Earticle

Kriging model is widely used as design DACE(analysis and computer experiments) model in the field of engineering design to accomplish computationally feasible design optimization. In this paper, the optimization of gate valve was performed using Kriging based approximation model. The DACE modeling, known as the one of Kriging interpolation, is introduced to obtain the surrogate approximation model of the function. In addition, we describe the definition, the prediction function and the algorithm of Kriging method and examine the accuracy of Kriging by using validation method.

In practical design process, designer needs to find an optimal solution by using full factorial discrete combination, rather than by using optimization algorithm considering continuous design variables. So, ANOVA(Analysis of Variance) based on an orthogonal array, i.e. Taguchi method, has been widely used in most parts of industry area. However, the Taguchi method is limited for the shape optimization by using CAE, because the multi-level and multi-objective optimization can't be carried out simultaneously. In this study, a combined method was proposed taking into account of multi-level computational orthogonal array and TOPSIS(Technique for Order preference by Similarity to Ideal Solution), which is known as a classical method of multiple attribute decision making and enables to solve various decision making or selection problems in an aspect of multi-objective optimization. The proposed method was applied to a case study of the multi-level shape optimization of lower arm used to automobile parts, and the design space was explored via an efficient application of the related CAE tools. The multi-level shape optimization was performed sequentially by applying both of the neural network model generated from seven-level four-factor computational orthogonal array and the TOPSIS. The weight and maximum stress of the lower arm, as the objective functions for the multi-level shape optimization, showed an improvement of 0.07% and 17.89%, respectively. In addition, the number of CAE carried out for the shape optimization was only 55 times in comparison to full factorial method necessary to 2,401 times.

The micro barrier rip array structures have been applied in a variety of areas including as privacy films, micro heat sinks, touch panel and optical waveguide. The increased aspect ratio (AR) of barrier rip array structures is required in order to increase the efficiency and performance of these products. There are several problems such as burr, defect of surface roughness and deformation and breakage of barrier rip structure with machining high-aspect ratio micro barrier rip array structure using orthogonal cutting method. It is essential to develop technological methods to solve these problems. The optimum machining conditions for machining micro barrier rip array structures having high-aspect ratio were determined according to lengths ($200{\mu}m$ and $600{\mu}m$) and shape angles ($2.89^{\circ}$ and $0^{\circ}$) of diamond tool, overlapped cutting depths ($5{\mu}m$ and $10{\mu}m$), feed rates (100 mm/s) and three machining processes. Based on the optimum machining conditions, micro barrier rib array structures having aspect ratio 30 was machined in this study.

본 연구에서는 부유식 10MW급 해상풍력발전기에 설치하기 위해 설계된 탈착형 계류 시스템인 Fairlead Chain Stopper (FCS)에 대해 직교배열실험법 (Orthogonal Array Design, OAD)을 이용한 최소중량설계와 민 감도 평가를 수행하였다. OAD에서 FCS의 주요 구성품의 두께 치수는 설계인자로 고려하였고, 응답치는 중량과 강도성능으로 선정하였다. OAD의 실험행렬 탐색 및 구성의 적합성은 반응표면모델을 생성하여 근사화 정확도의 평가를 통해 수행하였다. FCS의 최소중량설계은 OAD의 최상 설계안의 결과로부터 결정되었고, 민감도 평가를 통해 응답치 별로 영향도가 높은 설계인자가 파악되었다.

In this study, a minimum weight design and sensitivity analysis were conducted for the Fairlead Chain Stopper (FCS), a detachable mooring system designed for application to a 10 MW-class floating offshore wind turbine. The Orthogonal Array Design (OAD) was employed to systematically evaluate the influence of design variables. In the OAD, the thickness dimensions of the primary components of the FCS were selected as design factors, while the responses were defined as structural weight and strength performances. The suitability of the OAD experimental matrix configuration was verified by constructing a response surface model and assessing its approximation accuracy. The minimum weight design of the FCS was determined based on the optimal configuration derived from the OAD results. Furthermore, through sensitivity analysis, the design factors with the most significant effect on each response were identified.

