• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.82-92
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• 2021

Nakdong technique is an unfamiliar scorching treatment using an iron heated in a kiln over 1000℃. It is a typical convention in Asian countries to treat Nakdong on the surface of paulownia species. The scorching treatment changes the surface characteristics as well as the color of the wood. This study focused on the effects of functional features such as water resistance, anti-mold, anti-termite, and sound improvement because this treatment is usually used on paulownia wood-bodied musical instruments surface. It took 28'57" for Nakdong-iron treated surface to absorb a droplet of water. The absorbance time of iron treated surface was longer than that of torch treated one. There was no noticeable effect on the anti-mold test. On the anti-termite test, there was nearly 3% more mean mass loss on the torch samples than controlled and iron treated ones. In examining the sound radiation coefficient before and after Nakdong treatment, the Nakdong-iron treated surface showed an increase in the average value of 1.2 m4/kg s, which means that it has sound quality improvement. Through this research, the Nakdong technique results are expected to be used as basic-data for further research and give a practical idea for using the traditional treatment method on the wood surface.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.389-402
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• 2014

In this study, simulation technique with multi-dimensional model(EFDC), coupled with COSFIM and FLDWAV, has been applied to the upstream and downstream of weirs for hydraulic characteristics analysis through development of system and was performed for 8 multi-function weirs on Nakdong river using developed system. COSFIM, FLDWAV and EFDC can utilize suitable model in situation because they have pros and cons according to practical use purpose. Developed technique can offers spatial and grid unit information as well as line and section unit information from 1-D modeling. It is considered that the coupling simulation technique can provide useful hydraulic information for river management and treatment.

• Journal of Korea Water Resources Association
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• v.31 no.4
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• pp.483-490
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• 1998

The possibility of water transfer from Han river basin to Nakdong river basin by connecting them is studied as an alternative to solve water shortage problem in Nakdong river basin. After estimating the amount of water shortage from Nakdong river basin, the amount of water surplus from Han river basin is estimated by using simulation and optimization techniques. HEC-5 is used to study small to medium size reservoirs as a simulation technique and dynamic programming is used to study multi-purpose reserviors as an optimization technique. Also, the cost of the interbasin water transfer from Han river basin to Nakdong river basin is also compared with that of constructing new reserviors in Nakdong river basin. If new reservoirs are constructed in Nakdong river basin as planned, water supply can satisfy various water demands until 2021 without the interbasin water transfer. In economic point of view, constructing new reserviors has an advantage over the interbasin water transfer.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.63-74
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• 2018

As part of the Four Major Rivers Restoration Project, multifunctional weirs have been constructed in the rivers and operated for river-level management. As the weirs play a role in draining water from tributaries, the aim of this study was to determine the influence of the weirs on the water level of the Nam River, which is one of the Nakdong River's tributaries. Self-organizing maps (SOMs) and a locally weighted scatterplot smoothing (LOWESS) technique were applied to analyze the patterns and trends of water level and quality of the Nakdong River, considering the operation of the Changnyeong-Haman weir, which is located where the Nam River flows into the Nakdong River. The software program HEC-RAS was used to find the boundary points where the water is well drained. Per the study results at the monitoring points ranging between the junction of the two rivers and 17.5 km upstream toward the Nam River, the multifunctional weir influenced the water level at the Geoyrong and Daesan observation stations on the Nam River and the water quality based on automatic monitoring at the Chilseo station on the Nakdong River was affected strongly by the Nakdong River and partly by the Nam River.

• Journal of Environmental Science International
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• v.27 no.6
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• pp.371-381
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• 2018

Multifunctional weirs constructed through the Four Major Rivers Restoration Project are operated as management water levels. The purpose of this study was to evaluate the effect of water level in the main stem on the tributary water level according to multifunctional weir operation, because the operation of multifunctional weirs for water level management influences the drainage of tributaries. In this study, water level pressure gauges were installed and spatial and temporal water quality was observed. The LOcally Weighted Scatterplot Smoothing (LOWESS) technique was applied to the Nakdong River and the Baekcheon Junction, both upstream of the Gangjeong-Goryeong weir, in order to analyze water quality trends. When considering the overall analysis and observations, it was found that the water quality forecasting point located at the Baekcheon estuary point should be transferred to the Dosung Bridge, which is located upstream of the Sunwon Bridge.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.630-636
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• 2008

