• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.972-974
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• 1993

This paper presents a new method to automatically design fuzzy logic controller(FLC). The main problems of designing FLC are how to optimally and automatically select the control rules and the parameters of membership function (MF). Cell state space algorithms (CSS), differential competitive learning (DCL) and multialyer neural network are combined in this paper to solve the problems. When the dynamical model of a control process is known. CSS can be used to generate a group of optimal input output pairs(X, Y) used by a controller. The(X, Y) then can be used to determine the FLC rules by DCL and to determine the optimal parameters of MF by DCL and to determine the optimal parameters of MF by multilayer neural network trained by BP algorithm.

• Journal of Power System Engineering
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• v.3 no.4
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• pp.63-68
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• 1999

The determination of the optimal machining parameters in metal cutting, such as cutting speed, feed rate, and depth of cut, is an important aspect in an economic manufacturing process. The main objective in general is either to minimize the production cost or to maximize the production rate. Also there are constraints on all the machining operations which put restrictions on the choice of the machining parameters. In this paper as an objective function the production cost is considered with two constraints, surface finish and cutting power. Genetic Algorithm is applied to determine the optimum machining parameters, and the effectiveness of the applied algorithm is demonstrated by means of an example, turning operation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.1-8
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• 2004

Various controllable parameters of an experiment have influence on grinding process. In order to get good products with a high quality, these parameters should be considered whether each parameter has relations to the quality. This paper describes the use of the design of experiments to minimize geometric error in surface grinding. Controllable parameters for the design of experiments were selected as spindle speed, table speed, depth of cut and grain size. From the experimental results, a degree of influence between these parameters and the geometric error was evaluated. An optimal set of grinding conditions was obtained by means of analysis of variance(ANOVA).

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.88-95
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• 2008

With society focusing more and more on environmental issues, the recycling of materials of all types has become an important concern. In this paper, optimization method is developed for reducing cost and improving quality in mill scale recycling. An experimental investigation into the process parameter effects is presented to determine the optimum configuration of parameters for performance, quality and cost. Taguchi's optimization approach was used to obtain the optimal parameters. The significant parameters were identified and their effects on mill scale recycling were studied. As a results, a confirmation experiment with the optimal levels of process parameters was carried out in order to demonstrate the effectiveness of the Taguchi method.

• IE interfaces
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• v.11 no.1
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• pp.145-153
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• 1998

In this paper, two parts of neural networks were proposed for determination of optimal EDM parameters. One is pattern recognition neural network that can be selecting expert neural network suitable to the EDM mode. The other is expert neural network that can be determining optimal EDM parameters such as pulse on time and pulse off time. Prior to determination of EDM parameters, Peak current, which is related to the EDM area closely, determined base on EDM area that is calculated from CAD data, firstly. Then, the other EDM parameters determined by the expert neural network that is selected to the EDM mode.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.223-227
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• 2002

Wind tunnel test or CFD is used for predicting aerodynamic drag coefficient in domestic motor companies. But, wind tunnel test requires much cost and time, and CFD has a relatively large error. In this study a predicting program of the aerodynamic drag coefficient based on empirical techniques was developed. Also GRG method was added to the program in order to decide optimal values of some parameters. The program was applied to 24 cars and the aerodynamic drag coefficients were predicted with 4.82% average error. Optimization was also accomplished to 6 cars. Some parameters to be modified were determined (1) to reduce the afterbody drag coefficient to the value established by a designer and (2) to preserve the same drag coefficient as the original automotive when some parameters have to be changed in the viewpoint of design. It was verified that the developed program can predict the aerodynamic drag coefficient appropriately and determine optimal values of some parameters.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.85-101
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• 2020

The optimal parameters for the fluid-structure interaction analysis using the Smoothed Particle Hydrodynamics (SPH) for fluids and finite elements for structures, respectively, are explored, and the effectiveness of the simulations with those parameters is validated by solving several open surface fluid problems. For the optimization of the Equation of State (EOS) and the simulation parameters such as the time step, initial particle spacing, and smoothing length factor, a dam-break problem and deflection of an elastic plate is selected, and the least squares analysis is performed on the simulation results. With the optimal values of the pivotal parameters, the accuracy of the simulation is validated by calculating the exerted force on a moving solid column in the open surface fluid. Overall, the SPH-FEM coupled simulation is very effective to calculate the fluid-structure interaction. However, the relevant parameters should be carefully selected to obtain accurate results.

• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.123-132
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• 2017

A smart tuned mass damper (TMD) was developed to provide better control performance than a passive TMD for reduction of earthquake induced-responses. Because a passive TMD was developed decades ago, optimal design methods for structural parameters of a TMD, such as damping constant and stiffness, have been developed already. However, studies of optimal design method for structural parameters of a smart TMD were little performed to date. Therefore, parameter studies of structural properties of a smart TMD were conducted in this paper to develop optimal design method of a smart TMD under seismic excitation. A retractable-roof spatial structure was used as an example structure. Because dynamic characteristics of a retractable-roof spatial structure is changed based on opened or closed roof condition, control performance of smart TMD under off-tuning was investigated. Because mass ratio of TMD and smart TMD mainly affect control performance, variation of control performance due to mass ratio was investigated. Parameter studies of structural properties of a smart TMD was performed to find optimal damping constant and stiffness and it was compared with the results of optimal passive TMD design method. The design process developed in this study is expected to be used for preliminary design of a smart TMD for a retractable-roof spatial structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1066-1073
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• 2014

This paper presents a new design method of optimal control of system which are changed the system parameters. The method used for this purpose are the Lagrange interpolation method and Pole's Moving range method. We selects a system within the scope of the changing the system parameters. Using pole's moving range we calculated the state weighting matrix of optimal control. The optimal controller is designed by Lagrange interpolation method of the state weighting matrix. We are compared with a traditional optimal controller and proposed method by simulation. The simulation showed that the proposed method is better control performance than traditional method of optimal controller.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.50-58
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• 2007

In this paper, the optimum position of optical phase conjugator (OPC) and the optimal dispersion coefficients of fiber sections in $16{\times}40$ Gbps WDM system with non zero - dispersion shifted fiber (NZ-DSF) of 1,000 km are induced, in order to expand the availability of mid-span spectral inversion (MSSI) technique in long-haul multi-channel transmission systems. It is confirmed that the compensation degrees of overall WDM channels are more improved by applying the induced optimal parameters into WDM system than those in WDM system with the conventional MSSI. So it is expected that the proposed optimal parameters should alternate with the forming method of the symmetrical distributions of optical power and local dispersion with respect to OPC, which generate a serious problem in the applying OPC into multi-channels WDM system if it is not formed. It will be possible to realize the flexible system design by applying the methods proposed in this paper into the real WDM system with OPC.