본 논문은 다양한 설계하중조건 상태에서 자동채염기 구조설계의 성능분석과 개선을 위해 실험계획법을 이용 한 설계민감도 평가와 대리모델의 특성에 대한 비교연구를 수행하였다. 실험계획법은 수치해석 기반의 직교배열설계 방법을 이용하였다. 설계인자는 주요 구조부재의 두께치수 변수를 고려하였고, 응답치는 중량과 강도성능을 선정하였 다. 직교배열실험을 통해 설계인자 별 응답치에 대한 정량적인 영향도를 분석하였다. 또한 최소의 중량증감으로 구조 성능을 개선할 수 있는 최적의 설계조건을 탐색하였다. 직교배열실험 결과를 이용하여 반응표면모델, 크리깅모델, 그 리고 체비쇼프 직교 다항식과 같은 다양한 대리모델을 생성하였다. 대리모델의 결과를 통해 직교배열실험 결과의 타 당성을 검증하였다. 자동채염기 구조설계 공간 탐색에는 반응표면모델이 가장 적합한 대리모델로 평가되었다.

The paper deals with comparative study of characteristics of surrogate models and sensitivity evaluation using design of experiments in order to enhance and analysis the structure design of an automatic salt collector under various design load conditions. Orthogonal array design based on numerical analysis was used for the design of experiments. The thickness sizing variables of main structure member were considered the design factors, and the output responses were selected from the strength performances as well as the weight. The quantitative effects on responses for each design factor were evaluated from the orthogonal array experiment. Optimum design case was also identified to improve the strength performances with weight minimization. Using the orthogonal array experiment. various surrogate models such as response surface model, Kriging model, and Chebyshev orthogonal polynomial were generated. The orthogonal array experiment results were validated by the surrogate modeling results. The most suitable surrogate model was the response surface model for the exploration of design space of the automatic salt collector.

본 연구에서는 해양플랜트의 플로트오버 설치 작업을 위해 개발된 능동형 갑판지지 프레임(Deck support frame, DSF)의 구조설계에 대해 직교배열실험 방법을 이용한 민감도해석과 다양한 근사모델의 적용에 따른 설계공간 의 근사화 특성에 관한 비교연구를 수행하였다. 본 연구의 목적은 효율적인 최적설계안 탐색과 높은 정확도의 근사모델 을 생성할 수 있는 직교배열실험 기반의 설계 방법론을 제안하는 것이다. 설계인자는 주요 구조부재의 두께 치수를 적용 하였고, 응답함수는 중량과 강도성능을 선정하였다. 직교배열실험을 이용하여 설계인자 별 응답함수에 대해 정량적인 영향도가 분석되었고, 최소중량설계를 실현할 수 있는 최상 설계조건이 탐색되었다. 직교배열실험 결과로부터 반응표면 모델, 크리깅 모델, 체비쇼프 직교 다항식 모델, 그리고 방사기저함수 신경망 모델과 같은 다양한 근사모델이 생성되었 다. 근사모델의 결과를 통해 직교배열실험 결과의 타당성을 검증하였으며, 능동형 DSF의 설계공간에 대해 방사기저함 수 신경망 모델이 가장 높은 정확도로 근사화할 수 있는 것으로 나타났다.

The paper deals with comparative study for characteristics of approximation of design space according to various approximate models and sensitivity analysis using orthogonal array experiments in structure design of active type DSF which was developed for float-over installation of offshore plant. This study aims to propose the orthogonal array experiments based design methodology which is able to efficiently explore an optimum design case and to generate the accurate approximate model. Thickness sizes of main structure member were applied to the design factors, and output responses were considered structure weight and strength performances. Quantitative effects on the output responses for each design factor were evaluated using the orthogonal array experiment. Best design case was also identified to improve the structure design with weight minimization. From the orthogonal array experiment results, various approximate models such as response surface model, Kriging model, Chebyshev orthogonal polynomial model, and radial basis function based neural network model were generated. The experiment results from orthogonal array method were validated by the approximate modeling results. It was found that the radial basis function based neural network model among the approximate models was able to approximate the design space of the active type DSF with the highest accuracy.

