• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.317-321
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• 2014

This paper describes the information for quantitative simulation of weakly ionized plasma. We must grasp the meaning of the plasma state condition to utilize engineering application and to understand materials of plasma state. Using quantitative simulations of weakly ionized plasma, we can analyze gas characteristic. In this paper, the electron Ionization and diffusion Coefficients in $CH_4$ has been analysed over the E/N range 0.1~300[Td], at the 300[$^{\circ}K$] by the two term approximation Boltzmann equation method and Monte Carlo Simulation. Boltzmann equation method has also been used to predict swarm parameter using the same cross sections as input. The behavior of electron has been calculated to give swarm parameter for the electron energy distribution function has been analysed in $CH_4$ at E/N=10, 100 for a case of the equilibrium region in the mean energy. A set of electron collision cross section has been assembled and used in Monte Carlo simulation to predict values of swarm parameters. The result of Boltzmann equation and Monte Carlo Simulation has been compared with experimental data by Ohmori, Lucas and Carter. The swarm parameter from the swarm study are expected to sever as a critical test of current theories of low energy scattering by atoms and molecules.

• Membrane Journal
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• v.4 no.4
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• pp.205-212
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• 1994

Gas permeation properties of simple gases(He, $H_2,\;CO_2,\;O_2,\;N_2,\;CH_4$) through plasma-polymerized films were investigated, and the chemical structure of the plasma polymers was analyzed by infrared spectra. The plasma-polymerized films were prepared by plasma polymerization of fluorine-containing aromatic compounds, and permeation measurements were made at $35^{\circ}C$, latm. The permeability coefficient of the plasma films decreased as the size of penetrant molecules increased. The plasma polymers showed higher $CO_2/CH_4$ selectivities than those of commonly used polymers, while $O_2/N_2$ selectivities were similar of slightly lower than those of common polymers. FT-IR spectra shows that the plasma polymers contain both aromatic and aliphatic structures.

• Fire Science and Engineering
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• v.15 no.3
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• pp.44-48
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• 2001

In this study, we analyzed the $CH_4$and $C_4$$H_{10}$ sensitivity measurement and voltage variation using catalytic type gas sensor characteristics in catalytic combustion type gas detecter sensors. Gas detector shall operate as intended when exposed for 24 hours to air having a relative humidity of 65 percent at a temperature of $20^{\circ}c$ and humidity of 85 percent at a temperature of $40^{\circ}c$. The gas detecter sensors are to be subjected to operation for 210 days in an area that has been determined to be equivalent to a typical residential atmosphere with an air velocity of 50 cm/sec. The source of energy for a gas detector sensors employing a supplementary basic circuit is energized from a seperate source of supply direct applied voltage 2.1V, 2.2V, 2.3V. As a result, it was confirmed that the relative humidity and temperature by regression each analysis, compared to the isobutane characteristic graph and methane characteristic graph by a relative humidity of 65% and 85% at a temperature($20^{\circ}c$, $40^{\circ}c$) show a similar linear pattern on the whore.

• Journal of the Korean GEO-environmental Society
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• v.6 no.4
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• pp.27-35
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• 2005

A case study of the assessment for environmental stabilization in open dumping landfill site was carried out physical composition, total solid, moisture, and landfill gas(LFG) analysis in landfill site. The result of physical ratio were represented combustibles 23.64% and incombustibles 76.36%, TS 77.69%, VS 74.24%, FS 25.75%. The biodegradable organic matters were almost degraded and the result of the landfill gas showed that the $CH_4$ gas were measured as 4.5%. As the result of the assessment on the open dumping landfill it appears that this landfill is stabled for the maturation phase and formation $CO_2$ concentration lower than 15%.

• Clean Technology
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• v.16 no.3
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• pp.198-205
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• 2010

