• Korean Journal of Ecology and Environment
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• v.33 no.1 s.89
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• pp.51-60
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• 2000

In order to understand the trend and assessment of water pollution, seasonal water quality was determined in the main river and the tributaries from midstream to downstream of the Kum River from March 1998 to June 1999. Among environmental factors, the variation of nitrogen, phosphorus and chlorophyll-a was distinctive on an aspect of increase and decrease relatively to others, and particularly the impact of inorganic N ${\cdot}$ P inflowing into the main river was observed to be more significant at the Kapchon, Mihochon and Soksongchon among the tributaries. Water quality was highly related to hydrologic factor, and it was more deteriorated when water discharge maintains for a long time below normal flow or relatively at low condition of minimum and drought flow. These phenomena were remarkablee from December to March of the next year. $NH_4$ and SRP were decreased dramatically flowing toward the lower part of the river and chl-a was increased exponentially. While, the variations of $NO_3$ and $BOD_5$ were regular from midstream to downstream and there was no significant difference between the stations. Limiting nutrient for Phytoplankton growth seemed to be P than N because the ratio of TN/TP or DIN/SRP was relatively high as 42 or 544 in the main river, respectively. The main river and tributaries were ranked to be third grade, based on the assessment of BOD as an indirect indicator of organics, but particularly Kapchon was ranked to be over fifth grade. In addition, the inflow of high N ${\cdot}$ P nutrients from tributaries including Kapchon and Mihochon seemed to be major factor of the development of water pollution of the Kum River. On the other hand, persistent bloom of phytoplankton in lower part of the river was observed. As a conclusion, management of water quality for main source of pollution is urgent.

• Journal of The Korean Society of Grassland and Forage Science
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• v.3 no.2
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• pp.67-76
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• 1983

This experiment was carried out to investigate the effects of the different nitrogen rates and cutting heights on the dead stubble after cutting, and the carbohydrate reserved in stubble of sorghum-sudangrass hybrid (Sorghum bicolor (L.) Moench) Pioneer 988. The experiment was undertaken in the Experimental Livestock Farm of Agriculture Coll., Seoul Nat'l Univ. In Suweon, 1981 and 1982. The results obtained are summarized as follows: 1. The dead stubble after cutting was found to be great with high rate of nitrogen fertilizer and low cutting height. It was also learned that the rainfall during forage cutting period made the dead stubble increased. 2. A significant higher (p<0.05) carbohydrate reserves in the stubble was observed in the high stubble height at the first cutting time and 6th through 7th day after the first cutting. The results indicate that the high stubble height reserves more carbohydrate for the early regrwoth stage after the first cutting when comparing with the low stubble. 3. The content of carbohydrate reserves was influenced by climete. Drought is caused to high content of carbohydrate, whereas, rain is caused to low content of that. The critical soluble carbohydrate content causing the death of stubble supposed to be 3 to 6% at least. 4. It is suggest that carbohydrate reserves in plant do not play a distinctive role for the regrowth in a summer annual forage like sorghum-sudangrass hybrid, but it might be rather influenced by the other factors, for example, environmental conditions at harvest and new bud.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1235-1247
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• 2013

