• Journal of Environmental Science International
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• v.22 no.5
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• pp.581-589
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• 2013

Surface Image Velocimetry(SIV) is an instrument to measure water surface velocity by using image processing techniques. Since SIV is a non-contact type measurement method, it is very effective and useful to measure water surface velocity for steep mountainous streams, such as streams in Jeju island. In the present study, a surface imaging velocimetry system was used to calculate the flow rate for flood event due to a typhoon. At the same time, two types of electromagnetic surface velocimetries (electromagnetic surface current meter and Kalesto) were used to observe flow velocities and compare the accuracies of each instrument. The comparison showed that for velocity distributions root mean square error(RMSE) was 0.33 and R-squared was 0.72. For discharge measurements, root mean square error(RMSE) reached 6.04 and R-squared did 0.92. It means that surface image velocimetry could be used as an alternative method for electromagnetic surface velocimetries in measuring flood discharge.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.543-549
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• 2001

This research estimated stream discharges indirectly by hydraulic channel routing. Only stage data from three stage stations and river cross section data were used to estimate Manning roughness coefficients and to compute stream discharges. When the discharges were estimated a stage-stage set of conditions was used for upstream-downstream boundary conditions. The research used the data from the upper Mississippi River. The hydraulic channel routings were performed by DWOPER (operational dynamic wave model). The global optimization program of SCE-UA was used to improve the roughness coefficient estimation module of the modified Newton-Raphson method in DWOPER. The results from SCE-US were better. For the case study of a flood, most estimated discharges except a few show errors within 10%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.465-472
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• 2002

This paper presents a study on the aging and recovery of HTV (high temperature vulcanized) silicone rubber used for outdoor insulators. UV irradiation, corona discharge and water immersion were employed as factors of the artificial aging. The effects of changes derived from these stresses on the tracking and arc resistance of silicone rubber were examined. We have investigated the aging phenomena of HTV silicone rubber by the above stresses using the surface energy calculation with contact angle measurement, solvent-extraction, and surface/volume resistivity and so on. These results showed that UV irradiation and corona discharge lead to nearly the same surface oxidation, but the percentage change of mobile low molecular weight by these stresses was different. Furthermore, the oxidized layer induced under UV irradiation restricted the recovery of hydrophobic surface. Water immersion little lowered hydrophobicity level and leaded to a loss of tracking and arc resistance. The degradation mechanism based on our results was discussed.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.299-304
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• 1998

Flood control of the Mekong delta should be developed over time for rural as well as urban areas. The hydraulic modelling effort is aimed an investigating flow distribution and water level. For the flood control study the flood model made with the VRSAP program is used. Concerning future improvement of the models it is recommended to improve the quality of water level and discharge, extend the number of the measuring locations needed for input for the models, systematically review and analyze future measurement campaigns in order to obtain better understanding of the complex hydraulic aspects, verify and update the topographical data used to model the rivers and cannals, carry out detailed calibration and verification of the models on water levels, discharges etc.

• Water for future
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• v.29 no.3
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• pp.129-142
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• 1996

This study investigates the magnitude of errors that can be expected in integrating sediment concentration in a vertical, basede on a single-point measurement, because of errors in input data. Potential error sources, including sampler location, water surface elevation, bed elevation, fall velocity, $\beta$ value, and $\kappa$ value were comparatively examined using data from a special study on the Rio Grande Conveyance channel in New Mexico. It is concluded that simple forms of equations for the vertical distribution of velocity and sediment concentration based on a single-point field sample of suspended sediment. The most uncertain point in the computation is related to the Rouse number z in the equation for the vertical concentration distribution of suspended sediment.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.113-121
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• 2012

The study was carried out to investigate the dimension of irrigation canal, and measure the water flow of those diverted from Kimje main canal in Dongjin irrigation area. The rating curves indicating the relationships between water level and discharge of the lateral canals were induced using the measured data with high regression coefficients of 0.957~0.999 at inlet points and 0.932~0.998 at end points, respectively. And Manning's roughness coefficients were estimated as the ranged from 0.015 to 0.074 at inlet points and 0.056 to 0.089 at end points with rectangular type of concrete open irrigation canals, the Manning's roughness coefficients of the end points were less than those values of the end points, which may be considered as the deposition of the bottom sediments.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.338-347
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• 2006

