• Journal of Environmental Science International
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• v.19 no.2
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• pp.247-254
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• 2010

Ultrasound and Surfactant aided soil washing process has been shown to be an effective method to remove diesel from soils. The use of surfactants can improve the mobility of diesel in soil-water systems by increasing solubility of adsorbed diesel into surfactant micelles. However, a large amount of surfactant is required for treatment. In addition, synthetic surfactants, specially anionic, are more toxic and the surfactant wastewater is hard to treat by conventional wastewater treatments even by AOPs. Ultrasound improves desorption of the diesel adsorbed on to soil. The mechanisms are based on physical breakage of bonds by hot spot, directly impact onto soil particle surface, the fragmentation of long-chain hydrocarbons by micro-jet and microstreaming in the soil pores. The use of ultrasound as an enhancement method in both anionic and nonionic surfactant aided soil-washing processes were studied. And all experiments were examined proceeded under CMC surfactant concentration, frequency 35 khz, power 400 W, Soil-water ratio 1:3(wt%), particle size 0.24 ~ 2mm and initial diesel concentration. 20,000 mg/kg. Combination with ultrasound showed significant enhancements on all the processes. Especially, nonionic surfactant Triton-X100 with ultrasound showed remarkable enhancements and diesel removal rate enhanced by ultrasound helps desorpting of surfactant adsorbed onto soils which prevented decreasing surfactant activity.

• Journal of Soil and Groundwater Environment
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• v.16 no.5
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• pp.31-41
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• 2011

The objectives of this study were to investigate the efficiencies of the stabilizers such as mono-potassium phosphate (MKP), phosphate fertilizer and red mud in treating the mine tailings contaminated with heavy metals and to characterize the changes in fractionations of the heavy metals during the stabilization. The TCLP results showed that the stabilization efficiencies of Cd, Pb and Zn increased with the increase in the stabilizer dosage and the reaction times. MKP showed the highest efficiencies for the heavy metals stabilization among the stabilizers tested. When the mine tailings were amended with MKP, the TCLP concentrations of Cd, Pb and Zn were reduced by 79~97%, 61~84%, and 89~99%, respectively. When the composite stabilizers, MKP/phosphate fertilizer or MKP/red mud, were used, the stabilization efficiencies were lower than when MKP was used as a single stabilizer. The sequential extraction results showed that carbonates fraction of Cd and Zn increased generally. Especially, when red mud was used, carbonates fraction of Cd and Zn increased 5 and 18 times, respectively. In the case of Pb, the treatment with MKP increased residual fraction by 10 times. The results showed that MKP was the most effective in stabilizing the heavy metals (Cd, Pb and Zn) to improve the efficacy of the composite binders.

• The Korean Journal of Emergency Medical Services
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• v.8 no.1
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• pp.179-187
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• 2004

The purpose of the study was to injury types in Daegu subway fire accident, Sampung department store collapse, Mokpo airport civil aircraft accident, and Buan sunken ship disaster. The conclusion obtained from these analyses are as following. 1. The total of victims were Sampung department store collapse(l440 people). Buan sunken ship disaster(355 people), Daegu subway fire accident(340 people), and Mokpo airport civil aircraft accident(110 people). 2. The total of dead people were Sampung department store collapse(502 people), Buan sunken ship disaster(287 people), Daegu subway fire accident(192 people), and Mokpa airport civil aircraft accident(66 people). 3. The total of injured people were Sampung department store collapse(938 people), Daegu subway fire accident(148 people), Mokpo airport civil aircraft accident(84 people), and Buan sunken ship disaster(67 people). 4. The major types of victims presented smoke inhalation such as coughing, dyspnea, and sore throat in Daegu subway fire accident. 5. The major types of victims presented crushing(multiple fractures), vertebral, and soft tissues injuries in Sampung department store collapse. 6. The major types of victims presented multiple fractures. In addition to, a lot of people showed vertebral injuries and shock symptoms in Mokpo airport civil aircraft accident. 7. The major types of victims presented drowning as well lots of hypothermia patients in Buan sunken ship disaster. There were a wide variety of types in human disaster. Therefore, the most important disaster training program need to each disaster aspect in the local emergency medical services system. Moreover, the emergency medical services personnel should be understand and training for injury types of each human disaster.

