• KSBB Journal
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• v.13 no.5
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• pp.483-490
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• 1998

Two unidentified methanotrophic strains (MM-white and MM-red) secreting soluble methane monooxygenase (sMMO) involved in thrichloroethylene biodegradation have been isolated from mixed methanotrophic consortium (MM) around Taejon area. Subsequently four methanotrophic strains were isolated from MM and named according to their color; white (MS-white), yellow (MS-yellow), pink (MS-pink) and reddish brown (MS-rbrown). All strains except MS-yellow which can take glucose as well as methane, metabolized methane as a sole carbon source. They all showed symbiotic behavior when methane was used as the sole carbon source. Optimum conditions of cell growth for MM were pH of 6.8 - 7.2, temperature of 29 - 32$^{\circ}C$, and gas flow rate of 6 (for methane), 40 (for air), and 4 ml/min (for carbon dioxide). The sMMO activity was expressed as naphthalene oxidation rate (${\mu}$mol/ mg protein/ hr). The sMMO activity for MM grown in flask culture with 1 ${\mu}$M of CuSO4 was 36, while it was 61 without copper. The activity for MM grown in the fermentor without CuSO4 was 1077, but is was 197 after reaction with 5 ppm of TCE. The methanotrophs showed significantly high sMMO activity despite the presence of 1 ${\mu}$M of CuSO4, although most of other strains already known could not express sMMO activity under this condition.

• Nuclear Engineering and Technology
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• v.29 no.2
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• pp.110-126
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• 1997

A two-dimensional continuum model for the hydrogen mining phenomena in the containment subcompartment under severe accident conditions has been developed to predict the spatial distribution of the hydrogen concentration. The model can predict the distribution of time-dependent hydrogen concentration for HEDL experiments well. For the simulation of these experiments, the hydrogen is mixed uniform within the test compartment. To predict the extent of non-uniform distribution, the dominant factors such as the geometrical shape of obstacle and velocity of source injection in mixing phenomena are investigated. If the obstacle disturbing the flow of gas mixture exists in the compartment, the uniform distribution of hydrogen might be not guaranteed. The convective circulation of gas flow is separately formed up and down of the obstacle position, which makes a difference of hydrogen concentration between the upper and lower region of the compartment. The recirculation flow must have a considerable mass flow rate relative to velocity of the source injection to sustain the well-mixed conditions of hydrogen. Finally, in order to account for non-uniform distribution of the hydrogen due to the geometrical configuration the maximum-to-average ratio is functionalized.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.88-92
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• 2007

In this paper, the basic experiment, electrolytic cell design and basic manufacturing have been made to interpret the characteristics of Hydrogen-Oxygen-Gas-Generator. As for the detailed matters, the data research on basic technology on Hydrogen-Oxygen-Gas and analysis on characteristics of Hydrogen-Oxygen-Gas from basic experiment. Also the experiment of characteristics and comparative evaluation between constant current source using IGBT converter from existing method and constant current source using new phase shift PWM control method converter. As results when it has injected constant DC current, we has compared Gas quantities by variable ripple frequencies using phase shift PWM control method converter. Therefore, in linear region, it has not different Gas quantities by constant DC current and by phase shift PWM control method converter. Also, it has increased Gas quantities wilder linear region when put ripple frequency at saturation region. Through, Gas quantities and input power, it has acquired higher input power per Gas quantities at put pulse curren. Therefore, when designing converter or inverter for electrolysis, which has ripple current.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.5
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• pp.702-705
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• 2003

Forest by-product silage (FPS) comprised of foliage, shrubs, and wild grasses was prepared to examine feeding value as sole roughage source for spotted (sika) deer. This diet was compared with imported oak leaf hay (OLH) and a commercial mixed ration (CMR) in digestion balance trials with spotted deer. Dry matter intake was highest (p<0.05) on the OLH, whereas intakes of the FPS and CMR were similar (p>0.05). Digestibility of dry matter was highest (p<0.05) for CMR. Digestibility of crude protein was highest in CMR and lowest in OLH and there were significant differences (p<0.05) among diets. Average daily gain, digestible dry matter intake and digestibility of crude fiber did not differ significantly among diets. Nitrogen intake, urinary and digestible nitrogen were highest (p<0.05) in CMR. However, nitrogen retention was not significantly different. Consequently, FPS is a good roughage source for deer having high digestibility, dry matter intake and availability of nitrogen.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.27-35
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• 2012

