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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 28, Issue 6D - Nov 2008
Volume 28, Issue 6C - Nov 2008
Volume 28, Issue 6B - Nov 2008
Volume 28, Issue 6A - Nov 2008
Volume 28, Issue 5D - Sep 2008
Volume 28, Issue 5C - Sep 2008
Volume 28, Issue 5B - Sep 2008
Volume 28, Issue 5A - Sep 2008
Volume 28, Issue 4D - Jul 2008
Volume 28, Issue 4C - Jul 2008
Volume 28, Issue 4B - Jul 2008
Volume 28, Issue 4A - Jul 2008
Volume 28, Issue 3D - May 2008
Volume 28, Issue 3C - May 2008
Volume 28, Issue 3B - May 2008
Volume 28, Issue 3A - May 2008
Volume 28, Issue 2D - Mar 2008
Volume 28, Issue 2C - Mar 2008
Volume 28, Issue 2B - Mar 2008
Volume 28, Issue 2A - Mar 2008
Volume 28, Issue 1A - Jan 2008
Volume 28, Issue 1D - Jan 2008
Volume 28, Issue 1C - Jan 2008
Volume 28, Issue 1B - Jan 2008
Selecting the target year
Influence of Snow Accumulation and Snowmelt Using NWS-PC Model in Rainfall-runoff Simulation
Kang, Shin Uk ; Rieu, Seung Yup ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 1~9
The impact of snow accumulation and snowmelt in rainfall-runoff modelling was analyzed for the Soyanggang dam basin by comparing the measured and simulated discharges simulated by the NWS-PC model. Sugawara's conceptual model was used to simulate the snow accumulation and snowmelt phenomena and NWS-PC model was employed to simulate rainfall-runoff. Parameters in model calibration were estimated by the Multi-step Automated Calibration Scheme and optimized using SCE-UA algorithm in each step. The results of the model calibration and verification show that the model considering snowmelt process is better than the one without consideration of snowmelt under the performance criteria such as RMSE, PBIAS, NSE, and PME. The measured discharge time series has over 60 days of persistence. Correlograms for each simulation showed that the simulated discharge with snowmelt model reproduce the persistence closely to the measured discharge's while the one without snow accumulation and snowmelt model reproduce only 20 days of persistence. The study result indicates that the inclusion of snow accumulation and snowmelt model is important for the accurate simulation of rainfall-runoff phenomena in the Soyanggang dam basin.
Increase of Spillway Discharge by Labyrinth Weir
Seo, Il Won ; Song, Chang Geun ; Park, Se Hoon ; Kim, Dong Joo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 11~20
The spillway type of small and midsize dams in Korea is almost overflow weir. To examine flood control capacity of overflow spillway, FLOW-3D was applied to Daesuho dam and analysis was focused on the discharge of dam spillway by changing weir shape. Overflow phases and discharges of linear labyrinth weir and curved labyrinth weir were compared with those of existing linear ogee weir. Hydraulic model experiment was performed to verify numerical result. Verification results showed that overflow behaviors and flow characteristics in the side channel by hydraulic model experiment and numerical simulation are well matched, and water surface elevation at side wall coincides with each other. When the reservoir elevation was increased up to design flood level, in case of the linear ogee weir the flow over the crest ran through smoothly in the side channel, whereas in cases of linear labyrinth weir and curved labyrinth weirs, the flow discharge was increased by 40 cms, and the flow over the weir crest, rotating counter-clockwise, was submerged in the side channel. The results of the water level-discharge curve revealed that labyrinth weir can increase discharge by 71% compared to the discharge of linear ogee weir at low reservoir elevation since it can have longer effective length. But as water surface elevation rises, the slope of water level-discharge curve of labyrinth weir becomes milder by submergence and nappe interference in the side channel.
Calibration and Estimation of Parameter for Storage Function Model
Kim, Bum Jun ; Kawk, Jae Won ; Lee, Jin Hee ; Kim, Hung Soo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 21~32
Flood forecasting is a very important tool as one of nonstructural measures for reduction of flood damages in life and property and its accuracy is also an important factor. However, when we apply the Storage Function Model(SFM) which is mainly used for the flood forecasting system in Korea, the determination of the parameters is very important but it is difficult. So, the parameters have been calibrated by using an empirical formulas and judgement of hydrologist. Hence, in this study we perform the sensitivity analysis to understand the parameter characteristics and establish the ranges of parameters of the SFM. Also we do the parameter calibration by using the optimization techniques and objective functions, and evaluate their performances. Especially, we suggest a method to determine proper parameters by using a objective function which can be obtained from flood events. So, we use the suggested method for parameter estimation and compare the estimated parameters with the previously reported parameters. As a result of the application, the estimated parameters by the suggested method showed better than them from the previously reported parameters.
