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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 31, Issue 6D - Dec 2011
Volume 31, Issue 6C - Dec 2011
Volume 31, Issue 6B - Dec 2011
Volume 31, Issue 6A - Dec 2011
Volume 31, Issue 5D - Oct 2011
Volume 31, Issue 5C - Oct 2011
Volume 31, Issue 5B - Oct 2011
Volume 31, Issue 5A - Oct 2011
Volume 31, Issue 4D - Aug 2011
Volume 31, Issue 4C - Aug 2011
Volume 31, Issue 4B - Aug 2011
Volume 31, Issue 4A - Aug 2011
Volume 31, Issue 3D - Jun 2011
Volume 31, Issue 3C - Jun 2011
Volume 31, Issue 3B - Jun 2011
Volume 31, Issue 3A - Jun 2011
Volume 31, Issue 2D - Apr 2011
Volume 31, Issue 2C - Apr 2011
Volume 31, Issue 2B - Apr 2011
Volume 31, Issue 2A - Apr 2011
Volume 31, Issue 1D - Feb 2011
Volume 31, Issue 1C - Feb 2011
Volume 31, Issue 1B - Feb 2011
Volume 31, Issue 1A - Feb 2011
Selecting the target year
Evaluation of DEM-based Channel Network Delineation Methods on Watershed Drainage System
Lee, Gi Ha ; Yoon, Eui Hyeok ; Kim, Joo Cheol ; Jung, Kwan Sue ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 1~11
Channel network delineation from DEM (Digital Elevation Model) is a fundamental pre-process for hydrologic model application since it determines the drainage system in a watershed. This study aims to propose an effective and efficient channel network delineation process and assess the effects of DEM-based channel networks on the watershed drainage system. For these objectives, we applied two methods to generate the channel networks of the Jinan-cheon catchment with
from the 20 m resolution DEM: a widely-used area-threshold method and a slope-area threshold method based on the relationship between contributing areas and local slopes. The results showed that the area-threshold method led to unreliable drainage system, which did not satisfy geomorphological laws with respect to drainage density and source area representation whereas the slope-area threshold method provided acceptable results under the geomorphological laws. Our suggestions in this study can give valuable pre-processing information in DEM-based hydrologic modeling.
Analysis on Spatio-Temporal Pattern and Regionalization of Extreme Rainfall Data
Lee, Jeong-Ju ; Kwon, Hyun-Han ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 13~20
The spatio-temporal pattern in precipitation is a significant element in defining characteristics of precipitation. In this study, a new scheme on regionalization utilizing temporal information was introduced on the basis of existing approaches that is mainly based on simple moments of data and geographical information. Given the identified spatio-temporal pattern, this study was extended to characterize regional pattern of annual maximum rainfall over Korea. We have used circular statistics to characterize the temporal distribution on the precipitation, and the circular statistics allow us to effectively assess changes in timing of the extreme rainfall in detail. In this study, a modified K-means method was incorporated with derived temporal characteristics of extreme rainfall in order to better characterize hydrologic pattern for regional frequency analysis. The extreme rainfall was reasonably separated into five categories that considered most attributes in both quantitative and temporal changes in extremes. The results showed that the proposed approach is a promising approach for regionalization in term of physical understanding of extreme rainfall.
Study of Stochastic Techniques for Runoff Forecasting Accuracy in Gongju basin
Ahn, Jung Min ; Hur, Young Teck ; Hwang, Man Ha ; Cheon, Geun Ho ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 21~27
When execute runoff forecasting, can not remove perfectly uncertainty of forecasting results. But, reduce uncertainty by various techniques analysis. This study applied various forecasting techniques for runoff prediction's accuracy elevation in Gongju basin. statics techniques is ESP, Period Average & Moving average, Exponential Smoothing, Winters, Auto regressive moving average process. Authoritativeness estimation with results of runoff forecasting by each techniques used MAE (Mean Absolute Error), RMSE (Root Mean Squared Error), RRMSE (Relative Root Mean Squared Error), Mean Absolute Percentage Error (MAPE), TIC (Theil Inequality Coefficient). Result that use MAE, RMSE, RRMSE, MAPE, TIC and confirm improvement effect of runoff forecasting, ESP techniques than the others displayed the best result.
Characteristics of Greenup and Senescence for Evapotranspiration in Gyeongan Watershed Using Landsat Imagery
Choi, Minha ; Hwang, Kyotaek ; Kim, Tae-Woong ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 29~36
Evapotranspiration (ET) from the various surfaces needs to be understood because it is a crucial hydrological factor to grasp interaction between the land surface and the atmosphere. A traditional way of estimating it, which is calculating it empirically using lysimeter and pan evaporation observations, has a limitation that the measurements represent only point values. However, these measurements cannot describe ET because it is easily affected by outer circumstances. Thus, remote sensing technology was applied to estimate spatial distribution of ET. In this study, we estimated major components of energy balance method (i.e. net radiation flux, soil heat flux, sensible heat flux, and latent heat flux) and ET as a map using Mapping Evapo-Transpiration with Internalized Calibration (METRIC) satellite-based image processing model. This model was run using Landsat imagery of Gyeongan watershed in Korea on Feb 1, 2003 and Sep 13, 2006. Basic statistical analyses were also conducted. The estimated mean daily ETs had respectively 22% and 11% of errors with pan evaporation data acquired from the Suwon Weather Station. This result represented similar distribution compared with previous studies and confirmed that the METRIC algorithm had high reliability in the watershed. In addition, ET distribution of each land use type was separately examined. As a result, it was identified that vegetation density had dominant impacts on distribution of ET. Seasonally, ET in a growing season represented significantly higher than in a dormant season due to more active transpiration. The ET maps will be useful to analyze how ET behaves along with the circumstantial conditions; land cover classification, vegetation density, elevation, topography.
