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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 30, Issue 6D - Dec 2010
Volume 30, Issue 6C - Dec 2010
Volume 30, Issue 6B - Dec 2010
Volume 30, Issue 6A - Dec 2010
Volume 30, Issue 5D - Oct 2010
Volume 30, Issue 5C - Oct 2010
Volume 30, Issue 5B - Oct 2010
Volume 30, Issue 5A - Oct 2010
Volume 30, Issue 4D - Aug 2010
Volume 30, Issue 4C - Aug 2010
Volume 30, Issue 4B - Aug 2010
Volume 30, Issue 4A - Aug 2010
Volume 30, Issue 3D - Jun 2010
Volume 30, Issue 3C - Jun 2010
Volume 30, Issue 3B - Jun 2010
Volume 30, Issue 3A - Jun 2010
Volume 30, Issue 2D - Apr 2010
Volume 30, Issue 2C - Apr 2010
Volume 30, Issue 2B - Apr 2010
Volume 30, Issue 2A - Apr 2010
Volume 30, Issue 1D - Feb 2010
Volume 30, Issue 1C - Feb 2010
Volume 30, Issue 1B - Feb 2010
Volume 30, Issue 1A - Feb 2010
Selecting the target year
Estimation of Spatial Evapotranspiration Using satellite images and SEBAL Model
Ha, Rim ; Shin, Hyung-Jin ; Lee, Mi-Seon ; Kim, Seong-Joon ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 233~242
SEBAL (Surface Energy Balance Algorithm for Land) developed by Bastiaanssen (1995) is an image-processing model comprisedof twenty-five sub models that calculates spatial evapotranspiration (ET) and other energy exchanges at the surface. SEBAL uses image data from Landsat or other satellites measuring thermal infrared radiation, visible and near infrared. In this study, the model was applied to Gyeongancheon watershed, the main tributary of Han river Basin. ET was computed on apixel-by-pixel basis from an energy balance using 4 years (2001-2004) Landsat and MODIS images. The scale effect between Landsat (30 m) and MODIS (1 km) was evaluated. The results both from Landsat and MODIS were compared with FAO Penman-Monteith ET. The absolute errors between satellite ETs and Penman-Monteith ET were within 12%. The spatial and temporal characteristics of ET distribution within the watershed were also analyzed.
Analysis of the Spatial Distribution of Pan Evaporation Trends
Rim, Chang-Soo ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 243~255
The spatial distribution of pan evaporation and pan evaporation trends have been studied. In this study, pan evaporation data from 1973 to 1990 for 56 climatological stations were analyzed. In addition to annual average daily pan evaporation, monthly average daily pan evaporation in April, July, October and January were analyzed, considering seasonal effect. The study results indicate that in case of annual average daily pan evaporation, 38 stations out of 56 stations show decreasing trend. In case of average daily pan evaporation in January, 33 stations show decreasing trend. In April, 38 stations show increasing trend. In July, 47 stations show decreasing trend. In October, 35 stations show increasing trend. Therefore, on the whole, pan evaporation tended to decrease in January, July, and annual basis. On the other hand, pan evaporation tended to increase in April and October. Furthermore, pan evaporation trend in each individual region shows also different trend even though the region is located nearby, indicating that there are geographical and topographical effects on pan evaporation trend. Pan evaporation data and climatic data from 1973 to 2006 for 11 climatological stations were used for trend analysis. Climatic variables such as temperature, relative humidity and wind speed show same or opposite trend direction compared with pan evaporation in annual or monthly basis. Annual and monthly solar radiation trends show the same direction compared with pan evaporation; however, annual and monthly precipitation trends show the opposite direction compared with pan evaporation.
Evaluation of Flood Events Considering Correlation between Flood Event Attributes
Lee, Jeong Ho ; Yoo, Ji Young ; Kim, Tae-Woong ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 257~267
A flood event can be characterized by three attributes such as peak discharge, total flood volume, and flood duration, which are correlated each other. However, the amount of peak discharge is only used to evaluate the flood events for the hydrological plan and design. The univariate analysis has a limitation in describing the complex probability behavior of flood events. Thus, the univariate analysis cannot derive satisfying results in flood frequency analysis. This study proposed bivariate flood frequency analysis methods for evaluating flood events considering correlations among attributes of flood events. Parametric distributions such as Gumbel mixed model and bivariate gamma distribution, and a non-parametric model using a bivariate kernel function were introduced in this study. A time series of annual flood events were extracted from observations of inflow to the Soyang River Dam and the Daechung Dam, respectively. The joint probability distributions and return periods were derived from the relationship between the amount of peak discharge and the total volume of flood runoff. Applicabilities of bivariate flood frequency analysis were examined by comparing the return period acquired from the proposed bivariate analyses and the conventional univariate analysis.
