• Nuclear Engineering and Technology
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• v.40 no.2
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• pp.107-116
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• 2008

The present paper describes the preliminary compilation, assessment and examination of the supercritical heat transfer(SCHT) database. The availability and reliability of the SCHT data are discussed. Similarities in thermodynamic supercritical properties and SCHT behaviour of water, $CO_{2}$ and R-134a have been examined and some tentative conclusions are made. Finally, the future experimental and analytical program at the University of Ottawa is described.

• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.625-631
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• 2000

In this study, the characteristics and sinterablities of TiO2 powders which were fabricated on sol-gel process and supercritical fluid process were examined. The powders fabricated on sol-gel process were amorphous. The particle size and shape were changed with the amount of water used for hydrolysis of titanium ethoxide. The powders were changed from amorphous to crystalline by heating at 400℃. The crystalline anatase TiO2 powders were directly prepared in ethanol supercritical fluid condition that temperature was 270±3℃ and pressure was 7.3 MPa. It's primary crystalline size was 20 nm and agglomerated as spherical shape whose size was 0.7∼1㎛. The powders prepared on sol-gel process were not sintered densely at 900℃ because of abnormal grain growth. However, the powders which prepared on supercritical fluid process were sintered densely at the comparatively low temperature of 800℃ by ideal growth of grain, which are fired at 900℃.

• KSBB Journal
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• v.23 no.2
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• pp.147-152
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• 2008

The variety of functional plants has an attention for new natural food preservation and natural antiseptic development. The extracts from functional plants with various methods (ethanol extraction, hot water extraction and supercritical fluid extraction) tested antimicrobial activity against 10 strains including the pathogenic and food poisoning bacteria, the yeast and fungi. The antimicrobial activities of supercritical fluid extracts were shown higher than ethanol extract and hot water extract when tested with disc-diffusion method and minimum inhibitory concentration (MIC). Antimicrobial activity of supercritical fluid extract was two times higher than ethanol extract in Cinnaonomum cassia. In addition, the supercritical fluid extractions of Chamaecyparis obtuas and the C. cassia showed the higher yield than Origanum vulgare and Scutellariae baicalensis. The supercritical fluid extract of C. cassia showed an antimicrobial activity against all strains tested. The supercritical fluid extract of S. baicalensis showed strong antimicrobial activity on Listeria monocytogenes. Supercritical fluid extraction of O. vulgare and C. obtuas showed strong antimicrobial activity on Salmonella typhimuriium. In MIC test, C. obtuas was shown the best natural material for the preparation of natural antimicrobial agent by supercritical fluid extraction. In conclusion, these results suggest that supercritical fluid extraction technique was effective to obtain functional ingredient with higher antimicrobial activity in the development of new antimicrobial reagent from natural materials.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.321-330
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• 1995

Homogeneous and monolithic TiO2-SiO2 binary aerogels were prepared by supercritical drying. Optical transparency was increased with adding acid catalyst during two step hydrolysis and with decreasing water content. These differences in optical transparency were related to microstructures of gel network formed through polycondensation reaction during supercritical drying process, rather than the final composition of aerogel.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.317-320
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• 2004

Physiological effects of curcumin, major yellow-colored pigment in tumeric (Curcuma longa L.), extracted by traditional extracting methods, ethanol and hot-water extractions, and supercritical fluid extraction (SFE) using supercritical carbon dioxide as new extracting method. Antioxidative activity of ethanol extract was higher than those of SFE and hot-water extracts. Results of Ames mutagenicity test on SFE, ethanol, and hot-water extracts revealed no mutagen in the extracts. Antimutagenicity rates of SFE, ethanol, and hot-water extracts against direct mutagen, 2-nitrofluorene (2-NF), were 20.1, 9.3, and 15.2%, respectively. Antimutagenicity rate of SFE extract against TA98 derived from indirect mutagen, 2-acetamidofluorene (2-AF), was 12.2%, whereas none was observed in ethanol and hot-water extracts. Nitrite-scavenging ability of SFE extract was higher than those of ethanol and not-water extracts.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.25-32
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• 2004

