• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.207-212
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• 2001

Supercritical fluid extraction was explored as a method for removing lipids and bad odor from tuna viscera. Selected conditions of extraction pressure, time, temperature and sample size were evaluated for effective removal of lipids and bad odor, Supercritical carbon dioxide was used as a solvent and the extraction was performed at semi-batch flow type. The experimental conditions used in this work was the range of pressure from 1,500 psig to 2,000 psig, the temperature from $25^{\circ}C\;to\;40^{\circ}C$ and dried sample size from 0.2 mm to 1.0 mm. The main fatty acids extracted from tuna viscera were palmitic acid (16: 0) heptadecenoic acid (17: 1) oleic acid (18: 1) and docosahexaenoic acid (22: 6). Protein concentrate was obtained without deformation the optimum condition at $35^{\circ}C$, 1,800 psig and 0.25 mm of the size. In the concentrate after supercritical carbon dioxide extraction, the major amino acids were glutamic acid, leucine and lysine.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.790-795
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• 1996

Citrus juice was treated with supercritical carbon dioxide $(SC-CO_{2})$ as an alternative to heat for pectinesterase (PE) inactivation to minimize undesirable changes in flavor, color and ascorbic acid loss caused by the current heat treatment, and the effect of temperature $(40,\;50,\;60^{\circ}C)$, pressure (138, 276 bar) and process time $(5{\sim}130\;min) $ on PE activity was determined. PE in temperature control samples was inactivated by 54% at $40^{\circ}C$ after 130 min, 84% at 50% after 60 min and 83% at $60^{\circ}C$ after 30 min treatment compared to the original juice. PE inactivation in $(SC-CO_{2})$ treated samples at 138 bar was 83% at $40^{\circ}C$ after 130 min, 88% at $50^{\circ}C$ after 20 min and 87% at $60^{\circ}C$ after 10 min. %PE inactivation due to pressure was higher at low temperature and lower at high temperature. Higher temperature, Pressure and longer process time resulted in higher %PE inactivation. Nonlinearity in the curves of PE inactivation at different temperatures and pressures indicated that at least two forms of PE existed in citrus juice with different stabilities.

• KSBB Journal
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• v.19 no.6 s.89
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• pp.427-432
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• 2004

The purpose of this study is to investigate the feasibility of a cosolvent-modified supercritical $CO_2\;(scCO_2)$ extraction technique for the production of licorice extracts with high levels of glabridin. The effects of various parameters such as the type and amount of modifiers, extraction temperature ($40{\sim}80^{\circ}C$) and pressure ($10{\sim}50.0\;MPa$) on the extraction efficiency were examined at a fixed flow rate of 1 mL/min. The organic solvent extraction with pure methanol was also conducted for a quantitative comparison with the $scCO_2$ extraction. The recovery of glabridin from licorice was found to be extremely small for pure $scCO_2$. However, the addition of modifiers such as ethanol and acetone to $scCO_2$ resulted in a significant improvement in the recovery of glabridin. The recovery of glabridin was observed to increase with pressure at a constant temperature. Furthermore, the purity of the glabridin obtained from the $scCO_2$ extraction was higher compared with the organic solvent extraction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.333-338
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• 2022

The single jet of decane/methylcyclohexane mixed fuel that is surrogate for kerosene was injected into supercritical environment and visualized using shadowgraph technique. The injection pressure drop of the fuel jet of T_r = 0.484 was kept constant at 0.5 MPa and the experiment was conducted above the critical point of the mixed fuel, and the reduced temperatures of the chamber was changed from 1.00 to 1.23, and the reduced pressures was 1.00 and 1.38. As an index for reducing the density of jets sprayed into the supercritical environment, the brightness intensity of the post-processed jet image was observed with the internal temperature and pressure of the chamber. It was confirmed that the decrease in the brightness intensity of the jet when the temperature inside the chamber increased, and when the pressure inside the chamber was higher at the same temperature, the decrease in the brightness intensity of the jet was delayed. When the pressure inside the chamber is high, it is thought that the change in brightness intensity is delayed due to the increase in the pseudo-critical temperature of the fuel and the increase in the temperature required to reduce the density of the fuel jet.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.32-38
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• 2009

