• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.7
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• pp.320-326
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• 2003

Slotless Permanent Magnet Linear Synchronous Motor (PMLSM) has good control ability but thrust density is low. So, this paper proposes inserted core type of slotless PMLSM to improve its thrust density. Inserting the core between windings of each phase, detent force is generated by the difference of magnetic resistance in an air gap. To minimize detent force, this paper applies the neural network to inserted core type of slotless PMLSM. The, Magnetic pole ratio, the width of the inserted core and the width of the coil are selected as a design parameter to minimize detent force. In comparison with inserted core type one, thrust ripple greatly decreases by minimizing detent force and also thrust increases in this optimal model.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.239-242
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• 2001

This paper presents a windows program package for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming(EP) and sequential quadratic programming(SQP). The objective functions are the minimization of generation fuel costs and system power losses. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. In OPF considering security, the outages are selected by contingency ranking method. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). The OPF package proposed is applied to 10 machines 39 buses model system.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.194-196
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• 2001

This paper presents a hybrid algorithm for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming (EP) and sequential quadratic programming (SQP). The objective functions are the minimization of generation fuel costs and system power losses. In OPF considering security, the outages are selected by contingency ranking method. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. The method proposed is applied to the modified IEEE 14buses model system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.1-9
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• 2012

Decisions on reliability screening rules and burn-in policies are determined based on the estimated reliability. The variability in a semiconductor manufacturing process does not only causes quality problems but it also makes reliability estimation more complicated. This study investigates the nonuniformity characteristics of integrated circuit reliability according to defect density distribution within a wafer and between wafers then develops optimal burn-in policy based on the estimated reliability. New reliability estimation model based on yield information is developed using a spatial stochastic process. Spatial defect density variation is reflected in the reliability estimation, and the defect densities of each die location are considered as input variables of the burn-in optimization. Reliability screening and optimal burn-in policy subject to the burn-in cost minimization is examined, and numerical experiments are conducted.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.406-413
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• 1999

A compression wave is generated by the high speed train which enters a tunnel, and it propagates along the tunnel. When the compression wave emerges from the exit of the tunnel, it causes an impulsive noise, and the strength of the impulsive noise depends on the pressure gradient of the first compression wave. So it needs to reduce the pressure gradient for the minimization of impulsive noise. The entrance hood is used for the reduction of the pressure gradient. In the present study, the pressure transients were numerically calculated for three shapes of hood, In order to validate the numerical simulation, the pressure and pressure gradient were compared with the experimental data of moving model rig. The calculation results won well agreed with the experimental data, and also showed that the hood had an effect on the pressure gradient of the tunnel inside.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.151-158
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• 1998

This paper presents an optimal decision model for minimizing the life-cycle cost of steel box girder bridges. The point is that it takes into account service life process as a whole, and the life-cycle costs include initial (design, testing, and construction) costs, maintenance costs and expected failure costs. The problem is formulated as that of minimization of expected total life-cycle cost with respect to the design variables. The optimal solution identifies those values of the decision variables that result in minimum expected total cost. The performance constraints in the form of flexural failure and shear failure are those specified in the design code. Based on extensive numerical investigations, it may be positively stated that the optimum design of steel box girder bridges based on life-cycle cost approach proposed in this study provides a lot more rational and economical design, and thus the proposed approach will propose the development of new concepts and design methodologies that may have important implications in the next generation performance-based design codes and standards.

• Journal of Drive and Control
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• v.15 no.3
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• pp.36-42
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• 2018

Agricultural tractors require frequent shifting to improve operation efficiency, and PST (Powershift Transmission) is considered as a suitable transmission. However, due to the inherent characteristics of the PST, shocks arise during shifting, which imparts a negative effect on the operator. Therefore, in order to improve the transmission performance of the tractor PST, researches on various methods including the hydraulic system circuit, the engine input speed control, and the mechanical system of the transmission are steadily being conducted. In this study, in order to reduce the impact of PST on a shift based on SimulationX software, we analyzed the characteristics of the input signal of PCV (Pressure Control Valve) through sensitivity analysis and verified the simulation model through actual vehicle test. Optimization was performed for minimizing the shift shock for some of the parameters of the input signal at constant temperature and RPM conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.630-636
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• 1999

In this paper in optimal modulation controller for position control and anti-sway of container crane systems is designed by a recursive algorithm that determines the state weighting matrix Q of a linear quadratic performance. The optimal modulation controller is based on optimal control. The basic feature of the recursive algorithm is the reduction of the number of iterations as well as minimization of the calculations involved So in order to obtain a mathematical model which rep-resents the equation of motion of the trolley and load Lagrange equation is used. The optimal modulation controller has been verified and simulated to show that it is robust when a load dis-turbance is applied and a reference is changed.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.114-116
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• 2005

This paper deals with an automatic design standard computation based on a rated watt for a synchronous reluctance motor (SynRM). The focus of this paper is mating the design relative to the output rover on the basis of rotor shape of a SynRM in each rated watt using a coupled FEM & sequential unconstrained minimization technique (SUMT). The coupled finite elements analysis (FEA) & Preisach model have been used to evaluate nonlinear solutions. The proposed procedure allows to define the rotor geometric dimensions according to the rotor diameter and rated watt starting from an existing motor or a preliminary design.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.8
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• pp.463-470
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• 2003

This paper proposes an expert system, which is able to determine the problem-solving strategy for diversity events occurred on the distribution system. The events include events related to the fault, scheduled outage and optimal operating task such as feeder line fault, line scheduled outage, line overload, system load balancing, system loss minimization, main transformer fault, main transformer scheduled outage, main transformer overload, main transformer protection control. The expert system enhances the reliability of software designed by the integrated concept for the diversity events. The expert system is implemented in C language. And the effectiveness and accuracy for the expert system is verified by simulating the event cases for typical distribution model.