• Journal of Wetlands Research
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• v.14 no.1
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• pp.59-73
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• 2012

The importance of rice paddy wetland has been raised since the 10th Ramsar Convention in 2010. However, there is shortage of study on the evaluation of rice paddy wetland and also of the study on the effect of organic agriculture on the vegetation characteristics. Accordingly, this study examined the vegetation characteristics of organic rice paddy for the basic resources of evaluating value of rice paddy wetland. 6 places of organic rice paddy and conventional rice paddy were chosen as research targets. It analyzed the function of 'Floral Diversity and Wildlife Habitat' among the revised RAM, an existing wetland evaluation system. As to the factor affecting the analysis result, simple land-use result was proved to determine the evaluation. As a result of vegetation investigation total 176 taxa, 53 families, 146 generics, 148 species, 26 varieties and 1 forma. When the difference of appearance of life form between organic area and conventional area was examined, organic paddy had higher appearance of life form in Therophyte and Megaphanerophyte. For the distribution of Naturalized plants, organic rice paddy had lower naturalized rate and urbanization index than conventional rice paddy. As to the Pearson correlation analysis between growing condition and vegetation characteristics, variety of rice paddy vegetation showed it was not heavily influenced by the land use. However, the organic rice paddy area had more variety in vegetation than conventional rice paddy. There was about 1% correlation with types of Cyperaceae, which means that the classification group of Cyperaceae can be utilized in evaluating rice paddy wetland later on. It is determined that the wetland evaluation has been widely influenced by soil environment, water environment and surrounding natural and artificial landscape as well as vegetation characteristics. Accordingly, further research seems to be required with minute investigation to an extensive area.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.59-77
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• 2015

In order to meet the new requirements for landfill materials, this study planned a study to apply mixed soil of mixing bottom ash and coastal dredged soil to the dredged ground. Coal ash generated from thermal power plant is divided into fly ash and bottom ash. In the case of fly ash, many studies have been conducted because small particles causes permeability coefficient to be small during recycling so no problem has been raised in the environmental area but the utilization of bottom ash has been limited because environmental problems have been raised during recycling due to its larger particle size and greater permeability coefficient. According to recently published studies, however, the results of the study that conducted the water analysis of leachate generated in the ground improvement section using bottom ash showed that heavy metal contamination levels were found to be within the reference value and no significant environmental problems were found so utilization of bottom ash is evaluated to increase significantly in the future. This bottom ash has the particle size of sand and only transportation costs need to be considered when providing materials because the majority has been disposed and it is judged as the most suitable material in dredging landfill in the economic aspect because most thermal power plants are located in the coast and transportation costs can be reduced by ship. Also, research on mixed soil that can maximize the effect of the construction period and construction cost savings than dredged soil is determined as needed because the demand for coastal dredging reclamation is increasing such as Saemangeum project etc. Therefore, we studied self-weight consolidation characteristics depending on sample processing and mixing method of mixed soil by carrying out interior self-weight consolidation experiments on mixed soil of mixing bottom ash and Kaolinite according to the new development needs of recent coastal reclaimed ground and these result findings are expected to be used as basic data when applying the large coastal dredged ground in the future.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.239-256
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• 2003

