• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1621-1626
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• 2001

The structural optimization have been carried out in the continuous design space or in the discrete design space. Methods fur discrete variables such as genetic algorithms , are extremely expensive in computational cost. In this research, an iterative optimization algorithm using orthogonal arrays is developed for design in discrete space. An orthogonal array is selected on a discrete des inn space and levels are selected from candidate values. Matrix experiments with the orthogonal array are conducted. New results of matrix experiments are obtained with penalty functions leer constraints. A new design is determined from analysis of means(ANOM). An orthogonal array is defined around the new values and matrix experiments are conducted. The final optimum design is found from iterative process. The suggested algorithm has been applied to various problems such as truss and frame type structures. The results are compared with those from a genetic algorithm and discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.125-132
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• 2002

Bumpers are structural components to reduce physical damage to the front and rear ends of a passenger motor vehicle from low speed collisions. Damage assessment and the protectiveness are the commonly used designing criteria but in this study, relative displacements of the bumper are examined. To absorb the crash energy without significant damage to the bumper itself, foam material is installed between fascia and beam. However, it is not easy to predict the exact displacements generated in bumper structures through FEM because the compressive stress-strain curve of a foam material depends on strain rates that deviates significantly on each trial. Under this uncertain condition, a range of displacements is calculated and the optimum design is performed using the design of experiments. The result will be used to find the design that minimizes the weight within displacement constraints. The orthogonal array of L9 is introduced to find the optimum of the design variables that considers the thickness of inner beam, outer beam and stay, This study will suggest the design procedure of a front bumper using the uncertain stress-strain curve of a foam material.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1005-1010
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• 2004

The structural optimization has been carried out in the continuous design space or in the discrete design space. Generally, available designs are discrete in design practice. But methods for discrete variables are extremely expensive in computational cost. In order to overcome this weakness, an iterative optimization algorithm was proposed for design in the discrete space, which is called as a sequential algorithm using orthogonal arrays (SOA). We focus to verify the fact that the local solution can be obtained throughout the optimization with this algorithm. The local solution is defined in discrete design space. Then the search space, which is the set of candidate values of each design variables formed by the neighborhood of current design point, is defined. It is verified that a local solution can be founded by moving sequentially the search space. The SOA algorithm has been applied to problems such as truss type structures. Then it is confirmed that a local solution can be obtained using the SOA algorithm

• Journal of the Korea Concrete Institute
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• v.21 no.2
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• pp.179-186
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• 2009

The peculiarity pointed out for high strength concrete is the occurrence of spalling during a fire. Recently, there are many efforts such as development of all types of spalling reducing materials and other innovative materials in various fields. Need is now to examine the adequate mixing proportions of these materials. This study intended to derive experimentally and statistically mix proportions that can represent the basic quality requirements as well as the optimal effects on the fire-resistance for 4 types of functional materials that are metakaolin, waste tire chip, polypropylene fiber and steel fiber. Here, the tests were planned through an optimal test method using an orthogonal array table with 4 parameters and 3 levels. The statistical analysis adopted the response surface analysis method. Results verified mutual complementary contribution between the materials when using a combination of the functional materials selected as parameters for the strengthening of the fire-resistance of 80 MPa-class high strength concrete. Besides, the optimal conditions of the fire-resistance strengthening materials derived through response surface analysis were a volumetric replacement of silica fume by 80% of metakaolin, a volumetric replacement of fine aggregates by 3% of tire waste chip, and an addition of 0.2% of the whole volume by polypropylene fiber without mixing of steel fiber. In such cases, the basic characteristics as well as the fire-resistant characteristics of high strength concrete were also satisfied.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.7
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• pp.627-633
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• 2009

