• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.700-703
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• 2004

A reliability analysis and design procedure based on the design of experiment (DOE) is combined with the response surface method (RSM) for numerical efficiency. The procedure established is based on a 3$^n$ full factorial DOE for numerical quadrature using explicit formula of optimum levels and weights derived for general distributions. The full factorial moment method (FFMM) shows good performance in terms of accuracy and ability to treat non-normally distributed random variables. But, the FFMM becomes very inefficient because the number of function evaluation required increases exponentially as the number of random variables considered increases. To enhance the efficiency, the response surface moment method (RSMM) is proposed. In RSMM, experiments only with high probability are conducted and the rest of data are complemented by a quadratic response surface approximation without mixed terms. The response surface is updated by conducting experiments one by one until the value of failure probability is converged. It is calculated using the Pearson system and the four statistical moments obtained from the experimental data. A measure for checking the relative importance of an experimental point is proposed and named as influence index. During the update of response surface, mixed terms can be added into the formulation.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.146-154
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• 2009

In recent tissue engineering field, it is being reported that the fabrication of 3D scaffolds having high porous and controlled internal/external architectures can give potential contributions in cell adhesion, proliferation and differentiation. To fabricate these scaffolds, various solid free-form fabrication technologies are being applied. The solid free-form fabrication technology has made it possible to fabricate solid free-form 3D microstructures in layer-by-layer manner. In this research, we developed a multi-head deposition system (MHDS) and used design of experiment (DOE) to fabricate 3D scaffold having an optimized internal/external shape, Through the organization of experimental approach using DOE, the fabrication process of scaffold, which is composed of blended poly-caprolactone (PCL), poly-lactic-co-glycolic acid (PLGA) and tricalcium phosphate (TCP), is established to get uniform line width, line height and porosity efficiently Moreover, the feasibility of application to the tissue engineering of MHDS is demonstrated by human bone marrow stromal cells (hBMSCs) proliferation test.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.99-107
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• 2009

Since a long work piece influences the natural frequency of the entire system with a miniature high speed spindle, a bar-feeder is used for a long work piece to improve the vibration characteristics of a spindle system. Therefore, it is very important to design optimally support positions between a bar-feeder and a long work piece for a miniature high speed spindle system. The goal of the current paper is to present an optimization method for the design of support positions between a bar-feeder and a long work piece. This optimization method is effectively composed of the method of design of experiment (DOE), the artificial neural network (ANN) and the genetic algorithm (GA). First, finite element models which include a high speed spindle, a long work piece and the support conditions of a bar-feeder were generated from the orthogonal array of the DOE method, and then the results of natural vibration analysis using FEM were provided for the learning inputs of the neural network. Finally, the design of bar-feeder support positions was optimized by the genetic algorithm method using the neural network approximations.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.66.2-66.2
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• 2010

미니탭(Minitab) 프로그램에 있는 실험계획법(Design of experiment)를 이용하여 박막실리콘 I-layer의 주효과 및 교호작용에 대한 연구를 실시하였다. I-layer의 주요 특성은 증착속도 및 전도도에 대하여 분석을 하였으며, 최종적으로 선택된 증착조건을 사용하여 비정질 실리콘 태양전지를 제조하여 확인 하였다. 실험설계는 2수준 5인자 완전설계요인법을 사용하였다. 분석결과 단막의 증착속도에 영향을 주는 주효과로는 Power와 E/S거리고 나타났으며, Power와 E/S거리, Power와 Pressure에서 큰 교호작용이 일어남을 확인 할 수 있었다. 암전도의 영향을 주는 주효과는 Sub. Temp.를 제외하고는 모두 영향을 주고 있었으며, 상당히 복잡한 교호작용을 이루고 있어 정확한 분석을 할 수는 없었다. 광전도도의 경우도 주효과에서 SiH4 flow rate를 제외하고는 모두 영향을 주고 있었으며, 복잡한 교호작용으로 정확한 분석이 어려웠다. 따라서 P-value를 분석하여 최종 R-제곱값이 증착속도는 97%이상의 높은 값을 얻었으나 전도도의 경우 최대차수 3차항으로 70~80%정도의 낮은 값을 얻었을 수 있었다. 낮은 값을 얻은 이유로는 실험설계시 몇몇 조건이 불안정한 plasma 상태로 인하여 전도도의 측정 편차가 커 분석오차가 높았을 것으로 추정된다. 암전도를 망소특성, 광전도도를 망대특성으로 광민감도 $10^5$으로 최적화 하여 비정질 태양전지를 만들어 평가한 결과 약 9%대의 광변환 효율을 얻을 수 있었으나 만족도 40%대의 낮은 값으로 향후 이와 관련한 더 정밀한 측정 및 분석이 요구된다.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.468-475
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• 2012

