• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.5
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• pp.44-51
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• 2008

UV lamp systems have been used for cleaning of display panels of TFT LCD or Plasma Display Panel (PDP). However, the needs for high efficient cleaning and low cost made high voltage plasma cleaning techniques to be developed and to be improved. Dielectric-Barrier Discharges (DBDs), also referred to as barrier discharges or silent discharges have been exclusively related to ozone generation for a long time. In this paper, a 6kW high voltage plasma power supply system was developed for LCD cleaning. The 3-phase input voltage is rectified and then inverter system is used to make a high frequency pulse train, which is rectified after passing through a high-power transformer. Finally, hi-directional high voltage pulse switching circuits are used to generate the high voltage plasma. Some experimental results showed the usefulness of atmospheric plasma for LCD panel cleaning.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.522-526
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• 2007

Since newly emerged disease, the Severe Acute Respiratory Syndrome (SARS), spread from Asia to North America and Europe rapidly in 2003, many researchers have tried to determine where the virus came from. In the phylogenetic point of view, SARS virus has been known to be one of the genus Coronavirus, but, the overall conservation of SARS virus sequence was not highly similar to that of known coronaviruses. The natural reservoirs of SARS-CoV are not clearly determined, yet. In the present study, the genomic sequences of SARS-CoV were analyzed by bioinformatics techniques such as multiple sequence alignment and phylogenetic analysis methods as well multivariate statistical analysis. All the calculating processes, including calculations of the relative synonymous codon usage (RSCU) and other genomic parameters using 30,305 coding sequences from the two genera, Coronavirus, and Lentivirus, and one family, Orthomyxoviridae, were performed on SMP cluster in KISTI, Supercomputing Center. As a result, SARS_CoV showed very similar RSCU patterns with feline coronavirus on the both axes of the correspondence analysis, and this result showed more agreeable results with serological results for SARS_CoV than that of phylogenetic result itself. In addition, SARS_CoV, human immunodeficiency virus, and influenza A virus commonly showed the very low RSCU differences among each synonymous codon group, and this low RSCU bias might provide some advantages for them to be transmitted from other species into human beings more successfully. Large-scale genomic analysis using bioinformatics techniques may be useful in genetic epidemiology field effectively.

• The Korean Journal of Mycology
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• v.15 no.3
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• pp.135-141
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• 1987

Interspecific heterokaryons were obtained by polyethylene glycol induced fusion of protoplasts from auxotrophic mutants of P. ostreatus+P. cornucopiae, P. ostreatus+P. florida, P. ostreatus+P. sajor-caju, P. florida+P. cornucopiae, P. florida+P. sajor-caju and P. sajor-caju+P. cornucopiae protoplasts. The Fusion products of protoplasts were induced by MCM+benomyl, but segregation of sectors were not identified. Interspecific fusion products of protoplasts between incompatible strains did not form true clamp connections and did not produce fruit bodies. For induction of fertility, interspecific heterokaryons crossed with their parents by hyphal anastomosis.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2344-2347
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• 2007

To generate negative ion, a small dielectric barrier discharge (DBD) plasma reactor was used in this study and operated by high AC voltage. With increasing of voltage, we can get more negative ions. However unfortunately, if the input voltage is too high, it will also cause formation of ozone which is very harmful to human being health. So the work of finding out the best condition of Voltage and frequency was carried out firstly. After several times of measurement, operating at 20 kHz frequency is the best condition generating high ion concentration without ozone. For the purpose of finding out the best reactor structure, two types of surface dielectric barrier discharge (DBD) reactors were examined to produce negative oxygen ions at the conditions of 20 kHz frequency. The results indicated that the surface DBD reactor with several small tips showed better characteristics for generation of negative oxygen ions at the same condition.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.12
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• pp.673-678
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• 2000

The dielectric barrier discharge(DBD) is a common method to create a nonthermal plasma in which electrical energy is used to create electrons with a high average kinetic energy. The unique aspect of dielectric barrier discharges is the large array of short lifetime(10ns) silent discharges created over the surface of the dielectric. A silent discharge is generated when the applied voltage exceeds the breakdown voltage of the carrier gas creating a conduction path between the applied electrode and grounded electrode. As charge accumulates on the dielectric, the electric field is reduced below the breakdown field of the carrier gas and the silent discharge self terminates preventing the DBD cell from producing a thermal arc. In fact, the most significant application of dielectric barrier discharges is to generate ozone for contaminated water treatment. Therefore, experiments were perfomed at 1∼2[bar] pressure using a coaxial geometry single dielectric barrier discharge for ozone concentrations and energy densities. The main result show that the concentration and efficiency of ozone are influenced by gas nature, gas quantity, gas pressure, supplied voltage and frequency.

