• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.4
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• pp.63-72
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• 2018

The main function of an agricultural reservoir is to supply irrigation water to paddy rice fields in South Korea. Therefore, the operation of a reservoir is significantly affected by the phenology of paddy rice. For example, the early stage of irrigation season, a lot of irrigation water is required for transplanting rice. Therefore, water storage in the reservoir before irrigation season can be a key factor for sustainable irrigation, and it becomes more important under climate change situation. In this study, we analyzed the climate change impacts on reservoir storage rate at the beginning of irrigation period and simulated the reservoir storage, runoff, and irrigation water requirement under RCP scenarios. Frequency analysis was conducted with simulation results to analyze water supply probabilities of reservoirs. Water supply probability was lower in RCP 8.5 scenario than in RCP 4.5 scenario because of low precipitation in the non-irrigation period. Study reservoirs are classified into 5 groups by water supply probability. Reservoirs in group 5 showed more than 85 percentage probabilities to be filled up from half-filled condition during the non-irrigation period, whereas group 1 showed less than 5 percentages. In conclusion, reservoir capacity to catchment area ratio mainly affected water supply probability. If the ratio was high, reservoirs tended to have a low possibility to supply enough irrigation water amount.

• Journal of Korean Academy of Rural Health Nursing
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• v.4 no.1
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• pp.5-12
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• 2009

Purpose: The purpose of this study was to describe the prevalence of clonorchiais and analyze the knowledge level and intention of the participants to change their behavior related to clonorchiais. Method: The participants were 514 people from 7 community health posts along the Geum River. The formalin-esther sedimentation technique was used to detect the Clonorchis Sinensis (CS) eggs and a questionnaire for data on related factors. The study was carried on from December 2008 to January 2009. Results: The prevalence of CS averaged 9.3%, with a range from 0% to 24.6%. The significant factors were sex, habit of eating raw fish, and habit related to smoking and alcohol consumption. The level of knowledge was not high and not significantly different between the CS positive group and CS negative group. Intention to change their habits of eating raw fish showed various stages of change and attitudes to raw fish eating habit of others were not positive. Conclusions: These results suggest that a CS control program needs to be developed by community health services in the Geum River area to decrease the prevalence of clonorchiais.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.524-528
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• 2009

The objectives of this study were to install RCR systems at a typical single family house and a school in Alabama, and evaluate the feasibility and efficiency of using the RCR systems for water harvesting in Alabama. The RCR systemswere equipped with a control system and a CR10X data logger to monitor the system operation and to collect data on precipitation, temperature, overflow, water depth in the storage tank and daily uses of toilet flushing. Daily average water use of the home for toilet flushing was 95 liter and 2100 liter was used at the school during the school days. Rainwater harvesting efficiency was 83.3 and 89 percent and RCR use efficiency was 18 and 98 percent from the home and the school, respectively. A computer program was developed to estimate potential effectiveness of RCR systems. From the analysis result with 10 years rainfall data, a total of 67,000 liters of rainwater could be harvested for domestic uses from a typical single family house which supplies 190 liters per day.

• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.945-958
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• 2014

Soil temperature is one of the most important environmental factors that govern hydrological and biogeochemical processes related to diffuse pollution. In this study, considering the snowmelting and the soil freezing-thawing processes, a set of computer codes to estimate winter soil temperature has been developed for CAMEL (Chemicals, Agricultural Management and Erosion Losses), a distributed watershed model. The model was calibrated and validated against the field measurements for three months at 4 sites across the study catchment in a rural area of Yeoju, Korea. The degree of agreement between the simulated and the observed soil temperature is good for the soil surface ($R^2$ 0.71~0.95, RMSE $0.89{\sim}1.49^{\circ}C$). As for the subsurface soils, however, the simulation results are not as good as for the soil surface ($R^2$ 0.51~0.97, RMSE $0.51{\sim}5.08^{\circ}C$) which is considered resulting from vertically-homogeneous soil textures assumed in the model. The model well simulates the blanket effect of snowpack and the latent heat flux in the soil freezing-thawing processes. Although there is some discrepancy between the simulated and the observed soil temperature due to limitations of the model structure and the lack of data, the model reasonably well simulates the temporal and spatial distributions of the soil temperature and the snow water equivalent in accordance with the land uses and the topography of the study catchment.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.18-18
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• 2011

