• Membrane and Water Treatment
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• v.10 no.1
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• pp.99-104
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• 2019

In Korea, nonpoint pollutants have a significant effect on rivers' water quality, and they are discharged in very different ways depending on rainfall events. Therefore, preparing an optimal countermeasure against nonpoint pollutants requires much monitoring. The present study was conducted to help prepare a method for installing an automatic nonpoint pollutant measurement system for the cost-effective monitoring of the effect of nonpoint pollutants on rivers. In the present study, monitoring was performed at six sites of a river passing through an urban area with a basin area of $454.3km^2$. The results showed that monitoring could be performed for a relatively long time interval in the upstream and downstream regions, which are mainly comprised of forests, regardless of the rainfall amount. On the contrary, in the urban region, the monitoring had to be performed at a relatively short time interval each time when the rainfall intensity changed. This was because the flow rate was significantly dependent on the rainfall's intensity. The appropriate sites for installing an automatic measurement system were found to be a site before entering the urban region, a site after passing through the urban region, and the end of a river where the effects of nonpoint pollutant sources can be well-decided. The analysis also showed that the monitoring time should be longer for the rainfall events of a higher rainfall class and for the sites closer to the river end. This is because the rainfall runoff has a longer effect on the river. However, the effect of nonpoint pollutant sources was not significantly different between the upstream and the downstream in the cases of rainfall events over 100 mm.

• Water for future
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• v.15 no.3
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• pp.49-55
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• 1982

The purpose of this study is to examine the methods of estimation, comparing U.S. SCS method and $\Phi$-index with effective rainfall. And also comparision was made among SCS method, Chow method and Mockus method as to the peak discharge of design storm hydrograph by small river basin. Hydrological data of the Shin river basin which was used in this study and the results of study are as follow; 1) As a result of applying the SCS method to determine the effective rainfall out of total rainfall, it turned out that the everage CN of the basin as obtained by the analysis of hydrologic soil-cover complex was varied as follows; AMC-I was 27.9%, AMC-II 16.4%, AMC-III 8.1% less than the value given by SC method using discharge measurement. 2) The comparision of effective rainfall by the ungaged SCS method with that of gauged $\Phi$-index method showed that the $\Phi$-index method showed that the $\Phi$-index method gives large value by 4.7% to those given by hydrograph. The result of analysis by the SCS method resulted in great difference from discharge measurement. 3) The comparision of SCS method, Chow method, and Mockus method showed that dimensionless hydrograph of SCS method and Chow method were close to the peak discharge of the gauged unit hydrograph, while the other methods gave far different results. 4) Attempts were made, for a better adaptation to the Shin river basin, to introduce lag time formula constant of dimensionless hydrograph of the SCS method by using the peak discharge of the gauged flow hydrograph.

• Journal of Korea Water Resources Association
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• v.49 no.3
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• pp.253-262
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• 2016

A Rating curve is a regression equation of discharge versus stage for a given point on a stream where the stream discharge is measured across the stream channel with a stage and discharge measurement. The curve is generally used to calculate discharge based on the stage. However, the existing approach showed problems in terms of estimating uncertainty associated with regression parameters including the separation parameter for low and high flow. In this regard, this study aimed to develop a new method for the aforementioned problems based on Bayesian approach, which can better estimate the parameter and its uncertainty. In addition, this study used a Bayesian Multi-Segmented (Bayesian M-S) model which is provided a comparison between the existing and proposed scheme. The proposed model showed better results for the parameter estimation than the existing approach, and provided better performance in terms of estimating uncertainty range.

• Textile Coloration and Finishing
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• v.6 no.2
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• pp.17-23
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• 1994

Carboxylic acid group gradient surface where the density of carboxylic acid groups changes gradually along the sample length was prepared. Carboxylic acid group gradient surface was produced by the treatment of low density polyethylene sheet using a corona with gradually increasing power, followed by the grad polymerization of acrylic acid. The prepared gradient surface was characterized by the measurement of water contact angle, Fourier-transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1977-1983
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• 2009

This paper described partial discharge(PD) patterns depending on types of insulation defects in CNCO-W cable(Concentric Neutral Closs-linked Polyethylene Insulated Polyolefin-Water Proof Sheathed Power Cable). The PD measurement system consists of a coupling network, a detection impedance, and a low noise amplifier. A 16 bit, 250 MS/s data acquisition system was used to analyze PD patterns. To simulate insulation defects in a power cable, a needle with the curvature radius of $10{\mu}m$ was inserted into the insulation part. We measured phase ($\Phi$), magnitude (q), and counts (n) of PD pulse for the defects, and classified PD patterns using the PRPD (phase Resolved Partial Discharge) method. From the analysis of acquired PD signals, we could find that a unique PD pattern is formed according to the types of defect.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.699-702
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• 2008

In this study, it has observed the precipitation and stage data at each point every ten minutes for gaining the sustainable, reliable and high-quality hydrological data through operating the experimental watershed in mountainous areas such as Gyecheon located in the upstream of Seom river that is the tributary of Nam-Han river. And it has regularly surveyed the runoff and verified the reliability of data using the uncertainty analysis at the gaging station. So, this study has developed the stage-discharge curve(rating curve) and these results are expected to be used as fundamental data for analyzing the circulation of water through surveying evapotranspiration, soil moisture and level of groundwater in watershed.

