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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 30, Issue 6 - Dec 1997
Volume 30, Issue 5 - Oct 1997
Volume 30, Issue 4 - Aug 1997
Volume 30, Issue 3 - Jun 1997
Volume 30, Issue 2 - Apr 1997
Volume 30, Issue 1 - Jan 1997
Selecting the target year
Notes on Incompressible Theory of Hydrodynamic Pressureon Dams during Earthquakes
Jeong, Yong-Gwon ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 195~199
Classical theory of hydrodynamic pressure on dams during earthquakes is revisited and examined with linear transient theory. Because the ground motion during earthquakes is not only transient but also consists of random horizontal and vertical motions, it is proper to treat hydrodynamic pressure on dams with transient theory for random, transient earthquake motions. The present study fines that surface waves are negligible and that the present theory agrees well with the classical theory if the ground motion is horizontal and harmonic with a high frequency.
A Numerical Analysis of Flow through Open Channel Constrictions using Turbulence Model
Choe, Heung-Sik ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 201~210
To analyze the flow through open-channel constrictions using
turbulence mode, a numerical model is developed. The simulated results agree well with existing experimental data which attributes to the adequate input of turbulent eddy-viscosity by turbulence model. A stream function and velocity distributions enable the analysis of flow characteristics at the downstream of constriction. Turbulent eddy viscosities over channel are spatially varied with stream pattern. For the evaluation of rapidly varied flow, the eddy-viscosity input by turbulence model is required instead of the empirical effective viscosity to solve a shallow water equation.
Experiments on the Resistant Force of the Trees in Rivers
Lee, Jin-Won ; Yu, Dae-Yeong ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 211~223
This study was focused on the investigation of the distribution of trees which is an important factor for the improvement of the river environment, and the experimental examination of resistant force of trees to the external forces. The investigation of plant distribution performed in 11 major rivers in Korea showed that the willow family grows spontaneously over the whole country. The field experiments on the resistant force of trees were carried out on the 78 trees of 8 species in 3 different sites to estimate whether pulled out trees damage downstream hydraulic structure. The experiments were performed by the method that a backhoe drew trees and the forces were measured when the trees were overturned and pulled out. The analysis of the experimental results showed that there is a linear correlation between the resistant force and DHB (diameter at breast height).
Threshold Crossing Rate, Phase Distribution and Group Properties of Nonlinear Random Waves of finite Bandwidth
Jo, Yong-Jun ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 225~233
The nonlinear effects on the statistical properties of wave groups in terms of the average nomber of waves in a group and the mean number of waves in a high run is studied in this paper utilizing the complex envelope and total phase function, random variable transformation technique and perturbation method. It tures out that the phase distribution is modified significantly by nonlinearities and it show systematic excess of values near the mean phase and the corresponding symmetrical deficiency on both sides away from the mean. for the case of threshold crossing rate, it turns out that threshold crossing rate reaches its maxima just below the mean water level rather than zero and considerable amount of probability mass is shifted toward the larger values of water surface elevation as nonlinearity is getting profound. Furthermore, the mean waves in a high run associated with nonlinear wave are shown to have larger values than the linear counterpart. Similar trend can also be found in the average number of waves in a group.
Removal of Odor and THM from the Raw Water of Daecheong Dam
Jeon, Hang-Bae ; Yun, Gi-Sik ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 235~245
A pilot scale study for removing odor and trihalomethane formation potential (THMFP) was investigated in the standard water treatment plant equipped with ozone oxidation and granular activated carbon (GAC) adsorption processes. The removal efficiency of dissolved organic carbon (DOC) in the pilot scale standard water treatment process (PSWTP) was about 25%, however, no more removal in the ozone oxidation process. On a GAC after 30 days operation, DOC removal efficiency was about 75%. Odor removal efficiency was about 30% in PSWTP, 60% in ozone oxidation, and almost complete in well as DOC. Mid-1 and 2 that showed breakthrough in odor inducing material as well as DOC. Mid-1 and 2 chlorination was able to reduce trihalomethanes (THM) by 25% compared to prechloringation, while postchlorination alone could reduce them by 30%.