This study is to evaluate the climate change impact on future storage behavior of Chungju dam($2,750{\times}10^6m^3$) and the regulation dam($30{\times}10^6m^3$) using SWAT(Soil Water Assessment Tool) model. Using 9 years data (2002~2010), the SWAT was calibrated and validated for streamflow at three locations with 0.73 average Nash-Sutcliffe model Efficiency (NSE) and for two reservoir water levels with 0.86 NSE respectively. For future evaluation, the HadCM3 of GCMs (General Circulation Models) data by scenarios of SRES (Special Report on Emission Scenarios) A2 and B1 of the IPCC (Intergovernmental Panel on Climate Change) were adopted. The monthly temperature and precipitation data (2007~2099) were spatially corrected using 30 years (1977~2006, baseline period) of ground measured data through bias-correction, and temporally downscaled by Change Factor (CF) statistical method. For two periods; 2040s (2031~2050), 2080s (2071~2099), the future annual temperature were predicted to change $+0.9^{\circ}C$ in 2040s and $+4.0^{\circ}C$ in 2080s, and annual precipitation increased 9.6% in 2040s and 20.7% in 2080s respectively. The future watershed evapotranspiration increased up to 15.3% and the soil moisture decreased maximum 2.8% compared to baseline (2002~2010) condition. Under the future dam release condition of 9 years average (2002~2010) for each dam, the yearly dam inflow increased maximum 21.1% for most period except autumn. By the decrease of dam inflow in future autumn, the future dam storage could not recover to the full water level at the end of the year by the present dam release pattern. For the future flood and drought years, the temporal variation of dam storage became more unstable as it needs careful downward and upward management of dam storage respectively. Thus it is necessary to adjust the dam release pattern for climate change adaptation.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.238-246
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• 2018

Purpose: The purpose of this study is to examine the directions for establishing a disaster safety village in rural areas where damage from a similar type of disaster occurs repeatedly by conducting the consciousness survey targeting at experts and disaster safety officials in a local government. Method: The risks of disaster in rural areas were examined and the concept and characteristics of disaster safety village which is a measure on the basis of Myeon (township) among the measures of village unit were examined in order to carry out this study. In addition, opinion polling targeting at officials-in-charge in the local government and survey targeting at experts in disaster safety and building village were conducted. Based on the findings, the directions for establishing a disaster safety village that fitted the characteristics of rural areas were examined. Result: The officials-in-charge in the local government answered that rural areas have a high risk of storm and flood such as heavy snowing, typhoon, drought, and heavy rain as well as forest fire, and it is difficult to draw voluntary participation of farmers for disaster management activities due to their main duties. They also replied that active support and participation of residents in rural areas are necessary for future improvement measures. The experts mostly replied that the problem of disaster safety village project is a temporary project which has low sustainability, and the lack of connections between the central government, local governments and residents was stressed out as the difficulties. They said that measures to secure the budget and the directions of project promotion system should be promoted by the central government, local governments and residents together. Conclusion: The results of this study are as follows. First, a disaster safety village should be established in consideration of the disaster types and characteristics. Second, measures to secure the budget for utilizing the central government fund as well as local government fund and village development fund should be prepared when establishing and operating a disaster safety village in rural areas. Third, measures to utilize a disaster safety village in rural areas for a long period of time such as the re-authorization system should be prepared in order to continuously operate and manage such villages after its establishment. Fourth, detailed measures that allow residents of rural areas to positively participate in the activities for establishing a disaster safety village in rural areas should be prepared.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.354-374
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• 2016

This study explored spatiotemporal variability of water quality in correspondence with hydrometeorological factors in the five stations of Paldang Reservoir located in the Han River during 4 years from May 2012 to December 2015. Variability of basic water quality factors were largely related with seasonal fluctuations of hydrology. Temperature stratification occurred in the deep dam station, and prolonged hypoxia was observed during the draught year. Nitrogen nutrients were increased with decreasing inflow in which changing pattern of $NH_4$ reversed to $NO_3$ by the effect of treated wastewater effluent. Phosphorus increase was manifest during the period of high inflow or severe drought. Chl-a variation was reversely related with both flow change and AGP(algal growth potential) variations. Our study demonstrated that water quality variability in Paldang Reservoir was largely attributed to both natural and operational changes of inflow and outflow (including water intake) based on major pollution source of the treated wastewater (total amount of $472{\times}10^3m^3d^{-1}$) entering to the water system from watershed. In the process of water quality variability, meteorological (e.g., flood, typhoon, abnormal rainfall, scorching heat of summer) and hydrological factors (inflow and discharge) were likely to work dynamically with nutrients pulse, dilution, absorption, concentration and sedimentation. We underline comprehensive limnological study related to hydro-meteorolology to understand short- and long-term water quality variability in river-type large reservoir and suggest the necessity of P-free wastewater treatment for the effective measure of reducing pollution level of Paldang drinking water resource.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.2
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• pp.109-114
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• 2016

