• ETRI Journal
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• v.14 no.4
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• pp.137-147
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• 1992

다중프로세서 컴퓨터시스팀의 성능은 시스팀 구성 요소인 하드웨어, 운영체제, 응용 프로그램의 특성에 매우 복잡하게 관련되어 있다. 시스팀 설계 단계에서 시스팀 구성요소에 대한 최적 형상을 결정하기 위하여 여러가지 설계대안에 대한 성능 한계를 구할 필요가 있다. 이를 위한 방법의 하나로 4-point bound 방법이 제시되었다. 본 논문은 pended protocol 로 동작하는 시스팀 버스 기반의 다중프로세서 시스팀의 성능 한계를 4-point bound 방법으로 분석한 것이다. 이를 위해 pended protocol의 동작 특성을 반영하는 작업부하를 정의하고, 캐시 적중률, 버스 동작 특성의 변화에 따른 다중프로세서 시스팀의 성능 한계를 예측 분석 한다.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.46-48
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• 2004

본 논문에서는 유한 요소법과 등가회로법을 이용하여 윤곽 진동형 압전 변압기의 특성을 해석하였으며 이를 통해 얻어진 결과를 기반으로 매칭 임피던스와 전기 및 기계적 결합 계수를 계산하였다. 전력 소자로서 사용되는 압전 변압기는 부하 등 특정 목적에 부합하는 정확한 설계가 필요하기 때문에 다중 목적 함수를 갖는 진화 전략을 이용하여 형상 최적화를 수행하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.549-558
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• 2012

A topology optimization method for phononic crystals is developed for the design of sound barriers, using the level set approach. Given a frequency and an incident wave to the phononic crystals, an optimal shape of periodic inclusions is found by minimizing the norm of transmittance. In a sound field including scattering bodies, an acoustic wave can be refracted on the obstacle boundaries, which enables to control acoustic performance by taking the shape of inclusions as the design variables. In this research, we consider a layered structure which is composed of inclusions arranged periodically in horizontal direction while finite inclusions are distributed in vertical direction. Due to the periodicity of inclusions, a unit cell can be considered to analyze the wave propagation together with proper boundary conditions which are imposed on the left and right edges of the unit cell using the Bloch theorem. The boundary conditions for the lower and the upper boundaries of unit cell are described by impedance matrices, which represent the transmission of waves between the layered structure and the semi-infinite external media. A level set method is employed to describe the topology and the shape of inclusions. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. Through several numerical examples, the applicability of the proposed method is demonstrated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1305-1310
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• 2010

In a practical design process, the method of extracting the design space information of the complex system for verifying, improving, and optimizing the design process by taking into account the design variables and their shape tolerance is very important. Finite element analysis has been successfully implemented and integrated with design of experiment such as D-Optimal array; thus, a response surface model and optimization tools have been obtained, and design variables can be optimized by using the model and these tools. Then, to guarantee the robustness of the design variables, a robust design should be additionally performed by taking into account the statistical variation of the shape tolerance of the optimized design variables. In this study, a new approach based on the use of the response surface model is proposed; in this approach, the standard normal distribution of the shape tolerance is considered. By adopting this approach, it is possible to simultaneously optimize variables and perform a robust design. This approach can serve as a means of efficiently modeling the trade-off among many conflicting goals in the applications of finite element analysis. A case study on the robust optimal design of disc brakes under thermal loadings was carried out to solve multiple objective functions and determine the constraints of the design variables, such as a thermal deformation and weight.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.465-469
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• 2019

In this paper, the design of BLDC (brushless direct current) motors based on torque and back-EMF equations was carried out to assess the application of the motor in concrete vibrators. The air gap flux density of the motor is an important parameter because the length of the motor and the size of the diameter are given. The air gap magnetic flux density was calculated through a simplified magnetic circuit, and basic design of the shape and dimensions of the motor were then determined by carrying out experiments based on torque, back-EMF, and air magnetic flux density equations. After setting the outer and inner diameters, stack lengths, and rated speed of the motor, a detailed design was performed by simulations using the finite element method by designating the diameter and thickness of the motor as the key parameters. The final design to satisfy the target torque and the lowest THD (Total Harmonic Distortion) was carried out along with a simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.48-54
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• 2002

A part definition must not only provide shape information of a nominal part but also contain non-shape information such as tolerances, surface roughness and material specifications. Although machining features are useful for suitable shape information fur process reasoning in CAPP, they need to be integrated with tolerance information for effective process planning. We develop a tolerance modeler that efficiently integrates the machining features with the tolerance information fur feature-based CAPP. It is based on the association of machining features, tolerance features, and tolerances. The tolerance features in this study, where tolerances are assigned, are classified into two types; one type is a face that is a topological entity on a solid model and the other type is a functional geometry that is not referenced to topological entities. The (unctional geometry is represented by using machining features. All the data fur representing the tolerance information are stored completely and unambiguously in an independent tolerance data structure. The developed tolerance modeler is implemented as a module of a comprehensive feature-based CAPP system.

