• 한국신뢰성학회지:신뢰성응용연구
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• 제4권1호
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• pp.39-64
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• 2004

Taguchi's multi-characteristic experiments seek proper choice of levels of contollable factors which satisfy that all reponses of characteristics in a desirable range simultaneously. This aim can be achieved by response surface techniques that allow more flexible in modeling than traditional Taguchi's parameter design. In this article, a multi-response surface modeling and analysis techniques is proposed to deal with the multi-characteristic optimization problem in experimentation with Taguchi's controllable and noise factors.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.119-125
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• 2005

The current automotive is seeking the improvement of performance, the prevention of environmental pollution and the saving of energy resources according to miniaturization and lightweight of the components. And the variance analysis on the basis of structure analysis and DOE is applied to the lower control am. We have proposed a statistical design model to evaluate the effect of structural modification by performing the practical multi-objective optimization considering weight, stress and fatigue lift. The lower control arm is performed the fatigue analysis using the load history of real road test. The design model is determined using the optimization of acquired load history with the fatigue characteristic. The characteristic function is made use of the optimization according to fatigue characteristics to consider constrained function in the optimization of DOE. The structure optimization of a lower control arm according to fatigue characteristics is performed. And the optimized design variable is D=47 m, T=36mm, W=12 mm. In the real engineering problem of considering many objective functions, the multi-objective optimization process using the mathematical programming and the characteristic function is derived an useful design solution.

• 동력기계공학회지
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• 제14권2호
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• pp.60-64
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• 2010

This paper introduces reliability improvement and time saving in eddy current inspection by signal characteristic optimization of multi-coil eddy current array probe. In the past, Multi-coil array probe and single probe were used for the gas turbine rotor surface inspection & defect evaluation. The multi-coil array probe was used for the broad area inspection. But the signal deviations among multi-coil array probe are maximum 28% in commercial probe. This differences were considered to impedance differences among coils, so it is very difficult to evaluate exact defect size. The signal deviations among multi-coil array probe are maximum 28% in commercial probe. So, single coil inspection was used for exact defect sizing. The purpose of this study is to improve signal deviations of multi-coil array probe. The introduced new technology can improves this deviation by adjusting input voltage in each coil. At first, apply same voltage in each coil and collect signal amplitude of each coil. And calculate new input voltage based on signal amplitude of each coil. If the signal amplitude deviation is within 5% among multi-coil array probe, the signal amplitude of multi-coil array probe is reliable. The proposed technology gives 2% signal deviation among multi-coil array probe. The proposed new technology gives reliability improvement and inspection time saving in eddy current inspection.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.277-280
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• 2008

Multi layer bellows are being manufactured for commercial vehicle because of the characteristic of high durability compared with single iaγor bellows used to passenger vehicle. Finite Element Method (FEM) study and optimization about single layer bellows are actively progressed, but FEM study about multi layer bellows which have gap between layer is rarely processed. Therefore, this article presents finite element modeling of multi layer bellows for the improvement of simulation reliability. For the shape optimization of multi layer bellows, design of experiment and Taguchi method are used.

• 한국기계가공학회지
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• 제19권9호
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• pp.1-8
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• 2020

In this study, the optimal design of the multi-cavity mold layout and packing pressure for the automobile TCU connector cover is determined based on the injection molding analysis and the desirability function method for multi-characteristic optimization. The design characteristics to be optimized are the warpage and sink marks of the product, the scrap of the feed system, and the clamping force. The optimal design is determined by performing injection molding analysis and desirability analysis for design alternatives defined by a complete combination of five mold layouts and six-level packing pressure. The optimal design shows that the desirability values for individual characteristics are quite high and balanced, and the resulting values of individual characteristics are satisfactorily low.

