• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.700-701
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• 2005

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.99-109
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• 1997

To estimate the nutrients delivery characteristics of Chogang stream to Keum River, sediment and soil characteristics were analyzed in the stream and in the stream bank. Along the stream, soil samples from river sediment were collected and tested monthly for phosphorus and nitrogen concentrations. Nitrogen concentration in the sediment is much lower than that of soil in the river bank especially in summer presumably due to the high desorption characteristics of nitrogen by the increasing rainfall energy during summer. Instead, the concentrations of phosphorus were similar for the sediment and the soil in the river bank due to the strong adsorption characteristics of phosphorus. Batch tests were performed to evaluate the desorption potential of the sediments. Universal Soil Loss Equation (USLE) was applied to quantify soil erosion in each watershed due to rainfall. It was estimated that approximately 25% of total phosphorus by mass basis could be released from the sediment if the water was disturbed vigorously. The mass load of nitrogen and phosphorus into the Chogang Stream from the watershed were evaluated from the USLE and release ratio of phosphorus.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.35-35
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• 2023

The main reason for its instability is sediment scouring downstream of hydraulic structures. Both physical and numerical models have been used to investigate the influence of soil properties on scour hole geometry. Nevertheless, no research has been conducted on resistance parameters that affect sedimentation and erosion. In addition, auxiliary structures like wing walls, which are prevalent in many real-world applications, have rarely been studied for their impact on morphology. The hydraulic characteristics of steady flow through a boxed culvert are calibrated using a 3D Computational Fluid Dynamics model compared with experimental data in this study, which shows a good agreement between water depth, velocity, and pressure profiles. Test cases showed that 0.015 m grid cells had the lowest NRMSE and MAE values. It is also possible to quantify sediment scour numerically by testing roughness/d₅₀ ratios (c_s) and diversion walls at a meander flume outlet. According to the findings, c_s = 2.5 indicates a close agreement between numerical and analytical results of maximum scour depth after the culvert; four types of wing walls influence geometrical deformation of the meander flume outlet, resulting in erosion at the concave bank and deposition at the convex bank; two short headwalls are the most appropriate solution for accounting for small changes in morphology. A numerical model can be used to estimate sediment scour at the meander exit channel of hydraulic structures based on the roughness parameter of soil material and headwall type.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.619-628
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• 2008

Bank protection is a structure constructed to protect directly embankment breakage and erosion by river flow. Traditionally, the type of bank protection has been decided by practitioner's subjective and empirical judgement, which often causes problems after construction. Recently, however, it becomes important to consider not only physical protection but also environment. Various types of bank protection for environment-friendly river are now available. Thus, there is a need for more objective and quantitative decision method for bank protection work. This study adopts the analytic hierarchy process (AHP) to improve the objectiveness in the decision of bank protection work. Criteria for stability, economy, construction, environment are identified and a standardized process is presented for field application. With the proposed method, one can prioritize various bank protection works and make the optimal decision. We believe that the method can serve as a useful tool for river engineers in practice.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.117-124
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• 2010

Most of the rivers which exist in nature are not a single river but the network that is composed of several branches and mainstreams. The river network are more complicated than other sigle rivers and streams. Therefore the hydraulic characteristics are sensitively changed by reduction and expansion of the width in the confluence or the variation of the flux. In this paper, the hydraulic characteristics were calculated by the change of the width and length in the confluence and the hydraulic model test. The deposit of confluence emerged at the left bank, right bank and the stagnation sector. As the total flow in the branch have increased, stagnation of the left bank and right bank have decreased. When the width of the downstream have been get smaller from 3 m to 2 m, the deposit of the left bank and right bank and stagnation sector have decreased. But as the eddy flow in the center of the confluence is occurred, the erosion has been increased. The result of this paper can be used as a basic data of water management around the junction and for maintenance on the ground of development of the river.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.2 s.40
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• pp.25-31
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• 2007

