• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1173-1176
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• 1995

We design and analyze two type stators for brushless DC linear motors by the experiment and the computational analysis. For a U-shape stator, the maximum manetic flux density by the finite element method(FEM) is large than that by the experiment by 1.0~2.2%. The result by the FEM is so accurate that it can be applied to the geometric design for the optimization. To increase the maximum magnetic flux density, we suggest an improved stator and analyze it by the 3-D and 2-D models. The maximum magnetic flux density of the improved stator is large than that of the U-Shape stator by 2.7%. Considering the size of the improved stator and maximum magnetic flux density, we determine that the optimized thickness is 5mm for a given specification.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.352-355
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• 2004

The objective of this work is to develop a new design method to find optimal coils, especially the optimal coil configuration of an optical pickup actuator. In designing actuator coils, the developed Lorenz force in the coils along the desired direction should be made as large as possible while forces and torques in other directions should be made as small as possible. The design methodology we are developing is a systematic approach that can generate optimal coil configurations for given permanent magnet configurations. To consider the best coil configuration among all feasible coil configurations, we formulate the design problem as a topology optimization of a coil. The present formulation for coil design is noble in the sense that the existing topology optimization is mainly concerned with the design of yokes and permanent magnets and that the optimization of actuator coils is so far limited within shape or size optimization. Though the present design methodology applies to any problem, the specific design example considered is the design of fine-pattern tracking and focusing coils.

• 대한기계학회논문집A
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• 제33권8호
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• pp.793-798
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• 2009

In this paper, the simulation and optimization of SRH (Surface Relief Hologram) masks for printing LCD gate patterns using TIR (Total Internal Reflection) holographic lithography was investigated. A simulation and optimization algorithm based on SDTA (Scalar Diffraction Theory Analysis) method was developed. The accuracy of the algorithm was compared to that of the RCWA (Rigorous Coupled Wave Analysis) method for estimating the Fresnel diffraction pattern of Cr amplitude masks for the given system geometry. In addition, the results from the optimization algorithm were validated experimentally. It was found that one to the most important conditions for the fabrication of SRH masks is to avoid nonlinear shape distortions of the resulting grating. These distortions can be avoided by designing SRH masks with recorded gratings having small aspect ratios of width versus depth. The optimum gap size between the Cr and SRH masks was found using the optimization algorithm. A printed LCD gate pattern with a minimum line width of $1.5{\mu}m$ exposed using the optimized SRH mask was experimentally demonstrated.

• 한국기계가공학회지
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• 제19권2호
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• pp.103-110
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• 2020

Riveting is mainly used to assemble the aircraft fuselage. An average of 2~3 workers is needed to assemble an aircraft fuselage consisting of various size frames by riveting. In this study, a riveting process that enables one-person operation using an automated C-frame riveting machine was proposed for improving the efficiency of productivity. The proposed process was verified stability through structural analysis. In the range that can maintain structural stability, panel thickness of the riveting machine and shape were modified to optimizing the shape for reducing the weight of the riveting process. The structural analysis was performed by software ANSYS workbench 19.2. The optimized riveting machine was reduced by 257kg compared to the existing model.

• 재활복지공학회논문지
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• 제10권1호
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• pp.65-72
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• 2016

본 논문은 계단 보행 조건에서 작동할 수 있는 능동형 대퇴의지를 설계하고 구조 최적화를 통해 경량화를 진행하는 것을 목적으로 한다. 계단 보행 시 무릎에 걸리는 토크는 일반 보행에 비해 크므로 능동형 상대적으로 큰 토크를 낼 수 있는 동력 시스템이 필요하다. 또한 의지의 무게는 사용자의 착용감과 피로감과 연관이 되므로 의지의 경량화 설계 또한 필수적이다. 계단 보행 시 필요한 토크를 만들어내고 경량화와 소형화 구조를 적용하기 위해 플랫형 BLDC 모터를 사용하였다. 다양한 감속 장치를 이용해 필요 토크를 생성하고 작동각도 및 속도를 만족할 수 있게 감속비를 선정하였다. 구조 및 구동부 설계가 완료된 후 최적화를 통해 구조 경량화를 수행하였다. 계단 보행 시 나타나는 하중 조건을 고려하여 최적화를 수행하였으며, 해석 및 실험을 통해 최적화된 구조의 안정성을 검증하였다. 결과적으로 구조물의 강성은 유지하면서 위상 최적화와 형상 최적화를 통하여 무게를 감량하였으며, 공간 효율이 좋아졌다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.720-724
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• 2000

