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현충민,이명수,조시훈,장태원,Hyun, Chung Min,Yi, Myung Su,Cho, Si Hoon,Jang, Tae Won 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.1
Due to of high intensity, lower noise and easy controllability of the heat, induction heating system became well known. Induction heating method has been suggested as substitute for the gas heat source and adopted in the automation of curved hull forming system. In this study, an investigation was accomplished to find the effects on the change of material properties when the induction heating was applied on the mild steel plate. Plates were heated using weaving method to get sufficiently heat affected zone and then cooled with water or in the air. The mechanical properties of the heated plate were evaluated. As results, the tensile test, impact test and microstructures satisfied the class rule.
고유 변형도법과 리메슁 기술을 접목한 블록의 역세팅 형상 예측기술
현충민(Chung-Min Hyun),최한석(Han-Suk Choi),박창우(Chang-Woo Park),김성훈(Sung-Hoon Kim) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.6
In order to reduce the cost of corrections and time needed for the block assembly process, the reverse setting method is applied for a back-heated block to neutralize deck deformation. The proper reverse setting shape for a back-heated block to correct deformation improved the deck flatness, but an excessive amount of reverse setting could inversely affect the flatness of the block. A prediction method was developed for the proper reverse setting shape using a back-heated block, considering the complex geometry of blocks, thickness of the deck plate, and thermal loading conditions such as welding and back-heating. The prediction method was developed by combining the re-meshing technique and inherent strain-based deformation analysis using the finite element method. Because the flatness deviation was decreased until the lower critical point and thereafter it tended to increase again, the optimum value for which the flatness was the best case was selected by repeatedly calculating the predefined reverse setting values. Based on this analysis and the study of the back-heating deformation of large assembly blocks, including the reverse setting shape, the mechanism for selecting the optimum reverse setting value was identified. The developed method was applied to the actual blocks of a ship, and it was confirmed that the flatness of the block was improved. It is concluded that the developed prediction method can be used to predict the optimum reverse setting shape value of a ship’s block, which will reduce the cost of corrections in the construction stage.
산소-프로판 가스 곡가공 공정에서 강판의 변형예측을 위한 계산식 개발
배강열,양영수,현충민,조시훈,Bae, Kang-Yul,Yang, Young-Soo,Hyun, Chung-Min,Cho, Si-Hun 대한용접접합학회 2007 대한용접·접합학회지 Vol.25 No.2
Simplified mathematical formulas are presented to predict deformations during the plate forming process when the heating parameters are given. To obtain the formulas, firstly, the thermal analysis for steel plate is performed, and the thermo-mechanical analysis is followed with actual heating conditions. The analyses have been carried out by the commercial software MARC, which is programmed based on the FEM. Secondary, the results of the mechanical analysis are synthesized with their variables for a statistical approach, which results in simplified formulas. The results of the analysis are well compared with those of experimental measurements.
유도가열을 이용한 강판성형공정에서 변형량 예측을 위한 계산식 유도
배강열,양영수,현충민,원석희,조시훈,Bae, Kang-Yul,Yang, Young-Soo,Hyun, Chung-Min,Won, Seok-Hee,Cho, Si-Hoon 대한용접접합학회 2007 대한용접·접합학회지 Vol.25 No.4
Recently, the electro-magnetic induction process has been utilizing to substitute the flame heating process in shipyard. However, few studies have been performed to exactly analyze the deformation mechanism of the heating process with mathematical model. This is mainly due to the difficulty of modeling the inductor travelling on plate during the process. In this study, heat flux distribution of the process is firstly numerically analysed with the assumption that the process has a quasi-stationary state and also with the consideration that the heat source itself highly depends on the temperature of base plate. With the heat flux, the thermal and deformation analyses are then performed with a commercial program for 34 combinations of heating parameters. The deformations obtained and heating parameters are synthesized with a statistical method to produce simplified formulas, which easily give the relation between the heating parameters and deformations. The formulas are well compared with results of experiment.
해양플랜트 Deck 변형을 줄이기 위한 Plate Girder 역세팅 설계 시스템 개발
박창우(Chang Woo Park),현충민(Chung Min Hyun),이명수(Myung Su Yi),김호구(Ho Gu Kim),도규원(Kyu Won Doh) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.10
선박과 해양플랜트 구조물은 수많은 철판의 용접 작업을 통하여 이어 붙이게 된다. 용접 및 교정작업이 가장 많이 이루어지는 공정은 조립 공정이다. 조립 공정은 소부재 조립(소조립), 중부재 조립 및 대조립으로 이루어지고 각각의 단계 마무리는 변형 교정 작업(곡직)으로 마무리된다. 특히 대조립의 경우, 변형 교정 작업은 이미 대형화된 블록 전체가 활처럼 휘어져 위로 또는 아래로 볼록해지는 형태의 추가적인 변형을 유발하게 되어 다음 공정인 선행 탑재 품질 문제를 야기하고 있다. 이러한 문제를 해결하기 위해 역변형 형상으로 블록을 세팅하여 조립할 수 있도록 하는 시스템을 개발하여 해양플랜트에 적용하고자 하였다. 역변형 형상은 기하학적인 형상으로 단순화하여 블록의 전체 변형량을 사전에 시뮬레이션한 후에 역변형 형상으로 만들기 위한 비율 값으로 미리 설정하였고 이를 시스템화하여 CAD 시스템 내에서 자동으로 구동될 수 있도록 하였다. Most large vessels and offshore plants are constructed using small blocks via welding. Further, the associated assembly processes require a considerable amount of welding. The final step of each assembly process (sub-assembly, mid-assembly, and large-assembly) is correction, which is implemented via gas torch heating. Particularly after large-assembly, the correction step helps remove local welding deformation; however, the whole block is already bent like a bow, and hence, only limited corrections can be made to this bow. Thus, additional work is required to fix global deformation. The deformation of the design shape was simulated using a software. Further, the deformation of the block was estimated using the weld bending strain collected at the actual site after the prototype was constructed. Finally, geometrical deformation using the estimated deformation is presented.