• 한국환경과학회지
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• 제30권5호
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• pp.399-406
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• 2021

The dissolution of ionized gas in dielectric barrier plasma, similar to the principle of ozone generation, is a major performance-affecting factor. In this study, the plasma gas dissolving performance of a gas mixing-circulation plasma process was evaluated using an experimental design methodology. The plasma reaction is a function of four parameters [electric current (X₁), gas flow rate (X₂), liquid flow rate (X₃) and reaction time (X₄)] modeled by the Box-Behnken design. RNO (N, N-Dimethyl-4-nitrosoaniline), an indictor of OH radical formation, was evaluated using a quadratic response surface model. The model prediction equation derived for RNO degradation was shown as a second-order polynomial. By pooling the terms with poor explanatory power as error terms and performing ANOVA, results showed high significance, with an adjusted R² value of 0.9386; this indicate that the model adequately satisfies the polynomial fit. For the RNO degradation, the measured value and the predicted values by the model equation agreed relatively well. The optimum current, gas flow rate, liquid flow rate and reaction time were obtained for the highest desirability for RNO degradation at 0.21 A, 2.65 L/min, 0.75 L/min and 6.5 min, respectively.

• 한국환경보건학회지
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• 제39권3호
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• pp.289-299
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• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.734-738
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• 2003

The addressing time should be reduced by modifying cell and/or driving method in order to replace the dual scan system by single scan and increase the luminance in large ac plasma display panel(PDP). In this paper, the relationships between of discharge cell structure and addressing time in ac PDP are investigated. It is found out that the addressing time was decreased with decreasing gap of ITO electrode and thickness of transparence dielectric layer on the front glass. The decrease rates were 4% per $10{\mu}m$ and 4% per $5{\mu}m$, respectively. Also in cases of decreasing height of barrier rip and thickness of white dielectric layer on the rear glass, addressing times were at the rate of 4% per $10{\mu}m$ and 4% per $2{\mu}m$, respectively.

• 폴리머
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• 제29권6호
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• pp.581-587
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• 2005

상업용 폴리우레탄(PU) 필름의 표면 개질 목적으로 대기압에서 플라스마를 발생시키기 위한 dielectric barrier discharge(DBD) 구조의 평판형 플라스마 반응기 내에서 이온화된 아르곤 플라스마를 사용하였다. 플라스마 처리 공정변수인 처리 시간, 처리 RF-power, 아르곤 가스 유속을 변화시켜가며 접촉각을 측정하여 젖음성과 표면 자유 에너지 변화를 알아보았고, 필름 표면 위에 과산화물을 최대로 도입시키기 위해 플라스마 처리 공정변수를 최적화하였다. 대기압 플라스마 처리 시간 70초, RF-power 120 W, 아르곤 가스유속 6 liter per minute(LPM)에서 가장 높은 젖음성과 표면 자유 에너지 값을 보였고, 1,1-diphenyl-2-picrylhydrazy(DPPH) 법을 사용하여 PU 필름의 표면에 생성된 과산화물의 농도를 정량한 결과, 처리 시간 30초, RF-power 80 W, 아르곤 가스유속 6 LPM의 플라스마 처리 조건에서 최대 2.1 nmol/$\cm^{2}$의 과산화물이 생성되었다.

• 한국전자파학회논문지
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• 제25권8호
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• pp.857-863
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• 2014

전자기파와 플라즈마의 상호 작용을 결정하는 주요 변수는 플라즈마 주파수와 충돌 주파수이며, 이 둘은 각각 전자 밀도와 전자 온도로부터 계산할 수 있다. 이 두 값은 플라즈마 발생기 종류에 따라 결정되는 시간 의존적인 변수이다. 기존의 전파 흡수 특성 연구에서는 수치 해석적 모형의 부재로 인하여 플라즈마의 시간적/공간적 변화를 간략화하거나, 상수로 가정하여 수행하였다. 본 연구에서는 플라즈마 유체 모델을 도입하여 얻어진 시간 의존적 변수 값을 전자기파감쇠량 계산에 이용함으로써 해석의 정확도를 높이는 방식을 제안하였다. 해석 대상인 유전체 장벽 방전 플라즈마는 구조적인 단순함으로 인하여 1차원 분석만으로 플라즈마 분포의 시간적 변화를 반영할 수 있다. 본 논문은 한 주기 내에서 전자 밀도와 전자 온도를 추출하여 마이크로파 입사 시 시간적 흡수 특성 변화를 분석하였다. 또한, 전자 밀도와 전자 온도의 변화에 따라 감쇠량을 계산하여 감쇠 경향성을 분석하였다.

• Journal of electromagnetic engineering and science
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• 제17권3호
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• pp.153-158
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• 2017

This work reports on the effect of plasma area on the frequency characteristics of the monostatic radar cross section (RCS) of a square metallic plate. A dielectric barrier discharge (DBD) plasma actuator consisting of 10 rings is proposed. The actuator is fabricated in three different configurations such that only three inner rings, seven inner rings, and all rings can be biased. By applying an 18-kV bias at 1 kHz, the three types of DBD actuators generate plasma with a total area of 16.96, 36.74, and $53.69cm^2$, respectively, in a ring or circular form. The experimental results reveal that when the DBD actuator is placed in front of a $20mm{\times}20cm$ conducting plate, the monostatic RCS is reduced by as much as 18.5 dB in the range of 9.41-11.65 GHz. Furthermore, by generating the plasma and changing the area, the frequency of maximum reduction in the monostatic RCS of the plate can be controlled. The frequency is reduced by nearly 20% in the X band when all rings are biased. Finally, an electromagnetic model of the plasma is obtained by comparing the experimental and full-wave simulated results.

