• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.223-228
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• 1997

The gas dynamics in a stagnation point upflow OMVPE reactor were studied by Raman spectroscopy. The gas temperature was measured as a function of inlet gas velocity and aspect ratio for both H$_2$ and N$_2$ carrier gases. The centerline temperature gradient was latger at higher inlet velocities and with the use of N$_2$, and only weakly dependent on the aspect ratio. a tracer molecule, CH$_4$, was used to investigate the steady state behavior of reactants in the reactor, and the use of a sweeping flow was found to be a suitable method for preventing wall deposition. The transient switching response of the gas manifold was also investigated. Under certain conditions (low velocities, unmatched flows) recirculation flows were apparent. Numerical calculations of the reactor gas dynamics gave reasonable agreement with experimental results when detailed thermal boundary conditions were included.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.427-430
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• 2002

Plasma nitrocarburizing treatment was performed for SCM 435 steel by using a plasma ion nitriding system. The effects of the variation of nitrogen and methan contents upon the hardened layer was investigated. Both the thickness of the compound layer and the amount of $\varepsilon$ phase in the compound layer increased with increasing nitrogen content. However, the thickness of the compound layer decreased due to unstable plasma for an atmosphere containing 90% $N_2$ gas content in the gas mixture. The amount of $\varepsilon$phase in the compound layer increased with increasing $CH_4$ gas content. For $CH_4$ gas content more than 2% in the gas mixture, the thickness of the compound layer decreased due to the formation of $\theta$ phase.

• Journal of the Korean institute of surface engineering
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• v.44 no.2
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• pp.60-67
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• 2011

Ternary B-C-N coatings were deposited on Si(100) wafer substrate from $B_4C$ target by RF magnetron sputtering technique in $Ar+N_2+CH_4$ gas mixture. In this work, the effect of reactant gas ratio, $CH_4/(N_2+CH_4)$ on the composition, kinds and amounts of bonding states comprising B-C-N coatings were investigated using two different bias power sources of continuous and unipolar DCs. In addition, the tribological properties of coatings were studied with the composition and bonding state of coating. It was found that the substrate bias power had an effect on chemical composition, and all of the obtained coatings were nearly amorphous. Main bonding states of coatings were revealed from FTIR analyses to be h-BN, C-C, C-N, and B-C. The amount of C-C bonging mainly increased with increase of the reactant gas ratio. From our studies, both C-C and h-BN bonding states improved the tribological properties but B-C one was found to be harmful on those. The best coating from tribological points of view was found to be $BC_{1.9}N_{2.3}$ composition.

• Membrane Journal
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• v.32 no.5
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• pp.325-335
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• 2022

In this study, zeolitic imidazolate framework-9 (ZIF-9) was synthesized and Pebax/ZIF-9 mixed membranes were prepared by varying the content in poly(ether-b-amide)-1657 (Pebax-1657), and then a single gas (N₂, CO₂) was permeated to investigate the gas permeation characteristics of the mixed membrane. As the ZIF-9 content incorporated into the pure Pebax membrane increased, the N₂ permeability gradually decreased, and the CO₂ permeability increased up to the Pebax/ZIF-9 3 wt% mixed membrane, and then decreased at the content thereafter. And among the mixed membranes, the Pebax/ZIF-9 3 wt% mixed membrane showed the highest selectivity of 69.3 by selectively accepting CO₂ as the gate-opening phenomenon occurred for the polar gas, CO₂. In addition, both the CO₂ permeability and the CO₂/N₂ selectivity increased, resulting in the closest Robeson upper-bound.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.105-108
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• 1998

Pt-WO$_3$-Si$_3$N$_4$-SiO$_2$-Si-Al 캐패시터를 이용한 NO$_2$ 가스 센서를 개발하였다. 표준 실리콘 MNOS구조에 촉매 게이트로 Pt와 가스 흡착층으로 WO$_3$를 이용함으로서 전통적인 세라믹 가스 센서보다 낮은 온도에서 NO$_2$ 가스를 감지할 수 있었다. 은도 변화와 NO$_2$ 가스 농도의 변화에 따라서 디바이스의 NO$_2$ 가스 감도를 조사하였다. Pt-WO$_3$ 계면에서 NO$_2$ 이온농도의 변화에 기초로 한 가스 감지 모델을 제시하였다. 제시된 가스 감지 모델을 계면에서의 가스 반응 속도론에 의하여 분석함으로서 확인하였다.

