• Korean Journal of Materials Research
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• v.26 no.8
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• pp.406-411
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• 2016

In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate $TiO_2$ powder. The photocatalytic activity of the $TiO_2$ powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused $TiO_2$ cleaned by APDBD improved to a level up to 0.32h-1 higher than the 30 % value of the initial $TiO_2$ powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which $TiO_2$ effectively adsorbed MB at every photolysis stage.

• Journal of Aerospace System Engineering
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• v.11 no.6
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• pp.56-63
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• 2017

Thrust force induced by the dielectric barrier discharge inside of cylinder pipes is measured for various conditions. The input peak-to-peak voltage and frequency are varied from 2 to 9 kVpp and from 5 to 15 kHz, respectively. The height of cylinder is varied from 50 to 100 mm. The results of the measurements show that the magnitude of the generated thrusts increases as the voltage and the frequencies increase. It also shows that the generated thrusts are decreased according to the increase in the height of the cylinder. The cause of the thrust decrease is discussed in terms of energy losses due to the frictions on the wall surface.

• Korean Journal of Materials Research
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• v.33 no.4
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• pp.115-123
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• 2023

In this paper, we report and discuss the semi-permanently hydrophilic (SPH) treatment of polyester fabric using plasma polymerization and oxidation based on atmospheric pressure dielectric barrier discharge (APDBD) technology. SiO_xC_y(-H) was coated on polyester fabric using Hexamethylcyclotrisiloxane (HMCTSO) as a precursor, and then plasma oxidation was performed to change the upper layer of the thin film to SiO₂-like. The degradation of hydrophilicity of the SPH polyester fabrics was evaluated by water contact angle (WCA) and wicking time after repeated washing. The surface morphology of the coated yarns was observed with scanning electron microscopy, and the presence of the coating layer was confirmed by measuring the Si peak using energy dispersive x-ray spectroscopy. The WCA of the SPH polyester fabric increased to 50 degrees after 30 washes, but it was still hydrophilic compared to the untreated fabric. The decrease in hydrophilicity of the SPH fabric was due to peeling of the SiO_xC_y(-H) thin film coated on polyester yarns.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.552-552
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• 2013

In our study we consider Al2O3 ceramic substrates for Plasma Surface Treatments in order to improve deposited diamond surface and increase diamond deposition rate by applying DBD (Dielectric Barrier Dischrge) system. Because Plasma Surface Treatments was used as a modification method of material surface properties like surface free energy, wettability, and adhesion. By applying Plasma Surface Treatments diamond films are deposited on the Al2O3 ceramic substrates. DC Arc Plasmatron with mathane and hydrogen gases is used. Deposited diamond films are investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) is studied. As a result, nanocrystalline diamond films were identified by using SEM and diamond properties in XRD peaks at (111, $43.8{\Box}$, (220, $75.3{\Box}$ and (311, $90.4{\Box}$ were shown. Absorption peaks in FTIR spectrum, caused by CHx sp3 bond stretching of CVD diamond films, were identified as well. Finally, we improved such parameters as depostion rate ($2.3{\mu}m$/h), diamond surface uniformity, and impurities level by applying Plasma Surface Treatments. These experimental results show the importance of Plasma Surface Treatments for diamond deposition by a plasma source.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.176-177
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• 2016

In the last few decades, attention toward atmospheric pressure plasma (APP) has been greatly increased due to the numerous advantages of those applications, such as non-necessity of high vacuum facility, easy setup and operation, and low temperature operation. The practical applications of APP can be found in a wide spectrum of fields from the functionalization of material surfaces to sterilization of medical devices. In the secondary battery industry, separator film has been typically treated by APP to enhance adhesion strength between adjacent films. In this process, the plasma is required to have high stability and uniformity for better performance of the battery. Dielectric barrier discharge (DBD) was usually adopted to limit overcurrent in the plasma, and we developed the pre-discharge technology to overcome the drawbacks of streamer discharge in the conventional DBD source which makes it possible to produce a super-stable plasma at atmospheric pressure. Simulations for the fluid flow and electric field were parametrically performed to find the optimized design for the linear jet plasma source. The developed plasma source (Plasmapp LJPS-200) exhibits spatial non-uniformity of less than 3%, and the adhesion strength between the separator and electrode films was observed to increase 17% by the plasma treatment.