Recently, there has been increasing interest in the use of rain garden systems as environmentally friendly ecological infrastructures for controlling stormwater runoff and managing non-point source pollution and information for the contamination of soil and plants can be essential for sustainable rain garden management. In this study, four rain garden mesocosms, namely single species planting with Rhododendron lateritium, single species planting with Zoysia japonica, mixed planting with R. lateritium and Z. japonica, and control without plants, were tested to investigate the change in concentrations of nutrients (N and P) and heavy metals (Cd, Cu, Pb, and Ni) in the soil and plants used in the rain garden system. The presence of plants resulted in greater nutrient retention in soil and lower potential leaching from the system. All systems showed an increase in the heavy metal concentrations in soil. The concentrations of most heavy metals were found to be higher in the herbaceous plants (Z. japonica) than in the shrubs (R. lateritium). The belowground part (root) had higher heavy metal concentrations than the aboveground part (leaf) but also showed a potential increase in leaves, and hence, careful plant management should be considered during rain garden operation.

• Microbiology and Biotechnology Letters
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• v.27 no.1
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• pp.46-53
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• 1999

The purpose of this study was to optimize the conditions of continuous mixed culture of C.butyricum and R. spaeroides K-7, which were able to produce hydrogen using biomass-dreived substrate. To investigate the possibility of continuous culture, semi-continuous culture was carried out for 20 days. In semi-continuous culture using the reactor system, the replacement rate of fresh medium was 30% of total medium volume for the highest hydrogen evolution. In continuous culture, the optimum dilution rate was determined to be 0.05$h^{-1}$. The continuous culture produced 3.1 times as compared with the hydrogen on batch culture. On the other hand, the continuous mixed culture produced 1.3~2.1 times as much as hydrogen of the continuous monoculture of C. butyricum. When 10g of glucose in the media (1l) was supplied as a carbon source on continuous culture, mixed culture of C. butyricum and R. sphaeroides K-7 increased hydrogen evolution rate. Because considerable amount of glutamate was contained in waste water of glutamate fermentation, utilization of glutamate was examined in mixed culture. As a result of examination, production of hydorgen was slightly inhibited by high concentration of glutamate, more than 20mM, on continuous monoculture of R. sphaeroides K-7. On the other hand, both on continuous monoculture of C. butyricum and on mixed culture of C. butyricum and R. sphaeroides K-7, production of hydrogen was not inhibited by high concentration of glutamate such as 100mM. Hence this suggests that high concentration of waste water can be used as good substrate for hydrogen production on monoculture of C. butyricum and mixed culture of C. butyricum and R. sphaeroides K-7.

• Animal Bioscience
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• v.36 no.5
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• pp.720-730
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• 2023

