• Journal of Wetlands Research
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• v.13 no.3
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• pp.443-453
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• 2011

This research aims at suggesting the mitigation measures of decreasing pollution by analyzing land cover characteristics according to subwatershed, and non-pollutant load characteristics occurring in each subwatershed. Mushim-cheon is selected as a research area, and HyGIS-SWAT is used as a water quality model. This research analyzed outflow load characteristics by classifying land cover, which has over 50% classified items, into a city area, a farmland area and a forest area. The result shows that the yearly occurrence load quantity represents a farmland area, a forest area and a city area in order. In subwatershed-2, occurrence load quantity is analyzed by setting up a buffer zone in the center of stream, and by changing a farmland area into a natural grass land. Therefore, a farmland area in a subwatershed changes 36.6% into 27.9% and 15.3% comparing to previous land cover change. In the analysis of sediment loads occurrence quantity and nutritive salt load occurrence quantity in subwatershed-2, sediment loads occurrence quantity decreases 52% to about 47%, and nutritive salt load decreases 49% and 34% in compare with previous change. Hereafter, this research will set up the mitigation measures scenario, and find out which is more effective for the mitigation measures.

• Journal of Pharmaceutical Investigation
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• v.35 no.2
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• pp.123-127
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• 2005

An HPLC method was employed for the determination of ethambutol in human plasma. After addition of internal standard (IS, octylamine, $2\;{\mu}g/mL$) and alkalinization of the plasma with 5 M sodium hydroxide, the drug and IS were extracted into the mixture of chloroform and diethyl ether (40:60, v/v). Following a 15-min vortex-mixing and a 10min centrifugation, the organic phase was spiked with $100{\mu}L$ of phenylethylisocyanate $(2000{\mu}g/mL)$ for chemical derivatization, mixed for 5 min and evaporated to dryness under a stream of nitrogen. The residue was reconstituted with $100{\mu}L$ of mobile phase and $20{\mu}L$ was injected into C18 column with a mobile phase consisting of methanol:water (70:30, v/v). The samples were detected utilizing an ultraviolet detector at 200 nm. The method was specific and validated with a limit of $0.15\;{\mu}g/mL$. Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification. The applicability of this method was demonstrated by analysis of human plasma after oral administration of a single 1200-mg dose to 20 healthy subjects. From the plasma ethambutol concentration vs. time curves, the mean AUC was $9.61{\pm}1.64\;{\mu}g{\cdot}hr/mL$ and Cmax of $2.68\;{\mu}g/mL$ reached 2.73 hr after administration. The mean biological half-life of ethambutol was $3.46{\pm}1.21$ hr. Based on the results, this simple and validated assay could readily be used in any pharmacokinetic studies using humans.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.99-106
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• 2015

To estimate the effects of suspended sediments flowing into the Saemangeum Reservoir on the extent of contamination of the reservoir, the suspended sediments were collected with sediment traps, which were installed from the upstream of the Mankyung and Dongjin Rivers to estuary of the reservoir, respectively, and the sedimentation rates and the chemical characteristics of suspended sediments were analyzed. The sedimentation rates in the Mankyung and Dongjin Rivers were ranged from 0.01~5.06 and $0.01{\sim}8.75kg/m^2/day$, respectively. Those were higher to the upstream of rivers, and were mainly affected by flood events. The concentrations of organic matters were from 3.3 to 9.6 times higher than those in the stream sediments and were higher after flood season, indicating the contaminants come from the non-point sources on the basin. The concentrations of total nitrogen and total phosphorus in the suspended sediments showed the same trend with the organic matters. These results indicate that the suspended sediments from the basin of the Mankyung and Dongjin Rivers are highly contaminated and the countermeasures to manage the sources of contamination on the basin are required to maintain the water quality of the Saemangeum Reservoir.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.220-225
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• 2012

This study was carried out to clarify the impact of land use (Castanea crenata, Pinus densiflora and Plantation Land) on soil runoff in small watershed. The soil runoff showed in order of plantation land, Castanea stand and Pinus stand. The resulting models in linear equations of three stands were able to account for 70%, 60% and 60% respectively. The relationship between soil runoff and forest environmental factors was a positive correlation at 1% level with slope, forest type, soil hardness, watershed area, stream length and at 5% level with accumulative rainfall, but was negative correlation at 1% level with coverage. The main factors that affected soil runoff in small watershed showed in order of coverage, accumulative rainfall and stand type. In the stepwise regression between soil runoff and forest environmental factors, the estimation equation is as follow; Y = 31.250 - 1.140(Coverage) + 0.413(Accumulative rainfall) + 20.829(Forest type). The results indicates that dangerous areas of landslide and soil runoff by land use could be applied to the mitigation measures such as afforestation, erosion check dam and revetment for erosion control and water quality management in small watershed.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.412-425
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• 2012

Concrete Soil Erosion Control Dam, which blocks flow of debris flow in torrential stream, are reported to lose expected functions due to structural failure and collapses, caused by poor construction, material deterioration and external impacts. In this paper, an integrity assessment technique for debris barriers was proposed, which allows preliminary detection of problems inherent in debris barriers. The proposed integrity assessment technique is a non-destructive method based on SASW method, one of surface-wave tests. In this paper, a practical procedure and analysis guidelines in applying the SASW technique to debris barrier was proposed and its validity was verified using five decrepit debris barriers older than 20-year old. As a result, the SASW method was validated for the reliable grade evaluation method for concrete soil erosion control dam, and the resulting grades turned out to agree with the results determined by Sabang Associations.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.438-443
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• 2007