• The KSFM Journal of Fluid Machinery
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• v.15 no.3
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• pp.46-50
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• 2012

Plasma actuator makes parallel flow on the wall surface by the interaction between plasma and neutral air particles. Dielectric barrier discharge (DBD) plasma actuator is widely studied as one type of plasma actuators, which consists of one electrode exposed to the environmental gas and the other encapsulated by a dielectric material. This paper is experimentally focused on the performance of DBD plasma actuator mounted on a flat plate, which depends on kinds of the electrode materials, their thicknesses and the supplied voltage including its frequency. We measured the velocity magnitudes of the induced flow by a stagnation probe as a performance parameter of the plasma actuators. The velocity profiles of the flow induced by the plasma actuators are similar in all measurement cases. The magnitude of the induced velocity is strongly influenced by the thickness of the electrodes and the frequency of the input voltage. The performance of DBD plasma actuators is related to the electric properties of the electrode materials such as the ionization energy and the electrical resistivity.

• Journal of Environmental Health Sciences
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• v.38 no.2
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• pp.159-165
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• 2012

Objectives: This experiment was carried out to elucidate the effect of discharged water on the disinfection of $Phytophthora$ $capsici$ and evaluate the water characteristics. Methods: The dielectric barrier discharges (DBD) plasma reactor system used in this study consisted of a plasma component [discharge, ground electrode and quartz dielectric tube], high voltage source, and air supply. The effects of water characteristics such as pH, ORP and conductivity and the disinfection effect of discharged water were investigated. Results: Experimental results showed that in the process of discharge, the pH decreased, whereas ORP and electric conductivity increased. When the discharge time was 30 min, $Phytophthora$ $capsici$ of 2.94 log was disinfected within 300 seconds. Disinfection performance of stored discharged water was maintained for three days; however the disinfection effect vanished after five days. When $Phytophthora$ $capsici$ was injected into the discharged water, the disinfection effect decreased after two days. Conclusions: It is considered that the main disinfection parameters of the discharged water were chemically active species such as $H_2O_2$ and $O_3$ and high ORP.

• Journal of Environmental Science International
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• v.21 no.4
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• pp.479-488
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• 2012

A Dielectric barrier discharge (DBD) plasma is shown in the present investigation to be effective of phenol degradation in the aqueous solutions in batch reactor with continuous air bubbling. Removal of phenol and effects of various parameters on the removal efficiency in the aqueous solution with high-voltage streamer discharge plasma are studied. The effect of 1st voltage (80 ~ 220 V), air flow rate (3 ~ 7 L/min), pH (3 ~ 11), electric conductivity of solution (4.16 ${\mu}S$/cm, deionized water) ~ 16.57 mS/cm (addition of NaCl 10 g/L) and initial phenol concentration (2.5 ~ 20.0 mg/L) were investigated. The observed results showed that phenol degradation was higher in the basic solution than that of the acidic. The optimum values on the 1st voltage and air flow rate for phenol degradation were 140 V and 6 L/min, respectively. It was considered that absorbance variation of $UV_{254}$ of phenol solution can be use as an indirect indicator of change of the non-biodegradable organic compounds within the treated phenol solution. Electric conductivity was not influenced the phenol degradation. To obtain the removal efficiency of phenol and COD of phenol over 97 % (initial phenol concentration, 10.0 mg/L), 80 min and 120 min were need, respectively. Phenol and COD degradation showed a pseudo-first order kinetics.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.181-188
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• 2006

In this study, we analyzed the effects of several process variables on the removal efficiencies of NO and $SO_2$ by the dielectric barrier discharge process combined with photocatalysts. The $TiO_2$ photocatalysts were coated onto the spherical-shaped glass beads as dielectric materials by the dip-coating method to analyze the effects of photodegradation reaction on the NO and $SO_2$ removal. As the voltage applied to the plasma reactor increases, or as the pulse frequency of applied voltage increases, the NO and $SO_2$ removal efficiencies increase. Also as the residence time increases, or as the initial concentration of NO decreases, the NO and $SO_2$ removal efficiencies increase. The higher the amount of $TiO_2$ particles coated onto the glass bead is, the larger the surface area of $TiO_2$ particles for the photodegradation reaction is and the NO and $SO_2$ are removed more quickly by the faster photodegradation reactions.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.273-276
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• 2008

본 연구에서는 Air 및 Oxygen을 원료가스 사용하여 원통형 오존발생기의 오존생성농도를 측정하여 오존발생량 및 오존생성 수율을 계산하였다. 오존발생기에서 발생된 오존을 오존접촉조내의 원수 30[L]에 기상 오존주입량 3[g/$m^3$]를 투입하여 오존접촉 시간의 변화에 따른 오존접촉 실험 6일 후의 녹조 특성을 조사하였다. 오존생성특성 결과 원료가스가 Air인 경우, 최대오존생성 농도는 유량 1.0[$\ell$/min] 에서 5.5[g/$m^3$], 최대오존발생량은 유량 5.0[$\ell$/min] 에서 1.0[g/h]를 얻을 수 있었고, 원료가스가 Oxygen인 경우, 최대오존생성농도는 유량 1.0[$\ell$/min] 에서 51.5[g/$m^3$], 최대오존발생량은 유량 4.0[$\ell$/min] 에서 4.5[g/h]를 얻을 수 있었다. 오존접촉 실험 6일 후에서 원수와 오존접촉시간 1분에서 녹조 현상을 관찰할 수 있었고 나머지 오존접촉시간에 따른 오존 처리 수에서는 녹조 생성을 관찰할 수 없었다.