• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.671-678
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• 2003

Spacer dampers maintain the constant gaps between each conductor in a bundle conductor-transmission line, and are installed at proper intervals to keep a line from all sorts of damages derived from the vibration energy caused by mechanical or electrical external factors. It is most important to embody a technology which considers difficulties of maintenance and repair, and has optimum elements in order to prevent accidents such as destruction by fire or the snapping of a wire by the effect of vibration phenomenon coming from transmission line. In the present thesis, therefore, the analysis of vibratory characteristics of spacer damper is set up by analytical methods such as the analysis of conductor motion's governing equation, the equation of spacer damper's motion, spacer damper-fastened wire's motion in a span, and the numerical analysis of finite difference method. Furthermore, the installation distance between spacer dampers was scrutinized by simulations of various vibration phenomena which change at any time as actual conditions do, and hereafter we will be able to analyze all kinds of vibration phenomena coming from a boltless spacer damper with 6 bundle conductor for 765 k V transmission line based on new analytical methods.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.1
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• pp.23-28
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• 2002

In order to survey the radiation characteristics of pure line noise of unwanted noise from overhead high voltage AC transmission lines, a disk type gap noise generator was manufactured. Disk size which decides capacitance between the noise generator and earth was selected through preliminary indoor experiments and analysis by using surface charge method. The capacitance is one of principal parameters related to the injection of a proper noise current into lines. On the basis of the capacitance obtained from calculation, 5mm of space was given to the gap of the noise generator to be installed o test line and an aluminum disk of 60cm radius was made. The field experiments were performed with the noise generator hung on the Kochang 765 kV full scale test line. As the results, the useful data which can be used to analysis the radiation characteristics of noise from transmission lines were obtained. Those are the directivity of antenna toward the line, lateral profiles, frequency spectra, height pattern and so on.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.653-658
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• 2003

This study is represented a method to give connect to optical cable from accident site and reviewed the method to transmission a moving image to control centre by real time, following the study of image transmission method in copper cable section where is a main line of railroad communication. Concept of network is studied to use cable and equipment effectively, and it's also reviewed technology of digital image transmission system and image evaluation methods, in spite of the pixel of camera and monitor resolution determine quality of image when moving image transferring by point to point. In addition, this study is reviewed checks and considerations of image transmission equipment (codec) with various transmission methods in room test, and then examined and analyzed wire/wireless combined transmission methods at wayside.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.510-515
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• 2011

In this paper, an artificial transmission line coupler with slotted-triangular patches, which is compact and spacesaving structure, is proposed. The proposed structure has specific features of not only convenience for adjusting the characteristic impedance and the phase of its coupled line by varying the lengths of the slots of the artificial transmission lines in designing a coupler but also the maximized coupling value at less than ${\lambda}$/4 electrical length so that it can be designed in compact and small dimensions, while conventional coupled line couplers are generally limited in compact and miniaturized designs by their ${\lambda}$/4 transmission lines. A fabricated 15 dB test-coupler at 2.4 GHz band by proposed design method shows good agreement with theory and simulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.177-183
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• 2010

Overhead transmission lines in domestic area have been built by several different design standards of dip and ground clearance. This paper describes an experimental study for evaluating load capacity and dip margin in overhead transmission lines. Such design standards for selection of overhead transmission conductors, dip and ground clearance, as well as electrical equipment technical standard are discussed. Based on daily load and weather data, several characteristics such as line utilization factor, load factor, conductor temperature and dip, etc. are analyzed, and compared with the specified levels of design standards. As a result, it is verified that DLR method can be a clue of the solving of the problem, for occurring in old transmission conductors which may be rarely operating below standards.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.45-52
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• 2001

This paper presents a study on the assessment of fuzzy measure possibility for the electromagnetic field of unbalanced system. It takes into account m untransposed transmission line and unbalanced load. A three phase load flow program was developed which employs a Newton-Raphson method as a tool to analyze system unbalanced. This research presents a method of handling two coupled three phase transmission system unbalance analysis and unbalanced power demand as a function of voltages. In assessment of fuzzy measure possibility for the electromagnetic field, this paper use probability of fuzzy and measure of fuzziness technique.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.542-544
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• 2005

Recently, the principal processes of T/L design tend to computerize and therefore integrated T/L design system has been developed. Since, it makes the automatic selection of T/L route, tower position and optimum design possible, computerized design method is applied all over the world. KEPCO introduced Optimal PowerLINE for T/L design in Myanmar 500kV project that is as a part of overseas project. And as a result of that work, effective and economical design was carried out. This paper presents the comparative analysis between Previous method and Optimal PowerLINE method for investigating practical application to Myanmar 500kV T/L design.

• ETRI Journal
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• v.32 no.3
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• pp.395-405
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• 2010

A novel multiclassifier system (MCS) strategy is proposed and applied to a text-dependent speaker verification task. The presented scheme optimizes the linear combination of classifiers on an on-line basis. In contrast to ordinary MCS approaches, neither a priori distributions nor pre-tuned parameters are required. The idea is to improve the most accurate classifier by making use of the incremental information provided by the second classifier. The on-line multiclassifier optimization approach is applicable to any pattern recognition problem. The proposed method needs neither a priori distributions nor pre-estimated weights, and does not make use of any consideration about training/testing matching conditions. Results with Yoho database show that the presented approach can lead to reductions in equal error rate as high as 28%, when compared with the most accurate classifier, and 11% against a standard method for the optimization of linear combination of classifiers.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.2
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• pp.121-133
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• 2003

This paper presents a fault location algorithm for a single phase-to-ground fault on 3-terminal transmission systems. The method uses only the local end voltage and current signals. Other currents used for the algorithm are estimated by current distribution factors and the local end current. Negative sequence current is used to remove the effect of load current. Five distance equations based on Kirchhoff's voltage law are established for the location algorithm which can be applied to a parallel transmission line having a teed circuit. Separating the real and imaginary parts of each distance equation, final nonlinear equations that are functions of the fault location can be obtained. The Newton-Raphson method is then applied to calculate the estimated fault location. Among the solutions, a correct fault distance is selected by the conditions of the existence of solution. With the results of extensive S/W and H/W simulation tests, it was verified that the proposed algorithm can estimate an accurate fault distance in a 154kV model system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1364-1370
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• 2014

Power system fault analysis has been based on symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. Obtaining accurate line impedances as possible are very important for estimating fault current magnitude and setting distance relay accurately. Especially, accurate calculation of zero sequence impedance is important because most of transmission line faults are line-to-ground faults, not balanced three-phase fault. Since KEPCO has started measuring of transmission line impedance at 2005, it has been revealed that the measured and calculated line impedances are well agreed within reasonable accuracy. In case of underground transmission lines, however, large discrepancies in zero sequence impedance were observed occasionally. Since zero sequence impedance is an important input data for distance relay to locate faulted point correctly, it is urgently required to analyze, detect and consider countermeasures to the source of these discrepancies. In this paper, development of pre/post processor to ATP (Alternative Transient Program) version of EMTP (Electro-Magnetic Transient Program) for sequence impedance calculation was described. With the developed processor ATP-cable, effects of ground resistance and ECC (Earth Continuity Conductor) on sequence impedance were analyzed.