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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Civil Engineers
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Korean Society of Civil Engeneers
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Volume & Issues
Volume 27, Issue 6D - Nov 2007
Volume 27, Issue 6C - Nov 2007
Volume 27, Issue 6B - Nov 2007
Volume 27, Issue 6A - Nov 2007
Volume 27, Issue 5D - Sep 2007
Volume 27, Issue 5C - Sep 2007
Volume 27, Issue 5B - Sep 2007
Volume 27, Issue 5A - Sep 2007
Volume 27, Issue 4D - Jul 2007
Volume 27, Issue 4C - Jul 2007
Volume 27, Issue 4B - Jul 2007
Volume 27, Issue 4A - Jul 2007
Volume 27, Issue 3D - May 2007
Volume 27, Issue 3C - May 2007
Volume 27, Issue 3B - May 2007
Volume 27, Issue 3A - May 2007
Volume 27, Issue 2C - Mar 2007
Volume 27, Issue 2A - Mar 2007
Volume 27, Issue 2D - Mar 2007
Volume 27, Issue 2B - Mar 2007
Volume 27, Issue 1D - Jan 2007
Volume 27, Issue 1C - Jan 2007
Volume 27, Issue 1B - Jan 2007
Volume 27, Issue 1A - Jan 2007
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Parameter Estimation of NWS-PC Model Using Multi-step Automatic Calibration Scheme
Kang, Shin-Uk ; Lee, Sang-Ho ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 211~218
The simulated discharges with parameters estimated from a Single-step Automated Calibration Scheme (SACS) can have large errors on the baseflow part or bias against the measured discharge. To reduce the errors and the bias, the parameters of NWS-PC model were estimated from a Multi-step Automated Calibration Scheme (MACS). The simulated discharges with parameters estimated from MACS produced smaller errors not only on the flood season but on the non-flood season. The parameters related to the lower zone of a watershed were tuned finely by MACS to simulate baseflow well. The statistics of root mean square error and percent bias annually calculated from the results of MACS are better than those of SACS. Nash-Sutcliffe Efficiency has no difference between SACS and MACS for the whole period but MACS method is better by 5% or more for the five years among the thirty two years. MACS is also better for persistence model efficiency by 42% in 1989 and by 9% or more in 1994 and 1997. MACS can improve accuracy of watershed runoff continuous simulation model.
Development of Steady Non-Uniform Flow Model for a Transcritical River
Kim, Ji-Sung ; Han, Kun-Yeun ; Lee, Chang-Hee ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 219~228
A numerical model (RIV1D) in order to calculate the transcritical flow which describes the existence of both subcritical and supercritical flow is developed. In this study, the derivatives of natural geometry cross-section informations to use the iterative method are determined and the mixing of Newton-Raphson and Bisection method to compute the critical depths and water surface elevations enables the numerical solutions to be a good agreement with the analytical solutions or measured data. The developed model, RIV1D is applied in various transcritical conditions, gate opening, steep chute channel, channel with the bell-shaped bed, and real dam spillway and gives accurate and stable solutions. As a result, the developed model, RIV1D can be used for the field of hydraulic analysis in the open channel, including the hydraulic jump, flow condition influenced by the hydraulic structure or the riffle-pool, and initial flow condition in the unsteady analysis.
Numerical Simulation of Alluvial Fans
Jang, Chang-Lae ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 229~235
This study is to analyse the development of alluvial fans, using the 2-D numerical model to simulate complex flow and the relation between bars and channels, proposed by Jang and Shimizu in 2005. As a numerical scheme, CIP method and central difference method was used in the moving boundary-fitted coordinate system. The numerical model captured well the characteristics of alluvial fans, e.g., fan-head entrenchment and channel formation in depositional area, expansion of depositional area downstream, channel backfill by sediment inflow, increase of channel slopes, channel avulsion and migration in alluvial fans. As the sediment inflow increased upstream, the averaged elevation and area of alluvial fans were increased, the longitudinal and transverse slopes of the fans steepened, and then channel avulsion in fans was accelerated. Therefore, sediment inflow in alluvial fans upstream was the crucial factor to channel avulsion, one of important features of alluvial fans.
Development of Korea Flash Flood Guidance System: (I) Theory and System Design
Bae, Deg-Hyo ; Kim, Jin-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 237~243
The objective of this study is to develop a Korea Flash Flood Guidance (KoFFG) system over the Han River basin. FFG is composed of threshold runoff computation and soil moisture accounting for hydrological component and radar rainfall estimates for meteorological component. In this paper, the background of hydrometeorological theory was described to construct FFG components. Each component is used to design the real-time flash flood guidance system composed of pre-processing for collecting various input data and post-processing for a dissemination and an easy use of the FFG products. Also, This system was constructed with the precipitation data of radar and RDAPS(Regional Data Assimilation and Prediction System) to forecast a flash flood warning and watching, respectively.
