• Journal of Plant Biotechnology
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• v.34 no.2
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• pp.103-109
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• 2007

The increasing industrialization of the world has led to precipitous rise for the demand of petroleum-based fuels. The world is presently confronted with the twin crises of fossil fuel depletion and environmental pollution. The search for alternative fuels, which promise a harmonious correlation with sustainable development, energy conservation, efficiency and environmental preservation, has become highly pronounced in the present. Bioenergy is playing an increasingly important role as an alternative and renewable source of energy. Use of Bioenergy has several potential environmental advantages. The most important perhaps is reduction in life cycle greenhouse gases emissions relatives petroleum fuels, since bioenergy is derived from plants which convert Carbon dioxide ($CO_{2}$) into Carbohydrates in their growth. Bioenergy includes solid biomass, biomas and liquid bio-fuels which are fuels derived from crop plants, and include biomass that's directly burned. The two most important bio liquid fuels today are bioethanol from fermenting grain, grass, straw or wood, and biodiesel from plant seed oil.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.2
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• pp.150-157
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• 2004

Carbon dioxide ($CO_2$, R-744) has become a very popular issue in application to refrigeration and air conditioning systems as a natural refrigerant. An experimental study has been carried out to investigate miscibility and the vapor pressure of refrigerant R-744 in the presence of lubricant oil. This is of particular interest in the selection of the lubricant oil for the compressor of a refrigeration system or an air conditioning system using the refrigerant R-744. The experimental set-up consists of the equilibrium cell, measuring devices, the vacuum pump, the constant temperature bath and relevant connecting pipes made of stainless steel. Five lubricant oils, such as mineral oil (Naphthenic), AB (Alkyl Benzene) oil, PAO (Poly Alpha Olefin) oil, PAG (Poly Alkylene Glycol) oil and POE (Polyol Ester) oil are considered in the present study. Test runs were conducted with the oil concentration range from 5 to 50 wt％, and the temperature range from -10 to 1$0^{\circ}C$ with 2$^{\circ}C$ intervals. The miscibility results are visualized and correlated with the vapor pressure for the individual test components.

• Journal of the Semiconductor & Display Technology
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• v.13 no.3
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• pp.35-38
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• 2014

Flat panel displays fabricated on glass substrate use amorphous Si for data processing circuit. Recent progress in display technology requires a new material to replace the amorphous Si, and ZnO is a good candidate. ZnO is a wide bandgap (3.3 eV) semiconductor with high mobility and good optical transparency. ZnO is usually grown by sputtering using ZnO ceramic target. However, ceramic target is more expensive than metal target, and making large area target is very difficult. In this work we studied characteristics of ZnO thin-film transistor grown by rf sputtering using Zn metal target and $CO_2$. ZnO film was grown at $450^{\circ}C$ substrate temperature, with -70 V substrate bias voltage applied. By using these methods, our ZnO TFT showed $5.2cm^2/Vsec$ mobility, $3{\times}10^6$ on-off ratio, and -7 V threshold voltage.

• New & Renewable Energy
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• v.6 no.1
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• pp.29-37
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• 2010

Biogas is a carbon neutral energy and consists of mostly methane and carbon dioxide, with smaller amounts of water vapor, and trace amounts of $H_2S$, Siloxane and other impurities. Hydrogen sulfide and Siloxane usually must be removed before the gas can be used for generation of electricity or heat. The goals of this project are to develope the Fuel conditioning system of Land Fill Gas for 30kW-Micro Gas Turbine co-generation system. The fuel conditioning system mainly consists of $H_2S$ removal system, Land Fill Gas compressor, Siloxane removal system and many filtering systems. The fuel requirement of 30kW MGT is at least 32% of $CH_4$, $H_2S$ (<30 ppm), Siloxane (<5ppb) and supply pressure (> 0.6 MPa) from LFG compressor. Main mechnical charateristics of Micro Gas Turbine system by using LFG have the specific performance; 1) high speed turbine speed (96,000 rpm) 2) very clean emmission NOx (<9 ppm) 3) high efficiency of energy conversion rate. This paper focuses on the development of design technology for LFG fuel conditioning system. The study also has the plan to replace the fuel of gas turbine and other distributed power systems. As the increase of Land Fill Gas (LFG), this system help to contribute to spread more New & Renewable Energy and the establishment of Renewable Portfolio Standards (RPS) for Korea.

• Clean Technology
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• v.16 no.4
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• pp.239-244
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• 2010

The carboxylation of the fluorenyl epoxide with a spiro framework, 9,9'-Bis(4-oxiranylmethoxyphenyl) fluorine (2) was catalyzed by some onium salts such as quaternary ammonium and phosphonium salts to produce the corresponding five-membered cyclic carbonate (3) in an efficient and environmentally benign fashion. The coupling reactions depend greatly on the kind of the halide anions and alkyl chain length of the onium salts. While the reaction was sensitive to the reaction temperature, the reaction trends suggest that the catalytic efficiency of the quaternary ammonium halides may correlate strongly with the melting points of the halides. The reactions using a catalytic amount (2 mol %) of quaternary ammonium bromide with an n-butyl chain at 75.9 bar of $CO_2$ and 393 K give the highest yield of the cyclic carbonate (92%).