Flood Mitigation Planing for a Basin Using a Decision Tree Model
Byeon, Sungho ; Kang, Hyunjin ; Han, Jeongwoo ; Kim, Tae-Woong ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 33~40
Intensive rainfalls in wet season (June~September) result in serious flood damage which is about 95% of natural hazard in Korea. Recently, in order to cope with repeated flood hazard, comprehensive flood control plans have been carried out in large basins in Korea. The plans suggest structural alternative plans for flood mitigation as well as non-structural plans. In this study, a practical method using a decision tree was developed to systematically allocate structural facilities for flood control, which maximizes the flood control capacity in a basin. This study also presents a practical guidance to organize structural defensive alternatives for a comprehensive flood control plan in a large basin.
On the Change of Extreme Weather Event using Extreme Indices
Kim, Bo Kyung ; Kim, Byung Sik ; Kim, Hung Soo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 41~53
Unprecedented weather phenomena are occurring because of climate change: extreme heavy rains, heat waves, and severe rain storms after the rainy season. Recently, the frequency of these abnormal phenomena has increased. However, regular pattern or cycles cannot be found. Analysis of annual data or annual average data, which has been established a research method of climate change, should be applied to find frequency and tendencies of extreme climate events. In this paper, extreme indicators of precipitation and temperature marked by objectivity and consistency were established to analyze data collected by 66 observatories throughout Korea operated by the Meteorological Administration. To assess the statistical significance of the data, linear regression and Kendall-Tau method were applied for statistical diagnosis. The indicators were analyzed to find tendencies. The analysis revealed that an increase of precipitation along with a decrease of the number of rainy days. A seasonal trend was also found: precipitation rate and the heavy rainfall threshold increased to a greater extent in the summer(June-August) than in the winter (September-November). In the meanwhile, a tendency of temperature increase was more prominent in the winter (December-February) than in the summer (June-August). In general, this phenomenon was more widespread in inland areas than in coastal areas. Furthermore, the number of winter frost days diminished throughout Korea. As was mentioned in the literature, the progression of climate change has influenced the increase of temperature in the winter.
Flood Risk Assessment with Climate Change
Jeong, Dae-Il ; Stedinger, Jery R. ; Sung, Jang-Hyun ; Kim, Young-Oh ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 55~64
The evidence of changes in the climate system is obvious in the world. Nevertheless, at the current techniques for flood frequency analysis, the flood distribution can not reflect climate change or long-term climate cycles. Using a linear regression and a Mann-Kendall test, trends in annual maximum precipitation and flood data for several major gauging sites were evaluated. Moreover, this research considered incorporating flood trends by climate change effects in flood frequency analyses. For five rainfall gauging sites (Seoul, Incheon, Ulleungdo, Jeonju, and Gangneung), upward trends were observed in all gauged annual maximum precipitation records but they were not statistically significant. For three streamflow gauging sites (Andong Dam, Soyanggang Dam, and Daecheong Dam), upward trends were also observed in all gauged annual maximum flood records, but only the flood at Andong Dam was statistically significant. A log-normal trend model was introduced to reflect the observed linear trends in annual maximum flood series and applied to estimate flood frequency and risk for Andong Dam and Soyanggang Dam. As results, when the target year was 2005, 50-year floods of the log-normal trend model were 41% and 21% larger then those of a log-normal model for Andong Dam and Soyanggang Dam, respectively. Moreover, the estimated floods of the log-normal trend model increases as the target year increases.
Trends of Annual and Monthly FAO Penman-Monteith Reference Evapotranspiration
Rim, Chang-Soo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 65~77
The effects of climatic changes owing to urbanization, geographical and topographical conditions on annual and monthly FAO Penman-Monteith (FAO P-M) reference evapotranspiration, and energy and aerodynamic terms of FAO P-M reference evapotranspiration were studied. In this study, 21 climatological stations were selected. The statistical methods applied for trend analysis are Spearman rank test, Sen's test, linear regression analysis and analysis of actual variation ratio. Furthermore, the cluster analysis was applied to cluster 21 study stations by considering the geographical and topographical characteristics of study area. The study results indicate that urbanization affects the trend and amount of FAO P-M reference evapotranspiration, energy term and aerodynamic term; however, the result of Sen's test indicates that urbanization does not significantly affect the magnitude of trend (Sen's slope). The energy term increased at study stations located in coastal area; however, decreased at study stations located in inland area. The topographical slope of study area did not significantly influence on the trend of energy term. The aerodynamic term increased in both coastal area and inland area, indicating much significantly increasing trend in inland area, and it was also affected by the topographical slope of the study area.
