• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.337-346
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• 2013

A design collaboration system for a plant project is a set of complicated multidisciplinary processes in which a large number of various engineering fields are involved. Each subsystem is related to each other as they depend on information that other subsystems create, which leads to inefficient design iterations. This study presents an optimal design collaboration system for a plant project using Design Structure Matrix (DSM). Data regarding design subsystems, parameters, etc. were obtained by expert surveys and workshops. An automatic analysis program for DSM was developed using Visual Basic Application and Matlab to provide a partitioned DSM. A case study was conducted on a furnace project; consequently, the optimal design collaboration system with five crucial iteration groups was derived.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.750-755
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• 2012

In this study we conduct the optimal spot-weld layout design of vehicle body structure considering dynamic stiffness and side impact. We conduct both linear static analysis and nonlinear analysis with a baseline model to verify the process. 13 design variables will be selected for the effect analysis. Then, topology optimization is conducted to each selected design variable. The design constraints are formulated to improve the dynamic stiffness and side impact performance. Objective function is to set the density of weld component. Optimal spot-weld layout design are compared with the baseline model to show the improvement.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.125-127
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• 2001

Switched reluctance motor (SRM) has some advantages such as low cost, high torque density etc. However SRM has inevitably high torque ripple due to the double salient structure. To apply SRM to industrial field, we have to minimize torque ripple, which is the weak-Point of SRM. This paper presents optimal design process of SRM using numerical method such as 2D finite element method (FEM) and 3D equivalent magnetic circuit network method (EMCNM). The electrical and geometrical design parameters have been adopted as 2D design variables. The overhang structure of rotor has been also adopted as 3D design variable. From this work, we can obtain the optimal design, which minimize the torque ripple and maximize energy conversion loop.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.305-317
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• 2015

Optimal sensor placement (OSP) is an integral component in the design of an effective structural health monitoring (SHM) system. This paper describes the implementation of a novel collaborative-climb monkey algorithm (CMA), which combines the artificial fish swarm algorithm (AFSA) with the monkey algorithm (MA), as a strategy for the optimal placement of a predefined number of sensors. Different from the original MA, the dual-structure coding method is adopted for the representation of design variables. The collaborative-climb process that can make the full use of the monkeys' experiences to guide the movement is proposed and incorporated in the CMA to speed up the search efficiency of the algorithm. The effectiveness of the proposed algorithm is demonstrated by a numerical example with a high-rise structure. The results show that the proposed CMA algorithm can provide a robust design for sensor networks, which exhibits superior convergence characteristics when compared to the original MA using the dual-structure coding method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.63-71
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• 2006

This study presents the effective stiffness-based optimal technique to control Quantitatively lateral drift for shear wall-frame structure system using sensitivity analysis. To this end, the element stiffness matrices are constituted to solve the compatibility problem of displacement degree of freedom between the frame and shear wall. Also, lateral drift constraint to introduce the approximation concept that can preserve the generality of the mathematical programming and can effectively solve the large scaled problems is established. And, the section property relationships for shear wall and frame members are considered in order to reduce the number of design variables and differentiate easily the stiffness matrices. Specifically, constant-shape assumption which is uniformly varying in size during optimal process is applied in frame structure. The thickness or length of shear wall can be changed depending on user's intent. Two types of 20 story shear wall-frame structure system are presented to illustrate the features of the stiffness-based optimal design technique.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.127-136
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• 2006

