• Economic and Environmental Geology
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• v.32 no.1
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• pp.113-121
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• 1999

Coal is both source rock and reservoir rock for the coalbed gas. Coalbed gas. Coalbed gas is predominantly methane and has a heating value of approximatly 1000 BTU/$ft^3$. Most of methane is stored in the coal as a monomolecular layer adsorbed on the internal surface of the coal matrix. The amount of methane stored in coal is related to the rank and the depth of the coal. THe higher the coal rank and the deeper the coal seam is presently buried, the greater its capacity to hold gas. Most of Korean Coal is anthracite or metaanthracite, Ro. 3.5~5.5%, and total reserves are 1.6 billion metric tons. The domestic demand for coal was drastically decreased and the rationalization policy carried out from 1987 on coal industry. Now that a large number of coal mines was closed only a few mines continued to produce not more than 5 million tons for year. It is therefore recommended to formulate a strategy to explore and exploit the resources of coalbed methane in Korea.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.516-523
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• 2015

Nickel based oxygen transfer materials supported on two different YSZs were tested to evaluate their performance in methane chemical-looping reforming. The oxygen transfer materials of YSZs were selected with different amount of the doped yittrium in the $ZrO_2$ structure. The yittrium of 8 mol% stabilized the zirconia oxide to a cubic structure compare to the 3 mol% doping, which is known to be a good for oxygen transfer. Various nickel amounts (16wt.%, 32wt.%, 48wt.%) were loaded on the selected supports. The nickel amount of 32% shows the optimized catalyst structure with good physical properties and reducibility from the XRD, BET and H2-TPR analysis, especially when the support of 8YSZ was used. From the methane chemical-looping reforming, hydrogen was produced by methane decomposition catalyzed by Ni on both YSZs. Comparing two YSZ supports of 3YSZ and 8YSZ during the cycling tests, the catalyst with 8YSZ (Ni 32%) exhibits not only the higher methane conversion and hydrogen production but also a faster reaction rate reaching to the stable point.

• The Korean Journal of Petroleum Geology
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• v.7 no.1_2 s.8
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• pp.13-18
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• 1999

Methane hydrate is an ice-like solid material and it has a structure which water molecules enclose gas molecules. For low temperature and high pressure, hydrocarbon gas forms hydrate and due to this condition, it is existed in the arctic region or deep sea. Presently, the amount of methane hydrate is unpredictable, but it is assumed that the amount will be enormous. For this reason, it is expected that it will play a major role as natural gas resources in the future. However, the production technologies are stayed on the low level and the economical technology was not developed yet. Also, emission of natural gas from methane hydrate will cause global warming and thus it is considered as a critical environmental problem. In this paper, the state of the art of the production technologies and environmental effects of methane hydrate were summarized.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.769-775
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• 2011

Methane hydrate is formed by physical binding between water molecules and methane gas, which is captured in the cavities of water molecules under the specific temperature and pressure. $1m^3$ hydrate of pure methane can be decomposed to the methane gas of $172m^3$ and water of $0.8m^3$ at standard condition. Therefore, there are a lot of practical applications such as separation processes, natural gas storage transportation and carbon dioxide sequestration. For the industrial utilization of hydrate, it is very important to rapidly manufacture hydrate. So in this study, hydrate formation was experimented by adding THF and oxidized carbon nanotubes in distilled water, respectively. The results show that when the oxidized carbon nanofluids of 0.03 wt% was, the amount of gas consumed during the formation of methane hydrate was higher than that in the THF aqueous solution. Also, the oxidized carbon nanofluids decreased the hydrate formation time to a greater extent than the THF aqueous solution at the same subcooling temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1252-1257
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• 2011

Number of crop residues generated at large amount in agriculture can be utilized as substrate in methane production by anaerobic digestion. Greenhouse vegetable crop cultivation that adopting intensive agricultural system require the heating energy during winter season, meanwhile produce waste biomass source for the methane production. The purpose of this study was to investigate the methane production potential of greenhouse vegetable crop residues and to estimate material and energy yield in greenhouse system. Cucumber, tomato, and paprika as greenhouse vegetable crop were used in this study. Fallen fruit, leaf, and stem residues were collected at harvesting period from the farmhouses (Anseong, Gyeonggi, Korea) adopting an intensive greenhouse cultivation system. Also the amount of fallen vegetables and plant residues, and planting density of each vegetable crop were investigated. Chemical properties of vegetable waste biomass were determined, and theoretical methane potentials were calculated using Buswell's formula from the element analysis data. Also, BMP (Biochemical methane potential) assay was carried out for each vegetable waste biomass in mesophilic temperature ($38^{\circ}C$). Theoretical methane potential ($B_{th}$) and Ultimate methane potential ($B_u$) off stem, leaf, and fallen fruit in vegetable residues showed the range of $0.352{\sim}0.485Nm^3\;kg^{-1}VS_{added}$ and $0.136{\sim}0.354Nm^3\;kg^{-1}VS_{added}$ respectively. The biomass yields of residues of tomato, cucumber, and paprika were 28.3, 30.5, and $21.5Mg\;ha^{-1}$ respectively. The methane yields of tomato, cucumber, and paprika residues showed 645.0, 782.5, and $686.8Nm^3\;ha^{-1}$. Methane yield ($Nm^3\;ha^{-1}$) of crop residue may be highly influenced by biomass yield which is mainly affected by planting density.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.2
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• pp.95-102
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• 2000

