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CFD 해석을 통한 까치 둥지 형상의 환경적응성에 관한 연구
유승천(Seung Cheon Yu),권은비(Eun Bi Kwon),이상임(Sang Im Lee),최재천(Jae Chun Choe),최재붕(Jae Boong Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Surviving for 35 billion years in the earth, living things have developed their organisms to fit the wild nature. In the earlier study, Korean magpie's nests data are collected and clarified such as shape, size, length and etc. From the obtained data, the direction of axis in horizontal section of their nests is observed to match with that of the strongest wind at the nesting site. The computational fluid dynamics analysis is conducted to validate the assumption through 20 finite element model of horizontal ellipse section. Increasing the length of the longest horizontal axis of the nests by 10% reduced the flow velocity at the midpoint of nest cup by 50%. This would help magpies to preserve heat that is crucial for the growth and survival of their offspring in the nest due to optimize the wind blocking. The finite element method result explains the way of evolution for magpie's nest construction.
노즐 이종용접부 잔류응력에 미치는 동종용접의 영향 평가
유승천(Seung Cheon Yu),정재욱(Jae Uk Jeong),장윤석(Yoon Suk Chang),김영진(Young Jin Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Determination of weld-induced residual stress has been an important issue in nuclear power industry because several failures were reported in dissimilar metal weld parts due to primary water stress corrosion cracking. In this context, a couple of remarkable round robin analyses were conducted to quantify the welding simulation variables and to establish optimized numerical analysis process. The purpose of the present research is to introduce welding simulation results for a safety and relief nozzle, which has a dissimilar metal weld part as well as a similar metal weld part. First, finite element analyses are carried out to calculate residual stresses at the inside of nozzle considering only dissimilar metal welding. Subsequently, residual stresses taking into account both the dissimilar and similar metal welding are computed. The similar metal weld effect is evaluated by comparing these analysis results and technical findings derived from the evaluation are fully discussed.