• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.7
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• pp.938-944
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• 2000

Recently, micro fin tube is widely used to heat exchanger for high performance. And, as the alternative refrigerants for R-22, hydrocarbons such as R-290, R-600 and R-600a are very promising because of their low GWP and ODP. Thus, R-290 was used as working fluid in this study. Most design of heat exchanger had been based on heat transfer characteristics of pure refrigerant although refrigerant oil exists in the refrigeration cycles. So, the influence of oil on heat transfer characteristics have to be considered for investigating exact evaporation heat transfer characteristics. But, this is an unresolved problem of refrigeration heat transfer. Therefore the influence of the refrigeration oil to the evaporation heat transfer characteristics of R-290 were conducted in a horizontal micro tin tube. The mineral oil was used as refrigeration oil. The experimental apparatus consisted of a basic refrigeration cycle and a system for oil concentration measurement. Test conditions are as the follows; evaporation temperature $5^{\circ}C$, mass velocity 100 $kg/m^2s$, heat flux 10 $kW/m^2$, oil concentration 0, 1.3, 3.3, 5.7 wt.%, and quality $0.07{\sim}1.0$. When refrigeration oil was entered, oil foaming was observed at the low quality region. And, very small bubbles were observed as quality was increased. Pressure drop and heat transfer coefficient increased as the concentration of refrigeration oil increased to 5 wt.%.. The performance index of heat exchanger was the highest near 3.3 wt.%.

• Journal of Adhesion and Interface
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• v.13 no.4
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• pp.163-170
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• 2012

Although ${\beta}$-cyclodextrin (${\beta}$-CD) has been used as medicine, agrichemical, food, cosmetic, antioxidant, anti-volatile agent, anti-hygroscopic agent, fading-protecting agent, and emulsifier due to its ability to form inclusion complex by enclosing another molecule (guest molecule), it has been restricted in practical application because of its low solubility in water and organic solvent. In this study, ${\beta}$-CD derivative as a new polyol with inclusion characteristics against Bisphenol A and cyclopropane, foaming agent for polyurethane (PU), and with improved solubility was synthesized, characterized and used to formulate rigid PU foam with better thermal conductivity and compressive strength compared to that from commercial polyols.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.61-70
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• 2012

Recently, the government has been working feverously to save energy and reduce greenhouse gas emission by enacting Basic Act on Low Carbon Green Growth at the national level. Improving the insulation performance of building exterior and insulator can reduce the energy in the building sector. This study is about developing light-weight foamed concrete insulation panel that can be applied to buildings to save energy and to find the optimal condition for the development of insulation materials that can save energy by enhancing its physical, kinetic and thermal characteristics. Various experimental factors and conditions were considered in the study such as foam agent types (AES=Alcohol Ethoxy Sulfate, AOS=Alpha-Olefin Sulfonate, VS=Vegetable Soap, FP=Fe-Protein), foam agent dilution concentration (1, 3, 5%), and foam percentage (30, 50, 70%). Experiment results indicated that the surface tension of aqueous solution including foam agent, was lower when AOS was used over other foam agents. FP produced relatively stable foams in 3% or more, which produced unstable foams containing high water content and low surface tension when diluted at low concentration. Depending on foam agent types, compressive strength and thermal conductivity were similar at low density range but showed some differences at high concentration range. In addition, when concentrations of foam agent and foaming ratio increased, pore size increased and open pores are formed. In all types of foam agent, thermal conductivity were excellent, satisfying KS standards. The most outstanding performance for insulation panel was obtained when FP 3% was used.

• Food Science of Animal Resources
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• v.37 no.2
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• pp.228-241
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• 2017

Hematological, chemical and functional characteristics of porcine, chicken and duck blood were evaluated. A porcine blood sample showed the most abundant red blood cell, hemoglobin concentration, packed cell volume and plasma protein content as well as its freeze-dried blood possessed the highest contents of protein, fat, Cu and Cr with the highest percentage of heme iron (p<0.05). Unlike porcine blood, chicken blood showed a well balance in some essential amino acids, specifically for a higher isoleucine content (p<0.05). Furthermore, it possessed the highest contents of carbohydrate, Zn and non-heme iron (p<0.05). The most rapid response to form a strong gel, especially at $70^{\circ}C$ and $80^{\circ}C$, was found in chicken blood, followed by duck and porcine blood, respectively. The result of emulsion activity index (EAI) and emulsion stability index (ESI) at the low protein concentration indicated that chicken blood had the most superior emulsion properties (p<0.05). Regarding duck blood, it exhibited the highest content of Mg and Mn (p<0.05). Moreover, duck blood had similar foaming properties to porcine blood in which they showed higher values than chicken blood (p<0.05). Specific characteristics of blood were therefore diminished by animal species in which this information could be used as food supplementation or product development based on their potential applications.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.530-536
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• 1993

Acidic degreasing agent(ADA) was prepared by blending n-octanoic acid, MJU-100A, Tetronix T-701, POE(6)-2-ethylhexyl ether, Newpol PE-68, sorbitol, and phosphoric acid. The physical properties of ADA tested with aluminum specimen showed the following results; when 3wt% ADA-5 was performed at $70^{\circ}C$, the degreasing rate was 98% which is comparitively good, and the percentage of etching was 0.277% which was found to be less than that of commercialized product. When 20wt% of ADA-5 was added at $65^{\circ}C$, the percentage of derusting was 93% and the good defoaming effect proved by following low foaming power tests respectively : Ross and Miles, and Ross and Clark methods.

