• Journal of Environmental Science International
• /
• v.9 no.1
• /
• pp.35-42
• /
• 2000

In this study, the movable bed model testing was carried out so as to analyze bed profile changes including predicting scouring and deposition of bed profile and to solve hydraulic problems affecting with bed and both-bank between upstream and downstream of intake weir in the Nakdong river channel. The movable bed model testing consists of fundamental test, movable model test and numerical analysis method respectively. The fundamental test was enforced to analyze relationship of discharge and sediment load in the tilting flume. When the movable model test was worked, it was shown that sediment budget between input sediment load and output sediment load was balanced exactly. As a result of movable model test, it was presented that scouring and deposition changes in quantities between the upstream and downstream of modification weir were less than those of nature and planning weir. Finally, numerical analysis method was operated by 1-dimensional bed profile changes model ; HEC-6 model so as to complement unsolving hard problems during movable model test. So, modification weir will sustained the stable bed profile changes than any other weirs in the study channel.

• Earthquakes and Structures
• /
• v.13 no.4
• /
• pp.421-427
• /
• 2017

Seismic safety evaluation of weir structure is significant considering the catastrophic economical consequence of operational disruption. In recent years, the seismic probabilistic risk assessment (SPRA) has been issued as a key area of research for the hydraulic system to mitigate and manage the risk. The aim of this paper is to assess the seismic probabilistic risk of weir structures employing the seismic hazard and the structural fragility in Korea. At the first stage, probabilistic seismic hazard analysis (PSHA) approach is performed to extract the hazard curve at the weir site using the seismic and geological data. Thereafter, the seismic fragility that defines the probability of structural collapse is evaluated by using the incremental dynamic analysis (IDA) method in accordance with the four different design limit states as failure identification criteria. Consequently, by combining the seismic hazard and fragility results, the seismic risk curves are developed that contain helpful information for risk management of hydraulic structures. The tensile stress of the mass concrete is found to be more vulnerable than other design criteria. The hazard deaggregation illustrates that moderate size and far source earthquakes are the most likely scenario for the site. In addition, the annual loss curves for two different hazard source models corresponding to design limit states are extracted.

• Journal of Korean Society on Water Environment
• /
• v.38 no.1
• /
• pp.1-9
• /
• 2022

The Yeongsan River, one of the four major rivers in Korea, shows the highest degree of water pollution compared to the other major rivers. The construction and opening of two weirs, Seungchon and Juksan, induced fluctuations in the hydrologic conditions and water quality of the river. To investigate the water quality changes caused by the opening of the weir in 2017, this study analyzed the water quality data using the non-parametric Wilcoxon signed-rank test and the three-dimensional spatiotemporal plots. The non-parametric statistical test results showed that the concentration of all parameters has increased after 2017 at a significance level of 0.05. For the parameters that showed the highest degree of change, chlorophyll-a and suspended solids, the median values have increased by more than 30% after weir opening. Visual analysis additionally showed the spatial changes in the Yeongsan River. Generally, the sites above the Seungchon weir showed higher pollution levels than those above the Juksan weir. In time series, visual analysis results also showed the trend of rising concentration for all water quality parameters, indicating that the opening of two weirs had a significant effect on the change in water quality of the Yeongsan River.

• Journal of The Geomorphological Association of Korea
• /
• v.28 no.4
• /
• pp.1-13
• /
• 2021

In this study is aerial photos and UAV(Unmanned Aerial Vehicle) images were used to analyzed the characteristics of depositional landform changes in the Geum river channels before and after the opening gate of Gongju weir. Based on the depositional landform classification result, the main stream and the bare land occupied most of the area in all periods, and also found that the main stream, mid-channel island, and sand bar occupied a greater degree of area increase or decrease compared to other landforms in the classification items. As a result of analyzing the characteristics of depositional landform changes before and after the opening gate of Gongju weir, it is judged that the depositional landforms have changed due to the decreased water level of the Geum river after the opening of the weir, the summer rainy season and typhoons, river stabilization after the effluence of Daecheong dam, supply and deposition of river sediments and fixation of vegetation. The results derived from this study can be used as basic data for the study of river depositional landforms and the establishment of management and conservation plans for the landforms in river channels.