• Journal of IKEEE
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• v.23 no.2
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• pp.431-437
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• 2019

This work was carried out ozone generation and TCE decomposition characteristics using dielectric ball materials filled barrier discharge reactor and catalyst's reactor for ozone decomposition. Ozone concentration generated from $Al_2O_3$ or $TiO_2$ filled barrier discharge reactor was so high compared with non-filled discharge reactor. This reactor is good discharge structure for generating the high ozone concentration. In addition, TCE decomposition rate and COx conversion rate increased using $MnO_2$ filled discharge reactor, because ozone was decomposed at the same discharge space on the surface of $MnO_2$ catalysts. To identify the $MnO_2$ catalytic effects, TCE decomposition rate reached to 100[%] by the decomposition of ozone at $MnO_2$ catalyst's reactor by the arrangement of $Al_2O_3$ filled discharge reactor and $MnO_2$ catalyst reactor. Finally, $MnO_2$ catalyst is good materials for the decomposition of ozone and this process will be useful for decomposing VOCs such as TCE.

• Journal of the Korean institute of surface engineering
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• v.44 no.2
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• pp.50-54
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• 2011

Hydrophobic a-C:F film was coated on polycarbonate film with $CF_4$, $C_2F_6$ and HFC ($C_2F_4H_2$) gas in helium discharge generated by 5~100 kHz AC power supply at atmospheric pressure and room temperature. The highest water contact angle of the a-C:F film formed with $He/C_2F_6$ mixed gas is $155^{\circ}$. X-ray photoelectron spectrum showed that there was 40% of C-$CF_3$ bond at the surface of the super hydrophobic film. The contact angle and deposition rate were decreased with increasing substrate temperature. The contact angle was generally increased with the surface roughness of the film. The contact angle was high when the surface microstructure of the film was fine and sharp at the similar roughness and chemical composition of the surface.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1216-1221
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• 1999

GaN films were deposited on sapphire [$Al_2O_3(0001)$] substrates at relatively low temperature by MOCVD using N-atom source based on a Dielectric Barrier Discharged method. Ammonia gas($NH_3$is commonly used as an N-source to grow GaN films in conventional MOCVD process, and heating to high temperature is required to provide sufficient dissociation of $NH_3$. We used a dielectric barrier discharge method instead of $NH_3$ to grow GaN film relatively low temperature. DBD is a type of discharge, which have at least one dielectric material as a barrier between electrode. DBD is a type of controlled microarc that can be operated at relatively high gas pressure. Crystallinity and surface morphology depend on growth temperature and buffer layer growth. With the DBD-MOCVD method, wurtzite GaN which is dominated by the (0001) reflection was successfully grown on sapphire substrate even at $700^{\circ}C$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.335-335
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• 2012

금속 박막과 PI film 과의 접촉력을 증가시키기 위하여 remote - type modified dielectric barrier discharge (DBD) module을 이용하여 대기압 플라즈마 표면 처리를 실시한 결과, 접촉각이 매우 낮게 형성됨을 관찰 할 수 있었다.

• 전기의세계
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• v.14 no.2
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• pp.8-13
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• 1965

It is expected that the impurities contained in a solid state insulation material will affect a considerable influence on its break-down voltage, dielectric loss, and insulation resistance. In this thesis, as a preliminary experimental research for the investigation described above, the effect of metalic barrier between the electrodes on the creepin flash over discharge voltage along the surface of a solid insulation material has been investigated, and got some interesting results. It was found that generaly the flash over voltage rises when a metalic barrier is located between the electrodes. The results of this investigation will be taken into account as an important components on the insulation design to prevent the creeping flash over discharge in insulators, bushings, and so on.