• 전기의세계
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• 제26권6호
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• pp.78-85
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• 1977

This paper studies flashover voltage and surface corona loss of A.C and D.C in the mixed gas of air and SF$_{6}$ for solid insulators P.V.C, arcylic, glass and bakelite in two cases. In one case, those solids are covered with transformer oil and the other case, those solids are not covered with it. 1) The flashover voltage for each solids in SF$_{6}$ is more than three times compared with that in the air. The flashover voltage for P.V.C is the highest and then arcylic, glass, bakelite in a decreasing order. 2) The more the amount of SF$_{6}$ in the mixing ratio, the less corona loss. The P.V.C shows the least amount of corona loss and the bakelite the largest. 3) Compared with the corona loss of positive polarity and the negative polarity, the former has less corona loss than the latter. 4) The more the number of flashover discharge, the less insulation of each solids, but in case of bakelite, insulation almost vanishes after a couple of discharge. 5) When each insulator is covered with transformer oil, the flashover voltage generally increases and the corona loss decreases.eases.

• 대한기계학회논문집B
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• 제24권7호
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• pp.1002-1009
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• 2000

Among the various types of diesel after-treatment device, the corona discharge reactor may be considered as a powerful process for trapping submicron particles. But after precipitation on the electrodes occurs, the reentrainment of particles is severe and often causes low or negative precipitation efficiency. Experiments were performed to investigate the effect of an applied voltage on the reentrainment of soot particles from the electrodes. A co-annular laminar diffusion flame burner was used as the soot generator. When a highly negative voltage was applied, exfoliation of the deposited soot particles and an increase in concentration of particles smaller than approximately 150 nm were observed. Turbulence induced from the negative tuft corona and sputtering caused particle reentrainment from the corona wire and from plates as well. Under soot laden combustion gas, a streamer corona often occurred in the wire-cylinder reactor. Because of its transient nature, streamer corona violently increased the concentration of reentrained particles and CO gas.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.183-187
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• 2000

This paper deals with multiresolution analysis of wavelet transform for partial discharge(PD), both corona and surface discharge. Multiresolution analysis was used for performing discrete wavelet transform. PD signals was decomposed into "approximation" and "detail" components until 4 levels by using discrete wavelet analysis. In this paper, daubechies family is adopted for the research of the characteristics of PD signals. The results show that in corona discharge the segment 7, 8, 9, 10, 11 values of defined variable is increased with discharge process, so phase distribution is characterized by 210~330 ranges. In case surface discharge in expoxy insulator inserted, defined variable values is fairly symmetric discharge pattern because coupled both corona and dielectric bounded discharges. We can confirmly discriminate the type PD source. the type PD source.

• 전기학회논문지
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• 제58권10호
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• pp.2005-2010
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• 2009

Water droplet ejection characteristics of a point-to-plate airgap, with a wet porous point as a corona electrode, has been investigated. And the water droplet traces, charge, mass and number were measured experimentally. More particles are observed with wet porous point than metal point because the corona-discharging wet porous point can eject a number of water droplets. The water droplets ejected from the positive-corona-discharging wet porous point showed very fine traces as compared with those from the negative-corona-discharging wet porous point. Moreover, the water droplets ejected from the AC-corona-discharging wet porous point showed granular-like larger traces. It was shown that the weak corona discharge can eject smaller water droplets with larger ratio of mass-to-charge than the intense corona discharge.

• 한국식품과학회지
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• 제35권6호
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• pp.1237-1243
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• 2003

인삼 분말의 저장성을 증진시키기 위한 새로운 살균법으로서 고전압 상태에서 발생하는 코로나방전 처리법의 활용가능성을 평가하기 위하여 미생물살균효과, 이화학적 특성변화, 관능 특성을 비교?분석하였다. 코로나방전 처리한 인삼분말의 미생물 사멸효과를 살펴본 결과, 일반세균, 효모/곰팡이, 대장균군 모두 피크전압이 5 kv/cm 일 경우 미생물 사멸이 매우 미미하다가 피크 전압이 점차 증가할수록 비례적으로 사멸효과가 높아지는 결과를 볼 수 있었고, 피크전압 20 kv/cm의 코로나 방전 처리구에서 총 세균과 coliform은 약 95%, 효모/곰팡이는 약 99% 정도의 미생물 사멸효과를 나타내었다. 반면 코로나방전 처리한 인삼분말의 일반성분, 무기질, 유리당, 조사포닌, 색깔(Hunter's value) 모두 P<0.05 수준에서 유의적 차이를 보이지 않았다. 관능검사 역시 색깔특성, 향, 맛, 종합적 기호도 모든 측면에서 P<0.05 수준에서 유의적 차이를 보이지 않았다. 결론적으로, 코로나방전 처리는 인삼분말에서의 미생물 살균효과가 강하고, 영양소 파괴가 없으며, 관능적으로 무처리 인삼분말과 차이가 없는 것으로 밝혀져 기존의 방사선조사 처리 등 살균법을 대체할 수 있는 새로운 살균법으로서 활용 가능성이 높다고 판단된다.

