• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.135-141
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• 2004

A sterilizer equipment by using electrical energy has metrits that no process of chemical and no second environmental pollution, Also, the power conversion circuit for sterilizer equipment has mertis that are reducing switching loss for soft switching topology by using zero current and zero voltage switching, and miniaturizing size of equipment. The proposed power device which has lower output current than other devices is possible to be compacted in it's size reduced it's price if the proposed power device is used for power system. Therefore, it is adapted for both less power consumption and sudden power conversion

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1480-1481
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• 2006

It is very difficult and dangerous to measure partial discharge from high voltage equipment in outdoor situation. But that is very important thing for preventing serious accidents from defects which originated in insulating degradation. This paper provides useful method to detect PD signals easily without any dangerous situation. Electric field sensor by the principle of capacitor detect PD signals without direct electrical connection between sensor and high power equipment and has very wide frequency range suitable for noise rejection. Electric field sensor and related circuit for processing PD signal showed good performance as a PD sensor when it is applied to simulated high power equipment generating PD pulse.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.444-450
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• 2008

There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the $8/20{\mu}s$ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.304-305
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• 2006

Now there is utilization of elevator increasing continuously, it is one of electrical facilities taking a serious view safety. However, elevator comfortable ride is researched generally Recently aging condition, equipment life, malfunction, other applicancies of power electronics and equipment disturbance effect on power quality and prevention measures are much researches in advanced nation. but awareness is lacking real condition up to now in domestic. Voltage sag, swell, harmonics, surge etc of elevator system is important problem about human safety. and there are many quality compensation to solve these problem of elevator. So to evaluate these problem, in this paper, displayed result through computer simulation for converter of problem, and inverter part by power quality problem in power distribution system.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.396-398
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• 2006

Predictive maintenance is not an unfamiliar concept because it has been used to predict the failures of electrical equipment such as transformers, motors and so on. By thoroughly monitoring the status of individual equipment and tracing how the various characteristics change over time, we can be aware of its exact condition and prevent the impending failure by taking appropriate actions. In this paper, I will extend the concept of predictive maintenance for individual electrical equipment to the power distribution system and show how to use the data obtained from power quality monitors to improve the power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.773-782
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• 2008

This paper describes the method for proper location of protective equipment in underground distribution cable through field test and analysis at testing lines. To prove the reliability for analysis simulated by EMTP/ATPDraw, the testing results obtained by the real test and the analysis for the same test lines were compared each other. The accuracy of analysis was proved by the comparison. Over voltages were measured and analyzed at each point of cable and switches in case of which lightning surge current was applied. The analysing method was applied to real distribution systems to select the proper location of protective equipment. It is evaluated that the location of protective equipment was properly selected.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.719-723
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• 1998

Prevention of the islanding phenomena is one of the most important issues because it can damage electrical equipment connected to the utility system and endanger human life. It is very difficult to detect an islanding condition of a power distribution line with conventional voltage of frequency relays, while the output power and the load power of utility interactive PV inverter units are in nearly balanced state in both active power and reactive power. This paper describes the protective equipment that prevents the PV system connected to the utility grid from starting islanding. Both predictive ocntrol method and harmonic injection method are used for a current control and islanding detection for operating safety.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1512-1519
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• 2013

Oil-impregnated paper is a major type of insulation used in oil-filled converter transformers for both traditional and new energy systems. This paper presents and analyzes the results of the experiment conducted on the electrical aging of oil-impregnated paper under AC-DC combined voltages using the pulsed electro-acoustic (PEA) technique. The formation and dynamics of space charge affected the performance of insulation material. The electrical aged oil-paper insulation was obtained through electrical aged experiments under the voltages. Based on the PEA technique, measurements were carried out when the oil-paper insulation system was subjected to different stressing and aging times. The space charge dynamics in the bulk of the oil-paper insulation system with different aging times were measured and analyzed. Characteristic parameters such as the total charge injection amount, the total charges of fast moving and slow moving, and the distortion factor of electric field were calculated and discussed. Results show that the longer electrical aging time, the more charges trapped in the bulk of aging sample. It leads to larger distortion factor of electric field in the bulk of aging samples and accelerate degradation of oil-paper insulation under AC-DC combined voltages.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.44-49
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• 2018

This study analyzed the Vulnerability of Network Communication devices when IEMI is coupled with the Network System. An Ultra Wide Band Generator (180 kV, 700 MHz) was used as the IEMI source. The EUTs are the Switch Hub and Workstation, which are used to configure the network system. The network system was monitored through the LAN system configuration, to confirm a malfunction of the network device. The results of the experiment indicate that a malfunction of the network occurs as the electric field increases. The data loss rate increases proportionally with increasing radiating time. In the case of the Switch Hub, the threshold electric field value was 10 kV/m for all conditions used in this experiment. The threshold point causing malfunction was influenced only by the electric field value. The correlation between the threshold point and pulse repetition rate was not found. However, in case of the Workstation, it was found that as the pulse repetition rate increases, the equipment responds weakly and the threshold value decreases. To verify the electrical coupling of the EUT by IEMI, current sensors were used to measure the PCB line inside the EUT and network line coupling current. As a result of the measurement, it can be inferred that when the coupling current due to IEMI exceeds the threshold value, it flows through the internal equipment line, causing a malfunction and subsequent failure. The results of this study can be applied to basic data for equipment protection, and effect analysis of intentional electromagnetic interference.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.169-171
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• 1995

Automatic control equipment in hydro power plant, such as turbine governor or automatic voltage regulator have to act promptly against for variation of power system, so it is necessary to check and test continuously. During last five years, the performance test of automatic control equipment was performed about 20 units of hydro turbine generator. In this process, because it has complex connection and before calibration, signal conditioner was developed as an auxiliary equipment for performance test. It includes function of signal amplifier, transducer, and meters. As a result of use this equipment for electric governor test at soyang-gang hydro power plant, it was possible to find output data equal to old one.