• Composites Research
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• v.26 no.4
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• pp.207-212
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• 2013

In this study, the thickness optimization for uni-directional (UD) glass fiber reinforced polymer (GFRP) laminates of the spar cap of composite tidal blades was performed under the tip deflection constrains. The spar cap was composed of GFRP composites and carbon fiber reinforced polymer (CFRP) composites. The stress distributions in the blade as well as its material costs for the optimized results were additionally investigated. The optimized thickness was obtained by interacting a sequential quadratic programming (SQP) algorithm and an ABAQUS software to calculate an objective function. It was confirmed that the thickness of UD GFRP increased with a decrease of the restrained tip deflection when a thickness of UD CFRP laminates was constrained to 9 mm. The weight of the optimized spar-cap increased up to 96.2% while the maximum longitudinal tensile stress decreased up to 24.6%. The thickness of UD GFRP laminates increased with a decrease of the thickness of UD CFRP laminates when the tip deflection was constrained to 126.83 mm. The weight increased up to 40.1%, but the material cost decreased up to 16.97%. Finally, the relationships among the weight, internal tensile stress, and material costs were presented based on the optimized thicknesses of the spar cap.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.391-400
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• 2004

Within multimodal medical image registration techniques, which correlate different images and Provide integrated information, surface registration methods generally minimize the surface distance between two modalities. However, the features of two modalities acquired from one subject are similar. So, it can improve the accuracy of registration result to match two images based on optimization of both surface distance and shape feature. This research proposes a registration method which optimizes surface distance and surface curvature of two brain modalities. The registration process has two steps. First, surface information is extracted from the reference images and the test images. Next, the optimization process is performed. In the former step, the surface boundaries of regions of interest are extracted from the two modalities. And for the boundary of reference volume image, distance map and curvature map are generated. In the optimization step, a transformation minimizing both surface distance and surface curvature difference is determined by a cost function referring to the distance map and curvature map. The applying of the result transformation makes test volume be registered to reference volume. The suggested cost function makes possible a more robust and accurate registration result than that of the cost function using the surface distance only. Also, this research provides an efficient means for image analysis through volume visualization of the registration result.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.10-17
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• 2003

In this paper, genetic algorithm (GA)-based Thin Film Bulk Acoustic Resonator (FBAR) RF filter design technique is proposed. Since the BVD(Butterworth-Van Dyke) lumped element model is valid only around the resonance, FBAR filter design technique based on BVD circuit has an approximate error. Instead of using BVD model, optimizing filter design method utilizes an analytical electrical impedance equation of FBAR. The geometry of FBAR such as thickness of the piezoelectric layer and area which significantly affect the filter response is optimized by GA. US-PCS Rx Bandpass filter obtained by the proposed technique shows a better response comparing with the typical and BVD-based filter.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.270-276
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• 2012

In this study, thermally coupled distillation system and conventional two-column process were investigated for extractive distillation. The two processes were simulated and optimized using Aspen plus. Objective function for the optimization was energy consumption and optimization results to reduce energy consumption were used to get guidelines for design and operation for the two extractive distillation processes. Comparison of these two processes showed that thermally coupled distillation system provided better energy efficiency and lower capital cost than conventional distillation system.

• Journal of the KSME
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• v.31 no.1
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• pp.34-42
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• 1991

복잡한 형상의 서지 탱크를 CAEDS의 GEOMOD를 이용하여 내부의 리보까지 포함한 용기를 모델링하였으며, 설계 부피를 검사하고 GEOMOD와 GFEM 사이의 직접 데이터 교환을 통하여 구조 해석에 필요한 유한요소를 만들었다. 유한요소법에 최적화 이론을 적용하여 서지탱크의 두께 변화에 따른 응력의 설계 민감도를 구하였으며, 민감도를 근거로 보강 위치 및 국부적인 용기의 두께를 결정하였다. 유한요소법 프로그램(IFES, GFEM)과 솔리드 모델러(GEOMOD), 그리고 최적화 기법(IFES-Optimization)을 모두 통합하여, 최적 설계를 수행함으로써 반복되는 실험에 의한 시간과 경비를 줄임과 동시에 신뢰성 있는 설계방법 및 방향을 제시하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.9
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• pp.816-823
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• 2000

