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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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Journal DOI :
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
On Proper Variograms of Daily Rainfall Data
Park, Minkyu ; Park, Changyeol ; Shin, Key-Il ; Yoo, Chulsang ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 525~532
Kriging is widely applied to dealing with the spatial distribution of rainfall, however its prediction results are different according to the selection of variogram type. This study investigated adequate variogram for daily rainfall. The comparative results show that kriging prediction with covariates is better than that without covariates. The Mat
rn correlation function, which is the most general type variogram, is recommended if adequate variogram is difficult to determine.
Conveyance Analysis of Downstream of the Soyang Reservoir Considering the Influence of Vegetation
Noh, Joonwoo ; Shin, Hyunho ; Kim, Hojoon ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 533~540
Recently management of vegetation distributed in the watercourse is very important not only for safety but also for river restoration. In general, vegetations in the watercourse increase hydraulic resistance and accordingly decrease conveyance capacity which may yield levee overflow. This paper simulates water level rise using 1D and 2D hydro dynamic model to check the possibility of overflow in downstream of the Soyang Reservoir by assigning different roughness coefficient corresponding to different types of vegetation. In this study, 3 different vegetation types of tree, shrub, and main channel were considered and corresponding Manning's roughness coefficient n was assigned based on the vegetation map generated from the site investigation. As results, the water level raised about 0.1 to 0.7 m comparing with the case without considering vegetation and a proper measurements is necessary where overflow occurs due to low level levee.
The study of Application of Drought Index Using Measured Soil Moisture at KoFlux Tower
Kim, Sooyoung ; Jo, Hwan Bum ; Lee, Seung Oh ; Choi, Minha ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 541~549
While the number of rainy days is decreasing, the mean annual precipitation is increasing due to abnormal climate changes caused by the global warming in Korea. Owing to the biased-concentration of rainfall during specific short terms, not only flood but also drought becomes more and more serious. From the literature, it is easily found that previous studies about flood have been intensively conducted. However, previous studies about drought have been performed rarely. This study conducted the comparison between two representative drought indexes calculated from soil moisture and precipitation. Study area was Haenam-gun, Jeollanam-do in Korea. Soil Moisture Index(SMI) was calculated from soil moisture data while the Standardized Precipitation Index(SPI) and the Palmer Drought Severity Index(PDSI) were calculated from meteorological data. All monthly data utilized in this study were observed at the KoFlux Tower. After the comparative analysis, three indexes showed similar tendency. Therefore, it is thought that the drought index using soil moisture measured at the KoFlux Tower is reasonable, which is because the soil moisture is immediately affected by all the meteorological factors.
The hydrologic flux of SS, TN and TP in Nakdong River Basin
Lee, Ayeon ; Choi, Daegyu ; Kim, Tae-Woong ; Kim, Sangdan ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 551~560
This study presents the export of constituent transport loads through a river system. The proposed constituent transport load estimating procedure can be operated with the on-going Korean TMDL monitoring system. This study firstly discusses the use of a hydrologic simulation model (TANK) to estimate stream-flow for the 40 sub-catchments. Model parameters are estimated from 8-days intervals flow data which has been monitored by NIER since 2004. Constituent transport loads are estimated with the 7-parameter log linear model whose parameters are estimated by the minimum variance unbiased estimator. Results from Nakdong river basin reveals that the proposed procedure provides satisfactory TN, TP and SS transport load estimates. As an application, a representative load duration curve is derived to represent the overall hydrologic flux of TN, TP and SS at Nakdong river basin.
Application of SAD Curves in Assessing Climate-change Impacts on Spatio-temporal Characteristics of Extreme Drought Events
Kim, Hosung ; Park, Jinhyeog ; Yoon, Jaeyoung ; Kim, Sangdan ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 561~569
In this study, the impact of climate change on extreme drought events is investigated by comparing drought severity-area-duration curves under present and future climate. The depth-area-duration analysis for characterizing an extreme precipitation event provides a basis for analysing drought events when storm depth is replaced by an appropriate measure of drought severity. In our climate-change impact experiments, the future monthly precipitation time series is based on a KMA regional climate model which has a
spatial resolution, and the drought severity is computed using the standardized precipitation index. As a result, agricultural drought risk is likely to increase especially in short duration, while hydrologic drought risk will greatly increase in all durations. Such results indicate that a climate change vulnerability assessment for present water resources supply system is urgent.
Optimization for Roughness Coefficient of River in Korea - Review of Application and Han River Project Water Elevation -
Kim, Jooyoung ; Lee, Jong-Kyu ; Ahn, Jong-Seo ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 571~578
Manning's roughness coefficients were reevaluated for the computation of river flow of the Han River, the Nakdong River and the Geum River. The roughness coefficients were estimated by two methods. One is based on the assumption that roughness is primarily a function of grain diameter and the other is based on the findings that roughness may vary significantly with the flow discharge. The roughness coefficients adopted in each river improvement master plan have been compared with those obtained using the FLDWAV in this study, and their applicabilities have been reviewed, using the FLDWAV and HEC-RAS models. The design flood water levels computed by the abovementioned models with the roughness coefficients proposed in this study have shown good agreement with the measurements of time variation. The roughness coefficients computed using the FLDWAV model showed nearly no close correlation with the various hydraulic characteristic factors, such as grain size and river depth, etc.. Finally the design flood water levels and levee safety about the downstream part from the Paldang Dam of the Han River has been reviewed using HEC-2 model with roughness coefficients of this study and the results indicated that some parts of the existing levees were short of safety.
