• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.366-375
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• 2006

In this paper, it is intended to introduce a method to solve multi-objective optimization problems and to evaluate its performance. In order to verify the performance of this method it is applied for a vertical roller mill for Portland cement. A design process is defined with the compromise decision support problem concept and a design process consists of two steps: the design of experiments and mathematical programming. In this process, a designer decides an object that the objective function is going to pursuit and a non-linear optimization is performed composing objective constraints with practical constraints. In this method, response surfaces are used to model objectives (stress, deflection and weight) and the optimization is performed for each of the objectives while handling the remaining ones as constraints. The response surfaces are constructed using orthogonal polynomials, and orthogonal array as design of experiment, with analysis of variance for variable selection. In addition, it establishes the relative influence of the design variables in the objectives variability. The constrained optimization problems are solved using sequential quadratic programming. From the results, it is found that the method in this paper is a very effective and powerful for the multi-objective optimization of various practical design problems. It provides, moreover, a reference of design to judge the amount of excess or shortage from the final object.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2150-2158
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• 2002

A recent research and development has the requirement for the optimization to shorten design time of modified or new product model and to obtain more precise engineering solution. General optimization problem must consider many conflicted objective functions simultaneously. Multi-objective optimization treats the multiple objective functions and constraints with design change. But, real engineering problem doesn't describe accurate constraint and objective function owing to the limit of representation. Therefore this study applies variance analysis on the basis of structure analysis and DOE to the vertical roller mill fur portland cement and proposed statistical design model to evaluate the effect of structural modification with design change by performing practical multi-objective optimization considering mass, stress and deflection.

• Journal of Advanced Marine Engineering and Technology
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• 제31권3호
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• pp.215-223
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• 2007

When the propulsion shafting system of marine diesel engine is designed. the vibratory stresses on shafts should be reviewed and be satisfied with limits which are laid down by classification societies In addition. the torsional vibration aspects for crankshaft of main engine are requested to be checked by engine designers. Especially. for the 4, 5, and 6-cylinder engines. the 2nd order moment compensator(s) may be installed to compensate the external moments of engine and not to excite the hull girder vibration. This moment compensator which is mounted on fore and/or after-end of engine is driven by the roller chain drive for some of MAN 2-stroke diesel engines. While the engine is running, the roller chain Is worn down, which causes the extension of roller chain. The chain therefore should be checked and tightened by periods in order to keep its functionality. However. when the torsional angular acceleration of chain drive exceeds the certain limit. the chain will suffer the excessive slack and transverse vibration. This may cause fatigue, wear or damage on the chain and the chain ultimately may be broken. The research object of this thesis is to review factors which affect the angular acceleration of chain drive and to find out how to decrease the angular acceleration of driving chain by checking factors which have a major contribution to acceleration reduction using the statistical method of DOE(design of experiment), correlation analysis and regression analysis methods.

• 터널과지하공간
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• 제32권6호
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• pp.386-396
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• 2022

로드헤더에 미치는 변수의 영향력을 분석하기 위해 픽커터 절삭시험 관련 참고문헌들을 조사하였고, 수록된 데이터들을 수집하였다. 입력 인자는 일축압축강도, 절삭 깊이, 절삭 간격, 받음각, 비틀림각, 출력 인자는 비에너지, 절삭력, 수직력으로 결정했다. 입력 인자와 출력 인자로 분류 후 실험계획법을 작성하였고 분산분석을 이용해 변수들에 대한 기여도를 조사하였다. 그 결과, 절삭력과 비에너지에 가장 큰 영향을 미치는 요인은 일축압축강도와 절삭 간격으로 분석되었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.638-641
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• 2008

Computational investigation was conducted to study the effects of the shape parameter of shroud on the performance of the outdoor unit of an air-conditioners. For this study the Design of Experiment(4-factor 3-level) was created and the an automatic program was composed using VBA to reduce the load of pre-process for CFD. The estimated mathematical equation was produced from this analysis and it was found that the gap between fan and shroud affects more heavily than the other parameters. As a result, the composition of the best parameters was verified that its flow rate was increased by 10 percents and sound pressure level was reduced by 1.2 dBA compare with the worst. And finally, a kind of Propeller fan with blades which were attached to the shroud, so-called 'ProBeller Fan' was introduced in this study.

