• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.169-172
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• 2005

We present CO(3-2), CO(2-1), and 230 GHz (1.3 mm) continuum images of nearby galaxies taken with the Submillimeter Array (SMA). Our main topic is to study the relation between higher-J molecular gas (e.g., CO J=3-2, 2-1) and nuclear activities (e.g., active galactic nuclei [AGNs] and starbursts). The nearby Seyfert 2 galaxy M51 shows strong CO(3-2) emission from the circumnuclear molecular gas, with an intensity twice as strong as that of the CO(1-0) emission. Strong CO(3-2) emission enhancement suggests that the circum nuclear molecular gas in M51 is warm and dense, which may be related to the AGN activities. Molecular gas in the nearby moderate starburst galaxy NGC 6946 is distributed along the large-scale bar or spiral arms and along the minibar, and the multi-J CO line images show very similar distribution to each other. For this galaxy, there is no clear enhancement in higher-J lines as seen in M51, which may be because NGC 6946 does not have clear AGN activities. Based on the results of these two galaxies, the physical conditions of the circum nuclear molecular gas may be related to the AGN activities. We also observed the nearby edge-on starburst galaxy NGC 3628 and the starburst/Seyfert composite galaxy NGC 4945 with the CO(2-1) line and 230 GHz (1.3 mm) continuum emission. These information will give us some hints for understanding the relation between nuclear activities and circum nuclear molecular gas and dust.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.171-176
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• 2016

Sour gas is natural gas or any other gas containing significant amounts of hydrogen sulfide ($H_2S$). Natural gas is usually considered sour gas if there are more than 5.7 milligrams of $H_2S$ per cubic meter of natural gas, which is equivalent to approximately 4 ppm by volume under standard temperature and pressure We have surveyed on the treatment and removal technology of sour gas, sour gas include a lot of hydrogen sulfide($H_2S$), Carbon dioxide($CO_2$), utane($C_4H_{10}$) and mercaptan($C_nH_{4n-1}SH$) etc. We need high technology for development for these kinds of raw gases and we should specially take care of treating and removal of theses raw gases. Therefor we are going to describe about these kinds of raw gases and about methods how to treat these kinds of gases.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.95-98
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• 1999

Chinese cabbage (Brassica campestris), one of the major vegetable crops in Korea, undergoes self-incompatible pathway for reproduction. To maintain inbred lines of chinese cabbage, a method in that $CO_2$ gas is treated to the pistils to break the self-incompatibility and thereby self-pollens can successfully make germination and fertilization has been selectively used in speed company. In this study, the pistil genes induced by the $CO_2$ treatment was investigated by mRNA differential display (DD-PCR) method. The result shows PCR products amplified in a differential pattern from both $CO_2$ gas treated- and untreated-pistil mRNAs, suggesting that the pistil genes are probably regulated positively and also negatively by the $CO_2$ gas.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.8-12
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• 2019

Thermal amine scrubbing is the most advanced CO₂ capture technique but its largescale application is hindered due to the large heat requirement during solvent regeneration step. The addition of a solid metal oxide catalysts can optimize the CO₂ desorption rate and thus minimize the energy consumption. Herein, we evaluate the solvent regeneration performance of Monoethanolamine (MEA) and Diethanolamine (DEA) solvents without and with two metal oxide catalysts (TiO₂ and V₂O₅) within a temperature range of 40-86℃. The solvent regeneration performance was evaluated in terms of CO₂ desorption rate and overall amount of CO₂ desorbed during the experiments. Both catalysts improved the solvent regeneration performance by desorbing greater amounts of CO₂ with higher CO₂ desorption rates at low temperature. Improvements of 86% and 50% in the CO₂ desorption rate were made by the catalysts for MEA and DEA solvents, respectively. The total amount of the desorbed CO₂ also improved by 17% and 13% from MEA and DEA solvents, respectively. The metal oxide catalyst-aided regeneration of amine solutions can be a new approach to minimize the heat requirement during solvent regeneration and thus can remove a primary shortfall of this technology.

• Membrane Journal
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• v.21 no.3
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• pp.290-298
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• 2011

The influence of co-existing gases on the hydrogen permeation was studied through a Pd-coated $V_{53}Ti_{26}Ni_{21}$ alloy membrane. The hydrogen permeation characteristics of Pd-coated $V_{53}Ti_{26}Ni_{21}$ alloy membrane have been investigated in the pressure range 1-3 bar under pure hydrogen and hydrogen mixture gas with carbon dioxide and carbon monoxide at $450^{\circ}C$. Preliminary hydrogen permeation experiments have been confirmed that hydrogen flux was $5.36mL/min/cm^2$ for a Pd-coated $V_{53}Ti_{26}Ni_{21}$ alloy membrane (thick: 0.5 mm) using pure hydrogen as the feed gas. In addition, hydrogen fluxes were 4.46, 5.20, $3.91mL /min/cm^2$ for$V_{53}Ti_{26}Ni_{21}$ alloy membrane using $H_2/CO_2$, $H_2/CO$ and $H_2/CO_2/CO$ as the feed gas respectively. Therefore, the hydrogen permeation flux decreased with decrease of hydrogen partial pressure irrespective of temperature and pressure when $H_2/CO_2$, $H_2/CO$ and $H_2/CO_2/CO$ mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert's law in different feed conditions. It was found from XRD results after permeation test that the Pd-coated $V_{53}Ti_{26}Ni_{21}$ alloy membrane had good stability and durability for various mixtures feeding condition.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.77.2-77.2
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• 2015

