고유진동수를 고려한 디스크 브레이크의 최적설계

유정훈(Jeonghoon Yoo),한상훈(Sang-Hoon Hahn) 한국소음진동공학회 2003 한국소음진동공학회 학술대회논문집 Vol.2003 No.11

자기장내 구조물에 대한 위상최적화의 적용

유정훈(Jeonghoon Yoo) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.6

It is necessary to improve the performance of the current electric devices considering volumetric constraints. This study is focused on the application of the homogenization design method (HDM) into such devices to increase the magnetic flux density by changing the structural topology. This is accomplished by obtaining the optimal material distribution in a design domain to maximize the magnetic mean compliance. The HDM is used to compute the magnetic permeability connected with the design variables and the optimal material distribution is obtained according to the density of each element in the design domain. The developed method is applied to a simple C-core model and results show that the HDM is valid to achieve the design objective.

적외선 피탐지를 위한 페이즈 필드법 기반의 적외선 반사층 설계

허남준,유정훈,Heo, Namjoon,Yoo, Jeonghoon 한국전산구조공학회 2015 한국전산구조공학회논문집 Vol.28 No.1

본 연구에서는 페이즈 필드법을 기반으로 하는 위상 최적설계 방법을 통하여 적외선 스텔스 효과를 위한 적외선 반사층의 설계를 진행하였다. 이를 위하여 수직으로 입사하는 적외선 파를 반사층에서 반사되어 원하는 방향으로 전파되도록 모델링을 하였다. 전파 방향에 측정 영역을 설정하여 해당 영역에서의 목적함수 값을 최대화하도록 설계가 진행되었으며, 이때 목적함수는 전자기파의 에너지 흐름을 나타내는 포인팅 벡터(Poynting vector)로 설정하였다. 페이즈 필드법 기반의 방법에서의 여러 파라미터 값들을 변경해 가며 설계 결과를 도출하였고, 목적함수 값을 최대화하는 모델을 최적 모델로 선정하였다. 선정된 최적 모델에서 gray scale을 cut-off 방법으로 제거한 경우 더 좋은 결과를 얻을 수 있었다. 또한 중적외선 영역에서의 효과를 고려하기 위하여 입사되는 파장을 바꿔가며 얻은 해석결과를 검토하였다. 본 연구의 유한요소해석 및 최적화 과정은 상용 프로그램인 COMSOL과 Matlab을 연동하여 수행하였다. In this paper, infrared reflector design targeting infrared stealth effect is presented using structural optimization based on the phase field method. The analysis model was determined to accomplish the design that an incident infrared wave was reflected to a desired direction. The design process was to maximize the objective value at the measuring domain located in a target region and the design objective was set to the Poynting vector value which represents the energy flux. Optimization results were obtained according to the variation of some parameter values related to the phase field method. The model with a maximum objective value was selected as the final optimal model. The optimal model was modified to eliminate the gray scale using the cut-off method and it confirmed improved performance. In addition, to check the desired effect in the middle wave infrared range(MWIR), the analysis was performed by changing the input wavelength. The finite element analysis and optimization process were performed by using the commercial package COMSOL combined with the Matlab programming.

반응표면법을 이용한 솔레노이드형 자기액추에이터의 치수 최적화 설계

소현준(Hyunjun Soh),유정훈(Jeonghoon Yoo) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4

Solenoid type magnetic actuator is the device, which could translate the electromagnetic energy to<br/> mechanical force. The force generated by magnetic flux, could be calculated by Maxwell stress tensor method.<br/> Maxwell stress tensor method is influenced by the magnetic flux path. Thus, magnetic force could be<br/> improved by modification of the iron case, which is the route of the magnetic flux. Modified design is<br/> obtained by parameter optimization using by Response surface methodology.

실험 계획법을 이용한 위상최적 설계

이충용(Choong-yong Lee),유정훈(Jeonghoon Yoo),송치오 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Topology optimization methods such as density method and homogenization method need designers to consider relationships between material and density of element, relaxation of design space, etc. In this paper, we proposed a modified topology optimization method to assist designers who do not have mathematical or theoretical backgrounds of the topology optimization. Topology optimization of structures can be achieved by the design of experiment and sensitivity analysis. Grouping elements in a design variable, the design variable has 0 for existence or 1 for absence. We conducted the design of experiments with an orthogonal array and sensitivity analysis of design variables to determine sensitive variables and insensitive variables used for connectivity between elements. This modified topology optimization method has advantages such as freedom from penalizing intermediate values and preventing checker-board problems frequently occur in the topology optimization process.

