• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.17 no.4
• /
• pp.389-403
• /
• 2004

This study presents the structural model modification based on the modal data such as natural frequencies and mode shapes. Preliminary structural model can be obtained using design drawings and field measurement, and therefore the deteriorated stiffness of a structure and the effect of the boundary conditions are difficult to be evaluated in preliminary analysis model, and the preliminary model can be modified using structural response data including static and/or dynamic characteristics. In this study, the structural model is modified based on the structural modal data using genetic algorithm. Modal testing were carried out for Imjin River Bridge and Hangjoo Bridge, the modal properties were estimated using modal identification techniques, and finally the structural models were updated using genetic algorithm. The modified structural model could give us more reliable structural analysis results and therefore those can be used for structural performance evaluation such as load carrying capacity and seismic capacity.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.5
• /
• pp.549-558
• /
• 2012

This study identifies the damage detection of truss structures by using genetic algorithm(GA) from changed elements properties. To model the damaged truss structures, the modulus of elasticity of some specific elements is reduced. The analysis of truss structures is performed with static analysis by applying uniform load, and the location and extent of structural damage is detected by comparing the stain of each element of healthy truss structures with damaged truss structures using genetic algorithm. In this study, some numerical examples are presented to detect the location and extent of damage using genetic algorithm.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.1
• /
• pp.33-42
• /
• 2010

Patterning with a geodesic line is essential for economical or efficient usage of membrane materialsin fabric tension membrane structural engineering and analysis. The numerical algorithm to determine the geodesic line for membrane structures is generally classified into two. The first algorithm finds a non-linear shape using a fictitious geodesic element with an initial pre-stress, and the other algorithm is the geodesic line cutting or searching algorithm for arbitrarily curved 3D surface shapes. These two algorithms are still being used only for the three-node plane stress membrane element, and not for the four-node element. The lack of a numerical algorithm for geodesic lines with four-node membrane elements is the main reason for the infrequent use of the four-node membrane element in membrane structural engineering and design. In this paper, a modified numerical algorithm is proposed for the generation of a geodesic line that can be applied to three- or four-node elements at the same time. The explicit non-linear static Dynamic Relaxation Method (DRM) was applied to the non-linear geodesic shape-finding analysis by introducing the fictitiously tensioned 'strings' along the desired seams with the three- or four-node membrane element. The proposed algorithm was used for the numerical example for the non-linear geodesic shape-finding and patterning analysis to demonstrate the accuracy and efficiency, and thus, the potential, of the algorithm. The proposed geodesic shape-finding algorithm may improve the applicability of the four-node membrane element for membrane structural engineering and design analysis simultaneously in terms of the shape-finding analysis, the stress analysis, and the patterning analysis.

• Computational Structural Engineering
• /
• v.11 no.4
• /
• pp.321-330
• /
• 1998

막구조의 초기형상을 결정하기 위하여 막요소의 기하학적 비선형을 고려한 평형방정식을 유도하고, 등장력곡면(equally stressed surface)을 결정하기 위한 알고리즘을 정식화한다. 막구조는 대변형에 의한 기하학적 비선형성을 포함하고, 막구조의 특성상 초기장력에 의한 초기변형을 고려해야 하므로, 본 논문에서는 막구조와 같은 인장구조물의 비선형 수치해석을 수행하기 위한 해석기법으로써, 동적이완법(Dynamic Relaxation Method)에 대한 해석알고리즘을 적용하고, 이 방법에 의해 수행한 해석결과를 검토함으로써 막구조 해석에 적용 가능한 수치해석기법을 제시하고, 수치해석에 대한 예를 통해 본 해석법의 타당성을 검증한다.

• Aerospace Engineering and Technology
• /
• v.12 no.2
• /
• pp.24-29
• /
• 2013

A spacecraft radiator is a thermal control method to eject internally dissipated heat into the space generated from operation of unit boxes. The efficiency of thermal design may be improved by optimizing radiator design. In this paper, the optimization approach method of node-based radiator design was suggested which is to combine numerical thermal analysis with optimization algorithm. This method has meaning that it can be used practically to implement the spacecraft radiator design regardless of thermal analysis and optimization algorithm software and maintain the same basic concept of an ordinary radiator design approach based on node division of a thermal model. The overall analysis framework with thermal analysis and optimization algorithm would be presented.