• 한국산학기술학회논문지
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• 제13권10호
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• pp.4378-4384
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• 2012

LED 칩 패키징에서 다이 본딩은 웨이퍼에서 분할된 다이를 리드 프레임에 접착제로 고정시켜 칩이 다음 공정을 견딜 수 있는 충분한 강도를 제공하는 중요한 공정이다. 본 논문에서는 PLCC 구조 LED 패키지 프레임에 소형 제너 다이오드를 부착하는 다이 본딩 공정능력의 최적화를 위하여 공정에 영향을 미치는 여러 인자를 분석하여 반응표면분석법을 적용하여 그 결과를 도출하였다. 인자를 분석하여 5인자 3수준 4반응치를 고려하여 실험계획법을 수립하였으며, 그 결과 모든 반응치의 목표를 만족하는 최적 조건을 확보할 수 있었다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.407-410
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• 2007

In the RRH (Radio Remote Head) of a WCDMA Node B System, an HPA (High Power Amplifier) is used in order to amplify the transmission RF signal. Upon designing an HPA, the design requirements demand that the intermodulation characteristics are optimized during design and that the stability of the characteristics is maintained in the field. In this DOE (Design of Experiments) research, a few vital factors that affect intermodulation characteristics were first selected; then, an optimal solution was produced for high reliability in a noisy environment in the field by employing the Taguchi Method, a statistical method used for a robust design. Furthermore, by employing HALT(High Accelerated Life Test) during the verification test, this experiment has verified that an HPA that was designed using the Taguchi Method proved to be a far more robust design than an HPA that was designed without using the method.

• 대한기계학회논문집A
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• 제33권10호
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• pp.1132-1138
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• 2009

The spring constants of primary suspensions for a railway vehicle are optimized by a robust design process, in which the response surface models(RSMs) of their dynamic responses are constructed via the design of experiment(DOE). The robust design process requires an intensive computation to evaluate exactly a probabilistic feasibility for the robustness of dynamic responses with their probabilistic variances for the railway vehicle. In order to overcome the computational process, the process capability index $C_{pk}$ is introduced which enables not only to show the mean value and the scattering of the product quality to a certain extent, but also to normalize the objective functions irrespective of various different dimensions. This robust design, consequently, becomes to optimize the $C_{pk}$ subjected to constraints, i.e. 2, satisfying six sigma. The proposed method shows not only an improvement of some $C_{pk}$ violating the constraints obtained by the conventional optimization, but also a significant decrease of the variance of the $C_{pk}$.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.51-57
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• 2019

구리 표면을 대기 중의 산화로부터 보호하기 위해서 아르곤(Ar)과 질소($N_2$) 가스를 이용하는 two-step플라즈마 공정으로 산화 방지층인 구리 질화물 패시베이션 형성을 연구하였다. Ar 플라즈마는 구리 표면에 존재하는 이물질을 제거하는 동시에 표면을 활성화시켜 다음 단계에서 진행되는 $N_2$ 플라즈마 공정 시 질소 원자와 구리의 반응을 촉진시키는 역할을 수행한다. 본 연구에서는 two-step 플라즈마 공정 중 Ar 플라즈마 공정 조건이 구리 질화물 패시베이션 형성에 미치는 영향을 실험계획법의 완전요인설계를 통하여 분석하였다. XPS 분석에 의하면 Ar 플라즈마 공정 시 낮은 RF 파워와 압력을 사용할 경우 구리 산화물 피크(peak) 면적은 감소하고, 반대로 구리 질화물(Cu4N, Cu3N) 피크 면적은 증가하였다. Ar 플라즈마 공정 시 구리 질화물 형성의 주 효과는 RF 파워로 나타났으며 플라즈마 공정 변수간 교호작용은 거의 없었다.

• 한국항공우주학회지
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• 제39권1호
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• pp.50-55
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• 2011

본 연구에서는 고고도 장기 체공 항공기 날개의 스팬과 주날개보의 형상을 설계변수로 동시에 고려하는 공력-구조 동시 설계를 수행하였다. 이 때 공기역학적 성능 최대화와 중량 최소화를 한 번에 수행하기 위해 다목적 최적화를 이용하였다. 설계 대상이 된 날개는 구조적 대변형이 발생되므로 전산유체역학과 유한요소법을 이용하여 비선형 정적 공탄성 해석을 수행하였다. 설계를 위한 해석에 요구되는 계산 비용을 감소시키기 위해 반응면을 구성하였으며 이를 위해 실험계획법이 이용되었다. 또한 본 연구에서는 대변형이 발생되지 않은 형상과 대변형이 발생한 형상의 공력 성능을 비교하여 대변형이 발생하는 경우 설계를 위해 반드시 변형이 고려되어야 함을 검증하였다.