Climate change is impacting and will increasingly impact both the quantity and quality of the world's water resources in a variety of ways. In some areas warming climate results in increased rainfall, surface runoff, and groundwater recharge while in others there may be declines in all of these. Water quality is described by a number of variables. Some are directly impacted by climate change. Temperature is an obvious example. Notably, increased atmospheric concentrations of $CO_2$ triggering climate change increase the $CO_2$ dissolving into water. This has manifold consequences including decreased pH and increased alkalinity, with resultant increases in dissolved concentrations of the minerals in geologic materials contacted by such water. Climate change is also expected to increase the number and intensity of extreme climate events, with related hydrologic changes. A simple framework has been developed in New Zealand for assessing and predicting climate change impacts on water resources. Assessment is largely based on trend analysis of historic data using the non-parametric Mann-Kendall method. Trend analysis requires long-term, regular monitoring data for both climate and hydrologic variables. Data quality is of primary importance and data gaps must be avoided. Quantitative prediction of climate change impacts on the quantity of water resources can be accomplished by computer modelling. This requires the serial coupling of various models. For example, regional downscaling of results from a world-wide general circulation model (GCM) can be used to forecast temperatures and precipitation for various emissions scenarios in specific catchments. Mechanistic or artificial intelligence modelling can then be used with these inputs to simulate climate change impacts over time, such as changes in streamflow, groundwater-surface water interactions, and changes in groundwater levels. The Waimea Plains catchment in New Zealand was selected for a test application of these assessment and prediction methods. This catchment is predicted to undergo relatively minor impacts due to climate change. All available climate and hydrologic databases were obtained and analyzed. These included climate (temperature, precipitation, solar radiation and sunshine hours, evapotranspiration, humidity, and cloud cover) and hydrologic (streamflow and quality and groundwater levels and quality) records. Results varied but there were indications of atmospheric temperature increasing, rainfall decreasing, streamflow decreasing, and groundwater level decreasing trends. Artificial intelligence modelling was applied to predict water usage, rainfall recharge of groundwater, and upstream flow for two regionally downscaled climate change scenarios (A1B and A2). The AI methods used were multi-layer perceptron (MLP) with extended Kalman filtering (EKF), genetic programming (GP), and a dynamic neuro-fuzzy local modelling system (DNFLMS), respectively. These were then used as inputs to a mechanistic groundwater flow-surface water interaction model (MODFLOW). A DNFLMS was also used to simulate downstream flow and groundwater levels for comparison with MODFLOW outputs. MODFLOW and DNFLMS outputs were consistent. They indicated declines in streamflow on the order of 21 to 23% for MODFLOW and DNFLMS (A1B scenario), respectively, and 27% in both cases for the A2 scenario under severe drought conditions by 2058-2059, with little if any change in groundwater levels.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.2
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• pp.76-84
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• 2013

An adequate downscaling of the official forecasts of Korea Meteorological Administration (KMA) is a prerequisite to improving the value and utility of agrometeorological information in rural areas, where complex terrain and small farms constitute major features of the landscape. In this study, we suggest a simple correction scheme for scaling down the KMA temperature forecasts from mesoscale (5 km by 5 km) to the local scale (30 m by 30 m) across a rural catchment, especially under temperature inversion conditions. The study area is a rural catchment of $50km^2$ area with complex terrain and located on a southern slope of Mountain Jiri National Park. Temperature forecasts for 0600 LST on 62 days with temperature inversion were selected from the fall 2011-spring 2012 KMA data archive. A geospatial correction scheme which can simulate both cold air drainage and the so-called 'thermal belt' was used to derive the site-specific temperature deviation across the study area at a 30 m by 30 m resolution from the original 5 km by 5 km forecast grids. The observed temperature data at 12 validation sites within the study area showed a substantial reduction in forecast error: from ${\pm}2^{\circ}C$ to ${\pm}1^{\circ}C$ in the mean error range and from $1.9^{\circ}C$ to $1.6^{\circ}C$ in the root mean square error. Improvement was most remarkable at low lying locations showing frequent cold pooling events. Temperature prediction error was less than $2^{\circ}C$ for more than 80% of the observed inversion cases and less than $1^{\circ}C$ for half of the cases. Temperature forecasts corrected by this scheme may accelerate implementation of the freeze and frost early warning service for major fruits growing regions in Korea.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.99-106
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• 2007