Composite has become one of the most frequently used material for a tube of satellite camera due to its attractive characteristics. However, laminated composites can be weakened by delamination which comes from interlaminar stress. Such failure mode cause structural instability of the camera as well as degradation of optical quality. Therefore composite tube should be robust in delamination. Also, composite tube should have high stiffness, sufficient high natural frequency and small coefficient of thermal expansion. The design procedures presented in this paper are based on design of experiments. The experiments for mechanical analysis are designed by the tables of orthogonal arrays. In order to manipulate the various mechanical properties systematically, multiple-attribute decision making(MADM) is employed. Through analysis of variance and F-test, the critical design variables which have dominant influences on mechanical performance are determined. Finally improved ply angles for composite tube are determined.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4149-4155
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• 2013

High speed machining for higher cutting speed and feedrate lead to a increase of surface quality and material removal rate. This paper presents a study of the influence of cutting conditions on the vibration characteristics obtained by machining with face milling cutter for high speed machining. In this paper, Taguchi experimental design method which is based on orthogonal array table was applied to study vibration characteristics with high speed face milling cutter. The experimental conditions used orthogonal array of $L_{27}(3^{13})$. In this work, design and analysis of experiments is conducted to study the effects of these parameters on the vibration by using the S/N ratio, analysis of variance. Four cutting parameters namely, feed rate, champer length, cutting speed, and depth of cut were optimized with consideration of vibration characteristics.

• Korean Management Science Review
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• v.7 no.2
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• pp.3-21
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• 1990

제품 및 공정의 설계와 개선을 위한 다구찌 방법은 제품의 품질향상을 위한 획기적 방법으로 최근 많은 관심의 대상이 되고 있다. 본 논문에서는 품질문제 해결을 위한 다구찌의 기본 전략을 종래의 전통적 개념과의 비교를 통해 소개하였으며, 구체적 방법으로서 직교배열에 의한 실험계획과 SN비를 바탕으로 한 파라미터 설계방법에 대해 다구찌의 견해와 다른 대안들을 함께 소개하고 앞으로의 연구방향에 대해 논의하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.339-348
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• 2001

More often a commercial package for the structural analysis is necessary in the structural optimum design. In this case the task of combining the package with an optimization program must be required, hut it is not so simple because interchanging some data between them is difficult. Sequential approximate optimization is currently used as a natural way to overcome the hard task. If sequential approximate optimization has wide side constraints that the lower limit of design variables is very small and their upper limit is very large, it is not so easy to obtain approximated functions accurately for the whole design domain. This paper proposes a sequential design domain method, which is very useful to carry out sequential approximate optimization in this case. In this paper, the response surface methodology is used to obtain approximated functions and the orthogonal array is used for design of experiments. The sequential approximate optimization of 3-bar and 10-bar trusses is demonstrated to verify the reliability of the sequential design domain method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5955-5962
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• 2014

Generally, the frame design of a vehicle is a critical technology that plays an important role in the racing and high performance sports car market. The high performance of race car frame means that it requires high torsional stiffness because it directly affects the cornering behavior of the race car. The optimal design for the frame of a low-cost single seat race car was carried out using the DOE (Design Of Experiments) with Taguchi's orthogonal array and FEM (Finite Element Method) analysis to secure sufficient torsional stiffness in this paper. According to the results by DOE and FEM analysis, the optimal design case produced improved 10.7% and 14.5% improvement in each stiffness-to-weight ratio and frame weight than in the early design step. Therefore, this paper shows that the optimal design with Taguchi's orthogonal array is very useful and effective for designing a tubular space frame of a low-cost single seat race car in the early design step.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.207-212
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• 2011

A hydraulic breaker is an attachment installed at the end of excavator arm and is used for breaking. As per the authors' knowledge, there have been no research results on reducing the weight of the hydraulic breaker even though this weight reduction is very important for improving the performance of the excavator. In this study, we minimize the weight of the housing of the hydraulic breaker under normal operating conditions, while the maximum stress of the housing is lower than the allowable stress. A meta-model, which is generated by using the CAE results for the sampling design points determined by an orthogonal array, is used to solve the minimization problem. The weight of the housing according to the optimal design is found to be lower than the original weight by 4.8% while satisfying the constraint on the maximum stress.