This study was done to investigate perchlorate contamination in Nakdong river. The perchlorate was detected in Nakdong river and ranged from ND to $82.1{\mu}g/L$. The highest concentration was observed in Wheguan. The perchlorate concentration was decreased with the down stream of Nakdong river. Three different virgin activated carbons made of each coal(Calgon), coconut(Samchully) and wood(Picabiol) based activated carbon(AC) were tested for an adsorption performance of perchlorate in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of coal, coconut and wood based AC as 2,300 bed volumn(BV), 719 BV and 288 BV respectively. Adsorption capacity(X/M) of real, coconut and wood based AC was observed. The experimental results of adsorption capacity showed that coal based AC was highest$(768.2{\mu}g/g)$, coconut based AC was intermediate$(299{\mu}g/g)$ and wood based AC was lowest$(99.2{\mu}g/g)$. Moreover, carbon usage rates(CURs) for coal, coconut and wood based AC had been shown as 0.71 g/day, 2.16 g/day and 3.45 g/day respectively. The constant characteristic of the system, k of coal, coconut and wood based ACs were found to be 307.2, 102.5 and 94.2, respectively.

• Geophysics and Geophysical Exploration
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• v.6 no.3
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• pp.143-152
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• 2003

Among the various geophysical approaches to identify the leakage of leachate with conductivity variation, conventional electrical resistivity survey has been mainly used at waste landfill. We adopted small-loop electromagnetic (EM) survey using multi-frequencies in parallel with electrical resistivity survey to delineate the leakage of leachate through the shallow soil layer at a waste landfill in Jeju Island, and also with self-potential monitoring to detect the streaming potential produced by the movement of leachate. There were no evidences of leakage from waste landfill according to the results of the electrical resistivity survey and SP monitoring, and it was also true from the results of water quality analysis at stream around waste landfill periodically. On the other hand, the results of one-dimensional inversion of spatially-filtered small-loop EM survey data showed the anomalous zone of low resistivity with depth both around and inner waste landfill.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.419-428
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• 2013

The objectives of this research were to determine ecological characteristics and chemical gradients in two different loach populations-Misgurnus anguillicaudatus ($M_a$) and Koreocobitis rotundicaudata ($K_r$). Eight chemical parameters were compared to test the chemical preferences between the two species. The population of Kr occurred more in better water quality, compared to the $M_a$-population. The $M_a$-population co-occurred more with tolerant species (TS) and omnivores, whereas the $K_r$-population co-occurred more with sensitive species (SS) and insectivores. The differences in the tolerance and trophic composition matched well with the result of stream health assessment, based on the multi-metric model of Index of Biological Integrity (IBI). The IBI value in habitat with the $M_a$-population was "19.6" (range: 8~40) indicating a fair condition, and the IBI values of $K_r$-population was 29.4 (range: 12~40) indicating good condition. Similar results were found in physical habitat health analysis (QHEI). Overall, data analysis showed that the $M_a$-population belong to the tolerant species and $K_r$-population belong to sensitive species in the tolerance classification.

• Journal of Korean Society of Disaster and Security
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• v.12 no.1
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• pp.23-34
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• 2019

It is an urgent issue to manage and reduce non-point pollution sources for improving the water quality of stream and lakes in rural areas. In this study, in order to reduce non-point pollution sources in rural area, Gabion mattresses was proposed to provide protection of riverbanks with anaerobic and aerobic area. The utilization of this was assessed by lab scale model test and pilot plant test. After filling the inside of the gabion mattresses with aggregate, the filtration zone under anaerobic and aerobic conditions was formed to treat the contaminants. In addition, vegetation was deposited on the surfae of the gabion to prevent the inflow of soil and to promote purification by the plant. COD and nitrogen content (T-N, $NH_4{^+}$, -N, $NO_3{^-}N$) were monitored in model and field tests. The lab scale model test showed removal efficiency of 17% of TCOD, 35% of SCOD, 14% of TN, 62% of $NH_4{^+}$, -N, and 33% of $NO_3{^-}$ N. Also, pilot plant test showed removal efficiency of 24% of TCOD, 29% of SCOD, 47% of TN, 50% of $NH_4{^+}-N$, 33% of $NO_3{^-}$, N and 29% of TP.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.320-330
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• 2006

An integrated health of a lotic ecosystem, Cho River, was evaluated by various approaches such as conventional water quality analysis, physical assessments of Qualitative Habitat Evaluation Index (QHEI), and the bioassay of Index of Biological Integrity (IBI) durin August${\sim}$September 2005. The IBI model used in the study was based on original multivariate metric model and then modified the metric attributes of the model for the regional application. Physical habitat health, based on the QHEI, was estimated using eleven metrics. During the study, values of IBI model averaged 36, which was judged as 'fair' to 'good' conditions. Spatial variations in the model values were evident: the headwater site (S1) was estimated as 48, indicating an 'excellent' condition, and the other sites were estimated 32${\sim}$38, 'good' condition. Values of the QHEI in the all sites averaged 148, which is judged as a good condition. The QHEI values varied from 120 (fair condition) to 199 (excellent condition) depending on the location of the stream. Site 5 (S5) was estimated as 'fair${\sim}$good' condition, while Site 7 (S7) was estimated as 'excellent' condition. The biological health, based on the IBI, reflected the habitat health. However, chemical conditions in terms of pH, turbidity, electric conductivity, dissolved oxygen (DO) did not make a difference in the biological health because of minor chemical differences among the locations.