This study was focused on understanding the agricultural non-point sources pollution in 72 rural catchments of Nakdong river watershed from 2001 to 2005 every two year. Also. Pearson correlations between water quality and basin characteristic were computed. Water quality of this study watershed was better in 2003 than any other period. The water quality of upstream was recorded from 0.040 to 0.510 dS/m in EC, from 3.55 to 22.60 mg/L in DO, from 0.32 to 16.64 mg/L in T-N, from 0.00 to 12.21 mg/L in $NO_3-N$, from 0.000 to 0.860 mg/L in T-P, and from 0.000 to 0.640 mg/L in $PO_4-P$. A the downstream, EC was measured from 0.030 to 0.520 dS/m, DO from 4.13 to 18.36 mg/L, T-N from 0.38 to 26.88 mg/L, $NO_3-N$ from 0.10 to 20.12 mg/L, T-P from 0.002 to 0.820 mg/L, $PO_4-P$ from 0.002 to 0.690 mg/L. But there was no difference between upstream and downstream for the water quality. Based on the correlation analysis between water quality and land use, correlation between BOD and residential was the highest positive correlation of 0.541 (p<0.01), and correlation between $PO_4-P$ and forest was the highest negative correlation of -0.451 (p<0.01). Also, T-N, $NO_3-N$, and pH were not correlated with all basin characteristics and basin was not correlated with all water quality parameter. According to the correlation residential was causative of growing worst for water quality, and forest was causative of improving for water quality.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.47-55
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• 2007

The waste water treatment facility at rural and mountainous region in catchment areas of dams should be small scale. The wastewater treatment facility of small scale has some specification as follows;1)simple process, 2)low maintenance cost, and 3)high removal efficiency. So, we developed the bioreactor which can be satisfied with the specification of small scale waste water treatment facility. The bioreactor consisted of the anoxic and oxic zone. The two zones were effectively separated by cone type baffle. By the effective separation through CTB, the nitrification and denitrification reaction occurred effectively. Therefore, the removal efficiency of total nitorgen (TN) increased compared to other types of baffle. And, we put into the bio activated media in oxic zone to increase the concentration and activity of microbiology. The media contained the components which were made of many kinds of the minerals to increase the activity of microbiology. Additionally, we observed that the phosphate removal efficiency increased by bio activated media. This is resulted from the coagulation-sedimentation reaction by mineral in components. The average removal efficiencies of TN and TP during Run 2 were 69 and 89% which were 4 and 25% higher than those during Run 1 without the MA, respectively. For BOD, COD, SS and TKN, the average removal efficiencies at Run 2 were slightly higher than those at Run 1. Therefore, we could maintain the high concentration and high activity of microbiology through bioreactor developed in this study. And the removal efficiency of TN and TP increased.

• Journal of Korea Water Resources Association
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• v.32 no.6
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• pp.711-720
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• 1999

In this study, a various rainfall-runoff modelling approaches have been applied to the runoff response of flood hydrograph in three experimental watershed of the western part of korea. Mathematical models of runoff response also have been studied including linear system theory based on modeling techniques. Eight models were operated at the five water level gauging stations and the parameters of each model were computed by the Rosenbrock's hill climbing method to minimize the objective function. For the parameter verification of the models, a different complex rainfall-runoff event was selected in the same of the three river basins and derived IUH of the each model could be calibrated. Furthermore multiple regressions of the logarithmic transformation method between model parameters and catchment characteristics were studied in the selected five station.

• Journal of Climate Change Research
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• v.8 no.2
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• pp.171-175
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• 2017

The purpose of the farmstead-specific early warning service system for weather risk management is to develop custom-made risk management recommendations for individual farms threatened by climate change and its variability. This system quantifies weather conditions into a "weather risk index" that is customized to crop and its growth stage. When the risk reaches the stage where it can cause any damage to the crops, the system is activated and the corresponding warning messages are delivered to the farmer's mobile phone. The messages are sent with proper recommendations that farmers can utilize to protect their crops against potential damage. Currently, the technology necessary to make the warning system more practical has been developed, including technology for forecasting real-time weather conditions, scaling down of weather data to the individual farm level and risk assessments of specific crops. Furthermore, the scientific know-how has already been integrated into a web-based warning system (http://new.agmet.kr). The system is provided to volunteer farmers with direct, one-on-one weather data and disaster warnings along with relevant recommendations. In 2016, an operational system was established in a rural catchment ($1,500km^2$) in the Seomjin river basin.