여 보수용접에 의한 원자력 이종금속 맞대기 용접부의 응력 분포를 평가하였다. 특히 보수용접 공정 모사를 위한 여러 유한요소 해석방법이 이종금속용접부의 응력분포에 미치는 영향을 평가하였다. During welding, the dissimilar metal butt welds of nuclear piping are typically subjected to repair welding in order to eliminate defects that are found during post-weld inspection. It has been found that the repair weld can significantly increase the tensile residual stress in the weldment, and therefore, accurate estimation of the weld residual stress due to repair weld, especially for dissimilar metal welds using Ni-based alloy 82/182 in nuclear components, is of great importance in order to assess susceptibility to primary water stress corrosion cracking. In the present study, the stress distributions of dissimilar metal butt welds in nuclear reactor piping subjected to repair weld were investigated based on detailed nonlinear finite element analyses. Particular emphasis was placed on the variation of the stress distribution in the dissimilar metal butt weld according to the finite element welding analysis sequence for the repair welding process.
수압시험 및 정상운전 하중을 고려한 원자로 배관 이종금속 맞대기 용접부 응력부식균열 성장 해석
이휘승(Hwee-Sueng Lee),허남수(Nam-Su Huh),이승건(Seung-Gun Lee),박흥배(Heung-Bae Park),이성호(Sung-Ho Lee) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.1
본 논문에서는 Alloy 82/182를 용접재로 이용한 원자로 배관 이종금속 맞대기 용접부(Dissimilar Metal Butt Weld)에서의 PWSCC에 의한 균열성장 거동을 평가하였다. 이를 위해 먼저 유한요소 응력해석을 수행하여 이종금속용접부에서의 응력분포를 결정하였으며, 이때 이종금속용접 및 동종금속용접에 의한 용접잔류응력 외에 수압시험과 정상운전 조건도 고려하여 기계적 하중에 의한 응력 재분배를 고려하였다. 최종적으로 이와 같이 구한 응력 분포를 바탕으로 PWSCC에 의한 축방향 및 원주방향 가상 균열의 균열성장 거동을 평가하여 PWSCC 균열 성장량을 계산하였다. 본 논문의 결과는 향후 PWSCC에 의한 원자로 배관 이종금속 맞대기 용접부의 균열성장 거동 예측에 적용될 수 있다. This study investigates the crack growth behavior due to primary water stress corrosion cracking (PWSCC) in the dissimilar metal butt weld of a reactor piping using Alloy 82/182. First, detailed finite element stress analyses were performed to predict the stress distribution of the dissimilar metal butt weld in which the hydrostatic and the normal operating loads as well as the weld residual stresses were considered to evaluate the stress redistribution due to mechanical loadings. Based on the stress distributions along the wall thickness of the dissimilar metal butt weld, the crack growth behavior of the postulated axial and circumferential cracks were predicted, from which the crack growth diagram due to PWSCC was proposed. The present results can be applied to predict the crack growth rate in the dissimilar metal butt weld of reactor piping due to PWSCC.
바람에 대한 대형 Offset 안테나의 진동 응답 분석
김상현(Sang-Hyun Kim),김병준(Byung-Jun Kim),이증(Jeung Lee),강동석(Dong-Suk Kang),이휘승(Hwee-Seung Lee) 한국소음진동공학회 2017 한국소음진동공학회 논문집 Vol.27 No.3
An antenna for satellite communication ground terminals exists in many different forms. A mobile antenna for large-volume / high-speed transmission is mostly using of offset antenna among the many antenna. This surface mounted antenna is taken the wind requirements and shall be designed by the level. This paper identifies problems of real artificial wind test by frequency response characteristics after conducting random vibration analysis using wind spectrum. Through these results, this paper also desires to draw a improvement direction that antenna can meet the requirements as developing similar large offset antenna applied the wind requirements of high level.
김상현(Sang-Hyun Kim),김미영(Mi-Young Kim),전종익(Jong-Ik Jeon),손동훈(Dong-Hun Son),이종학(Jong-Hak Lee),이휘승(Hwee-Seung Lee) 한국소음진동공학회 2019 한국소음진동공학회 논문집 Vol.29 No.1
A shelter mounted on a vehicle is equipped with an equipment rack, and a vibration-proof mount is implemented for isolation from the vehicle input vibration originating from the road surface condition. It is often different to select an appropriate vibration-proof mount at an early stage; in general, a different type of equipment rack is required for each weapons system, and various pieces of equipment are developed simultaneously during the design process. In addition, it is necessary to derive the vibration profile for the independent rack-mounting vibration-proof mount, and the vibration compatibility of commercial rack equipment. However, there is no process for the conversion of a selected vibration-proof mount to the external vibration profile presented in the Military standard. Therefore, in this study, a conversion profile is derived from a 1-degree-of-freedom vibration system and CAE vibration analysis, by separating the initial and completion stages of design. Moreover, an application method for use in the design stage of military equipment is suggested.