상위단계 합성에서 데이터 저장을 위한 메모리 할당 문제는 중요하게 다루어지는 영역의 하나이다. 이 논문에서는, 다중포트(multiport)메모리 할당 문제에 대한 새로운 방법을 제안한다. 문제의 복잡도를 줄이기 위해, 기존의 연구들은 요약하면, 두 단계의 과정으로 이루어지고 있다. 첫 번째 단계에서는 변수들을 몇 개씩 묶어서 하나의 메모리를 형성한다. (즉 메모리 최적화 문제를 푼다.) 두 번째 단계에서는 메모리들과 기능모듈들 간의 연결선을 최적화시킨다. (즉, 연결선 최적화 문제를 푼다) 이 경우 심각한 단점은 연결선의 비용을 최소화하는 데는 한계가 있다는 것이다. 다시 말해, 연결선의 비중이 점점 중요하게 되어지는 설계 추세에서 기존의 방법은 다중포트 메모리 사용을 통해 얻을 수 있는 연결선 최소화를 극대화하는데 한계가 있음을 뜻한다. 이를 극복하기 위해, 우리는 새로운 할당 방법을 제시한다. 구체적으로 먼저, 연결선 최소화를 해결하고, 그 다음에, 메모리 최적화를 시도한다. 또한 제안한 알고리즘은 연결선 최소화 과정 동안 다음 단계에서 결정될 메모리 비용도 적절히 고려한다. 우리는 다양한 실험을 통해, 우리의 제안한 방법이 기존의 연구보다 상당히 효율적인 것임을 보인다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1125-1130
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• 2017

The tooth shapes of serration-type and spline-type reactors are optimized using finite element methods to improve the working life of the part and to lower the stress concentration during rotation resulting from contact with the outer race for a reactor operating with $170^{\circ}C$ transmission oil. The results of thermal expansion analyses between an Al reactor and the steel outer race indicate that, before optimization, the gap between the two parts increases further as the serration-type reactor expands by 0.1 mm and the spline-type one strains by 0.08 mm. Because of shape optimization, a trapezoidal shape is obtained from the initial triangular serration and the rectangular spline of the two reactors. The maximum von Mises stress of the serration-type convertor decreased by 24.5 ％, and by 9.3 ％ for the spline-type convertor. In addition, there is a 13 ％ reduction in the axial thickness, as compared to the initially designed model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.905-913
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• 2017

In this work, a method of size optimization is proposed to maximize the natural frequency of a rod that consists of a hidden shape in one part and an exposed shape in the other. The frequency response function of a rod composed of two parts is predicted by using the frequency response functions of each of the parts instead of the shapes of the parts. The mass and stiffness matrices of the rod are obtained by using the mass and stiffness matrices of the equivalent vibration systems, which are obtained by applying the experimental modal analysis method to the frequency response functions of the parts. Through several numerical examples, the frequency response function obtained by using the proposed method is compared with that of a rod to validate the prediction method based on equivalent vibration systems. A size optimization problem is formulated for maximizing the first natural frequency of a combined rod, which is replaced with an equivalent vibration system, and a rod structure is optimized by using an optimization algorithm.

• 대한공업교육학회지
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• v.34 no.2
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• pp.321-330
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• 2009

This study presents the blow molding of injection stretch-blow molding process for PET bottle. The numerical analysis of the blow molding of PET bottle is considered in this paper using CAE with a view to minimize the thickness difference. In order to determine the design parameters and processing conditions in blow molding, it is very important to establish the numerical model with physical phenomenon. In this study, a shell model with thickness has been introduced for the purpose and blow simulations with 3-type blow process condition are carried out. The simulations resulted in the thickness distribution in good agreement with the physical phenomenon. Also, from the result of numerical analysis, we appropriately predicted the thickness distribution along the PET bottle wall and Using the result of numerical analysis we apply the preform design and blow molding process condition for optimization.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.477-485
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• 2012

Geometric configurations such as hull shape, wall thickness, stiffener layout, and type of construction materials are the key factors influencing the structural performance of pressure hulls. Traditional theoretical approach provides quick and acceptable solutions for the design of pressure hulls within specific geometric configuration and material. In this paper, alternative approaches that can be used to obtain optimal geometric shape, wall thickness, construction material configuration and stiffener layout of a pressure hull are presented. CAE(Computer Aided Engineering) based design optimization tools are utilized in order to obtain the required structural responses and optimal design parameters. Optimal elliptical meridional profile is determined for a cylindrical pressure hull design using metamodel-based optimization technique implemented in a fully-integrated parametric modeler-CAE platform in ANSYS. While the optimal composite laminate layup and the design of ring stiffener for a thin-walled pressure hull are obtained using gradient-based optimization method in OptiStruct. It is noted that the proposed alternative approaches are potentially effective for pressure hull design.