• Journal of Urban Science
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• v.10 no.1
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• pp.39-48
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• 2021

In this study, to evaluate the characteristics of the pollution in the major inflow tributaries and major environmental facilities in the watershed of Ara waterway, An inflow flow rate measurement and water quality analysis were conducted during dry and rainy seasons. In addition, the flow rate measurement, water quality analysis, and pollutant load at each monitoring point were compared and evaluated. Influx of BOD5, T-P and T-N into the tributaries of the ARA waterway watershed, excluding the Gulpo river watershed, during dry season were only 0.007%, 0.005% and 0.004% respectively of the incoming loads in the entire ARA waterway basin. In addition, it was confirmed that the discharge pollutant loads during rainfall event was about 440 times more for BOD5, about 545 times on T-P, and about 23 times on T-N in comparison to the pollutant loads during the dry days. When the Gulhyeon rubber dam was deflated, the discharged pollutant load during a rainfall was higher than the estimated load at the G7 monitoring point because the deposited pollutants from the upstream riverbed flowed down. Therefore, during a rainy season, it is necessary to manage the influx of high-load water pollutants from the overflow and deflation of the Gulhyun rubber dam as well as to find a strategy to reduce the pollutant loads in the Gulpo river watershed.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.511-522
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• 2015

This study assessed the impact of uncertainties in flood data on the results of flood frequency analysis for Han river basin. To meet this aim, this study quantified assessment focused on the index flood and quantile by regional flood frequency analysis using the flood data from 17 water level gauges in Han river basin. We analysed the results categorized by three cases according to the characteristics of the measured data. Firstly, we analyzed the regional flood frequency for the water level gauge in the Pyungchang river basin to investigate the impact of water level data. The results has the error of 0.240 with respect to the mean flood. Secondly, we examined the impact of uncertainty in measurement data generated by the application of rating on the results of regional flood frequency analysis. We have compared the results by applying the rating estimated for each year to the one by the recently estimated rating. The results showed that the mean error has 0.246 in terms of the mean flood. Finally, we have inferred the regional flood frequency analysis results with the regulated flow in the downstream area of dams. The regulated specific discharge in the downstream area of dams controlled by dam operation showed a large difference to the estimated specific discharge in the downstream area of dams by extension of the natural specific discharge in the upstream area using the regionalization method.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.118-128
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• 2017

The scope of this work is to determine and compare the effect of electron temperature ($T_e$) and number density ($N_e$) on the yield rate and concentration of reactive chemical species ($^{\bullet}OH$, $H_2O_2$ and $O_3$) in an argon, air and oxygen injected negative DC (0-4 kV) capillary discharge with water flow(0.1 L/min). The discharge was created between tungsten pin-to pin electrodes (${\Phi}=0.5mm$) separated by a variable distance (1-2 mm) in a quartz capillary tube (2 mm inner diameter, 4 mm outer diameter), with various gas injection rates (100-800 sccm). Optical emission spectroscopy (OES) of the hydrogen Balmer lines was carried out to investigate the line shapes and intensities as functions of the discharge parameters such as the type of gas, gas injection rate and inter electrode gap distances. The intensity ratio method was used to calculate $T_e$ and Stark broadening of Balmer ${\beta}$ lines was adopted to determine $N_e$. The effects of $T_e$ and $N_e$ on the reactive chemical species formation were evaluated and presented. The enhancement in yield rate of reactive chemical species was revealed at the higher electron temperature, higher gas injection rates, higher discharge power and larger inter-electrode gap. The discharge with oxygen injection was the most effective one for increasing the reactive chemical species concentration. The formation of reactive chemical species was shown more directly related to $T_e$ than $N_e$ in a flowing water gas injected negative DC capillary discharge.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.99-108
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• 2007

The purpose of this study was to investigate characteristics of concentrations of pollutants such as TN (Total Nitrogen), TP (Total Phosphorus) and COD (Chemical Oxygen Demand) in outflow from a nonpoint source dominated watershed ($6.7km^2$). Regular flow measurement and water sampling were taken at five-day intervals during two years (February 2002 to January 2004) in the Ingyeong River, a tributary of the Han River. The mean concentrations of pollutants during rainy days were significantly (p<0.05) higher than those during dry days. For dry days, the flow-weighted mean concentration (0.06 mg/L) of TP during paddy irrigation periods were higher than that (0.02 mg/L) during non-irrigation periods. The seasonal mean concentration of TN was highest in spring likely due to nitrogen fertilization, but those of TP and COD were highest in summer due to particulate phosphorus and sediment-associated organic matter caused by increased discharge. The pollutant concentrations significantly increased with discharge, suggesting that the measures to reduce the increase in the concentrations during storms are needed to control nonpoint source pollution.