• Korean Journal of Agricultural Science
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• v.22 no.2
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• pp.134-142
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• 1995

In order to elevate the efficiency of methane fermentation using the paper mill sludge, this experiment was conducted at two temperature conditions($35^{\circ}C$ and $60^{\circ}C$), and overlooked the addition effects of ethyl acetate as a substrate, nickel as a constituent of $F_430$, and sulfur as a cell growth factor and reductant. The cellulose of paper mill sludge was degraded to lower molecular materials by heating at $60^{\circ}C$ and NaOH treatment. Methane forming rates were 4.8% from NaOH-treated paper mill sludge added with ethyl acetate, 16.5% with sodium sulfide, 19.8% with nickel trioxide, 31.9% with mixture, and 9.6% with control at $60^{\circ}C$, but 0.21% with ethyl acetate, 2.14% with nickel acetate, 3.02% with nickel sulfate, 3.34% with nickel trioxide and 0.62% with control at $35^{\circ}C$. Therefore, methane yield was increased by approximately 10-fold at $60^{\circ}C$ than $35^{\circ}C$, and fermentation liquid added with mixture(nickel trioxide+ethyl acetate+sodium sulfide) at $60^{\circ}C$ showed the medium pH(7.0), higher COD value and lower nitrogen content.

• Journal of the Korean Solar Energy Society
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• v.36 no.3
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• pp.53-61
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• 2016

Solar assisted heat pump system uses solar thermal energy as a heat source of evaporator of heat pump. So, COP can be enhanced as well as collector efficiency. For improving performance of this system, some research about hybrid solar collector that has fin-and-tube heat exchanger has been conducted. This collector can get a thermal energy from ambient air for liquid heating, so heated liquid can be used as a heat source of evaporator in heat pump even the solar radiation is not enough. In this study, numerical analysis was conducted for confirming heat gain of liquid according to fin height and pitch of fin-and-tube heat exchanger in collector. As a result, higher heat gain was obtained on lower fin height and narrow fin pitch, but the pressure drop also increased with increment of heat gain. Thus the JF factor considering both heat transfer enhancement and pressure drop was investigated and the maximum value was shown when the fin height and pitch were 40mm and 45mm. So it is considered that this installation condition has a highest heat transfer improvement when comparing with pressure drop. However heat gain of liquid at this condition was less than the other installation conditions of fin pitch on same height. Then, after establishing a proper minimum heat gain of liquid, actual production and experiment of collector will be conducted with fin height and pitch showing maximum JF factor and satisfying selected minimum heat gain of liquid on the basis of results of this study.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.249-257
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• 1991

To elucidate enzymatic properties of ${\alpha}-galactosidase$ (EC 3, 2, 1, 22) from germinated soybean, changes in the enzyme activities and oligosaccharide contents during germination of soybean were determined. ${\alpha}-Galactosidase$ from germinated soybean was purified by ammonium sulfate fractionation, ion exchange chromatography and gel filtration. Their chemical and enzymatic properties was investigated. ${\alpha}-galactosidase$ activity of sobeam was maximized when it was germinated at $25^{\circ}C$ for 120 hour. Raffinose and stachyose in soybean were decomposed completely after 96 hours and 120 hours of germination, respectively. Soybean ${\alpha}-galactosidase$ was purified by 6.6 fold by ammonium sulfate fractionation, ion exchange chromatography on DEAE-Cellulose and Sephadex A-50, and gel filtration on Sephadex G-150. Its specific activity was 825 Units/mg protein and the yield was 2.5% of the total activity of crude extracts. The purified ${\alpha}-galactosidase$ of soybean was found to be homogeneous by polyacrylamide gel electrophoresis and by HPLC. Isoelectric point of soybean ${\alpha}-galactosidase$ was determined analytical isoelectric focusing to be pH 4.8. The soybean ${\alpha}-galactosidase$ was monomeric and its molecular weight was estimated to be 30,000 by SDS-PAGE. The optimal temperature and pH for the soybeam ${\alpha}-galactosidase$ activity were $40^{\circ}C$ and pH 6.0 and 75% of its activity was lost by heating at $60^{\circ}C$ for 10 min. The enzyme was appeared to have higher affinity to raffinose than to stachyose. The Km value of soybean enzyme was 5.3 mM for ${\rho}-nitrophenyl-{\alpha}-D-galactopyranoside$ and the activation energy on PNPG was calculated to be 13.02 Kcal per mole.

