• Communications for Statistical Applications and Methods
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• 제16권1호
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• pp.195-208
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• 2009

A conventional single design optimality criterion has been used to select an efficient experimental design. But, since an experimental design is constructed with respect to an optimality criterion pre specified by investigators, an experimental design obtained from one optimality criterion which is superior to other designs may perform poorly when the design is evaluated by another optimality criterion. In other words, none of these is entirely satisfactory and even there is no guarantee that a design which is constructed from using a certain design optimality criterion is also optimal to the other design optimality criteria. Thus, it is necessary to develop certain special types of experimental designs that satisfy multiple design optimality criteria simultaneously because these multi-optimal designs (MODs) reflect the needs of the experimenters more adequately. In this article, we present a heuristic approach to construct second-order response surface designs which are more flexible and potentially very useful than the designs generated from a single design optimality criterion in many real experimental situations when several competing design optimality criteria are of interest. In this paper, over cuboidal design region for $3\;{\leq}\;k\;{\leq}\;5$ variables, we construct multi-optimal designs (MODs) that might moderately satisfy two famous alphabetic design optimality criteria, G- and IV-optimality criteria using a GA which considers a certain amount of randomness. The minimum, average and maximum scaled prediction variances for the generated response surface designs are provided. Based on the average and maximum scaled prediction variances for k = 3, 4 and 5 design variables, the MODs from a genetic algorithm (GA) have better statistical property than does the theoretically optimal designs and the MODs are more flexible and useful than single-criterion optimal designs.

• 대한기계학회논문집A
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• 제27권7호
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• pp.1210-1216
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• 2003

Topology optimization is applied to determine the layout of a structural component with a specified frequency by minimizing the difference between the specified structural frequency and a given frequency. The homogenization design method is employed and the topology design problem is solved by the optimality criteria method. The value of a weighting factor in the optimality criteria plays an important role in this topology design problem. The modified optimality criteria method approximated by using the binomial expansion is suggested to determine the suitable value of the weighting factor, which makes convergence stable. If a given frequency is set as an excited frequency, it is possible to avoid resonance by moving away the specified structural frequency from the given frequency. The results of several test problems are compared with previous works and show the validity of the proposed algorithm.

• 대한토목학회논문집
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• 제7권1호
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• pp.23-31
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• 1987

본(本) 연구(硏究)는 처짐과 응력제약(應力制約)을 받는 평면(平面)뼈대의 정확(正確)한 최적설계(最適設計)를 얻을 수 있는 Optimality Criteria 방법(方法)을 제시(提示)하고 있다. 여기서 평면(平面) 뼈대의 맨 윗층의 횡변위(橫變位)만을 거동적(擧動的) 제약(制約)에 포함(包含)시킴으로써 수학적(數學的)으로 엄격(嚴格)하면서도 효율적(効率的)인 방법(方法)이 되도록 하였다. 부재(部材)의 휨응력(應力)은 fully-stressed-design의 개념(槪念)에 근거(根據)하여 부차적(副次的) 제약(制約)으로만 취급(取扱)되었으나 최종설계(最終設計)의 최적성(最適性)을 判별(判別)하기 위하여 최종(最終) 단계(段階)에서 이들을 모두 거동적(擧動的) 제약(制約)으로 취급(取扱)한 새로운 Optimality Criteria를 유도(誘導)하고 이의 만족(滿足) 여부(與否)를 알아 보도록 하였다. 이 방법(方法)은 단순(單純)하고 효율적(効率的)이면서도 엄격(嚴格)한 Optimality Criteria를 채용(採用) 함으로써 보다 나은 설계(設計)를 구(求)할 수 있음을 예제(例題)를 통(通)하여 보였다.

• 품질경영학회지
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• 제32권3호
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• pp.234-243
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• 2004

In this paper, we study the optimality of 2-level resolution V minimal fractional factorial designs which can be constructed by using a partially balanced array. Moreover the relative efficiencies of such designs are compared in the sense of three optimality criteria such as determinant(D)-optimality, trace(A)-optimality, and eigenvalue(E) -optimality criterion.

• 한국지능시스템학회논문지
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• 제12권1호
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• pp.44-51
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• 2002

본 연구는 선형 생성을 위하여 목적함수로서 fairness 기준을 도입하고 설계변수를 B-spline 곡선의 조정점으로 하며 설계자에 의해서 주어지는 기하학적 제약조건을 만족하도록 하는 최적화를 수행하도록 하였다 본 연구에서는 최적화 방법으로서 GA(Genetic Algorithm)와 최적성 기준(optimality criteria)을 병행하였다.

• 대한조선학회논문집
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• 제39권4호
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• pp.60-65
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• 2002

본 연구는 Form Parameter를 만족하는 선형 생성 과정을 최적화 과정으로 취급하였다. 목적함수는 fairness 기준을 도입하고 설계변수는 B-spline 곡선의 조정점으로 하며 제약조건은 설계자에 의해서 주어지는 기하학적 형상으로 하였다. 최적화 방법은 GA(Genetic Algorithm)와 최적성 기준(optimality criteria)을 병행하였다.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2005년도 학술발표대회 논문집
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• pp.109-113
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• 2005

Optimality for block designs have received much attention in the literature. Here we review these criteria and present results showing their A,D and E connection. Also we acquainted with the mathematical methods of designing optimal experiments. In this paper, we will to do work about optimality in experimental designs.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권2호
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• pp.129-135
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• 2017

Purpose: This article provides step-stress accelerated degradation test (ADT) plans based on the Wiener process. Method: Step-stress levels and the stress change times are determined based on the D-optimality criteria to develop test plans. Further, a simple grid search method is provided for obtaining the optimal test plan. Results: Based on the solution procedure, ADT plans which include the stress levels and change times are developed for conducting the reliability test. Conclusion: Optimal step-stress ADT plans are provided for the case where the number of measurements is small.

• 한국정밀공학회지
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• 제19권11호
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• pp.137-145
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• 2002

Electric vehicle body has to be subjected to uniform load and requires auxiliary equipment such as air pipe and electric wire pipe. Especially, the cross beam supports the weight of passenger and electrical equipments. a lightweight vehicle body is salutary to save operating costs and fuel consumption. Therefore this study is to perform the size and the shape optimization of crossbeam for electric vehicle using the method of topology optimization to introduce the concept of homogenization based on optimality criteria method which is efficient for the problem having the number of design variables and a few boundary condition. this provides the method to determine the optimum position and shape of circular hole in the cross beam and then can achieve the optimal design to reduce weight.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.224-232
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• 1999

Topology optimization has evolved into a very efficient concept design tool and has been incorporated into design engineering processes in many industrial sectors. In recent years, topology optimization has become the focus of structural design community and has been researched and applied widely both in academia and industry. There are mainly tow approaches for topology optimization of continuum structures ; homogenization and density methods. The homogenization method is to compute is to compute an optimal distribution of microstructures in a given design domain. The sizes of the micro-calvities are treated as design variables for the topology optimization problem. the density method is to compute an optimal distribution of an isotropic material, where the material densities are treated as design variables. In this paper, the density method is used to formulate the topology optimization problem. This optimization problem is solved by using an optimality criteria method. Several example problems are solved to show the usefulness of the present approach.