Water Quality Simulations After Completion of Saemangeum Reservoir Construction
Suh, Seung Won ; Lee, Hwa Young ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 79~93
Water quality simulations on the Saemangeum inner reservoir have been carried out using EFDC model to understand water quality variations caused by abrupt physical changes due to closing of tidal barrier. According to hydrodynamic simulation, model reproduces not only outer regional dynamics but also inner superelevation very well. Calibration and verification of water quality models accomplished using observed data taken before closing. Also sensitivity tests regarding riverine discharges and tidal flats were done. Due to enlarging of always wet zone caused by super elevation on inner tidal flats, predicted DO decreases at that region as a result of SOD. Moreover shrink of mixing zone after closing of dike causes deteriorating of water quality showing DO as 2 mg/L during summer at Mangyeong and Dongjin estuaries, however it does not spread to middle part of the reservoir. Vertical stratification occurs after closing and shows vertical differences in DO concentration at least 6 mg/L to 7 mg/L in summer season. Most part of the reservoir is getting stratified and it leads to an oxigen deficit zone near bottom.
Suspension of Sediment over Swash Zone
Cho, Yong Jun ; Kim, Kwon Soo ; Ryu, Ha Sang ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 95~109
We numerically analyzed the nonlinear shoaling, a plunging breaker and its accompanying energetic suspension of sediment at a bed, and a redistribution of suspended sediments by a down rush of preceding waves and the following plunger using SPH with a Gaussian kernel function, Lagrangian Dynamic Smagorinsky model (LDS), Van Rijn's pick up function. In that process, we came to the conclusion that the conventional model for the tractive force at a bottom like a quadratic law can not accurately describe the rapidly accelerating flow over a swash zone, and propose new methodology to accurately estimate the bottom tractive force. Using newly proposed wave model in this study, we can successfully duplicate severely deformed water surface profile, free falling water particles, a queuing splash after the landing of water particles on the free surface and a wave finger due to the structured vortex on a rear side of wave crest (Narayanaswamy and Dalrymple, 2002), a circulation of suspended sediments over a swash zone, net transfer of sediments clouds suspended over a swash zone toward the offshore, which so far have been regarded very difficult features to mimic in the computational fluid mechanics.
Explicit Solution of Wave Dispersion Equation Using Recursive Relation
Lee, Changhoon ; Jang, Hochul ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 111~114
Explicit solutions of the wave dispersion equation are developed using the recursive relation in terms of the relative water depth. We use the solutions of Eckart (1951), Hunt (1979), and the deep-water and shallow-water solutions for initial values of the solution. All the recursive solutions converge to the exact one except that with the initial value of deep-water solution. The solution with the initial value by Hunt converged much faster than the others. The recursive solutions may be obtained quickly and simply by a hand calculator. For the transformation of linear water waves in whole water depth, the use of the recursive solutions will yield more accurate analytical solutions than use of previously developed explicit solutions.
Three-Dimensional Flow Characteristics and Wave Height Distribution around Permeable Submerged Breakwaters; PART II - with Beach
Hur, Dong-Soo ; Lee, Woo-Dong ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 115~123
In the present study, a three dimensional hydrodynamic characteristics around the fully submerged dual breakwaters with a sand beach has been investigated numerically using a 3-D numerical scheme, which can determine the eddy viscosity with LES turbulence model and is able to consider wave-structure-seabed interaction in 3-dimensional wave field (LES-WASS-3D), recently developed by Hur and Lee (2007). Based on the numerical experiments, strong vortices can be generated fore and aft edges of the structures, and propagate lee sides. Thus relatively large circulation flows are occurred around submerged breakwaters. The 3-D flow hydrodynamic characteristics have been examined by mean flows and mean vortices for various x-y, x-z sections and y-z layers. Wave height distribution and wave set-up around and over submerged breakwaters, and breaking point migration toward shore side is discussed in detail.
Analyses on Local-Seasonal Variations of Erosional Properties of Cohesive Sediments in Keum Estuary
Yim, Shang Ho ; Ryu, Hong-Ryul ; Hwang, Kyu-Nam ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 125~135
The purpose of this study is to quantify the erosion parameters of cohesive sediments in Keum Estuary. This study also involves the examinations on the local/seasonal variation of them in Keum Estuary and on their spatial variation comparing with those of other sites. As erosional properties of cohesive sediments are in general influenced largely by the physico-chemical properties of cohesive sediments themselves, this study also involves the qualitative analyses on the impact by the physico-chemical properties. Erosion tests have been performed under the uniform bed condition using the Chonbuk annular flume and total 16 tests have been carried out with various bed densities and bottom shear stresses. Experimental results show that the critical shear stress for erosion varies in the range of
and the coefficient of erosion rate varies in the range of
, over the corresponding bulk-density range of
. While erosion parameters estimated for Keum estuary sediments are found to be remarkably different in quantity compared with those for cohesive sediments from other sites, their local/seasonal variabilities within Keum Estuary are found to be insignificant.
