• Korean Journal of Environmental Agriculture
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• v.35 no.2
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• pp.128-136
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• 2016

BACKGROUND: Hydrothermal carbonization reaction is the thermo-chemical energy conversion technology for producing the solid fuel of high carbon density from organic wastes. The hydrothermal carbonization reaction is accompanied by the thermal hydrolysis reaction which converse particulate organic matters to soluble forms (hydro-thermal hydrolysate). Recently, hydrothermal carbonization is adopted as a pre-treatment technology to improve anaerobic digestion efficiency. This research was carried out to assess the effects of hydro-thermal reaction temperature on the methane potential and anaerobic biodegradability in the thermal hydrolysate of organic sludge generating from the wastewater treatment plant of poultry slaughterhouse .METHODS AND RESULTS: Wastewater treatment sludge cake of poultry slaughterhouse was treated in the different hydro-thermal reaction temperature of 170, 180, 190, 200, and 220℃. Theoretical and experimental methane potential for each hydro-thermal hydrolysate were measured. Then, the organic substance fractions of hydro-thermal hydrolysate were characterized by the optimization of the parallel first order kinetics model. The increase of hydro-thermal reaction temperature from 170℃ to 220℃ caused the enhancement of hydrolysis efficiency. And the methane potential showed the maximum value of 0.381 Nm³ kg^-1-VS_added in the hydro-thermal reaction temperature of 190℃. Biodegradable volatile solid(VSB) content have accounted for 66.41% in 170℃, 72.70% in 180℃, 79.78% in 190℃, 67.05% in 200℃, and 70.31% in 220℃, respectively. The persistent VS content increased with hydro-thermal reaction temperature, which occupied 0.18% for 170℃, 2.96% for 180℃, 6.32% for 190℃, 17.52% for 200℃, and 20.55% for 220℃.CONCLUSION: Biodegradable volatile solid showed the highest amount in the hydro-thermal reaction temperature of 190℃, and then, the optimum hydro-thermal reaction temperature for organic sludge was assessed as 190℃ in the aspect of the methane production. The rise of hydro-thermal reaction temperature caused increase of persistent organic matter content.

• Journal of Powder Materials
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• v.22 no.5
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• pp.356-361
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• 2015

Fe-30 wt% TiC composite powders are fabricated by in situ reaction synthesis after planetary ball milling of (Fe, $TiH_2$, Carbon) powder mixture. Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe-30 wt% TiC composite powder compacts. Pressureless sintering is performed at 1100, 1200 and $1300^{\circ}C$ for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of $1050^{\circ}C$, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of $50^{\circ}C/min$, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts are not densified even after sintering at $1300^{\circ}C$ for 3 h, which shows a relative denstiy of 66.9%. Spark-plasma sintering at $1050^{\circ}C$ for 10 min exhibits nearly full densification of 99.6% relative density under the sintering pressure of 50 MPa.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.351-361
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• 2010

Among common estuarine submerged plants, seagrasses are the most extensively studied due to their ecological importance in estuarine ecosystems. Seagrass meadows are important biological habitats for a wide variety of marine animals and plants. They are a source of organic carbon for commercially important animals. Furthermore, seagrasses act as nutrient filters in estuarine and coastal marine ecosystems. As such, mapping the distribution of seagrass beds is important for management and conservation strategies. In order to survey the seagrass distribution within the Seomjin Estuary, We directly observed seagrass beds in Kwangyang and Hadong using SCUBA. The distribution area, species composition, morphology, density, biomass and productivity of seagrass meadows were examined. Seagrass meadows were distributed in the intertidal and subtidal zones of the Galsa tidal flats, and in the subtidal zone of the neighboring POSCO area. Patches of Zostera japonica was found at patches at the Galsa tidal flats intermediate point. The total estimated seagrass distribution area of the Seomjin Estuary was $1.84\;km^2$. Of the total, $1.83\;km^2$ was Zostera marina (eelgrass) and $0.01\;km^2$ was Zostera japonica (dwarf eelgrass). Zostera japonica was found in intertidal zones. Zostera marina was found from the intertidal to subtidal zones at a 2 m mean sea level (MSL) depth. The leaf productivity of Zostera marina was $4.47g\;DW\;m^{-2}\;day^{-1}$. The annual production of eelgrass was $1,632\;g\;DW\;m^{-2}\;yr^{-1}$, which corresponds to $731g\;C\;m^{-2}\;yr^{-1}$. The total production of eelgrass was $3,002\;tons\;DW\;yr^{-1}$, which corresponds to $1,343\;tons\;C\;yr^{-1}$.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.614-618
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• 1992

The batch and fed-batch cultivations of Brevibacteriurn CHI were carried out for the production of nitrile hydratase. In batch culture, with pH control the cell mass and the specific activity increased more 20% and 30%. respectively. The maximum growth rate was obtained at a glucose concentration of $20g/{\ell}$ because of substrate inhibition. The fed-batch culture of Brevibacteriurn CHI with constant substrate feeding gave a cell density of up to $68g/{\ell}$ and nitrile hydratase activity was maintained at above 6.1units/mg. The cell growth yield on carbon .source was ca. 0,68 g/g glucose consumed. The total nitrile hydratase activity in this fed-batch mode increased up to 414.8 units/m${\ell}$, which amounted to 4.4 times that of the batch culture.

