• Structural Engineering and Mechanics
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• 제71권3호
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• pp.283-290
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• 2019

In global competition manufacturing companies have to produce modern, new constructions from advanced materials in order to increase competitiveness. The aim of my research was to develop a new composite cellular plate structure, which can be primarily used for structural elements of road, rail, water and air transport vehicles (e.g. vehicle bodies, ship floors). The new structure is novel and innovative, because all materials of the components of the newly developed structure are composites (laminated Carbon Fiber Reinforced Plastic (CFRP) deck plates with pultruded Glass Fiber Reinforced Plastic (GFRP) stiffeners), furthermore combines the characteristics of sandwich and cellular plate structures. The material of the structure is much more advantageous than traditional steel materials, due mainly to its low density, resulting in weight savings, causing lower fuel consumption and less environmental damage. In the study the optimal construction of a given geometry of a structural element of a road truck trailer body was defined by single- and multi-objective optimization (minimal cost and weight). During the single-objective optimization the Flexible Tolerance Optimization method, while during the multi-objective optimization the Particle Swarm Optimization method were used. Seven design constraints were considered: maximum deflection of the structure, buckling of the composite plates, buckling of the stiffeners, stress in the composite plates, stress in the stiffeners, eigenfrequency of the structure, size constraint for design variables. It was confirmed that the developed structure can be used principally as structural elements of transport vehicles and unit load devices (containers) and can be applied also in building construction.

• Structural Engineering and Mechanics
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• 제71권4호
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• pp.417-432
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• 2019

Seismic performance analysis of steel-brace reinforced concrete (RC) frame using topology optimization in highly seismic region was discussed in this research. Topology optimization based on truss-like material model was used, which was to minimum volume in full-stress method. Optimized bracing systems of low-rise, mid-rise and high-rise RC frames were established, and optimized bracing systems of substructure were also gained under different constraint conditions. Thereafter, different structure models based on optimized bracing systems were proposed and applied. Last, structural strength, structural stiffness, structural ductility, collapse resistant capacity, collapse probability and demolition probability were studied. Moreover, the brace buckling was discussed. The results show that bracing system of RC frame could be derived using topology optimization, and bracing system based on truss-like model could help to resolve numerical instabilities. Bracing system of topology optimization was more effective to enhance structural stiffness and strength, especially in mid-rise and high-rise frames. Moreover, bracing system of topology optimization contributes to increase collapse resistant capacity, as well as reduces collapse probability and accumulated demolition probability. However, brace buckling might weaken beneficial effects.

• 한국경영과학회지
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• 제22권3호
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• pp.1-9
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• 1997

We present an extension of the well-known generalized upper bound (GUB) constraint and consider a linear knapsack problem with both the extended GUB constraints and the simple upper bound (SUB) constraints. An efficient algorithm of order O($n^2log n$) is developed by exploiting structural properties and applying binary search to ordered solution sets, where n is the total number of variables. A numerical example is presented.

• 한국생산제조학회지
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• 제5권4호
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• pp.74-81
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• 1996

This paper is to estimate sizing design sensitivity of linear and nonlinear vehicle frame structure using structural ananlysis result from ANSYS. Using design sensitivity results, optimal design of plane vehicle frame structure with buckling constraint is carried out the gradient projection method. Optimal design results are compares gradient projection method resrult with SUMT result.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.200-207
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• 2003

The seismic behaviors of steel moment connections are investigated based on the numerical analysis of the connections with US and Japanese typical details. The rupture index, representing the fracture potential, is used to evaluate the ductility of the connections at the critical location. The results show that the presence of a slab increases the beam strength, imposes constraint near the beam top flange, and consequently, induces concentrated deformation near the beam access hall, which reduces the ductility of the connection. The total deformation capacity of the connection depends not only on a beam but also on a column and panel zone.