Evaluation of Efficiency of SVE from Lab-scale Model Tests and Numerical Analysis
Suk, Heejun ; Seo, Min Woo ; Ko, Kyung-Seok ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 137~147
Soil Vapor Extraction (SVE) has been extensively used to remove volatile organic compounds (VOCs) from the vadoze zone. In order to investigate the removal mechanism during SVE operation, laboratory modeling experiments were carried out and tailing effect could be observed in later stage of the experiment. Tailing effect means that removal rate of contaminants gets significantly to decrease in later stage of SVE operation. Also, mathematical model simulating the tailing effect was used, which considers rate-limited diffusion in a water film during mass transfer among gas, liquid, and solid phases. Measurement data obtained through the experiment was used as input data of the numerical analyses. Sensitivity analysis was performed to examine the effect of each parameter on required time to reach final target concentration. Finally, it was found that the concentration in the soil phase decreased significantly with a liquid and gas diffusion coefficient larger, actual path length shorter, and water saturation smaller.
Characteristics of the TCE removal in FeO/Fe(II) System
Sung, Dong Jun ; Lee, Yun Mo ; Choi, Won Ho ; Park, Joo yang ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 149~152
The reaction between iron oxide and ferrous iron is known to be the adsorption of ferrous iron onto the oxide surfaces that produces Fe(II)-Fe(III) (hydr)oxides and ferrous oxide oxidized to ferric ion which is the reducing agent of the target compounds. In our investigations on DS/S using ferrous modified steel slag, the results did not follow the trends. FeO and Fe(II), the major component of steel slag, were used to investigate the degradation of TCE. Degradation did not take place for the first and suddenly degraded after awhile. Degradation of TCE in this system was unexpected because Fe(II)-Fe(III) (hydr)oxides could not be produced in absence of ferric oxide. In this study, the characteristics of FeO/Fe(II) system as a reducing agent were observed through the degradation of TCE, measuring byproducts of TCE and the concentration of Fe(II) and Fe(III). Adsorption of ferrous ion on FeO was observed and the generation of byproducts of TCE showed the degradation of TCE by reduction in the system is obvious. However it did not correspond with the typical reducing mechanisms. Future research on this system needs to be continued to find out whether new species are generated or any unknown mineral oxides are produced in the system that acted in the degradation of TCE.
Discharge Characteristics of Indicator Microorganisms from Agricultural-Forestry Watersheds
Kim, Geonha ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 153~160
To estimate microbial contaminant loading discharged from diffuse sources, rainfall runoff of six rainfall events were monitored at three study watersheds of forestry and agricultural land use. Monitored indicator microorganism constituents were total coliform (TC), fecal coliform (FC), Escherichia coli (EC), and fecal streptococcus (FS). Soil loss during elevated flow rate caused higher suspended solid concentrations. Indicator microorganism concentrations were closely related with flow rate. TC event mean concentration (EMC) from unpolluted forestry was
, FC EMC was
, EC EMC was
, and FS EMC was
. From a watershed with agricultural-forestry land use, TC EMC was
, FC EMC was
, EC EMC was
, and FS EMC was
. Mixed land use of agricultural-forestry with bigger area, TC EMC was
, FC EMC was
, EC EMC was
, and FS EMC was
Evaluation of Bio-Chemical Restoration Index at the Creation Site of Ecological Environmental Zone in Coastal Area
Lee, In-Cheol ; Yi, Byung Ho ; Park, So Young ; Ryu, Cheong Ro ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 1B, 2008, Pages 161~168
The ecological environmental zones in coastal area, like tidal flat and salt marsh, were gradually decreased due to large scale of coastal development projects, reclamation and so on. Therefore, the development of artificial tidal flat and salt marsh has been emphasized in coastal area as mitigation concept and studies on related this background has performed. But studies on the quantitative evaluation for degree of restoration were insufficient. In this paper, as a fundamental study for evaluation of restoration on the creation of ecological environmental zones in coastal area, it was conducted that the monitoring and experiment for bio-chemical factors (bio-diversity, population and biomass of macro-benthos, survival ratio of reed, the number of heterotrophic bacteria and physico-chemical characteristics such as COD, IL, TN, TP and pH) using a in-situ pilot plant of tidal flat (Zone. P1) and salt marsh (Zone. P2), which was distinguished by content of dredged soil, in Jinudo, Nakdong estuary. From results of this study, the restoration index (RI), for evaluation concerning degree of restoration on the creation of ecological environmental zones in coastal area, was suggested and quantitative evaluation was performed using a restoration index (RI).