• 품질경영학회지
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• 제41권3호
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• pp.413-421
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• 2013

Purpose: System availability and life cycle cost are often used to evaluate the system performance and is influenced by the operation and maintenance characteristic. In this paper, we propose the method to improve life cycle cost and satisfy the target availability through redundancy allocation. Methods: We consider the redundancy is available at all items in multi level system. Thus, we assume that sub-assembly, module, components can be duplicated. Simulation and genetic algorithm are employed to optimize redundancy allocation. Results: Target availability is higher, the life cycle cost is increased. In addition, the items for redundancy are selected at higher level in multi level system if target availability is higher. Conclusion: We could know that target availability affects the duplication number of items and the selection of redundancy items. For further study, we will consider new optimization algorithms to compare with the proposed GA algorithm and improve optimization performance.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1967-1974
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• 2005

The butterfly valve has been used to control a flow effectively in the industrial because of its lightweight, simple structure and the rapidity of its manipulation. However, it is difficult to have the existing structural optimization using field analysis from CFD to structure analysis when the structure is influenced by fluid. This paper is evaluated the specificity to get the flow characteristic and stability of the butterfly valve using FEM and CFD. Also, it accomplished the shape optimization design using the orthogonal arrangement and characteristic function. Research result, a few experiments showed the optimal results of three dimensional structures to be multi-objective.

• 한국해양공학회지
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• 제19권3호
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• pp.59-65
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• 2005

In today's industry, the butterfly valve has been used to control a flow effectively. However, it is difficult to have the existing structural optimization using field analysis from CFD to structure analysis when the structure is influenced by fluid. Therefore, an initial model of this study is to evaluate the stability of the valve using FEM and CFD. And, it selected variable using initial analysis results. Also, it accomplished the shape optimization design using the orthogonal arrangement and characteristic function. Research result, a few experiments showed the optimal results of there dimensional structures to be multi-objective.

• International Journal of Precision Engineering and Manufacturing
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• 제8권4호
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• pp.10-15
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• 2007

Taguchi methods have been used for a long time to improve the product quality and process performance of a manufacturing system, Few researchers have applied this methodology in laser beam cutting (LBC) of sheet metals and found the considerable improvement in cut qualities. In all experimental investigations of LBC so far, the objective was to optimize the single quality characteristic at a time. In this paper the simultaneous optimization of multiple quality characteristics such as Kerf width and material removal rate (MRR) during pulsed Nd:YAG LBC of thin sheet of magnetic material (high Silicon-steel) has been presented using Taguchi's quality loss function. The results show the considerable improvement in multiple S/N ratio as compared to initial cutting condition. Also, the comparison of results from single and multi-objective optimization have been presented and it was found that the loss in quality is always possible shifting from single quality to multiple quality optimization.

• 산업경영시스템학회지
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• 제46권4호
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• pp.199-208
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• 2023

Taguchi method is one of the most popular approaches for design optimization such that performance characteristics become robust to uncontrollable noise variables. However, most previous Taguchi method applications have addressed a single-characteristic problem. Problems with multiple characteristics are more common in practice. The multi-criteria decision making(MCDM) problem is to select the optimal one among multiple alternatives by integrating a number of criteria that may conflict with each other. Representative MCDM methods include TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution), GRA(Grey Relational Analysis), PCA(Principal Component Analysis), fuzzy logic system, and so on. Therefore, numerous approaches have been conducted to deal with the multi-characteristic design problem by combining original Taguchi method and MCDM methods. In the MCDM problem, multiple criteria generally have different measurement units, which means that there may be a large difference in the physical value of the criteria and ultimately makes it difficult to integrate the measurements for the criteria. Therefore, the normalization technique is usually utilized to convert different units of criteria into one identical unit. There are four normalization techniques commonly used in MCDM problems, including vector normalization, linear scale transformation(max-min, max, or sum). However, the normalization techniques have several shortcomings and do not adequately incorporate the practical matters. For example, if certain alternative has maximum value of data for certain criterion, this alternative is considered as the solution in original process. However, if the maximum value of data does not satisfy the required degree of fulfillment of designer or customer, the alternative may not be considered as the solution. To solve this problem, this paper employs the desirability function that has been proposed in our previous research. The desirability function uses upper limit and lower limit in normalization process. The threshold points for establishing upper or lower limits let us know what degree of fulfillment of designer or customer is. This paper proposes a new design optimization technique for multi-characteristic design problem by integrating the Taguchi method and our desirability functions. Finally, the proposed technique is able to obtain the optimal solution that is robust to multi-characteristic performances.