• International Journal of CAD/CAM
• /
• 제7권1호
• /
• pp.41-49
• /
• 2007

In density-based topology optimization, 0/1 solutions are sought. Discrete topological problems are often relaxed with continuous design variables so that they can be solved using continuous mathematical programming. Although the relaxed methods are practical, grey areas appear in the optimum topologies. SIMP (Solid Isotropic Microstructures with Penalization) employs penalty schemes to suppress the intermediate densities. SRV (the Sum of the Reciprocal Variables) drives the solution to a 0/1 layout with the SRV constraint. However, both methods cannot effectively remove all the grey areas. SRV has some numerical aspects. In this work, a new scheme SIMP-SRV is proposed by combining SIMP and SRV approaches, where SIMP is employed to generate an intermediate solution to initialize the design variables and SRV is then adopted to produce the final design. The new method turned out to be very effective in conjunction with the method of moving asymptotes (MMA) when using for the stiffness topology optimization of continuum structures for minimum compliance. The numerical examples show that the hybrid technique can effectively remove all grey areas and generate stiffer optimal designs characterized with a sharper boundary in contrast to SIMP and SRV.

• 전자공학회논문지SC
• /
• 제37권2호
• /
• pp.50-59
• /
• 2000

스테레오 영상(stereo image)이란 같은 물체나 장면을 담고있는 서로 다른 시점의 두 영상이며 스테레오 영상에서 깊이 정보를 얻어내는 것을 스테레오 비전(stereo vision)이라 한다. 스테레오 비전에서 가장 중요한 과정은 두 영상에서 서로 일치하는 점을 찾아내는 스테레오 정합(stereo matching)이다. 그러나, 스테레오 정합은 매우 많은 계산을 필요로 하기 때문에 실시간으로 정합하기 어렵다. 본 논문에서는 실시간으로 스테레오 정합을 처리할 수 있는 스테레오 영상 정합 프로세서(stereo image match procesor：SIMP)를 설계하고 구현하였다. 이를 위해 슬라이딩 메모리(sliding memory)와 최소 선택 트리(minimum selection tree)를 제안하였고 파이프라인 구조(pipeline architecture)와 병렬 처리 기법을 이용하였다. SIMP의 입력은 64 그레이 레벨인 두 개의 64×64 스테레오 영상이고 출력은 최대 7의 값을 가지는 변이(disparity)와 12비트의 주소로 이들을 이용하여 64×64 변이도(disparity map)를 구성할 수 있다. SIMP는 약 240 프레임/초의 속도로 스테레오 영상을 처리할 수 있다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.412-417
• /
• 2008

In a traditional topology optimization method, material properties are usually distributed by finite element density and visualized by a gray level image. The distribution method based on element density is adequate for a great mass of 2-D topology optimization problems. However, when it is used for 3-D topology optimization, it is always difficult to obtain a smooth model representation, and easily appears a virtualconnect phenomenon especially in a low-density domain. The 3-D structural topology optimization method has been developed using the node density instead of the element density that is based on SIMP (solid isotropic microstructure with penalization) algorithm. A computer code based on Matlab was written to validate the proposed method. When it was compared to the element density as design variable, this method could get a more uniform density distribution. To show the usefulness of this method, several typical examples of structure topology optimization are presented.

• Structural Engineering and Mechanics
• /
• 제55권6호
• /
• pp.1157-1176
• /
• 2015

This study presents optimizing structural topology patterns using regularization of Heaviside function. The present method needs not filtering process to typical SIMP method. Using the penalty formulation of the SIMP approach, a topology optimization problem is formulated in co-operation, i.e., couple-signals, with design variable values of discrete elements and a regularized Heaviside step function. The regularization of discontinuous material distributions is a key scheme in order to improve the numerical problems of material topology optimization with 0 (void)-1 (solid) solutions. The weak forms of an equilibrium equation are expressed using a coupled regularized Heaviside function to evaluate sensitivity analysis. Numerical results show that the incorporation of the regularized Heaviside function and the SIMP leads to convergent solutions. This method is tested using several examples of a linear elastostatic structure. It demonstrates that improved optimal solutions can be obtained without the additional use of sensitivity filtering to improve the discontinuous 0-1 solutions, which have generally been used in material topology optimization problems.

• Structural Engineering and Mechanics
• /
• 제86권4호
• /
• pp.473-486
• /
• 2023

Nowadays, urban centers are increasingly vertical, making architects and engineers look for more efficient tools to analyze the effects of wind on tall buildings. Topology optimization can be used as an efficient tool for the design of bracing systems. Therefore, this work obtained the wind loads that act in the CAARC building, following the Brazilian standard NBR 6123/1988 and using Computational Fluid Dynamics. Four loading situations were considered, using the SIMP and BESO methods to optimize two-dimensional structures. A comparison between the SIMP and BESO methods is presented, showing the differences in the geometry of the solution found by both methods, the percentage variation in the objective function values and the dimensionless processing time. The solutions obtained through the loads obtained by the Brazilian standard are also compared with the numerical solutions obtained by CFD. The results show that the BESO method presented more rigid structures compared to the SIMP method. The bracing structures obtained with the SIMP method always present similar patterns in the distribution and quantity of bars, in contrast to the BESO method where no characteristic topology pattern was observed. It was concluded that even though the structures obtained by the BESO method presented greater stiffness, the SIMP method was less susceptible to the methodology used for the determination of wind loads. Additionally, it was evident the great potential that the combination topology optimization and computational wind engineering have in the design of bracing systems of high functional and aesthetic standards.