• Food Science of Animal Resources
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• v.37 no.1
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• pp.29-37
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• 2017

Defatted bovine liver (DBL) is a potential source of protein and minerals. Supercritical carbon dioxide ($SC-CO_2$) and a traditional organic solvent method were used to remove lipid from bovine liver, and the quality characteristics of a control bovine liver (CBL), bovine liver defatted by $SC-CO_2$ ($DBLSC-CO_2$) at different pressures, and bovine liver defatted by organic solvent (DBL-OS) were compared. The $DBLSC-CO_2$ samples had significantly higher (p<0.05) protein, amino acid, carbohydrate, and fiber contents than CBL and DBL-OS. There was a higher yield of lipid from CBL when using $SC-CO_2$ than the organic solvent method. SDS-PAGE analysis demonstrated that the CBL and $DBLSC-CO_2$ had protein bands of a similar intensity and area, whereas DBL-OS appeared extremely poor bands or no bands due to the degradation of proteins, particularly in the 50 to 75 kDa and 20 to 25 kDa molecular weight ranges. In addition, $DBLSC-CO_2$ was shown to have superior functional properties in terms of total soluble content, water and oil absorption, and foaming and emulsification properties. Therefore, $SC-CO_2$ treatment offers a nutritionally and environmentally friendly approach for the removal of lipid from high protein food sources. In addition, $SC-CO_2$ may be a better substitute of traditional organic solvent extraction for producing more stable and high quality foods with high-protein, fat-free, and low calorie contents.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.66-70
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• 2014

The superconducting fault current limiter (SFCL) is an electrical power system device that detects the fault current automatically and limits the magnitude of the current below a certain safety level. The SFCL module does not have any electrical resistance below the critical temperature, which facilitates lossless power transmission in the electric power system. Once given the fault current, however, the superconducting conductor exhibits extremely high electrical resistance, and the magnitude of the current is accordingly limited to a low value. Therefore, SFCL should be maintained at a temperature below the critical temperature, which justifies the cryogenic cooling system as a mandatory component. This report is a study which reported on the cooling system for the 154 kV-class hybrid SFCL owned by Korea Electric Power Corporation (KEPCO). Using the cryocooler, the temperature of liquid nitrogen (LN2) was lowered to 71 K. The cryostat was pressurized to 5 bars to improve the dielectric strength of nitrogen and suppress nitrogen bubble foaming during operation of SFCL. The SFCL module was immersed in the liquid nitrogen of the cryostat to maintain the superconducting state. The performance test results of the key components such as cryocooler, LN2 circulation pump, cold box, and pressure builder are shown in this paper.

• Korean journal of food and cookery science
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• v.6 no.3 s.12
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• pp.9-15
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• 1990

Peanut prptein isolate was tested for the purpose of finding out the effect of pH, Sodium Chloride concentration and heat treatment on the solubility, surface hydrophobicity, foam expansion and foam stability. The solubility of peanut protein isolate was affected by pH and showed the lowest value at pH 4.5. When the peanut protein isolate was heated, the solubility decreased at pH 3 and pH 7 but at pH 9 solubility increased. At all pH range, solubility decreased as NaCl was added. The surface hydrophobicity of peanut protein isolate showed the highest value at pH 1.5. Generally, at acidic pH range the surface hydrophobicity was high, but at alkaline region, the surface hydrophobicity increased as the temperature increased. And when NaCl was added, the surface hydrophobicity was also increased. Foam expansion of peanut protein isolate was no significant difference among the values about pH. When the peanut protein was heated and NaCl was added, foam expansion was increased at pH 7. Foam stability was significantly low at pH 4.5 and foam stability was increased at acidic pH region below pH 4.5. At pH 7 and pH 9, heat treatment above $60^{\circ}C$ increased foam stability. When NaCl was added, foam stability was significantly increased at pH 3 and pH 7.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.551-558
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• 1991

We investigated the physicochemical and functinal properties of rapeseed(Brassica napus var. Youngsan) protein prepared by combining various soluvent and purification procedures, such as ultrafiltration (UF) concentration and acid-washin. The lightness value(YCIE) of each protein was greadully improved and its hydrophobicity increased by the degree of purification. The analysis of each protein by sodium dodecyl sulfate-plyacrylamide gel electrophoresis (SDS-PAGE) had nine bands revealed without difference, the considerable portion of which were of $1.96~1.59{\times}10^4$ dalton molecular weight. The content of amino acid increased a little more in the other processed proteins than in the control, and decreased considerably in the proteins extracted by the mixed solvent of 1% sodium hexametaphosphate(SHMP) and 0.25M ethlene diamine tetraacetic acid (EDTA). The better proteins were purified, the lower the kinematic viscosities were in their values. The water absorption and foaming properties were scarcely different according to the processes. The oil absorption and the emulsion activity index normally increased according to the degree of purification. The properties of heat coagulation revealed high values only in the proteins processed by EDTA while they showed considerably low values the other proteins.

• Membrane Journal
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• v.15 no.3
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• pp.187-197
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• 2005

A membrane contactor is a device that achieves liquid/liquid or gas/liquid mass transfer without dispersion of one phase within another. This is accomplished by passing the fluids on opposite sides of a microporous membrane. This approach offers a number of important advantages over conventional dispersed phase contactors, including absence of emulsions, no flooding at high flow rates, no unloading at low flow rates, and high interfacial area. This article provides a general review of membrane contactors, including operating principles and applications.