Objective: This study investigated the effects of corn silage as a source of microbial inoculant containing antifungal and carboxylesterase-producing bacteria on fermentation, aerobic stability, and nutrient digestibility of fermented total mixed ration (FTMR) with different energy levels. Methods: Corn silage was used as a bacterial source by ensiling for 72 d with an inoculant mixture of Lactobacillus brevis 5M2 and L. buchneri 6M1 at a 1:1 ratio. The corn silage without or with inoculant (CON vs MIX) was mixed with the other ingredients to formulate for low and high energy diets (LOW vs HIGH) for Hanwoo steers. All diets were ensiled into 20 L mini silo (5 kg) for 40 d in quadruplicate. Results: The MIX diets had lower (p<0.05) acid detergent fiber with higher (p<0.05) in vitro digestibilities of dry matter and neutral detergent fiber compared to the CON diets. In terms of fermentation characteristics, the MIX diets had higher (p<0.05) acetate than the CON diets. The MIX diets had extended (p<0.05) lactic acid bacteria growth at 4 to 7 d of aerobic exposure and showed lower (p<0.05) yeast growth at 7 d of aerobic exposure than the CON diets. In terms of rumen fermentation, the MIX diets had higher (p<0.05) total fermentable fraction and total volatile fatty acid, with lower (p<0.05) pH than those of CON diets. The interaction (p = 0.036) between inoculant and diet level was only found in the immediately fermentable fraction, which inoculant was only effective on LOW diets. Conclusion: Application of corn silage with inoculant on FTMR presented an antifungal effect by inhibiting yeast at aerobic exposure and a carboxylesterase effect by improving nutrient digestibility. It also indicated that fermented feedstuffs could be used as microbial source for FTMR. Generally, the interaction between inoculant and diet level had less effect on this FTMR study.

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.61-75
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• 2023

Denitrifying bacteria convert nitrate to nitrogen gas using an external carbon source as an electron donor. The external carbon source affects the denitrification performance and bacterial community structure. Although methanol is a cheap and effective external carbon source, the addition of diverse carbon sources may improve the total nitrogen removal rate and biomass characteristics, such as settleability. In this study, denitrifying reactions were performed using solely methanol and mixed carbon sources of methanol, glucose, and acetate in a sequencing batch reactor. The denitrifying reactor using methanol resulted in a total nitrogen removal rate of 0.39 ± 0.025 kg-N/m³-day while the suspended biomass transformed into dark brown granules. Methyloversatilis discipulorum had the highest predominance at 43.84%. The individual denitrifying biomasses, which were separately enriched with methanol, glucose, and acetate, showed the same total nitrogen removal performance of 0.39 ± 0.016 kg-N/m³-day. However, the addition of mixed carbon sources showed an improved total nitrogen removal rate of 0.42 ± 0.043 kg-N/m³-day, with the domination of Candidatus Saccaribacteria at 25.61%. The denitrifying granules turned pale yellow color. Influent COD/NO₃^--N ratios of 3.5, 5, and 7.5 exhibited COD/NO₃^--N consumptions of 4.3 ± 0.4, 4.4 ± 0.8, and 5.2 ± 0.7, and the consistent predominance of Candidatus Saccharibacteria.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.502-507
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• 2014

In this paper, performance characteristics of cycles were studied when mixed working fluid was used for ocean thermal energy conversion (OTEC). Among the various mixed refrigerants for industrial heat-pump, R32/R152a used in ocean thermal energy conversion system. For simulations, R32/R152a were used in existing closed cycle and Kalina cycle which is used only ammonia and water as mixed refrigerant. Temperature of the warm heat source was 26 and 29 celsius degree, temperature of the cold heat source was 5 celsius degree. In results of simulation, Gross power of the closed cycle on R32 was 22kW, and efficiency of the cycle was 2.02%. When the mixed refrigerant of R32/R152a, in the ratio of 90 to 10, gross power of the closed cycle was 29.93kW, and efficiency of the cycle was 2.78%. Gross power and cycle efficiency of R32/R152a increased by 36% and 37% than those of existing single refrigerant. Additionally, the same simulations were conducted in Kalina cycle with the same various composition ratio of mixed refrigerant.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.770-778
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• 2013

In this study, a liquid carbonation method was applied for producing precipitate calcium carbonate by liquid-liquid reaction. We recycled the recycling water of ready-mixed concrete, one of construction waste for use source of carbonate ion. A supernatant separated from the recycling water of ready-mixed concrete, as a result of ICP analysis of a cation, $Ca^{2+}$ was contained up to 1100 ppm. We used MEA as a $CO_2$ absorbent for the liquid carbonation. A precipitate $CaCO_3$ was produced at more than MEA 20 wt%. The precipitate $CaCO_3$ as a final product was separated and dried. The result of XRD was confirmed the generation of $CaCO_3$ to calcite structure.