타구치 직교배열표를 활용하여 마이크로스트립 패치 안테나 설계를 효율적으로 수행 가능한지를 분석하였다. 비교 및 분석을 위하여 U-슬롯 마이크로스트립 패치 안테나에서 U-슬롯의 모양과 변형된 급전부의 요소를 파라미터로 정했다. 해당 파라미터들의 스윕을 통해 도출된 모든 시뮬레이션의 결과와 타구치의 직교배열표를 이용하여 도출된 축소 시뮬레이션 결과를 비교분석하였다. 파라미터 스윕을 이용하여 진행된 19,683회의 시뮬레이션을 타구치의 직교배열표 를 이용한 27번의 시뮬레이션으로 대폭 축소하였으며, 파라미터 스윕과 직교배열표를 이용한 시뮬레이션의 평균 10dB 대역폭은 3.7%의 오차를 가진다. 따라서, 시뮬레이션 횟수를 줄이고도 효율적으로 안테나 파라미터 특성을 파악할 수 있음을 확인했다.

This paper is analysis on usefulness of Microstrip patch antenna design using Taguchi's Orthogonal array. For comparison, the shape of U-slot and Feed line elements are decided as a parameter in Microstrip patch antenna. And all the possible result of 19,683 times simulation using parameter sweep and the result of Taguchi's orthogonal arrays are compared. The simulation of Parameter sweep and Orthogonal arrays has 3.7% error on 10dB Bandwidth. Finally, It is identified that 19,683 times parameter sweep simulation can be reduced to 27 times with Taguchi's orthogonal arrays but still it represents antenna parameter characters well.

Orthogonal array-based Latin hypercube designs (OALHDs) were constructed for four input variables computer experiments. The proposed designs have some advantages over the random Latin hypercube designs in terms of better space-filling properties and maximin distance criterion employed in the construction. There is a link between Graeco-Latin squares and orthogonal arrays (OAs). Graeco-Latin squares are two mutually orthogonal Latin squares of the same order such that when one is superimposed on the other, each symbol in the body of one square appears together with each symbol in the body of the other exactly once. This method is fast and straightforward to implement. In this paper, orthogonal arrays, OA (25, 4, 5, 2) and OA (49, 4, 7, 2) were generated from Graeco-Latin square of orders 5 and 7 and the orthogonal arrays generated were used to construct OA(25, 4)LHD and OA(49, 4)LHD for use in a computer experiment that involves only four input variables. The OALHDs constructed have better space-filling properties. MATLAB 2012a package was used for the development of the program that constructs the OALHDs in this paper.

Rice bran and peptone were found to be the best carbon source and nitrogen sources for the production of carboxymethylcellulase (CMCase) by P . aquimaris LBH-10. Optimal conditions for production of CMCase such as concentrations of carbon and nitrogen sources, initial pH of medium and temperature were investigated using L25(53)-orthogonal array method with five distinct levels. The highest production of CMCase by P . aquimaris LBH-10 was 371.7 u/ml from 5.0% (w/v) rice bran and 3.0% (w/v) peptone under initial pH of 8.0 and temperature of 30℃. The optimal concentration of mineral salts for the highest production of CMCase from P . aquimaris LBH-10 using Orthogonal array were found to 0.00％ K2HPO4, 0.05％ NaCl, 0.01％ MgSO4·7H2O and 0.03％ (NH4)2SO4. Under these conditions, optimal agitation speed and aeration rate for the production of CMCase by P . aquimaris LBH-10 in a 7L bioreactor was 300 rpm and 1.0 vvm.

The gene coding for carboxymethylcellulase (CMCase) of B. amyoliquefaciens DL-3 was isolated and cloned in E. coli JM109F. Rice bran and tryptone were chosen as carbon and nitrogen sources for production of CMCase by E. coli JM109F, respectively. Optimal conditions such as concentrations of carbon sources and nitrogen sources, initial pH of medium, and temperature for production of CMCase were investigated using L25(5)3 - orthogonal array method with five distinct levels and three factors. The highest production of CMCase was 1,314.2 U/ml from 5.0% (w/v) rice bran and 0.1% (w/v) tryptone under initial pH of 7.5 and 37℃. Optimal conditions of salts for production of CMCase were also investigated using L25(5)4. The highest production of CMCase E. coli JM109F was 1,514.6 U/ml with 0.5% (w/v) K2HPO4, 0.025% (w/v) NaCl, 0.04% MgSO4․7H2O and 0.24%(w/v) (NH4)2SO4.

