• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.1
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• pp.27-35
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• 2021

KRC (Korea Rural Community Corporation) is in charge of about 3,400 agricultural reservoirs out of 17,240 agricultural reservoirs, and automatic water level gauges in reservoirs and canals were installed to collect reservoir and canal water level data from 2010. In this study, 10-minute water level data of 173 reservoir irrigation canals from 2016 to 2018 are collected, and discharge during irrigation season was calculated using rating curves. For estimation of water supply, irrigation water requirement was calculated with HOMWRS (Hydrological Operation Model for Water Resources System), and the summation of reservoir water storage decrease was calculated with daily reservoir storage data from RAWRIS (Rural Agricultural Water Resource Information System). From the results, the total yearly amount of irrigation water supply showed less than 10% difference than the irrigation water requirement. The regional analysis revealed that reservoirs in Jeollanam-do and Chungcheongnam-do supply greater irrigation water than average. On the contrary, reservoirs in Gyeongsangnam-do and Chungcheongbuk-do supply less than others. This study was conducted with a limited number of reservoirs compared to total agricultural reservoirs. Nevertheless, it can indicate irrigation water supply from agricultural reservoirs to provide information about agricultural water use for irrigation.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.279-280
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• 2007

수위계 표준시험장치 초기 구축시 수직 20 m를 오르내리는 리프트에 있어서 수직 상승시 리프트가 상시 수평을 유지하는 기능이 없었기 때문에 보정값이 커지는 요인으로 작용하였다. 따라서 장치의 개선을 통하여 수평을 유지할수 있도록 스테핑모터를 이용하여 시스템을 보완하였으며, 기존의 수평제어를 하지 않았던 데이터와 스테핑모터를 이용하여 제어된 데이터를 비교하여 상호간의 성능 분석 및 수평 데이터가 보정값에 미치는 영향을 분석하고자 한다.

• Journal of Environmental Science International
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• v.27 no.6
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• pp.371-381
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• 2018

Multifunctional weirs constructed through the Four Major Rivers Restoration Project are operated as management water levels. The purpose of this study was to evaluate the effect of water level in the main stem on the tributary water level according to multifunctional weir operation, because the operation of multifunctional weirs for water level management influences the drainage of tributaries. In this study, water level pressure gauges were installed and spatial and temporal water quality was observed. The LOcally Weighted Scatterplot Smoothing (LOWESS) technique was applied to the Nakdong River and the Baekcheon Junction, both upstream of the Gangjeong-Goryeong weir, in order to analyze water quality trends. When considering the overall analysis and observations, it was found that the water quality forecasting point located at the Baekcheon estuary point should be transferred to the Dosung Bridge, which is located upstream of the Sunwon Bridge.

• Journal of the Korean Geotechnical Society
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• v.39 no.9
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• pp.51-61
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• 2023

The study aims to select an indicator that can monitor the piping stability of the foundation of a weir structure and suggest a piping stability monitoring method using the selected indicator. Based on the results from previous studies and the results of numerical seepage analysis, the change in pore water pressure in the foundation ground of the weir was selected as an indicator for piping monitoring. Considering the state in which the pore water pressure gauges are installed in operating weirs, seepage analyses were performed according to various upstream water level conditions for each case where one or two gauges were installed at the bottom of the weir. A piping monitoring method was presented based on the analysis results for each of these cases. In addition, the proposed monitoring method was shown to be effective by providing an example of a trial application to an operating weir.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.5
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• pp.651-659
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• 2018

A multi-level overtopping wave energy converter was designed according to the large tidal range and small wave heights in China. It consists of two reservoirs with sloping walls at different levels. The reservoirs share a common outflow duct and a low-head axial turbine. The experimental study was carried out in a laboratory wave-flume to investigate the overtopping performance of the device. The depth-gauges were used to measure the variation of the water level in the reservoirs. The data was processed to derive the time-averaged overtopping discharges. It was found that the lower reservoir can store wave waters at the low water level and break the waves which try to climb up to the upper reservoir. The upper sloping angle and the opening width of the lower reservoir both have significant effects on the overtopping discharges, which can provide more information to the design and optimization of this type of device.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.4
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• pp.331-337
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• 1995

