Choi S.-U.,Yonsei University |
Joung Y.,ISAN Corporation
Journal of Hydro-Environment Research | Year: 2012
This paper presents a numerical model that is capable of simulating the morphological process of the trapezoidal open-channel. The fact that particles on the sloped side bank do not move in the same direction as the flow adds the difficulty in modeling. The lateral distribution model, which distributes the unit discharge over the width, is used for the flow analysis. Vectorial bedload formula by . Kovacs and Parker (1994) is used and channel topography is calculated by solving Exner's equation with the help of sliding algorithm proposed by . Menendez et al. (2008). Values of roughness coefficient and lateral eddy viscosity are calibrated using laboratory data sets. Finally, the proposed model is applied to laboratory experiments of . Ikeda (1981) and . Izumi et al. (1991). Time evolutions of channel cross section and dimensionless shear stress are provided and discussed. © 2012 International Association for Hydro-environment Engineering and Research, Asia Pacific Division.
Seo D.,Chungnam National University |
Sigdel R.,Chungnam National University |
Kwon K.H.,Isan Corporation |
Lee Y.S.,Korea Engineering Consultants Corporation
Desalination and Water Treatment | Year: 2010
The successful water quality prediction requires accurate information of water movement and interaction kinetics of components in water. Recent researches showed significant advancement in the combined use of hydrodynamic model and water quality model for surface water quality predictions. USEPA upgraded this progress to 3-dimensional (3-D) level through modification of Environmental Fluid Dynamics Code (EFDC) hydrodynamic model to provide water movement information to Water Quality Analysis Simulation Program (WASP) water quality model for multiple components. However, a 3-D model requires heavy computation time and extensive data for calibration, therefore, optimum layout of computational grids is a most important factor for application. This study summarizes performance of EFDC in the prediction of water level thus water volume change dynamics and vertical water temperature profile variations. This model was applied to Yongdam Lake, Korea and successfully modeled water level and vertical temperature profile of the study site. The resultant 3-D hydrodynamic information can be transferred to 3-D water quality model, WASP and can be used for water quality management purposes. © 2010 Desalination Publications. All rights reserved.
Schultz B.,UNESCO IHE |
Hayde L.,UNESCO IHE |
Sang-Hyun P.,ISAN Corporation |
Tanaka K.,Tanaka R and D Gijutsu Jimusho
Irrigation and Drainage | Year: 2013
Closed-off tidal basin reclamation represents a special type of reclamation. In several countries enclosing dams have been built to close off estuaries, shallow seas, or lagoons, and lands up to 5~6m - MSL (below mean sea level) have been reclaimed in the former tidal basins. Although these areas were generally primarily reclaimed for agriculture, a second-stage development may have taken place where parts of these lands were transferred to urban and industrial use. The originally saline water in the created reservoirs was transformed to fresh water that may be used for irrigation, domestic and/or industrial water supply. In several of these reservoirs there are water quality problems, primarily due to pollution in upstream parts of the river basins. In 2007 the Enclosing Dam of the Zuiderzee Scheme in the Netherlands had existed for 75years. This occasion was used to conduct a global inventory of closed-off tidal basin reclamation on which this paper is based. The study shows that closed-off tidal basin reclamation concerns 25 schemes with a total area of 738 000ha, of which 337 000ha have been reclaimed and 401 000ha freshwater reservoirs have been created. This paper presents a summarized overview. Attention is paid to safety, land use and changes in it, development of water quality in the reservoirs, as well as to land subsidence and possible impacts of climate change, like rise in mean sea level. In time this may have implications for safety of the deep polders, the management of the reservoirs as well as for the sustainable development of tidal areas in the future. These items are presented for four major tidal reclamation schemes: the Zuiderzee Scheme in the Netherlands, the Saemangeum Scheme in South Korea, the Kuttanad Region in India and the Hachirogata Scheme in Japan. © 2013 John Wiley & Sons, Ltd.
