• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.35-40
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• 2012

In this study, the ultraviolet (UV) intensity of polymer insulator was measured using the Anti-Reflective (AR) coating lens on the occurrence of corona discharge. The UV intensity was compared before and after the AR coating. Under the 200-260[nm] of UV lens, the reflection rate before AR coating was 7.5~5.5[%] with 85-89[%] of transmission rate. After AR coating, however, the reflection rate decreased to 1.3~1.22[%] with improved transmission (97.4~97.6[%]). Then, the UV intensity by distance was measured in the polymer insulator. According to the measurement, the UV intensity increased 6.5 times at 37.5[%] of Vm/Vbd with 5[m] of distance. As distance increased, the growth rate declined. As high voltage increased, in addition, AR coating was less effective due to the count error caused by the UV sensor pulse signal overlap. Therefore, it appears that it would be more effective to detect corona discharge with 5[m] or less of distance at diagnosis of power facilities by AR coating and UV sensor sensitivity.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.386-391
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• 2014

Atmospheric-pressure nonthermal corona discharge plasma was applied to the sterilization of biologically contaminated scoria powder. Escherichia coli (E. coli) culture solution was uniformly sprayed throughout the scoria powder for artificial inoculation, which was well mixed to ensure uniformity of the batch. The effect of the key parameters such as discharge power, treatment time, type of gas and electrode distance on the sterilization efficiency was examined and discussed. The experimental results revealed that the plasma treatment was very effective for the sterilization of scoria powder; 5-min treatment at 15 W could sterilize more than 99.9% of E. coli inoculated into the scoria powder. Increasing the discharge power, treatment time or applied voltage led to an improvement in the sterilization efficiency. The effect of type of gas on the sterilization efficiency was in order of oxygen, synthetic air (20% oxygen) and nitrogen from high to low. The inactivation of E. coli under the influence of corona discharge plasma can be explained by cell membrane erosion or etching resulting from UV and reactive oxidizing species (oxygen radical, OH radical, ozone, etc.), and the destruction of E. coli cell membrane by the physical action of numerous corona streamers.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.645-647
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• 1993

Surface breakdown characteristics are investigated under metallic-particle contaminated conditions in $SF_6$ gas. The main results show that a rib increases breakdown voltage by a corona stabilization effect and the elongation of discharge path. The breakdown voltage at higher pressures than 4 atm may be estimated on the basis of mean breakdown field strength($E_{BD}$) and discharge length(L) which depend on gas pressure and surface shape.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.3
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• pp.215-220
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• 1999

$SO_2$and CO gas removal characteristics of a wire-to-cylinder type nonthermal discharge plasma reactor in various applied voltage (-dc, ac, fast rising pulse and high frequency pulse) and a crossed dc magnetic field have been investigated. The experiment has been emphasized on the oxidizing characteristics of $SO_2$ and CO gas by $O_3$ and the applying of a crossed magnetic field, which would induce the cyclotronic and drift motions of electrons making the residual time longer in the removal airgap space. And it also would enhance the energy of electrons and the electrophysicochemical actions to remove the pollutant gases effectively. It is found thatthe corona onset voltage and the breakdown voltage were decreased with increasing the crossed magnetic field and decrease initial fed $SO_2$and CO concentration. As a result, a higher ozone generation and $SO_2$ and CO gas removal rate of 20[%] can be obtained with -dc, ac and fast rising pulse corona discharges in the crossed dc current-induced magnetic field. But high frequency pulse didn't show effect in applying of a crossed magnetic field.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1574-1575
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• 2011

The application of a pulsed power system is being extended to an environmental and industrial field. The non-destructive gaseous pollutants from industrial plants such as power generation plants and incinerators can be processed by applying high voltage pulses with a fast rising time (a few nanoseconds) and short duration (nano to microseconds) in a pulsed corona discharge reactor. The pulsed plasma generator with a triggered switch has been developed. Its corona current in load can be adjusted by applied voltage and repetition rate. We investigated the performance of the pulsed plasma generator by analyzing the concentration of ozone in small reactor. This paper describes the electrical characteristics of the pulse generator with a voltage of 30 kV at repetition rate of 50 PPS. In addition, we briefly discuss a configuration of the system and initial test results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2035-2040
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• 2008