Methane combustion over perovskite-type oxides prepared using the malic acid method was investigated. To enhance the catalytic activity, the perovskite oxides were modified by the substitution of metal into their A or B site. In addition, the reaction conditions, such as the temperature, space velocity, and partial pressure of the methane were varied to understand their effect on the catalytic performance. With the LaCoO3-type catalyst, the partial substitution of Sr or Ba into site A enhanced the catalytic activity in the methane combustion. With the LaBO3(B=Co, Fe, Mn, Cu)-type catalyst, the catalytic activities were exhibited in the order of Co>Fe Mn>Cu. Futhermore, the partial substitution of Co into site B enhanced the catalytic activity, whereas an excess amount of Co decreased the activity. The surface area and catalytic activity of the perovskite catalysts prepared using the malic acid method showed higher values than those prepared using the solid reaction method. The catalytic activity was enhanced with decreased methane concentration and with a decrease in the space velocity.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.791-793
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• 2009

Hydrogen has been recognized of the energy source for the future, in terms of the most environmentally acceptable energy source. A pressurized fluidized bed reactor made of carbon steel with 0.076 m I.D. and 1.0 m in height was employed for the thermocatalytic decomposition of methane to produce amount of $CO_2$ - free hydrogen with validity from a commercial point of view. The fluidized bed was proposed for withdrawing of product carbons from the reactor continuously. The methane decomposition rate with the carbon black N330 catalyst was rapidly reached a quasi-steady state and remained for several hour. The methane thermocatalytic decomposition reaction was carried out at the temperature range of 850 - 950 $^{\circ}C$, methane gas velocity of 2.0 $U_{mf}$ and the operating pressure of 1.0 -3.0 bar. Effect of operating parameters such as reaction temperature, pressure on the reaction rates was investigated and predicted the effect of a change in conditions on a chemical equilibrium thermodynamically, according to Le Chatelier's principle.

• Journal of the Korean Solar Energy Society
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• v.29 no.4
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• pp.34-40
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• 2009

$1m^3$ hydrate of pure methane can be decomposed to the maximum of $216m^3$ methane at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18-24% less than the liquefied transportation. In the present investigation, experiments and theoretical calculation carried out for the formation of methane hydrate in NaCl 3.5wt% solution. The results show that the equilibrium pressure in seawater is more higher than that in pure water, and methane hydrate could be formed rapidly during pressurization if the subcooling is maintained at 9K or above in seawater and 8K or above in pure water, respectively. Also, amount of consumed gas volume in pure water is more higher that in seawater at the same experimental conditions. Therefore, it is found that NaCl acts as a inhibitor.

• Animal Bioscience
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• v.34 no.1
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• pp.36-47
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• 2021

Objective: This study determined the optimal ratio of whole plant corn silage (WPCS) to corn stover (stems+leaves) silage (CSS) (WPCS:CSS) to reach the greatest profit of dairy farmers and evaluated its consequences with corn available for other purposes, enteric methane production and milk nitrogen efficiency (MNE) at varying milk production levels. Methods: An optimization model was developed. Chemical composition, rumen undegradable protein and metabolizable energy (ME) of WPCS and CSS from 4 cultivars were determined to provide data for the model. Results: At production levels of 0, 10, 20, and 30 kg milk/cow/d, the WPCS:CSS to maximize the profit of dairy farmers was 16:84, 22:78, 44:56, and 88:12, respectively, and the land area needed to grow corn plants was 4.5, 31.4, 33.4, and 30.3 ha, respectively. The amount of corn available (ton DM/ha/yr) for other purposes saved from this land area decreased with higher producing cows. However, compared with high producing cows (30 kg/d milk), more low producing cows (10 kg/d milk) and more land area to grow corn and soybeans was needed to produce the same total amount of milk. Extra land is available to grow corn for a higher milk production, leading to more corn available for other purposes. Increasing ME content of CSS decreased the land area needed, increased the profit of dairy farms and provided more corn available for other purposes. At the optimal WPCS:CSS, MNE and enteric methane production was greater, but methane production per kg milk was lower, for high producing cows. Conclusion: The WPCS:CSS to maximize the profit for dairy farms increases with decreased milk production levels. At a fixed total amount of milk being produced, high producing cows increase corn available for other purposes. At the optimal WPCS:CSS, methane emission intensity is smaller and MNE is greater for high producing cows.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.328-334
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• 2000

The hybrid catalytic(catalytic+thermal) combustor of a lean methane-air mixture on platinum catalyst was investigated numerically using a 2-D boundary layer model with detailed homogeneous and heterogeneous chemistries. For the more accurate calculations, the actual surface site density of monolith coated with platinum was decided by the comparison with experimental data. It was found that the homogeneous reactions in the monolith had little effect on the change of temperature profile, methane conversion rate and light off location. However, the radicals such as OH and CO were produced rapidly at exit by homogeneous reactions. Thus the homogeneous reactions were important to predict the productions of CO and NOx exactly. In thermal combustor, the production of $N_2O$ was more dominant than that of NO due to the relative important of the reaction $N_2+O(+M){\to}N_2O(+M)$. Finally the production of CO and NOx by amount of methane addition were studied.