• 한국재료학회지
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• 제5권2호
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• pp.178-183
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• 1995

본 연구에서는 상온에서 정방성 조성인 $Pb_{0.9888}Sr_{0.012}(Zr_{0.52}Ti_{0.48})O_{3}$계 세라믹스를 소결 후 직류전계 및 코로나를 이용하는 방법으로 소결시편을 분극한 후 분극방법에 따른 시편의 압전특성을 조사하였으며, 열화현상을 평가하기 위한 방법으로 시편의 내부응력의 차이를 조사하였다. 이 결과 코로나 분극방법은 직류분극에 비하여 $30^{\circ}C$정도 저온에서도 최대 Kp값을 얻을 수 있었으며 열화현상이 천천히 진행되었고 절연파괴가 발생하지 않는 등의 장점이 관찰되었다. 그러나 Kp값은 직류분극의 경우가 코로나 분극에 비하여 약 9~10%정도 높은 값을 나타내었다.

• 전기학회논문지
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• 제61권11호
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• pp.1656-1661
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• 2012

UV inspection technology is being used for predictive maintenance of power facility together with IR-thermography and ultrasonic devices. In this paper, the UV corona camera design, fabrication, and perform a simple test to be take advantage of the diagnostic equipment. The UV corona camera developed a $6.4^{\circ}{\times}4.8^{\circ}$ of the field of view as a conventional camera to diagnose a wide range of slightly enlarged, and power equipment to measure the distance between the camera and the distance meter has been attached. The transmission between 250 to 280nm was 11% ($12.5%{\times}88%{\times}98%$) by combing the transmission on absorption film, window and other filter(UG 5, nickel sulphate and so on). In a distance of 5m with the UV corona camera it is possible to detect partial discharge with a PD level of 2.5pC and a RIV level of $3.6dB{\mu}V$.

• Journal of Electrical Engineering and Technology
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• 제1권4호
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• pp.520-527
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• 2006

The electrical discharge and operational characteristics of needle and wire-cylinder corona charger based on current measurements for positive and negative coronas were evaluated and compared. A semi-empirical method was used to determine the ion concentrations in the charging zone and at the outlet of both chargers. Results from experimental investigation revealed that magnitudes of the charging current from the wire-cylinder charger were approximately 3.5 and 2 times smaller than those from the needle charger for the positive and negative coronas, respectively. The ion number concentrations at the outlet for positive corona of both chargers were higher than fur negative corona at the same voltage. Flow and electric fields in the charging zone of both chargers were also analyzed via numerical computation. Strong electric field strength zone was identified and led to high charging and particle deposition. Effect of particle deposition on the evolution of discharge current was presented. It was shown that ions loss inside the wire-cylinder charger was higher than the needle charger The particle deposited on the corona electrodes and on the grounded cylinder caused a great reduction in charging efficiency of both chargers.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.231-234
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• 2000

The corona in oil, the surface discharge in oil, the void discharge which could be in a transformer were imitated by using three electrodes with different shapes and the frequency bands of each ultrasonic signal were measured. After emitting artificial noises toward the transformer, only ultrasonic signals were extracted by frequency filtering, from the ultrasonic signals with noises at partial discharge. As a result, it was confirmed that the ultrasonic signals due to the corona in oil, the surface discharge in oil, the void discharge could be distinguished from the noises.

• 전자공학회논문지
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• 제51권8호
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• pp.195-201
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• 2014

본 논문에서는 도광판(LGP, Light Guide Panel)의 미세먼지 세정을 위해 건식 점착롤 제진과 코로나 대전을 이용한 제전(ESD, electrostatic discharge) 방식을 적용한 건식 세정 장치를 개발한다. 이를 위해 점착롤 제진과 제전 방식을 혼합 적용할 수 있는 세정 메커니즘을 설계하고, LGP를 자동으로 로딩/언로딩 및 이송할 수 있는 장치를 설계하고 구현한다. 그리고 이물질 및 미세먼지 세정 실험을 통해 개발된 시스템이 안정적으로 동작함을 확인하였다.