• Journal of Environmental Policy
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• v.14 no.2
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• pp.133-148
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• 2015

The number of used oil refining companies has been increased and it causes shortage of the volume of used oil per recycling company. In addition, the number of used oil collecting companies has been increased and it caused excessive competition among companies with excessive costs. Companies use not only proper used oil but also low quality used oil because of shortage of supply. It is the reason of environmental pollution. Also excessive competition brings high cost of refined oil and it becomes a burden on the consumer. Therefore, the recycling improvement plans of used oil is needed because of these causes. First of all, importing used oil from the developed countries of OECD is the one of solution to secure a used oil supply. However, imported used oil should meet the international quality standards and it is examined twice by international authority institute such as K-petro in both exporting and importing countries. Second, the cost would be reduced with the relaxation on regulations of used oil refinement. However, regulation to sediment and water should be separated. Sediment should be kept within 2% and water should be kept within 5%. It is the way to relax the regulations of used oil refinement with preventing environmental pollutions. Finally, the standard of used oil for heater should be regulated strictly. To prevent pollutions, used oil for heater is limited to high quality waste lubricating oil. Also the air pollution prevention device has to be installed on heater.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.295-303
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• 2000

The water clarification efficiency was examined in a shallow wetland where dense vegetation was formed naturally in an abandoned paddy field. And, also two enclosure experiments were carried out to measure the effects of materials exchange between sediment and the overlying water with the existence of vegetation and accumulated litter. The hydraulic retention time of wetland was regulated in 1.2 day. The removal rates of SS (56%) and $NO_3-N$ (61%) were high, considering its short retention time. However, removal efficiencies of VSS (28%), COD (14%), DOC (1%),and TP (0.2%) were relatively lower. This low removal efficiencies were thought to be due to the release of dissolved form of organic matter and phosphorus from the sediment. Most of constituents except nitrate were higher in the enclosure at the beginning of enclosure installation than that of the outflowing water from wetland. And then, it has fluctuated and decreased with time. The wetland was in equilibrium state of settling, accumulation of organic debris, and regeneration of dissolved material from sediment. So ultimately high primary production by dense vegetation in the wetland may be the reason of unfavorable or low treatment efficiency of wetland after many years of operation for wastewater treatment. However, the water quality of effluent from the wetland showed smaller variation and better condition than that of inflow, especially during storm events. It can be concluded that this wetland is suitable for the improvement of water quality from nonpoint sources.

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.129-132
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• 2008

This study was performed to characterize the seasonal variation of water quality and sediment environment from May, 2007 to February, 2008 in 20 stations of Kamak bay. $4.83\sim11.07mg/L$ on surface and $4.70\sim11.19mg/L$ on bottom in DO, $0.16\sim2.03mg/L$ on surface and $0.10\sim1.55mg/L$ on bottom in COD, $0\sim3.04{\mu}g$-at/L on surface and $0\sim15.21{\mu}g$-at/L on bottom in DIN, $0\sim3.04{\mu}g$-at/L on surface and $0\sim2.01{\mu}g$-at/L on bottom in DIP. IN sediment the ranges were 3.80 to 9.78% in IL, $0\sim5.37mg/g$-dry in AVS and $3.09\sim41.01mg/g$-dry in COD.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2B
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• pp.187-197
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• 2008

This study is to assess the impact of future land use change on hydrology and water quality in Gyungan-cheon watershed ($255.44km^2$) using SWAT (Soil and Water Assessment Tool) model. Using the 5 past Landsat TM (1987, 1991, 1996, 2004) and $ETM^+$ (2001) satellite images, time series of land use map were prepared, and the future land uses (2030, 2060, 2090) were predicted using CA-Markov technique. The 4 years streamflow and water quality data (SS, T-N, T-P) and DEM (Digital Elevation Model), stream network, and soil information (1:25,000) were prepared. The model was calibrated for 2 years (1999 and 2000), and verified for 2 years (2001 and 2002) with averaged Nash and Sutcliffe model efficiency of 0.59 for streamflow and determination coefficient of 0.88, 0.72, 0.68 for Sediment, T-N (Total Nitrogen), T-P (Total Phosphorous) respectively. The 2030, 2060 and 2090 future prediction based on 2004 values showed that the total runoff increased 1.4%, 2.0% and 2.7% for 0.6, 0.8 and 1.1 increase of watershed averaged CN value. For the future Sediment, T-N and T-P based on 2004 values, 51.4%, 5.0% and 11.7% increase in 2030, 70.5%, 8.5% and 16.7% increase in 2060, and 74.9%, 10.9% and 19.9% increase in 2090.

• Journal of environmental and Sanitary engineering
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• v.10 no.3
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• pp.56-66
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• 1995

To investigate environmental impacts of inland fish- farms on the water quality of a stream, environmental parameters including physical, chemical and biological factorswere estimated at trount- farm in 1994. Influences( F-1) were polluted as passing through fish tank( F-2) and settle pond( F-3), so organic and inorganic nutrient concentrations became very high in effluents( F-4). BOD$_{5}$, Chl. a, Nitrite and heterotrophic bacterial numbers in the junction site(5-2) of F-4 and S-1( upstream) were highest among the stream sites. BOD$_{5}$ was proved to a good parameter of organic pollution, and nitrite of Inorganic nutrients in the fishery and it's affected stream, The high concentration of BOD$_{5}$ and Chl. a in S-2 were decreased in downstream(5-3, 5-4). It seems that this results are due to dilution or sedimentation effect. This supposition requires further testing about the sediment of stream. The results of this paper demonstrate that fish farming can deteriorate water quality of a stream by changing environmental factors.

