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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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Korea Water Resources Association
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Volume & Issues
Volume 41, Issue 12 - Dec 2008
Volume 41, Issue 11 - Nov 2008
Volume 41, Issue 10 - Oct 2008
Volume 41, Issue 9 - Sep 2008
Volume 41, Issue 8 - Aug 2008
Volume 41, Issue 7 - Jul 2008
Volume 41, Issue 6 - Jun 2008
Volume 41, Issue 5 - May 2008
Volume 41, Issue 4 - Apr 2008
Volume 41, Issue 3 - Mar 2008
Volume 41, Issue 2 - Feb 2008
Volume 41, Issue 1 - Jan 2008
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One-dimensional Hydraulic Modeling of Open Channel Flow Using the Riemann Approximate Solver I : Model Development
Kim, Ji-Sung ; Han, Kun-Yeun ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 761~772
DOI : 10.3741/JKWRA.2008.41.8.761
The object of this study is to develop the model that solves the numerically difficult problems in hydraulic engineering and to demonstrate the applicability of this model by means of various test examples, such as, verification in the gradually varied unsteady condition, three steady flow problems with the change of bottom slope with exact solution, and frictional bed with analytical solution. The governing equation of this model is the integral form of the Saint-Venant equation satisfying the conservation laws, and finite volume method with the Riemann solver is used. The evaluation of the mass and momentum flux with the HLL Riemann approximate solver is executed. MUSCL-Hancock scheme is used to achieve the second order accuracy in space and time. This study introduce the new and simple technique to discretize the source terms of gravity and hydrostatic pressure force due to longitudinal width variation for the balance of quantity between nonlinear flux and source terms. The results show that the developed model`s implementation is accurate, robust and highly stable in various flow conditions with source terms, and this model is reliable for one-dimensional applications in hydraulic engineering.
Varied Flow Analysis for Linear Drainage Channels
Ku, Hye-Jin ; Jun, Kyung-Soo ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 773~784
DOI : 10.3741/JKWRA.2008.41.8.773
The present study was carried out to examine flow properties in linear drainage channels such as road surface drainage facilities. The finite difference formulation for the varied flow analysis was solved for flow profiles in the channels. Starting the first step at the control section, the Newton-Raphson method was applied for producing numerical solutions of the equation. We considered two types of linear drainage channels, a channel with one outlet at downstream end and a channel with two outlets at both ends. Moreover, the flow analysis for various channel slopes was performed. However, we considered channels with the two outlets of slopes satisfying the condition that the both ends are the control section. The maximum of those slopes was decided from the relation between the channel slope and the location of control section. The flow of a channel with one outlet was calculated upward and downward from the control section existing in channel or upward from the control section at downstream end. The flow of a channel with two outlets at both ends were calculated for upstream and downstream channel segments divided by the water dividend, respectively and the flow analysis was completed when the water depth at the water dividend calculated from upstream end was equal to that calculated from downstream end. If the slope was larger than the critical slope, the channel with two outlets was likely to behave like the channel with one outlet. The maximum water depth was investigated and compared with that calculated additionally from the uniform flow analysis. The uniform flow analysis was likely to lead a excessive design of a drainage channel with mild slope.
The Analysis of Characteristics of Swell in Korea using the Ubiquitous Measurement System
Jang, Bok-Jin ; Yeo, Woon-Kwang ; Lee, Jong-Kook ; Park, Kwang-Soon ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 785~795
DOI : 10.3741/JKWRA.2008.41.8.785
The swell is a major cause of interruption for the activity in a port and the ship navigation in coastal waters, coastal geographical changes, and the disaster with a loss of lives. However, many researches about the observation and the prediction of swells have not been conducted actively due to the difficulties to collect and synthesize the massive amount of long term field data for waves and meteorological information. In this study, the internet-based realtime monitoring system(Fieldbox) was developed to collect the wave data. The characteristics and main components of swells occurred in Korea were analyzed using wave data observed through the Fieldbox and the meteorological data collected by the KMA(Korea Meteorological Administration) and NASA(National Aeronautics and Space Administration). The characteristics of the swell generation patterns were analyzed using the monthly data of the Kwangan Tower between 2004 and 2006 to estimate the specific features such as sources and locations of swells generated in Korea.
The Geometric Properties of the Drainage Structures based on Fractal Tree
Kim, Joo-Cheol ; Kim, Jae-Han ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 797~806
DOI : 10.3741/JKWRA.2008.41.8.797
The geometric properties of the drainage structures are analyzed through depicting the drainage network which is composed of the whole drainage paths in the natural basin defined at the specific scale. The theoretical consideration is performed on the general structures of networks organized by ramification process based on Fractal tree and Horton`s law. The drainage network is generated via ArcGIS, ordered by Strahler`s ordering scheme and investigated with Strahler`s order. As a results of the Richardson`s method it is shown that there may exist the distinct behavioral characteristics between overland-flow and channel flow and the natural stream networks would be space-filling Fractals. As a result, it is shown that the values estimated by considering the overland-flow on being applied to the field data give the different results from the empirical method applied until now. As expected, therefore the results obtained from this study are sure to be devoted further researches on the channel networks.
