• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.3
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• pp.35-49
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• 2014

In this study, the faunae before and after creating the Solbangjuk Wetland Ecological Park located in Jecheon-city were compared. As a result, the change of the fauna according to the creation of the park showed the phenomenon that the species having the strong wilderness are reduced and the rate of general species become higher. In addition, the species which receive the restrictions for moving such as mammals, amphibians and reptiles are being gradually decreased by the increased visitors owing to the creation of the park. Moreover because there was the case where group of fishes have died caused by discharging and working the water in the reservoir during the creation process of the park, the supplementation work for this is required. However, it showed that the insects sucking the honey from flowers in the composed flower garden after creating the park, and the aquatic insects which live in this park that the stable water system for the growth of wetland plants is maintained, are increased, respectively. As a result of this survey, because the reservoir for agriculture adjacent to the residential area is generally small, the securing of the habitat space for the wild animals living in this park when creating the ecological parks seems to be necessary. The countermeasure should be considered so that some areas of the reservoir can be maintained in their natural state by adjusting the visitors' trails and the position of facilities for in order to secure the habitat of the wild animals.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.15-21
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• 1996

Effects of acid deposition on the acidification of surface water over a short term period were studied during June~October, 1995. A reservoir located in Chunchon, Kangwondo was selected for this study because this reservoir had received little man-made pollutants. Geological survey within the study area was carried out and the pH of a small and shallow stream flowing from the mountain valley down to the reservoir was monitored. Rainfall was measured by using a rain gauge and the precipitation was collected by automatic precipitation sampler. During the study period, rain pH was in the range of 3.81~5.77 with an average of 4.8. The EC was in the range of 5~189$\mu$S/cm with an average of 10.6$\mu$S/cm. ionic composition of the rainfall showed that of the anions, deposition of ${SO_4}^{2-}$, was highest with 3,119.7 kg/$\textrm{km}^2$, and it was $NH^{4+}$ with 1,053.2kg/$\textrm{km}^2$ for cations. The surface water pHs were maintained neutral or weak basic representing little evidence of acidification regardless of the acidic rainfall pH. Every time of sampling, however, the pHs exhibited increasing tendency as elevation of measuring site of the stream became lowered, which indicated the impacts of acid-base reactions by acidic or basic substances during travel of water downstream. This result suggested the necessity of further research to determine the respective buffering capacity of soil and underlying rocks.

• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.337-379
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• 2005

This choice experiments study values the non-market benefits of water quality improvements in Paldang Reservoir and Han River, located in Korea. A fractional factorial orthogonal design was used to produce four different choice sets per respondent, before employing choice examples to screen out irrational responses. The panel mixed logit model (with normal distributions for the attributes) fit the data best, indicating that allowing for both heterogeneous preferences across households and correlation between repeated choices may represent actual choice behaviors best of all the estimated models. The significant standard deviations of the random attributes suggest that the taste for each attribute may vary considerably in the population. The annual benefits to the Seoul Metropolitan area for a small (large) enhancement of the clarity of water, a gradual removal of unpleasant waters, and a gradual improvement in biodiversity, were estimated to be some 1.5 trillion (1.7 trillion) Won, 2 trillion Won, and 1.7 trillion Won, respectively, with 1.8~2.6 trillion Won for at least two of them occurring together. The study also discusses potential biases germane to choice experiments studies of this type.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.236-244
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• 2006

Water quality fluctuation of Gyeongan water area in Paldang reservoir, which measured from the downstream sampling point of Gyeongan stream (G1) to dam sampling point (P), was examined in the light of seasonal rainfall and regional difference in the year of 2002. Annual COD, T-P and T-N concentration dropped conspicuously at the point P (in front of dam) although concentration of Gl point was high. Concentration variation of COD, T-P and T-N from Gl to P point in Gyeongan area was small in August and September. And at G l point showed relatively low concentration. Chlorophyll-a concentration varies less during the autumn season (October to December) than spring season (March to June). Water temperature of Bughangang (north Han-river) area was relatively lower in August and higher in November compared with that of other areas. COD and SS concentration showed big regional difference except in November when the concentrations of which were relatively low. The high Chlorophyll-a concentration of April fell conspicuously in rainy season. Gyeongan area, where the water depth is relatively shallow, indicated steep temperature gradient in April compared with that in August or November. High 55 concentration in April at P point characterized surface layer while the opposite was recorded in August. Mixing of upper and lower layers had taken place causing dilution of COD, T-N and T-P concentration in August. This condition was maintained throughout November. Therefore, spring-summer seasons needed more attention for water management countermeasure than summer-autumn seasons.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.213-226
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• 2004

