• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1390-1396
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• 2007

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However, it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor. Finally this paper gives the comparison between the simulation results and the experimental results.

• Journal of Drive and Control
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• v.11 no.4
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• pp.32-38
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• 2014

The hydraulic fuse, which responds to the suddenly increased flow on rupture of a line and shuts off the fluid flow, would prevent large spillage of liquid. The quick-acting hydraulic fuse, which is mainly composed of a poppet, a seat, and a spring, must be designed to minimize the leaked flow and to prevent high collision speed between the poppet and seat during fuse operation on a line rupture. The optimal design parameters of a quick-acting hydraulic fuse were searched using the genetic algorithm and the complex method that are kinds of constrained direct search methods. The dynamic behavior of a quick-acting hydraulic fuse was researched using computer simulations that applied the obtained optimal design parameters.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.609-615
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• 1987

The optimal operation of power system is developed by alternately using real power dispatch and reactive power dispatch problem. The real power system scheduling process is formulated as an optimization problem with linear inequality constraints. A.C. loadflow method is used for the problem solution and line losses are considered. The constraints under consideration are generator power limits, load scehdling limits and line capacity limits. In solving the objective function the Dual Relaxation method is adopted. Tests indicate that the method is practical for real time application. The reactive power control problem uses the Dual Simplex Relaxation method as in the real scheduling case. Insted of minimizing the cost of power system, the objective is selected as to determine the highest possible voltage schedule. The constraints under consideration are the voltage limits at each node and the possibilities of supply or absobtion of reactive energy by generator units and the compensation facilities. Tests indicate that the method is practical for real time applications. The overall optimization methods developed in this paper proved to obtained fine results in minimizing object function compared with the method without using voltage control. And the overall voltage profiles were also improved.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.63-71
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• 2014

As power consumption increases, more power utilities are required to satisfy the demand and consequently results in tremendous cost to build the utilities. Another issue in construction of power utilities to meet the peak demand is an inefficiency caused by surplus power during non-peak time. Therefore, most power company considers power demand management with time-based electricity rate policy which applies different rate over time. This paper considers an optimal machine operation problem under the time-based electricity rates. In TOC (Theory of Constraints), the production capacities of all machines are limited to one of the bottleneck machine to minimize the WIP (work in process). In the situation, other machines except the bottleneck are able to stop their operations without any throughput loss of the whole manufacturing line for saving power utility cost. To consider this problem three integer programming models are introduced. The three models include (1) line shutdown, (2) block shutdown, and (3) individual machine shutdown. We demonstrate the effectiveness of the proposed IP models through diverse experiments, by comparing with a TOC-based machine operation planning considered as a current model.

• Journal of Industrial Technology
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• v.37 no.1
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• pp.5-11
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• 2017

The purpose of this research is to propose an efficient loop line operation plan for customer transportation in a new theme park. Based on the expected customer arrivals, customer loading/unloading methods, and scheduled/non-scheduled departure schemes, movement time between stations etc., we have performed indepth analyses and derived the best optimal policy. Our results show that, over all, the operation with separate loading/unloading doors and scheduled departure is preferred to the other options. We then derived the optimal number of trains and cars meeting minimal customer unsatisfaction with low cost for each season.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.63-73
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• 1993

In this paper, fuzzy control algorithm for the speed ratio control of the electro-hydraulic rig type continuously variable transmission(CVT) was proposed and the CVT performance tests were carried out for the optimal operation of the engine simulator. The experimental results for the constant throttle and the acceleration modes showed that the engine can be run on the optimum operating line, representing the power and economy mode, by the fuzzy control of the CVT speed ratio. Comparing the PID control with the fuzzy control, it was found that the fuzzy control showed better performance with the faster rising time and smaller steady state error. The result of this study can be used as basic design materials for developing the transmission control unit of the CVT.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.7
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• pp.318-323
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• 2001

This paper proposes an efficient method of On-Line Economic Load Dispatch(ELD) using Evolutionary Programming(EP) technique at KwangYang steel works. The economic operation of steel works is done by experienced engineer. So far, there is no formulation and algorithm of economic operation of steel works. In this paper, we propose the formulation and On-Line algorithm of economic operation of steel works. The EP technique is the kind of Evolutionary Computation(EC), which has become a candidate for many optimization applications due to its flexibility and efficiency. Based on the EP technique, the proposed algorithm is capable of not only solving the economic problem, but also obtaining the global optimal solutions within reasonable execution time. To validate our proposed approach, the algorithm is demonstrated on many sample systems and compared to actual values of steel works.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.116-118
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• 2000

This paper proposes an efficient method of On-Line Economic Load Dispatch(ELD) using Evolutionary Programming(EP) technique at Kwangyang steel works. The economic operation of steel works is done by experienced engineer. So far, there is no formulation and algorithm of economic operation of steel works. In this paper, we propose the formulation and On-Line algorithm of economic operation of steel works. The EP technique is the kind of Evolutionary Computation(EC) which has become a candidate for many optimization applications due to its flexibility and efficiency. Based on the EP technique, the proposed algorithm is capable of not only solving the economic problem, but also obtaining the global optimal solutions within reasonable execution time. To validate our proposed approach, the algorithm is demonstrated on many sample systems and compared to actual values of steel works.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.97-99
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• 2003

This paper deals with optimal voltage regulation methods of line voltage regulator(SVR : Step Voltage Regulator) in power distribution systems. In order to deliver suitable voltages to as many customers as possible, the optimal sending voltage of SVR should be decided by the effective operation of voltage regulators at the distribution feeders and substations. In this paper, a new voltage regulation method based on the existing method is presented and an optimal coordination method of multiple voltage regulators is extended. The results from a case study show that the proposed methods can be a practical tool for the voltage regulation in distribution systems.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.882-888
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• 2002

In this paper, an algorithm to increase the shift speed is suggested by increasing the line pressure for a metal belt CVT. In order to control the shift speed, an algorithm to calculate the target shift speed is presented from the modified CVT shift dynamics. In applying the shift speed control algorithm, a criterion is proposed to prevent the excessive hydraulic loss due to the increased line pressure. Simulations are performed based on the dynamic models of the hydraulic control valves, powertrain and the vehicle. It is found from the simulation results that performance of the engine operation can be improved by the faster shift speed, which results in the improved fuel economy by 2% compared with that of the conventional electronic control CVT in spite of the increased hydraulic loss due to the increased line pressure.