The electrical discharge of high voltage direct current(HVDC) overhead transmission line generate audible noise, radio noise, electric field, ion current and induced voltage on the ground. These items are major factors to design environmentally friendly configuration of DC transmission line. Therefore, HVDC transmission lines must be designed to keep all these corona effects within acceptable levels. Several techniques have been used to assess interference caused by ions on HVDC overhead transmission line. In this study, to assess the ion characteristic of DC line, the ion current density and induced voltage caused by ion flow were measured by plate electrodes manufactured from a metal flat board and charged bodies, respectively. The charged body has two types of cylinder and cylindrical plate. From the results of calibration experiments, the sensitivity of flat electrode and charged body can be obtained. At present, the developed system is used to investigate the ion generation characteristics of Kochang DC ${\pm}500kV$ test line.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.563-565
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• 1993

This paper describes ozone concentration and discharge characteristics in flowing $O_2$ with variation of Re at high voltage nozzle(HVN). HVN type ozonizer is equipped with ten nozzle. The important conclusions obtained from this paper are as follows. For constant pulse width(Pw) and pulse frequency(Pf) the more Re increases, the higher corona onset voltage(Vc) rise. Vc is inversely proportional to Pw and Pf. Ozone concentration($O_{3con}$) increases with less Re for constant Pw and Pf. $O_{3con}$ increases with less Pw. $O_{3con}$ is proportional to Pf.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.66-71
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• 1998

A compact ESP of two-stage type is widely used with positive corona discharge in working environment where the production of ozone is extreamly prohibited. Since there are few scientific reports on a compact ESP, we have investigated the fundamental characteristics of a two-stage ESP. A model two-stage ESP is made with simple structure in order to simplify theoretical analysis and the relative position of the ionizer and collector section can be changed. The experimental investigation revealed many interesting facts.: The electric field in the collector electrodes affects the corona discharge of the ionizer. The concentration of particles after collector remarkably varied in the region between the high voltage and grounded electrodes. The collection efficiency right behind the high voltage electrode is much greater than that behind the grounded one. The total collection efficiency, calculated by integrating the particle concentration in whole measuring region, is greater when the high voltage electrode of the collector is located behind the discharge electrode of ionizer. Thus, the relative position of the ionizer and collector electrodes affects the precipitation characteristics.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.293-300
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• 2014

This paper proposes a novel pattern recognition approach based on the radial basis function (RBF) neural network for identifying insulation defects of high-voltage electrical apparatus arising from partial discharge (PD). Pattern recognition of PD is used for identifying defects causing the PD, such as internal discharge, external discharge, corona, etc. This information is vital for estimating the harmfulness of the discharge in the insulation. Since an insulation defect, such as one resulting from PD, would have a corresponding particular pattern, pattern recognition of PD is significant means to discriminate insulation conditions of high-voltage electrical apparatus. To verify the proposed approach, experiments were conducted to demonstrate the field-test PD pattern recognition of cast resin current transformer (CRCT) models. These tests used artificial defects created in order to produce the common PD activities of CRCTs by using feature vectors of field-test PD patterns. The significant features are extracted by using nonlinear principal component analysis (NLPCA) method. The experimental data are found to be in close agreement with the recognized data. The test results show that the proposed approach is efficient and reliable.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.91-96
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• 2001

Ultrafine particles have been widely used in many high technology industrial areas. The spherical nonagglomerated and uniform nanometer-size $SiO_{2}$ particles are synthesized by the injection of TEOS vapor, ions and reaction gas in furnace. Ions were generated by Corona discharge electrode and these ions charge $SiO_{2}$ particles. As a result, spherical, nonagglomerated and ultrafine particles are generated in various conditions, it's morphology, charging portion and size distribution are examined by using TEM, ESP and SMPS. As the applied voltage of electrode changes from 0 kV to 5.0 kV, it is observed that the mean diameter of $SiO_{2}$ particle decreases from 94 nm to 42 nm.