The present study was conducted to analyze the pattern of eutrophication of Korean reservoir with Chl. a concentration and morpho-physical parameters, and to valuate water quality characteristics of the classified types. The collected data from 486 reservoirs were classified as four types, with the Chl- a concentration (25 ${\mu}g\;L^{-1}$) and the ratio of water storage/surface area (mean depth, 7.5 m). According to OECD criteria and trophic state index based on Chl-a concentration, 34.3 and 72.8% of selected reservoirs appeared to be eutrophic, respectively. Characteristics of TYPE ll reservoirs generally showed high Chl-a concentration, relatively old age, small DA/LA ratio, short Hydraulic retention time, large paddy field and field to watershed ratio, and high pollutant loading compared to other types of reservoirs. The difference of TP concentration was greater than that of TN concentration in reservoir water among classified four types. Based on TN/TP ratio (by weight), phosphorus was limiting nutrient in all types and more closely related with Chl- a concentration than nitrogen. Significant decrease of Chl- a concentration with increase of TN/TP ratio observed only in reservoirs with Chl-a concentration > 25${\mu}g\;L^{-1}$. Although drainage area is believed to be a factor that is related to the generation load of pollutants in the watershed, it did not show any significant relationship with water quality parameters. Morphometric characteristics such as depth and age of reservoir as well as type of land use patterns in the watershed was among important parameters for the assessment of water quality characteristics in Korean reservoirs.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.237-249
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• 2011

The purpose of this study was to monitor the streamflow of rural streams for investigating the status of stream depletion located downstream of irrigation reservoir. Bonghyun and Hi reservoirs area, located in Gyeongnam, Gosung-gun, Hi-myeon, were selected for study watersheds and streams. Streamflow monitoring were conducted 6 times during the paddy growing season of 2010 from May to October. Streamflow was measured for 18 stations downstream from two reservoirs with the interval of 300m to 500m, The amount of streamflow were highly dependent on the antecedent precipitation and irrigation amount. In most observation stations, streamflow was depleted when precipitation and irrigation were not provided. Pumping from stream for irrigation and water supply for factory and irrigation return flow were also factors on streamflow. Continuous monitoring for rural streams located in downstream of reservoirs are required to quantify the status of streamflow depletion and determine the amount of environmental flows.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.427-435
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• 2021

An analysis considering the fluid-structure interaction is required to strictly evaluate the seismic behavior of facilities such as, environmental facilities and dams, that store fluids. Specifically, in the case of an infinite domain in the upstream direction, such as a dam-reservoir system, this should be carefully considered. In this study, we proposed a practical numerical model for both wave propagation and fluid-structure interaction analyses of an infinite domain, for a system with a semi-infinite domain such as a dam-reservoir system. This method was applicable to the time domain, and enabled accurate boundary analysis. For an infinite fluid domain, a small number of mid-point integrated acoustic finite elements were applied instead of a general acoustic finite element, and a viscous boundary was imposed on the outermost boundary. The validity and accuracy of the proposed method were secured by comparing analytic solutions of a reservoir having infinite domain, with the parametric analysis results, for the number of elements and the size of the modeling region. Furthermore, the proposed method was compared with other fluid-structure interaction methods using additional mass.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.3
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• pp.9-24
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• 2022

Currently, a vast amount of hydrologic data is accumulated in real-time through automatic water level measuring instruments in agricultural reservoirs. At the same time, false and missing data points are also increasing. The applicability and reliability of quality control of hydrological data must be secured for efficient agricultural water management through calculation of water supply and disaster management. Considering the characteristics of irregularities in hydrological data caused by irrigation water usage and rainfall pattern, the Korea Rural Community Corporation is currently applying the Hampel filter as a water level data quality management method. This method uses window size as a key parameter, and if window size is large, distortion of data may occur and if window size is small, many outliers are not removed which reduces the reliability of the corrected data. Thus, selection of the optimal window size for individual reservoir is required. To ensure reliability, we compared and analyzed the RMSE (Root Mean Square Error) and NSE (Nash-Sutcliffe model efficiency coefficient) of the corrected data and the daily water level of the RIMS (Rural Infrastructure Management System) data, and the automatic outlier detection standards used by the Ministry of Environment. To select the optimal window size, we used the classification performance evaluation index of the error matrix and the rainfall data of the irrigation period, showing the optimal values at 3 h. The efficient reservoir automatic calibration technique can reduce manpower and time required for manual calibration, and is expected to improve the reliability of water level data and the value of water resources.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.285-293
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• 2022

Sampling gears for collecting fish are diverse, and the community of fish varies according to the selection and characteristics of the sampling gears. The present study compared the characteristics of fish communities in Yedang reservoir using four sampling gears (kick net, cast net, gill net, and fyke net). The kick net and cast net were inefficient in collecting the number of individuals. However, they increased the species diversity of fish inhabiting the waterfront. Although not many individuals were collected, the gill net mainly collected large fish. The largest number of individuals was collected in the fyke net, and the dominance was high due to the high species selectivity. Through Self-Organizing Map (SOM) analysis, large fish were collected in the gill net, whereas small fish were collected in the fyke net. The characteristics and efficiency of the fish differed depending on the sampling gears. It is expected that researchers will need to use it appropriately according to the characteristics of the sampling gears when investigating the fish community.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.349-357
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• 2017

If an actuation system of the tactical missile is required very fast response time on conditions of short operating time and big loads on the actuator, we would prefer to adopt a small hydraulic system. In this paper, a mathematical model is proposed to analyze and simulate the small hydraulic actuation system. The mathematical model consists of a high pressure vessel model, a pressure regulator model, a hydraulic reservoir model and a actuator model. The suggested model is validated by comparison of simulation results with experimental data. The simulation results show that the mathematical model could be useful for designing a hydraulic actuation system.