• CDE review
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• v.21 no.1
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• pp.7-12
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• 2015

본 글을 통해 학생들과 함께 수행한 다양한 디지털 디자인 모델을 기반으로 5가지의 디지털 패브리케이션 방식을 적용하여 여러 실제 인테리어패널의 제작 과정 및 그 결과물들을 요약적으로 소개하였다. 해당 과정은 기존의 분리된 설계와 제작 및 시공이 아닌, 설계-제작 통합적인 접근방법을 활용함으로써 학생들로 하여금 디지털 디자인과 패브리케이션의 효과를 극대화 할 수 있음을 체득하도록 하였다. 패브리케이션 기기 및 재료 등의 차이점에 따라 실제 구현된 모델과 원래의 디지털 모델과의 형상적인 차이점은 아직까지 한계점으로 남을 수 있지만, 비정형적으로 생성된 디지털 디자인의 형상이 직접적으로 실현이 가능하다는 점에서 의의가 있다고 할 수 있다. 또한 패러매트릭 모델링 기법이나 실제 제작 경험이 거의 없는 학생들을 대상으로 개별적인 교육이 아닌 설계-제작 통합적인 교육을 실시함으로써 각 요소들이 어떻게 유기적으로 관련되어 디지털 디자인 과정이나 패브리케이션과정에서 상호 보완적으로 중요한지 직접 체득할 수 있도록 하였다는데 의의가 있다. 본 글에서 소개한 재료를 깎는 등의 방식인 "마이너스"의 방식이 아닌 3D프린팅과 같이 재료를 이용해 만들어가는 "플러스"적인 방식 또한 해당 사례에서 수행되었으며 마찬가지로 다양한 특성을 지니고 있으나, 본 글에서는 전자의 방식에 대해 주로 논하였다. 본 글에서 다룬 제작기법뿐만 아니라 3D프린팅 기술의 발전과 보급에 따라 디지털 패브리케이션 역시 다양하게 진보하고 있으며, 팹랩 등을 통한 학교에서의 건축설계 교육도 다양하게 진화하고 있다. 본 사례 및 기타 실험적인 교육과 선도적인 여러 시도를 통해서, 디지털 디자인과 패브리케이션 영역을 확장시켜나가고 해당 기술의 발전에 적극적으로 보조할 수 있는 교육과정을 수립하고 이행하는데 일조 할 수 있기를 희망한다.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.13-19
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• 2018

In this study, the lightweight design of butterfly valve disc component for power plant based on topology optimization was performed. Here, commercial finite element (FE) analysis software was used. The external shape of the basic disc model was not deformed, and the internal element density was removed to make it lightweight. Optimal design was performed each other after the disc plate and two brackets attached on the surface of the disc were separated. Once the optimal shapes were selected, they were assembled to build up the 3-D lightweight valve disc model. After applying pressure to this model, FE analysis was performed to confirm the structural safety.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1021-1024
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• 2010

형상의학은 음양오행설과 수천 년 동안 내려온 임상적 통계에 뿌리를 두고 있는 고유의 전통의학이다. 비록, 과학적 원리는 명확하게 밝혀지지 않았지만 독자적인 체계에 따라 사람 형상을 분류하고 이에 따라 질환을 진단하는 체계를 구성하고 있다. 본 논문에서는 이와 같은 형상의학을 기반으로 코의 형태에 따른 위장질환과의 상관관계를 분석하였다. 이를 위해 얼굴 영상에서 코의 형태를 추출하고 코의 크고 작음, 휨 등에 따라 위장질환과의 관계를 분석하는 실험을 수행하였다. 이를 기반으로 코의 형태와 위장질환과의 객관화, 시각화, 정량화된 출력 지표를 설계하였으며 실험 결과에 대한 유의성을 입증하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.559-567
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• 2012

A level set based topological shape optimization method for nonlinear structure considering hyper-elastic problems is developed. To relieve significant convergence difficulty in topology optimization of nonlinear structure due to inaccurate tangent stiffness which comes from material penalization of whole domain, explicit boundary for exact tangent stiffness is used by taking advantage of level set function for arbitrary boundary shape. For given arbitrary boundary which is represented by level set function, a Delaunay triangulation scheme is used for current structure discretization instead of using implicit fixed grid. The required velocity field in the actual domain to update the level set equation is determined from the descent direction of Lagrangian derived from optimality conditions. The velocity field outside the actual domain is determined through a velocity extension scheme based on the method suggested by Adalsteinsson and Sethian(1999). The topological derivatives are incorporated into the level set based framework to enable to create holes whenever and wherever necessary during the optimization.