• Ecology and Resilient Infrastructure
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• v.5 no.2
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• pp.94-104
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• 2018

The Soyangho Reservoir in Korea has a large drawdown zone, with an annual maximum water level fluctuation of 37 m due to dam operations to maintain a stable water supply and control flooding, especially during the monsoon period. The floristic composition, distribution and biomass of the major plant communities in the drawdown zone of the Soyangho Reservoir were assessed in order to understand their responses to the wide water level fluctuation. Species richness of vascular plants was low, and species composition was dominated by herbaceous annuals. Principal coordinates analysis using both flora and environmental data identified slope angle and the distance from the dam as important factors determining floristic composition. The species richness was low in the steep drawdown zone close to the dam, where much of the soil surface was almost devoid of vegetation. In shallower slopes, distant from the dam plant communities composed of mainly annuals were found. The large fluctuation in water level exposed soil where these annuals could establish. An overall biomass of 122 t (metric tons) Dry Matter was estimated for the reservoir, containing ca 3.6 t N (nitrogen) and ca 0.3 t P (phosphorus); the role of the vegetation of the drawdown zone in carbon sequestration and water pollution were briefly discussed.

• Water for future
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• v.27 no.3
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• pp.83-83
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• 1994

The major objective of this study is to analyze the water balance of the Keumgang Estuary Reservoir in the Keum River basin. This basin is one of the catchment area which water utilization is very complicated. For the study of this area, this paper is to evaluate the monthly river-inflow of the Keumgang Estuary Resorvoir. Here, two approach methods are proposed which can take care of the natural and the low flow. The results are as follows. The natural flow at the Keumgang Estuary Reservoir during the wet season was decreased to 8.4% and increased from 0.4% to 17.6% during the dry season by the effects of Deachung Reservoir at the upper basin. The monthly fluctuation of the low flow during My-June varies to a great extent, when large amounts of irrigation water are required.

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.20-30
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• 2014

To develop a unconventional gas reservoir, an analysis of tight rock property are required. Especially, conventional measurements are difficult to be applied to unconventional resources such as tight gas reservoir because the permeability are extremely low compared to a conventional gas reservoir. In this study, an apparatus was developed for measuring low permeability and porosity based on a pressure pulse decay method under unsteady state conditions. The apparatus was applied for measuring the porosity and permeability of tight sand core samples from Gyeongsang basin in Korea. As a validation of the measurement, regression analysis was carried out using the dimensionless pseudo-pressure between the measured data and analytical solution. The results show the correlation coefficients above 0.96. Therefore, it is believed that the apparatus has a high accuracy.

• Korean Journal of Agricultural Science
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• v.38 no.3
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• pp.513-524
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• 2011

To evaluate the applicability of inflow runoff model to reservoir operation in Korea, DAWAST model and TPHM model which are conceptual lumped daily runoff model and were developed in Korea, were selected and applied to simulate inflows to Daecheong multipurpose dam with watershed area of 4,134 $km^2$, and water storages in Geryong reservoir with watershed area of 15.1 $km^2$ and total water storage of 3.4 M $m^3$. Evaluating inflows on an yearly, monthly, ten-day, and daily basis, inflows by DAWAST model showed balanced scatters around equal value line. But inflow by TPHM model showed high in high flows. Annual mean water balance by DAWAST model was rainfall of 1,159.9 mm, evapotranspiration of 622.1 mm, and inflow of 644.6 mm, from which rainfall was 104.8 mm less than sum of evapotranspiration and inflow, and showed unbalanced result. Water balance by TPHM model showed satisfactory result. Reservoir water storages were shown to simulate on a considerable level from applying DAWAST and TPHM models to simulate inflows to Geryong reservoir. But it was concluded to be needed to improve DAWAST and TPHM model together from imbalance of water balance and low estimation in high flow.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.113-119
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• 2014

This study aims to evaluate the behavior of poorly-compacted raised reservoir levee with water level raising by using centrifugal model test. From the test results, it seems that the hydraulic fracturing at the core of the raised reservoir levee with low degree of compaction possibly occurs due to the drastical increase of pore water pressure by water level raising. Additionally, the continuous infiltration may induce crack and/or sinkhole on the surface of the poorly-compacted raised reservoir levee owing to the increase of the subsidences at the crown and the front side of that. Therefore, reasonable construction management for the compaction of the raised reservoir levee is needed.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.113-122
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• 2015

