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유전자 알고리즘을 이용한 구조물 손상 탐색기법에 관한 연구
우호길(Woo, Ho-Kil),최병민(Choi, Byoung-Min) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.1
In this paper, a method for identifying the location and extent of a damage in a structure using residual forces was presented. Element stiffness matrix reduction parameters in a finite element model were used to describe the damaged structure mathematically. The element stiffness matrix reduction parameters were determined by minimizing a global error derived from dynamic residual vectors, which were obtained by introducing a simulated experimental data into the eigenvalue problem. Genetic algorithm was used to get the solution set of element stiffness reduction parameters. The proposed scheme was verified using Euler-Bernoulli beam. The results were presented in the form of tables and charts.
알루미늄 2519 판재의 충격저항성 평가에 대한 수치 해석적 연구
구만회,우호길,Koo Man-Hoi,Woo Ho-Gil 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.3
In this paper, the acceptance criteria(Striking Velocities) for the A12519 weldments have been developed. Dynamic impact simulation of A12519 plate was achieved by using LS-DYNA, and predict the projectile velocity and the crack length. Also, Ballistic impact tests of A12519 plate have been performed, and compared with analysis results. Critical velocities of A12519 plate were acquired respectively, and striking velocities of A12519 weldments were calculated. Present work data will be used by basic data in ballistic impact test for A12519 weldments.
혼합날개의 주기적 유동교란에 따른 다점지지 연료봉의 고유치변화
이강희(Lee, Kang-Hee),우호길(Woo, Ho-Kil) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.3
Long and slender body, like a fuel rod, oscillating in axial flow can be unstabilized even by the small cross flow which can be activated by the flow mixer or turbulent generator. It is important to include these effects of flow disturbance in dynamic stability analysis of nuclear fuel rod. This work shows how eigen frequency of a multi-span fuel rod can be changed by the swirl flow, which is discretely generated by a flow mixer. By solving a state-space form of the eigenvalue equation for a multi-span fuel rod system, the critical velocity at which a fuel rod becomes unstable was calculated. Based on the simulation results, we evaluated how stability of a multi-spanned nuclear fuel rod with mixing vanes can be affected by the coolant flow in an operating reactor core.
구만회,이창현,김학인,우호길,Koo Man-Hoi,Lee Chang-Hyun,Gimm Hak-In,Woo Ho-Gil 한국군사과학기술학회 2005 한국군사과학기술학회지 Vol.8 No.1
In order to evaluate the credibility of the welded joint design for combat vehicle using A12519, the numerical analysis for the joint model has been studied and the results are compared with the experimental works by the impact projectiles. The numerical approach using LS-DYNA involves the process of the crack initiation and propagation as well as the applications of the failure criteria for both the ductile and brittle failures. The good agreement between the numerical and experimental works are proved.
이산 요소법을 이용한 골재 입자의 혼합 및 배출 시 골재 거동 및 강판 마모에 관한 연구
유승훈(Seung-Hun Ryu),우호길(Ho-Kil Woo) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.12
Ready-mixed concrete is unconsolidated concrete typically transported to construction sites by using mixer trucks. A proper rotation of concrete is necessary to prevent its solidification in mixer trucks during transport: in accordance with the manufacturing method and quality inspection prescribed in KSF4009, this movement is maintained after the manufacturing of concrete in professional production plants and the addition of water, solid materials, and admixtures. Unfortunately, mixer truck parts wear out over long periods of time. In order to improve the wear resistance of the main part of mixer trucks, we used a steel plate with good wear resistance or partially added a reinforcement plate. In this study, we first tested the properties of concrete (as required for the DEM), and then carried out mixing and discharge simulations to define the actual operating conditions of mixer trucks. For each condition, we calculated the amount and location of wear. The reliability of our results was finally verified by comparing them with the measurement values. Overall, this study provided basic data for an optimal design of mixer trucks: one that would reduce the vehicles’ weight and production costs.
구조 동특성 파라미터를 이용한 구조물 손상 탐색기법 비교 연구
최병민(Choi, Byoung-Min),우호길(Woo, Ho-Kil) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.3
Detection of structural damage is an inverse problem in structural engineering. There are three main questions in the damage detection: existence, location and extent of the damage. In concept, the natural frequency and mode shapes of any structure must satisfy an eigenvalue problem. But, if a potential damage exists in a structure, an error resulting from the substitution of the refined analytical finite element model and measured modal data into the structural eigenvalue equation will occur, which is called the residual modal forces, and can be used as an indicator of potential damage in a structure. In this study, a useful damage detection method is proposed and compared with other two methods. Two degree-of-freedom system and Cantilever beam are used to demonstrate the approach. And the results of three introduced method are compared.
유전 알고리즘을 이용한 일 방향 유동성 단조품의 예비성형체 설계 연구
염성호(SungHo Yeom),이종호(JeongHo Lee),우호길(HoKil Woo) 한국생산제조학회 2006 한국생산제조시스템학회 학술발표대회 논문집 Vol.2006 No.5
The main objective of this paper is to propose the optimal design method of forging process using genetic algorithm. Design optimization of forging process was doing about one stage and multi stage. The objective function is considered the filling of die. The chosen design variables are die geometry in multi stage and initial billet shape in one stage. We performed 2D FE analysis to simulated forging process. The optimized preform and initial billet shape was obtained by genetic algorithm and FE analysis.
유전 알고리즘을 이용한 일 방향 유동성 단조품의 예비성형체 설계 연구
염성호(SungHo Yeom),이종호(JeongHo Lee),우호길(HoKil Woo) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-
The main objective of this paper is to propose the optimal design method of forging process using genetic algorithm. Design optimization of forging process was doing about one stage and multi stage. The objective function is considered the filling of die. The chosen design variables are die geometry in multi stage and initial billet shape in one stage. We performed 2D FE analysis to simulated forging process. The optimized preform and initial billet shape was obtained by genetic algorithm and FE analysis.