This study was conducted to determine grazing intensity of growing Korean native goats (Capra hircus coreanae) on mountainous pasture. It was carried out to obtain basic information for improvement of mountainous pasture management and establishing feeding system of Korean native goats. Castrated, male goats (n=10) with average initial body weight (BW) of $23.33{\pm}2.15kg$ and an average age of 4 months were used in this study. Grazing goats were supplemented by concentrates with 1.0% of BW. The crude protein content of forage was the highest in October ($22.71{\pm}0.25%$) and there were significantly differences (p<0.05) in monthly comparison. The forage productivity of pasture was the highest from May to June ($1718.7{\pm}207.5{\sim}1672.0{\pm}422.8kg/ha$ but it was decreased in July ($1356.0{\pm}103.8kg/ha$) because of drought and summer depression. Average daily gains (ADG) of goats were the highest in June ($99.5{\pm}6.4d/g$). Grazing intensity was calculated by forage productivity and dry matter intake (DMI) and was the highest in May (65 head/ha). As shown in the results of this research, grazing intensity was suggested to average 39 head/ha from May to October. It is desirable that adequate grazing intensity was maintained by adjusting supplemental feed.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.331-344
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• 2009

Buffalograss is an important turfgrass species with excellent cold, heat, and drought tolerance. Understanding the physiological integration of buffalograss under heterogeneous conditions helps to develop cultural practices that better use limited resources for uniform turf quality. The objective of this study was to evaluate physiological integration of buffalograss under water deficit stress and the involvement of lipid peroxidation and antioxidants in the process. In one experiment, buffalograss was planted in the center of a four-compartment growth unit. Watering frequencies, once a week(+) and once in two weeks(-), were combined with the sand(S) or peat(P) in each unit to generate five total treatments(P+S-P-S+, P+P+P+P+, S-S-S-S-, P-P-P-P-, and S+S+S+S+). The average number of shoot established from the heterogeneous root-zone medium was higher than the average of four possible homogeneous media. In second experiment, single ramet in Hoagland solution($S_0$) or single ramet in Hoagland solution with 20% PEG-6000($S_s$) were compared with two connectedramets under different treatments. Treatments for connected ramets were young ramet in Hoagland solution($Y_{os}$) and old ramet in Hoagland solution with 20% PEG-6000($O_{os}$), and old ramet in Hoagland solution($O_{ys}$) and young ramet in Hoagland solution with 20% PEG-6000($Y_{ys}$). Lipid peroxidation, antioxidants, and proline showedphysiological integration between ramets subjected to different levels of water stress. Superoxide dismutase(SOD), Guaiacol peroxidase(G-POD), malondialdehyde(MDA), and free proline also showed different time courses and relative activities during the physiological integration.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.161-176
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• 2021

In this study, one of the distributed hydrologic models, VELAS, was used to analyze the variation of hydrologic elements based on water balance analysis to evaluate the groundwater recharge in more detail than the annual time scale for the past and future. The study area is located in Yanggok-ri, Seobu-myeon, Hongseong-gun, Chungnam-do, which is very vulnerable to drought. To implement the VELAS model, spatial characteristic data such as digital elevation model (DEM), vegetation, and slope were established, and GIS data were constructed through spatial interpolation on the daily air temperature, precipitation, average wind speed, and relative humidity of the Korea Meteorological Stations. The results of the analysis showed that annual precipitation was 799.1-1750.8 mm, average 1210.7 mm, groundwater recharge of 28.8-492.9 mm, and average 196.9 mm over the past 18 years from 2001 to 2018 in the study area. Annual groundwater recharge rate compared to annual precipitation was from 3.6 to 28.2% with a very large variation and average 14.9%. By the climate change RCP 8.5 scenario, the annual precipitation from 2019 to 2100 was 572.8-1996.5 mm (average 1078.4 mm) and groundwater recharge of 26.7-432.5 mm (average precipitation 16.2%). The annual groundwater recharge rates in the future were projected from 2.8% to 45.1%, 18.2% on average. The components that make up the water balance were well correlated with precipitation, especially in the annual data rather than the daily data. However, the amount of evapotranspiration seems to be more affected by other climatic factors such as temperature. Groundwater recharge in more detailed time scale rather than annual scale is expected to provide basic data that can be used for groundwater development and management if precipitation are severely varied by time, such as droughts or floods.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.71-80
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• 2019