• Clean Technology
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• v.22 no.4
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• pp.286-291
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• 2016

In this study we made fuel pellet from miscanthus biomass and investigated changes of physiological characteristics and electricity consumption of pelletizing process in comparison with fuel pellet made of pine sawdust. We also examined combustion characteristics including ash content and clinker forming ratio with fuel pellet made of mixing with micanthus biomass and lime powder. Bulk density of ground-miscanthus and pine sawdust were $158g\;L^{-1}$ and $187g\;L^{-1}$, respectively. Bulk density of ground miscanthus was lower than that of pine sawdust, but increased to $653g\;L^{-1}$ after pelletizing, which was similar to $656g\;L^{-1}$ of pine sawdust pellet. Moisture content in raw miscanthus and ground miscanthus were 17.0% and 11.8%, respectively. Moisture content in ground miscanthus was similar to that of pine saw dust and decreased to 6.73% after pelletizing, which was 7.7% lower than that of pine sawdust pellet. Although $27kWh\;ton^{-1}$ were required for compaction press that was an additional process in miscanthus pelleitizing, total required electricity was $193kWh\;ton^{-1}$ which was similar to $195kWh\;ton^{-1}$ of pine sawdust pellet pelleitizing. Pellet durability and pelletizing ratio of miscanthus were 98.0% and 99.7%, respectively, which were similar to 98.1% and 99.4% of pine sawdust pellet. When lime mixing ratio increased, ash melting degree and clinker forming ratio of miscanthus pellet increased. While higher heating value and clinker forming ratio of miscanthus pellet decreased.

• Clean Technology
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• v.24 no.4
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• pp.323-331
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• 2018

The results of an experimental investigation on the co-firing characteristics and slagging behavior of dried and hydrothermal carbonization sewage sludge, sub-bituminous coal, and wood pellet in a fluidized bed were presented. Combustion tests were conducted in a lab-scale bubbling fluidized bed system at the uniform fuel-air equivalence ratio, air flow rate, and initial bed temperature to measure bed temperature distribution and combustion gas composition. 4 different fuel blending cases were prepared by mixing sewage sludge fuels with coal and wood pellet with the ratio of 50 : 50 by the heating value. $NO_x$ was mostly NO than $NO_2$ and measured in the range of 400 to 600 ppm in all cases. $SO_2$ was considered to be affected mostly by the sulfur content of the sewage sludge fuels. The cases of hydrothermal carbonization sewage sludge mixture showed slightly less $SO_2$ emission but higher fuel-N conversion than the dried sewage sludge mixing cases. The result of fly ash composition analysis implied that the sewage sludge fuels would increase the possibility of slagging/fouling considering the contents of alkali species, such as Na, K, P. Between the two different sewage sludge fuels, dried sewage sludge fuel was expected to have the more severe impact on slagging/fouling behavior than hydrothermal carbonization sewage sludge fuel.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.429-432
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• 2011

The feasibility of applications of the char obtained from a gasification process of municipal-waste refuse derived fuel (RDF) as an auxiliary fuel was evaluated by combustion experiments. The higher heating value of the RDF char was 3000~4000 kcal/kg and its chlorine content was below the standard requirement demonstrating its potential as an auxiliary fuel. In the combustion exhaust gas, the maximum $NO_x$ and $SO_2$ concentrations were 240 ppm and 223 ppm, respectively. If an aftertreatment is applied, it is possible to control their concentrations low enough to meet the air pollutant emission standard. The HCl concentration was relatively high indicating that a care should be taken for HCl emission from the combustion of RDF. Based on the temperature distribution within the reactor, the concentration change of $O_2$ and $CO_2$, and the amount and the loss on ignition of solid residue, it was inferred that the combustion reaction was the most reliable when the excess air ratio of 1.3 was used.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.28-37
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• 2022