• Membrane Journal
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• v.22 no.1
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• pp.72-76
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• 2012

$SF_6$ has an extremely high global worming potential (GWP). Therefore, there has been an effort to reduce the use of $SF_6$ and its emission into atmosphere. One possible solution for minimizing the use of $SF_6$ in electrical equipments is utilization of gas mixtures such as $SF_6/N_2$. The $SF_6$ concentration in the gas mixture varies from 10 to 60%. However, when the apparatus is repaired or dismantled, we have to recover $SF_6$ from the gas mixture. Since the boiling point of $SF_6$is low (${\sim}-60^{\circ}C$), the liquefaction method is difficult to apply. One possible alternative is the membrane separation technology. In this study, we investigated the $SF_6$ and $N_2$ permeation properties of 5 polymeric membranes. For example, permeability of $N_2$ in BOPP membrane at $25^{\circ}C$was 0.19 barrer, whereas that of $SF_6$ was only 0.0012 barrer, resulting in the selectivity of 158. An upper bound for $SF_6/N_2$ gas pair was suggested for the first time with n = -1.33 and k = 160 (barrer).

• 전기의세계
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• v.30 no.5
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• pp.306-312
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• 1981

The Townsend discharge domain is generally observed with stable positive characteristics in N$_{2}$ gas discharge at low pressures differently in the others, which transfer immediately to glow dischage after self-sustaining discharge starts. In this paper, the presence of the stable Townsend discharge, applied voltage-discharge current characteristics and the effect of disgased electrode surface on stable townsend discharge are studied experimentaly in N$_{2}$ gas mixed with 0.05% of No in volume. As the result of this experiment, the stable Townssend discharge is observed only in pure nitrogen with the valve of pd.geq.8[torr.cm] (p=gas pressure, d=gap spacing), but not in gas mixtures. This is considered that No gas in gas mixtures disexcites effectively the metestble state of nitrogen.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.489-489
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• 2012

The vibrational distribution of $N_2$ (B, v') in after-glows in $N_2$ RF flowing plasma was investigated. The optical emission of the after-glow was studied as function of distance from plasma. In a tube 2.1 cm, the gas pressure varied 8 Torr with 1000sccm nitrogen gas flowing late.. The discharges were excited by two ring-electrode powered by RF 13.56 MHz 100 Watt. $N_2$ (B, v') vibrational distribution was analyzed to see depends of position in after-glow. Dissociation rate of $N_2$ varied showing maximum in the late after-glow region. We studied $N_2$ RF capacitive flowing plasmas and afterglows by emission spectroscopy and by NO titration to determine the density of N-atoms.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.6
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• pp.562-570
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• 2009

Although anthracite power plant acts as the important source of greenhouse gas emissions, relatively little is known about its emission potentials. Especially, because the emissions of Non-$CO_2$ greenhouse gas $CH_4$ and $N_2O$ are strongly dependent on fuel type and technology available, it is desirable to obtain the information concerning their emission pattens. In this study, the anthracite power plants in Korea were investigated and the emission gases were analyzed using GC/FID and GC/ECD to develop Non-$CO_2$ emission factors. The anthracite samples were also analyzed to quantity the amount of carbon and hydrogen using an element analyzer, while calorie was measured by an automatic calorie analyzer. The emission factor of $CH_4$ and $N_2O$ computed through the gas analysis corresponded to 0.73 and 1.98 kg/TJ, respectively. Compared with IPCC values, the $CH_4$ emission factor in this study was about 25% lower, while that of $N_2O$ was higher by about 40%. More research is needed to extend our database for emission factors of various energy-consuming facilities in order to stand on a higher position.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.37-42
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• 1997

This paper describes result of experiment of parameters affecting the micro hole drilling time, kind of assisting gas and it's pressure. The result reveals that parameter value of 0.08J, 20Hz, dwell time of 300 microseconds can be a good machining condition to make micro hole diameter range of 50-70${\mu}{\textrm}{m}$, Assistant gas such air, O2, Ar, N2 was adapted. Assistant gas of air makes heat affected zone enlarge due to burning of material, also it makes hole irregular and damage because of refusion stick to caused by chemical reaction with Al2O3 ceramic material. O2(99.9%) has good characteristic to get good drilling and smooth surface on pressure of 0.2kgf/$\textrm{cm}^2$, but it is expensive. Ar, N2 makes material burn and crack severely and proved to be an appropriate but, Ar was better than N2.