Climatological Features of Summer Precipitation in Korea
Jo, Ha-Man ; Choe, Yeong-Jin ; Gwon, Hyo-Jeong ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 247~256
Some climatological features of summer precipitation in Korea were studyed using the precipitation data of 15 stations of Korea Meteorological Administration where more than 30 years data since 1961 are available. The study included statistical analysis of precipitation by climatological normal values, and comparison of inter-annual variation of annual precipitation, summer precipitation and precipitation during the Changma. The relationships between them were also analyzed. It was revealed that, in Korea, more than half of annual precipitation was concentrated in summer season (June to August), and it was usually influenced by the Changma. The ratio of summer and Changma precipitation to the annual precipitation showed that effect of Changma was bigger in the central inland area, while comparatively smaller in the east coastal area and Cheju Island due to topographical effects. It was also shown that the fluctuation of the annual precipitation was less variable than those of summer and Changma precipitations. Thus, it was suggested that understanding the variation features of summer precipitation associated with monsoon activities was very important to figure out the change of annual precipitation for the national water resources planning.
A Study on Releases Determination Scheme for a Forecasted Flood
Gwon, O-Ik ; Sim, Myeong-Pil ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 257~268
Reservoir operators and managers need to present a rational basis of determining releases for a flood event. This study divides a forecasted flood hydrograph by two parts on the basis of non-damaging discharge, which consists of one part con,trolled by non-damaging discharge and another controlled by using flood control storage of the reservoir. In case of using flood control storage, a new reservoir operation method. called TRF (Transformed Reservoir Flood) ROM, is suggested for the operating rules during a flood to consider the reservoir security as well as the operational efficiency. This paper presents an application of the methodology to the operation of a single multipurpose reservoir at the Taechong Dam during flood and the results analyzed.alyzed.
Development of Reservoir Operating Rule Using Explicit Stochastic Dynamic Programming
Go, Seok-Gu ; Lee, Gwang-Man ; Lee, Han-Gu ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 269~278
Operating rules, the basic principle of reservoir operation, are mostly developed from maximum or minimum, mean inflow series so that those rules cannot be used in practical operating situations to estimate the expected benefits or provide the operating policies for uncertainty conditions. Many operating rules based on the deterministic method that considers all operation variables including inflows as known variables can not reflect to uncertainties of inflow variations. Explicit operating rules can be developed for improving the weakness. In this method, stochastic trend of inflow series, one of the reservoir operation variables, can be directly method, the stochastic technique was applied to develop reservoir operating rule. In this study, stochastic dynamic programming using the concepts was applied to develop optimal operating rule for the Chungju reservoir system. The developed operating rules are regarded as a practical usage because the operating policy is following up the basic concept of Lag-1 Markov except for flood season. This method can provide reservoir operating rule using the previous stage's inflow and the current stage's beginning storage when the current stage's inflow cannot be predicted properly.
A Comparative Study of Conceptual Models for Rainfall-Runoff Relationship in Small to Medium Sized Watershed -Application to Wi Stream Basin-
Lee, Jeong-Sik ; Lee, Jae-Jun ; Son, Gwang-Ik ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 279~291
This study is to evaluate the accuracy and practicality of the existing four conceptual models, two linear models of Clark and Nash model and two nonlinear models of Laruenson and WBN model, and to select an appropriate model to simulate the rainfall-runoff process in a given catchment. The variability of parameters for linear models is generally larger than that of nonlinear models. The errors in peak discharge are similar among the four conceptual models buy the errors in time to peak are quite different. Nonlinear models produce better results for time distribution than linear models. A comparison of the conceptual models to predict overall hydrograph using Friedman two-way analysis of variance by rank test indicates that nonlinear models are slightly better than linear models.
A Study on the Water Balance of the Kumgang Estuary Barrage
Hwang, Man-Ha ;
Journal of Korea Water Resources Association, volume 30, issue 3, 1997, Pages 293~301
The major objective of this study is to evaluate the water balance of the Kumgang estuary barrage, one oof the regions with the most complex water utilization system. For the purpose of present study, two approaches are proposed which consider both the natural flow and low flow conditions, respectively. In order to make the evaluation of the low flow sequences, the flood frequency of the sequences was removed. According to the results, water deficiency is expected on the target year of 1996 in case of low inflow.