Estimation of Design Rainfalls Considering BCM2 Simulation Results
Lee, Chang Hwan ; Kim, Tae-Woong ; Kyoung, Minsoo ; Kim, Hung Soo ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 269~276
Climatic disasters are globally soaring due to recent acceleration of global warming. Especially the occurrence frequency of heavy rainfalls is increasing since the rainfall intensity is increasing due to the change of rainfall pattern, This study proposed the non-stationary frequency analysis for estimating design rainfalls in a design target year, considering the change of rainfall pattern through the climatic change scenario. The annual rainfalls, which are regionally downscaled from the BCM2 (A2 scenario) and NCEP data using a K-NN method, were used to estimate the parameters of a probability distribution in a design target year, based on the relationship between annual mean rainfalls and distribution parameters. A Gumbel distribution with a probability weighted method was used in this study. Seoul rainfall data, which are the longest observations in Korea, were used to verified the proposed method. Then, rainfall data at 7 stations, which have statistical trends in observations in 2006, were used to estimate the design rainfalls in 2020. The results indicated that the regional annual rainfalls, which were estimated through the climate change scenario, significantly affect on the design rainfalls in future.
Coupled Operation of the Lake Youngsan, Yeongam and Kumho for the Flood Stage Control in the Downstream of the Youngsan River
Kim, Dae Geun ; Kim, Dong Ok ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 277~284
To examine how the width of connecting channels, the width of the Kumho lock gate, and the opening/shutting criteria of the Yeongam connecting channel lock gate affect the flood stage of Lake Yeongsan, Lake Yeongam, and Lake Kumho, located in the lower reaches of the Yeongsan River, unsteady flood routing was performed by connecting the three lakes into a single interlinked system. The coupled operation of the three lakes was found to have little effect when the widths of the lock gates and the Yeongam and Kumho connecting channels are set at the current level. The most effective way to lower the water level in Lake Yeongsan was to widen the Yeongam connecting channel, but this caused the water level in Lake Yeongam to rise. To lower the increased water level in Lake Yeongam by utilizing the water storage capacity of Lake Kumho, it was necessary to widen both the Kumho lock gate and the Kumho connecting channel. It was found that the optimum opening/shutting criterion for the Yeongam connecting channel lock gate is approximately EL.(+)0.8 m under the simulated conditions used in this study and the criterion allows of maximal lowering of the water levels in Lake Yeongam and Lake Kumho while maintaining a near-constant water level in Lake Yeongsan.
Spatio-temporal Variability of Soil Moisture within Remote Sensing Footprints in Semi-arid Area
Hwang, Kyotaek ; Cho, Hun Sik ; Lee, Seung Oh ; Choi, Minha ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 285~293
Soil moisture is a key factor to control the exchange of water and energy between the surface and the atmosphere. In recent, many researches for spatial and temporal variability analyses of soil moisture have been conducted. In this study, we analyzed the spatio-temporal variability of soil moisture in Walnut Gulch Experimental Watershed, Arizona, U.S. during the Soil Moisture Experiment 2004 (SMEX04). The spatio-temporal variability analyses were performed to understand sensitivity of five observation sites with precipitation and relationship between mean soil moisture, and its standard deviation and coefficient of variation at the sites, respectively. It was identified that log-normal distribution was superior to replicate soil moisture spatial patterns. In addition, precipitation was identified as a key physical factor to understand spatio-temporal variability of soil moisure based on the temporal stability analysis. Based on current results, higher spatial variability was also observed which was agreed with the results of previous studies. The results from this study should be essential for improvement of the remotely sensed soil moisture retrieval algorithm.