The purpose of this study is to investigate the hydrochemical characteristics of emergency-use groundwater in the Daejeon area, and to elucidate the contamination source of $NO_3-N$ and the origin of sulfate in the groundwater. The groundwater shows weak acidic pH, the electrical conductivity ranging from 142 to $903{\;}\mu\textrm{S}/cm$, and the hydrochemical types of $Ca-HCo_3$ and $Ca-Cl(SO_4,{\;}NO_3)$. The Box-Whisker analysis and the Krigging analysis of chemical data of groundwater were made to demonstrate the concentration distribution of hydrochemical composition, and to compare the trend of hydrochemical data. The groundwater in the area of Dong-gu, Jung-gu and Daeduk-gu, where are old town, shows higher electrical conductivity, nitrate content, sulfate and $EpCO_2$ levels than groundwater in new town area of Seo-gu and Yusung-gu. ${\delta}^{15}N$ of groundwater in the area of Seo-gu and Yusung-gu ranges from +7.4 to $+9.6{\textperthousand}$, indicating that major contamination source of $NO_3-N$ is the leakage from municipal sewage pipe lines. ${\delta}^{15}N$ of groundwater in the old town area of Tong-gu, Jung-gu and Daeduk-gu shows the range between +10.2 and $+23.5{\textperthousand}$, meaning that major contamination source is leakage of septic tank. ${\delta}^{34}S$ of groundwater shows the range of $+3~13.4{\;}{\textperthousand}$. Sulfur isotope indicates the possibility of a sulfate reduction and the input of anthrophogenic source.

• Journal of Korean Society of Forest Science
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• v.90 no.2
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• pp.197-209
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• 2001

TOPMODEL, semi-distributed hydrological model, is frequently applied to predict the amount of discharge, main flow pathways and water quality in a forested catchment, especially in a spatial dimension. TOPMODEL is a kind of conceptual model, not physical one. The main concept of TOPMODEL is constituted by the topographic index and soil transmissivity. Two components can be used for predicting the surface and subsurface contributing area. This study is conducted for the validation of applicability of TOPMODEL at small forested catchments in Korea. The experimental area is located at Gwangneung forest operated by Korea Forest Research Institute, Gyeonggi-do near Seoul metropolitan. Two study catchments in this area have been working since 1979 ; one is the natural mature deciduous forest(22.0 ha) about 80 years old and the other is the planted young coniferous forest(13.6 ha) about 22 years old. The data collected during the two events in July 1995 and June 2000 at the mature deciduous forest and the three events in July 1995 and 1999, August 2000 at the young coniferous forest were used as the observed data set, respectively. The topographic index was calculated using $10m{\times}10m$ resolution raster digital elevation map(DEM). The distribution of the topographic index ranged from 2.6 to 11.1 at the deciduous and 2.7 to 16.0 at the coniferous catchment. The result of the optimization using the forecasting efficiency as the objective function showed that the model parameter, m and the mean catchment value of surface saturated transmissivity, $lnT_0$ had a high sensitivity. The values of the optimized parameters for m and InT_0 were 0.034 and 0.038; 8.672 and 9.475 at the deciduous and 0.031, 0.032 and 0.033; 5.969, 7.129 and 7.575 at the coniferous catchment, respectively. The forecasting efficiencies resulted from the simulation using the optimized parameter were comparatively high ; 0.958 and 0.909 at the deciduous and 0.825, 0.922 and 0.961 at the coniferous catchment. The observed and simulated hyeto-hydrograph shoed that the time of lag to peak coincided well. Though the total runoff and peakflow of some events showed a discrepancy between the observed and simulated output, TOPMODEL could overall predict a hydrologic output at the estimation error less than 10 %. Therefore, TOPMODEL is useful tool for the prediction of runoff at an ungaged forested catchment in Korea.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.285-293
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• 2007