• 대한기계학회논문집A
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• 제20권3호
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• pp.872-881
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• 1996

The concept of homology design has been devised for the application to large telescope structure by S.v.Hoerner. It is defined that the deformation of a structure shall be called homologous, if a given geometrical relation holds, for a given number of structural points, before, during, and after the deformation. Recently, the need of homology design in the structural design has been increase due to the required precision in the structure. Some researchers have utilized the theory on the structural design with finite element method in the late 1980s In the present investigation, a simple method using geometrical equality constraints is suggested to gain homologous deformation. The previous method is improved in that the decomposition of FEM eqation, which is very expensive, is not necessary. The basic formulations of the homology design with the optimization concept are described and several practical examples are solved to verify the usefulness and validity. Especially, a back-up structure of a satellite antenna is designed by the suggested method. The results are compared with those of existing researches.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.131-134
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• 2018

구조방정식 모델링은 경로분석 및 확인적 요인분석을 동시에 수행해 주는 통계적 절차를 따르고 있다. 오늘날이 통계적 절차는 사회과학 분야의 연구자에게 필수적인 도구이다. 구조방정식 모델링 분석을 해주는 대표적인 도구로는 (AMOS, LISREL and PLS)가 있다. AMOS는 초보자가 사용할 수 있도록 편리한 그래픽 사용자 인터페이스를 제공해 주고 있다. PLS는 그래픽 사용자 인터페이스뿐만 아니라 정규분포에 대한 제약조건도 없다는 장점을 가지고 있다. 또한 사회과학 분야에서 가장 많이 사용하는 3가지 도구(Applications)를 비교분석 하였다. 이러한 결과를 바탕으로 연구의 한계와 시사점을 제시하고자 한다.

• Earthquakes and Structures
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• 제7권6호
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• pp.1119-1139
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• 2014

A damage-based seismic design procedure for steel frame structures is formulated as an optimization problem, in which minimization of the initial construction cost is treated as the objective of the problem. The performance constraint of the design procedure is to achieve "repairable" damage state for earthquake demands that are less severe than the design ground motions. The Park-Ang damage index is selected as the seismic damage measure for the quantification of structural damage. The charged system search (CSS) algorithm is employed as the optimization algorithm to search the optimum solutions. To improve the time efficiency of the solution algorithm, two simplifying strategies are adopted: first, SDOF idealization of multi-story building structures capable of estimating the actual seismic response in a very short time; second, fitness approximation decreasing the number of fitness function evaluations. The results from a numerical application of the proposed framework for designing a twelve-story 3D steel frame structure demonstrate its efficiency in solving the present optimization problem.

• 한국소음진동공학회논문집
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• 제16권2호
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• pp.115-123
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• 2006

A feasibility of using the topology optimization method for structural damage identification is investigated for the first time. The frequency response functions (FRFs) are assumed to be constructed by the finite element models of damaged and undamaged structures. In addition to commonly used resonances, antiresonances are employed as the damage identifying modal parameters. For the topology optimization formulation, the modal parameters of the undamaged structure are made to approach those of the damaged structure by means of the constraint equations, while the objective function is an explicit penalty function requiring clear black-and-white images. The developed formulation is especially suitable for damage identification problems dealing with many modal parameters. Although relatively simple numerical problems were considered in this investigation, the possibility of using the topology optimization method for structural damage identification is suggested through this research.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.142-156
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• 2015

A new method for ship Inner Shell optimization, which is called Parametric Inner Shell Optimization Method (PISOM), is presented in this paper in order to improve both hull performance and design efficiency of transport ship. The foundation of PISOM is the parametric Inner Shell Plate (ISP) model, which is a fully-associative model driven by dimensions. A method to create parametric ISP model is proposed, including geometric primitives, geometric constraints, geometric constraint solving etc. The standard optimization procedure of ship ISP optimization based on parametric ISP model is put forward, and an efficient optimization approach for typical transport ship is developed based on this procedure. This approach takes the section area of ISP and the other dominant parameters as variables, while all the design requirements such as propeller immersion, fore bottom wave slap, bridge visibility, longitudinal strength etc, are made constraints. The optimization objective is maximum volume of cargo oil tanker/cargo hold, and the genetic algorithm is used to solve this optimization model. This method is applied to the optimization of a product oil tanker and a bulk carrier, and it is proved to be effective, highly efficient, and engineering practical.