Analysis of Spatial-temporal Variability of NOAA/AVHRR NDVI in Korea
Kim, Gwangseob ; Kim, Jong Pil ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 295~303
The variability of vegetation is strongly related to the variability of hydrometeorological factors such as precipitation, temperature, runoff and so on. Analysis of the variability of vegetation will aid to understand the regional impact of climate change. Thus we analyzed the spatial-temporal variability of NOAA(National Oceanic and Atmospheric Administration)/AVHRR(Advanced Very High Resolution Radiometer) NDVI(Normalized Difference Vegetation Index). In the results from Mann-Kendall test, there is no significant linear trend of annual NDVI from 1982 to 2006 in the most area except the downward trend on the significance level 90% in the Guem-river basin area. In addition, using EOF(Empirical Orthogonal Function) analysis, the variability of NDVI in the region of higher latitude and altitude is higher than that in the other region since the spatial variability of NDVI follows the latitudinal gradient. Also we could get higher NDVI in June, July, August and September. We had the highest NDVI in Han-river basin area and the lowest in Je-Ju island.
Stable Channel Analysis and Design for the Abandoned Channel Restoration Site of Cheongmi Stream using Regime Theory
Ji, Un ; Julien, Pierre Y. ; Kang, Joon Gu ; Yeo, Hong Koo ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 305~313
River restoration or rehabilitation should be conducted in a way to maximize the channel stability with natural river configuration close to the equilibrium condition considering divers aspects of fluvial hydraulics, erosion and sedimentation, fluvial geomorphology, and ecological environment and to minimize the maintenance work. Therefore, the channel stability evaluation for present condition based on the equilibrium channel concept should be preceded for the river restoration project. Methods for equilibrium channel theory have generally been developed following either analytical regime theory or empirical regime theory. The main purpose of this paper is to evaluate the stability of present channel condition for the section of abandoned channel restoration in Cheongmi Stream using the Stable channel Analytical Model (SAM) and equilibrium hydraulic geometry equations. The results of analytical and empirical regime theories should provide fundamental and essential information to design the stable channel geometry. As a calculation result of Copeland's method for the study reach, the equilibrium channel has a narrower channel width, deeper water depth, and more gentle slope than the present channel geometry. As results of equilibrium hydraulic geometry equations, predicted equilibrium widths are less than the channel width in the field. It is represented that the current bed slope must be gentle to reach the equilibrium condition according to the results of Julien and Wargadalam method.
Development of a Design Chart for the Initial Design Stage of Very Large Floating Structures
Zi, Goangseup ; Kim, Jin Gyun ; Lee, Seung Oh ; Lee, Phill-Seung ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 315~324
We developed a design chart for very large floating structures through intensive hydroelastic analysis. Using this chart, one can predict the hydroelastic response of very large floating structures preliminarily at design stage without the cost-demanding hydroelastic analysis. This paper presents two new design charts based on the theory of VLFS. The purpose of the first design chart is to determine RAOs of the maximum longitudinal stress of VLFS considering properties of waves and structures. The design chart I can be applied to any sizes of VLFS in same aspect ratios and dimensionless stiffness parameters. The second design chart is developed to take into account the actual wave condition by using the Bretschneider spectrum with Beaufort sea state.
A Study on Beach Stabilization by Laying Drainage Layer
Hur, Dong-Soo ; Lee, Woo-Dong ; Jeon, Ho-Sung ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 3B, 2010, Pages 325~335
The aim of this study is to survey the effects of laying drainage layer in sandy beach on beach stabilization. At first, the numerical model developed by Hur and Lee (2007), which is able to consider the flow through a porous medium with inertia, laminar and turbulent resistance terms, i.e. simulate directly WAve Structure Seabed/Sandy beach interaction and can determine the eddy viscosity with LES turbulent model in 3-D wave field (LES-WASS-3D), is validated by comparing with existing experimental data. And then, numerical simulation is carried out to examine the characteristics of wave-sandy beach interaction for a beach with/without drainage layer. From the numerical results, it is shown that mean ground-water level around a foreshore decreases and offshore-ward flow over a seabed reduces in case of a beach with drainage layer. Moreover, the effects of cross profile of drainage layer and incident wave condition on mean ground-water level around a foreshore are also discussed as well the distribution of wave setup around the foreshore.