• 한국전산유체공학회지
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• 제16권2호
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• pp.56-61
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• 2011

Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is ${\beta}$-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1441-1446
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• 2003

The design optimization of the plate heat exchanger with staggered pin arrays for a fixed volume is performed numerically. The flow and thermal fields are assumed to be a streamwise-periodic flow and heat transfer with constant wall temperature and they are solved by using the finite volume method. The optimization is carried out by using the sequential linear programming (SLP) method and the weighting method is used for solving the multi-objective problem. The results show that the optimal design variables for the weighting coefficient of 0.5 are as follows; S=6.497mm, P=5.496mm, $D_1=0.689mm$, and $D_2=2.396mm$. The Pareto optimal solutions are also presented.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2033-2039
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• 1999

One of the main causes of severe wear or crack initiation in wheel and rail is the contact stress due to wheel-rail contact. In this paper, the shape design based on more reasonable contact stress analysis rather than a general Hertzian contact theory is investigated in order to reduce the contact stress. The optimal design is performed using the simple 2-D finite element model and its results are verified by 3-D finite element analysis.

• 한국생산제조학회지
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• 제24권2호
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• pp.192-197
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• 2015

In many fields, the importance of reducing weight is increasing. A product should be designed such that it is profitable, by lowering costs and exhibiting better performance than other similar products. In this study, the mass and deflection of steel structures have to be reduced as objective functions under constraint conditions. To reduce computational analysis time, central composite design(CCD) and D-Optimal are used in design of experiments(DOE). The accuracy of approximate models is evaluated using the $R^2$ value. In this study, the objective functions are multiple, so the non-dominant sorting genetic algorithm(NSGA-II), which is highly efficient, is used for such a problem. In order to verify the validity of Pareto solutions, CAE results and Pareto solutions are compared.

• Journal of Advanced Marine Engineering and Technology
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• 제11권4호
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• pp.41-49
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• 1987

Recently microcomputers have come into wide use in the field of control. They are used not only as monitors and or controllers in various plant control systems but also for Computer Aided Design of control systems. In this paper, authors propose a method to design the reduced order observers for the higher order systems and have digital simulation of time responses of the optimal state feedback control system using the maximum principle. And the real time optimal state feedback control system for the third order plant which is realized by an anolog computer is constructed by means of a microcomputer, A/D converter and D/A converter. Time responses of the real time control system are compared with those obtained by the digital simulation and their well coincedence is confirmed.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.437-442
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• 2004

The optimization of a blade sweep for a transonic axial compressor rotor (NASA rotor 37) has been performed using a response surface method and a Reynolds-averaged Wavier-Stokes (RANS) flow simulation. Two shape variables of the rotor blade, which are used to define a blade sweep, are introduced to increase an adiabatic efficiency. Data points for response evaluations have been selected by D-optimal design, and linear programming method has been used for an optimization on a response surface. The result shows that the adiabatic efficiency is increased to about 1 percent compared to that of the reference shape of the rotor blade. Relatively high increasement of the adiabatic efficiency is obtained between 20 and 60 percent span. In the present study, backward swept blade is more effective to increase the adiabatic efficiency In the axial compressor rotor.

• 대한산업공학회지
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• 제39권6호
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• pp.461-472
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• 2013

In this paper, we deal with a simulation-based reliability and maintainability design problem of a warship and want to determine the optimal values of MTBF and MTTR of all units and ALDT of the warship. The system availability and life cycle cost are used as optimization criteria and estimated by simulation. A hybrid genetic algorithm with a heuristic method is proposed to find near-optimal solutions and numerical examples are also studied to investigate the effect of model parameters to the optimal solutions and compare with a general genetic algorithm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.845-846
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• 2008

• 한국음향학회지
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• 제22권8호
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• pp.637-644
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• 2003

본 연구에서는 대표적인 수중 음향 트랜스듀서인 Tonpilz 트랜스듀서에 대하여 설계변수들이 트랜스듀서 성능에 미치는 영향을 유한요소 해석을 통하여 파악하였다. 나아가 그 결과들의 통계적 다중 회귀분석을 통하여 응력 강화 (Stress stiffening) 효과를 고려한 공진 주파수, 대역폭 및 발생 음압을 이들 설계변수들의 함수로 도출한 후, 제한 최적화법인 SQP-PD 방법을 이용해 공진 주파수 30,000 Hz 와 -3dB 대역폭 10% 이상을 가지며 최대 음압을 구현할 수 있는 트랜스듀서의 최적구조를 결정하였다. 또한 SQP-PD 방법에 의한 최적값을 유한요소 해석에 의한 값과 비교함으로써 최적값의 타당성을 검증하였고, 본 연구에서 제시한 설계법이 계산시간의 단축과 높은 정확성을 가짐을 확인하였다.

• 대한기계학회논문집A
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• 제35권9호
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• pp.1007-1013
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• 2011

상용차용 다층관 벨로우즈는 우수한 유연성과 내구성이 요구되므로 단층으로 제조되는 승용차용 벨로우즈와는 다르게 다층의 형태로 제작된다. 단층 벨로우즈의 유한요소해석과 최적화에 대한 연구는 활발히 진행되고 있으나, 층과 층사이에 갭이 존재하는 다층형 벨로우즈의 유한요소해석과 최적화 연구는 미진하다. 따라서 본 연구에서는 해석의 신뢰성 향상을 위해 다층형 벨로우즈에 적합한 유한요소 모델을 제시하였으며, 다층관 벨로우즈의 형상 최적화를 위해 실험계획법과 D-Optimal 방법에 기반을 둔 순차적 실험계획에 의한 크리깅 메타모델을 적용하였다.