Effects of environmental factors on phytoplankton succession and community structure were studied in Lake Chuncheon located in Bukhan River, South Korea. The data were sampled at three sites such as CC1 (lower side), CC2 (middle side), and CC3 (upper side of Lake Chuncheon) from 2014 to 2017. The annual average precipitation in Lake Chuncheon was 992 mm during the study period (2014~2017), and the annual precipitation was lower than 800 mm in 2014 and 2015. The annual average water temperature, total phosphorus (TP), and total nitrogen (TN) ranged from 17.0 to $21.1^{\circ}C$, 0.012 to $0.019mg\;L^{-1}$, and 1.272 to $1.922mg\;L^{-1}$, respectively. The TN concentration was relatively high in 2015 compared with the other study years, as a drought continued from 2014 to 2015. When comparing the correlation between precipitation and environmental factors, water temperature (p<0.01) and TP(p<0.05) showed positive correlations with rainfall. The average numbers of phytoplankton cells by branch were 2,094, 2,182, and $3,108cells\;mL^{-1}$ in CC1, CC2, and CC3, respectively. CC3 is considered advantageous for phytoplankton growth, even in small pollution sources due to low water depth. As a result of analyzing the relationship between precipitation and phytoplankton, the correlation between the two was shown to be high for 2016 (p<0.01) and 2017 (p<0.05), which is when precipitation was high. However, the correlation was not clear to 2014 and 2015. The relationship between water temperature and phytoplankton indicated a negative correlation with diatoms (p<0.01), yet positive correlations with green algae (p<0.01) and cyanobacteria (p<0.01). Diatoms increased in spring and autumn, which are characterized by low water temperature, and green algae and cyanobacteria increased in summer, when the water temperature is high. Our findings provide a scientific basis for characteristics of phytoplankton and water quality and management at the Lake Chuncheon.

• Journal of Korea Water Resources Association
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• v.57 no.1
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• pp.1-8
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• 2024

Persistent droughts due to climate change will intensify water shortage problems in Korea. According to the 1st National Water Management Plan, the shortage of domestic and industrial waters is projected to be 0.07 billion m³/year under a 50-year drought event. A long-term prediction of water demand is essential for effectively responding to water shortage problems. Unlike industrial water, which has a relatively constant monthly usage, domestic water is analyzed on monthly basis due to apparent monthly usage patterns. We analyzed monthly water usage patterns using water usage data from 2017 to 2021 in Chungcheong, South Korea. The monthly water usage rate was calculated by dividing monthly water usage by annual water usage. We also calculated the water distribution rate considering correlations between water usage rate and climate variables. The division method that divided the monthly water usage rate by monthly average temperature resulted in the smallest absolute error. Using the division method with average temperature, we calculated the water distribution rates for the Chungcheong region. Then we predicted future water usage rates in the Chungcheong region by multiplying the average temperature of the SSP5-8.5 scenario and the water distribution rate. As a result, the average of the maximum water usage rate increased from 1.16 to 1.29 and the average of the minimum water usage rate decreased from 0.86 to 0.84, and the first quartile decreased from 0.95 to 0.93 and the third quartile increased from 1.04 to 1.06. Therefore, it is expected that the variability in monthly water usage rates will increase in the future.