• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.10
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• pp.570-576
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• 2000

The discharge and the collection efficiency characteristics of an electrostatic precipitator have been studied under various operating conditions. The specific resistivity of pulverized coal dust was about 1013∼1014[${\Omega}{\cdot}cm$] and reached the maximum value of 6${\times}$1013[${\Omega}{\cdot}cm$] at 150[$^{\circ}C$]. Back corona has been occurred as dust contents and gas temperature increase. In the case of back corona occurrence, collection effciency decreased rapidly. This problem has been solved by increasing moisture contents. Experimental results showed that collection efficiency of the full wave voltage was higher than that of the pulse wave voltage. The modification parameter k of the collection efficiency equation was about 0.42.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.146-150
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• 2001

전기집진기는 여타의 집진 설비에 대한 집진 효율과 유지 보수성이 우수한 설비이며 소결공장의 배출분진과 같은 고온($120{\~}160^{\circ}C$)의 미세분자($5{\~}12{\mu}m$) 및 고비저항($10^{12}{\~}10^{13} {\Omega}cm$)을 포집할 때 DC 하전에 비해 Pulse 하전이 효과적이며 Energy 절감이($60{\~}90\%$) 된다. 본 논문은 소결공장의 DC 하전에서 Pulse 하전으로 전환 시 EP 특성 및 부하변화에 따른 제어방안을 제시한다. 현재 제철소의 소결 전기집진기 경우 정수 직후에는 전압이 정상적으로 공급하다가 시간이 지남에 따라서 DC 전압이 낮아지고 Back Corona 현상이 발생하여 서서히 분진농도는 급격히 상승하는 문제점을 가지고 있다. 이에 비해 Pulse 하전으로 운전할 경우에는 Back Corona 현상 발생억제로 출구농도 상승 기울기를 조장방법 및 Ramping 장치와 관련장치 등을 최적으로 운용할 수 있는 방법을 소결공장 실험하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1637-1640
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• 2005

This paper presents a technique for electromagnetic field analysis on surge response due to Mid-span back-flashovers effects in lightning protection system of 500 kV EHV single circuit transmission tower by the neural networks method. These analyses are based on modeling lightning return stroke as well as on coupling the electromagnetic fields of the stroke channel to the line. The ground conductivity influences both the electric field as well as the coupling mechanism and hence the magnitude and wave shape of the induced voltage. The technique can be used to analyzed the corona voltage effect, the effective of stroke to the span tower, the surge impedance of transmission lines. The maximum voltage from flashovers effects in the lines. The model is compatible with general electromagnetic transients programs such as the ATP-EMTP. The simulation results show that this study analyses for time-domain with those produced by a cascade multi-section model, the surge impedance of a full-sized tower hit directly by a lightning stroke is discussed.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.270-272
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• 2000

석탄 화력 발전소 둥에서 배출되는 입자상의 분진은 대부분 고 비저항 분진이며, 분진의 전기저항치가 $10^{12}$ $\Omega$-cm 이상의 초고전기저항 분진에 대하여 역코로나 방지대책으로 S $O_3$ 주입기술이 있는데, 기존의 화학적인 주입설비는 매우 고가이다. 이에 본 연구에서는 배가스중의 S $O_2$ 가스를 전기 코로나 플라즈마에 의하여 S $O_3$로 변환시켜 궁극적으로 고 전기저항 분진의 전기저항을 저하시켜 고집진 효율을 달성하고자 하는 시스템에서 이에 대한 타당성을 검증하기 위하여 실험실 규모의 기초실험을 수행하였다(H. Szwed and St. Bach, 1996). (중략)

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.8-15
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• 2001

An aftertreatment system of diesel exhaust gas was attempted to extract particulate matters. The system consisted of a corona-less electrostatic precipitator to agglomerate soot particles and a counter-flow cyclone to collect them. When the effect of high voltage was examined at different configuration of electrode plates, the case of positive 15kV at both plates showed the maximum reduction of 38% in diesel smoke level. However, the back pressure became quite high as engine speed increased, so that minimizing pressure drop in cyclone should be studied with improving collection efficiency of soot particles.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.112-117
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• 2004

This paper describes the analysis of the UHF signal characteristics due to the partial discharge sources which can exist in a GIS. For the experiment, a model GIS was made and 5 types of discharge source were created as follows; corona discharge, surface discharge, void discharge, discharge due to free particle, discharge from floating electrode. The frequency spectra and the phase characteristics of UHF signals were induced by UHF signal analysis. The results were quantified to systematically adapt to analyze the PD sources in the GIS and utilized as algorithm data based on the neural network for Back-Propagation Algorithm with a multi-layer structure. The perception rate of the constructed algorithm showed approximately 94[%] and 82[%] in learning and testing data, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.4
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• pp.526-532
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• 2000

