• Journal of Korean Society for Atmospheric Environment
• /
• v.15 no.2
• /
• pp.183-190
• /
• 1999

Magnetite was synthesized with $FeSO_4$, and NaOH for the decomposition of carbon dioxide and for the study of the methane formation. The chemical equivalent ratio was changed from 0.5 to 1.50 for the magnetite synthesis. The chemical equivalent ratio was fixed in 1.00, and Nickel chloride and Rhodium chloride equally added and synthesized with the ratio was of 0.10~10.00 mole%. The crystal strucure of the synthesized magnetite was measured XRD. Putting synthesized magnetite in the reactor and using hydrogen gas oxygen-deficient magnetite was made. Injecting carbon dioxide in the reactor, the decomposition reaction was experimented. The formation of methane was confirmed injecting hydrogen gas in the reactor after carbon dioxide was decomposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.278-283
• /
• 2000

The activity of catalysts obtained by self-propagating high temperature synthesis in reaction of partial methane oxidation at atmospheric pressure was investigated. Basing on the compared results of X-ray analysis and gas chromatography analysis of reaction products, the dependence of compounds formation on the phase concentrations in the studied catalyst samples was found.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2005.11a
• /
• pp.160-161
• /
• 2005

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2008.10a
• /
• pp.471-472
• /
• 2008

• Journal of Korean Society for Atmospheric Environment
• /
• v.19 no.3
• /
• pp.275-284
• /
• 2003

The soil -air exchange processes of CH$_4$ were investigated in Hari district of Kang Hwa Island, Korea during the late April 2002. In the course of our field experiments, we measured the concentration, concentration gradients (between two different heights of 1 and 5 m), and the fluxes of CH$_4$ using the surface layer gradient microm-eteorological methods. If the relationships between CH$_4$ fluxes and the relevant environmental parameters are examined, CH$_4$ fluxes were found to be affected most significantly by parameters like wind speed. The results of our study indicate that the study area behaved as a net source of CH$_4$ to the atmosphere with a net daily emission rate of 3.6 mg m￣$^2$ The findings of relatively low exchange rate observed at our study site suggest that the rice paddy area investigated prior to planting period can behave as a moderate source of methane.

• Journal of the Korean Wood Science and Technology
• /
• v.17 no.2
• /
• pp.13-19
• /
• 1989

Two different quartz types of gasification reactor were used for pyrolysis and gasification of sawdust, ricestraw, ricehusk and municipal wastes which contain only cellulosics., operating at 1 atmospheric and vacuum pressure respectively. Also a stainless steel autoclave gasification reactor was used which is possible to use up to 100 atmospheric pressures and $800^{\circ}C$ of reaction temperature to complete pyrolysis and gasification reaction. The catalysts used in this reaction w- ere $K_2CO_3$, $Na_2CO_3$, Ni and Ni-$K_2CO_3$ as CO-Catalyst. The product gas mixtures were identified to be CO, $CO_2$, $C_3H_3$, $CH_4$ and $CH_3CHO$ etc. by Gas Chromatography and Mass Spectrometry. The pressurized gasification reaction shows significant increase in terms of methane composition and yield of product gases, comparing with those from unpressurized gasification reactions. The total volume of product gas mixtures amounts to 1600-1800ml per1gof waste of waste lignocellulosics or municipal waste, and the metane content of the gas mixtures reached to 40%, when $800^{\circ}C$ of reaction temperature and 100 atmospheric pressures with Ni-$K_2CO_3$ as CO-catalyst in the pressurized gasification reaction were used. This results show that the product gas mixtures containing 40% of methane call be used for alternative enegy source.

• Journal of the Korean institute of surface engineering
• /
• v.36 no.5
• /
• pp.357-363
• /
• 2003

The aim of this work is the synthesis of a-C:H films from methane gas using surface spark discharge at the atmospheric pressure. Properties of these films have been investigated as functions of energy W delivered per a methane molecule in the discharge. The method enables the coatings to be deposited with high growth rates (up to $100 \mu\textrm{m}$/hour) onto large-area substrates. It is shown that the films consist of spherical granules with diameter of 20∼50 nm formed in the spark channel and then deposited onto the substrate. The best film characteristics such as minimum hydrogen-to-carbon atoms ratio H/C=0.69, maximum hardness $H_{v}$ =3 ㎬, the most dense packing of the granules and highest scratch resistance has been obtained under the condition of highest energy W of 40 eV. The deposited a-C:H coatings were found to be more soft and hydrogenated compared to the diamond-like hydrogenated (a-C:H) films which obtained by traditional plasmaenhanced chemical vapor deposition methods at low pressure (＜10 Torr). Nevertheless, these coatings can be potentially used for scratch protection of soft plastic materials since they are of an order harder than plastics but still transparent (the absorption coefficient is about $10^4$∼$10^{5}$ $m^{-1}$ At the same time the proposed method for fast deposition of a-C:H films makes this process less expensive compared to the conventional techniques. This advantage can widen the application field of. these films substantially.y.

