• Applied Biological Chemistry
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• v.41 no.5
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• pp.363-366
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• 1998

Supercritical fluid(SCF) carbon dioxide was used to extract safflower yellow pigments from Carthamus tinctorius L. In this work, supercritical fluid extractions were performed at various conditions; pressure (2000, 3000, 4000, 5000 psig), temperature $(40,\;50,\;60,\;70,\;80^{\circ}C)$ and co-solvent $(0,\;3,\;6,\;10,\;14\;wt%\;H_2O)$. Total concentrations of safflower yellow pigments extracted were determined by spectrophotometric method. A maximum yield of yellow pigments was obtained at 4000psig, $60^{\circ}C$ and 10% co-solvent. The extraction yield of pigments was also closely related to moisture content of the raw material. Extraction yield of safflower yellow pigments by SCF extraction at optimized conditions was 6% higher than that by solvent extraction. Supercritical carbon dioxide was proved to be suitable for the extraction of safflower yellow pigments from Carthamus tinctorius L.

• Clean Technology
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• v.13 no.2
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• pp.99-103
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• 2007

Pt/Nafion self-humidifying membranes for Polymer Electrolyte Membrane Fuel Cell (PEMFC) were synthesized via a supercritical-impregnation method. The Nafion 112 membranes were impregnated with Pt(II) acetylacetonate from a supercritical carbon dioxide ($scCO_2$) solution at $80^{\circ}C$ and 19.8 MPa. After the impregnation, the Pt-impregnated Nafion membrane was converted Pt deposited Nafion(Pt/Nafion) membrane by reducing agent, sodium borohydride ($NaBH_4$) under $50^{\circ}C$ and 2 hours. The prepared Pt/Nafion membranes were investigated by SEM, EDS and EPMA. The performance of the Pt/Nafion membranes was examined in PEMFC as a self-humidifying membrane. The cell performance of the Pt/Nafion membrane at $65^{\circ}C$ is better than that of Nafion 112.

• Journal of the Korean Institute of Educational Facilities
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• v.25 no.2
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• pp.3-9
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• 2018

This study is designed to measure the indoor environment and research on the environmental situation in the lecture room where the lecture is conducted during the winter time in order to understand the level of environment in the lecture room and then suggest the method of improving the environment in the lecture room in the future. The findings are as follows. First, the number of ventilation measured at Lecture Room 1 was 1.2 times/hour while that at Lecture Room 2 was 2.2 times/hour. Second, the lighting at Lecture Room 1 and 2 was 650~700 lux while the noise at Lecture Room 1 and 2 was not more than 60dB. Third, Group 1 and Group 2 felt in the same way that the air quality in the lecture room was not good when the air quality was measured in 30 minutes after the start of lecture. Fourth, both Group 1 and Group 2 showed the lowered concentration on the class in 30 minutes after the start of the class when the room was heated. But Group 1 got less drop in the concentration when they was put in the non-heated room. Fifth, As for the change in the carbon dioxide volume during lecture, the carbon dioxide volume in the room where the windows was closed rose 1,000~1,400ppm from that at the time of start, thus showing that the indoor air quality got worsened. In addition, it is hard to control the indoor temperature due to the heating and non-heating. Accordingly, it is necessary to get the heating system which can make the ventilation in order to keep the environmental level in the lecture room to a certain level and keep the proper indoor temperature.

• Membrane Journal
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• v.13 no.3
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• pp.200-209
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• 2003

Polymer-metal complexed membranes were prepared by solvent evaporation method using ethylcellulose, platinum(II)acetylacetonate, and rhodium(III)acetylacetonate. The various composition of metal salt(0.3-4.0 wt%) were employed to obtain the optimum performance of final membrane. EC-metal complexed membranes were characterized by FTIR and scanning electron microscopy(SEM) to observe the morphology and the performance of oxygen, nitrogen, carbon dioxide, and methane gases was tested. It was shown that the metal salts enhanced the permeability of all gases without decrease of selectivity. However, it was found that Pt had more effects on the permeability of oxygen and nitrogen gases while Rh had more effects on the permeability of carbon dioxide and methane gases. EC-Pt complexed membrane(Pt 1.0 wt%) even showed the enhanced selectivity of oxygen/nitrogen(37%) due to the affinity characteristic of Pt to oxygen.

• Food Science and Preservation
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• v.16 no.4
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• pp.482-489
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• 2009

We investigated how supercritical $CO_2$ affected sterilization and enzyme inactivation in dongchimi, a conventional Korean fermented food. The growth of bacteria, including lactic acid bacteria, in dongchimi juice tended to decrease with increased pressure and temperature during treatment with supercritical $CO_2$. D values were affected by pressure more than by temperature. The lowest total number of cells and D values of lactic acid bacteria were observed after treatment with supercritical $CO_2$ at 25 MPa and $25^{\circ}C$; these conditions also reduced polygalacturonase activity in radishes by approximately 40.3%. Supercritical $CO_2$ can be used as an alternative method of sterilization and enzyme inactivation, minimizing sensory loss and textural changes in vegetable materials.

