• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.651-654
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• 1987

There are a number of small scale application fields of ozone, such as food conservation and/or storage in refrigerators, containers and storage rooms, deodorization in the production and living areas, protection against biohazards, bleaching of fabrics, etc. For these applications, miniaturization, ozone controllability and costdown of the ozonizer are the most essential points, whereas power efficiency is the most imporant factor in the case of a large scale ozonizer used in various industrial applications. It has been developed a novel sawtooth-to-cylinder type micro-ozonizer meeting above the three points by using a negative pulse corona discharge. As a result of the observations of pulse coronas affecting ozone generation, it is found that the maximum ozone concentration is generated at the pulse streamer coronas in both positive and negative case. The ozone concentration (20ppm/2l/min) generated by the negative pulse corona is about 2 times higher than that of the positive pulse corona, and could be controllable linearly by adjusting the dc input voltage of the [supply-inth ] cinventional small scale ozonizers. As a result, the present ozonizer is also very good to be used as a micro-ozonizer.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.49-53
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• 1996

Corona discharges in air insulated electric power systems cause power loss, produce interfering electromagnetic radiation, and can indicate incipient failure. An understanding of corona discharges in air gap is clearly Important. The Wavelet transformation is an extended method of fourier transformation. The fourier method is a powerful tool for signal analysis, but it can't include information for time. However the wavelet transformation analysis can include on the information of time and frequencies at the same time. In this paper we apply the wavelet transformation to the corona signals in needle-plane air gap for the purpose of analysis of developing aspects of corona discharges. We analyzed the developing aspects of corona discharges, namely, corona discharge current, repetition rates, width of Pulse distribution region, pulseless region and frequencies distribution of corona discharge pulses.

• 전기의세계
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• v.19 no.6
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• pp.18-25
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• 1970

The object of this project is to manifest the mechanism of deterioration phenomena for dielectrics causing corona discharge and applies it for determine the standard corona detection technique. As the results, we observed that corona discharges may occur more strongly around cylindrical shape electrode in air than hemisphere shape electrode in vacuum, so that it depends on effects such as shape of the electrode, moisture, surface coditions, etc. According to observed the deterioration of dielectrics takes place in following stages. At first the attacked surface by an electron avalanche is uniformly eroded; then pits are formed; after that sharp channels are formed which lead to break-down as a treeing. The test are accelerated with higher frequencies by the cylindrical bar shape electrode in the pulse stright detection method more sensitive than Lissajous patterns. Lissajous patterns detection method is simple but usually insensitive and has disadvantage that the magnitude of the individual discharge is not measured.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.44-51
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• 2000

In this paper, using a wide-band AE sensor with the frequency range from 100[kHz] to 1.5[kHz], the frequency spectra of AE signals generated from the corona discharges of the needle-plane gap and from the partial discharges of an epoxy void were analyzed to determine the proper ultrasonic sensor with optimum frequency range according to the patterns of corona discharges. We also examined the propagation characteristics of AE signals in oil and the relationship between the magnitude of corona discharge and the magnitude of AE signals in peak-to-peak value under the application of 60[Hz] ac high-voltage. From these results, the main frequency spectra of AE signals emitted from the corona discharges of the needle-plane gap were about 130[kHz] by the fast fourier transform, but the main frequency spectra appeared to be 230[kHz] in the partial discharges of an epoxy void. The magnitude of AE signals was proportional to the magnitude of corona discharge and discharge current pulse with increasing the applied voltages.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.38-46
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• 1999