In this paper, we introduce a seamlessly integrated CAD-based design system (DS) for CAD modeling, engineering analysis, and optimal design which has been developed in CCED at KAIST, The key points of this integrating philosophy are to make full use of a parametric CAD program as the platform of integration and to adopt finite difference method for design sensitivity analysis in optimization process to get robustness and versatility. Design variables are directly selected by clicking CAD model parameters and all the analysis and design activities are menu-driven. This integrated program, named as DS/FDM, runs on Windows NT or Unix and FE analyses are performed at a remote Unix-workstation for multiple users. Application examples include shape optimal design of a belt clip that fits onto a portable electronic device and a bracket to show performance of DS/FDM with shell and tetra solid elements. This software is found efficient and effective fur shape design and size design of engineering structures.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.653-658
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• 2015

This paper deals with an efficient optimization design method of a compact ultra wideband (UWB) filter which can improve the characteristics of the filter. The Evolution Strategy (ES) algorithm is adopted for the optimization and modified to suppress the ripple by inserting an additional step to the ES scheme. The algorithm has the ability to control the ripple of an insertion loss in a passband as a modified approach. During the modified ES, a structure of initial shape is changed a lot, while includes the stepped impedance (SI) and the composite right/left handed transmission line (CRLH-TL). And an optimized filter satisfies the UWB specifications on the stopband and passband with an acceptable insertion loss. The filter achieves a much developed shape, the size of $15{\times}14mm$, the 3dB bandwidth from 2.7 to 10.8GHz, the flat insertion-loss less than 1dB, the wide stopband with 12~20GHz, and an acceptable return loss.

• Computers and Concrete
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• 제28권5호
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• pp.465-478
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• 2021

On the premise of ensuring that the static performance of the concrete spreader is met, the first-order natural frequency of the concrete spreader is increased, and the weight of the main beam is reduced. ANSYS is used as an analysis tool to perform modal analysis on the concrete spreader. The natural frequency, mode shape and modal test verification will be obtained to ensure the accuracy of finite element model analysis. Using the ANSYS designxplorer module, the size of the main beam is set, and the response surface model between the parameter variables and the optimization objective is established according to the experimental design points. Screening algorithm and MOGA algorithm are used to multi-optimize the stress, first-order natural frequency and girder weight, and the optimal solution is obtained by comparison. The results of modal analysis are consistent with those of the experiment, and a set of optimal solutions is obtained through the optimization algorithm. The optimal solution obtained can meet the purpose of increasing the first-order natural frequency of the concrete spreader and reducing the weight of the main beam under the premise of ensuring the overall dynamic and static performance of the concrete spreader.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1246-1253
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• 2007

The recent issue of optical pickup actuators is to apply optical storage devices to mobile devices such as a cellular phone and PDA. It requires actuators to become smaller than conventional types. As the size becomes smaller, the magnetic force is reduced and the assembly of optical pickup actuators becomes more difficult. In addition, its dynamic characteristics are changed. In this paper, methods to improve magnetic forces and dynamic characteristics are suggested and the optimal result of the plate spring design is obtained. A diamond shape magnet and the fine pattern coil (FPC) are used to improve magnetic forces and damping elements are attached to decrease the peak magnitude of the mode instead of using structural damping, mostly for the purpose of improving the accuracy of the finite element simulation. To get more stable dynamic characteristics than conventional ones, a plate spring is applied to the optical pickup actuator and it is optimized with topology and parameter optimization to obtain the concept and the detail design, respectively.

• Wind and Structures
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• 제20권4호
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• pp.489-508
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• 2015

In this paper, a novel methodology is proposed to obtain optimum location of outriggers. The method utilizes genetic algorithm (GA) for shape and size optimization of outrigger-braced tall structures. In spite of previous studies (simplified methods), current study is based on exact modeling of the structure in a computer program developed on Matlab in conjunction with OpenSees. In addition to that, exact wind loading distribution is calculated in accordance with ASCE 7-10. This is novel since in previous studies wind loading distributions were assumed to be uniform or triangular. Also, a new penalty coefficient is proposed which is suitable for optimization of tall buildings. Newly proposed penalty coefficient improves the performance of GA and results in a faster convergence. Optimum location and number of outriggers is investigated. Also, contribution of factors like central core and outrigger rigidity is assessed by analyzing several design examples. According to the results of analysis, exact wind load distribution and modeling of all structural elements, yields optimum designs which are in contrast of simplified methods results. For taller frames significant increase of wind pressure changes the optimum location of outriggers obtained by simplified methods. Ratio of optimum location to the height of the structure for minimizing weight and satisfying serviceability constraints is not a fixed value. Ratio highly depends on height of the structure, core and outriggers stiffness and lateral wind loading distribution.