Rice bran and peptone were the best combination of carbon and nitrogen sources for the production of CMCase by a psychrophilic marine bacterium, Psychrobacter aquimaris LBH-10. Based on intuitive analysis and statistical calculations using data from an L25 (54) orthogonal array experiment with four factors and five level of each factor, optimal concentrations of rice bran and peptone for the production of avicelase and CMCase by P. aquimaris LBH-10 were found to be 50.0 and 3.0 g/L, respectively, whereas those of FPase were 100.0 and 4.0 g/L, respectively. Optimal initial pHs of the medium for production of avicelase and CMCase were 8.0, whereas that of FPase was found to be 9.0. The optimal temperature for the production of avicelase, CMCase, and FPase was 30℃. According to R values calculated from results of the orthogonal array experiment, the most important factor for the production of cellualses by P. aquimaris LBH-10 was found to be rice bran. The optimal agitation speed and aeration rate for the production of CMCase in a 7 L bioreactor were 300 rpm and 1.0 vv. The highest production of avicelase, CMCase, and FPase from 50.0 g/L rice bran and 3.0 g/L peptone in a 100 L bioreactor under optimized conditions was 83.2, 388.7, and 75.4 U/mL, respectively.

Optimal conditions for production of the carboxymethycellulase (CMCase) and filterpaperase (FPase) by E. coli pTDL-3 were investigated in a 7L bioreactor using an orthogonal array method. On basis of intuitive analysis and statistical calculations using data, significance of aeration rate on production of the CMCase by E. coli pTDL-3 was higher than that of agitation speed on production of the CMCase as well as for production of the FPase. Optimal agitation speed and aeration rate for the production of CMCase were found to be 200 rpm and 1.0 vvm in a 7 L bioreactor. Productivity of the CMCase by E. coli pTDL-3 from 5.0% (w/v) rice bran and 0.1% (w/v) tryptone under optimized conditions was 544.4 U/ml in a 100 L bioreactor with an inner pressure of 0.2 kgf/cm2.

A microorganism hydrolyzing carboxymethylcellulose (CMC) was isolated from seawater, identified as Bacillus atrophaeus by analyses of 16S rDNA sequences, and named as B. atrophaeus LBH-18. Rice bran and ammonium peptone were the best combination of carbon and nitrogen sources for the production of the CMCase by B. atrophaeus LBH-18. Based on intuitive analysis and statistical calculations using data from an L25(35) orthogonal design experiment with three factors of rice bran, peptone, and initial pH of medium, rice bran was found to be the most important factor for production of the CMCase by B. atrophaeus LBH-18. Optimal concentrations of rice bran and peptone for production of CMCase were found to be 5.0% and 0.5%, respectively. Optimal initial pH of medium and temperature were 7.0 and 30℃. Effect of salts was also investigated using an orthogonal array method. Potassium phosphate from four salts in the medium was found to be the most important factor for production of the CMCase by B. atrophaeus LBH-18. Productivity of the CMCase by B. atrophaeus LBH-18 was about 120 U/ml under optimized conditions.

The optimal conditions for the mass production of carboxymethylcellulase (CMCase) of Bacillus amyloliquefaciens by a recombinant E. coli JM109/DL-3 were established in this study using an orthogonal array method. Rice bran and tryptone were found to be the best carbon and nitrogen sources for the production of CMCase by E. coli JM109/DL-3. The optimal concentrations of rice bran and tryptone and the initial pH for the production of CMCase were 50.0, 2.5 g/L, and 7.5, respectively. The optimal concentrations of K2HPO4, NaCl, MgSO4·7H2O, and (NH4)2SO4 in the medium for the production of CMCase by E. coli JM109/DL-3 were 5.0, 1.00, 0.40, and 0.60 g/L. The optimal agitation speed and aeration for cell growth of E. coli JM109/DL-3 in 7 L bioreactors were 500 rpm and 1.0 vvm, whereas those for the production of CMCase were 400 rpm and 1.0 vvm. The optimal inner pressure for cell growth of E. coli JM109/DL-3 in 100 L bioreactors was found to be 0.8 kgf/cm2, whereas that for the production of CMCase was 0.6 kgf/cm2. The production of CMCase with an inner pressure of 0.6 kgf/cm2 was 1.36 times higher than that without an inner pressure.

