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유동 시스템의 형상 최적 설계를 위한 성장-변형률법의 적용
한석영,이상환,김종필,맹주성,Han, Seog-Young,Lee, Sang-Hwan,Kim, Jong-Pill,Maeng, Joo-Sung 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.7
Shape optimization of a flow system is done to obtain the required effects, in the engineering fields. Most of these designs are accomplished by empirical or numerical analysis. In empirical analysis, it is difficult to obtain an optimal shape in the feasible design region. And, in numerical method, it usually needs much calculation expenses for shape optimization, because of design sensitivity analysis. In this study, we used the growth-strain method having only one distributed parameter such as a design variable. It optimizes a shape by making a distributed parameter such as dissipation energy uniform in a flow system, and then applied to two-flow systems. In order to overcome the stability occurred in numerical analysis performed by Azegami, the equation of volumic strain has been modified. Also, the shapes were compared with the known optimal shapes for the flow systems. Consequently, we confirm that the modified growth-strain method is very efficient and practical in shape optimization of the flow systems.
신경망 최적화 기법을 이용한 다익 홴/스크롤 시스템의 설부에 대한 형상 최적화
한석영,맹주성,유달현,진경욱,Han, Seog-Young,Maeng, Joo-Sung,Yoo, Dal-Hyun,Jin, Kyong-Uk 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.10
In order to improve efficiency of a system with three-dimensional flow characteristics, this paper presents a new method that overcomes three-dimensional effects by using two-dimensional CFD and neural network. The method was applied to shape optimization of cut-off in a multi-blade fan/scroll system. As the entrance conditions of two-dimensional CFD, the experimental values at the positions out of the inactive zone were used. The distributions of velocity and pressure obtained by two-dimensional CFD were compared with those of three-dimensional CFD and experimental results. It was found that the distributions of velocity and pressure have qualitative similarity. The results of two-dimensional CFD were used for teaming as target values of neural network. The optimal angle and radius of cut-off were determined as 71$^{\circ}$and 0.092 times the outer diameter of impeller, respectively. It is quantified in the previous report that the optimal angle and radius of cut-off are approximately 72$^{\circ}$and 0.08 times the outer diameter of impeller, respectively.
오영규,박재용,임민규,박재용,한석영,Oh, Young-Kyu,Park, Jae-Yong,Im, Min-Gyu,Park, Jae-Yong,Han, Seog-Young 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.6
The objective of this study is to integrate reliability analysis into shape optimization problem using the evolutionary structural optimization (ESO) in the application example. Reliability-based shape optimization is formulated as volume minimization problem with probabilistic stress constraint under minimization max. von Mises stress and allow stress. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., reliability index approach (RIA), performance measure approach (PMA), single-loop singlevector (SLSV) and adaptive-loop (ADL), are used. Reliability-based shape optimization design process is conducted to obtain optimal shape satisfying max. von Mises stress and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.
5-Bar 스피링을 이용한 마이크로매스퓰레이터의 변위증폭
한석영(Seog Young Han),윤상준(Sang Jun Yoon),박재용(Jae Yong Park),황준성(Jun Seong Hwang),최상혁(Sang Hyuk Choi),김민수(Min Sue Kim) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-
A micromanipulator means the device that can manipulate the object with high precision. It is required high natural frequency and sufficient workspace. To cope with this requirement, flexure hinge mechanisms have been proposed. However, previous designs are hard to satisfy the functional requirements of the system due to difficulty in modeling and optimization process applying the independent axiomatic design. Therefore, this paper suggests a new design based on semi-coupled, axiomatic design. A planar 3 DOF parallel type micromanipulator is chosen as an exemplary device. To check the effectiveness of the 5-bar spring, simulation is performed by FEM. The simulation result satisfy natural frequency and a workspace, simultaneously, which is in very close agreement with the specified goal of design.
한석영(Seog Young Han),김민수(Min Sue Kim),박재용(Jae Yong Park),황준성(Joon Sung Hwang),최상혁(Sang Hyuk Choi),이병주(Byung Ju Lee),김선정(Seon Jeong Kim) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-
A material mixing method to obtain an optimal topology for a structure in a thermal environment was suggested. This method is based on Evolutionary Structural Optimization (ESO). The proposed material mixing method extends the ESO method to a mixing several materials for a structure in the multicriteria optimization of thermal flux and thermal stress. To do this, the multiobjective optimization technique was implemented. The overall efficiency of material usage was measured in terms of the combination of thermal stress levels and heat flux densities by using a combination strategy with weighting factors. Optimal topologies having multiple thermal criteria for a printed circuit board (PCB) substrate were presented to illustrate validity of the suggested material mixing method. It was found that the suggested method works very well for the multicriteria topology optimization.
한석영(Seog-Young Han),박재용(Jae-Yong Park),김상락(Sang-Rak Kim),이원구(Won-Gu Lee),유진식(Jin-Sik Yoo),김용대(Young-Dae Kim),맹주성(Joo-Seung Maeng) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
An active micro-mixer, which was composed of an oscillating micro-stirrer in the microchannel to provide rapid, effective mixing at high flow, rates was analyzed. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight microchannel and microchannel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interactionafter the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced and stabilized. Therefore, an optimum design for a dynamic micro-mixer with an oscillating stirrer was performed using Taguchi method in order to obtain a robust solution. The design parameters were established as the frequency, the length and the angle of the stirrer and the optimal values were determined to be 2, 0.8D and ± 75°, respectively. It was found that the mixing index of the optimal design increased 80.72% compared with that of the original design.