• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.668-673
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• 2003

Line Capacity is a criteria for transport capacity and is used to evaluate railroad investment alternatives or to decide train frequency when establish transportation plan. There are two methodologies to increase transport capacity of railway. One is to invest railroad equipment or vehicles, and the other is to improve operation efficiency through optimization. Such all efforts are intended to increase transport capacity by improving line capacity. So far, this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that changes dynamically according to operational conditions, so there is a need of new line capacity estimation system. In this paper, we present a new estimation method of line capacity based on the probability simulation, and apply to normal railline section and special structured railine section.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.272-279
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• 2003

There are two methodologies to increase transport capacity of railway. One is to invest railroad equipment or vehicles, and the other is to improve operation efficiency through optimization. All of these is intended to increase transport capacity by improving the line capacity, So far, we treat the line capacity as the criteria for evaluating investment alternatives or for restricting train frequencies, and this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that changes dynamically according to operational conditions, so there is a need of new line capacity estimation system. Korea Railroad Research Institute(KRRI) proposed a new line capacity estimation system based on the probability simulation method. In this research. we perform analysis of line capacity for the railway improvement alternatives, and to represent the results.

• Water for future
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• v.18 no.4
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• pp.295-299
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• 1985

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.491-497
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• 2018

Most of the applications for distribution system operation highly rely on the voltage and current managements from the field devices. Voltage from the remote controlled switch contains unacceptably large measurement error due to the nonlinear characteristics of the bushing potential transformer. This paper proposes a new voltage magnitude estimation method by calculating voltage drop using current measurement, line impedance and loads deployment data. Contract demand power and pole transformer capacity managed by NDIS are used as a key element to improve accuracy of the proposed method. Various case studies using Matlab simulation have been performed to verify feasibility of the propose voltage estimation method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.1047-1049
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• 2009

This paper presents an intelligent electronic device(IED) platform which is based on a new frequency estimation algorithm. The IED platform features not only the accurate estimation of frequency but also the fast network-based transmisstion of fault data and waveforms. The simulation results show that the proposed frequency estimation algorithm improves convergence speed, and has lower frequency estimation error compared with those of conventional algorithms. The network-based IED is designed to ensure transmission latency being less than 1.0% of sampling interval.

• Journal of Power Electronics
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• v.14 no.5
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• pp.1000-1007
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• 2014

This paper proposes an on-line rotor time constant estimation strategy for indirect field oriented induction machines. The performance of the indirect field oriented control is dependent especially on the rotor time constant whose value varies according to the temperature. The proposed method calculates the difference between the nominal rotor time constant and the real value from the d- and q-axis integration terms of a proportional integral (PI) current regulator and the demanded voltages of the induction machine to regulate the current in the steady state. Because the proposed strategy has a simple structure and is available in wide speed and torque ranges, the proposed method can be easily used in the industrial field. The effectiveness of proposed strategy is verified with simulations and a 7.5kW experimental setup.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.291-296
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• 2015

Transmission line is exposed to a large area, and then faults are likely to occur than the other component of power system. When a fault occurs on a transmission line, fault locator helps fast recovery of power supply on power system. This paper deals with the design of a digital fault locator for improvement accuracy of the fault distance estimation and a fault occurrence position for transmission line. The algorithm of a fault locator uses a DC offset removal filter and DFT filter. The algorithm utilizes a fault data of GPS time synchronized. The computed fault information is transmitted to the other side substation through communication. The digital fault locator includes MPU module, ADPU module, SIU module, and a power module. The MMI firmware and software of the fault locator was implemented.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.118-120
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• 2002

Voltage drop of low voltage distribution line is closely related with proper voltage regulation. It depends on the voltage drop of pole transformer, low voltage distribution line, and low voltage customer entrance line. Using above voltage drop factors, we proposes an estimation method of voltage drop in low voltage distribution line. Proposed method has been applied to a 22.9kV practical distribution system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.268-275
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• 2008

In this paper, we introduce a new method for detecting and estimating faults on a power line using the time-frequency domain reflectometry system. The system rests upon time-frequency signal analysis and uses a chirp signal which is multiplied by Gaussian envelope. The chirp signal is used as a reference signal, and we can get the reflected signal from a fault on a wire. To detect and estimate faults, we analyze the reflected signal by Wigner time-frequency distribution function and normalized time-frequency cross correlation function. In this paper we design an optimal reference signal for power line and implement a system for estimating fault distance on a power line with the TFDR implemented by PXI equipments. This approach is verified by some experiments with HIV 2.25mm power lines.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2139-2146
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• 2008

This paper presents a numerical algorithm for fault location estimation which used to data from both end of the transmission line. The proposed algorithm is also based on the synchronized voltage and current phasor measured from the PMUs(Phasor Measurement Units) in the time-domain. This paper has separated from two part of with/without shunt capacitance(short/long distance). Most fault was arc one-ground fault which is 75% over [1]. so most study focused with it. In this paper, the numerical algorithm has calculated to distance for ground fault and line-line fault. In this paper, the algorithm is given with/without shunt capacitance using II parameter line model, simple impedance model and estimated using DFT(Discrete Fourier Transform) and the LES(Least Error Squares Method). To verify the validity of the proposed algorithm, the EMTP(Electro- Magnetic Transient Program) and MATLAB did used.