We have carried out laboratory measurements of P-wave velocity and deformation strain during $CO_2$ injection into a porous sandstone sample, in dry and water-saturated conditions. The rock sample was cylindrical, with the axis normal to the bedding plane, and fluid injection was performed from one end. Using a piezoelectric transducer array system, we mapped fluid movement during injection of distilled water into dry sandstone, and of gaseous, liquid, and supercritical $CO_2$ into a water-saturated sample. The velocity changes caused by water injection ranged from $5.61\;to\;7.52\%$. The velocity changes caused by $CO_2$ injection are typically about $-6\%$, and about $-10\%$ for injection of supercritical $CO_2$, Such changes in velocity show that the seismic method may be useful in mapping $CO_2$ movement in the subsurface. Strain normal to the bedding plane was greater than strain parallel to the bedding plane during $CO_2$ injection; injection of supercritical $CO_2$ showed a particularly strong effect. Strain changes suggest the possibility of monitoring rock mass deformation by using borehole tiltmeters at geological sequestration sites. We also found differences associated with $CO_2$ phases in velocity and strain changes during injection.

• Nuclear Engineering and Technology
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• v.40 no.2
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• pp.117-126
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• 2008

In this paper, a new reactor core design is proposed on the basis of a mixed core concept consisting of a thermal zone and a fast zone. The geometric structure of the fuel assembly of the thermal zone is similar to that of a conventional thermal supercritical water-cooled reactor(SCWR) core with two fuel pin rows between the moderator channels. In spite of the counter-current flow mode, the co-current flow mode is used to simplify the design of the reactor core and the fuel assembly. The water temperature at the exit of the thermal zone is much lower than the water temperature at the outlet of the pressure vessel. This lower temperature reduces the maximum cladding temperature of the thermal zone. Furthermore, due to the high velocity of the fast zone, a wider lattice can be used in the fuel assembly and the nonuniformity of the local heat transfer can be minimized. This mixed core, which combines the merits of some existing thermal SCWR cores and fast SCWR cores, is proposed for further detailed analysis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.1
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• pp.20-24
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• 2010

This study was performed to investigate antioxidant activities of Mistletoe (MS) extracts by measuring electron donating ability (EDA), super oxide dismutase (SOD)-like activity and total polyphenol content (TPC). The extracts were obtained using supercritical carbon dioxide, hot-water and ethanol extraction. EDAs was the higher in ethanol extract (70.53%) than water (36.73%) or supercritical carbon dioxide extract (15.73% at 400 bar, $30^{\circ}C$) at concentration of 10 mg/mL. However, SOD-like activities and TPCs were the highest in the supercritical carbon dioxide extract. At concentration of 1 mg/mL, supercritical carbon dioxide extract (22.54% at 200 bar, $40^{\circ}C$) was higher SOD activity than water (7.85%) and ethanol extract (6.12%). Regarding TPCs of MS extracts, the content was the highest in supercritical carbon dioxide extract (17.57 wt% catechin equivalent at 200 bar, $50^{\circ}C$) followed by ethanol and water extract. These results suggest that it can be useful to develop functional foods using antioxidative active compounds of MS with high polyphenol contents.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.609-613
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• 2005

Daidzein and genistein were extracted from Korean soybean by supercritical $CO_2$ and sub/supercritical water. The extracted sample was analyzed by reversed-phase high performance liquid chromatography (RP-HPLC). The retention time, retention factor, column efficiency, column selectivity and resolution of aglycons were compared with the change in the temperature and pressure of supercritical fluid and ethanol concentration. The characteristics of extraction of daidzein and genistein were more affected by ethanol concentration using supercritical $CO_2$. The most desirable extraction yield was obtained by supercritical $H_2O$ with $400^{\circ}C$ and 250 bar. Generally, the extraction yield of aglycons increased over 10 times using supercritical $CO_2$ than sub/supercritical $H_2O$.

• Textile Coloration and Finishing
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• v.31 no.1
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• pp.48-64
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• 2019

With evolution in the production environment of the textile industry, the need for non-water-based dyeing technologies and eco-friendly process facilities in the dyeing and processing stages has increased. In recent years, supercritical fluid dyes have been developed and commercialized in Europe, centering on this demand. However, so far, such dyes have been mainly applied in the processing of PET fibers. Basic research has mainly involved investigation of dyeing by supercritical carbon dioxide or solubility of such dyes, and more in-depth research should be continuously carried out. In this review, we describe the types and characteristics of supercritical fluids that exhibit specific properties at pressures and temperatures over the critical point. In addition, the state of the art in the dyeing and processing technology using supercritical fluids and associated, processing problems, environmental regulation, and wastewater treatment issues are described in detail. We hope this review can contribute to the supercritical fluid technology being further developed as an environment friendly dyeing processing method. Furthermore, we expect that the technique can be used as a means of ensuring different, high-quality dyed products.