• International Journal of Advanced Culture Technology
• /
• v.3 no.2
• /
• pp.110-117
• /
• 2015

10 wt% (Ni-Co) catalysts with different Ni and Co content : 10%Ni, 9%Ni1%Co, 7%Ni3%Co, 5%Ni5%Co, 3%Ni7%Co, and 10%Co; were prepared using sol-gel method followed by incipient wetness impregnation method. To investigate the catalytic activity including the stability, dry methane reforming were demonstrated over the pelletized catalysts at $620^{\circ}C$ under atmospheric pressure in a $CH_4:CO_2:N_2$ feedstock for 360 min. The results showed that bimetallic catalysts with the Co content equal to or greater than 3% were more stable than monometallic catalysts (10%Ni and 10%Co). The temperature programmed hydrogenation interpreted that the additional of Co into Ni catalyst improved the carbon resistance from methane cracking. Promoted this type of bimetallic catalyst using 1wt% K (trimetallic catalyst) prevented the carbon formation on the catalyst. The temperature programmed desorption of $CO_2$ indicated that this trimetallic catalyst has a greater number of strong basic sites. Moreover, the appearance of K lowered the number of weak basic sites and decreased the conversion of methane by 12 %.

• The Korean Journal of Quaternary Research
• /
• v.18 no.2 s.23
• /
• pp.23-31
• /
• 2004

Temperature variations, and carbon dioxide and methane concentrations are summarized during the past 400,000 years. Atmospheric temperature varied approximately within $10^{\circ}C$ during the past 400,000 years. Most of the time during the past 400,000 years, temperature was lower than today except 410000, 320000, 250000, and 125000 years ago. Temperature was slightly higher or at least similar to today during the time period of 410000. 320000, 250000, and 125000 years ago. The carbon dioxide concentration varied between 180 and 300 ppm, and the methane concentration varied between 40 and 700ppb. The present atmospheric concentration of carbon dioxide is 375 ppm and methane is 1750 ppb. Temperature was 5-$7^{\circ}C$ lower than today during the Last Glacial Maximum(18,000 years ago) and the Younger Dryas(10,000 years ago). Temprature was varied within $1^{\circ}C$ during the past 10,000 years. Especially Middle Holocene Climatic Optimum(6,000 years ago), Medieval Warm Period (500-1,000 years ago), and Little Ice Age(100-500 year ago) were global climatic events. In general, mechanism for the Middle Holocene Climatic Optimum, Medical Warm Period, and Little Ice Age can be explained by the solar insulation, however their exact mechnism is not well known. Carbon dioxide concentration during the past 400,000 years never reached the current value of 375 ppm. Furthermore, the current methane concentration never reached during the past 20Ma. However, current temperature value has happened several times during the past 400,000 years. The implication of this is unsolved question so far. This should be challenged in the near future.

• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.5
• /
• pp.712-718
• /
• 2006

In order to investigate the analytical uncertainties associated with sampling and analysis of major greenhouse gaseous pollutants(carbon dioxide and methane), we attempted to quantify their adsorptive loss due to the contact with the container wall(such as Tedlar bag and vial). Using the GC/FID method, some basic experimental parameters(such as reproducibility and method detection limit) have been evaluated as part of the essential QA/QC The reproducibilities of carbon dioxide and methane were estimated as 2.02 and 0.2%, respectively. In addition, method detection limits were measured as 0.61 and 0.06 ng, respectively. A test of sample loss rate has also been made for Tedlar bag and vial by assessing the absolute amount of sample loss on the wall. By transferring the samples contained in Tedlar bag to various sizes of Tedlar bags, we measured differences in the absolute loss quantity due to such transfer. In addition, we also examined such loss mechanism as a function of elapsed time and light penetration rate for vial. As results, carbon dioxide and methane have shown about 2% of sample loss due to such contact. It is also noticed that the amount of loss with vial surface is lower than that of Tedlar bag. Therefore, field collection of greenhouse gases using various container types should be made more cautiously to minimize the possibility of sample loss and bias related to such loss.