The recent frequent heavy rainfall has caused an increased in soil erosion and the soil drain which drained soil has caused decreased in channel radius and environmental problems by turbidity. In this study, the optimum size of the sediment basin was tested with soil erosion estimated from the Universal Soil Loss Equation (USLE) in the basin using by GIS data. The results show that the estimated soil erosion and the designed soil deposit are $72.1\;m^3$ and $85.0\;m^3$ respectively and the size of sediment basin is proper. In this study the water depth was calculated from the Hec-Ras model to test the stability of the bank and to prove submersion of the inside fields from stream overflow.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.27-32
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• 2008

Detailed bathymetry and magnetic survey data for Esmeralda Bank obtained by R/V Onnuri of Korea Ocean Research & Development Institute in September 2007 were analyzed to estimate the locations of possible hydrothermal vents. The shape of Esmeralda Bank is caldera type opened in the western part. The summit is very shallow, about 50 meter b.s.l. and the bottom is about 1300 meter b.s.l. The western part of Esmeralda Bank is more steeper and topographic irregular than eastern part, and showed the valley made by erosion or collapse. The magnetic anomaly patterns of Esmeralda Bank located low anomalies over the north and high anomalies over the south. The magnetic anomalies are steep over the summits and gently smooth over the deep bottom. Two low magnetization zones are located in the summit and westside of Esmeralda Bank. The low magnetization zones of the summits of Esmeralda Bank suggest the possible existence of hydrothermal vent.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.22-40
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• 2009

Detailed bathymetry and magnetic survey data for NW Rota-1 and Esmeralda Bank obtained by R/V Onnuri of Korea Ocean Research & Development Institute in September 2007 were analyzed to investigate bathymetry and magnetic characteristics of the study area and to estimate the locations of possible hydrothermal vents. The shape of NW Rota-1 is corn type, and the depth of the summit is about 500 meter b.s.l. NW Rota-1 shows irregular topographic expression in the southeastern part. The shape of Esmeralda Bank is caldera type opened in the western part. The summit is very shallow, about 50 meter b.s.l. The western part of Esmeralda Bank is more steeper and topographic irregular than the eastern part, and have the valley made by erosion or collapse. The magnetic anomaly patterns of NW Rota-1 and Esmeralda Bank show low anomalies over the north and high anomalies over the south. The magnetic anomalies are steep over the summits and gently smooth over the deep bottom. The low magnetization zone occurs over the summit of NW Rota-1 and is surrounded by the high zones correlated with its crater. Two low magnetization zones are located in the summit and westside of Esmeralda Bank. The low magnetization zones of the summits of NW Rota-1 and Esmeralda Bank suggest the possible existence of hydrothermal vent.

• Journal of Korea Water Resources Association
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• v.55 no.10
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• pp.801-810
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• 2022

This study investigates the evolution processes of alternate bars in the channel with bank stability by vegetation by laboratory experiment. Laboratory experiments are conducted to elucidate the behavior of alternate bars by the influence of riparian vegetation on the rivers with erodible banks. To control bank stability of the channel, the actual vegetation, alfalfa, is grown by adjusting the density of alfalfa on the flood plain. As the vegetation density increases in the flood plain, the bank erosion rates and the channel widening rates decrease and the bank stability increases. The alternate bars migrate slow downstream over time. Moreover, the bars in a channel with strong banks migrate rapidly, which is related with the aspect ratio, that is, width to depth ratio. The bar wavelength decrease with vegetation density. Our laboratory experiments show that the behavior of bars differ according to bank strength.

• Journal of Navigation and Port Research
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• v.35 no.7
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• pp.557-562
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• 2011

Shipwaves can have harmful effects on people who are using riverside and cause bank erosion, bank structures destruction in restricted waterways. The wave field near a vessel is consisted of a combination of a primary and secondary wave system in a shallow or restricted waterway. The water level depression(squat) and return current beside the hull are called the primary wave system. The secondary wave system, that is the wave height originates from a local disturbance point such as the bow of the ship. This study aims at investigating the characteristics of the wave field around a vessel in a restricted water in relation to navigation experimentally and theoretically. The return current and squat with a correction factor can be newly evaluated and the almost same high-sized wave heights take place on the whole waterway in a restricted water without regard to the distance from the sailing line.