• Membrane Journal
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• v.31 no.6
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• pp.456-470
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• 2021

In this study, polyetherimide-based hollow fiber membranes were manufactured using the NIPS (nonsolvent induced phase separation) method. THF, Ethanol, and LiNO₃ were used as additives to control the morphology of the PEI-hollow fiber membranes. Furthermore, for the development of a high hydrogen separation membrane, the spinning conditions were optimized through the characterization of SEM and gas permeance. As a result, as the content of THF increased, the hydrogen/carbon dioxide selectivity increased. However, the permeance decreased due to the trade-off relationship. When ethanol was added, a finger-like structure was shown, and when LiNO₃ was added, a sponge structure was shown. In particular, in the case of a hollow fiber membrane with an optimized PDMS coating layer, the permeance was 40 GPU and the hydrogen/carbon dioxide selectivity was 5.6.

• Journal of Environmental Science International
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• v.14 no.6
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• pp.555-563
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• 2005

This study presents the characteristics of nocturnal inversion layer and their effect on the concentration variations of surface air pollutants using tethersonde and automatic weather station (AWS, 2 layer tower) system in Ulsan during 2003, The method for the distinction of inversion intensity was decided based on the sum of nocturnal temperature gradient. As the results, there was a close correlation (correlation coefficient of 0,76) between the maximum inversion height obtained from tethersonde and the sum of nocturnal temperature gradient. The air pollutant concentration was also directly proportional to the inversion intensity. When the inversion intensity was strong in the nighttime, ozone $(O_3)$ concentration was lower, while nitrogen dioxide $(NO_2)$ concentration was higher. The carbon monoxide (CO) concentration was gradually higher according to the nocturnal inversion intensity, whereas sulfur dioxide $(SO_2)$ concentration was relatively constant. In addition, we found that there was no correlation between the inversion intensity and TSP concentration.

• Journal of Animal Science and Technology
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• v.66 no.2
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• pp.237-250
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• 2024

The emission of noxious gases is a significant problem in pig production, as it can lead to poor production, welfare concerns, and environmental pollution. The noxious gases are the gasses emitted from the pig manure that contribute to air pollution. The increased concentration of various harmful gasses can pose health risks to both animals and humans. The major gases produced in the pig farm include methane, hydrogen sulfide, carbon dioxide, ammonia, sulfur dioxide and volatile fatty acids, which are mainly derived from the fermentation of undigested or poorly digested nutrients. Nowadays research has focused on more holistic approaches to obtain a healthy farm environment that helps animal production. The use of probiotics, prebiotics, dietary enzymes, and medicinal plants in animal diets has been explored as a means of reducing harmful gas emissions. This review paper focuses on the harmful gas emissions from pig farm, the mechanisms of gas production, and strategies for reducing these emissions. Additionally, various methods for reducing gas in pigs, including probiotic interventions; prebiotic interventions, dietary enzymes supplementation, and use of medicinal plants and organic acids are discussed. Overall, this paper provides a comprehensive review of the current state of knowledge on reducing noxious gas in pigs and offers valuable insights for pig producers, nutritionists, and researchers working in this area.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.49-54
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• 2004

Detailed flame structures of the opposed flames formed for different oxidant compositions are studied numerically. The detailed chemical reactions are modeled by using the CHEMKIN code. Only the $CO_2$ and $H_2O$ are assumed to participate by absorbing the radiative energy while all other gases are assumed to be transparent. The discrete ordinates method and the narrow band based WSGGM with a gray gas regrouping technique are applied for modeling the radiative transfer through non-homogeneous and non-isothermal combustion gas mixtures generated by the opposed flow flames. The results show that the different radiation model can cause different results for flame structures and the WSGGM with gray gas regrouping is successful in modeling the opposed flames with non-gray gas mixture. The numerical results show that the increases in $CO_2$ and $H_2O$ compositions cause to reduce the flame temperature and the NO formation.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.196-201
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• 2009

Global warming issues due to the $CO_2$(Carbon Dioxide) become increasing since the Industrial Revolution. After the Kyoto protocol at 1997, nations which have the prearranged quota drives their national project for the reduction of $CO_2$. Korean Government start to the related big projects in the view of three concepts which have consist of the $CO_2$ exhaust reduction on land, $CO_2$ capture and $CO_2$ storage. Furthermore, the storage method putting into depleted region underground is accepted by the London Convention while the ocean diluted method discharging the liquid $CO_2$ into the deep ocean using the long pipe which is towed by the surface vessel is underway for the research steps which means that there are many potentials for the R&Ds that need for the breakthrough. In this paper, the role and example of the Computational Fluid Dynamics for the feasibility study of the $CO_2$ ocean sequestration is mentioned.