This study aims to evaluate future stream flow by the operation of agricultural reservoir group at the upper stream of the Miho River. Four agricultural reservoirs with storage capacities greater than one million cubic meters within the watershed were selected, and the RCP 8.5 climate change scenario was applied to simulate reservoir water storage and stream flow assuming that there are no changes in greenhouse gas reduction. Reservoir operation scenarios were classified into four types depending on the supply of instream flow, and the water supply reliability of each reservoir in terms of water supply under different reservoir operation scenarios was analyzed. In addition, flow duration at the watershed outlet was evaluated. The results showed that the overall run-off ratio of the upper stream watershed of the Miho River will decrease in the future. The future water supply reliability of the reservoirs decreased even when they did not supply instream flow during their operation. It would also be difficult to supply instream flow during non-irrigation periods or throughout the year (January-December); however, operating the reservoir based on the operating rule curve should improve the water supply reliability. In particular, when instream flow was not supplied, high flow increased, and when it was supplied, abundant flow, ordinary flow, and low flow increased. Drought flow increased when instream flow was supplied throughout the year. Therefore, the operation of the agricultural reservoirs in accordance with the operating rule curve is expected to increase stream flow by controlling the water supply to cope with climate change.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.43-52
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• 2006

Numerical model tests are done in order to evaluate impact zone of low salinity water on outer region of the developing Saemankeum reservoir. Also saline mixing processes are investigated f3r the inner reservoir with consideration of Mankyoung and Donjin riverine flood discharges when sea water is passing freely through gate. In these analyses 2-d ADCIRC, 3-d TIDED3D and CE-QUAL-ICM models are used. Through models tests, it is found that inner reservoir mixing process caused by inflow of outer sea water occurs gradually. It takes at least one month for complete mixing on Mankyoung part and 6 month on Dongjin part of the reservoir. When Sinsi or Garyeok gates are opened to control inner reservoir level, discharging velocities decrease exponentially from the gates, but show very strong currents of 0.5m/sec to the 10Km region apart. These results imply that hydrodynamic circulation and ecosystem of frontal region of the Saemankeum dike might be affected in amount by gate operations, since low saline inner waters are discharged periodically at ebb tide according to tidal level.

• Proceedings of the Korea Water Resources Association Conference
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• 1992.07a
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• pp.411-418
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• 1992

The purpose of this study is to develop dynamic-stochastic models that can forecast the inflow into reservoir during low/drought periods and flood periods. For the formulation of the models, the discrete transfer function is utilized to construct the deterministic characteristics, and the ARIMA model is utilized to construct the stochastic characteristics of residuals. The stochastic variations and structures of time series on hydrological data are examined by employing the auto/cross covariance function and auto/cross correlation function. Also, general modeling processes and forecasting method are used the model building methods of Box and Jenkins. For the verifications and applications of the developed models, the Chungju multi-purpose reservoir which is located in the South Han river systems is selected. Input data required are the current and past reservoir inflow and Yungchun water levels. In order to transform the water level at Yungchon into streamflows, the water level-streamflows rating curves at low/drought periods and flood periods are estimated. The models are calibrated with the flood periods of 1988 and 1989 and hourly data for 1990 flood are analyzed. Also, for the low/drought periods, daily data of 1988 and 1989 are calibrated, and daily data for 1989 are analyzed.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.3
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• pp.108-117
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• 2004

Soil particles from rainfall flow into reservoir and give lots of influence in water quality because the geological conditions and landcover characteristics of Imdong watershed have a weakness against soil loss. Especially, reservoir slant is indicated by the main source area of soil loss. This study selected RUSLE model that could apply GIS and satellite image to evaluate the contribution rate of soil loss in reservoir slant. And we carried out an on-the-spot survey for the range, width and condition of reservoir slant that give much influences to the accuracy of soil loss. As the result of evaluation to the influence of soil loss in reservoir slant, it showed 2.64% in comparison with Imdong watershed. In view of these results, the influence of soil loss in reservoir slant was evaluated in low comparing with Imdong watershed relatively.

• Journal of Korea Water Resources Association
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• v.30 no.2
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• pp.107-118
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• 1997

The Upper Fenhe Reservoir System studied by KOWACO to supply water to Taiyuan City, capital of Shanxi Province in China, is a very complicated one. Many reservoirs will be connected serially and it will be operated as a multi-purpose and multi-criteria system because several objectives and appraisal functions are taken into account regarding system operation. For reservoirs in the system, the critical system operation objectives are to minimize water shortage and reservoir sediment. Furthermore the reservoir system will be jointed with a large-scale pumping system, namely Yellow River Diversion Project. The water development cost in the Yellow River Diversion Project is much higher than that of reservoir system, and around the year 2020 the diversion volume will be twice of the surface water available in the Upper Fenhe Basin. In this study, an optimization technique for connecting the system of reservoirs and pumping station was developed to solve a conjunctive low River Diversion Project. The developed scheme includes a suggestion on the combining methodology of real reservoir system and pumping system using imaginary reservoir concept for the Yellow River Diversion Project, and practical examples to the minimization problem of the Yellow River diversion satisfying other reservoir operation objectives.