페이즈 필드법을 이용한 박막형 태양전지의 광포획층 설계

허남준(Namjoon Heo),유정훈(Jeonghoon Yoo) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.9

본 연구는 페이즈 필드법 기반으로 하는 위상최적화를 이용하여 박막형 태양 전지의 광포획 구조의 반사층 설계를 목표를 하였다. 이를 위하여 입사된 빛이 설계영역인 반사층에서 반사되어 원하는 방향으로 진행하도록 하고자 하였다. 또한 같은 방법을 근적외선 영역의 반사판의 설계에 적용한 적외선 피탐지 구조의 개념 설계를 수행하였으며, 페이즈 필드법 기반의 결과와 밀도법 기반의 결과를 비교하였다. 목적함수는 에너지의 흐름을 나타내는 포인팅 벡터값의 최대화로 설정하였고, 반사된 빛의 방향을 조절하기 위하여 지정된 측정영역에서 값을 측정하였다. 본 연구의 유한요소해석 및 최적화 과정은 상용 프로그램인 COMSOL과 Matlab 프로그램을 이용하여 수행되었다. This study focused on the design of the reflecting layer of a light trapping system fora thin film solar cell using topology optimization based on the phase field method. Therefore, incident light was caused to propagate in the desired direction by reflecting it from this layer, which is the design domain. The same method was applied to the conceptual design of an infrared stealth structure in near infrared range. The results using the phase field method were compared with those using the density method. The design objective was to maximize the Poynting vector value representing the energy flux, which was measured in a measuring domain to control the reflected wave direction. A finite element analysis and optimization process were performed using the commercial package COMSOL combined with the MATLAB programming.

와전류 브레이크의 영구자석배열 최적설계

최재석(Jae Seok Choi),유정훈(Jeonghoon Yoo) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7

Eddy current is usually generated in the material with high conductivity by time-varying source such as AC current and also is induced by the moving source with relative velocity. The contactless magnetic brake makes use of the braking force from the eddy current generated by the moving source and currently used for the secondary brakes of heavy trucks, buses and rail vehicles. This study aims to design the magnetization pattern of the eddy current brake system of a permanent magnet type where the design aim is to maximize the braking force. The analysis of brake systems is based on the two-dimensional finite element analysis. We use the sequential linear programming as the optimizer and the adjoint variable method is applied for the sensitivity analysis.

실험 계획법을 이용한 위상최적 설계

이충용(Choong-yong Lee),유정훈(Jeonghoon Yoo),송치오(송치오) 한국자동차공학회 2005 한국자동차공학회 Symposium Vol.- No.-

Topology optimization methods such as density method and homogenization method need designers to consider relationships between material and density of element, relaxation of design space, etc. In this paper, we proposed a modified topology optimization method to assist designers who do not have<br/> mathematical or theoretical backgrounds of the topology optimization. Topology optimization of structures can be achieved by the design of experiment and sensitivity analysis. Grouping elements in a design variable, the design variable has 0 for existence or 1 for absence. We conducted the design of experiments with an orthogonal array and sensitivity analysis of design variables to determine sensitive variables and insensitive variables used for connectivity between elements. This modified topology optimization method has advantages such as freedom from penalizing intermediate values and preventing checker-board problems frequently occur in the topology optimization process.

현가장치 부품의 통합최적화 기법에 관한 연구

이종홍(jonghong Lee),유정훈(Jeonghoon Yoo) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Vehicle suspension systems are parts which effect performances of a vehicle such as ride quality, handling characteristics, straight performance and steering effort, etc. Moreover, through the finite element analysis by<br/> the computer, the accuracy of initial design steps becomes higher than that of the former days. In the design of a suspension system, system vibration and structural rigidity must be considered simultaneously. so far. In this paper we consider the weight reduction and the increase of the first eigen-frequency of a suspension part, especially on the upper control arm, using topology optimization and size optimization. Firstly, we obtained the initial design by using the topology optimization. And then, we applied the multi-objective optimization method to satisfy both the weight reduction and the increase of the first eigen-frequency. The design variables are fluctuating during the optimization process by the multi-objective optimization method. Therefore, we determined the robust values of the design variables not only to satisfy the terms of fluctuation limits but also to optimize the two design parameters at the same time.<br/> <br/>

복합판재의 수치-실험적 고찰 및 최적화 설계

박명수(Myungsoo Park),유정훈(Jeonghoon Yoo),정동택(Dong-Teak Chung) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.10

To predict the behavior of dual plate, 5052 aluminum and 1002 cold rolled steel, numerical and experimental approaches are attempted. For a numerical analysis, explicit finite element code, NET2D is utilized to consider nonlinear characteristics of materials under the ballistic impact. To characterize mechanical features of each plate, material properties of the Johnson-Cook constitutive model are generated by fitting the parameters from tensile test and impact test. Based on the numerical results, multi-objective optimization to minimize mass and maximize strength of dual plate is achieved. In addition, the air-gap effect is researched.