Development of Korea Flash Flood Guidance System: (II) Component Development and System Analysis
Bae, Deg-Hyo ; Kim, Jin-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 245~254
The objective of this study is to develop a Korea Flash Flood Guidance (KoFFG) system over the Han River basin. For the purpose, threshold runoff of high resolution sub-catchment was estimated for each duration based on the delineated geometry from digital terrain elevation and the matching of surface runoff peak to bankfull flow. The model-based soil moisture status was calculated by the semi-distributed TOPMODEL. The stochastic logarithmic bias adjustment model by using Kalman filter scheme was used to minimize the large scale bias for optimal radar rainfall estimates over the region. FFG were computed by the meteorologic and hydrologic components during July of 2004, and the case studies for the possibility of future flash flood threat were performed with the forecasted precipitation of RDAPS (5 km) model. The real-time KoFFG system was designed and developed with pre-processing, core computation module, and post-processing. The case studies were performed with historical data for the flash flood occurrence. It is shown that the developed KoFFG system is useful to forecast a warning of flash flood by using radar data and the accuracy of RDAPS would be needed to increase for the forecast of future flash flood threat.
Combining Radar and Rain Gauge Rainfall Estimates for Flood Forecasting Using Conditional Merging Method
Kim, Byung-Sik ; Hong, Jun-Bum ; Kim, Hung-Soo ; Choi, Kyu-Hyun ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 255~265
In this paper describes a short overview over the gauge adjustment methods applied in operational fields. and the technique employed is a conditional merging technique (CM). To evaluate the this method, statistics and hyetograph for rain gauges and radar rainfalls are compared using hourly radar rainfall data from the Imjin-river, Gangwha, rainfall radar. Results show that rainfall field estimated by Condional Merging method give the best results in a statistics and qualitative way.
Construction of Hydrological Drought Severity-Area-Duration Curves Using Cluster Analysis
Kyoung, Min-Soo ; Kim, Sang-Dan ; Kim, Bo-Kyung ; Kim, Hung-Soo ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 267~276
In this study, cluster analysis is applied to classify the whole of South Korea into several groups for characterizing spatially drought events. The standard precipitation index (SPI) is selected as the drought parameter. Using hierarchical cluster analysis and complete linkage method, South Korea is divided into 6 groups. The SPIs of 58 gage station's precipitation data provided in Korea Meteorological Administration are computed and their spatial informations are extracted using EOF analysis. Spatially extended EOF values through kriging theory are used to construct the severity-area-duration (SAD) curve in each group. As a whole, drought severity decreases as drought duration increases. However, it is found that the spatial reduction rate of severity by cluster-based SAD curves is less than that of non-cluster based SAD curves. The analysis of clustered SAD curves reveals that the drought severity is the deepest in the east coast of South Korea.
Estimation of Sediments in Urban Watersheds and Relation Analysis between Sediments and Inundation Risk Using GIS
Park, Moo-Jong ; Shin, Min-Chul ; Jun, Hwan-Don ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 277~287
Sediments in urban watersheds coming into sewer pipes reduce conveyance of sewer pipes and it is one of the reasons increasing inundation risk during the summer season. To establish management plans for this problem, it is required to estimate the range and the amount of sediments in urban watersheds. Before quantifying the amount of sediments, the area of individual landuse in each subbasin should be obtained. However, because of the complication in landuse of an urban watershed, it is almost impossible to obtain it by manual ways. Thus, as a new application of GIS for water resources engineering, this study suggests a methodology to obtain landuse area of each subbasin and to estimate the amount of sediments. Using GIS, an urban watershed is divided into subbasins with respect to sewer layout and then for each subbasin, the area of individual landuse including road is estimated. Based on results from applying GIS, sediments per unit area can be calculated as well as the amount of sediments for each subbasin. The suggested method is applied to the Goon Ja watershed in Seoul to verify its applicability. For analysis of the relationship between sediments and inundation risk, subbasins are ordered by the amount of sediments per unit area and compared with historical inundation areas of the watershed by using GIS. From the analysis, it is found that subbasins with higher order are matched with the historical inundation areas of the watershed. Thus, it can be concluded that sediments may increase inundation risk.