Monitoring the location of the shoreline and foreshore changes through the time and core tasks are carried out by coastal engineers for a wide range of research. With the advent of digital imaging technology, the shore-based video monitoring system provides many advantages than field surveys. This study presents the development and construction(installation) of video monitoring system to assist the study of coastal and shoreline dynamics and evolution, especially sandbar variation at the Nakdong river estuary. For the purpose of this study, at high building near the Dadea-po beach (St. 2) and Jinudo(island) (St. 1) foreshore region, where coastline variation is highly active, 5 video cameras installed; the coastline movement has monitored since Aug. 2007 using the systems. From the image results of video camera, the 'Spit' type sandbar appears at the foreshore region of Doyodeung and Dadea-po beach and measured the deposition process of Jinudo(island) foreshore region. As a result, the monitoring system using video-based technique built in this study would be able to identify changes in the area and width of shoreline and beach of Nakdong river estuary.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.481-496
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• 2019

The Ministry of Environment has measured streamflow at eight-day intervals for the estimation of standard flow of the Total Maximum Daily Loads (TMDL) system. This study identified the availability of the partially measured the eight-day interval data for estimating standard flow and found the optimal extension techniques of standard flow. The study area was selected for the Nakbon-A watershed in the Nakdong River, and four streamflow record extension techniques of standard flow were considered: extension, percentile, drainagearea, and regional regression methods. The flow duration curve (FDC) using the eight-day interval streamflow data indicated very high Nash and Sutcliffe Efficiency (NSE) values above 90 % from FDC-II to FDC-VII compared to FDC-VIII, the standard FDC. This result demonstrates that FDC using daily data of three-six cumulative years could represent standard FDC fairly well. For the streamflow record extension techniques of standard flow, the percentile method was selected as the optimal alternative, showing the minimal difference from FDC-VIII. These results validate the availability of the eight-day interval streamflow data in the standard flow estimation and the application of extension techniques. It seems that these results could reduce the uncertainty of partially measured streamflow data for water quantity and quality management.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.266-271
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• 2005

In this study, following works have been carried out : division of Nakdong River Basin into 25 sub basins, development of a technique to evaluate spatial distribution of rainfall and analysis of rainfall data of 169 stations, selection of control points, and selection of a hydrologic model(SSARR). The runoff analysis showed that the surface-subsurface separation and soil moisture index parameters are the most important two to the simulation result.

• Journal of Korea Water Resources Association
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• v.50 no.9
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• pp.587-595
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• 2017

Hydraulic characteristics affecting sediment transport capacity due to the weir operations were investigated and developed sediment rating curves for four gaging stations (Nakdong, Gumi, Waegwan, and Jindong) in Nakdong River. Analysis found that the sediment transportaion capability had been decreased and it could be proved from the field measurement records in 2013. Applicabilities of nine sediment transport prediction techniques, which are imbeded in GUIDE program, were examined and adopted for the four gaging stations. Analysis of sediment balance for Nakdong River, including 9 major tributaries, had been carried out with pseudo 2-D numerical model and found that: 1) sedimentation phenomena will be prevailed along the Nakdong River. 2) Engelund-Hansen technique shows the least error in estimation of sediment balance. 3) Engelund-Hansen technique most appropriately describes the sediment characteristics for four gaging stations. 4) Estimated error from the sediment balance for Nakdong River was smaller than the error caused by the estimation of sediment incomming from 9 tributries. Therefore, it is necessary to improve the accuracy of predicting the sediment incomming from the tributaties for better sediment balance analysis.

• Water Engineering Research
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• v.2 no.2
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• pp.113-121
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• 2001

The objective of this study is to develop a prediction mode for a flood forecasting system in the downstream of the Nakdong river basin. Ranging from the gauging station at Jindong to the Nakdong estuary barrage, the hydraulic flood routing model(DWOPER) based on the Saint Venant equation was calibrated by comparing the calculated river stage with the observed river stages using four different flood events recorded. The upstream boundary condition was specified by the measured river stage data at Jindong station and the downstream boundary condition was given according to the tide level data observed at he Nakdong estuary barrage. The lateral inflow from tributaries were estimated by the rainfall-runoff model. In the calibration process, the optimum roughness coefficients for proper functions of channel reach and discharge were determined by minimizing the sum of the differences between the observed and the computed stage. In addition, the forecasting lead time on the basis of each gauging station was determined by a numerical simulation technique. Also, we suggested a model structure for a real-time flood forecasting system and tested it on the basis of past flood events. The testing results of the developed system showed close agreement between the forecasted and observed stages. Therefore, it is expected that the flood forecasting system we developed can improve the accuracy of flood forecasting on the Nakdong river.