This study was carried out to investigate the chemical composition of dustfall at Cheju(mean sea level; 71.7m, 33$^{\circ}$17'N, 126$^{\circ}$10'E) and Ullung island(mean sea level; 22.1m, 38$^{\circ}$29'N, 130$^{\circ}$54'E) from October 1993 to september 1994. The dustfall matter samples were collected by deposit gauges. The ionic components of each samples was analyzed by Ion Chromatograpy (Dionex 4000i), While heavy metals by Inductively Coupled Plasma Atomic Emission Spectrometry(ICP/AES; Shimadzu ICP-4). The results for seasonal variation of dustfall matter matter total amount, water-soluble ionic components and water-soluble ionic components total deposition amount to two sites were compared each other. The seasonal variations of dustfall amount at Ullung and Cheju island were found in order of Spring>Winter>Fall>Summer, and the maximum of dustfall amount were during the Yellow Sand period. Also, Total amount of water-soluble components except for $F^{[-10]}$ were high in Cheju more than Ullung island.more than Ullung island.

• Journal of Korea Water Resources Association
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• v.42 no.6
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• pp.493-503
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• 2009

Estimation of the mean-field bias of radar rainfall is to determine the difference between the areal means of radar and rain gauge rainfall, where the rain gauge rainfall is assumed to be the truth. To exactly determine this bias, the variance of the difference between two observations must be small enough, thus, enough number of observations is indispensible. So, the problem becomes to determine the number of rain gauges to satisfy the level of variance of the difference between two observations. Especially, this study focuses on the case when the rain gauges are disproportionate spatially. This is the problem for the Ganghwa rain radar for the observation of rainfall within the Imjin river basin and the same problem also occurs when a radar is located in between land and ocean. This study considered the Imjin river basin, and compared two cases when rain gauges are available only within the downstream part, about one third of the whole basin, and over the whole basin. Based on the results derived, the rain gauge density within the downstream part of the Imjin river basin was proposed to secure the same accuracy obtained when the rain gauges are available over the whole Imjin river basin.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.134-134
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• 2022

Streamflow forecasting plays a crucial role in water resource control, especially in highly urbanized areas that are very vulnerable to flooding during heavy rainfall event. In addition to providing the accurate prediction, the evaluation of effects and importance of the input predictors can contribute to water manager. Recently, machine learning techniques have applied their advantages for modeling complex and nonlinear hydrological processes. However, the techniques have not considered properly the importance and uncertainty of the predictor variables. To address these concerns, we applied the GA-BART, that integrates a genetic algorithm (GA) with the Bayesian additive regression tree (BART) model for hourly streamflow forecasting and analyzing input predictors. The Jungrang urban basin was selected as a case study and a database was established based on 39 heavy rainfall events during 2003 and 2020 from the rain gauges and monitoring stations. For the goal of this study, we used a combination of inputs that included the areal rainfall of the subbasins at current time step and previous time steps and water level and streamflow of the stations at time step for multistep-ahead streamflow predictions. An analysis of multiple datasets including different input predictors was performed to define the optimal set for streamflow forecasting. In addition, the GA-BART model could reasonably determine the relative importance of the input variables. The assessment might help water resource managers improve the accuracy of forecasts and early flood warnings in the basin.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.35-43
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• 2003

Methods for measuring wave height and direction varies throughout the world, depending on wave climate and local traditions. In Japan, bottom mounted systems have long been the standard fur coastal areas with water depth less than 50m, and extensive studies in the 1980s and 1990s refined the systems to a level where the full wave directional spectrum could be measured. (omitted)

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1708-1710
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• 2007

댐 및 저수지 운영에 필수 요소인 수위 데이터의 신뢰성을 높일 수 있도록 수위측정에 가장 많이 사용되고 있는 부자식, 초음파식, 레이다식 수위계의 특성시험이 가능한 표준시험장치와 표준시험장치에 대한 운영의 일관성을 확보하기 위한 표준시험절차를 개발하였다. 또한, 표준시험장치의 최고측정능력을 산출하여 수위계 시험에 따른 불확도를 산출할 수 있도록 수위 측정 모델식을 제시하여 합성불확도1.408 mm와 확장불확도 3 mm를 각각 얻었다. 본 연구에서 제시된 최고측정능력은 수위데이터의 신뢰성 있는 자료 확보와 일관성 있는 자료관리가 가능하도록 품질관리 기반을 구축하였다.