• Proceedings of the Materials Research Society of Korea Conference
• /
• 1998.11a
• /
• pp.15-15
• /
• 1998

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.516-520
• /
• 2009

Atmosphere Plasmas of Gas Discharge (APGD) have been used in plasma sources for material processing such as etching, deposition, surface modification, etc. This study is to investigate and understand the fundamental plasma discharge properties. Especially, $SF_6/N_2$ mixed gas would be used in power transformer, GIS (Gas insulated switchgear) and so on. In this paper, we developed a one dimensional fluid simulation model with capacitively coupled plasma chamber at the atmosphere pressure (760 [Torr]). 38 kinds of $SF_6/N_2$ plasma particles which are an electron, two positive ions (${SF_5}^+$, ${N_2}^+$), five negative ions (${SF_6}^-$, ${SF_5}^-$, ${SF_4}^-$, ${F_2}^-$, ${F_1}^-$), thirty excitation and vibrational particles for $N_2$ were considered in this computation. The $N_2$ gases of 20%, 50%, 80% were mixed in $SF_6$ gas. As the amount of $N_2$ gas was increased, the properties of electro-negative plasma moved toward the electro-positive plasma.

• Journal of the Korean Chemical Society
• /
• v.48 no.4
• /
• pp.339-350
• /
• 2004

The simplified cumulant method was applied to diffraction data of $CClF_3$ to study the equilibrium molecular parameters over a range of temperatures. The molecular parameters of $CClF_3$ by the simplified cumulant method were compared with those from the traditional method. Also the instrumentation of picosecond time resolved electron diffraction (TRED) and the experimental details are described. The total experimental temporal resolution was discussed in terms of the electron pulse width. The TRED system was applied to study the molecular structures for $CClF_3$ at room temperature. The molecular structural parameters $CClF_3$ from TRED are compared with those from GED/RT. The molecular parameters ($r_e$)of bonded C-F and C-Cl for $CClF_3$ by simplified CA are 132.00(2) pm and 175.20(3) pm, respectively, by using GED/RT. From the results of TRED experiments $r_a$ for bonded C-F and C-Cl are 132.23(13) pm and 177.23(19) pm.

• Journal of Photoscience
• /
• v.12 no.2
• /
• pp.101-107
• /
• 2005

Infrared multiphoton dissociation of $CHCl_2F$ was studied using $CO_2$ laser excitation. Three products, $C_2Cl_2F_2$, $C_2ClF_3$, and $C_2HClF_2$, were identified by the analysis of the gas mixture from the photoreaction of $CHCl_2F$. The dependence of the reaction probability on added Ar gas pressure and excitation laser pulse energy was investigated. At low pressure (< 10 torr), the reaction probability increased as Ar pressure increased due to the rotational hole-filling effect, while it diminished with the increase of Ar pressure at high pressure (> > 20 torr) due to the collisional deactivation. The ratio of two products $(C_2ClF_3/C_2Cl_2F_2)$ decreased at low pressure (< 10 torr) and increased at high pressure (> 20 torr) with the increase of Ar pressure. The log-log plot of the reaction probability vs. laser pulse energy (${\\phi}$) was found to have a linear relationship, and its slope decreased as the added Ar pressure was increased. The reaction mechanisms for product formation have been suggested and validated by experimental evidences and considering the energetics. Fluorine-chlorine exchange reaction in the intermediate complex has been suggested to explain the formation of $C_2ClF_3$.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1528-1530
• /
• 1997

As device size shrinks, contamination will increasingly affect the reliability and yield of device. Therefore, contaminants must be removed from the surfaces of Si wafers prior to each process. But it becomes out increasingly difficult to clean silicon surfaces with finer patterns by the conventional wet treatment because of the viscosity and surface tension of solutions. Hence, a damage less dry cleaning process is needed for the silicon surfaces. For the removal of Si native oxide by UV-enhanced dry cleaning. $F_2$ gas and $F_2/H_2$ mixed gas were applied. As a result of analysis, UV-enhnaced $F_2/H_2$ treatment is more suitable than UV-enhanced $F_2$ treatment for removal of native oxide on the surfaces of Si wafers.

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

• Journal of the Korean Ceramic Society
• /
• v.43 no.10 s.293
• /
• pp.595-600
• /
• 2006

The preparation of $\beta$-SiAlON powder by SHS in the system of $Si-Al-SiO_2-NH_4F(\beta-Si_3N_4)$ was investigated in this study. In the preparation of SiAlON powder, the effect of gas pressure, compositions such as Si, $NH_4F$, \beta-Si_3N_4$ and additive in mixture on the reactivity were investigated. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure $\beta$-SiAlON was $3Si+Al+2SiO_2+NH_4F$. The $\beta$-SiAlON powder synthesized in this condition was a single phase $\beta$-SiAlON with a rod like morphology.

• The Plant Pathology Journal
• /
• v.35 no.5
• /
• pp.437-444
• /
• 2019

Chlorine dioxide ($ClO_2$) has been widely used as an effective disinfectant to control fungal contamination during postharvest crop storage. In this study, Fusarium oxysporum f. sp. batatas SP-f6 from the black rot symptom of sweetpotato was isolated and identified using phylogenetic analysis of elongation factor 1-${\alpha}$ gene; we further examined the in vitro and in vivo inhibitory activities of $ClO_2$ gas against the fungus. In the in vitro medium tests, fungal population was significantly inhibited upon increasing the concentration and exposure time. In in vivo tests, spore suspensions were drop-inoculated onto sweetpotato slices, followed by treatment using various $ClO_2$ concentrations and treatment times to assess fungus-induced disease development in the slices. Lesion diameters decreased at the tested $ClO_2$ concentrations over time. When sweetpotato roots were dip-inoculated in spore suspensions prior to treatment with 20 and 40 ppm of $ClO_2$ for 0-60 min, fungal populations significantly decreased at the tested concentrations for 30-60 min. Taken together, these results showed that $ClO_2$ gas can effectively inhibit fungal growth and disease development caused by F. oxysporum f. sp. batatas on sweetpotato. Therefore, $ClO_2$ gas may be used as a sanitizer to control this fungus during postharvest storage of sweetpotato.

• Proceedings of the Optical Society of Korea Conference
• /
• 1990.02a
• /
• pp.3-8
• /
• 1990

방전여기 방식의 KrF 엑사이머 레이저의 컴퓨터 시뮬레이션 프로그램을 개발하여 방전중의 KrF 형성, 탈여기 및 흡수채널에서 완충가스의 영향을 이론적으로 해석하였다. 생성효율은 Ne 완충가스에서 He보다 2.2배 정도 높았으며, KrF의 탈여기는 He과 Ne 완충가스에서 각각 50%, 30% 정도의 비율을 차지하였다. 그러나 흡수 과정에서는 완충가스의 영향이 크지 않은 것을 알 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.10
• /
• pp.56-60
• /
• 2006

It is essential to predict thermodynamic properties of combustion gas with respect to a propellant mixture ratio for the development of a gas generator for a liquid rocket engine. The present study shows the temperature measurement of exit combustion gas as a function of a mixture ratio through the series of combustion tests of a fuel-rich gas generator with liquid oxygen and Jet A-1. The measurements of dynamic and static pressures, and combustion gas temperatures allowed the estimation of thermodynamic properties like a specific heat ratio, a gas constant, and a constant pressure specific heat of the combustion gas. The comparison of the experimental results with predictions made by interpolation parameters obtained from the modification of the chemical equilibrium code indicates that the interpolation method calibrated using the temperature measurements can be utilized as an effective tool for the initial design of a fuel-rich gas generator.