• Journal of Environmental Science International
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• v.22 no.5
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• pp.599-608
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• 2013

Jeju island, which is located along the moving path of typhoon, suffers from flooding and overflow by torrential rain. So abrupt runoff occurring, damages of downstream farm field and shore culturing farms are increasing. In this study, Oaedo stream, one of the mountainous streams on Jeju island, was selected as the basin of study subject and was classified into 3 sub-basins, and after the characteristics of subject basin, the soil erosion amount and the sediment delivery of the stream by land usage distribution were estimated with the use of SATEEC ArcView GIS, the sediment yield amount of 2000 and 2005 was analyzed comparatively. As a result of estimating the sediment yield amount of 2000, the three sub-basins were respectively 12,572.7, 14,080 and 157,761 tons/year. and sediment yield amounts were estimated as 35,172.9, 5,266 and 258,535 tons/year respectively in 2005. The soil erosion and sediment yield amount of 2005 using single storm rainfall were estimated high compared with 2000, but for sub-basin 2, the values rather decreased due to changes in land use, and the land coverage of 2005, since there are many classifications of land usage compared with 2000, enabling to reflect more accurate land usage condition, could deduce appropriate results. It is anticipated that such study results can be utilized as basic data to propose a direction to predict the amount of sediment yield that causes secondary flooding damage and deteriorates water quality within detention pond and grit chamber, and take action against damages in the downstream farm field and shore culturing farms.

• Journal of Environmental Science International
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• v.26 no.12
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• pp.1321-1331
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• 2017

This study reviewed the applicability of the existing flood discharge calculation method on Jeju Island Han Stream and compared this method with observation results by improving the mediating variables for the Han Stream. The results were as follows. First, when the rain-discharge status of the Han Stream was analyzed using the flood discharge calculation method of the existing design (2012), the result was smaller than the observed flood discharge and the flood hydrograph differed. The result of the flood discharge calculation corrected for the curve number based on the terrain gradient showed an improvement of 1.47 - 6.47% from the existing flood discharge, and flood discharge was improved by 4.39 - 16.67% after applying the new reached time. In addition, the sub-basin was set separately to calculate the flood discharge, which yielded an improvement of 9.92 - 32.96% from the existing method. In particular, the steepness and rainfall-discharge characteristics of Han Stream were considered in the reaching time, and the sub-basin was separated to calculate the flood discharge, which resulted in an error rate of -8.77 to 8.71%, showing a large improvement of 7.31 - 28.79% from the existing method. The flood hydrograph also showed a similar tendency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.277-283
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• 2016

Recently, the interests in three-dimensional design and BIM(Building Information Modeling) are increasing in civil engineering sector and the researches about three-dimensional design and quantity take-off methods for civil engineering structures have been conducted. However, these studies are just carried out the 3D design and quantity calculation of civil structures on the road or railway such as bridges and tunnels. The study on the quantity take-off methods and the evaluation of calculated results on the earth works should be performed in more detail. Based on these backgrounds in mind, the study was conducted the three-dimensional road design and evaluated the quantity take-off results on the earth works using 3D calculation method(average end area method, prismoidal method and composit method). The calculated quantity from composit method showed about 5% error of measuring efficiency than the average end area method, and when reporting the quantity calculation of earth works, it is necessary to specify the calculation method using quantity take-off of earth works.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.417-426
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• 2016

SWAT model usually underestimates daily peak discharges. To resolve this problem, in this study, the algorithm related with the surface flow simulation was modified by partitioning excessive infiltration based on the relative length between overland flow time of concentration and percolation travel time in soil water zone and by computing time of concentration varying with the amount of surface flow. The modified SWAT was applied to the Chungju dam watershed to assess the increasing effects of daily peak discharges. The daily peaks simulated by the modified SWAT were on average 10% higher than those by original SWAT for the peaks above $5,000m^3/s$. The modified SWAT was found to be able to more accurately reproduce daily peaks, particularly showing increase rates of 9.9%, 18.6% and 12.6%, respectively, for top three peaks that occurred in the years of 1990, 2002, and 2006.