Numerical Investigations of Streamwise Vortical Structures in Fully Vegetated Open-Channel Flows
Kang, Hyeong-Sik ; Choi, Sung-Uk ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 289~299
This paper presents a numerical investigation of the streamwise vortical structures in fully vegetated open-channel flows. The Reynolds stress model is used for the turbulence closure. Open-channel flows with various aspect ratios and vegetation densities are simulated. The computed vectors show the lateral subchannels, which results in wavy isovels of streamwise mean velocity. The velocity dip phenomenon due to the bottom vortex is clearly observed near the juncture between the free surface and the sidewall. This lateral heterogeneity is pronounced as the vegetation density increases. However, when the vegetation density exceeds a critical value of a = 1.0 m-1, the lateral heterogeneity is weakened and the lateral flow structures become almost uniform. A depth-averaged analysis of the streamwise momentum equation is also performed to investigate the lateral momentum transfer. It is found that the component of secondary currents increases the bottom shear stress near the sidewall, while the component of lateral Reynolds stress decreases the bottom shear stress.
Development of Semi-implicit Three Dimensional(Si3D) Finite Difference Model and Model Calibration in the Sacramento-San Joaquin River Delta
Cheong, Tae-Sung ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 301~311
Estuaries are a valuable natural resource as habitat for living creature. An evaluation of the environmental effects of an estuarine change in which the distribution and transport of estuarine salts, sediments, contaminants, and certain biological organisms (for example, plankton and larval fish) are governed by advection and dispersion usually requires an understanding of the physical processes of water circulation and mixing. Because significant variations in currents and salinity occur in all three spatial dimensions in most estuaries, 3-D models are needed. For example, tidal currents in estuaries that flow in opposite directions at different depths or travel in one way near a shoreline and in the opposite way near the center of a channel are not uncommon. The density gradients that occur in estuaries are severe enough to affect the longitudinal and transverse circulations and the vertical mixing. A fine grid three-dimensional semi-implicit finite deference hydrodynamic(Si3D) model and the particle tracking model were developed to validate hydrodynamic mechanisms and fish behaviors in the vicinity of Delta Cross Channel. For the calibration, 3-D numerical model results for flow, water surface elevation, and velocity profile data are compared with field studies data obtained in 2000. The results show that the new model fits flow and water surface elevation data measured in the vicinity of DCC better than DSM2. The Si3D provides represents of three dimensional velocity profiles measured in the vicinity of DCC.
Numerical Simulation of the Water Column Collapse using SPH Method
Kim, Nam-Hyeong ; Ko, Haeng-Sik ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 313~318
Smoothed Particle Hydrodynamics (SPH) method is a meshless Lagrangian method using the particle, which is different from previous methods using the mesh. The Navier-Stokes equations for the incompressible viscous flow is applied. In this study, the numerical analysis of two-dimensional water column collapse by SPH method is carried out, and the result is compared with Martin and Moyce's experimental data and the result of MPS and SMAC method. And a good result is obtained. The phenomenon of water column collapse by using the particle and velocity vector is also visualized, and the sensitive analysis on the artificial viscosity a-term and particle number is performed. Finally it is shown that this method could be applied to the breaking phenomenon of hydraulic structures such as dam break.
Development and Validation of KModSim for the Decision Support System in Geum River Basin
Cheong, Tae-Sung ; Kang, Shin-Uk ; Ko, Ick-Hwan ; Hwang, Man-Ha ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 319~329
As water supplies, the hydraulic power, and environmental flows are in conflict each other, the river basin planning and management is necessary to maximize water efficiency. Especially, because water is no more enough to achieve the both target of quantity and quality, the real time decision support system based on estimation of both demands and diversion and rainfall-runoff analysis is important to aid good information for the river basin planning and management. In this study, the KModSim was developed for the decision support system and calibration, management simulation, and validation for the river basin planning and management are performed.
Asymptotic Variance of Quantile for Estimating Confidence Intervals of the Generalized Logistic Distribution : I. Derivation of the Asymptotic Variances
Shin, Hong-Joon ; Kim, Soo-Young ; Heo, Jun-Haeng ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 331~338
The error of estimate accounts for the error due to the shortness of the sample data and the choice of inappropriate distribution. Hence, it is clear that a point estimate of quantile corresponding to specified return period may be of no real significance unless there is an indication of the prediction accuracy of distribution. The generalized logistic (GL) distribution has been widely used for frequency analysis. However, there is a little study related to the confidence intervals that indicate the prediction accuracy of distribution for the GL distribution. In this paper, the estimation of parameters are introduced and the asymptotic variances of quantiles for the GL distribution are derived to estimate the confidence intervals based on the method of moments (MOM), maximum likelihood (ML), and probability weighted moments (PWM). As a result, it was found that the asymptotic variances of quantile estimator are represented as a function of the sample size, return period, and parameters for each estimation technique.