• International Journal of Aeronautical and Space Sciences
• /
• 제14권4호
• /
• pp.324-333
• /
• 2013

The purpose of this paper is to improve the efficiency of multi-objective topology optimization using a genetic algorithm (GA) with bar-system representation. We proposed a new GA using an elite initial population obtained from a Solid Isotropic Material with Penalization (SIMP) using a weighted sum method. SIMP with a weighted sum method is one of the most established methods using sensitivity analysis. Although the implementation of the SIMP method is straightforward and computationally effective, it may be difficult to find a complete Pareto-optimal set in a multi-objective optimization problem. In this study, to build a more convergent and diverse global Pareto-optimal set and reduce the GA computational cost, some individuals, with similar topology to the local optimum solution obtained from the SIMP using the weighted sum method, were introduced for the initial population of the GA. The proposed method was applied to a structural topology optimization example and the results of the proposed method were compared with those of the traditional method using standard random initialization for the initial population of the GA.

• 한국전산구조공학회논문집
• /
• 제20권1호
• /
• pp.9-18
• /
• 2007

본 연구에서는 위상최적화 알고리즘의 수렴성을 개선하기 위해 설계영역에 초기 구멍을 도입하는 방법을 제시하는데, 이것은 경계면에 기초한 최적화 방법의 느린 수렴성을 완화하기 위해, Eschenauer et al.에 의해 고안된 버블 방법의 설계영역 안에 구멍을 도입하는 개념과 연계된다. 버블 방법과 달리, 제안된 방법에서는 최적화 과정동안 구멍의 위치를 정의하는 특성함수를 이용하지 않고, 최적화 초기화 단계에서만 초기 구멍을 도입하는데, 이러한 초기 설계영역 안의 솔리드와 보이드 영역들은 고정되는 것이 아니라 합쳐지거나 쪼개지면서 변화된다. 따라서 위상최적화 알고리즘에서 구멍의 이동에 관련된 복잡한 수치적인 계산 없이 자동적으로 설계변수의 유한변화를 더욱 강화시키기 때문에 목적함수 값의 수렴성을 개선할 수 있다. 본 논문에서는 다양한 치수와 형상의 구멍을 포함하는 초기 설계영역을 가지는 Michell형 보의 위상 최적설계를 밀도분포법으로 불리는 SIMP를 이용하여 수행하였다. 이를 통해 위상최적화의 수렴성을 개선하고 최적위상과 형상에 영향을 미치는 초기 구멍의 효과를 검증하였다.

• 한국전자거래학회지
• /
• 제7권1호
• /
• pp.19-34
• /
• 2002

The main objective of this research is to find out whether there exist any user interface factors that influence service information management professionals(SIMP)'s business activities on the web. The result of this study shows that there exists a significant level of difference between two groups of office Professionals： SIMP and general office management professionals on user interface factors. We analyzed the past and current research results and focused on four major evaluation categories： (1) web design, (2) structure, (3) navigation, and (4) interaction and identified 26 evaluation items in those categories. The study has been initiated by an intuition that there might be a significant difference in sets of user interface factors that influence SIMP and general office professionals. From the list of Best 100 Web Sites the best 30 information-providing web sites and the best 30 service-providing web sites were carefully chosen by a panel of 10 members for each group. To evaluate 60 web sites, another panel was formed by 30 professionals from each group, and they conducted evaluation in their own work settings. Reliability analysis on user interface factors and T-test to find out any influencing factors on SIMP were performed. As a result of this study, we have recognized that clarity, formation, consciseness, economics, and robustness are the most influencing user interface factors for web designers to concern when they develop web sites for SIMP. The study result can be improved by enhancing reliability of choosing target web sites In investigate and panel members. Also, in the future study it is recommended to investigate influencing factors for office professionals in terms of. age, sex, experience, academic background, etc.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
• /
• pp.19-22
• /
• 1987

A program is developed for generations the dynamic equations for robotic manipulators using the symbolic language muSIMP/MATH. The muSIMP/MATH is a LISP-based computer algebra package, devoted to the manipulation of algebraic expressions including number, variables, functions, and matrix. The muSIMP/MATH can operate on IBM-PC compatibles with MS-DOS. The program is developed, on the e formalism. This is program is applicable to the manipulators of any number of degrees of freedom, maximum six degree of freedom in this program. To control robotic manipulators by using dynamic equation is required a symbolic equations. The generated dynamic equation can be applied directly to the robotic manipulators, for the generated dynamic equation is a reduced form of symbolic expression.

• 대한기계학회논문집A
• /
• 제30권2호
• /
• pp.164-170
• /
• 2006

To prevent the numerical instabilities in topology optimization, continuous approximation of material distribution (CAMD) is proposed to the homogenization design method (HDM) and the simple isotropic material with penalization (SIMP) method. The continuous FE approximation of design variables including high order elements is applied to the formulation of SIMP method. Numerical examples are presented to compare the efficiency of CAMD both in HDM and SIMP.