Recent studies have been directed toward obtaining a better understanding of the application of electrostatic precipitators to collect fly ash particles produced in a coal-fired power plant. Electrical resistivity can be described as the resistance of the collected dust layer to the flow of electrical current and is an important property for the collection efficiency in the electrostatic precipitator. In this paper, fly ash resistivity as a function of temperature up to $450^{\circ}C$ has been experimentally investigated using the resistivity meter consisted of the movable electrode, dust cup, and furnace. Resistivity was found to increase with increased temperature up to $200^{\circ}C$ due to the reduction of water concentration and then gradually decrease with increased temperature due to the activation of electrons. As the resistivity of fly ash in the flue gas temperature of $150^{\circ}C$ was measured >$10^{10}$ ohm cm, the efficiency of fly ash removal in the electrostatic precipitator might be expected to be low due to back-corona phenomenon. Flue gas conditioning in the electrostatic precipitator to reduce the resistivity of fly ash as required.

• Korean Journal of Organic Agriculture
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• v.29 no.1
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• pp.1-23
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• 2021

The form of agri-food transaction has taken a rapid change from the existing method since Covid-19. In response to changes in the market environment such as Covid-19, the integrated marketing organization in Jeollabuk-do was diagnosed from the point of view of innovation, and the future direction was examined. In order to improve the distribution structure of the production area, an integrated marketing organization was fostered, and both quantitative and qualitative growth were brought about. However, some regions still lack willingness to participate and lack of expertise. In particular, there is no infrastructure and strategy to prepare for the increase in non-face-to-face transactions post Covid-19. Online transactions also require economies of scale, so non-face-to-face transaction capabilities must be reinforced by adding a separate organization and experts in charge of online transaction functions within the integrated marketing organization. In the future, online sales are highly likely to expand not only to transactions between producers and individual consumers (C to C), but also to mass consumer (B to B) transactions. It will be an opportunity. In addition, it is necessary to efficiently use production area distribution facilities such as sorting and packaging. Since the non-contact transaction method will increase after Corona 19, it is necessary to strengthen marketing capabilities such as expansion of utilization rate, order placement, settlement, and customer management, and reorganization of specialized organizations.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.12
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• pp.624-630
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• 2001

The trend of the regulations on environmental issues are getting tight. Responding to this trend new technologies such as moving electrodes, wide pitch and pulsed power supply are also introduced in the electrostatic precipitator(EP) systems. The introduction of wide pitch and moving electrodes enhances the system performance of the EPs by improving air-flow and by improving the ash reentrainment on rapping. The power supplies for the EPs developed up to date include thyristor-based dc or intermittent type, SMPS(switching mode power supply) type and the pulsed-power supply type. The use of the pulsed ones is known to improve dust-collecting efficiency of high resistivity ash and reduces back corona occurrence in the collecting plate. There are two kinds of pulsed-power supplies; one with pulsed transformers and the other with direct dc switching devices. The latter uses rotary spark gap switches or semiconductor switches. Both have the merits and demerits: the spark gap switches are simple and robust but has short life time, hence, high maintenance cost, whereas the semiconductor switches have long life time but are costly. In this study, A high voltage power supply with superimposing voltage pulse on dc source was developed for EPs. This study describes circuit topology, operating principle of the scheme, and analysis of experimental results on Dong-Hae Power Plant. The pulsed power supply consists of a variable dc power supply with ratings of 60kV, 800mA and pulse generator which is made of high voltage thyristor-diode switch strings, an LC resonant tank and a blocking inductor. The pulse generator generates variable pulse-voltage up to 70kV using a high frequency resonant inverter with a variable dc source. Two prototypes were built and tested on 250MW DongHae power plant to verify the possibility of the commercial use and the normal operation in the transient states.

• Particle and aerosol research
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• v.14 no.4
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• pp.89-95
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• 2018

People's environmental concerns for fine particles in Korea lead to the strong necessity of improving the performance of environmental control systems. Wet electrostatic precipitators (ESPs) are considered as one of the alternatives to overcome the limit of previous dry ESPs, the re-entrainment of collected particles during rapping and back corona problem for high electrical resistivity dusts etc. In this study, a wire-cylindrical ESP with a thin water film has been developed. Particle collection characteristics were compared in the ESP with operations of water film on and off. Particle collection efficiencies at various applied voltages as well as voltage-current curves were almost the same in the ESP with and without a water film. Particle collection performance for PM1.0, PM2.5 and PM10 in the wet ESP with a water film was constantly maintained with operation time even in the high dust loading environment. This results indicate that a uniform water film in our wet ESP was successfully formed with a very thin layer without any dry spot and therefore could continuously clean the collected particles on the inner wall of the ESP without any performance degradation.