• Fire Science and Engineering
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• v.16 no.2
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• pp.51-58
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• 2002

For Halon-1301 regulated by Montreal Protocol and $CO_2$as its alternatives, the empirical equations of density, viscosity, and enthalpy were correlated in terms of temperature. They were obtained by regression analysis from the experimental data in the literature. The empirical equation of density was expressed as compressibility factor by the second- order function of temperature. The empirical equation of viscosity was formulated as a power function, and a correction factor was considered to cover the wider range of temperature. Finally, heat capacity as well as enthalpy were well fitted by empirical form of the second-order temperature. The correlation coefficients of the empirical equations in this work were more than 0.99.

• Advances in environmental research
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• v.9 no.2
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• pp.123-133
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• 2020

A time series dataset was conducted to ascertain the effect of water table on the variability in and emission of CH₄ and CO₂ concentrations at a closed landfill site. An in-situ data of methane/carbon dioxide concentrations and environmental parameters were collected by means of an in-borehole gas monitor, the Gasclam (Ion Science, UK). Linear regression analysis was used to determine the strength of the correlation between ground-gas concentration and water table. The result shows CH₄ and CO₂ concentrations to be variable with strong negative correlations of approximately 0.5 each with water table over the entire monitoring period. The R² was slightly improved by considering their concentration over single periods of increasing and decreasing water table, single periods of increasing water table, and single periods of decreasing water table; their correlations increased significantly at 95% confidence level. The result revealed that fluctuations in groundwater level is the key driving force on the emission of and variability in groundgas concentration and neither barometric pressure nor temperature. This finding further validates the earlier finding that atmospheric pressure - the acclaimed major control on the variability/migration of CH₄ and CO₂ concentrations on contaminated sites, is not always so.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.1-9
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• 2010

Since carbon dioxide, $CO_2$, was revealed as a major greenhouse gas, techniques for its separation, capture, and storage have received increasing interest in recent years. Aqueous amines are the most widely accepted $CO_2$ absorbents, but they cause the problems such as high regeneration energy, thermal degradation, and loss of absorbents due to their volatility. Ionic liquids having high thermal stability, extremely low vapor pressure, and capability of selectively absorbing specific gases have been proposed as new $CO_2$ capturing solvents which may potentially replace aqueous amines. By reviewing the ionic liquids having capability to absorb $CO_2$ reported in previous papers, we seek to develop a comprehensive understanding on the factors that influence the $CO_2$ solubility in ionic liquids such as their structures, absorption temperature, pressure, water content, etc., and to estimate the potential of ionic liquids as $CO_2$ separating media.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.403-410
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• 2020

This paper focuses on the design of a 12-kW small-scale supercritical CO₂ test loop. A theoretical study, stabilization, and optimization of carbon dioxide were carried out with the application of a solar heat source based on solar thermal data in Pohang. The thermodynamic cycle of the test facility is a Rankine cycle (transcritical cycle), which contains liquid, gas, and supercritical CO₂. The system is designed to achieve 6.98% efficiency at a maximum pressure of 12 MPa and a maximum temperature of 70℃. In addition, the optimum turbine inlet temperature and pressure were calculated to increase the cycle efficiency, and the application of an internal heat exchanger (IHX) was simulated. It was found that the maximum efficiency increases to 18.75%. The simulation confirmed that the efficiency of the cycle is 6.7% in May and 6.26% in June.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.306-311
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• 2000

Lipid and cholesterol were extracted from beef and pork by the supercritical carbon dioxide $(SC-CO_2)$ for the manufacturing of low-lipid and low-cholesterol sausage. The ranges of extraction temperature and pressure were from 35 to $55^{\circ}C$ and from 103 to 375 bar, respectively. $SC-CO_2$ extraction yield of beef lipid increased as extraction pressure increased and/or extraction temperature decreased, while extraction temperature was more influential on the cholesterol extraction than pressure condition. When lipid and cholesterol of freeze-dried beef with varied moisture contents were extracted, their solubilities increased as the moisture content reduced. The extraction of lipid and cholesterol from pork was shown the same tendency as the beef. The chunk type of beef shape was more suitable for the lipid and cholesterol extraction than the powder type of beef. The color of meat after $SC-CO_2$ extraction was lighter than the raw freeze dried meat because of the extraction of color pigments. After $SC-CO_2$ extraction, beef and pork were rehydrated and mixed with raw beef and pork containing lipid and cholesterol. Their mixing ratio up to 50 : 50 did not affect physical properties of the sausage compared with the control sausage.

