• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.145-155
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• 2002

It is essential for health monitoring of a cable-stayed bridge to provide more accurate and enough information from the sensors. In experimental modal testing, the chosen measurement locations and the number of measurements have a major influence on the quality of the results. The choice is often difficult for complex structures like a cable-stayed bridge. It is extremely important a cable-stayed bridge to minimize the number of sensing operations required to monitor the structural system. In order to obtain the desired accuracy for the structural test, several issues must take into consideration. Two important issues are the number and location of response sensors. There are usually several alternative locations where different sensors can be located. On the other hand, the number of sensors might be limited due to economic constraints. Therefore, techniques such as methodologies, algorithms etc., which address the issue of limited instrumentation and its effects on resolution and accuracy in health monitoring systems are paramount to a damage diagnosis approach. This paper discusses an optimum sensor placement criterion suitable to the identification of structural damage for continuous health monitoring. A Kinetic Energy optimization technique and an Effective Independence Method are analyzed and numerical and theoretical issues are addressed for a cable-stayed bridge. Its application to a cable-stayed bridge is discussed to optimize the sensor placement for identification and control purposes.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.19-21
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• 2009

The reflectometry for locating the fault at a cable is the same as a problem estimating the time delay between the incident and the reflected signals. In this paper, we propose a method for estimating the time delay between the two signals. The proposed method is based on the modeling of the Gaussian enveloped linear chirp signal in the Gaussian noise environment. The phase and the instantaneous frequency of the received signal are estimated by linear Kalman filtering. From the estimated instantaneous frequency, we can measure the time interval between the center frequencies of the incident and the reflected signals. The time interval is the same as the time delay between the incident and the reflected signals. In a simulation assuming that the cable has open fault at the end of the cable, the proposed method showed a good result in estimating the time delay.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.267-268
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• 2008

This paper presents compact low frequency ultra-wide band(UWB) sensor design and studying of the partial discharge diagnosis by sensing electromagnetic pulse emitted from the partial discharge source with new designed UWB sensor. In this study, we designed new type of compact low frequency UWB sensor based on microstrip antenna technology to detect both low frequency and high frequency band of partial discharge signal. And experiments of offline PD testing on in medium voltage (22.9kV) underground cable and mention the comparative results with the traditional HFCT as a reference sensor in the laboratory. In the series of comparative test, the calibration signal injection test provided with conventional IEC 60270 method and high voltage injection testing are included.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.47-47
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• 2010

배전계통의 사고예방 기술은 전력수요 및 증설이 증가하고 있는 상황에서 시급히 확립되어야 한다. 특히 현장에서 시공되는 케이블은 시공과정의 관리가 쉽지 않을 뿐 아니라, 시공 중 발생될 수 있는 결함들을 검출하는 방법도 제한되어 있다. 본 연구에서는 국내에 도입된 진단방법을 통계적 방법으로 분석하고 효과적으로 점검할 수 있는 방법에 관한 검토하고자 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.151-157
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• 2013

In this paper, properties of pattern using LBG (Linde-Buzo-Gray) Algorithm was explored including the exactness of K-means algorithm and process time of EM (Expectation Maximization) algorithm in order to develop analysis algorithm of partial discharge pattern in a cable using acoustic data analysis system. Partial discharge was measured by generating inner fault due to lamination of XLPE which is used for cable insulation material. Discharge pattern was analysed by changing the number of swarm article to 2, 4, and 6 in order to interpret swarm structure and properties.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1160-1161
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• 2015

In order to analyze and diagnosis on Location of partial discharge in underground distribution cable, partial discharges were measured using eletromagnetic sensors, oscilloscope, PDMS system at on-site underground multi-circuit switches. Throughout the analysis using 3-phase simultaneous pulse analysis and pulse polarity comparison of circuits, it is possible to separate noises and PD pulses and to find out the location of the pulses.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1193-1195
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• 1997

The chief advantage of these NCI, from a handling viewpoint. was an up to 90% weight reduction over their porcelain counter. Diagnosis and the life expectancy of NCI for transmission lines depend on a number of factors, many of which are associated with natural tracking breakdown, while others are related to manufacturing conditions. Recently The importance of optimizing a NCI for good performance under a wide variety of test condition and diagnosis is emphasized ; as well as the increased importance of natural breakdown testing. Today, at transmission lines, NCI have become very popular at 154 through 345 kV.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.2
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• pp.12-17
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• 2001

In this work, the correlation between the PD Patterns and the electrical tree propagation has been investigated by use of the specimen removed from the insulation of the real 154 kV XLPE underground power cables. As a result, it could be deduced that the PD pattern regarding electrical trees depends on their type which could be classified into three different distinct groups such as branch-bush mixed. Considering the results of our investigation, if the partial discharge magnitude is only considered for the diagnosis of the cable system, it is possible to draw a wrong decision. Therefore, it is possible to propose that the time characteristics of PD pattern should be taken into account for the diagnosis of the cable system in addition to the conventional $\Phi$-q-n characteristics.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1837-1839
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• 1998

This paper proposes the strain-insensitive temperature sensing in quasi-distributed sensor system using different thermal expension coefficient materials. This system has the high sensitivity and hasn't the necessity of reference signal. We can monitor the condition of the power cable with this system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.905-912
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• 2013

Power system fault analysis is commonly based on well-known symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. In case of balanced fault, such as three phase short circuit, transmission line can be represented by positive sequence impedance only. The majority of fault in transmission lines, however, is unbalanced fault, such as line-to-ground faults, so that both positive and zero sequence impedance is required for fault analysis. When unbalanced fault occurs, zero sequence current flows through earth and skywires in overhead transmission systems and through cable sheaths and earth in cable transmission systems. Since zero sequence current distribution between cable sheath and earth is dependent on both sheath bondings and grounding configurations, care must be taken to calculate zero sequence impedance of underground cable transmission lines. In this paper, conventional and EMTP-based sequence impedance calculation methods were described and applied to 345kV cable transmission systems (4 circuit, OF 2000mm2). Calculation results showed that detailed circuit analysis is desirable to avoid possible errors of sequence impedance calculation resulted from various configuration of cable sheath bonding and grounding in underground cable transmission systems.