• Journal of Mechanical Science and Technology
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• v.14 no.5
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• pp.553-561
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• 2000

This paper presents a numerical model of multi phase flow of the mixtures of molten material-liquid-vapor, particularly in thermal nonequilibrium. It is a two-dimensional, transient, three-fluid model in Eulerian coordinates. The equations are solved numerically using the finite difference method that implicitly couples the rates of phase changes, momentum, and energy exchange to determine the pressure, density, and velocity fields. To examine the model's ability to predict an experimental data, calculations have been performed for tests of pouring hot particles and molten material into a water pool. The predictions show good agreement with the experimental data. It appears, however, that the interfacial heat transfer and breakup of molten material need improved models that can be applied to such high temperature, high pressure, multi phase flow conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.176-186
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• 1996

The phenomena of drag reduction using small quantities of a liner macromolecules has attracted the attention of many experimental investigations. On the other hand drag reduction in two phase flow can be applied to the transport of crude oil, phase change system such as chemical reactor, pool and boiling flow, and to flow with cavitation which occurs pump impellers. But the research on dragreduction in two phase flow is not sufficient. The purpose of the present work is to evaluate the drag reduction by measuring pressure drop, void fraction, mean liquid velocity and turbulent intensity whether polymer additives a horizontal single and two phase system or not. Flow pattern of air-water two phase flow was classified by electrical conductivity probe signal. Velocities and turbulent intensities of signal were measured simultaneously with a Hot-film anemometer.

• Journal of Applied Biological Chemistry
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• v.44 no.2
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• pp.77-83
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• 2001

For defining the possibilities of the commercial mass liquid culture of Cordyceps sinensis, the pharmacological activities of mycelia were analyzed. The mycelium of C. sinensis consists of carbohydrate (5.1%) and fat (1.3%), and contains a low content of protein (0.7%) and ash (0.5%), and 92.4% moisture. The molecular sugar ratio of carbohydrate was composed mainly of glucose, mannose (1.0 : 0.9), in addition a small amount of galactose and arabinose (0.2 : 0.1). The cellular materials of mycelia were fractionated into ethylacetate (EA), MeOH (M) and hot-water extract fraction (HW). HW fraction showed the most potent intestinal immune system modulating activity, anti-coagulant activity, and anti-complementary activity, and M fraction had the inhibition activity of radical generation as effective as genistine. These results reveal that the mycelium of liquid cultured C. sinensis showed pharmacological activities and could be used for commercial purpose.

• Mycobiology
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• v.38 no.4
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• pp.295-301
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• 2010

We evaluated the antioxidant activity and tyrosinase inhibitory effects of Pleurotus ostreatus fruiting bodies extracted with acetone, methanol, and hot water. The antioxidant activities were tested against $\beta$-carotene-linoleic acid, reducing power, 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity, and ferrous chelating ability. Furthermore, phenolic acid and flavonoid contents were also analyzed. The methanol extract showed the strongest $\beta$-carotene-linoleic acid inhibition as compared to the other exracts. The acetone extract (8 mg/mL) showed a significantly high reducing power of 1.54 than the other extracts. The acetone extract was more effective than other extracts for scavenging on 1,1-diphenyl-2-picrylhydrazyl radicals. The strongest chelating effect (85.66%) was obtained from the acetone extract at 1.0 mg/mL. The antioxidant activities of the extracts from the P. ostreatus fruiting bodies increased with increasing concentration. A high performance liquid chromatography analysis detected seven phenolic compounds, including gallic acid, protocatechuic acid, chlorogenic acid, naringenin, hesperetin, formononetin, and biochanin-A in an acetonitrile and 0.1 N hydrochloric acid (5 : 1) solvent extract. The total phenolic compound concentration was $188{\mu}g$/g. Tyrosinase inhibition of the acetone, methanol, and hot water P. ostreatus extracts increased with increasing concentration. The results revealed that the methanol extract had good tyrosinase inhibitory ability, whereas the acetone and hot water extracts showed moderate activity at the concentrations tested. The results suggested that P. ostreatus may have potential as a natural antioxidant.

• Food Science and Biotechnology
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• v.18 no.3
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• pp.766-770
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• 2009

Hot water extracts of Camellia japonica flower buds were found to have the higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than the other solvent extracts. Five phenolic compounds were isolated and purified from the ethyl acetate soluble-neutral fraction of hot water extracts by Sephadex LH-20 column chromatography and octadecyl silane-high performance liquid chromatography using the guided assay of DPPH radical scavenging. Based on mass spectrometer and nuclear magnetic resonance, the isolated compounds were identified as p-hydroxybenzaldehyde (1), vanillin (2), dehydroxysynapyl alcohol (3), 7S,7'S,8R,8'R-icariol $A_2$ (4), and (-)-epicatechin (5). Four compounds (1-4) except for 5 were newly identified in this plant. Their DPPH radical scavenging activities as 50% scavenging concentration decreased in order to 5 $(20\;{\mu}M)>{\alpha}-tocopherol$ $(29\;{\mu}M)>4$ $(67\;{\mu}M)>3$ $(72\;{\mu}M)>1=2$ ($>250\;{\mu}M$). These results indicate that the antioxidant effect of the hot water extract of C. japonica flower buds may partially due to 5 isolated phenolic compounds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3403-3409
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• 2014

