• KSBB Journal
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• v.17 no.2
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• pp.148-152
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• 2002

The extraction of volatile essential oil using supercritical carbon dioxide with 2%(v/v) ethanol and non-ethanol was performed in a semi-continuous flow extractor at the range of pressures and temperatures 6.9 to 17.2 MPa and 30 to 45$^{\circ}C$, respectively. When ethanol was added to the co-solvent, the solubility of volatile essential oils was increased up to 90% over the neat CO$_2$ value. The most efficiency of extraction of the voilatile essential oils was achieved at 13.8㎫ and 40$^{\circ}C$ by supercritical carbon dioxide with entrainer from Citrus junos peel.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.131-134
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• 2005

Anaerobic reductive dechlorination of tetrachloroethylene(PCE) to ethylene was investigated by performing laboratory experiments using semi-continuous flow two-in-series soil columns. The columns were packed with soils obtained from TCE-contaminated site in Korea. Site ground water containing lactate(as electron donor and/or carbon source) and PCE was pumped into the soil columns. During the first operation with a period of 50 days, injected mass ratio of lactate and PCE was 620:1 and incomplete reductive dechlorination of PCE to cis-DCE was observed in the columns. However, complete dechlorination of PCE to ethylene was observed when the mass ratio increased to 5,050:1 in the second operation, suggesting that the electron donor might be limited during the first operation period. During the degradation of cis-DCE to ethylene, the concentration of hydrogen was $22{\sim}29mM$. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through biological anaerobic reductive dechlorination processes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.43-54
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• 1997

This paper presents an approximate analytical solution to a two-region one-dimensional model for the charging process of stratified thermal storage tanks with variable inlet temperature in the presence of momentum-induced mixing. Based on the superposition principle, an arbitrary-varying inlet temperature is decomposed into inherent discontinuous steps and continuous intervals approximated as a finite number of piecewise linear functions. This approximation allows the temperature of the upper perfectly-mixed layer to be expressed in terms of constant, linear and exponential functions with respect to time. Applying the Laplace transform technique to the model equation for the lower thermocline layer subject to each of three representative interfacial conditions yields compact-form solutions, a linear combination of which constitutes the final temperature profile. A systematic method for deriving solutions to the plug-flow problem having polynomial-type boundary conditions is also established. The effect of adiabatic exit boundary on solution behaviors proves to be negligible under the actual working conditions, which justifies the assumption of semi-infinite domain introduced in the solution procedure. Finally, the approximate solution is validated by comparing it with an exact solution obtained for a specific variation of inlet temperature. Excellent agreements between them suffice to show the necessity and utility of this work.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.68-76
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• 2006

Anaerobic reductive dechlorination of tetrachloroethylene (PCE) to ethylene was investigated by performing laboratory experiments using semi-continuous flow two-in-series soil columns. The columns were packed with soils obtained from TCE-contaminated site in Korea. Site ground water containing lactate (as electron donor and/or carbon source) and PCE was pumped into the soil columns. During the first operation with a period of 50 days, injected mass ratio of lactate and PCE was 620:1 and incomplete reductive dechlorination of PCE to cis-DCE was observed in the columns. However, complete dechlorination of PCE to ethylene was observed when the mass ratio increased to 5,050:1 in the second operation, suggesting that the electron donor might be limited during the first operation period. Dechlorination rate of PCE to cis-DCE was $0.62{\sim}1.94\;{\mu}mol$ PCE/L pore volume/d and $2.76\;{\mu}mol$ cis-DCE/ L pore volume/d for that for cis-DCE to ethylene, resulting that net dechlorination rate in the system was 1.43 umol PCE/L pore volume/d. During the degradation of cis-DCE to ethylene, the concentration of hydrogen in column groundwater was $22{\sim}29\;mM$ and $10{\sim}64\;mM$ for the degradation of PCE to cis-DCE. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through in-situ biological anaerobic reductive dechlorination processes.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.644-650
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• 1999

Trace amount of cobalt in water samples was preconcentrated continuously with an organic precipitant and determined by flame atomic absorption spectrometry. The flow injection technique was used to preconcentrate cobalt by on-line direct precipitation with 1-nitroso-2-naphthol. The precipitation was dissolved with methyl isobutyl ketone (MlBK) and was sent to the flame. The optimum conditions for cobalt determination were determined and used to analyze Co samples. For 1.0 mL of sample, the enrichment factor was 13 and the sample throughput was about lO per hour for 0.5 ppm Co solution. The enrichment factor was increased to 68 fold for 10.0 mL. A semi-reference biologicaI sample was prepared and analyzed. The result was in good agreement with the expected value with RSD of 4%.

• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.182-188
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• 1999

Production of extracellular polysaccharide by Monilinia fructigena in B-I medium containing cereals was higher than that in glucose medium. Productivities in B-I medium and glucose medium were 0.7g/l nd 0.2-03g/l respectively. The maximum content of polysaccharide occurred at the rising point from the lowest pH of culture. As the apparent viscosity of the polysaccharide solution increased, the flow Index (m) decreased, and the consistency Index (Kc) also increased. The polysaccharide solution was a typical pseudoplastic fluid. The mycelium was separated from the culture solution by $300\mu m$ mesh-filter and the polysaccharide was precipitated by adding 50% of ethanol (v/v). The amount of the polysaccharide removed from the filtrated solution was 0.45 g/l and the amount adhered to the mycelium was 0.25g/l. In experiments for investigating growth enhancement of rotifer (Brachionus plicatilis) by the polysaccharide, the dose of the polysaccharide was 1mg per 10,000 organisms of rotifer. Maximum specific growth rate of rotifer with feed consisting of sea Chlorella sp. and the polysaccharide was 1.095/day in the batch culture for 10 days. A semi-continuous culture was done for 30 days, the biomass of rotifer could be harvested twice. Maximum specific growth rate with sea Chlorella sp. and the polysaccharide was 0.734/day before the first harvest, and 1.685/day before the second harvest. Productivity was 38 $cells/ml\; \cdot\; day$ with sea Chlorella sp. and the polysaccharide.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.217-222
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• 1999

A squid viscera oil contains a high content of EPA, DHA, and other valuable polyunsaturated fatty acids. The extractions of squid viscera oil by supercritical carbon dioxide both with/without $3\%$ (v/v) ethanol were performed in a semicontinuous flow extractor at 8.3 to 13.8 MPa and 25 to $50^{\circ}C$. When ethanol was added to $SC-CO_2$, the extraction ratio of lipid increased. The extracts contained high content of unsaturated oils like DHA and EPA. The highest extraction yield of lipid from squid viscera oil extracted by supercritical carbon dioxide was obtained at 12.4 MPa and $40^{\circ}C$ with/without entrainer. The main fatty acids of squid viscera oil extracted by supercritical carbon dioxide were myristric acid (14:0), palmitic acid (16:0), palmitoleic acid (16:1), oleic acid (18:1), arachidic acid (20:0), eicosapentaenoic acid (20:5), and docosahaxaenoic acid (22:6).

• Journal of Animal Environmental Science
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• v.10 no.1
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• pp.1-10
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• 2004

A field-scale(8.6${\times}$2.5${\times}$2.4 m) and pilot-scale(1.39${\times}$0.89${\times}$0.89 m) thermophilic aerobic oxidation (TAO) units were installed to investigate the volume reduction efficiency of slurry, by varying the aeration and treatment temperature of swine manure, and the collected liquid was evaluated as a liquid fertilizer. In the field-scale unit, the aeration level and numbers of foam breakers made different effects on the slurry volume and temperature in the TAO system. The experiments were peformed for three cases, using different levels of aeration and numbers of foam breakers: Treat-A (aeration rate; 120 ㎥ air/hr using 2 air pumps and 2 foam breakers), Treat-B (aeration rate; 180 ㎥ air/hr using 3 air pumps and 3 foam breakers) and Treat-C (aeration rate; 180 ㎥ air/hr using 3 air pumps and 4 foam breakers). With the same input volume (5 ㎥/day) of swine manure slurry, the resulting liquid levels, temperatures and evaporation rates were 50∼100 cm, 31∼$64^{\circ}C$ and 55 $\ell/m^2$/day for Treat-A; 40∼90 cm, 29∼$52^{\circ}C$ and 75 $\ell/m^2$/day for Treat-B; and 40∼70 cm, 45∼$54^{\circ}C$ and 120.0 $\ell/m^2$/day for Treat-C. In the pilot-scale unit, semi-continuous flow of swine manure slurry was introduced. 50 $\ell$ every 2hr(T-1), 50 $\ell$ every 3hr(T-2), 40 $\ell$ every 2hr (T-3) and 60 $\ell$ every 4hr (T-4) within 24 hours, in order to find the maximum slurry volume reduction conditions.