• Environmental Analysis Health and Toxicology
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• v.16 no.4
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• pp.153-159
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• 2001

The main point source of pollution of the Keumho river in Taegu, Korea, stems from waste from the areas of industrial complexes . Although it is widely accepted that pollutants in waste water negatively effects general water quality, it is difficult to evaluate the effluent effect because of varying conditions in ambient water and inconclusive knowledge of causative pollutants. To analyze the water in relation to the industrial effluent in the area, pH. temperature, conductivity, and Microtox toxicity of various river samples were measured. Water samples were collected every 2 hours for 36 hours from Keumho river and Dalseo stream. Data from continuous monitoring for 36 hours showed that effluent in Keumho river originated from Dalseo stream, which is near adjacent to industrial complexes. Change in toxicity and other factors tested during the 36 hours indicated that continuous monitoring was necessary for a satisfactory effluent toxicity test Furthermore, in addition to water quality monitoring, it was concluded that sediment toxicity also needed to evaluate effluent effects.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.579-582
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• 2003

Water quality model applicable paddy field was developed using field experiment during $1999{\sim}2002$. This model involves inputs from fertilization and sediment release as dirac delta function and continuous source function, respectively, and can simulate various processes such as ponded depth, surface drainage, total nitrogen concentration and total phosphorus concentration in a daily basis. Water quality model for paddy field developed in this study is simply, needs little parameters, but appeared high applicability to evaluate paddy filed drainage.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.479-482
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• 2003

Landsat-TM images were applied for evaluating the spatial variations of flow and water quality at the Saemankeum areas. For supervised classifications, the results from hydrodynamic modeling and water quality data were compared to the reflectance characteristics of the satellite images. Multiple regression analyses indicated that suspended sediment, transparency, salinity, total nitrogen, and total phosphorus showed a good relationship to the signature. Supervised classifications showed spatial variations of the water environments at the areas under construction. The results showed the satellite imagery may be applied for the project areas with a reasonable degree of accuracy.

• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.201-205
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• 2000

Eleven runoff $plots(3{\times}15\;m)$ were built on a sloping field of a high plateau in Kangwon Province, Korea. The plots were treated with different tillage, residue covers and fertilizers, corn and potato were cultivated, and sediment discharge was measured from the plots for 3 years. Agricultural management practices were monitored around the plots to develop adequate best management practices. The least sediment occurred from the plots with no-till and 100% residue cover $(corn,\;0.1{\sim}2.2\;t/ha/year)$ and with contour tillage and vinyl sheet cover plots $(potato,\;0.1{\sim}0.2\;t/ha/year)$. The largest sediment was measured from the plots with up-and-down till and no cover ($11{\sim}33$ and $16{\sim}31\;t/ha/year$ from corn and potato plots, respectively). The type of organic and commercial fertilizers seemed not to affect sediment discharge. Sediment discharge from contour plots were largely dependent on the collapse of ridges due to the flush of water stored in furrows. The sediment discharge from contour corn and potato plots with no residue cover was $10{\sim}27$ and $16{\sim}24\;t/ha/year$, respectively. No-till with residue cover, vinyl cover for tuber crops, construction of furrow dam, frost heave research, furrow and ridge tillage with furrow dam after tuber crop harvest, limited stalk harvest of row crops, use of winter cover crops, and other common best management practices were recommended to minimize the sediment discharge from a high plateau sloping land culture.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.656-664
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• 2010

We investigated the levels and distribution patterns of 16 priority polycyclic aromatic hydrocarbons (PAHs), 12 Coplanar polychlorinated biphenyls (Co-PCBs) and organochlorine pesticides (OCPs) in the surface sediments from the Nakdong river basin, Korea. The levels of 16 PAHs and 12 Co-PCBs in the river sediment samples ranged from not detected (N.D.)~969.3 ng/g-dry, 4.2~7716.5 pg/g-dry (0.0~10.1 pg-TEQ/g-dry), respectively. Also, the levels of 16 PAHs were from 5.8~2987.2 ng/g-dry and 4.3~461.1 pg/g-dry (0.0~0.6 pg-TEQ/g-dry) for 12 Co-PCBs in the lake sediment samples. Only dichloro-diphenyl-trichloroethane (DDT) were detected among target OCPs and the concentration ranged from N.D.~1.5 ng/g-dry in the river sediment samples. These contamination levels were far below the guideline values suggested for environmental quality assessment. Low molecular weight PAHs were dominant in the river sediment samples, while middle and high molecular weight PAHs were dominant among 16 PAHs in the lake sediment samples. PCB-118 and PCB-105 were predominant congeners in the sediment, which were similar to the results obtained from previous studies. With these results, the assessment of potential sources of PAHs and Co-PCBs contamination in the sediments of the Nakdong river basin was performed. The pyrogenic-PAHs originated from combustion of fossil fuel and biomass were related with the PAHs contribution in most of the sediment samples, and Co-PCBs in the sediment samples were related with commercial PCB products.