Two sets of thermal reaction experiment for chlorinated hydrocarbons were performed using an isothermal tubular-flow reactor in order to investigate thermal decomposition, including product distribution of chlorinated hydrocarbons. The effects of $H_2$ or Ar as the reaction atmosphere on the thermal decomposition and product distribution for dichloromethane($CH_2Cl_2$) was examined. The experimental results showed that higher conversion of $CH_2Cl_2$ was obtained under $H_2$ atmosphere than under Ar atmosphere. This phenomenon indicates that reactive-gas $H_2$ reaction atmosphere was found to accelerate $CH_2Cl_2$ decomposition. The $H_2$ plays a key role in acceleration of $CH_2Cl_2$ decomposition and formation of dechlorinated light hydrocarbons, while reducing PAH and soot formation through hydrodechlorination process. It was also observed that $CH_3Cl,\;CH_4,\;C_2H_6,\;C_2H_4$ and HCl in $CH_2Cl_2/H_2$ reaction system were the major products with some minor products including chloroethylenes. The $CH_2Cl_2$/Ar reaction system gives poor carbon material balance above reaction temperature of $750^{\circ}C$. Chloroethylenes and soot were found to be the major products and small amounts of $CH_3Cl$ and $C_2H_2$ were formed above $750^{\circ}C$ in $CH_2Cl_2$/Ar. The thermal decomposition reactions of chloroform($CHCl_3$) with argon reaction atmosphere in the absence or the presence of $CH_4$ were carried out using the same tubular flow reactor. The slower $CH_3Cl$ decay occurred when $CH_4$ was added to $CH_3Cl$/Ar reaction system. This is because :$CCl_2$ diradicals that had been produced from $CHCl_3$ unimolecular dissociation reacted with $CH_4$. It appears that the added $CH_4$ worked as the :$CCl_2$ scavenger in the $CHCl_3$ decomposition process. The product distributions for $CHCl_3$ pyrolysis under argon bath gas were distinctly different for the two cases: one with $CH_4$ and the other without $CH_4$. The important pyrolytic reaction pathways to describe the important features of reagent decay and intermediate product distributions, based upon thermochemistry and kinetic principles, were proposed in this study.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.281-286
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• 2011

The objective of this study is to optimize the four-bed six-step pressure swing adsorption(PSA) process for high purity $CH_4$ recovery from the biogas. The effects of P/F(purge to feed) ratio and cycle time on the process performance were evaluated. The cyclic steady-states of PSA process were reached after 12 cycles. The purity and recovery rate of product gas, pressure and temperature changes were constant as the cycle repeated. It was shown that the P/F ratio gave significant effect on the product recovery rate by increasing the amount of purge gas in purge and regeneration step. The optimal P/F ratio was found to be 0.08. As the cycle time increased, the product purity decreased by increasing the feed gas flow rate. It was found that the optimal operating conditions were P/F ratio of 0.08 and total cycle time of 1,440 seconds with the purity of 97%.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.3
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• pp.13-18
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• 1999

Diamond film was deposited on Si wafer using $\textrm{H}_2$ and $\textrm{CH}_4$ mixed gas by RF PACVD. Prior to deposition, mechanical scratching was done to improve density of nucleation sites with diamond paste of $1\mu\textrm{m}$ The microstructure of deposited film was studied at various methane concentrations. The deposited film was characterized by XRD(X-tay diffraction), SEM(Scanning Electron Microscopy) and Raman Spectroscopy The deposited diamond film showed that the crystallite was increased at the lower methane concentration.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.11
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• pp.596-602
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• 2000

Diamond thin films were synthesized on WC-Co substrate at various experimental parameters using 13.56MHz RF PACVD)radio frequency plasma-assisted chemical vapor deposition). In order to increased the nucleation density, the WC-Co substrate was polished with 3${\mu}m$ diamond paste. And the WC-Co substrate was preatreated in $HNO_3\;:\;H_2O$ = 1:1 and $O_2$ plasma. In $H_2-CH_4$ gas mixture, the crystallinity of thin film increased with decreasing $CH_4$ concentration at 800W discharge power and 20torr reaction pressure. In $H_2-CH_4-O_2$ gas mixture, the crystallinity of thin film increased with increasing $O_2$ concentration at 800W discharge power, 200torr reaction pressure and 4% $CH_4$ concentration.

• Journal of Hydrogen and New Energy
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• v.26 no.5
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• pp.402-408
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• 2015

In D-T fusion reaction, $D_2$ (duterium) and $T_2$(tritium) are used as fuel gas. The exhaust gas of nuclear fusion includes hydrogen isotopes $Q_2$ (Q means H, D or T), tritiated components ($CQ_4$ and $Q_2O$), CO, $CO_2$, etc. All of hydrogen isotopes should be recovered before released to the atmosphere. This study focused on the recovery of hydrogen isotopes from $CQ_4$ and $Q_2O$. Two kinds of experiments were conducted to investigate the catalytic reaction characteristics of SMR (Steam Methane Reforming) and WGS (Water Gas Shift) reactions using Pt catalyst. First test was performed to convert $CH_4$ into $H_2$ using 6% $CH_4$, 6% CO/Ar feed gas. In the other test, 100% CO gas was used to convert $H_2O$ into $H_2$ at various reaction conditions (reaction temperature, S/C ratio, GHSV). As a result of the first test, $CH_4$ and CO conversion were 41.6%, 57.8% respectively at $600^{\circ}C$, S/C ratio 3, GHSV $2000hr^{-1}$. And CO conversion was 72% at $400^{\circ}C$, S/C ratio 0.95, GHSV $333hr^{-1}$ in the second test.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.