Metallic sandwich plates with inner dimpled shell subject to 3-point bending have been analyzed and then optimized for minimum weight. Inner dimpled shells can be easily fabricated by press or roll with high precision and bonded with same material skin sheets by resistance welding or adhesive bonding. Metallic sandwich plates with inner dimpled shell structure can be optimally designed for minimum weight subject to prescribed combination of bending and transverse shear loads. Fundamental findings for lightweight design are presented through constrained optimization. Failure responses of sandwich plates are predicted and formulated with an assumption of narrow sandwich beam theory. Failure is attributed to four kinds of mechanisms: face yielding, face buckling, dimple buckling and dimple collapse. Optimized shape of inner dimpled shell structure is a hemispherical shell to minimize weight without failure. It is demonstrated that bending stiffness of sandwich plate is 2 or 3 times larger than solid plates with the same strength. Failure mode boundaries and iso-strength lines dependent upon the geometry and yield strain of the material are plotted with respect to geometric parameters on the failure map. Because optimal parameters of maximum strength for given material weight can be selected from the map, analytic solutions for maximum strength are expressed as a function of only material property and proposed strength. These optimal parameters match well with numerical optimal parameters.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2246-2251
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• 2003

This paper proposes shape design of frame structures for vibration suppression and weight reduction. The $H_{\infty}$ norm of the transfer function from disturbance sources to the output points where vibration should be suppressed, is adopted as the performance index to represent the magnitude of vibration transfer. The design parameters are the node positions of the frame structure, on which constraints are imposed so that the structure achieves given tasks. For computation of Pareto optimal solutions to the two-objective design problem, a number of linear combinations of the $H_{\infty}$ norm and the total weight of the structure are considered and minimized. For minimization of the scalared objective function, a Lagrange function is defined by the objective function and the imposed constraints on the design parameters. The solution for which the Lagrange function satisfies the Karush-Kuhn-Tucker condition, is searched by the sequential quadratic programming (SQP) method. Numerical examples are presented to demonstrate the effectiveness of the proposed design method.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2E
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• pp.51-58
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• 2001

Equations of motion of an engine mount system including foundation flexibility are derived. Forced vibration analysis is carried out for the given engine mount system excited with the unbalanced force and moment. A new optimal design method for the engine mount system is proposed, in which vibration characteristics of the chassis frame structure are considered as design parameters.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1063-1070
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• 2008

The performance of an acoustic transducer is determined by the effects of many design variables, and mostly the influences of these design variables are not linearly independent of each other. To achieve the optimal performance of an acoustic transducer, we must consider the cross-coupled effects of the design variables. In this study, the variation of the performances of underwater acoustic transducer in relation to its structural variables was analyzed. In addition, the new optimal design scheme of an acoustic transducer that could reflect not only individual but also all the cross-coupled effects of multiple structural variables, and could determine the detailed geometry of the transducer with great efficiency and rapidity was developed. The validation of the new optimal design scheme was verified by applying the optimal structure design of a flextensional transducer which are the most common use for high power underwater acoustic transducer. With the finite element analysis(FEA), we analyzed the variation of the resonance frequency, sound pressure, and working depth of a flextensional transducer in relation to its design variables. Through statistical multiple regression analysis of the results, we derived functional forms of the resonance frequency, sound pressure, and working depth in terms of the design variables. By applying the constrained optimization technique, Sequential Quadratic Programming Method of Phenichny and Danilin(SQP-PD), to the derived function, we designed and verified the optimal structure of the Class IV flextensional transducer that could provide the highest sound pressure level and highest working depth at a given operation frequency of 1 kHz.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.661-669
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• 2018

Engineering system problems consist of multi-objective optimisation and the performance analysis is generally time consuming. To optimise the system concerning its performance, many researchers perform the optimisation using an approximation model. The Response Surface Method (RSM) is usually used to predict the system performance in many research fields, but it shows prediction errors for highly nonlinear problems. To create an appropriate metamodel for marine systems, Lee (2015) compares the prediction accuracy of the approximation model, and multi-objective optimal design framework is proposed based on a confirmed approximation model. The proposed framework is composed of three parts: definition of geometry, generation of approximation model, and optimisation. The major objective of this paper is to confirm the applicability/usability of the proposed optimal design framework and evaluate the prediction accuracy based on sensitivity analysis. We have evaluated the proposed framework applicability in derrick structure optimisation considering its structural performance.