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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korea Water Resources Association
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Journal DOI :
Korea Water Resources Association
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Volume & Issues
Volume 32, Issue 6 - Dec 1999
Volume 32, Issue 5 - Oct 1999
Volume 32, Issue 4 - Aug 1999
Volume 32, Issue 3 - Jun 1999
Volume 32, Issue 2 - Apr 1999
Volume 32, Issue 1 - Feb 1999
Selecting the target year
Measurement do Water Content in Sandy-Gravelly Soils using Time Domain Reflectometry
Kim, Dong-Ju ; Kim, Jeong-Seok ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 215~223
Recently, measurement of soil moisture contents using TDR (time domain reflectometry) has been proven to be viable technique. The first empirical model proposed by Topp et al. (1980) has been widely used to determine moisture contents of soils from the TDR-measured dielectric constants. However, applicability of the model was limited to medium-textured soils. In this study, we investigate the applicability of the model to sandy-gravelly soils. Calibration experiments consisted of measurement on travel time of electromagnetic waveform along the parallel TDR rods inserted into samples and gravimetric determination of soil moisture contents. The experiments are performed for two sets of samples different in the length and each set consisted of seven different particle size distributions with various gavel contents. The calibration results show that the Topp equation overestimated the measured moisture content for a given dielectric constant by 3 to 8%. We therefore propose new empirical relationships valid for sandy-gravelly soils.
A Comparative Study of 2-Dimensional Turbulence Models for Thermal Discharge
Choi, Hung-Sik ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 225~235
For a comparative evaluation of three turbulence models in the analyses of thermal discharge behavior into a crossflow, a 2-dimemsional near-field numerical model is developed. The selected models are k-
and k-ι turbulence models as a 2-equation turbulence model and a 4-equation turbulence model in which the transport equations for mean of the temperature fluctuation squared and its dissipation rate for the consideration of buoyancy production and turbulent heat flux terms are added to a k-
turbulence model. The developed models are applied to a steady flow in an open channel with simple geometry and the numerical results agree with the existing experimental data. Numerical results of buoyancy induced gravitational lateral spreading by 4-equation turbulence model agree with the experimental data better than those of 2-quation turbulence models. The flow patterns by 4 and 2-equation turbulence models are similar.
Application of Hermite-Collocation Method for Unsteady Flow Analysis
Han, Geon-Yeon ; Lee, Eul-Rae ; Park, Jae-Hong ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 237~246
A finite element model is studied to simulate unsteady free surface flow based on dynamic wave equation and collocation method. The collocation method is used in conjunction with Hermite polynomials, and resulting matrix equations are solved by skyline method. The model is verified by applying to hydraulic jump, nonlinear disturbance propagation and dam-break flow in a horizontal frictionless channel. The computed results are compared with those by Bubnov-Galerkin and Petrov-Galerkin methods. It is also applied to the North Han River to simulate the floodwave propagation. The computed results have good agreements with those of DWOPER model in terms of discharge hydrographs. The suggested model has proven to be one of the promising scheme for simulating the gradually and rapidly varied unsteady flow in open channels.
Derivation of Rainfall Intensity-Duration-Frequency Equation Based on the Approproate Probability Distribution
Heo, Jun-Haeng ; Kim, Gyeong-Deok ; Han, Jeong-Hun ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 247~254
The frequency analyses of annual maximum rainfall data for 22 rainfall gauging stations is Korea were performed. The method of moments (MOM), maximum likelihood (ML), and probability weighted moments (PWM) were used in parameter estimation. The GEV distribution was selected as an appropriate model for annual maximum rainfall data based on parameter validity condition, graphical analysis, separation effect, and goodness of fit tests. For the selected GEV model, spatial analysis was performed and rainfall intensity-duration-frequency equation was derived by using linearization technique. The derived rainfall intensity-duration-frequency equation can be used for estimating rainfall quantiles of the selected stations with convenience and reliability in practice.
An Experimental Study on Local Scour around Abutment
An, Sang-Jin ; Hwang, Bo-Yeon ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 255~263
The laboratory datas are for local scour depth measurement at vertical-wall abutment. These include the data to demonstrate the effects of local scour depth of abutment nose shape, alignment angle, flow depth and flume slope. The pattern of local scour were measured and analyzed the abutments which are rectangular, sharp, chamfered rectangular and ablong nose shapes. The experiments were carried out with varing the flume slope and alignment algle increasing flow depth every step in 1cm for four abutment types on the live-bed scour conditions. The flume slope and alignment angle were varied in five cases : for latter 30
, for former 0.01%, 0.03%, 0.05%, 0.1% and 0.2%. The maximum scour depths were analyzed for the shaped of abutment nose with rectangular, ablong, chamfered rectangular and sharp in order. The results of the experiments show that the scour depth varies not only with abutment nose shapes and alignment angle but also with the flow depth and flume slope.