• Elastomers and Composites
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• v.46 no.2
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• pp.138-143
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• 2011

EPDM compounds and vulcanizates containing inorganic filler such as talc, calcium carbonate, or clay as well as carbon black were prepared, and the influence of inorganic filler on properties of the EPDM compounds and vulcanizates were investigated. The bound rubber contents did not significantly increase even though the inorganic filler was added. There were big aggregates in the EPDM samples with high loading inorganic filler. By adding the inorganic filler, the cure times tended to increase and the delta torque decreased. The modulus were on the whole decreased, whereas the elongation at break, tensile strength, and tear strength were increased by adding the inorganic filler. The decreased modulus and increased elongation at break can be explained with the decreased delta torque, the increases of tensile strength and tear strength can be explained with the increased elongation at break. By adding the inorganic filler, level of reinforcing in the EPDM compounds did not increase and the crosslink density decreased.

• Mycobiology
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• v.38 no.4
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• pp.274-281
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• 2010

Cordyceps cardinalis was reported in Japan and the USA in 2004, and its fruiting bodies have recently been cultured in Korea. Herbarium specimens preserved at the Cordyceps Research Institute, Mushtech, Korea were revised and identified as C. cardinalis, based on morphological characters and conidial structures. Most of the C. cardinalis specimens were collected from Mt. Halla in Jeju-do. The effects of various nutritional sources and environmental conditions such as temperature and pH on mycelial growth of C. cardinalis were studied. Oatmeal agar, Martin's peptone dextrose agar, and Schizophyllum (mushroom) genetics complete medium plus yeast extract resulted in the best mycelial growth. Among carbon sources, cereals, and nitrogen sources, maltose, oatmeal, and peptone resulted in the best mycelial growth respectively. Mineral salts helped to increase growth rate but only resulted in thin mycelial density, similar to water agar. A temperature of $25^{\circ}C$ and a pH of 7 resulted in the highest mycelial growth. Based on these results, a Cordyceps cardinalis composite medium (CCM) was formulated with 1% maltose, 2% oatmeal, 1% peptone, and 2% agar. Use of the CCM resulted in slightly better mycelial growth than that of other commonly used agar media. Only organic nitrogen sources imparted a reddish pigmentation to the agar media, but this character diminished after several subcultures. A 7 day culture duration resulted in the best mycelial growth.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.774-780
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• 2019

The performance of Li-ion hybrid supercapacitors (asymmetric-type) depends on many factors such as the capacity ratio, material properties, cell designs and operating conditions. Among these, in consideration of balanced electrochemical reactions, the capacity ratio of the negative (anode) to positive (cathode) electrode is one of the most important factors to design the Li-ion hybrid supercapacitors for high energy storing performance. We assemble Li-ion hybrid supercapacitors using activated carbon (AC) as anode material, lithium manganese oxide as cathode material, and organic electrolyte (1 mol L^-1 LiPF₆ in acetonitrile). At this point, the thickness of the anode electrode is controlled at 160, 200, and 240 ㎛. Also, thickness of cathode electrode is fixed at 60 ㎛. Then, the effect of negative and positive electrode ratio on the electrochemical performance of AC/LiMn₂O₄ Li-ion hybrid supercapacitors is investigated, especially in the terms of capacity and cyclability at high current density. In this study, we demonstrate the relationship of capacity ratio between anode and cathode electrode, and the excellent electrochemical performance of AC/LiMn₂O₄ Li-ion hybrid supercapacitors. The remarkable capability of these materials proves that manipulation of the capacity ratio is a promising technology for high-performance Li-ion hybrid supercapacitors.

• Food Science and Preservation
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• v.19 no.1
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• pp.26-30
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• 2012

The effect of browning inhibitors on quality properties of fresh-cut strawberries was investigated. Half-cut strawberries were treated with dipping solutions alone and with combinations of 1% ascorbic acid, 1% citric acid, 1% sodium chloride, and 1% magnesium chloride, were packaged with low density polyethylene bags, and were kept for 24 hours at $4^{\circ}C$. The levels of oxygen and carbon dioxide in the packages of the samples treated with the combined solutions were the highest and the lowest, respectively. The loss of L value and flesh firmness of fresh-cut strawberries was retarded by the combined solutions than by the dipping solutions alone. The soluble solids and pH were not affected by the browning inhibitor. These results suggest that mixture of ascorbic acid, citric acid, sodium chloride, magnesium chloride may prevent browning and softening of fresh-cut strawberries.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.54-60
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• 2017

In order to identify the characteristics of the flame transfer function gain, cold-flow transfer function was introduced, which is the part of the combustion instability research. Nitrogen and carbon dioxide was used to obtain the cold-flow transfer function and input/output variables was measured by hot wire anemometry. Density and fluid flow rate affect the cold-flow transfer function gain and peak frequency. In addition, acoustic resonance frequency affects the peak frequency of gain in the fuel feeding line.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.6
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• pp.1304-1309
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• 1999

The respiratory characteristics and quality attributes of mature green mume fruits as influenced by modified atmosphere packaging(MAP) conditions during storage at 25oC for 8 days were investigated. The quality attributes of mume fruits were evaluated in terms of fresh weight loss, physiological injury and yellowing. The packaging materials used for MAP were low density polyethylene(LDPE) films with various different thicknesses. Yellowing and fresh weight loss of mume fruits were noticeably reduced by the packaging treatments with LDPE A and B. The physiological injury of the fruits during storage was found to be more severe in LDPE C than others. For LDPE A and B, the oxygen and carbon dioxide contents within the packages of Mume fruits maintained at the levels of 2~3% and 7~8%, respectively. With respect to visual quality, MAP prolonged the shelf life of the fruits much longer compared with the unsealed control. From the experimental results, it is suggested that the LDPE films with the gas trans mission rates of about 2,100 O2 ml/m2.day.atm and 6,700 CO2 ml/m2.day.atm would be proper for MAP of mature green mume fruits during storage at ambient temperature.