Hot-firing tests were carried out using a mixing head with 19 swirl coaxial injectors and a combustion chamber with internal cooling channels. The propellants of liquid oxygen and kerosene(Jet A-1) were burned in a range of chamber pressures (59~82 bar) and mixture ratios (2.0~3.0). The temperature of water used as the cooling fluid was measured at the inlet and outlet of the cooling channels, and the heat flux was calculated. The aim of this study was to examine the effect of combustion instability on heat transfer in a subscale thrust chamber, and detect the temperature variation of cooling water. During several hot-firing tests, combustion instability was encountered which caused a 5~20% increase in heat flux. The peak heat flux took place in the initial stages of combustion instability.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.10-17
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• 2004

The results of the combustion performance tests of gas generator which supplies hot gas into the turbine of turbo-pump for liquid rocket engine and uses LOx and kerosene as propellant are described. The gas generator consists of a injector head with F-O-F impinging injector, a water cooled combustion chamber, a gas torch igniter, a turbulence ring and an instrument ring. The effect of turbulence ring and combustion chamber length on performance of gas generator are investigated. The ignition and combustion at design point are stable and the pressure and gas temperature at gas generator exit meets the target. The turbulence ring installed at middle of chamber effectively mixes hot gas with cold gas and the effect of residence time of hot gas in gas generator on combustion efficiency is small. Test results show that the main parameter controlling the gas temperature at gas generator exit is overall O/F ratio.

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.61-68
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• 2004

The evaporation phenomena of waterr droplet which has sodium acetate trihydrate($CH_3COONa{\cdot}3H_2O$) as a fire suppression additive were studied. Solutions of sodium salt up to 50% and heated stainless-steel surface were used in the experiment. The evaporation process was recorded using a charge-coupled-device camera at 120 frames per second. The average evaporation rate of the sodium acetate trihydrate soluation was lower than that of pure water at a given surface temperature and decreased with the concentration increase due to the precipitation of salt in the liquid film and change of surface tension. The variation of liquied film diameter was measured by time and it was increased by the hot surface temperature increase.

• Journal of Pharmacopuncture
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• v.16 no.2
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• pp.33-40
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• 2013

Objective: This study was conducted to investigate the amino-acid compositions of pharmacopuncture extracts taken from the body and from the tail of Buthus martensii Karsch, which are frequently prescribed in Oriental medicine. Methods: Amino acids in hot water and 70% ethanol extracts taken from the scorpion's whole body and from its tail were screened by using high performance liquid chromatography (HPLC). The experiments were performed with linearity, precision and accuracy. Results: The results of the amino-acid-composition analysis showed that the Buthus martensii Karsch extracts contained various amino acids such as aspartic acid, histidine, alanine, tyrosine, and cystine. The amino-acid analysis showed that the hot water extract was more beneficial than the ethanol extract, except for histidine. The amino acids from the tail and the body of the scorpion were compared, and the concentration of aspartic acid in the extract from the scorpion's tail was two times that found in the extract from its body. The results of validation experiments were all satisfactory. Conclusion: Studies on the ingredients in extracts from a scorpion other than buthotoxin may demonstrate that the antiepileptic efficacy, anticancer activity, anti-thrombotic action and analgesic effect are enhanced. Using only the tail of the scorpion when pharmacopuncture is dispensed may be beneficial because the extracts from the tail of the scorpion have higher potency than those from the whole body.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.786-793
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• 1999

To investigate the effects of medicinal plants on the shelf life of kakdugi, various kakdugies, added with hot water extract from 62 natural plants, were fermented at 20oC for 15 days. In case of control without the addition, the shelf life required to reach the acidity of 1%(as lactic acid) was 7 days. Morethan two fold extension of shelf life was observed with twenty seven extracts, of which six extracts maintained the hardness of kakdugi higher than that of control over the entire fermentation time. And the number of lactic acid bacteria in above kakdugies was not remarkably different from that of control, and the color(a value) of the liquid of kakdugi, added with Chaenomeles lagenaria, Moringa oleifera, Peaonia lactiflora or Citrus tangerina extract, was similar to that of control. In sensory test, the extracts from the above plants except Moringa oleifera were found to be acceptable. It is suggested that the addition of above three extracts may lead to extension of shelf life of kakdugi, based on the acidity, hardness, color and sensory test.