• Proceedings of the KIEE Conference
• /
• 1997.07a
• /
• pp.3-5
• /
• 1997

지구 물리학이나 의공학 분야등에서 이용되왔던 전기비저항 탐사법은 관심 영역에 전류 입력을 가한 후, 그에 대한 전압 응답을 측정하여 관심 영역 내의 전기비저항 분포를 규명하는 방법으로서 역해석 문제의 범주에 포함된다. 따라서 일반적인 역해석 문제가 지니고 있는 해의 존재성, 유일성, 그리고 측정 데이터에 대한 해의 연속적 의존성이라는 기본적 문제들을 가지게된다. 이러한 역해석 문제의 해결에는 정확한 정해석 풀이법과 효율적인 역해석 방법이 요구되어진다. 본 논문에서는 정해석 방법으로 유한요소법을, 역해석 방법으로는 전체 최적점을 발견할 가능성이 높은 유전 알고리즘을 최적화 방법으로 사용하였다. 기존의 역해석 문제의 해결책으로 제시되어왔던 기울기 방법에 기반한 결정론적 최적화 알고리즘들이 지니고 있는 국소해로의 수렴, 즉 단순한 전기비저항 분포의 불연속성 확인이라는 한정된 정보의 획득을 넘어서 실제 전기비저항 분포와 가장 가까운 분포는 전체 최적점 근처에서 발견될 수 있음을 보이고자 한다. 이러한 전기비저항 분포의 역해석적인 규명을 간단한 2차원 수치해석문제를 풀어보므로서 확인해본다.

• Journal of Fisheries and Marine Sciences Education
• /
• v.6 no.2
• /
• pp.117-129
• /
• 1994

본 논문에서는 접촉하는 두 물체의 동적접촉문제를 해석하기위한 음해법과 양해법을 합성한 새로운 하이브리드 해석방법을 제안하였다. 그리고 양해법의 결과를 기준으로 하여 그 계산정도를 비교하고 제안한 방법의 정도와 효율의 유효성을 조사하였다. 얻어진 결과를 요약하면 아래와 같다. 1) 마찰을 고려한 음해법과 양해법의 정식화를 통하여 접촉상태에서 분리가 일어날때 까지를 표현할 수 있는 새로운 알고리즘을 제시하였다. 2) 본 방법은 종래의 음해법에 비해 계산시간이 짧고 계산정도는 거의 비슷한 결과를 보였다. 3) 하이브리드법은 알고리즘의 변경이 간단하고, 동적접촉문제의 해석을 위한 실용적인 면에 큰 장점을 가지고 있다.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.3
• /
• pp.5-11
• /
• 2008

This paper pertains to the incorporation of a genetic algorithm methodology for determining the critical slip surface and the corresponding factor of safety of soil slopes using inclined slice method. The analysis is formulated as a constrained optimization problem to solve the nonlinear equilibrium equations and finding the factor of safety and the critical slip surface. The sensitivity of GA optimization method is presented in terms of development of failure surface. Example problem is presented to demonstrate the efficiencies of the genetic algorithm approach. The results obtained by this method are compared with other traditional optimization technique.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.6
• /
• pp.117-127
• /
• 2002

A deterministic approach of slope stability, which is generally corresponding to the model of a simple non-linear function for slopes, is problematic in that it does not account the versatile characteristics of ground layers in an effective way. To resolve this problem, this study proposes a new way of analyzing slope stability, so-called “genetic algorithm method, ” so as to reflect some particular conditions pertaining to the grounds under concern. Similarities and differences in slope stability that may exist between homogeneous and multiple ground layers are examined in a competitive manner, Overall, though similarities deemed a little bit salient, the algorithm method turned out to be very applicable to estimating the validity of slope stability. Furthermore, an additional effort to consider long-standing sequential and dynamic changes in both the amount of rainfall and the underground water level is made in order to improve the results.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.4
• /
• pp.287-294
• /
• 2007

A static aeroelastic analysis for supersonic aircraft wing equipped with external store under the wing lower surface is performed using computational fluid dynamics (CFD) and computational structural technology(CST) coupling methodology. Two mapping algorithms, which are the pressure mapping algorithm and the displacement mapping algorithm, are used for CFD/CST coupling. A three-dimensional unstructured Euler code and finite element analysis program are used to calculate the flow properties and the structural displacements, respectively. The coupling procedure is repeated in an iterative manner until a specified convergence criterion is satisfied. Static aeroelastic analysis for a typical supersonic flight wing is performed and final converged wing configuration is obtained after several iterations.