• Journal of Korean society of Dental Hygiene
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• v.14 no.5
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• pp.783-788
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• 2014

Objectives : The purpose of this study was to investigate the effect of non-thermal atmospheric pressure plasma jet(NTAPPJ) on surface properties and Streptococcus mutans disinfection of denture base resin. Methods : Self-cured denture base resin (Jet denture repair resin, Lang dental Mfg, co., USA) was used to make specimen($12mm{\times}2mm$). To observe surface change before and after plasma process, surface roughness and contact angle were measured. For sterilization experiments, the surfaces of specimens were treated with nitrogen and air NTAPPJ for 1 minute after S. mutans was inoculated on the material surfaces. Results : Before plasma process, surface roughness of denture base resin was $0.21{\mu}m{\pm}0.02{\mu}m$. After air and nitrogen NTAPPJ process, surface roughness was $0.19{\mu}m{\pm}0.03{\mu}m$ and $0.18{\mu}m{\pm}0.01{\mu}m$ respectively. There was no significant difference(p>0.05). Contact angle of control group without plasma process was $83.81^{\circ}{\pm}3.14^{\circ}$, while after plasma treatment, contact angles of air NTAPPJ and nitrogen NTAPPJ groups were $63.29^{\circ}{\pm}2.27^{\circ}$ and $46.68^{\circ}{\pm}5.82^{\circ}$ respectively. The result showed a significant decrease in contact angle after plasma process(p<0.05). Compared to the control group 6020.33(CFU/mL) without plasma process, CFU decreased significantly after air NTAPPJ 90.75(CFU/mL) and nitrogen NTAPPJ 80.25(CFU/mL) treatment(p<0.05). Conclusions : It was considered that NTAPPJ can be used for denture disinfection without changing surface properties of materials.

• The Korean Journal of Physiology
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• v.4 no.1
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• pp.13-17
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• 1970

The changes in the red cell volume and the plasma chloride level were measured when the blood $CO_2$ content was altered by equilibration with the atmospheric air or pure $CO_2$ for 20 minutes. The red cell volume was expressed in terms of hematocrit and mean corpuscular volume (M.C.V.). The results obtained were as follows. 1) On equilibration with the atmospheric air, the MCV and the plasma chloride level were $91.6{\pm}1.26\;c.{\mu}$ and $110.7{\pm}6.28mEq/L.$ respectively. 2) On equilibration with pure $CO_{2}$, the MCV and the plasma chloride level were $109.6{\pm}2.0\;c.{\mu}$ and $90.7{\pm}5.17\;mEq/L.$ respectively. 3) When the blood was subjected to equilibration with the atmospheric for air 20 minutes after equilibration with pure $CO_{2}$ for the same period of time the MCV and the plasma chloride level were $89.9{\pm}6.34\;c.{\mu}$ and $100.3{\pm}5.50\;mEq/L.$ respectively. From the above results it can be concluded that an increase of the blood $CO_2$ content in the experimental condition causes definitely a decrease of the plasma chloride level and a concomitant increase of the red cell volume, and that a decrease of the blood content $CO_2$ in the experimental condition causes definitely an increase of the plasma chloride level and a concomitant decrease of the red cell volme. Apparantly there exists a parallel relationship between the extent of the decrease of the plasma chloride level and that of the increase of the red cell volume when the blood $CO_2$ content increased in the experimental condition. When the blood $CO_2$ content decreased, the extent of the decrease of the red cell volume exceeds that of the increase of the plasma chloride level.

• Journal of Adhesion and Interface
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• v.6 no.3
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• pp.1-9
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• 2005

This study investigated the influence of atmospheric plasma factors such as RF power, treatment time, the gap distance between discharge and sample, and the gas flow rate of Ar on the surface property by using the design of experiment (DOE) method. The plasma treatment time (s), plasma power (W), gap distance (mm) between discharge and sample, and flow rate of Ar gas were in order of important factors for changing the surface free energy of PMMA plates. As a result, the most effective factor for improving the surface free energy of PMMA plates is the distance (mm) from discharge glow to sample plate. Because of the interaction between plasma power (W) and treatment time (s), the power dose (J) factor which multiply plasma power (W) by treatment time (s) should be significantly considered. The optimum condition for maximizing the surface free energy of PMMA plate was found at 1500J of power dose. Through XPS and AFM analysis, we also observed the change of chemical composition, surface morphology and roughness before and after plasma treatment. It is considered that the change of surface free energy of PMMA plate with plasma treatment is influenced by the introduction of polar functional group as well as the increase of surface roughness.

• Journal of Industrial Convergence
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• v.21 no.3
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• pp.189-194
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• 2023

Recently, various studies on flexible electronic devices have been performed. In this study, the potential of Ag nanowires was evaluated as a material to replace the ITO transparent conductive film. Ag nanomaterials were formed on the glass by a novel brush coating method and an argon plasma evaporation method based on atmospheric pressure plasma. First, the Ag solution is coated on the glass with a brush, and the remaining solvent is removed with atmospheric plasma. During this process of solvent evaporation, a sound is generated by the reaction between the atmospheric plasma and the solvent. Therefore, the remaining amount of the solvent can be confirmed. In order to observe optical properties and electrical results such as reflectance, transmittance, and absorbance according to the number of coatings of the film, the results were analyzed by coating up to 5 times. For the purpose of investigating the interaction of light with Ag nanowires, reflectance and transmittance were measured while changing the wavelength of light from 200 nm to 800 nm. In the case of absorbance, the trend of increasing light absorption of the Ag nanowires according to the coating was clearly confirmed. The electrical properties showed a great change from the time of coating more than 4 times, and in particular, the resistance value was lower than kΩ/cm2 when the coating was applied 5 times. Based on these optical and electrical results, we plan to verify the possibility of a transparent conductive film by applying it to electronic devices in the future.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.85.1-85.1
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• 2015