• Environmental Engineering Research
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• v.15 no.4
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• pp.207-213
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• 2010

This study investigated the potential of using bottom ash to be used as an adsorbent for the removal of lead (Pb) from aqueous solutions. The physical and chemical characteristics of bottom ash were determined, with a series of leaching and adsorption experiments performed to evaluate the suitability of bottom ash as an adsorbent material. Trace elements were present, such as silicon and aluminum, indicating that the material had a good adsorption capacity. All heavy metals leached during the Korea standard leaching test (KSLT) passed the regulatory limits for safe disposal, while batch adsorption experiments showed that bottom ash was capable of adsorbing Pb (experimental $q_e$ = 0.05 mg/g), wherein the adsorption rate increased with decreasing particle size. The adsorption data were then fitted to kinetic models, including Lagergren first-order and Pseudo-second order, as well as the Elovich equation, and isotherm models, including the Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The results showed that pseudo-second order kinetics was the most suitable model for describing the kinetic adsorption, while the Freundlich isotherm best represented the equilibrium sorption onto bottom ash. The maximum sorption capacity and energy of adsorption of bottom ash were 0.315 mg/g and 7.01 KJ/mol, respectively.

• Environmental Engineering Research
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• v.15 no.4
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• pp.197-205
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• 2010

Recent years have witnessed increasing interest in wetland constructions in Korea as a flood control measure during the flood season and for consideration of the ecology during the non-flood season. In this study, hydraulic and hydrologic analyses were performed on a wetland construction plan for use as an alternative sustainable flood defense during the flood season, as well as a wetland that can protect the ecosystem during the non-flood season. The study area was the basin of the Topyeong-cheon stream, which is a tributary of the Nakdong River, including the Upo wetland, which is registered in the Ramsar Convention and the largest inland wetland in Korea. Wetlands were to be constructed at upstream and downstream of the Upo wetland by considering and analyzing seven scenarios for their constructions to investigate the effect of flood control during the flood season; it was found the best scenario reduced the flood level by 0.56 m. To evaluate the usefulness of the constructed wetlands during the non flood season, the water balance in the wetlands was analyzed, with the best scenario found to maintain a minimum water level of 1.3 m throughout the year. Therefore, the constructed wetlands could provide an alternative measure for flood prevention as well as an ecosystem for biodiversity.

• Asian Journal of Atmospheric Environment
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• v.11 no.1
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• pp.37-53
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• 2017

The effectiveness of four air fresher (AF) systems was evaluated with respect to their removal efficiencies against offensive odorants. For this purpose, malodorous species were generated by exposing freshly cooked foods emitting odorants with levels moderately above their respective threshold values in a confined room. The deodorization efficiency of the four AF systems was then tested for a period of 30 min by estimating the extent of reduction in odorant levels after the operation of each AF. The removal efficiency of the four AF units against each odorant was evaluated as follows: (1) between AF products from different manufacturers, (2) between odorants and ultrafine particulate matter ($PM_{2.5}$), and (3) between operation and natural degassing. The average sorptive removal of odorants was generally <80% and considered less effective or non-effective relative to $PM_{2.5}$. Further examination of odor reduction, if evaluated in terms of odor indices like odor intensity (OI) and odor activity value (OAV), recorded a mean of 33% and 87%, respectively. The overall results of this study confirmed that all tested AF units were not effective to resolve odor problems created under our testing conditions.