Low Flow Frequency Analysis of Steamflows Simulated from the Stochastically Generated Daily Rainfal Series
Kim, Byeong-Sik ; Gang, Gyeong-Seok ; Seo, Byeong-Ha ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 265~279
In this study, one of the techniques on the extension of low flow series has been developed, in which the daily streamflows were simulated by the Tank model with the input of extended daily rainfall series which were stochastically generated by the Markov chain model. The annual lowest flow serried for each of the given durations were formulated form the simulated daily streamflow sequences. The frequency of the estimated annual lowest flow series was analyzed. The distribution types to be used for the frequency analysis were two-parameter and three-parameter log-normal distribution, two-parameter and three-parameter Gamma distribution, three-parameter log-Gamma distribution, Gumbel distribution, and Weibull distribution, of which parameters were estimated by the moment method and the maximum likelihood method. The goodness-of-fit test for probability distribution is evaluated by the Kolmogorov-Sminrov test. The fitted distribution function for each duration series is applied to frequency analysis for developing duration-low flow-frequency curves at Yongdam Dam station. It was shown that the purposed technique in this study is available to generate the daily streamflow series with fair accuracy and useful to determine the probabilistic low flow in the watersheds having the poor historic records of low flow series.
Optimization Technique for Estimation of Potential Hydroelectric Energy at Existion Ahricultural Reservoir
An, Tae-Jin ; Ryu, Hui-Jeong ; Park, Jeong-Eung ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 281~289
Small-scale hydropower projects at existing agricultural reservoirs can contribute to produce electric energy by maximizing the use of releases from the reservoirs. The irrigation water duration, the reservoir hydropower simulation, and the nonlinear programming model are employed to estimate potential hydroelectric energy at an existing reservoir. The nonlinear programming model consists of finding a maximum hydroelectric energy subject to irrigation water demand constraints. The sample reservoir given a set of inflow and irrigation water is considered. The optimal solutions by the optimization model yield the most hydroelectric energy for the analysis period in the three methods. Consequently, the nonlinear programming model uses the most water for hydropower generation with respect to the total inflow of the sample reservoir. It is also found that additional storage by increasing the normal water level of the sample reservoir does not significantly increase the annual hydroelectric energy for the given reservoir. It is expected that the optimization model and the proposed procedure for estimating potential hydroelectric energy can be applied to evaluate feasibility analysis for small scale hydropower additions at existing agricultural dams.
Derivation of Snyder's Synthetic Unit Hydrograph Using Fractal Dimension
Go, Yeong-Chan ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 291~300
The Snyder's synthetic unit hydrograph method is selected to apply the concept of the fractal dimension by stream order for the practicable rainfall-runoff generation, and fourth types of the Snyder's relation are derived from topographic and observed unit hydrograph data of twenty-nine basins. As a result of the analysis of twenty-nine basins and the verification of two basins, the Snyder's relation which considers the fractal dimension of the stream length and uses calculated unit hydrograph data shows the best result. The concept of the fractal dimension by stream order is applied to the Snyder's synthetic unit hydrograph method. The topographic factors, used in the Snyder's synthetic unit hydrograph method, which have a property of the stream length like
(mainstream length) and
(length along the mainstream to a point nearest the watershed centroid) were considered. In order to simplify the fractal property of stream length, it is supposed that
has not the fractal dimension and the stream length between
) has the fractal dimension of 1.027. From the utilization of this supposition, a new Snyder's relation which consider the fractal dimension of the stream length occurred by the map scale used was finally suggested.
Analysis of Analytical Models and Numerical Model for Evaluating Induced Infiltration Rate
Lee, Do-Hun ; Lee, Eun-Tae ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 301~310
In this paper a numerical model and two analytical models in the hydraulically connected stream-aquifer system were analyzed to compare the induced infiltration rate curves derived from each model. And we also examined the effects of anisotropy of hydraulic conductivity and the direction of the ambient ground water flow on the quantification of the induced infiltration rate. The induced infiltration rate curve determined by models is very simple and useful for estimating the induced infiltration rate since it contains only four physical variables such as the induced infiltration rate, the pumping rate, the distance between the pumping well and the stream, and the ambient ground water flow rate. Under the conditions tested in this paper the induced infiltration rate curves resulted from the Wilson's analytical model and FEWA numerical model were in good agreement, and the anisotropic ratio of hydraulic conductivity was evaluated as a physical factor which influences the behaviour of the induced infiltration rate curve. The methods and results of the paper might Icad to improve the understanding of the induced infiltration phenomenon and can be applied to the planning and disign of pumping well and the optimal determination of the induced infiltration rate and pumping rate for water quality management of the water supply wells.
Submerged Type Water Purification System using Hollow Fiber Microfiltration Membrane
Jeong, Gyu-Yeong ; Kim, Hyeong-Su ; Im, Jong-Seong ;
Journal of Korea Water Resources Association, volume 32, issue 3, 1999, Pages 311~319
Membrane separation process is considered as an alternative of conventional water purification system using coagulationㆍsedimentation＋sand filtration. In this study, it was examined that the application possibility of Hollowfiber Microfiltration membrane for water purification process. A
scale pilot plant was used for studying the possibility of long-term operation and the stability of water quality under the optimum conditions, 0.03m/h permeate flux, filtration for 10 minutes, pause for 2 minutes(including air-scrubbing for 30 seconds), obtained by lab-scale experiment. As a result, it was proved stability of pilot plant over one year and filtrate quality(Turbidity. SS etc). Therefore, it was proved that membrane separation process using Hollowfiber Microfiltration membrane can be applied for water purification system