Kim B.-J.,Gangneung - Wonju National University |
Yune C.-Y.,Gangneung - Wonju National University |
Kim K.-S.,Korea Expressway Corporation |
Lee S.-D.,ISAN Corporation
Landslides and Engineered Slopes. Experience, Theory and Practice | Year: 2016
Recently, the frequency of debris flow hazard has increased in Korea. The debris flow occurring around expressway can cause serious direct and indirect damages not only on cars and drivers on the road but also on national infrastructures. For the effective prevention of debris flow on expressway, potential basin areas with a high possibility of hazard need to be selected and a quantitative risk assessment for those basin areas should be performed. In this study, a risk assessment of debris flow on 1545sites (1093 km) of public expressway was conducted by the risk evaluation method suggested by Korea Expressway Corporation. Based on the risk assessment, basin characteristics of high and low risk areas around expressway were analyzed. Analysis results showed that the basin areas at 507 sites (33%) out of total 1,545 sites were at high risk for debris flow. And they have a higher inclination than low risk area for both average basin area and stream channel. © 2016 Associazione Geotecnica Italiana, Rome, Italy.
Joung Y.,ISAN Corporation |
Choi S.-U.,Yonsei University
International Journal for Numerical Methods in Fluids | Year: 2010
A direct numerical simulation of low Reynolds number turbulent flows in an open-channel with sidewalls is presented. Mean flow and turbulence structures are described and compared with both simulated and measured data available from the literature. The simulation results show that secondary flows are generated near the walls and free surface. In particular, at the upper corner of the channel, a small vortex called inner secondary flows is simulated. The results show that the inner secondary flows, counter-rotating to outer secondary flows away from the sidewall, increase the shear velocity near the free surface. The secondary flows observed in turbulent open-channel flows are related to the production of Reynolds shear stress. A quadrant analysis shows that sweeps and ejections are dominant in the regions where secondary flows rush in toward the wall and eject from the wall, respectively. A conditional quadrant analysis also reveals that the production of Reynolds shear stress and the secondary flow patterns are determined by the directional tendency of the dominant coherent structures. Copyright © 2009 John Wiley & Sons, Ltd.
Hyun P.S.,ISAN Corporation |
Ok K.J.,Rural Research Institute of the Korea Rural Community Corporation |
Jae J.K.,Rural Research Institute of the Korea Rural Community Corporation |
Bae L.D.,National Academy of Agricultural Science
Irrigation and Drainage | Year: 2013
This study has been carried out to evaluate the habitat role for migratory birds in a tidal reclamation area in comparison with a river estuary in Korea. It also includes the contribution effect of the contract on the optional Choice of Paddy Field Management (CPFM) program to sustain biodiversity of winter migrants in Korea. The CPFM program has been practiced to attract winter migratory birds in cooperation with the farmers who spread rice straw, cultivate barley and provide shallow flooding paddy during the winter season in various reclaimed areas. The study result shows that a large number of winter migratory birds visited the tidal reclamation areas and the reason given is that wave intrusion was prevented by the sea dike and water level changes in the lake are less than tidal level changes in the estuary, as well as the irrigated paddy field supply of food and shelter for the birds in the reclaimed area. In the tidal reclamation area, the dominant species are waterfowl such as geese and ducks, while waders, shore birds and other small birds have declined after reclamation in the area, as the freshwater lakes are rather deeper than coastal shorelines to attract them. In conclusion, tidal areas with large paddy fields and freshwater lakes have allowed not only an increase in food production but also have attracted winter migrants supported by farmers and government; however, more effort will be needed to provide habitats for rare and distinctive birds in the reclamation area. © 2013 John Wiley & Sons, Ltd.
Choi S.-U.,Yonsei University |
Lee J.,ISAN Corporation
Journal of Hydro-Environment Research | Year: 2015
A new numerical model for predicting the total sediment load in the river is presented. The model is comprised of two parts, namely flow and sediment transport parts. The flow analysis is carried out using the lateral distribution method, which distributes the flow and sediment load across the width, based on channel geometry and flow dynamics. To obtain the total sediment load, the bedload and suspended load are predicted separately. Conventional formulas are used for the bedload, and Rousean distribution with an entrainment function is used for the suspended load. Einstein partition is used to separate the form drag component from the total shear stress. The model is applied to the Danube River, a gravel-bed river in Slovakia and the Han River, a sand-bed river in Korea. Predicted distributions of sediment load in the lateral direction are given. The predicted results are compared with those obtained using the 1D approach as well as from measured data. Total sediment load rating curves are presented and the mixture effect of bed-materials is discussed. © 2014 International Association for Hydro-environment Engineering and Research, Asia Pacific Division.
Isan Inc. | Date: 2011-08-05
Metal bolts; Metal hardware, namely, washers; Metal nuts.