• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.1
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• pp.105-110
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• 2021

Objectives: The purpose of this study was to develop a new sterilization plasma device that would be proficient at sterilizing and removing pathogenic bacteria and viruses, and applicable to air purification systems. Methods: In order to understand the performance characteristics, the discharge characteristics of a packed bed DBD reactor and the ozone reduction characteristics of an ozone filter installed at the outlet of the reactor were investigated. Results: The novel packed-bed DBD reactor was proposed, and it was confirmed that the plasma discharge was uniformly and stably discharged throughout the entire layer, and sufficient ozone was generated for sterilization. The ozone filter was tested for three methods: adsorption, adsorption-decomposition, and catalytic decomposition. When the filter thickness was 30 mm, the ozone concentrations were 0.03 ppm, 0.01 ppm, and 0.21 ppm, respectively. The adsorption and adsorption-decomposition methods satisfied the EPA standard of less than 0.05ppm, but the catalytic decomposition method did not. Conclusions: It was confirmed that the adsorption-decomposition method has relatively excellent ozone filter performance and can provide the best ozone filter.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.78-82
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• 2003

For the decomposition of laundry wastewater containing Fe-EDTA produced from the steam generators in nuclear power plants, Supercritical Water Oxidation (SCWO) Process, Photocatalytic Oxidation (PO) Process, and Dielectric Barrier Discharge (DBD) Atmospheric Pressure Plasma Process were evaluated. Even though EDTA was converted over 99.98 % by the SCWO process, it was estimated that the countermeasure against corrosion of the equipment should be reinforced for the process stability. It was considered that the PO process is not appropriate for the decomposition of high concentrated laundry wastewater since the conversion ratio of EDTA was around 10 %. Finally, High efficiency of the decomposition of organic matter (methylene blue) was obtained using DBD process even low energy was supplied. However there is still room for the evaluation of EDTA decomposition in order that the DBD process should be applied for the field samples.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.486-491
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• 2016

Efficacy of dielectric barrier discharge-cold plasma treatment (DBD-CPT) for microbial decontamination of onion powder was evaluated. Onion powder, inoculated with Escherichia coli O157:H7, Salmonella Enteritidis, or Listeria monocytogenes, was treated with helium DBD-CPT. DBD-CPT (9 kV, 20 min) inhibited E. coli O157:H7, S. Enteritidis, and L. monocytogenes by $1.4{\pm}0.5$, $2.3{\pm}0.3$, and $1.2{\pm}0.0log\;CFU/cm^2$, respectively. The inactivation levels of E. coli O157:H7, S. Enteritidis and L. monocytogenes increased by $2.2{\pm}0.1$, $2.5{\pm}0.1$ and $1.9{\pm}0.3log\;CFU/cm^2$, respectively, as water activity increased from 0.4 to 0.8, and increased by $2.3{\pm}0.4$, $2.1{\pm}0.1$ and $1.6{\pm}0.1log\;CFU/cm^2$, respectively, as the particle size increased from 0.3 to $1.0cm^2$. Neither the ascorbic acid and quercetin concentrations nor the color of onion powder was changed by DBD-CPT (p>0.05). These results demonstrate the potential for application of DBD-CPT in improving microbiological safety of onion powder while preserving the physicochemical properties.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.183-189
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• 2007

We have investigated the oxidation of gas phase elemental mercury using dielectric barrier discharge (DBD). In the DBD process, active species such as $O_3$, OH, O and $HO_2$ are generated by collisions between electrons and gas molecules. Search active species convert elemental mercury into mercury oxide which is deposited into the wall of DBD reactor because of its low vapor pressure. The oxidation efficiency of elemental mercury has been decreased from 60 to 30% by increasing the initial concentration of the elemental mercury from 72 to $655{\mu}g/Nm^3$. The gas retention time at the DBD reactor has showed the little effect on the oxidation efficiency. The more oxygen concentration has induced the more oxidation of elemental mercury, whereas there has been no appreciable oxidation within pure $N_2$ discharge. It has indicated that oxygen atom and ozone, generated in air condition determine the oxidation of elemental mercury.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.5
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• pp.625-632
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• 2004