• Membrane Journal
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• v.30 no.2
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• pp.97-110
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• 2020

CO₂ capture and storage (CCS) is one of the promising technologies that can mitigate ever-growing emission of anthropogenic carbon dioxide and resultant climate change. Among them, chemical looping combustion (CLC) and calcium looping (CaL) are getting increasing attention recently as the prospective alternatives to the existing amine scrubbing. Both methods use metal oxides in the process and consist of cyclic reactions. Yet, due to their cyclic nature, they both need to resolve sintering-induced cyclic stability deterioration. Moreover, the structure of the metal oxides needs to be optimized to enhance the overall performance of CO₂ capture and storage. Deposition of thin film coating on the metal oxide is another way to get rid of wear and tear during the sintering process. Chemical vapor deposition or atomic layer deposition are the well-known, established methods to form thin film membranes, which will be discussed in this review. Various effective recent developments on structural modification of metal oxide and incorporation of stabilizers for cyclic stability are also discussed.

• Clean Technology
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• v.21 no.1
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• pp.53-61
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• 2015

In this study, we have investigated the kinetics on the char-CO₂ catalytic gasification reaction. Thermogravimetric analysis (TGA) experiments were carried out for char-CO₂ catalytic gasification of an Indonesian Kideco sub-bituminous. Na₂CO₃ and K₂CO₃ were selected as catalysts which were physically mixed with coal. The char-CO₂ catalytic gasification reaction showed a rapid increase of carbon conversion rate at 850 ℃, 60 vol% CO₂, and 7 wt% Na₂CO₃. At the isothermal conditions ranging from 750 ℃ to 900 ℃, the carbon conversion rates increased as the temperature increased. Four kinetic models for gas-solid reaction including the shrinking core model (SCM), random pore model (RPM), volumetric reaction model (VRM), and modified volumetric reaction model (MVRM) were applied to the experimental data against the measured kinetic data. The gasification kinetics were suitably described by the MVRM for the Kideco sub-bituminous. The activation energies for each char mixed with Na₂CO₃ and K₂CO₃ were found 55-71 kJ/mol and 69-87 kJ/mol.

• Fire Science and Engineering
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• v.25 no.3
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• pp.119-124
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• 2011

In this study, we measured the smoke density characteristics to find the fire risk of Wood-Plastic composites (WPCs) which are one of spotlighting materials for landscape architecture and residential construction material with the cone calorimeter tester (by ISO 5660-2) and the smoke density tester (by ASTM E 662). In addition, the identical test was implemented to compare the smoke density characteristics between the red pine and the antiseptic wood. The result of cone calorimeter test showed that emissions of carbon monoxide, carbon dioxide and total smoke production rate of WPCs were higher than those of red pine and antiseptic wood. And the result of smoke density test showed that maximum specific optical smoke density(Dm) of WPCs was higher than that of red pine and antiseptic wood as well.

• Journal of Hydrogen and New Energy
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• v.15 no.3
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• pp.208-219
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• 2004

To find a suitable oxygen carrier particle for a 50kW chemical-looping combustor, which was designed and installed to demonstrate continuous oxidation and reduction, three oxygen carrier particles(NiO/bentonite, $NiO/NiAl_2O_4$, $CoO_x/CoAl_2O_4$) were prepared. The reactivity and the attrition resistance of particles were measured and investigated by a thermo-gravimetrical analyzer and an attrition test apparatus respectively. From the viewpoints of oxygen transfer capacity, optimum reaction temperature(operating temperature range), reaction rate, carbon deposition rate, and attrition resistance, NiO/bentonite particle showed better performance than the other particles, therefore we selected NiO/bentonite particle as an optimum oxygen carrier particle.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.2
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• pp.198-204
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• 1998

This study was conducted to evaluate the effect of far IR radiation for the elimination of sidestream smoke components in a closed room. The measurements covered particle sizes of 13.8-542.5 nm, particle concentration, TSP, UVPM, FPM, solanesol, and the following gases and vapor components of smoke: carbon dioxide, carbon monoxide, nicotine, and 3-ethenyl-pyridine. Also, the changes of smoke odor strength by far IR radiation were tested by using the electronic nose system. There was no difference between control and far IR radiation in changes of the concentration of $CO_2$ and CO. The concentrations of TSP, UVPM, FPM, solanesol, nicotine, and 3-ethenylpyridine were reduced by far IR radiation. The growth and diminishing rate of RSP diameter was accelerated by far IR radiation compared with control. There was a little difference of smoke odor change with far IR radiation by electronic nose system analysis. Our results indicated that the use of far IR radiation had a little effect on changes of solid, vapor, and odor of smoke, but it had no effect on gaseous components.