Galaxies are known to evolve passively in the cluster environment. Indeed, much evidence for HI stripping has been found in cluster galaxies to date, which is likely to be connected to their low star formation rate. What is still puzzling however, is that the molecular gas, which is believed to be more directly related to star formation, shows no significant difference in its fraction between the cluster population and the field galaxies. Therefore, HI stripping alone does not seem to be enough to fully understand how galaxies become passive in galaxy clusters. Intriguingly, our recent high resolution CO study of a subsample of Virgo spirals which are undergoing strong ICM pressure has revealed a highly disturbed molecular gas morphology and kinematics. The morphological and kinematical peculiarities in their CO data have many properties in common with those of HI gas in the sample, indicating that strong ICM pressure in fact can have impacts on dense gas deep inside of a galaxy. This implies that it is the molecular gas conditions rather than the molecular gas stripping which is more responsible for quenching of star formation in cluster galaxies. In this study, using multi transitions of 12CO and 13CO, we investigate the density and temperature distributions of CO gas of a Virgo spiral galaxy, NGC 4402 to probe the physical and chemical properties of molecular gas and their relations to star formation activities.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.91-95
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• 2012

ZnO thin films were deposited on p-type 4H-SiC substrate by pulsed laser deposition. ZnO nanowires were formed on p-type 4H-SiC substrate by furnace. Ti/Au electrodes were deposited on ZnO thin film/SiC and ZnO nanowire/SiC structures, respectively. Structural and crystallographical properties of the fabricated ZnO thin film/SiC and ZnO nanowire/SiC structures were investigated by field emission scanning electron microscope and X-ray diffraction. In this work, resistance and sensitivity of ZnO thin film/SiC gas sensor and ZnO nanowire/SiC gas sensor were measured at $300^{\circ}C$ with various CO gas concentrations (0%, 90%, 70%, and 50%). Resistance of gas sensor decreases at CO gas atmosphere. Sensitivity of ZnO nanowire/SiC gas sensor is twice as big as sensitivity of ZnO thin film/SiC gas sensor.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.5
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• pp.61-72
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• 2015

This study was reviewed the national greenhouse gas inventory report (NIR) of Annex I countries and estimated national greenhouse gas inventory on wetlands in Korea. Annex I countries submitted National Inventory Report which are focused on land converted to wetlands category and wetland remaining wetland (mainly peat lands) because IPCC did not suggest a formal methodology on flooded land. So we conducted a study on estimating of national greenhouse gas inventory in wetland (flooded land). The total annual $CO_2-eq.$ emission of wetland remaining wetland (flooded land) was ranged from 99.9 Gg $CO_2-eq.$ to 237.1 Gg $CO_2-eq.$ from 1990 to 2012. The $CO_2-eq.$ emissions was declined after peaking in 1995, however, it slightly increasing in recently years. The latest total $CO_2-eq.$ emission from flooded land was 117.7 Gg $CO_2-eq.$ in 2012 which was covered only 0.00002% of national GHG inventory. This means that flooded land is not key-category in Korea. We will consider an improvement for emissions of flooded land, if IPCC suggest formal or complementary methodology.

• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.51-54
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• 2007

78-cell proton exchange membrane fuel cell(PEMFC) stack with an effective electrode area of $295cm^{2}$ were investigated its operational characteristics and effects of CO poisoning. When power output, 5.4 kW, was released at current density of $325mA/cm^{2}$ for 6 hours, stablility of each cell was showed the small deviation of 2.3%. Carbon monoxide is a conventional contaminant in the fuel obtained from reforming processes with an important influence on the performance of the PEMFC. The studies of continuous injection of CO presented (5-20 ppm) with the time gave information about poisoning and recovery processes of the stack.

• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.294-299
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• 2018

This article describes the output properties of non-dispersive infrared carbon dioxide($CO_2$) sensors resulting from the changes in ambient temperatures. After the developed sensor module was installed inside the gas chamber, the temperature was set to 267 K, 277 K, 300 K, and 314 K, and the concentrations of $CO_2$ gas were increased from 0 to 5,000 ppm. Then, the output voltage at each concentration was obtained. Through these experimental results, two observations were made. First, both the $CO_2$ sensor and the reference sensor showed an increase in the output voltages as the temperature rose from 0 ppm, Second, the full scale outputs of the $CO_2$ sensor grew as the temperature increased. The output characteristics were analyzed based on two factors: change in the radiant energy of the infrared light source and change in the absorptivity of $CO_2$ gas according to the ambient temperature. Additionally, temperature compensation methods were discussed.