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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Civil Engineers
Journal Basic Information
Journal DOI :
Korean Society of Civil Engeneers
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Volume & Issues
Volume 17, Issue 3_6 - Nov 1997
Volume 17, Issue 2_6 - Nov 1997
Volume 17, Issue 1_6 - Nov 1997
Volume 17, Issue 3_5 - Sep 1997
Volume 17, Issue 2_5 - Sep 1997
Volume 17, Issue 1_5 - Sep 1997
Volume 17, Issue 3_4 - Jul 1997
Volume 17, Issue 2_4 - Jul 1997
Volume 17, Issue 1_4 - Jul 1997
Volume 17, Issue 3_3 - May 1997
Volume 17, Issue 2_3 - May 1997
Volume 17, Issue 1_3 - May 1997
Volume 17, Issue 3_2 - Mar 1997
Volume 17, Issue 2_2 - Mar 1997
Volume 17, Issue 1_2 - Mar 1997
Volume 17, Issue 3_1 - Jan 1997
Volume 17, Issue 2_1 - Jan 1997
Volume 17, Issue 1_1 - Jan 1997
Selecting the target year
Comparison of Pipe Friction Factor Formulas
Yoo, Dong-Hoon ; Wun, Yoo-Seung ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 185~185
Since Chezy's mean-velocity equation was published. many researchers have tried to compute friction coefficient using the modified form of Chezy equation. But as the empirical parameters used in the equations are not clearly defined because they depends on engineer's experience and it is considerably difficult to estimate them accurately. serious mis-understandings may have been drawn in the computation of pipe friction factor Because of these reasons. the present study clarifys the limit and problems of the empirical equations by the comparison of these pipe friction coefficients, and it offers a guide line in the use of pipe friction factor equations and discusses the difference and similarity of friction factor equations of composite surface which Yoo (1995) and Barr (1975) proposed. On the other hand. this study re-analyzed the experimental data of Colebrook (1938) to estimate the equivalent roughness height and probability and confirmed the validation of two methods : mean zero velocity point and mean friction factor.
Feasibility Assessment for Small Hydro Power Sites in Korea
Park, Wan-Soon ; Lee, Chul-Hyung ; Shim, Myung-Pil ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 197~197
The methodology and feasibility analysis model for small hydro power(SHP) sites has been studied and developed. It consists of two main part. the perfomance prediction model to estimate the performance characteristics and economics anaysis model to evaluate economical characteristics for SHP sites. The performance characteristics and feasibility assessment for SHP sites were analyzed, using developed models. Also, primary design specifications such as design flowrate. capacity, load factor were estimated and discussed for surveyed sites in Korea and feasibility was suggested through analyzing the investment. unit cost and payback period. It was found that the developed model in this study is useful tool to estimate feasibility assessment for SHP sites in Korea.
A Study on the Low Flow Frequency Analysis in Korea
Heo, Jun-Haeng ; Kim, Kyung-Duk ; Cho, Won-Cheol ; Shim, Myung-Seob ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 207~207
The frequency analyses for low flows of 14 sites were performed. In order to select an appropriate distribution, 13 probability distributions were employed: gamma-2, gamma-3, GEV, Gumbel, log-Gumbel-2, log-Gumbel-3, lognormal-2, lognormal-3, log-Pearson type III. Weibull-2, Weibull-3, Wakeby-4, and Wekeby-5 distributions. The parameters were estimated based on the methods of moments, maximum likelihood, and probability weighted moments. The goodness of fit tests such as
-test, Kolmogorov-Smirnov test, and Clamor von Mises test were performed as well as graphical analysis. Moment diagram and L-moment diagram showed that there is no certain probability distribution for low flows. Thus, an appropriate distribution of each site was selected based on goodness of fit tests and graphical analysis, and the quantiles of low flows were estimated using those distributions.
Surface Resistance as a Function of Soil Moisture
Rim, Chang-Soo ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 217~217
Meteorological, flux and soil moisture data measured from small semiarid watershed during the summer rainy period were used to find the relationship between actual evapotranspiration and surface resistance as a function of soil moisture content measured at several different depths (5 cm, 20 cm and 60 cm). The surface resistance derived from Penman-Monteith equation suggested by Monteith was used to find the relationship. Furthermore, the diurnal variation of surface resistance according to soil moisture condition was studied. using the data measured during the relatively dry and wet days. The study results show that surface resistance during the dry day is relatively higher than that during the wet day, and therefore there is less actual evapotranspiration. The surface resistance exhibits a marked diurnal variation in the afternoon with definite decrease in the morning. The study results also indicate that the correlation between soil moisture content and surface resistance decreases as thickness of soil increases.
A Comparative Study of Real Time Measurement and Estimation of Scour at Bridges due to Flood
Yoon, Yong-Nam ; Ho, Jung-Seok ; Lee, Jae-Soo ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 225~225
The objective of the present study is to investigate the mechanism involved in the local scouring and infilling around a bridge pier during a flood. The river bed elevation changes at bridge piers are measured on a real time basis throughout a flood event by a fathometer. and the maximum scour depths at bridge piers are estimated with 2-di-mensional hydrodynamic model, TABS-MD and C.S.U. equation. which is a popular formula for calculation of the local scour depths. As a result, the estimated scour depths are found to be much larger than the measured because the empirical scour depth formulas, such as C.S.U. equation, are generally developed under a steady flow condition in a laboratory channel, whereas the scouring process in rivers during a flood occurs under unsteady flow conditions. Therefore, an empirical formula always overestimates the actual maximum scour depth around a pier, which is on a safe side in view of the bridge foundation design. It is suggested that more studies should be accumulated to improve the estimation method of maximum scour depth around a bridge pier.