Perfluorocompounds ($PFC_s$), such as tetrafluoromethane ($CF_4$) and hexafluoroethane ($C_2F_6$), have been widely used as plasma etching and chemical vapor deposition (CVD) gases for semiconductor manufacturing processes. Since these $PFC_s$ are known to cause a greenhouse effect intensively, there has been a growing interest in reducing $PFC_s$ emissions. Among various $CF_4$ decomposing techniques, a dielectric barrier discharge (DBD) is considered as one of a promising candidate because it has been successfully used for generating ozone ($O_3$) and decomposing nitrogen oxide (NO). Firstly, optimal concentration of oxygen for $CF_4$ decomposition was found to figure out how many primary and secondary reactions are associated with DBD process. Secondary, to find effective discharge method for $CF_4$ decomposition, a streamer and a glow mode in DBD are experimentally compared, which includes (i) coaxialcylinder DBD, (ii) DBD reactor packed with glass beads. and (iii) a glow mode operation with a helium gas. The test results showed that optimal concentration of oxygen was ranged 500 ppm~1% for treating 500 ppm of $CF_4$ and helium glow discharge was the most efficient one to decompose $CF_4$.

• Proceedings of the KSME Conference
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• 2003.04a
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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.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1352-1353
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• 2008

In this study, aluminium - doped zinc oxide (ZnO:Al) transparent conducting film was deposited on PET(polyethylen terephthalate) substrate by r.f. magnetron sputtering method. PET substrate was surface-treated in an atmospheric pressure DBD(dielectric barrier discharge) plasma to increase deposition rate and to improve electrical propesties. Morphological changes by DBD plasma were obsered using contact angle measurement. The contact angle of water on PET was reduced from 62$^{\circ}$ to 42$^{\circ}$ by DBD plasma surface treatment. The plasma treatment also increased deposition rate and electrical propesties. The electrical resistivity as low as $4.97{\times}10^{-3}[{\Omega}-cm]$ and the deposition rate of 234[${\AA}$-m/min] were obtained in ZnO:Al film with surface treatment time of 5min, and 20min., respectively.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.213-217
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• 2007

Decomposition of benzene and selectivity of byproducts were investigated by using Dielectric Barrier Discharge (DBD) at atmospheric pressure. In order to increase the decomposition rate and selectivity of byproducts, two types of catalysts, H-ZSM-5 and Na-Y, were optionally employed inside the reactor of the process. The decomposition efficiency of benzene was investigated on the DBD and DBD/catalyst systems at various processing parameters including discharge voltage, residence time, and concentration of benzene. The results showed that, compared with the DBD only, the catalyst-assisted DBD process as a hybrid discharge type had an improved decomposition efficiency at the same process conditions of discharge voltage and residence time

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.8
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• pp.857-863
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• 2014

In determining interaction between plasma and electromagnetic wave, plasma frequency and collision frequency are two key parameters. They are derived from electron density and temperature, which vary in an extremely wide range, depending on a plasma generator. Because the parameters are usually unknown, traditional researches have utilized simplified electron density model and constant electron temperature approximation. Introduction of plasma fluid model to electromagnetics is suggested to utilize relatively precise time dependent variables for given generator. Dielectric barrier discharge(DBD) generator is selected due to its simple geometry which allows us to use one dimensional analysis. Time dependent property is analyzed when microwave is launched toward parallel plate DBD plasma. Afterwards, attenuation tendency with the change of electron density and temperature is demonstrated.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.458-458
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• 2012

Fuel Cell is used stacking metal or polymer substrate. This hydro property of substrate surface is very important. Usually, surface property is hydrophilic. The surface oxidation of SUS is investigated through plasma treatments with an atmospheric-pressure dielectric barrier discharge (DBD) for increasing hydrophilic property. The plasma process makes an experiment under various operating conditions of the DBD, which operating conditions are treatment time, plasma gas mixture ratio, the plasma source supply frequency. Two kinds of SUS substrate, SUS-304 and SUS 316L, were used. Discharge frequency has a crucial impact on equipment performance and gas treatment. After the plasma treatment of a SUS plate, highly improved wettability was noted. But, when high oxygen supply, the substrate damaged seriously.