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.157-164
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• 1969

Aoolphane was treated with 30% Hydrochloric acid at $18^{\circ}C$ for two hows with stirring in order to obtain the insoluble form of SiO2 gel and to extract quantitatively both $Al_2O_3$as and $Fe_2O_3AlCl_3{\cdot}6H_2O Fe$ and $Cl_3{\cdot}6H_2O$ forms, respectively, at the same time. $SiO_2$ gel was filtered and to the filterate Ammonia was added to precipitate $Al(OH)_3[Fe(OH)_3 Contaminated ]$ The precipitate was separated by filteration and the filterate was recovered as the form of $NH_4Cl$. The precipitate was treated with 200g (NaOH)/l Concentration of NaOH a little excessively to the equivalent at $65~70^{\circ}C$ as $Fe(OH)_3$ formed was insoluble, it was filtered of and to the filterate containing $NaAl(OH)_4(OH_2)_2$Carbon dioxide gas was bubbled at $50^{\circ}C~90^{\circ}C$ to obtain the precipitate with excellent filterability and crystallinity. The product was certified to be Dawsonite $(NaAl(OH)_2CO_3)$ by X-Ray diffraction analysis at below $40^{\circ}C$, when $CO_2$ gas was bubbled into the relatively lower concentration of $NaAl(OH)_4(OH_2)_2$ solution, the precipitate of very fine particles was formed, which was hard to filter and with the Composition of $\alpha-Al_2O_3-H_2O$ (Boehmite).

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.31-38
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• 2015

At present, carbon dioxide ($CO_2$) emission, which causes global warming, is a major issue all over the world. To reduce $CO_2$ emission directly, commercial deployment of $CO_2$ separation processes has been attempted in industrial plants, such as power plant, oil refinery and steelmaking plant. Besides, several studies have been done on indirect reduction of $CO_2$ emission from recycle of reducing gas (carbon monoxide or hydrogen containing gas) in the plants. Unlike many competing gas separation technologies, pressure swing adsorption (PSA) and membrane filtration are commercially used together or individually to separate a single component from the gas mixture. However, there are few studies on operation of sequential separation process of multi-component gas which has more than two target gas products. In this paper, process simulation model is first developed for two available configurations: $CO_2$ PSA-CO PSA-$H_2$ PSA and $CO_2$ PSA-CO PSA-$H_2$ membrane. Operation optimization and economic evaluation of the processes are also performed. As a result, feed gas contains about 14% of $H_2$ should be used as fuel than separating $H_2$, and $CO_2$ separation should be separated earlier than CO separation when feed gas contains about 30% of $CO_2$ and CO. The simulation results can help us to find an optimal process configuration and operation condition for separation of multicomponent gas with $CO_2$, CO, $H_2$ and other gases.

• Resources Recycling
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• v.24 no.2
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• pp.13-22
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• 2015

$CO_2$ emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30 % of $CO_2$ emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of $CO_2$ in the construction area as we reduce the second and third curing to emit $CO_2$ in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter "LA") to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.

• Animal Bioscience
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• v.37 no.2
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• pp.173-183
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• 2024

Objective: This study aimed to evaluate whether the methane (CH₄) to carbon dioxide (CO₂) ratio (CH₄/CO₂) and methane-related traits obtained by the sniffer method can be used as indicators for genetic selection of Holstein cows with lower CH₄ emissions. Methods: The sniffer method was used to simultaneously measure the concentrations of CH₄ and CO₂ during milking in each milking box of the automatic milking system to obtain CH₄/CO₂. Methane-related traits, which included CH₄ emissions, CH₄ per energy-corrected milk, methane conversion factor (MCF), and residual CH₄, were calculated. First, we investigated the impact of the model with and without body weight (BW) on the lactation stage and parity for predicting methane-related traits using a first on-farm dataset (Farm 1; 400 records for 74 Holstein cows). Second, we estimated the genetic parameters for CH₄/CO₂ and methane-related traits using a second on-farm dataset (Farm 2; 520 records for 182 Holstein cows). Third, we compared the repeatability and environmental effects on these traits in both farm datasets. Results: The data from Farm 1 revealed that MCF can be reliably evaluated during the lactation stage and parity, even when BW is excluded from the model. Farm 2 data revealed low heritability and moderate repeatability for CH₄/CO₂ (0.12 and 0.46, respectively) and MCF (0.13 and 0.38, respectively). In addition, the estimated genetic correlation of milk yield with CH₄/CO₂ was low (0.07) and that with MCF was moderate (-0.53). The on-farm data indicated that CH₄/CO₂ and MCF could be evaluated consistently during the lactation stage and parity with moderate repeatability on both farms. Conclusion: This study demonstrated the on-farm applicability of the sniffer method for selecting cows with low CH₄ emissions.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.448-454
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• 2007

Hydrothermal synthesis was conducted with starting material as Barium hydroxide and hydrous titania ($TiO_2{\cdot}xH_2O$) to obtain barium titanate fine Powder. The conversion, crystal structure and properties of as-prepared powder were investigated according to reaction temperature, time and concentration. The effect of variables on conversion was in order of time < temperature < concentration and the maximum conversion reached to 99.5% in the case of hydrothermal synthesis at $180^{\circ}C$ for 2 h with 2.0 M reactant concentration. At low concentration such as 0.25 M, formation of unreacted $BaCO_3$ and $TiO_2$ was not inevitable at even high reaction temperature and these components converted into $BaTi_2O_5$ at high temperature and remained as impurity. As concentration of reactant increased, the size of as-synthesized $BaTiO_3$ powder deceased and Ba/Ti molar ratio approached into 1, showing Ba/Ti ratio of $1{\pm}0.005$ for reaction at $180^{\circ}C$ for 2 h with 2.0 M concentration.