The study was to determine zonal characteristics of nutrients and chlorophyll and evaluate their trophic relations in Daechung Reservoir. For this study, we compared longterm water quality data among three zones along with trophic state using 1993 to 2002 dataset, obtained from the Ministry of Environment, Korea. Total phosphorous (TP), Secchi depth (SD) and chlorophyll (CHL) showed typical longitudinal declines from the riverine to lacustrine zone, but total nitrogen (TN) was not evident. Largest seasonal variations in TP and CHL occurred during the summer monsoon from July to August. In the reservoir, ambient TN averaged 1.67 mg $L^{-1}$ and ratios of TN : TP averaged 88.04, indicating that nitrogen is not likely limited but phosphorus limitation was evident. Trophic State Index (TSI), based on CHL, TP, and SD, varied depending on the zones and seasons. Mean TSI (TP) in the riverine zone was 62 during the monsoon, indicating a hypertrophic condition, whereas the mean was 40 in the lacustrine, indicating a nearly oligotrophic. Values of TSI (CHL) showed maximum in the transition zone during the monsoon. The deviation analysis of TSI showed that about 65% of TSI (CHL)-TSI (TP) and TSI (CHL)-TSI (SD) values were less than zero and the lowest values were -42, indicating an effect of inorganic turbidity on algal growth in the reservoir. Correlation analysis of CHL vs. SD shewed greater correlation coefficient (p<0.001, r=-0.47) in the transition than other two zones (p<0.001, $r{\leq}-0.40$). Correlation analysis of TP vs. CHL was greatest in the lacustrine and TP was minimum in the lacustrine zone, indicating a lowest yield of algal biomass in the lacustrine. Overall data suggests that zonal response of chlorophyll yield at a given nutrient unit is clearly differed among the longitudinal gradients, so the management strategy such as cross sectional modelling should be provided in each zone.

• Journal of Soil and Groundwater Environment
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• v.12 no.2
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• pp.9-19
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• 2007

This study investigated the interaction between groundwater and stream water systems, which is caused by the artificial weir on streambed, enforcing external stresses on the groundwater system. The study area is in Nami Natural Recreation Woods located in Chungcheongnam-do Geumsan-gun Nami-myeon Geoncheon-ri. In this study both of hydrophysical methods (hydraulic head) and hyrdochemical investigations (pH, EC, major ion analysis) were applied. In order to identify the relationship between each of study results, cross-correlation analysis is performed. From results of hydrophysical methods, water level fluctuation at BH-14, installed by the weir, shows the double-recession pattern much more frequently and much higher amplitudes than the fluctuation at each of other monitoring wells. Using the results by hydrochemical investigations, hydrochemical properties at BH-14 is similar to the hydrochemical characteristics in stream water. To analyze the interrelationships between the results from each of applied methods, cross-correlation analysis was applied. Results from the correlation analyses, water levels at BH-14 and stream weir showed the highest cross-correlation in hydrophysical aspects. On the other hand, the correlation between stream weir and bridge was the highest in hydrochemical aspects. The difference between the results from each of methods is due that the hydrophysical response at BH-14, such as water level, is induced by the pressure propagation-not with mass transfer, but the hydrochemical interaction, caused by mass transport, takes much more times. In conclusion impermeable artificial weir on streambed changes the interfacial condition between the stream and surrounding aquifers. The induced water flux into the groundwater system during flood period make water level at BH-14 increase instantly and groundwater quality higly similar to the quality of stream water. Referred similarities in both of water level and water quality at BH-14 become much higher when water level at weir grow higher.

• Economic and Environmental Geology
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• v.44 no.2
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• pp.135-152
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• 2011

Nitrate concentrations in springs at the southern slope of Jeju Island were predicted using multiple linear regression (MLR) of spatial variables including hydrogeological parameters and land use characteristics. Springs showed wide range of nitrate concentrations from <0.02 to 86 mg/L with a mean of 20 mg/L. Spatial variables were generated for the circular buffer when the optimal buffer radius was assigned as 400 m. Selected regression models were tested using the p values and Durbin-Watson statistics. Explanatory variables were selected using the adjusted $R^2$, Cp (total squared error) and AIC (Akaike's Information Criterion), and significance. In addition, mutual linear relations between variables were also considered. Small portion of springs, usually <10% of total samples, were identified as outliers indicating limitations of MLR using circular buffers. Adjusted $R^2$ of the proposed models was improved from 0.75 to 0.87 when outliers were eliminated. In particular, the areal proportion of natural area had the greatest influence on the nitrate concentrations in springs. Among anthropogenic land uses, the influence of nitrate contamination is diminishing in the following order of orchard, residential area, and dry farmland. It is apparent quality of springs in the study area is likely to be controlled by land uses instead of hydrogeological parameters. Most of all, it is worth highlighting that the contamination susceptibility of springs is highly sensitive to nearby land uses, in particular, orchard.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.480-491
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• 2015