Realtime Streamflow Prediction using Quantitative Precipitation Model Output
Kang, Boosik ; Moon, Sujin ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 579~587
The mid-range streamflow forecast was performed using NWP(Numerical Weather Prediction) provided by KMA. The NWP consists of RDAPS for 48-hour forecast and GDAPS for 240-hour forecast. To enhance the accuracy of the NWP, QPM to downscale the original NWP and Quantile Mapping to adjust the systematic biases were applied to the original NWP output. The applicability of the suggested streamflow prediction system which was verified in Geum River basin. In the system, the streamflow simulation was computed through the long-term continuous SSARR model with the rainfall prediction input transform to the format required by SSARR. The RQPM of the 2-day rainfall prediction results for the period of Jan. 1~Jun. 20, 2006, showed reasonable predictability that the total RQPM precipitation amounts to 89.7% of the observed precipitation. The streamflow forecast associated with 2-day RQPM followed the observed hydrograph pattern with high accuracy even though there occurred missing forecast and false alarm in some rainfall events. However, predictability decrease in downstream station, e.g. Gyuam was found because of the difficulties in parameter calibration of rainfall-runoff model for controlled streamflow and reliability deduction of rating curve at gauge station with large cross section area. The 10-day precipitation prediction using GQPM shows significantly underestimation for the peak and total amounts, which affects streamflow prediction clearly. The improvement of GDAPS forecast using post-processing seems to have limitation and there needs efforts of stabilization or reform for the original NWP.
Flow Characteristics and Riverbed Change Simulation on Bridge-intensive Section
Cho, Hong Je ; Jeon, Woo Yeol ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 589~598
When the hydraulic structures, such as bridge and weir, are consecutively installed to a short section of a river with complicated cross section, analyzing the flow characteristics and the riverbed change modality of the river is very important. In the 250 m section of the Taehwa river near the Samho-bridge, which passes through Ulsan city, three bridges has been installed, and the tributary water is flowing into both up and downstream of the section. Due to these factors, when the flood occurs, the cross section of the river changes vastly by the water level change and scour. Even so, due to the fact that the Samho-bridge divides the section into two parts, the national river and the regional river, each part is being analyzed separately by the onedimensional model. In this study, the flow characteristics due to the bridge concentration and the tributary water inflow were jointly analyzed for both up and downstream by using the one-dimensional HEC-RAS model and the two-dimensional SMS model, such as RMA2. The riverbed change modality of the section was also investigated by using the SED2D model. The results showed that the water level difference between the HEC-RAS and RMA2 was 0.87 m when applied to the three consecutive bridges. The riverbed change simulation using SED2D showed that the maximum scour was 0.231 m and it occurred at the Samho-bridge, which located in the middle and has short pier distance. In conclusion, when planning the river maintenance for the regions with concentrated bridges or the sections with severe changes in cross-section and flow, estimating the flood elevation by two-dimensional model and establishing countermeasures for the scouring of the bridge are required. In addition, an integrated analysis on both the national river and the regional river is necessary.
Drought Frequency Analysis Using Cluster Analysis and Bivariate Probability Distribution
Yoo, Ji Young ; Kim, Tae-Woong ; Kim, Sangdan ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 599~606
Due to the short period of precipitation data in Korea, the uncertainty of drought analysis is inevitable from a point frequency analysis. So it is desired to introduce a regional drought frequency analysis. This study first extracted drought characteristics from 3-month and 12-month moving average rainfalls which represent short and long-term droughts, respectively. Then, the homogeneous regions were distinguished by performing a principal component analysis and cluster analysis. The Korean peninsula was classified into five regions based on drought characteristics. Finally, this study applied the bivariate frequency analysis using a kernel density function to quantify the regionalized drought characteristics. Based on the bivariate drought frequency curves, the drought severities of five regions were evaluated for durations of 2, 5, 10, and 20 months, and return periods of 5, 10, 20, 50, and 100 years. As a result, the largest severity of drought was occurred in the Lower Geum River basin, in the Youngsan River basin, and over in the southern coast of Korea.
Development and Application of Depth-integrated 2-D Numerical Model for the Simulation of Hydraulic Characteristics in Vegetated Open-Channels
Kim, Tae Beom ; Bae, Hea Deuk ; Choi, Sung-Uk ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 607~615
Vegetation drag tends to raise water level by retarding the flow. Previous studies have focussed on either the vertical structure modeling or the one-dimensional modeling, which can hardly be used to simulate the vegetative streams in practical engineering. Therefore, this paper presents a two-dimensional numerical model based on the depth-averaged flow equations. Vegetation drags are reflected in the flow equations, assuming non-flexible rigid cylinders. For validations, flow properties measured in both rectangular and compound channels are compared with simulated data, showing good agreement. Then, the model is applied to a reach in the Han River and the impact of floodplain vegetation on the flow is investigated.
Assessment of Wind Energy Potential around Jeju Coastal Area
Kim, Nam Hyeong ; Jin, Jung Woon ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6B, 2010, Pages 617~625
The selection of a site where strong wind blows is important to increase effectively the electricity of wind power in proportion to the cube of the wind speed. It is advisable to establish the wind turbine in the coastal area with strong wind speed rather than in the inland. And the development of offshore wind energy is expected to solve the noise problem that is one of the important weaknesses in the wind turbine. In the process of the development business of wind energy, knowing forehead the wind power possibility in any area is one of the essential factors to choose the most optimum site of wind power. In this paper, the potential of wind power around JeJu coastal area is examined by using the wind data that Korea Meteorological Administration has surveyed for 10 years in 14 observation points. Wind speed data is revised to wind speed in 80 meters assuming installation height of the wind turbine, and wind power density and annual wind energy are also calculated. And annual electricity generation and percent of energy efficiency in all the observation points are estimated by using the information about 3,000 KW wind turbine.