A microorganism isolated from seawater, which utilized rice bran as a substrate and produced carboxymethylcellulase (CMCase), was identified as Bacillus atrophaeus and designated B. atrophaeus LBH-18. Rice bran and peptone were found to be the best combination of carbon and nitrogen sources for cell growth of B. atrophaeus LBH-18 and the production of CMCase. Based on intuitive analysis and statistical calculations using data from an L25 (53) orthogonal array experiment with four factors and five level of each factor, the optimal concentrations of rice bran and peptone for cell growth of B. atropphaeus LBH-18 were 75.0 and 10.0 g/L, respectively, whereas those for the production of CMCase were 50.0 and 5.0 g/L, respectively. The optimal pH of the medium for cell growth were 6.0, whereas those for the production of CMCa se were 7.0. According to R values calculated from results of an orthogonal array experiment, the most important factor for cell growth as well as the production of CMCase by B. atrophaeus LBH-18 was found to be rice bran. The optimal temperature for cell growth for cell growth as well as the production of CMCase was 30℃.

This experiment is concerned with optimization of culture medium by C. lytica LBH-14. The one-factor-at-a-time method was used to investigate the effect of carbon & nitrogen sources, and initial pH on production of carboxymethylcellulase (CMCase) and cellobiase by C. lytica LBH-14. Base on the result of one-factor-at-a-time experiment, L25-53 was performed to measure combined effects of carbon source & nitrogen source, and initial pH on production of CMCase and cellobiase. Optimal conditions for production of CMCase were 10.0% (w/v) rice bran, 0.75% (w/v) ammonium nitrate, and initial pH 6.00, whereas those of cellobiase were 10.0% rice bran, 0.50% ammonium nitrate, and the initial pH of 7.50. On basis of intuitive analysis and statistical calculations using data from an orthogonal experiment, ammonium nitrate was found to be the most important factor for production of the CMCase by C. lytica LBH-14, whereas the most important factor for production of cellobiase was rice bran.

최근 소프트웨어 가 점 점 복잡해 짐 에 따라 다양한 상황에 대한 테스트의 중요도도 함께 증가하지만, 다양한 상황을 모두 고려하여 테스트하는 것은 많은 시간과 비용을 요구한다. 본 논문에서는 이러한 복잡한 시스템의 테스트를 위해 Orthogonal Array와 Equivalence Class 기법을 이용하여 test suite의 중복성을 낮추는 효율적인 test set을 생성하는 기법을 제안한다. 이렇게 제안된 기법을 OMA DRM(Digital Rights Management) System에 적용한 사례를 통해 기법의 우수성을 보인다.

최근 소프트웨어 가 점 점 복잡해 짐 에 따라 다양한 상황에 대한 테스트의 중요도도 함께 증가하지만, 다양한 상황을 모두 고려하여 테스트하는 것은 많은 시간과 비용을 요구한다. 본 논문에서는 이러한 복잡한 시스템의 테스트를 위해 Orthogonal Array와 Equivalence Class 기법을 이용하여 test suite의 중복성을 낮추는 효율적인 test set을 생성하는 기법을 제안한다. 이렇게 제안된 기법을 OMA DRM(Digital Rights Management) System에 적용한 사례를 통해 기법의 우수성을 보인다.

In onshore and offshore plant engineering, a broad use of pipe system have been achieved and accordingly related technologies has been developed especially in the field of flow control valves. The aim of this study is to suggest the quadruple offset butterfly valve for bi-directional applications which show equivalent operating torque characteristics of the triple offset butterfly valve. Seat design parameters for the quadruple offset butterfly valve are determined by the proposed method utilizing both ANOVA (analysis of variance) and the orthogonal array. Through additive model considering the effect of design parameters on seating torque, mean estimation is performed and thus its optimization results are verified by design of experiment results. The insight obtained from the present study is beneficial for valve design engineers to develop reliable and integrated design of the quadruple offset butterfly valve.