• Journal of Korean Society for Atmospheric Environment
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• v.19 no.3
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• pp.315-323
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• 2003

The goal of this study if the optimization of discharge electrode for pulsed corona discharge reactor located in thermal power plant. For this purpose, we have performed experiments of NO$_{x}$ removal rate by exchange of discharge electrode diameter and arrangement of discharge electrode in the non -thermal plasma reaction facility using a ethylene as additive. If the diameter and numbers of discharge electrode were larger, the NO$_{x}$ removal rate was higher. From these results, if we optimized the shape and installed numbers of discharge electrode at the pilot plant, we could increase the NO$_{x}$ removal rate with less amount of additive than current amount.mount.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1735-1737
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• 2001

The occurrence of fires under transmission lines is responsible for a great number of power line outages. In this paper, the ac flashover voltages and the corona onset voltages of a needle-plane electrode gap of vertical arrangement in the presence of flame were investigated. We also observed the corona discharge current and variation of shapes in flame with increasing the applied voltages. We found that the corona onset voltages and the flashover voltages were drastically decreased with the position of flames and gap length of electrodes, and observed that the deflection or fluctuation phenomena in the shape of flames.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1910-1912
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• 1996

This paper presents the results of laboratory experimentals to remove $SO_2$ and $NO_x$ by a pulsed corona discharge in the wire-plate reactor. A rotating spark gap switch was used to generate the pulse by chewing the dc high voltage. Repetition frequency of the pulse was 60Hz and rising time of 50ns. The photo pictures of positive streamer corona taken by ICCD camera, pulse voltage and current were measured using a digital oscilloscope. Simultaneous effects of $C_{2}H_{4}$ injection and heterogeneous chemical reactions on nonthermal plasma process to remove $SO_2$ and $NO_x$ from flue gas were investigated in the present study

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.453-455
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• 1995

In electrostatic airclean filter, the collection efficiency defends on particle charge in the ionizer section. The effect of electrostatic airclean filter condition (deposition of dust, variation of corona discharge current) on corona discharge characteristics was well studied. However, it seems not to be studied on corona discharge characteristics of electrostatic airclean filter respect to contaminated electrode which is caused by practical use. In this paper, Long-term(60days) effects are studied experimentally by two methods. The one is ozone concentration, the other is collection efficiency. Generation of ozone level was increased but collection efficiency was slightly reduced in long-term used electrostatic airclean filter.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1801-1803
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• 1997

The Gas Insulated Switchgear(GIS) has made it an indispensible part of power transmission network. In order that the GIS may have its high reliability, it is necessary to pay careful attention to its whole process e.g., designing, manufacturing, installation, and operation. The main hazard in GIS comes from free conducting particles, which can move and cause breakdown under the influence of the electric field. Although the concentration on protecting the GIS inner part against the free conducting particles is made, it is, actually, almost impossible to avoid the hazard from the particles throughly. In this paper, the corona discharge in GIS initiated by the free conducting particles was discribed through laboratorial experiment The magnitude of the corona discharge voltage was measured using current measuring method by the impedance. The purpose of this experiment is to get fundamental data which is essential to develop GIS diagnosis technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.140-143
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• 1992

This paper deals with the dielectric behaviors of $SF_{6}$ gas and prebreakdown growth caused by lightning impulse voltages in inhomogeneous field perturbed with a fixed needle-shaped protrusion on the electrode. The measuring interpretation of the external current induced by moving charges is described. The temporal growth of prebreakdown is obserbed by using a shunt and photomultiplier. The prebreakdown processes are initiated by the first streamer corona at a needle protrustion, the flashover of the main gap in the positive polarity is very sensitive to the local field and propagates into the gap with the leader mechanism. It is found that the dependence of the prebreakdown phenomena on the polarity of applied voltages is caused by the effect of space charges. In addition, the proposed measuring techniques are very useful to perform the measurements of avalanche currents, corona discharges in inhomogeneous fields ad partial discharges in voids.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1436-1437
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• 2007

This paper presents the experimental results of the dielectric characteristics with temperature changes under highly non-uniform electric field in $SF_6$ gas. The impulse preliminary breakdown developments were investigated by the measurement of predischarge current and breakdown voltage. As a result, the first stremer corona is initiated at the tip of needle electrode, and bridges the test gap. Also the first stremer corona onset and breakdown voltages the negative polarity was much higher than that in the positive polarity in same temperature. In addition, the varition of temperature have a little effect on the positive polarity. On the other hand, in some cases negative polarity corona onset and breakdown voltages increased with increasing a high temperature.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.241-249
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• 2022

The current research attempts to measure the level of the acceptance of the Blackboard System (BBS) during the Corona crisis, and whether this is one of the reasons for the low use of the BBS at Al-Jouf University. To achieve this, the technology accepting model in the time of crisis (TAMTC) has been proposed to measure the degree of acceptance by students, which was then applied to a random sample of 339 of such. The results show a high level of student acceptance, despite their lower use of the system. The research also highlights the importance of upgrading e-courses and that the discontinuation of exam disqualification of students is secondary to their poor course attendance.

• 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 Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.83-91
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• 2011

Even if smoke, fumes, mist or dust particles are removed by electrostatic precipitators (ESPs), the occurrence of ozone, which is harmful to human body, has to be severely restricted in the indoor environments of hospitals, offices, and workshops. Therefore, the two-stage ESP generating positive corona at the ionizer is typically used because it creates less ozone than the two-stage ESP generating negative corona at the ionizer. In order to predict the collection performance and the optimal design of the two-stage ESP applied to positive high-voltage, particle concentration is experimentally investigated in this paper. In addition, particle motion within the collector section is also numerically analyzed. The positive corona discharge current of the ionizer is found to be affected by the applied voltage in the collector section but less so by the particle concentration. Particle concentration shows a minimum near the high voltage electrode of the collector section. The minimum value of the collection efficiency is almost proportional to gas velocity. When the collector length decreases, the minimum value of the collection efficiency increases. Charged particles entering the collector region are linearly deflected towards the grounded plate by an electric field. From the above experimental and numerical results, two empirical equations on the concentration ratio and the collection efficiency are derived, and are in good agreement with the experimental data.