• 대한기계학회논문집A
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• 제34권9호
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• pp.1305-1310
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• 2010

복잡한 시스템 계의 설계정보를 효과적으로 추출하기 위해서 형상최적설계가 수행되는 경우, 일반적으로 유한요소해석 기법과 D-최적배열을 이용한 실험계획법이 연동된 반응표면모델을 구성하고 여기에 최적설계기법이 적용된다. 그러나, 설계변수에 형상공차와 같은 변동성이 존재하면 최적해의 강건성 확보를 위하여 설계변수의 형상공차를 확률론적인 변동성으로 고려한 추가적인 강건설계가 필요하다. 본 연구에서는 계산시간이 많이 소요되는 유한요소해석에 의한 강건설계문제에 설계변수의 표준정규분포를 고려한 반응표면모델을 구축하여 최적설계를 수행하므로서 손쉽게 강건최적값을 구하는 방법을 제안하였다. 승용차용 브레이크 디스크에 제안된 방법을 적용하여 열변형과 중량을 최소화하는 설계변수의 강건최적해를 구하고, 몬테카를로 시뮬레이션 추정결과와 비교하여 이의 적합성을 검증하였다.

• 대한기계학회논문집A
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• 제24권1호
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• pp.215-224
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• 2000

In order to reduce the variation effects of uncertainties in the engineering environments, new robust optimization method, which considers the uncertainties in design process, is proposed. Both design variables and system parameters are considered as random variables about their nominal values. To ensure the robustness of performance function, a new objective is set to minimize the variance of that function. Constraint variations are handled by introducing probability constraints. Probability constraints are solved by the advanced first order second moment (AFOSM) method based on the reliability theory. The proposed robust optimization method has an advantage that the second derivatives of the constraints are not required. The suggested method is examined by solving three examples and the results are compared with those for deterministic case and those available in literature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.870-875
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• 2004

Current trend of design technologies shows engineers to objectify or automate the given decision-making process. The numerical optimization is an example of such technologies. However, in numerical optimization, the uncertainties are uncontrollable to efficiently objectify or automate the process. To better manage these uncertainties, Taguchi method, reliability-based optimization and robust optimization are being used. To obtain the target performance with the maximum robustness is the main functional requirement of a mechanical system. In this research, the robust design strategy is developed based on the DACE and the global optimization approaches. The DACE modeling, known as the one of Kriging interpolation, is introduced to obtain the surrogate approximation model of the system. The robustness is determined by the DACE model to reduce the real function calculations. The simulated annealing algorithm of global optimization methods is adopted to determine the global robust design of a surrogated model. The mathematical problems and the MEMS design problem are investigated to show the validity of the proposed method.

• 한국소음진동공학회논문집
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• 제12권10호
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• pp.773-784
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• 2002

This paper proposes an optimal design to improve the performance of the intake system by reducing the noise. We adapt the Taguchi method and column merging method for the above design. At the first stage of the design, the length and radius of each component of the current intake system are selected as control factors. Then the $L^{18}$ table of orthogonal array is used to get the effective main factors. At the second stage, the $L^{16}$ table of orthogonal array and the column merging method is combined to analyze subdivided significant factors. We know that the robust design with the column merging method provides better design for noise of intake system than the robust design itself.

• 대한기계학회논문집A
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• 제28권9호
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• pp.1368-1383
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• 2004

Robust design has been developed with the expectation that an insensitive design can be realized. That is, a product designed by robust design should be insensitive to external noises or tolerances. Robust design can be classified into three methods: (1) The Taguchi method (2) robust optimization (3) robust design by the axiomatic approach. In this paper, each method is reviewed and investigated. Pros and cons fur each method are discussed and a future direction for development is proposed.

