• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.6
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• pp.241-251
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• 2002

The effect of sensor faults in direct torque control(DTC) based induction motor drives is analyzed and a new Instrument fault detection isolation scheme(IFDIS) is proposed. The proposed IFDIS, which operated in real-time, detects and isolates the incipient fault(s) of speed sensor and current sensors that provide the feedback information. The scheme consists of an adaptive gain scheduling observer as a residual generator and a special sequential test logic unit. The observer provides not only the estimate of stator flux, a key variable in DTC system, but also the estimates of stator current and rotor speed that are useful for fault detection. With the test logic, the IFDIS has the functionality of fault isolation that only multiple estimator based IFDIS schemes can have. Simulation results for various type of sensor faults show the detection and isolation performance of the IFDIS and the applicability of this scheme to fault tolerant control system design.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.10
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• pp.337-342
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• 2015

We develop a new parallelization method for Sieve of Eratosthenes algorithm, which enhances both computation speed and energy efficiency. A pipeline scheduling is included for better load balancing after proper workload partitioning. They run on multicore CPUs with hybrid parallel programming model which uses both message passing and multithreading computation. Experimental results performed on both small scale clusters and a PC with a mobile processor show significant improvement in execution time and energy consumptions.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.320-330
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• 2008

This paper presents an improved dynamic programming (IDP) approach to solve the economic power dispatch problem including transmission losses in power systems. A detailed mathematical derivation of recursive dynamic programming approach for the economic power dispatch problem with transmission losses is presented. The transmission losses are augmented with the objective function using price factor. The generalized expression for optimal scheduling of thermal generating units derived in this article can be implemented for the solution of the economic power dispatch problem of a large-scale system. Six-unit, fifteen-unit, and forty-unit sample systems with non-linear characteristics of the generator, such as ramp-rate limits and prohibited operating zones are considered to illustrate the effectiveness of the proposed method. The proposed method results have been compared with the results of genetic algorithm and particle swarm optimization methods reported in the literature. Test results show that the proposed IDP approach can obtain a higher quality solution with better performance.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.643-645
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• 2003

In competitive electricity markets, each GenCo establishes generator maintenance schedule and submits to ISO those. Then, ISO reviews and arranges maintenance schedule of each GenCo to meet the standard for reliability. This paper presents the new optimization model which can apply to competitive electricity markets. The object of this model is to minimize schedules variation of each GenCo and to satisfy system reliability.

• Journal of Korean Society of Transportation
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• v.8 no.2
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• pp.67-75
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• 1990

This paper treats the problem to schedule for trains with how transit priority so as to maximizing the number that can be sent during given time periods without interfering with the fixed schedule for train with high transit priority in a track. We transform the this problem into Time Expanded Network without traverse time through application of Ford and Fulkerson Model and construct the Enumeration Algorithm for solutions using TENET Generator (TENETGEN). Finally, we compare our algorithm with Dinic's Maximal-Flow Algorithm and examine the avaliability of our procedures in personal computer.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.37
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• pp.211-220
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• 1996

We consider the problem of scheduling a maximal amount of additional, low priority transport through a large multiperiod network, given that we may not interfere with an existing schedule for high priority transport. The problem is transformed into the Time-Expanded network(TENET) without traverse time using TENET Generator (TENETGEN). We describe two specialized heuristic algorithms that guarantee the optimal solutions and show the effectiveness of them by comparing quite favorably with Dinic.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.556-557
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• 2008

전력 산업이 경쟁 체제로 변화되면서 고객들의 전기 가격체계가 현물 가격으로 변환되고 있다. 이러한 가격 쳬게에서 전기 가격은 수요와 반응하게 되고 이러한 상호작용을 수요 반응이라 한다. 본 논문에서는 가격의 변화에 따른 수요의 다양한 변화를 가격 민감도, 신뢰도 민감도를 정의하여 설명한다. 이것은 고객의 입장에서는 더 경쟁적인 체계이고 운영자의 입장에서는 더 효율적이고 효과적인 체계이다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.500-501
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• 2008

최근 지구 온난화 가스 배출문제에 관련하여 신재생에너지에 대한 관심이 급증하고 있다. 여러가지 신재생에너지 중의 하나인 태양광 발전은 유력한 에너지 문제의 대안으로 떠오르고 있다. 하지만 이러한 태양광발전의 가장 큰 약점은 날씨에 따라 발전량이 결정된다는 것이다. 따라서 본 논문에서는 태양광 발전의 발전량과 부하량의 각 케이스별로 전력시스템의 발전 스케줄링을 해보려 한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.471-472
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• 2015

This paper proposes a generator maintenance scheduling (GMS) problem with due consideration of various objective functions. The objectives include leveling the reserve rate, maximizing reliability and minimizing production cost. The practicality and effectiveness of the proposed approach are demonstrated in the simulation for a real-size power system model in South Korea.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.6
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• pp.241-246
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• 1984

The power system scheduling process is formulated as an optimization problem with linear inequality constraints. AC Loadflow method is used for the problem solution and line losses are considered. The constraints under consiceration are generator power limits, load schedding 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 applications.