A proper stacking force and assembly are important to the performance of fuel cell. Improper assembly pressure may lead to leakage of fuels and high interfacial contact resistance, excessive assembly pressure may result in damage to the gas diffusion layer and other components. The pressure distribution of gas diffusion layer is important to make interfacial contact resistance less for stack performance. To analyze the influence of design parameter factors for pressure distribution, and to optimize stack design, DOE (Design of Experiment) was used for polymer electrolyte membrane fuel cell stack pressure test. As commonly known, the higher clamping force improves the fuel cell stack performance. However, non-uniformity of stress distribution is also increased. It shows that optimization between clamping force and stress distribution is needed for well designed structure of fuel cell stack. In this study, stack design optimization method is suggested by using FEM (Finite Element Methode) and DOE for light-weighted fuel cell stack.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7377-7384
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• 2015

Agricultural tractors must have a function of ROPS to protect drivers under roll-over accident. In this study, finite element analyses and an optimal design were performed to reduce the cost and the production period of the cabin frame of a tractor to pass the ROPS strength test. To confirm the pass of ROPS strength test of an initial design model, the results of deformation and principal strain from the analyses were evaluated. To reduce the weight of the cabin frame, design of experiment of Taguchi was implemented, and an optimal design was obtained. The weight of the optimal design model was reduced by 7% comparing with the initial design model.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.92-98
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• 2010

The design of press bonding tool in LCD module equipment is a very complex and difficult task because many design able variables are involved while their effects are not known. It takes longtime experiments and much expenses to verify the effects of these design variables. However the optimization of bonding tool using OLB(outer lead bonding) and PCB Bonding is a very important problem in LCD manufacturing process, so much design efforts have been made for improving the bonding tool performance. In this paper, a reasonable and fast process which gives optimized solution under the design requirements has been presented. Both analytical and statistical methods are employed in this process. A reliable analytic model using experiment-oriented FE analysis can be obtained, in which the regression equations that predict the tool efficiency from various DOE method are found. Improvement of tool efficiency could be estimated by the regression equations using meaningful factors converged by RSM(Response Surface Method). With this process a reasonable optimized solution that meets a variety of design requirements can be easily obtained.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.3
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• pp.184-192
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• 2014

The resistance of a high speed monohull can be dramatically increased at the high speed range due to the severe stern trim, spray formation and hull bottom pressure irregularity etc. In order to avoid these demerits associated with this resistance increase, various appendages such as the stern wedge, vertical wedge, stern flap, spray strip etc. have been studied. Each of appendage can control the trim angle and/or improve the resistance performance. If these appendages are combined for finding the maximal resistance reduction, there are enormous combination selections. This paper presents the DOE(Design of experiment) using an orthogonal array in order to decrease the model tests finding the optimum appendage combination. And we evaluate that the method introduced in this paper makes the optimal combination of appendages efficient and time-saving by applying to high speed semi-planing monohull. Here, the maximum speed and the least fuel expense are adopted as the decision criteria.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.93-100
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• 2013

This paper propose a method to design the rotor of synchronous reluctance motors(SynRM) for maximum torque and power factor by using DOE(design of experiment) with the design variables which are parameters of barriers and segments. In this process, there are problems that require lots of simulation time and number of simulations when calculating the both torque and power factor using the finite element method in order to find load angle, core loss per speed. In order to improve this problem, we calculate only value of flux linkage by finite element method, and can decrease analysis and the number of analysis time by applying steady state expression of the power factor and torque. Finally, in order to verify the characteristics of optimal model, we make prototype motor and compare with the conventional SynRM. In this experiment, we use the DC current decay test for calculating d-and q-axis inductance.

• Transactions of Materials Processing
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• v.9 no.5
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• pp.512-525
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• 2000

Designers are frequently faced with multiple quality issues in injection molded parts. These issues are usually In conflict with each other, and thus tradeoff needs to be made to reach a final compromised solutions. The objective of this study is to develop an automated injection molding design methodology, whereby part defects such as warpage and weld line are optimized. The features of the proposed methodology are as follows: first, Utility Function approach is applied to transform the original multiple objective problem into single objective problem. Second is an implementation of a direct search-based Injection molding optimization procedure with automated consideration of process variation. The Space Reduction Method based on Taguchi's DOE(Design Of Experiment) is used as a general optimization tool in this study. The computational experimental verification of the methodology was partially carried out for a can model of Cavallero Plastics Incorporation, U. S. A. Applied to production, this study will be of immense value to companies in reducing the product development time and enhancing the product quality.