• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.13-17
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• 2014

Subcritical water acts like an organic solvent at elevated temperature in terms of its physicochemical properties. Taking into account this advantage, the remediation experiments of benzo[a]pyrene contaminated soil (8.45 mg/kg of initial concentration) were conducted using subcritical water extraction apparatus. The effect of operating factors on the removal efficiency was studied at the varying the conditions of the water temperature ranging $200{\sim}300^{\circ}C$, extraction time 30~90 min, and flow rate 0.3~2.0 mL/min. 12 g of benzo[a]pyrene contaminated soil was inserted into the extraction cell and placed into the reactor and then the subcritical water was driven through the cell. In this study, the removal efficiency of benzo[a]pyrene was increased from 55.1 to 98.1% when the temperature increased from 200 to $300^{\circ}C$. The removal efficiency was decreased from 97.0 to 77.0% when the flow rate increased from 0.3 to 2.0 mL/min, suggesting that the extraction is limited by intra-particle diffusion. The 30 min reaction time was determined as an effective treatment time at $250^{\circ}C$. Based on the results, the optimum condition for the remediation of benzo[a]pyrene contaminated soil was suggested to be $250^{\circ}C$, 30 min, and 0.3 mL/min.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.581-589
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• 1998

Effects of gamma irradiation on hygienic quality, extraction yields and physiological effectiveness in twenty-one kinds of Korean medicinal plants were investigated. Gamma irradiation at $5{\sim}10\;kGy$ eliminated the microorganisms contaminated in Korean medicinal plants. The total extraction yield in fifteen kinds of Korean medicinal plants increased by $5{\sim}25%$ at 10 kGy gamma irradiation. The physiological effectiveness such as antioxidation, anticomplement functions, nitrite scavenging and electron donating abilities of medicinal plants exposed to 10 kGy gamma irradiation were not different from that of the nonirradiated control.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.555-560
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• 2008

Extraction was performed to prepare ash-free coal from low rank coal under the temperature of $200-430^{\circ}C$ and initial pressure of 0.1MPa. Three kinds of coal samples with different rank were used and N-methyl-2-pyrrolidinone(NMP, polar), 1-methyl naphthalene(I-MN, non-polar), Light Cycle Oil(LCO, non-polar) were used as solvents. Results showed that higher extraction yield could be obtained with NMP than with 1-MN and LCO, but the ash concentration shows minimun in the case of 1-MN. Three operation modes were compared, that is, idle, agitation and ultrasonic extraction mode. From the results, it was found that the extraction yield and ash concentration were 70.09% and 1.03% under the agitation mode, 80.7% and 0.76% under the ultrasonic operation mode respectively in the case of NMP used at the temperature of $350^{\circ}C$. Similar results were obtained with 1-MN. Effect of ultrasonic on the extraction was estimated as 15-20% increase in the yields and 26% reduction in the ash concentration.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.392-393
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• 2018

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.721-724
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• 2007

Estimating of LFG emission rate has been well established. But, relatively short history of LFG extraction in Korea, the data and the formular have not been well compared and analyzed. Here, even though the operation period of extraction for Daegu Bangcheon-ri is short, the relevant correlation between estimated and the actual has been tried to find. Hopefully, this will be a guideline for the future LFG forecasting.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.11a
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• pp.201-204
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• 2003

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.588-589
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• 2018

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.153-153
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• 2010

The world is moving towards a post-carbon society and needs clean and renewable energy for sustainable development. There are many methodological approaches which are helping this shift based on analyzed data about energy resources and which focus on limited types of energy including liquid fossil, solid fossil, gaseous fossil, and biomass (e.g. IPCC Guidelines, ISO 14064-1, WRI Protocol, etc.). We should also consider environmental impact (e.g. greenhouse gas emissions, water use, etc.) and the economic cost of the renewable energy to make a better decision. Recently, researchers have addressed the environmental impact of new technologies which include photovoltaics, wind turbines, hydroelectric power, and biofuel. In this work, we analyze the environmental impact with a carbon emission factor to present a correlation between $CO_2$ emission and the cost of energy resources standardized by the energy output. In addition, we reviewed Life Cycle Assessment (LCA) as another methodology. Researchers who are studying energy systems have ignored the impacts of entire energy systems, e.g. the extraction and processing of fossil fuels. In power sector, the assessment should include extraction, processing, and transportation of fuels, building of power plants, production of electricity, and waste disposal. Therefore LCA could be more suitable tool for energy cost and environmental impact estimation.

• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.48-56
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• 2017

Although various methods have been investigated for treatment of crude oil contaminated soil, more researches are still required to preserve soil environment. This study investigated the potential utility of subcritical water in remediation of crude oil contaminated soil under various experimental conditions including temperature ($150-300^{\circ}C$), flow rate (1.0-2.0 mL/min) and extraction time (60-120 min). The removal rate of crude oil gradually increased with increasing temperature and time. After treatment at $200^{\circ}C$ and $300^{\circ}C$ for 60 min, the remaining concentration of crude oil met the Kuwait standard clean-up level (10,000 mg/kg) and the Korean standard level (2,000 mg/kg), respectively. The removal efficiency of crude oil increased from 77.8% to 88.4% with increasing extraction time from 60 to 120 min at $250^{\circ}C$. A decreasing rate of oil removal was observed as flow rate increased, possibly due to channeling flow occurred within the soil body at higher flow rate condition. Overall, the results revealed that subcritical water extraction process could be feasible for remediation of crude oil contaminated soil, and the relative effect of parameters on the oil removal was in the order of temperature > time > flow rate.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.347-357
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• 2018

The applicability of room temperature ionic liquids (RTILs), 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([$C_nmim$] [$Tf_2N$]), was investigated for the extraction of Am(III) and Eu(III) from nitric acid using n-octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) and tri-n-butylphosphate (TBP) as extractants. The distribution ratios of Am(III) and Eu(III) in CMPO-TBP/[$C_nmim$][$Tf_2N$] were measured as a function of various parameters such as the concentrations of nitric acid, CMPO, and TBP. The results were compared with those obtained in CMPO-TBP/n-dodecane (n-DD). With comparable concentrations of the extractants, the distribution ratios obtained with RTILs were much higher than those obtained with n-DD. It was observed that the extraction efficiency was less for Eu(III) than for Am(III). The extraction of Am(III) and Eu(III) decreased with increases in the feed acidity for all three RTILs. The results suggest that the extraction of Am(III) and Eu(III) by CMPO in RTILs from nitric acid proceeds through the cation-exchange mechanism. The distribution ratios of Am(III) and Eu(III) increased with increases in the concentration of CMPO for all three RTILs. A linear regression analysis of the extraction data resulted in a straight line with a slope of about 3, suggesting the involvement of 3 molecules of CMPO during the extraction process.