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천진식,Cheon, Jin-Sik 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.7
An inverse method is presented to obtain material's flow properties by using small punch test. This procedure employs, as the objective function of inverse analysis, the balance of measured load-di splacement response and calculated one during deformation. In order to guarantee convergence to global minimum, simulated annealing method was adopted to optimize the current objective function. In addition, artificial neural network was used to predict the load-displacement response under given material parameters which is the most time consuming and limits applications of global optimization methods to these kinds of problems. By implementing the simulated annealing for optimization along with calculating load-displacement curve by neural network, material parameters were identified irrespective of initial values within very short time for simulated test data. We also tested the present method for error-containing experimental data and showed that the flow properties of material were well predicted.
안전정지지진 조건에서 소듐냉각고속로 핵연료 집합체의 Lifting-off 해석
이현승(Hyun-Seung Lee),윤경호(Kyung-Ho Yoon),김형규(Hyung-Kyu Kim),천진식(Jin-Sik Cheon),이찬복(Chan-Bock Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The Korea Atomic Energy Research Institute(KAERI) has been developing Sodium-cooled Fast Reactor(SFR). The stability of the fuel assembly of SFR, supported on the grid plate and held position by self weight. Top of fuel assembly has free boundary conditions. Hence, there is a concern of lifting off during SSE(Safe Shutdown Earthquake). Therefore, it is necessary to carry out the evaluation of the lifting-off of fuel assembly under vertical acceleration in consideration of the SSE.
낙하충격에 의한 소듐냉각고속로 제어봉집합체의 건전성 평가
이현승(Hyun Seung Lee),윤경호(Kyung Ho Yoon),김형규(Hyung Kyu Kim),천진식(Jin Sik Cheon),이찬복(Chan Bock Lee) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.3
소듐냉각고속로의 제어집합체는 내부덕트 및 제어봉을 갖는 제어봉집합체를 포함하고 있다. 제어봉집합체는 비상시 긴급 정지를 위하여 중력에 의하여 제어집합체 덕트내에서 낙하한다. 제어봉집합체의 낙하 시간과 충격 속도는 반응삽입시간 및 구조건전성에 관하여 중요한 변수이다. 본 연구의 목적은 낙하 충격에 의한 제어봉집합체의 동적거동 및 건전성평가를 조사하는 것이다. 제어봉집합체의 정상/비정상 낙하조건에서의 충격 해석은 상용 유한요소코드인 LS-DYNA를 사용하여 수행하였다. 낙하 충격 해석 결과, 제어봉집합체는 구조건전성을 유지하고 있으며, 비정상 조건에서도 댐퍼의 유동홀에 정상삽입 되었다. The CA (Control Assembly) of an SFR has a CRA(Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop impact. The impact analysis of the CRA under normal/abnormal drop conditions was carried out using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.
소듐냉각고속로 핵연료 집합체의 취급 및 운송시 구조건전성 평가
이현승(Hyun-Seung Lee),윤경호(Kyung-Ho Yoon),김형규(Hyung-Kyu Kim),천진식(Jin-Sik Cheon),이찬복(Chan-Bock Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The Korea Atomic Energy Research Institute(KAERI) has been developing Sodium-cooled Fast Reactor(SFR). A fuel assembly was main components of SFR. Fuel assembly must maintain structural integrity because it was contained fuel rods. One of the evaluation of structural integrity was the handling and transport conditions. A load that may occur during transport and handling of the fuel assemblies was considered. In consideration of safety, the load was applied 6 times self weight. This paper was to evaluate the structural integrity during handling and transportation of the fuel assembly.
이현승(Hyun Seung Lee),윤경호(Kyung Ho Yoon),천진식(Jin Sik Cheon),이찬복(Chan Bock Lee) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
The CA (Control Assembly) of PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor) has a CRA (Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop. In General, dynamic behavior analysis in fluids using CFD commercial code such as CFX and FLUENT. However, it is not suitable for parameter study of damping system design of control assembly because commercial code requires a lot of resource. So, KAERI developed the in-house code called HEXCON that predict dynamic behaviors (drop elevation, velocity and acceleration) of CRA. Shape of the damper and CRA was modified by considering the results of HEXCON. The impact analysis of the modified model under normal/abnormal drop conditions was performed to evaluate structural integrity using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.