An Effective Decision Support Method of Regularization Parameter on Separating Hydrologic Response
Seong, Kee-Won ; Shim, Myung-Pil ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 235~235
The ridge regression (RR) which makes up for the weakness of ordinary least squares method has been suggested to separate the unit hydrograph or the hydrologic response. This regression method applies the intended bias to minimize mean-squared-error in statistical aspects. but it has been used the attenuation effect of the response to be characterized as realistic by experienced hydrologists. As recent research on this issue it is proposed that the Nash model using the result of the RR with the freely choosed proper bias is developed. But the relation between the regularization parameter and the response should be prior examined because this technique is deeply influenced on the regularization parameter which is function of bias. The connection between regularization parameter and the model selection criteria is analyzed by statistical tool to verify this regression problem. This process can be effective decision support method to derivation of the hydrologic response.
Establishment of Explicit Type Formula of Wave Breaking Condition
Lee, Jong-Seol ; Chung, Il-Moon ; Cho, Won-Cheol ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 243~243
Since the wave breaking parameter has been shown that the function of Iribarren number, new wave breaking condition formula based on this relationship was suggested. But this formula has implicit form, so the difficulty remains in computation. In this study explicit formula of local wave breaking condition is established to facilitate computational effort. The results from original formula show 'S' shape in semi logarithm paper, so growth function is selected to fit this curve using least square method. The results from explicit formula show good agreement with those from implicit one. so the existing formula can be replaced with new one.
A Study on Numerical Analysis of Breaking Waves by the Submerged Breakwater in the Numerical Wave Tank
Kim, Do-Sam ; Hur, Dong-Soo ; Yun, Duk-Yong ; Jeong, Yeon-Tae ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 251~251
The objective of this study is to regenerate breaking wave phenomena using the boundary element method and open boundary which is newly proposed in this study Generally, it is impossible to apply open boundary to the numerical analysis of breaking waves, because open boundary conditions have been on the basis of Eulerian fluid motion so far. The numerical wave tank of sponge theory and Euler-Lagrangian discription in the free water surface are used, and waves are generated by line source. It is shown that the wave profile generated by this method is very stable, and the breaking phenomena of waves on the structure are well regenerated. Especially. numerical results give good agreement with one obtained from strongly nonlinear wave model in case of non-breaking waves. Therefore, it is concluded that this numerical method will be applicable to the prediction of wave transformation by the coastal structure in case of non-breaking waves. Besides, applying to the trapezoidal submerged breakwater with one and two rows. we verified that this numerical method is the useful prediction method for breaking wave profiles and wave transformation by the submerged breakwater.
A Study on the Wastewater Treatment Characteristics of the Indirectly Aerated Fluidized Bed - Effect of Temperature and pH -
Ahn, Song-Yeob ; Lee, Jeoung-Su ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 261~261
The characteristics of wastewater treatment according to condition of temperature and pH in indirectly aerated fluidized bed of sand media were studied experimentally, and the obtained results were as follows; Under the indirect aeration. the BOD removal efficiency rised continually in the range of temperature
but under air-aeration of about
. filamentous bacteria came into existence due to insufficient dissolved oxygen, and the BOD removal efficiency came down. On the other hand. under oxygen-aeration filamentous bacteria disappeared as time goes by (about 3 days). A factor of temperature correction was
, and a factor of pH correction was
in the pH range of 5 to 12, but was dropped to
at pH under 4. Under the conditions of pH 4 or below, filamentous bacteria exuberated grossly. the phenomenon of bioparticle colligations showed and the BOD removal effinciency came down grossly.
Design Parameters of Granular Activated Carbon Adsorption Process to Remove Pesticides for a Small Plant in Rural Area
Shin, Kyoung-Hwa ; Wang, Chang-Keun ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 269~269
Small scale tests and pilot plant operation for removing DOC and organophosphorus pesticides were peformed to select optimal processes and to obtain design parameters. As the results of Pilot operation, both GAC and
/GAC processes are effective to remove many organic pollutants in a tributary of Keum River. Since the influent DOC concentrations of a tributary of Keum River was relatively low, treatable bed volume with 1.7m bed depth was over 37,000 and service duration was over 8 months without reactivation or replacement to achieve the treatment objective of 1.0 mg/l DOC. Although adsorption capacities of pesticides were reduced with background DOC, judging from the results of small column tests with background DOC (DOC= 1.5 mg/l), treatable bed volume was
in Parathion and
in Malathion to achieve the treatment objective of drinking water quality standard. When GAC adsorbers are designed adequately, DOC and the intermittently occurring organophosphorus pesticides can be controlled.
Evaluation and Analysis of Streaming Current Detector in Coagulation Process-Full Scale Test
Han, Moo-Young ; You, Jae-Oh ; Lim, Boo-Sang ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 2_3, 1997, Pages 277~277
In this study, a technique using SCD is tested and evaluated by full scale test in a water treatment plant. The coagulant dosage was varied within 30% of normal dosage and the SCD reading was continuously monitored by on-line. SCD responded well with the coagulant dosage. The effect of other raw water characteristic such as turbidity. pH, conductivity, temperature was also evaluated. Overall, it is shown that SCD technique is scientifically sound and easy to operate. It will give the water treatment plant operator much reliability if it is used together with existing coagulant control method. especially when raw water conditions change rapidly in water treatment plant.