Measurerments of ultrasonic signals caused by corona discharges were perforrred by using an ultrasonic meeasurerment technique to analyze the deve1qxrent states of coronas in a high-voltage power apparatus. We also examined the relationship between discharge magnitude and ultrasonic pulse number to diagnose the deterioration of electrical insulation by corona discharges. From these results, it was found that ultrasonic signals due to corona discharges can be firstly detected at the peak value of positive polarities prior to the breakdown voltages, and the magnitude of ultrasonic signals was closely related to the current pulses by the corona discharges when ac voltages were gradually raised, and it appeared that ultrasonic pulse number was proportional to discharge magnitude. Attenuation, tirre-delaying and directivity charocteristics of ultrasonic signals propagated to air by using ultrasonic oscillation and receiving systems are feJXlrt.ed as a basic data of ultrasonic measurements in out-door HV apparatus.aratus.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.12
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• pp.1032-1040
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• 2001

In order to apply the partial discharge measuring technique utilizing electrical pulse to the transformer at sites, this paper describes the measuring technique obtaining only the signals due to internal partial discharge in the transformer, but the noises due to external corona which has been a major problem so far. At first, partial discharge and corona noise were simultaneously generated in the model transformer by using needle-plane electrodes and rod-sphere electrodes out of it in a high voltage laboratory, respectively. It was verified that only the partial discharge signals in the transformer could be measured by removing the noise signals from the superposed signals of partial discharges and noises on the grounding wire of the model transformer. By application to a 345kV transformer in service, it was also confirmed that the partial discharge could be on-line monitored by removing the noise signals measured by the inductance sensor on the grounding wire of a 154kV lightning arrester from the superposed signals of internal partial discharge and external corona noise measured by bushing tap coupler of the transformer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.255-256
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• 2007

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.239-246
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• 2014

Incineration is conceptually sound as a waste treatment technology. There is, however, concern over its emissions when it is improperly designed and operated. An electrostatic precipitator is one of the most commonly used devices to control particulate emissions from boilers, incinerators and some other industrial processes. In this work, a modular electrostatic precipitator with sizing of $1m{\times}1m{\times}1m$ was developed for removal of particulate matter from the exhaust gases of a small waste incinerator. Its design was based on a simple wire-and-plate concept. The corona discharge wires were connected to a positive high-voltage pulse generator, while the collection plates were grounded. The high-voltage pulse generator was used to produce the corona discharge field between the individual discharge wire and the collection plate. The particulate-laden exhaust gas flow was directed across the corona discharge field. The charged particles were deflected outward and collected on the plate. The collection efficiency was evaluated as a mass loading ratio between the difference at the inlet and the outlet to the particulate loading at the inlet of the precipitator. The collection efficiency of this modular electrostatic precipitator design was approximately 80 %.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.78-83
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• 2014

To minimize the financial loss due to power facility malfunction, on-line diagnostic techniques are required to grasp any abnormal state of facilities in the live line as well as devices to diagnose abnormal states of power facility in an easy and prompt manner. This study aims to develop a portable UV detecting system by means of UV sensors for easier and efficient inspection of the degradation state of power facility in a long distance. Accordingly, it includes a simulation of corona discharges that may occur due to degradation of power facility and detection of ultraviolet pulse generation depending on the corona discharge intensity and measuring distance in application of UV sensors. Additionally, the optimal algorithm is determined for its application to the system's degradation diagnosis program based on the measured experiment data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.74-81
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• 2015

In the measurement of atmospheric static electric field, it is important to know characteristics of corona discharges caused at the tip of test electrode. This paper presents the fundamental data of DC corona discharges that occurred at the tip of a needle-shaped electrode placed in the homogeneous background electric field which simulates the atmospheric static field under thundercloud. The major characteristics of interest for this purpose are the polarity effect of corona discharges and the magnitudes and time intervals of corona current pulses. The experimental set-up consists of the plate-to-plate configuration with a needle-shaped protrusion, DC power supply, and voltage and current measuring devices. As a result of experiments, the polarity dependence of corona pulses is significantly pronounced. The time intervals between successive corona pulses in the negative polarity is much longer than those in the positive polarity. The time intervals for both polarities is drastically decreased as the applied electric field is increased. Also the magnitudes of the positive corona pulses are slightly changed with an increase in applied electric field, but those of the negative corona pulses are linearly increased with increasing the applied electric fields.