• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.11a
• /
• pp.216-220
• /
• 2006

In this study, it was investigated that the characteristics of startup and compatibility using several type hot and cold gases. The characteristics of starting LRE by pyro starter was compared with that by a He spinner. The compatibility of pyre gas, a gaseous He, H2+N2 mixture gas, and air was investigated by a simple 1D turbine analysis considered the properties of each gases and turbine efficiency. Most of them were compatible to start up the LRE but air was properly used only when the turbine was low power mode.

• Journal of the Korean institute of surface engineering
• /
• v.41 no.2
• /
• pp.43-47
• /
• 2008

Cubic boron nitride(c-BN) films were deposited on tungsten carbide insert tool by microwave plasma enhanced chemical vapor deposition(MPECVD) from a gas mixture of triethyl borate$(B(C_2H_5O)_3)$, ammonia $(NH_3)$, hydrogen$(H_2)$ and argon(Ar). The qualities of deposited thin film were investigated by x-ray diffrac-tion(XRD), field emission scanning electron microscopy(FE-SEM) and micro Raman spectroscope. The surface morphologies of the synthesised BN as well as crystallinity appear to be highly dependent on the flow rate of $B(C_2H_5O)_3$ and $(NH_3)$ gases. The deposited film had more crystallized phases with 5 scem of $B(C_2H_5O)_3$ and $(NH_3)$ gases than with 2 sccm, and the phase was identified as c-BN by micro Raman spectroscope and XRD. The adhesion strength were also increased with increasing flow rates of $B(C_2H_5O)_3$ and $(NH_3)$ gases.

• Economic and Environmental Geology
• /
• v.21 no.4
• /
• pp.381-387
• /
• 1988

Maewol Feldspar Mine produces feldspar ore from pegmatites. K-Rb Age of muscovite is 137.7Ma. Fluid inclusions in quartz crystal of the pegmatite show bimodal distribution of homogenization temperatures. The high homogenization temperatures range from 290 to $302^{\circ}C$ while low homogenization temperatures range from 157 to $195^{\circ}C$. Three phases liquid $CO_2$ bearing inclusions indicate $CO_2$ gases were abundantly mixed with granitic melt until the pegmatic magma melt cooled to $290^{\circ}C$. Low density of the magmatic melt relative to the same volume of granitic magma is due to mixture of volatiles(mainly $CO_2$ gases) with the melt and larger space and slow cooling allowed to grow crystals of the pegmatic magma.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.3C no.4
• /
• pp.136-139
• /
• 2003

The positive column of a discharge tube filled with a mixture of mercury-xenon has a tendency to become contracted at room temperature. However, once the tube temperature is raised over 50 [$^{\circ}C$], the positive column changes from a contracted state to a diffused state. The xenon emission is stronger in the contracted positive column than in the diffused column. Alternatively, the mercury emission is more intense in the diffused positive column, and the luminance of the phosphor coating on the inner surface of the tube is higher than that in the contracted positive column. Moreover, higher luminance can be obtained by increasing the xenon pressure.

• Journal of the Korean Chemical Society
• /
• v.17 no.5
• /
• pp.324-331
• /
• 1973

We study a mixture of ideal gases by use of recently developed methods in continuum thermodynamics of irreversible processes. A complete form of the free energy function and the gas law for each component are derived directly from an entropy production inequality by assuming that: (1) Constitutive functions depend on the mass densities, the diffusion velocities, the temperature and its gradient only. (2) Phenomenological coefficients appearing in an extra entropy flux are material constants. (3) The internal energy density per unit mass is independent of the total mass density (Joule).

• Journal of Mechanical Science and Technology
• /
• v.15 no.6
• /
• pp.752-763
• /
• 2001

Although there are many different solution schemes proposed for multidimensional radiative transfer, reference solutions to benchmark these methods are very rare in the literature. In this paper we produced some accurate solutions for purely absorbing gray and nongray gases including H$_2$O and CO$_2$by using the discrete transfer method with sufficiently accurate T(sub)95 quadrature set. The spectral transmittances of the mixtures of H$_2$O and CO$_2$are estimated by using the narrow band model. The gray gas solutions are obtained for different absorption coefficients, and the nongray real gas solutions are obtained for different mixture fractions of H$_2$O and CO$_2$. The numerical solutions presented in this paper are proved to be sufficiently accurate as compared to the available exact solutions and they may be used as reference solutions in evaluating various solution schemes.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
• /
• 2002.11a
• /
• pp.34-46
• /
• 2002

Si-O-C-H films with a low dielectric constant were deposited on a p-type Si(100) substrate using a mixture gases of the bis-trimethylsilyl-methane (BTMSM) and oxygen by an inductively coupled plasma chemical vapor deposition (ICPCYD). High density plasma of about $~10^{12}\textrm{cm}^{-3}$ is obtained at low pressure (<400 mTorr) with rf power of about 300W in ICPCVD where the BTMSM and $O_2$ gases are fully dissociated. Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS) spectra show that the film has $Si-CH_3$ and OH-related bonds. The void within films is formed due to $Si-CH_3$ and OH-related bonds after annealing at $500^{\circ}C$ for the as-deposition samples. The lowest relative dielectric constant of annealed film at $500^{\circ}C$ is about 2.1.

• Journal of the Semiconductor & Display Technology
• /
• v.19 no.2
• /
• pp.51-54
• /
• 2020

To develop gas-distinguishing sensor system, it is highly required to integrate multiple sensors for effective detection of a single targeted gas or mixture of gases. In addition, it is important to collect the reliable data from individual sensors into one integrated measuring device. Collecting the data of toxic gases on the spot should be done without inhalation. We suggest simple wirelessly running system for data collection that guarantees both reliability of data sources and safety. Here, we made a multi-gas measuring instrument(device) combined with Bluetooth module which provides a safe and precise big data accumulation system.

• Korean Journal of Materials Research
• /
• v.14 no.2
• /
• pp.157-162
• /
• 2004

The object of this research is to develop a carbon molecular sieve(below CMS) which can separate selectively to convert mixture gases spout at waste landfill into fuel. And this research is meaningful from the viewpoint of a quality improvement of CH$_4$ gas and an utilization of by-product. CMS was prepared using coconut shell powder as starting material and the effects of activators, temperature and modifier on the reaction were investigated in this research. Also, pore diameter, surface area of CMS and adsorption rate were measured and studied by cahn balance and ASAP2010. Its specific surface area and pore distribution were controlled easily at 800^{\circ}C and adsorption rate was very good. The CMS prepared in this research is shown to be able to separate landfill gases very effectively.

• Journal of Ceramic Processing Research
• /
• v.20 no.4
• /
• pp.388-394
• /
• 2019

In this study, high-purity single-walled carbon nanotubes (SWCNTs) were prepared by removing the unreacted metal constituents and amorphous carbon impurities using a post-annealing process. Unlike conventional thermal processing techniques, this technique involved different gas atmospheres for efficient removal of impurities. A heat treatment was conducted in the presence of chlorine, oxygen, and chlorine + oxygen gases. The nanotubes demonstrated the best characteristics, when the heat treatment was conducted in the presence of a mixture of chlorine and oxygen gases. The scanning electron microscopy, transmission electron microscopy, ultraviolet absorbance, and sheet resistance measurements showed that the heat treatment process efficiently removed the unreacted metal and amorphous carbon impurities from the as-synthesized SWCNTs. The high-purity SWCNTs exhibited improved electrical conductivities. Such high-purity SWCNTs can be used in various carbon composites for improving the sensitivity of gas sensors.