Analysis of Noise Influence on a Chaotic Series and Application of Filtering Techniques
Choi, Min Ho ; Lee, Eun Tae ; Kim, Hung Soo ; Kim, Soo Jun ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 37~45
We studied noise influence on nonlinear chaotic system by using Logistic data series which is known as a typical nonlinear chaotic system. We regenerated Logistic data series by the method of adding noise according to noise level. And, we performed some analyses such as phase space reconstruction, correlation dimension, BDS statistics, and DVS Algorithms which are known as the methods of nonlinear deterministic or chaotic analysis. If we see the results of analysis, the characteristics of data series are gradually changed from nonlinear chaotic data series to random stochastic data series according to increasing noise level. We applied Low Pass Filter (LPF) and Kalman Filter techniques for the investigation of removing effect of the added noise to data series. Typical nonparametric method cannot distinguish nonlinear random series but the BDS statistic can distinguish the nonlinear randomness of the time series. Therefore this study used the BDS statistic which is well known as nonlinear statistical method for the investigation of randomness of time series for the effect of removing noise of data series. We found that Kalman filter is better method to remove the noise of chaotic data series even for high noise level.
Suggestion of Synthetic Unit Hydrograph Method Considering Hydrodynamic Characteristic on the Basin
Kim, Joo Cheol ; Choi, Yong Joon ; Jeong, Dong Kug ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 47~55
This study suggests new synthetic unit hydrograph method considering hydrodynamic characteristic on the basin. The suggested method based on width function GIUH, and the procedure is summarized as follows; 1) Draw up a travel distance distribution map (width function) which is raster of length between from center of individual cells to the outlet by GIS. 2) Calculation of travel time distribution map (rescaled width function) by hydrodynamic parameters and travel distance distribution map. 3) Derivation of IUH and Duration UH from rescaled width function. 4) Comparison of shape of UH between suggested method and existing synthetic unit hydrograph methods. The target basins are selected Ipyeong and Tanbu subwatershed in the Bocheong Basin. The target basins are similar scale (watershed area), but different drainage structure (drainage density et al.). Therefore we anticipate that there are different hydrologic response functions because different hydrodynamic characteristics. As a result of derivation of UH, existing synthetic unit hydrograph methods are similar shape of UHs about Ipyeong and Tanbu watersheds, but the suggested method is different shape of ones. As a result of application to observed data, the peak discharge by suggested method is similar to existing synthetic unit hydrograph methods, but the peak time is well correspondence between those. Henceforth, if the suggested method combines with the rational velocity estimation method, it is useful method for synthetic of UH in ungauged watershed.
An Experimental Study to Estimate the Energy Change by Side Weir
Cho, Hong Je ; Yoon, Yeong Bae ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 57~62
The river disaster caused by installation of hydraulic structures on the river gives varieties to flowing water stream, tractive force and so on. In this study, the changes of tractive force and energy from the side weir installation for the purpose of flood control was analyzed through laboratory experiment. The experiments of the pre and after-installation have been performed under conditions that waterway is trapezoidal shape, waterway slope ranges are from 0.1 to 1.0 percentage, and flow rates are 25 l/sec. As results, the specific energy ratio increases in the higher slope and at a certain point, larger specific energy ratio showed than 1 in the 1.0% slope. The tractive force ratio decreases in higher slope and the sections that tractive force ratio appeared higher than 1 are more widespread in the direction of downstream. And calculated tractive force is about 1.3.
An Estimation of discharge Coefficient for Broad Crested Side Weir
Yoon, Yeong Bae ; Cho, Hong Je ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 63~70
To install the side weirs in inlet of washland construction, it is necessary to calculate more accurately the discharges over side weir. In this study, the hydraulic experiments were performed in broad crested side weirs that installed trapezoidal channel and that considered more applicable to the actual river. Upstream Froude number in the main channel and weir height, length, width and slope of main channel were considerd for estimation of discharge coefficient of broad crested side weir. Experimental results show that the discharge coefficient of broad crested side weir depend on, and. New estimated equation for the discharge coefficient are suggested through the multiple regression analysis and its applicability is confirmed by comparing estimated and measured discharges over side weirs.
Analysis of Saltwater Intrusion Effects into Coastal Aquifers in Korea considering Climate Change Effects
Yang, Jeong-Seok ; Nam, Jae-Joon ; Park, In-Bo ; Kim, Sangdan ;
Journal of The Korean Society of Civil Engineers, volume 31, issue 1B, 2011, Pages 71~85
Saltwater intrusion effects of coastal aquifers in Korea peninsula were analyzed through trend analysis with groundwater level, seawater level, seawater temperature, and electrical resistivity(EC) data sets. Groundwater level and EC data sets from 27 coastal regions were collected and analyzed. Groundwater level was stable for all the regions however EC data showed stable or changing trends (9 increasing, 10 stable, and 8 decreasing regions). Seawater temperature was collected and analyzed for 14 regions and they are increasing for most regions (12 increasing and 2 stable regions). Seawater level was also collected and analyzed for 24 regions and is rising for most regions (18 rising, 3 stable, and 3 falling regions). Especially, west cost regions have stronger increasing tendencies of seawater level, seawater temperature, and EC than eastern and southern coastal regions. Therefore the saltwater intrusion problem can be serious for west cost regions in Korea peninsula and it is necessary to establish a plan to minimize the damages from saltwater intrusion.