We investigate the mass and energy of erupting plasma observed in X-rays and EUV, which is associated with a coronal mass ejection (CME) and an X-class flare. The erupting plasma was observed by both the X-ray telescope (XRT) on Hinode and the Atmospheric Imaging Assembly (AIA) on Solar Dynamic Observatory (SDO). We estimate the emission measures of the erupting plasma using a differential emission measure method. The plasma erupts with a loop-like structure in X-ray and EUV. We estimate the mass of erupting plasma assuming a cylinder structure. In addition, we estimate the radiative loss, thermal conduction, thermal, and kinetic energies of the eruptive hot plasma. We find that the thermal conduction timescale is much shorter than the duration of the eruption. This result implies that additional heating during the eruption may be required to explain the hot plasma observations in X-rays.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.162.1-162.1
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• 2015

The use of plasma has increased in bio-application field in recent years. Particularly, water treated by arc discharge or atmospheric pressure plasma has been actively utilized in bio-industry. In this study, we have developed a plasma activated water generating system. For this system, two kinds of plasma sources; dielectric barrier discharge (DBD) plasma and arc discharge plasma have been used. The discharge energy was calculated using the breakdown voltage and current, and the emission spectrum was measured to investigate the generated reactive species. We also analyzed the amount of reactive oxygen and nitrogen species in water using the chemical methods and nitric oxide sensor. Finally, the influence of plasma generated reactive species on the germination and growth of spinach (Spinacia oleracea) was investigated. Spinach is a green leafy vegetable that contains a large amount of various physiologically active organic compounds. However, it is characterized with a low seed germination rate.

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.117-138
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• 2006

Plasmas can be made by electrical discharge on earth. Most of the plasmas on earth have been generated in low pressure environments where the pressure is less than one millionth of the atmospheric pressure. However, there are many plasma applications which require high pressure plasmas. Therefore, scientists start research on plasma generation at high pressure to avoid use of expensive vacuum equipments. Large-volume inexpensive plasmas are needed in the areas of material processing, environmental protection and improvement, efficient energy source and applications, etc. We therefore developed new methods of plasma generations at high pressure and carried out research of applying these plasmas to high tech industries representing 21 century. These research fields will play pivotal roles in material, environmental and energy science and technology in future.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.3
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• pp.287-296
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• 2013

To decompose carbon dioxide, which is a representative greenhouse gas, a plasma torch was designed and manufactured. To examine the characteristics of carbon dioxide decomposition via plasma discharge, a case wherein pure carbon dioxide was supplied and a case wherein methane and/or $TiCl_4$ were injected as additives were investigated and compared. The carbon dioxide and methane conversion rate, energy decomposition efficiency, produced gas concentration, carbon monoxide and hydrogen selectivity, carbon-black and $TiO_2$ were also investigated. The maximum carbon dioxide conversion rate was 28.9% when pure carbon dioxide was supplied; 44.6% when $TiCl_4$ was injected as am additive; and 100% percent when methane was injected as an additive. Therefore, this could be explained that the methane injection showed the highest carbon dioxide decomposition. Furthermore, the carbon-black and $TiO_2$ were compared with each commercial materials through XRD and SEM. It was found that the carbon-black that was produced in this study is similar for commercial materials. It was found that the $TiO_2$ that was produced in this study is suitable for photocatalyst and pigment because it has mixed anataze and rutile.

• Journal of the Korean Ceramic Society
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• v.50 no.5
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• pp.326-332
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• 2013

In this study, we prepared yttria stabilized zirconia granules for thermal barrier coatings using a spray drying process. First, we characterized the properties of granules such as flow rate and packing density for utilizing the air plasma spray process. The flow rate and packing density data showed 0.732 g/sec and 2.14 $g/cm^3$, respectively, when we used larger and denser particles, which are better than hollow granules or smaller spherical granules. Second, we chose larger, spherical granules fabricated in alcohol solvent as starting powders and sprayed it on the bondcoat/nimonic alloy by an atmospheric plasma spray process varying the process parameters, the feeding rate, gun speed and spray distance. Finally, we evaluated representative thermal and mechanical characteristics. The thermal expansion coefficients of the coatings were $11{\sim}12.7{\times}10^{-6}/^{\circ}C$ and the indentation stress measured was 2.5 GPa at 0.15 of indentation strain.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.4
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• pp.379-386
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• 2011

Catalyst-assisted plasma system with a DBD (Dielectric Barrier Discharge) reactor was used to remove hydrogen sulfide, which is one of the odorous species in this study. The ${\gamma}-Al_2O_3$ and ${\beta}$-Zeolite catalysts impregnated by Ag, Cu and Mn species were employed as catalysts and their $H_2S$ removal characteristics under plasma irradiation were investigated. From the experimental study, we found that the $H_2S$ removal efficiency increases with decreasing space velocity in the system and increasing specific input energy. Furthermore, ${\beta}$-Zeolite catalysts are efficient to remove $H_2S$ than ${\gamma}-Al_2O_3$ catalysts. Especially, the catalysts impregnated by Ag have higher removal efficiency than other catalysts (Cu, Mn).