• 대한기계학회논문집A
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• 제27권6호
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• pp.905-913
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• 2003

Generally, most of optimization have been performed with fixed sizes and variables. But, the optimum value considering tolerance of design variables and material properties, might be useless owing to exist in infeasible region. It is needed that the tolerance of design variables and material properties is considered for a real design problem. A deterministic optimal solution can be in the feasible region by performing robust optimization considering tolerance. In the paper, robust design is suggested to gain an optimum insensitive to variation of design variables and it is applied for optimization problem of caliper disc brakes for vehicles.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1763-1768
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• 2003

Current trend of design technologies shows engineers to objectify or automate the given decision-making process. The numerical optimization is an example of such technologies. However, in numerical optimization, the uncertainties are uncontrollable to efficiently objectify or automate the process. To better manage these uncertainties, Taguchi method, reliability-based optimization and robust optimization are being used. Based on the independence axiom of axiomatic design theory that illustrates the relationship between desired specifications and design parameters, the designs can be classified into three types: uncoupled, decoupled and coupled. To best approach the target performance with the maximum robustness is one of the main functional requirements of a mechanical system. Most engineering designs are pertaining to either coupled or decoupled ones, but these designs cannot currently accomplish a real robustness thus a trade-off between performance and robustness has to be made. In this research, the game theory will be applied to optimize the trade-off.

• 한국기계가공학회지
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• 제20권12호
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• pp.92-99
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• 2021

The ever-growing demand for enhanced competitiveness of engineered systems require designing in quality strategies that can efficiently incorporate multiple design attributes into a system. In a robust design, there must be consideration for any uncontrollable factors that should not be disregarded in the design process. Studies on multi-attribute design challenges usually assume mutual utility independence amongst the design attributes. However, mutual utility independence does not exist in every design situation. In this study, a new robust design methodology that has two utility-dependent attributes are presented. The proposed method was then compared with a traditional robust design that utilizes a wave soldering process design. The results of this case study indicate that the proposed method yields a better solution than the traditional method.

• 한국항공우주학회지
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• 제43권11호
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• pp.998-1007
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• 2015

방사형 인공위성 경우, 관성곱이 커서 단일 입 출력 가정이 불가능하기 때문에 고전적 제어기 설계방법을 사용하기 어렵다. 본 논문에서 현대 제어 이론인 $H_{\infty}$ 제어기 설계이론을 사용하여 방사형 인공위성의 자세 제어기 설계를 수행하였다. 설계 알고리즘으로 보다 안정적인 LMI 방법이 사용되었고, 설계 결과에 대한 안정성과 성능에 대한 강건성 해석을 위해 ${\mu}$-해석 방법이 적용되었다. 설계 결과, 일반적인 경우와 다르게 제어기가 포함되지 않은 개루프보다 제어기가 포함된 개루프의 cross-over frequency가 더 낮게 설계되는 것이 관측되었다. 즉 상대적으로 큰 관성곱 영향 때문에 단지 weighting 함수 조정으로 위성 기동성을 증가시키는데 한계가 있는 것으로 해석된다. ${\mu}$-해석을 위해 +/-5%의 관성모멘트 변화를 가정하였다. 안정성 및 성능에 대한 강건성 해석결과, +/-7% 관성모멘트 변화까지 시스템 안정성 및 성능이 보장됨이 확인되었고, 관성곱 변화보다 주관성모멘트 변화가 안정성 및 성능 저하에 더 영향을 주는 것으로 확인되었다.

• 한국정밀공학회지
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• 제9권1호
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• pp.18-28
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• 1992

시스템의 모델링 과정에서 발생될 수 있는 불확실성(uncertainty) 혹은 미지의 가반중량을 비롯한 외란에 의해 발생되는 불확실성 등을 갖고있는 로봇의 강건 추적제어기 설계를 위해 가변구조시스템(variable structure system) 이론을 적용하였다. 시스템 방정식과 연계하여 슬라이딩 모드가 존재하기 위한 조건을 구했으며, 입력 에 대한 불확실성은 매칭조건(matching condition)을 가정하여 다루었다. 기존의 방법에 비해 제어기 설계과정이 간단 명료하며 요구되는 궤적에 대한 추적제어 효과 또한 매우 우수함을 컴퓨터 시뮬레이션을 통해 입증하였다.