• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.335-347
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• 2003

본 논문에서는 설계 하중에 지배되는 구조물에 있어서, 입력 파라미터들의 불확실성을 표준편차와 패턴의 변동, 두 차원에서 접근, 처리할 수 있는 방안을 제시하기 위해서 구조물에 입력으로 작용하는 하중 패턴의 결정과 구조물의 형상의 진화를 동시에 고려할 수 있는 Co-Evolutionary Structural Design framework라 명명한 새로운 구조 설계 방식을 개발하였다. 공학자의 직관과 경험 의존적인 하중을 대상으로 최적화된 구조물은, 성능에 완벽한 안전을 보장해 줄 수 없으며, 이에 관한 문제를 해결하기 위해서 주어진 상황 속에서 다양한 하중이 작용하더라도 안전할 수 있는 구조물의 설계 방식에 관해서 설명한다. 본 프레임워크는 연성을 가지는 두 Disciplinary Modules, 즉 구조 형상설계와 하중설계로 이루어지며 하중에 관한 DB로 연결되어 순차적인 MDO 설계과정을 거치게 된다. 두 Discipline은 설계과정을 거치면서 상호 견제의 틀 속에서 진화하며 기존 방식과 달리 극한 하중 패턴을 스스로 찾아서 설계 반영하는 특징을 가진다. 본 접근 방식의 유용성을 평가하기 위해서 10-bar truss 구조물과 Jacket-Type 구조물로 테스트해 보았다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.38-42
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• 2007

In this study, cruise missile configuration is optimal designed by using multidisciplinary analysis. Aerodynamic, weight, performance and mission analysis modules are developed by FORTRAN and integrated with framework. Darwin algorithm, a global optimization tool, is used for optimization. In the result of optimal design, gross weight of designed configuration is reduced about 17% than baseline configuration while satisfying design constraint conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.535-540
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• 2019

The coupling between different models for MDO (Multi-disciplinary Optimization) greatly increases the complexity of the computational framework, while at the same time increasing CPU time and memory usage. To overcome these difficulties, POD (Proper Orthogonal Decomposition) and RBF (Radial Basis Function) are used to solve the optimization problem of determining the thickness of composites and sandwich cores when composite sandwich structures are used as aircraft wing skin materials. POD and RBF are used to construct surrogate models for the wing shape and the load data. Optimization is performed using the objective function and constraint function values which are obtained from the surrogate models.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.1-9
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• 2022

In this study, for development of the MDO (Multi Disciplinary Optimization) framework, the flight dynamic characteristic parameters of the ChangGong-91, a light aircraft, were extracted by an analytical method based on various semi-empirical methods, and the flight test method was compared and evaluated. The semi-empirical analysis methods for comparative subjects were the Perkins method, McCormick method, and Smetana method. The major stability/control derivatives and dynamic factors were calculated, using each method. As the comparison criteria, the flight test derivative estimates and dynamic factors were processed, using the output error method. Additionally, the flight characteristics of the light aircraft were analyzed and evaluated according to the provisions of the Korean Airworthiness Standard (KAS) of the Ministry of Land, Infrastructure and Transport, and MIL-F-8785C for the U.S. military.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.12-19
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• 2004

An aerodynamic design optimization system for three-dimensional wing was developed as a part of the future MDO framework. The present design optimization system includes four modules such as geometry design, grid generation, flow solver and optimizer. All modules were based on commercial softwares and programmed to have automated execution capability in batch mode utilizing built-in script and journaling. The integration of all modules into the system was accomplished through programming using Visual Basic language. The distributed computational environment based on network communication was established to save computational time especially for time-consuming aerodynamic analyses. The distributed aerodynamic computations were performed in conjunction with the global optimization algorithm of response surface method, instead of using usual parallel computation based on domain decomposition. The application of the design system in the drag minimization problem demonstrated considerably enhanced efficiency of the design process while the final design showed reasonable results of reduced drag.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.18-25
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• 2005

Existing methods have performed the reliability analysis using nonlinear optimization techniques. This is mainly due to the fact that they directly apply Multidisciplinary Design Optimization(MDO) frameworks to the reliability analysis formulation. Accordingly, the reliability analysis and the Multidisciplinary Analysis(MDA) are tightly coupled in a single optimizer, which hampers utilizing the recursive and function-approximation based reliability analysis methods such as the Advanced First Order Reliability Method(AFORM). In order to utilize the efficient reliability analysis method under multidisciplinary analysis systems, we propose a new strategy named Sequential Approach on Reliability Analysis under Multidisciplinary analysis systems(SARAM). In this approach, the reliability analysis and the MDA are decomposed and arranged in a sequential manner, making a recursive loop. The efficiency of the SARAM method was verified using three illustrative examples taken from the literatures. Compared with existing methods, it showed the least number of subsystem analyses over other methods while maintaining accuracy.