• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.421-423
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• 2005

Power transmission lines have been playing a key role as the mainstay of national industry. When a power failure occurs, it can have severe effects on national security as well as national industry and economy. In this paper, we consider an insulator failure, which is one of the main causes of such a power failure. In spite of its importance, however, a shortage of manpower in the insulator maintenance field is getting more serious due to working environments with a high voltage and a high place. For this reason, a new active maintenance technique using a robot system is required to prevent such an insulator failure. In this paper, a new robot mechanism for insulator cleaning and inspection was developed. We confirmed its effectiveness through experiments.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1831-1834
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• 1996

Diagnosis of cable insulation degradation has important meaning from a viewpoint of reliability enhancement of CV cable systems. So, we diagnosed 3.3kV & 6.6kV CV distribution cable on live-line which is judged to a most poor installation condition because they have been used in water condition after installation at the Yeochon chemical complex. The paper describes the analysis of the measured data, the problems at diagnosis, and the items which are considered at the development of diagnosis technology and equipment hearafter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.315-316
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• 2006

A new cleaning robot system for live-line tension insulator string was developed to prevent an insulator failure, which can have severe effects on national security as well as national industry and economy. The robot moves along the insulator string using the clamps installed on its two moving frames. Especially, unlike the existing cleaning robots using jets of water or water/air, the robot system adopts dry cleaning method using a rotating brush and a circular motion guide. This robot system has control architecture consisting of a master control unit and two slave control units. We confirmed its effectiveness through experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.33-37
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• 2001

Recently, the HFPD measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Also HFPD testing is able to offer the judgement standard of degradation level of HV machine and can detect discharge signals in live-line. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.253-257
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• 2017

Nowadays, it is increasingly important to detect whether cables are live for the operator's safety if there is a sudden power failure. It is especially hard to detect the electrical field of an underground line because of shielding. This paper on detection of live-line states in cables studied the detection characteristics of the change in the magnetic field and axis as the frequency, voltage, and distance at the same load are changed using 3 axes. A search coil type was used as a magnetic field sensor with non-contact. We found that magnetic fields decrease proportionally to the square of the distance and the decrease of rated voltage with load effected to magnetic field. The magnetic field was detected by 3-axis sensors given correct proximity, but appeared as noise components beyond a distance of 2 cm.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1769-1770
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• 2007

To prevent an insulator failure, an automatic cleaning robot was developed for suspension insulator strings. The robot autonomously moves along the insulator string using the clamps installed on its two moving frames, and adopts a dry cleaning method using rotating brushes and a circular motion guide. In addition, a mechanized brush bristles and a voltage-balancing contactor are devised to increase cleaning efficiency and to prevent arc generation under live-line conditions, respectively. Moreover, a manual tool for its installation and removal is presented. We confirmed its effectiveness through experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.166-171
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• 2011

We use the electrical energy and it is essential energy in modern life, but we lay cable underground due to the issue for environment and safety. Safety for worker is still insufficient for the development of safety equipment and related research has been focused on the cable lifetime diagnosis at underground cable work. I have to develop live line detector around the magnetic field were investigated at underground cable. In this paper, we were investigated by variation of coil turns and load due to detection of magnetic field at lines around. And detected value of developing products compared with measured value of milli-gauss meter. As a result, the value of the number of coil turns was found to be proportional to the measured value. But turn-numbers increase showed that the weak noise. I could be confirmed that sensor showed the optimum value from 4,000 to 5,0000.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.351-356
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• 2018

Commonly, a live-line alarm can be used to measure the electric field strength of a high-voltage system to calculate its current, but it is hard to detect the electric field of shielded cables or concealed structures, such as underground distribution cables. Current sensors can detect the magnetic field in a single core wire, but they cannot determine the magnetic field about a double-core wire because the currents flow in opposite directions. Therefore, it is very difficult to detect certain current problems, such as a fault current in an extension line comprised of a double line. In this paper, to ultimately develop a sensor that can detect the current regardless of line conditions, we used a simulation to determine the concentration of the magnetic field dependent on the distribution of the external magnetic field and the path of each line's core.

• Journal of the Korean housing association
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• v.25 no.3
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• pp.155-164
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• 2014

The purpose of the study was to explore expectations of workforce entry preparers from non-capital regions on post-college housing and financial support from their parents. From July 26 to August 8, 2013, an on-line questionnaire survey was conducted to juniors and seniors in colleges nationwide and 692 useable responses were collected from college students who were from non-capital regions. Findings from this study are summarized as follows: (1) About 44% of the respondents expected to live apart from their parents and other relatives within two years from their college graduation and 48% of them expected to live in Seoul Metropolitan Area; (2) among those who expected to live apart from their parents and other relatives, 61% expected to be monthly renters; 75% expected to live in small-sized units such as studios; 85% expected parental support to afford post-college housing costs; (3) female respondents, younger respondents and/or respondents with a greater parent income showed more stronger expectation on parental support to afford housing costs; and (4) most respondents perceived influence of housing cost burden strong enough to affect their job choices.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.779-783
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• 1992

In recent years, it is strongly required to supply high quality electrical power without insulation failure in distribution power cables. Therefore the exact measurement and judgment ar out deterioration degree of cables are essential to increase that supplying reliability. This paper will introduce various diagnostic methods of off-line and live-line cables also propose the judgement criteria and newly trend of diagnostic technique at present.