In this study, methods using LDC (Load Duration Curve) and watershed model were suggested to develope management targets and evaluate target achievement for non-point source pollution management considering watershed and runoff characteristics and possibility for achievement of target. These methods were applied for Saemangeum watershed which was designated as nonpoint source pollution management area recently. Flow duration interval of 5 to 40% was selected as flow range for management considering runoff characteristics and TP was selected as indicator for management. Management targets were developed based on scenarios for non-point source pollutant reduction of management priority areas using LDC method and HSPF model which was calibrated using 4 years data (2009~2012). In the scenario of LID, road sweeping and 50% reduction in CSOs and untreated sewage at Jeonju A20 and 30% reduction in fertilizer and 50% in livestock NPS at Mankyung C03, Dongjin A14 and KobuA14, management targets for Mangyung bridge, Dongjin bridge, Jeonju stream and Gunpo bridge were developed as TP 0.38, 0.18, 0.64 and 0.16 mg/L respectively. When TP loads at the target stations were assumed to have been reduced by a certain percentage (10%), management targets for those target stations were developed as TP 0.35, 0.17, 0.60 and 0.15 mg/L respectively. The result of this study is expected to be used as reference material for management master plan, implementation plan and implementation assessment for non-point source management area.

• Journal of Food Hygiene and Safety
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• v.22 no.4
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• pp.338-345
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• 2007

This study surveyed on the actual conditions of using sanitizers and disinfectants for improvements of sanitization on food utensils at 105 school and 20 industry foodservice operations. The questionnaire which was administered to 125 foodservices was used as a mail or visitation method. The answers of asking "Perception on temporary authorization system of sanitizers and disinfectants on food utensils" were 75% in contract managed school foodservices, 81.8% in self operated school foodservices, and 50% in industry. Main factors to choose sanitizers were sterilizing power (38.6%, 28.6%, 38.9%) and safety (32.6%, 46.1%, 33.3%) at every foodservices. Keeping ratio of sanitizers and disinfectants guidelines in contract managed school, self operated school and industry foodservices were 64.8%, 52% and 73.7%, respectively. If easy and practical guideline is developed, most foodservices replied to use if for disinfection of foodservices. Most of the foodservices were not only knowing sanitizers and disinfectants but also possessing a guideline. However, they didn't perform disinfection according to the guideline due to its complexity. Consequently, we suggest that it is necessary to provide an easy and practical "sanitizers and disinfectants guideline" and useful information.

• Current Research on Agriculture and Life Sciences
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• v.6
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• pp.99-104
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• 1988

Water polution status of urban streams in Daegu city were observed to provide the basic information for the effective purification of urban sewage and the conservation of Keumho river. Periodically, pH, DO, COD, nitrate and phosphate of water were investigated at Yee cheon, B$\ddot{o}$m$\ddot{o}$ cheon, Chilsung cheon, Dalseo cheon and Kongdan cheon. The results were as follows. 1) The ranges of average values of analyzed components for 12 months at six sampling sites were pH 7.3-8.2, DO trace-6.5ppm, COD 20.4-116.9ppm, T-N 23.2-31.7ppm, $NH_4$-N 18.3-27.7ppm, $NO_2$-N 0.08-1.89ppm, $NO_3$-N 0.19-1.51ppm, $PO_4$-P 2.50-17.28ppm. 2) At Kongdan cheon, the most heavily polluted site, average values of components were pH 8.2, DO trace, COD 116.9ppm, T-N 23.2ppm, $NH_4$-N 18.3ppm, $NO_2$-N 1.89ppm, $NO_3$-N 1.51ppm, $PO_4$-P 17.28ppm. 3) The values of pH, DO, COD, T-N and $NH_4$-N at winter urban streams were higher than those at summer urban streams. And the values of $NO_2$-N and $PO_4$-P were more or less higher at summer urban streams.