In this paper, cycle performance analysis for cooling capacity, compression work and COP of R744($CO_2$) transcritical vapor compression refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include superheating degree, outlet temperature of gas cooler and evaporating temperature in the R744 vapor compression cycle. The main results were summarized as follows : The cooling capacity of R744 increases with superheating degree, but decreases with the increasing evaporating temperature and outlet temperature of gas cooler. The compression work increases with superheating degree and cooling pressure of R744, but decreases with the increasing evaporating temperature. And, The COP increases with outlet temperature and evaporating temperature of R744 gas cooler, but decreases with the increasing superheating degree. Therefore, superheating degree, outlet temperature and evaporating temperature of R744 vapor compression refrigeration system have an effect on the cooling capacity, compression work and COP of this system. With a thorough grasp of these effect, it is necessary to design the compression refrigeration cycle using R744.

• 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.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.750-755
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• 1996

Citrus juice was treated with supercritical carbon dioxide $(SC-CO_{2})$ and the effect of temperature and pressure on quality of citrus juice was determined. Pectinesterase (PE) was inactivated by $(SC-CO_{2})$ below temperatures necessary for thermal inactivation. There was no significant change in the pH, Brix and total acidity of citrus juice before and after $(SC-CO_{2})$ treatment, but brightness was improved. More ascorbic acid was retained during $(SC-CO_{2})$ treatment of citrus juice than thermal treatment $(93^{\circ}C/0.66\;min)$.During storage of supercritically treated citrus juice at $4^{\circ}C$, activity of PE was reversible. Sensory evaluation showed that color, flavor, taste and overall acceptance of $(SC-CO_{2})$ treated juice were not significantly different from untreated juice. This method offers potentially beneficial processing avenues for citrus juice and other juices, especially in the area of minimally processed products.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.678-683
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• 2012

Ceria is one of the most important catalytic materials which can be used in three-way catalysts, waste water treatment, petroleum refining, etc. So far, many methods have been studied to produce ceria nanoparticles. In this study, ceria nanoparticles were prepared via solvothermal synthesis using supercritical methanol in short reaction time using a batch reactor. The size of synthesized ceria nanoparticles in supercritical methanol is 6 nm without capping agent, which is smaller than that made in supercritical water at the same conditions of $400^{\circ}C$ and 30 MPa. Size difference results from density and critical point difference between water and methanol and slow reaction rate at the surface of ceria particles in supercritical methanol which reduces crystal growth rate. Several organic compounds were added to modify the surface of ceria nanoparticles, and in-situ surface modification was confirmed by FT-IR and TGA analysis. Surface modified ceria nanoparticles have excellent dispersibility in organic solvent. Size and shape of surface modified ceria particles can be controlled by adjusting molar ratio of modifier to precursor and selection of modifier.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.71-78
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• 2005

The vaporization characteristics of a liquid heptane droplet in a supercritical nitrogen flow is numerically analyzed. The present model can account for real gas effects, liquid-phase internal circulation, variable thermodynamic properties and high-pressure effects. Time marching method with preconditioning scheme is employed to handle the low Mach number flows in dense heptane droplet region. Computations are made for the wide range of convective velocity and ambient pressure. Numerical results indicate that the droplet deformation becomes stronger by increasing the Reynolds number and it becomes relatively weak by increasing the pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.85-88
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• 2010

This study has been mainly motivated to numerically model the supercritical mixing and combustion processes encountered in the liquid propellant rocket engines. In the present approach, turbulence is represented by the extended $k-{\varepsilon}$ turbulence model. To account for the real fluid effects, the propellant mixture properties are calculated by using SRK (Souve-Redlich-Kwong) equation of state. In order to realistically represent the turbulence-chemistry interaction in the turbulent nonpremixed flames, the flamelet approach based on the real fluid flamelet library has been adopted. Based on numerical results, the detailed discussions are made for the real fluid effects and the precise structure of gaseous methane/liquid oxygen coaxial jet flame.