Improvement of Rating Curve Fitting Considering Variance Function with Pseudo-likelihood Estimation
Lee, Woo-Seok ; Kim, Sang-Ug ; Chung, Eun-Sung ; Lee, Kil-Seong ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 807~823
DOI : 10.3741/JKWRA.2008.41.8.807
This paper presents a technique for estimating discharge rating curve parameters. In typical practical applications, the original non-linear rating curve is transformed into a simple linear regression model by log-transforming the measurement without examining the effect of log transformation. The model of pseudo-likelihood estimation is developed in this study to deal with heteroscedasticity of residuals in the original non-linear model. The parameters of rating curves and variance functions of errors are simultaneously estimated by the pseudo-likelihood estimation(P-LE) method. Simulated annealing, a global optimization technique, is adapted to minimize the log likelihood of the weighted residuals. The P-LE model was then applied to a hypothetical site where stage-discharge data were generated by incorporating various errors. Results of the P-LE model show reduced error values and narrower confidence intervals than those of the common log-transform linear least squares(LT-LR) model. Also, the limit of water levels for segmentation of discharge rating curve is estimated in the process of P-LE using the Heaviside function. Finally, model performance of the conventional log-transformed linear regression and the developed model, P-LE are computed and compared. After statistical simulation, the developed method is then applied to the real data sets from 5 gauge stations in the Geum River basin. It can be suggested that this developed strategy is applied to real sites to successfully determine weights taking into account error distributions from the observed discharge data.
Site Suitability and Developable Amount Assessment for Riverbank Filtration in the Han River (I)
Lee, Sang-Il ; Lee, Sang-Sin ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 825~834
DOI : 10.3741/JKWRA.2008.41.8.825
Riverbank filtration for water supply has been employed for about 150 years in developed countries. In Korea, the feasibility of riverbank filtration has been investigated since 1990`s for large river basins, to find a solution to stably meet the ever-increasing demand for water. Recently, some cites in the Nak-dong River Basin have been supplying the water through riverbank filtration. This research studies the feasibility of riverbank filtration in Seoul. Analytic Hierarchy Process (AHP), which selects the most optimal alternative by hierarchically classifying various attributes and then quantifying the importance of each attribute, was applied to candidate locations for the selection of riverbank filtration site. The Kwangnaru district, which has advantages in water quality and close connectivity to the existing water purification facility, was selected as the most optimal site.
Site Suitability and Developable Amount Assessment for Riverbank Filtration in the Han River (II)
Lee, Sang-Il ; Yoo, Sang-Yeon ; Lee, Sang-Sin ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 835~843
DOI : 10.3741/JKWRA.2008.41.8.835
In Korea, riverbank filtration has drawn attention since 1990`s as an alternative having potential to stably meet the ever-increasing water demand. Some cities located in the Nak-dong River Basin are currently supplying water through riverbank filtration. This research is on the application of riverbank filtration for stable water quality in Seoul. For this purpose, we have evaluated developable amount of water with riverbank filtration for the Han River. This paper focuses on the Kwangnaru site, which was selected through a systematic analysis in the companion paper. We have conducted groundwater modeling for a proposed system of wells and an artificial lake. In the Kwangnaru district, the river length to constitute a well system was identified to be about 1,200m, due to the topography and the field condition such as ecosystem preservation zone. After many design changes, it was found that the maximum developable amount of
/year could be obtained, when 16 pumping wells were built in every 80 meters along with an artificial lake upstream.
An Experimental Study to Evaluate Hydraulic Characteristics and Stability of Scour Protection for Historic Site Restoration of Woljeong-gyo
Kang, Joon-Gu ; Yeo, Hong-Koo ; Son, Byung-Ju ; Ji, Un ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 845~854
DOI : 10.3741/JKWRA.2008.41.8.845
The old bridge of Woljeong-gyo, which has the fluvial history and culture, represents the ancient construction and civil engineering techniques. It is the oldest stone bridge in Korea and currently restored with its vicinities. In this study, the experimental model was used to analyze the hydraulic characteristics, the local pier-scour depth without scour protection, and the stability of riprap protection using the old grid type panels and stones for Woljeong-gyo of the study area. The water levels were increased around 30cm due to the restored bridge piers and foundations and the effects went up to 200m upstream. The maximum scour depth of 5.4m was measured and the scour protection tests were performed with the riprap size calculated using empirical equations and the existing scour protection range. The riprap of the existing scour protection in the upstream side was broken away, while the riprap of extended scour protection was very stable for the design flood condition of Woljeong-gyo area.
A Surface Image Velocimetry Algorithm for Analyzing Swaying Images
Yu, Kwonk-Yu ; Yoon, Byung-Man ; Jung, Beom-Seok ;
Journal of Korea Water Resources Association, volume 41, issue 8, 2008, Pages 855~862
DOI : 10.3741/JKWRA.2008.41.8.855
Surface Image Velocimetry (SIV) is an instrument to measure water surface velocity by using image processing techniques. To improve its measuring accuracy, it is essential to get high quality images with low skewness. A truck-mounted SIV system would be a good way to get images, since its crane gives high altitude to the images. However, the images taken with a truck-mounted SIV would be swayed due to the movement of crane and the camera by winds. In that case, to analyze the images, it is necessary to compensate the side sway in the images. The present study is to develop an algorithm to analyze the swayed images by combining common image processing techniques and coordinate transform techniques. The system follows the traces of some selected fixed points and calculates the displacements of the video camera. By subtracting the average velocity of the fixed points from that of grid points, the velocity fields of the flow can be corrected. To evaluate the system`s performance, two image sets were used, one image set without side sway and another set with side sway. The comparison of their results showed very close with the error of around 6 %.