The lignite and bituminous coal are mainly used in thermal power plant. They exhaust green house gas (GHG) such as CO₂, and become deplete, thus require alternative energy resources. To solve the problem, the hydrochar production from biomass is suggested. In this study, both hydrothermal carbonization (HTC) and solvothermal carbonization (STC) were used to produce high quality hydrochar. To improve the reactivity of water solvent process in HTC, STC process was conducted using ethanol solution. The experiments were carried out by varying the solid-liquid ratio (1:4, 1:8, 1:12), reaction temperature (150~300 ℃) and retention time (15~120 min) using kenaf. The characteristic of hydrochar was analyzed by EA, FT-IR, TGA and SEM. The carbon content of hydrochar increased up to 48.11%, while the volatile matter decreased up to 39.34%. Additionally, the fuel characteristic of hydrochar was enhanced by reaction temperature. The results showed that the kenaf converted to a fuel by HTC and STC process, which can be used as an alternative energy source of coal.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.635-641
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• 2003

A non-thermal pasteurization technology, high Pulsed Electric Field (PEF) has been thought to be a new alternative processing technology instead of heating. The objective of this study was to examine and compare the effect of PEF and High Temperature Short Time (HTST) treatments on the physicochemical, microbiological and sensory characteristics of citrus juices. Total sugar and titratable acidity values of fresh citrus juice and two treatments were not significantly different each other at p<0.05. The concentration of vitamin C in fresh citrus juice $(31.2{\pm}0.59\;mg%)$ was not significantly different with the value of PEF treatment $(29.4{\pm}0.75\;mg%)$ but was significantly higher than the value of HTST treatment $(27.4{\pm}0.75\;mg%)$. The color values (L, a, and b) in PEF treatment were significantly lower than the fresh citrus juice, but were higher than the values of HTST treatment. Both total bacterial cell counts $(6.65\;{\pm}\;0.08\;log_{10}(cfu/mL))$ and yeast counts $(7.79{\pm}0.07\;log_{10}(cfu/mL))$ in fresh citrus juice were significantly reduced by PEF $(1.39{\pm}0.14,\;2.42{\pm}0.1\;log_{10}(cfu/mL))$ as well as HTST treatment (0, 0). PE activity of fresh citrus juice $(1.3{\pm}0.12\;units/mL)$ was significantly reduced by PEF treatment $(0.11{\pm}0.01\;units/mL)$ and was totally inactivated by HTST treatment. Sensory evaluation scores in flavor, taste and overall acceptability between the fresh and PEF treated citrus juices $(7.2{\sim}7.5)$ were not significantly different but the values of HTST treatment $(5.1{\sim}5.8)$ were lower than others. Consequently, PEF treatment is thought to be a good alternative pasteurization method for fresh citrus juice to HTST treatment due to its strong pasteurization effect, reduced destruction of nutrients and good sensory characteristics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.4
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• pp.569-576
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• 2016

