• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.144-147
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• 1997

Process design of multi-step wire drawing process, conducted by means of finite element analysis and ANN(Artificial Neural Network), has been considered. The investigated problem involves the adequate selection of the drawing die angle and the correspondent reduction rate sequence in the condition of desired initial and final diameter. Combinations of the process parameters which are used in finite element simulation are selected by using orthogonal array. Also the orthogonal array and the results of finite element simulation which are related to the process energy are used as train data of ANN. In this study, it is shown that the new technique using ANN is useful method in application to the wide range of metal forming process.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.2
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• pp.80-86
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• 2001

We design a sliding mode cascade observer to estimate derivatives of the output. In the 1st step of the observer, the output will be estimated, and the 1st order derivative of the output will be estimated via the 2nd step of the observer. Also, nth order derivative of the output will be estimated in the n+1th step of the observer. Exponential convergence of the estimation errors is shown under the bounded initial condition. Numerical examples will be presented to show the validity of the proposed observer.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.1
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• pp.23-30
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• 2022

This study proposed a simplified finite element analysis procedure for designing the nonstructural masonry wall in the out-of-plane direction. The proposed method is a two-step elastic analysis procedure by bilinearizing the behavior of the masonry wall. The first step analysis was conducted with initial stiffness representing the behavior up to the effective-yield point, and the second step analysis was conducted with post-yield stiffness. In addition, the orthotropic material property of the masonry was considered in the FE analysis. The maximum load was estimated as the sum of the maximum loads in the first and second step analyses. The maximum load was converted into the moment coefficients and compared with those from the yield line method applied in Eurocode 6. The moment coefficients calculated through the proposed procedure showed a good match with those from the yield line method with less than 6% differences.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.165-172
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• 1988

An optimal network design method using continuous form of design variables is considered. Modified Hooke-and-Jeeves algorithm has been implemented in order to solve nonlinear progamming problem which is approximately equivalent to the real network design problem (NDP) with system. efficiency criteria(i. e. travel time and costs) and construction cost as objective function. Various forms of construction cost function, locations of initial solution, and dimension of initial step size of link improvement are taken into account to show the validity of this approach. The results obtained are quite promising in terms of the numbers of evaluations in solving NDP, and the speed of convergence. Finally, some techniques in choosing efficient intial solution, initial step size and approximation are given.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.1
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• pp.17-19
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• 2006

This paper presents the design of an electromagnetic system such as jumping ring system, and also considers the characteristics of dynamics for system with initial parameter. For the propose of system analysis, the MATLAB tool is to solve coupled differential equations with inductances and mutual inductance. To apply a real electromagnetic system, this paper implements the jumping ring system using design parameters, and analyzes the jumping ring system with proposal step.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.151-158
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• 2002

Automotive engineers involved in a new car project use various CAD systems that are chosen based on work requirements. For example, engineers in Hyundai Motors are using Pro/Designer and Alias fur the style design, but they use CATIA to design parts and assemblies, ANSYS for FEM analysis, and Pro/Engineer to design engines. Because they use different CAD systems, they have difficulties in collaborative design. Data, which contains errors, is transferred between CAD systems. It is difficult to find out such errors in a large CAD model. An evaluation method for CAD models has been developed in this study. This diagnosis tool analyses a STEP or an IGES file generated from a CAD system, and produces a quantitative error report. The tool has been tested with actual data sets. This paper proposes an algorithm that produces mathematical error values of entities of IGES models that have geometrical data, and entities of STEP models that have topological data, and inspects every part off model. To develop this system, we have used the OpenCASCADE kernel, which is an open source kernel developed by Matra Datavision of France.

• Advances in Computational Design
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• v.1 no.3
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• pp.235-251
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• 2016

We have performed a design optimization of a stiffened panel with curvilinear stiffeners using an artificial neural network (ANN) residual kriging based surrogate modeling approach. The ANN residual kriging based surrogate modeling involves two steps. In the first step, we approximate the objective function using ANN. In the next step we use kriging to model the residue. We optimize the panel in an iterative way. Each iteration involves two steps-shape optimization and size optimization. For both shape and size optimization, we use ANN residual kriging based surrogate model. At each optimization step, we do an initial sampling and fit an ANN residual kriging model for the objective function. Then we keep updating this surrogate model using an adaptive sampling algorithm until the minimum value of the objective function converges. The comparison of the design obtained using our optimization scheme with that obtained using a traditional genetic algorithm (GA) based optimization scheme shows satisfactory agreement. However, with this surrogate model based approach we reach optimum design with less computation effort as compared to the GA based approach which does not use any surrogate model.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.329-330
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• 2021

The calculation of the correct construction value in the construction should be investigated after the quantity is calculated. In order to calculate the quantity requires a lot of cost and time, and the initial accurate quantity calculation is not possible. Therefore, in the planning step in order to successfully complete the project to demonstrate the practicality of the difference between the construction cost by the construction design by presenting a method for calculate the quantity through the estimate with the construction open, floor plan, surface view, section.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.262-271
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• 1998

Recent, more and more steel deck bridges are adopted for the design of long span bridges and the upgrading of existing concrete deck bridges, mainly because of reduced self weight, higher stiffness and efficient erection compared to concrete decks. The main objective of this study is to propose on formulation of the design optimizations to develop an optimal desist program required for optimum desist for orthotropic steel-deck bridges. The objective function of the optimization is formulated as a minimum initial cost design problem. The behavior and design constraints are formulated based on the ASD and LRFD criteria of the Korean Bridge Design Code(1996). The optimum design program developed in this study consists of two steps. In the first step the system optimization of the steel box girder bridges is carried out. And in the second step the program provided the optimum design of the orthotropic steel-deck with close ribs. In the optimal design program the analysis module for the deck optimization is based on the Pelican Esslinger method. The optimizer module of the program utilizes the ADS(Automated Desist Synthesis) routines using the optimization techniques fuor constrained optimization. From the results of real application examples, The cost effectiveness of optimum orthotropic steel-deck bridges designs based on both ASD and LRFD methods is investigated by comparing the results with those of conventional designs, and it may be concluded that the design developed in this study seems efficient and robust for the optimization of orthotropic steel-deck bridges

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.265-271
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• 1992

It is the purpose of this paper to present a dialogical designing method for control system using a rough grasp of the unknown process property. We deal with a single-input single-output feedback control system with a fuzzy controller. The process property is roughly estimated by the step response, and the fuzzy controller is interactively modified according to the operator's requests. The modifying rules mainly derived from computer simulation are useful for almost every process, such as an unstable process and a non-minimum phase process. The fuzzy controller is tuned by taking notice of four characteristics of the step response: (1) rising time, (2) overshoot, (3) amplitude and (4) period of vibration. The tuning position of the controller is fourfold: (1) antecedent gain factor GE or GCE, (2) consequent gain factor GDU, (3) arrangement of the antecedent fuzzy labels and (4) arrangement of the control rules. The rules give an instance to the respective items of the controller in an effective order. The modified fuzzy PI controller realizes a good response of a stable process. However, because the GDU tuning becomes difficult for the unstable process, it is necessary to evaluate the stability of the process from the initial step response. The fuzzy PI controller is applied to the process whose initial step response converges with GDU tuning. The fuzzy PI controller with modified sampling time is applied to the process whose step response converges under the repeated application of the GDU tuning. The fuzzy PD controller is applied to the process whose step response never converges by the GDU tuning.