Asymptotic Variance of Quantile for Estimating Confidence Intervals of the Generalized Logistic Distribution : II. Simulation and Application
Shin, Hong-Joon ; Kim, Soo-Young ; Heo, Jun-Haeng ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 339~344
Monte Carlo simulation experiments were performed to verify the applicability of the derived asymptotic variance for estimating confidence intervals of quantile using the results from the previous study "Asymptotic Variance of Quantiles for Estimating Confidence Intervals of the Generalized Logistic Distribution : I. Derivation of the Asymptotic Variances". In this study, simulation experiments were performed to find out the applicability of the derived confidence intervals of quantiles based on the methods of moments, maximum likelihood, and probability weighted moments. For this purpose, the location and scale parameters were set to 0 and 1, respectively, and the shape parameter was varied as +0.11387, -0.06134, -0.11387 (corresponding skewness coefficients: -1.0, +0.5, +1.0, respectively). As the results, the relative bias (RBIAS) and relative root mean square error (RRMSE) of the confidence intervals generally increase as return period increases and reverse as sample size increases. And PWM for estimating the confidence intervals performs better than the other methods in terms of RRMSE when the data is almost symmetric while ML shows the smallest RBIAS and RRMSE when the data is more skewed and sample size is moderately large. The GL model was applied to fit the distribution of annual maximum rainfall data. The results show that there are little differences in the estimated quantiles between ML amd PWM while distinct differences in MOM. And ML and PWM show the smallest variances and the narrowest confidence intervals depending on sample sizes and skewness coefficients.
Asymmetry in Directional Spreading Function of Multi-Directional Random Waves due to Refraction
Lee, Chang-Hoon ; Jung, Jae-Sang ; Cho, Yong-Sik ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 345~353
In this study, the directional spreading function is suggested which considers directional asymmetry from the peak direction of multi-directional random waves. The suggested asymmetry parameter can express the skewness of wave direction up to ±1, which is a possible maximum value. For the case of multi-directional random waves which are propagating obliquely over a sloping bed, we found that the directional symmetry has been broken down due to the refraction. The degree of asymmetry increases as the incident angle of predominant waves increases and also the water depth decreases. The present method which considers directional asymmetry as well as symmetry gives more accurate solution than Goda and Suzuki's (1975) method which considers only directional symmetry.
Construction of intake system for Deep Ocean Water with Hybrid Installation Method
Jung, Dong-Ho ; Kim, Hyeon-Ju ; Moon, Deok-Soo ; Mang, Joo-Young ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 355~360
The construction for Deep ocean water development in land-based system was carried out for the first time in Korea. The HDPE (high density polyethylene) pipe reinforced with wire rope or steep pipe under or on the seabed was installed in order to intake DOW at the water depth of 300m and 500m by hybrid installation method which uses the bottom pulling method in shallow water and surface tow method and laying ship method in deep water. The intake point of pipeline can be kept up at the 5m above seabed in order to intake fresh DOW with a intake frame structure. The pipeline for discharging DOW including even nutrition was installed with the surface tow method. The pump pit was constructed at the DL (-) 4.8 depth for a natural head of water. It is on a trial operation for stable pumping, and 1000 ton/day of DOW can be intake with the developed system.
Hydraulic Change Analysis on Saemangeum Reservoir after Final Closure
Suh, Seung-Won ; Cho, Wan-Hei ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 361~369
Numerical tests were done in order to evaluate hydraulic changes on the inner Saemangeum Reservoir due to final closure. According to the numerical results based on 2-d ADCIRC, hydraulic characteristics such as elevation, currents, morphology and tidal system are suddenly changed by the reduction of tidal inlet width as final closure works. Tidal asymmetry between outer and inner reservoir, which has arisen after the final closure, causes super-elevation on the inner bay at least 20 centimeters. Phase lags between M2 and M4 constituents differ in both sides, i.e., it varies p-2p on outer sea and 0-p on inner bay, and this variation yields flood dominant in the outer sea while ebb dominant in the inner bay.
Application of HSPF Model for Fecal Coliform Simulation in Rural Watersheds
Ko, Jae-Young ; Park, Seung-Woo ; Jang, Tae-Il ;
Journal of The Korean Society of Civil Engineers, volume 27, issue 3B, 2007, Pages 371~378
This paper presents the results from the HSPF model applications for simulating instream fecal coliform concentrations at a rural watershed. The study watershed is the HP#7 subwatershed at the Baran Reservoir watershed, located near Suwon. The coliform concentration data were logically adjusted to reflect sampling frequencies and survival rates from on-site sampling to laboratory analyses. The model parameters were manually calibrated with the observed data from 2002 to 2003, and validated with data from 2004 to 2006. The simulated results were comparable to the observed data, showing that HSPF is applicable to simulating daily coliform loads at the test watershed. Frequency-based load duration curves were developed to assess the uncertainty associated with the conventional time-series based calibration processes. It was shown that the load duration curve generated from HSPF simulation was also similar to that from the observed data.