• Journal of electromagnetic engineering and science
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• 제18권1호
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• pp.63-69
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• 2018

This work demonstrates attenuation effects of plasma on waves propagating in the 26.5-40 GHz range. The effect is investigated via experiments measuring the transmission between two Ka-band horn antennas set 30 cm apart. A dielectric-barrier-discharge (DBD) plasma generator with a size of $200mm{\times}100mm{\times}70mm$ and consisting of 20 layers of electrodes is placed between the two antennas. The DBD generator is placed in a $400mm{\times}300mm{\times}400mm$ acrylic chamber so that the experiments can be performed for plasma generated under various conditions of gas and pressure, for instance, in air, Ar, and He environments at 0.001, 0.05, and 1 atm of pressure. Attenuation is calculated by the difference in the transmission level, with and without plasma, which is generated with a bias voltage of 20 kV in the 0.1-1.4 kHz range. Results show that the attenuation varies from 0.05 dB/m to 9.0 dB/m depending on the environment. Noble gas environments show higher levels of attenuation than air, and He is lossier than Ar. In all gas environments, attenuation increases as pressure increases. Finally, electromagnetic models of plasmas generated in various conditions are provided.

• 한국환경과학회지
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• 제22권8호
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• pp.937-944
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• 2013

Ozone concentrations in water and air, and resulting disinfective properties, were measured following generation by either an ozone generator or a low-temperature dielectric barrier discharge plasma generator. In freshwater, ozone concentrations of 0.81 and 0.48 mg/L $O_3$ were observed after the ozone and plasma generators had been operated for five minutes, respectively. Higher levels of dissolved $O_3$ were attained more easily with the ozone generator. In seawater, both systems were capable of creating concentrations greater than 3.00 mg/L $O_3$ after 5minutes of operation. Higher ozone levels were attained more easily in seawater than in freshwater. Rates of bacterial sterilization in seawater after three minutes were 96% and 88%, using the plasma and ozone generators, respectively. In freshwater, higher concentrations of ozone were released into the atmosphere by the ozone generator than by the plasma generator. In creating equivalent levels of dissolved ozone in freshwater, the plasma generator released 4.5 times more ozone into the atmosphere than did the ozone generator. This shows that ozone generators are more effective than plasma generators for creating ozonated water. For the same concentration of dissolved ozone in seawater, more ozone was released into the atmosphere using the ozone generator than using the plasma generator. Therefore, with regard to air pollution, plasma generators seem to be less expensive than ozone generators.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1678-1683
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• 2003

DBD(Dielectric Barrier Discharge) plasma in air is well established for the production of large quantities of ozone and is more recently being applied to aftertreatment processes for HAPs(Hazardous Air Pollutants). Although DBD high electron density and energy, its potential use as nano and sub-micron sized particle charging are not well known. Aim of this work is to determine design and operating parameters of a two-stage ESP with DBD. DBD and ESP are used as particle charger and precipitator, respectively. We measured particle precipitation efficiency of two-stage ESP and estimated ozone decomposition of both pelletized $MnO_2$ catalyst and pelletized activated carbon. To examine the particle precipitation efficiency, nano and sub-micron sized particles were generated by a tube furnace and an atomizer. AC voltage of $7{\sim}10$ kV(rms) and 60 Hz is used as DBD plasma source. DC -8 kV is applied to the ESP for particle precipitation. The overall particle collection efficiency for the two-stage ESP with DBD is over 85 % under 0.64 m/s face velocity. Ozone decomposition efficiency with pelletized $MnO_2$ catalyst or pelletized activated carbon packed bed is over 90 % when the face velocity is under 0.4 m/s in dry air.

• 공업화학
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• 제24권1호
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• pp.87-92
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• 2013

광촉매 혼성 저온 플라즈마는 폐수에 함유된 유기물을 분해시키는 효과적인 기술이다. 본 연구에서는 광촉매가 결합된 특별히 설계된 유전체 방전 시스템을 골프장이나 감귤농가에서 흔히 살포되는 디크로보스, 카보퓨란 및 메치다치온 살충제의 분해에 적용하였다. 단독 및 병합 시스템에서 살충제의 분해를 평가하였다. 단독 시스템은 UV의 차폐 유무 및 산소기체와 공기에 의한 오존(각종 반응 활성종들 포함) 플라즈마를 이용하였다. 혼성 시스템은 UV로 활성화된 산화아연, 이산화티타늄과 그래파이트 옥사이드와 결합하여 공기에 의한 플라즈마 반응에 적용하였다. 그래파이트 옥사이드는 모사 허머스 법으로 제조하여 FT-IR 분광기로 성능을 측정하였다. 반응시간 60 min에서 UV를 차폐하고 공기를 이용한 플라즈마 반응에 의한 분해성능과 비교하였으며, UV로 활성화된 그래파이트 옥사이드(0.01 g/L)와 결합된 플라즈마 반응은 디크로보스와 카보퓨란의 각각 100% 분해도를 보였다. UV를 활용한 광촉매 혼성 플라즈마는 살충제를 분해시키는 효과적인 대안으로 입증되었다.