• Water for future
• /
• v.29 no.2
• /
• pp.153-165
• /
• 1996

One-dimensional unsteady flow model including weir flow simulation is studied. Applicabilities of both the single channel model with local treatment of the weir overflow, and the looped-network model are studied using a test problem. It is shown that various type of weir flows including reverse flows are successfully simulated. Flow discontinuity due to the high crest elevation can also be simulated. The reverse free-flowing overflow can be simulated by the single-channel model as well as by the looped-network model.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.09a
• /
• pp.121-122
• /
• 2005

• Journal of Environmental Science International
• /
• v.25 no.4
• /
• pp.491-504
• /
• 2016

This study, examines the flow characteristics of upstream channel depending on water gate operation of Nakdan Multi-fuctional weir. The specific purpose of this study are to simulate the variation of flow velocity depending on the operation of the weir using 1-dimensional hydraulic model, HEC-RAS, and compare it with observed velocity. For discharge conditions from $50m^3/s$ to $3,500m^3/s$, it is observed that the velocity of upstream channel is almost constant, whereas for probability flood discharge, the velocity and froude number are increased as the discharge values are increased. The velocity values for downstream boundary condition EL, 40.0 m are more decreased than those for EL. 40.5m. From comparison on the variation of water stage depending on water gate operation, it is observed that the stage values are almost constant for discharges below $300m^3/s$, whereas 5 cm to 20 cm for discharges over $700m^3/s$. Flow velocity at streamflow gauging station. Nakdong, is decreased by more than 875% after installing the weir. The results obtained from this study indicate that the velocity of upstream channel is decreased and the discharge and velocity of downstream channel are significantly varied after installing the weir.

• Ecology and Resilient Infrastructure
• /
• v.3 no.4
• /
• pp.294-301
• /
• 2016

The underflow type movable weirs were arranged in a multi-stage way at a section of the Chiseong River, a tributary of Geum River, where flooding is observed frequently. The flood control and the movable weir management levels were compared with the occasions of installing the existing weir for analysis. The peak discharge decreased by a maximum of 97% for the underflow type movable weir, and the downstream flood elevation decreased by a maximum of 82%. The amount of storage also increased by a maximum of 463% by the distribution and storage functions of the multi-stage arrangement of the underflow type movable weirs. It is possible to suggest that the management level of each movable weir for the target storage of the reach and the flood reduction level through the relationship among this storage, downstream peak flood elevation, and peak flow.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.5
• /
• pp.73-81
• /
• 2017

The improved movable weir supplements the advantages and disadvantages of the rubber weir and the conduction gate. It consists of a stainless steel gate, air bags, and a steel clamping plate. The stainless steel gate is the main body of the weir, and the inflatable rubber sheet serves to support the steel gate. The steel clamping plate is typically in direct continuous contact with water, but this leads to corrosion issues that can reduce the life of the entire movable weir. In this study, a panel-type glass-fiber-reinforced polymer (GFRP) clamping plate was designed and fabricated. The test results showed that the flexural load of the panel-type GFRP composite clamping plate was over twice that of the wings type GFRP clamping plate. The lowest moisture absorption value was obtained upon exposure to tap water, and exposure to other solutions showed similar values. Additionally, flexural load testing after exposure to an accelerated environment found the lowest residual loads of 80.51 % and 78.50 % at 50 and 100 days, respectively, for exposure to a $CaCl_2$ solution, while exposure to other environments showed residual failure loads of over 80 % at both 50 and 100 days.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.24 no.1
• /
• pp.23-30
• /
• 1982

The aim of this report is to analyze the Occurring rate of damage at each region of head works and to clear its damaged mechanism, centering around the destroyed situations of head works along both Musim and Bochong Rivers suffered from the storm flood occurred on July 22, 1980. The results obtained from the investigation of 25 head works taken for samples are summarized as follows. 1. The occurring rate of damage at each region of head works showed the largest number of 100 percentage in the revetment and protected riverbed work respectively, in the order of the next largest number, 68 percentage in weir body, 56 percentage in apron and 36 percentage in bank. 2. The destructive damage of revetment influenced largely on sweeping bank away, and destructive sufferings of weir body and protected bed work affected on the destructi on of apron, otherwise the destructive sufferings of apron reversely also acted on the- destruction of weirbody and protected bed work. In other hand, partial damage of weir body at the side of revetment is largely influenced by destructive sweeping away of bank. 3. It was showed that the destructive phenomena of weir body occurred largely at the part of concentrated flow and also had a deep relation with scoring by concentrated flow around upstream foundation of weir. 4. The suffered region of revetment is the down stream part just near weir body and the degree of damage is more severe at the curved part of bank that center of flow is concentrated.