This study researched the effects of cooking methods on phytochemical-enriched thin rice porridge (RP) of three colors (red, yellow, and green). Each of the RPs was prepared by three cooking methods and retorted through two-steps (step 1, at $80^{\circ}C$ for 15 min; step 2, at $82^{\circ}C$ for 25 min) for pasteurization. Cooking method (CM) 1 involved heating a mixture of all ingredients while CM 2 involved addition of apple/beet (AB, red), sweet-pumpkin/cabbage (PC, yellow) or vitamin/pear (green) while heating rice flour and glutinous rice flour. CM 3 involved mixing pre-cooked fruits and vegetables with cooked thin RP. The viscosity of RP prepared by CM 1 was lower than those of other RPs (P<0.05). The result of colorimetric a value show that red and green color of AB and VP prepared by CM 2 and CM 3 were most vivid. Contents of phytochemicals and antioxidants were higher when RP was prepared by CM 2 and CM 3 compared to CM 1. ${\Delta}E$ values of PC showed no significant difference before and after pasteurization, whereas AB and VP were significantly different (P<0.05). Antioxidant activity after retorting was not significantly different from those of un-retorted RPs. The results of color, phytochemical content, and antioxidant activity show that CM 2 or CM 3 were considerably better than CM 1, whereas cooking method had no effect after two-step retorting. Therefore, uncomplicated cooking method such as CM 1 or CM 2 are suited for commercial production of RPs.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.2 s.38
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• pp.77-87
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• 1991

The purpose of this study were to investigate the bed climate and the physiological responses in sleep on the traditional Korean floor heating system called Ondol. Ondol has been the most widely used heating system in Korea, yet there has been a no systematic studies examined its environmental effects on human body. Experimental room was constructed to match the typical thermal environment of Ondol. (floor surface temperature; $32\~33^{\circ}C$, air temperature; $22.5{\pm}1.0^{\circ}C$, relative humidity; $64.0{\pm}4.0\%$RH, air velocity; 0.25 m/sec.) Three different combinations of bedclothes were chosen for the experiment based on the study results showing that they were the most widely used types in Korea. Type 1 was the combination of a cotton-padded mattress with a cotton-padded Korean style blanket. Type 2 was a cotton-padded mattress with a cotton-guilted Korean style blanket. Type 3 was a cotton-padded matless with a polyacryl blanket. Thermal resistance of each of these combina-tions in the bedclothes was measured using thermal manikin. Two adult female was chosen for the seven hour sleeping experiment which was known to be the average sleeping hours of Korean adult female. The bed climate was measured with the temperature under the mattress, the surface temper-ature of the mattress, and the air temperature and the relative humidity of the space between the mattress and blanket. The skin temperature, rectal temperature of the subjects and the bed climate were measured eight times, one hour before the experiment and every hour during the experiment. The weight loss and the subjective sensation were measured for the each subjects before and after the experiment. The procedure was repeated twice with two subjects and three types of bedclothes, yielding twelve combinations of results. The results were as follows; 1. With the surface temperature of $32\~33^{\circ}C$ of Ondol, air temperature was $22.5{\pm}1.0^{\circ}C$ with $64.0{\pm}4.0\%$ RH. The bed climates were $39.2{\pm}40.8^{\circ}C$ under the mattress, $35.3\~36.2^{\circ}C$ on the mattress, and $26.9\~32.0^{\circ}C$ with $56.0\~71.3\%$ RH between the mattress and the blanket. 2. Mean skim temperature during sleep was 34.2"C with local skin temperature of $34.0\~35.5^{\circ}C$. The skin temperatures of abdomen, thigh, foot were higher than the other parts of the body. 3. The skin temperature of chest, thigh, leg and back varied significantly according to the combinations of bedclothes. With the cotton-padded blanket, the skin temperature was the highest, while with the cotton-guilted blanket showed lowest. 4. Examining the relationship between the mean skin temperature and the local skin temper-ature, the chest temperature showed the highest correlation with the former. Therefore, the chest temperature can be recommended to represent the skin temperature in measuring the bed climate. 5. The subjective bed climates were $39.0\~40.4^{\circ}C$ under the mattress, $35.2\~35.9^{\circ}C$ on the mattress, $29.8\~31.6^{\circ}C$ with $56.8\~68.4\%$ RH between the mattress and blanket. In sum, from this experiment we not only obtained the reliable value of bed climates on Ondol, but also showed that the bed climates and the physiological responses were affected differently according to the materials of bed clothes.