A small hydro-power plant using the seawater used as the cooling (circulated) water and discharged is under construction. The bigger size of the small hydro-power plant, the better in order to maximize the efficiency and the electric power. The optimal size, however, should be determined in the constraints of the channel un-disturbed range. The water level change should be checked in detail based on the hydraulic behaviour. In this study, the FLOW3D model, three-dimensional flow model, is setup using the flow measurement data in the effluent discharge channel and the flow pattern changes due to the small hydro-power plant construction are predicted by the model. The plant construction makes the increasing of the water level, and the water level in the upstream of the channel weir is increased 65 cm from 4.32 m to 4.97 m, in the condition of the design discharge $156m^3/s$ and the movable weir height of the hydro-power plant 3.8 m.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1198-1202
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• 2004

초음파를 이용한 측정은 하천의 반대편에 흐름방향에 경사지게 초음파를 발사하여 다시 반사되어 오는 시간차를 기록함으로써 주어진 길이에서 유속을 연속적으로 측정하는 것이다. 하류로 내려가는 음파는 음향 측선(acoustic path)과 평행한 유속 성분 때문에 상류로 올라가는 음파보다 빠른 속도를 가진다. 탄천 및 괴산댐에 초음파 유량 측정시스템을 시험 설치하고 운영 결과를 검토하였다. 시험적용결과 연속적인 유량자료 획득이 가능하였으며, 기존 유속면적법 대비 $4.21\%$의 상대오차를 지니고 있어 기존 방법과 비교적 일치하는 측정결과를 나타냈다. 또한 지표유속(Index Velocity)를 활용한 단일회선 유량산정법을 검토한 결과, 다회선에 의해 운영한 결과와 평균 $2.9\%$의 상대오차를 지니고 있었다. 이 방법은 조석구간 및 배수영향을 받는 구간에서 작은 비용으로 연속유량자료를 획득할 수 있는 방법으로 판단된다. 시험적용 결과 개선해야 할 사항으로는 안정적인 자료 획득을 위한 초음파 변환기의 개선, 자료의 필터링 기술의 정밀화, 그리고 유량산정 방법에서 정확도 향상 기술 개발 등이 도출되었다. 초음파 유량 측정시스템은 자료의 연속성을 확보할 수 있는 점에서 매우 중요한 의미를 지니고 있다. 지금까지의 연속 유량 산출법은 연속적인 수위를 측정하고 각 수위에 따른 유량 측정 후 수위-유량관계를 통하여 연속적인 유량을 산출하였다. 그러나 초음파 유량 측정 시스템은 직접 유속과 수위를 측정하여 연속유량이 산출되기 때문에 연속유량 산출에 비교적 간편하다고 할 수 있다. 또한 정확도 면에서 기존 유량 측정법인 유속-면적법의 불확실도 $5\%\~10\%$에 비교하여 $5\%$ 내외의 정확도 수준을 지니고 있어 정확도 향상을 기대할 수 있다. 경제적인 측면에서도 매년 측정사업에 소요되는 비용과 비교하였을 때 장기적으로는 경제적인 방법이 될 수 있다.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.3-12
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• 2018

The objective of this study was to evaluate the radius of influence of effluent of water treatment system developed for the purpose of improvement of reservoir water quality using fluorescent dye (Rhodamine-WT) tracer experiment and 3-D numerical model. The tracer experiment was carried out in a medium-sized agricultural reservoir with a storage capacity of $227,000m^3$ and an average depth of 1.6 m. A guideline with a total length of 160 m was installed at intervals of 10 m in the horizontal direction from the discharge part, and a Rhodamine measurement sensor (YSI 6130, measurement range $0-200{\mu}g/L$) was used to measure concentration changes in time, distance, and depth. Experimental design was established in advance through Jet theory and the diffusion process was simulated using ELCOM, a three dimensional hydraulic dynamics model. As a result of the study, the direct effect radius of the jet emitted from the applied water treatment system was about 50-70 m, and the radius of physical effect by the advection diffusion was judged to be 100-120 m. The numerical simulations of effluent advection-diffusion of the water treatment system using ELCOM showed very similar results to those of the impact radius analysis using the tracer experiment and jet flow empirical equations. The results provide valuable information on the spatial extent of the water quality improvement devices installed in the reservoir and the facility layout design.

• Journal of the Korean Chemical Society
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• v.13 no.4
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• pp.401-407
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• 1969

The results of water analysis for 10 stations in the main Naktong and 11 stations in the tributaries from March to December 1968 are as follows: The water quality of the Naktong River Basin is generally the frist class of water, especially the tributaries, Hwang river, Nam river, Milyang river, Naesongchun, Hoechun, Wichun and Panbyunchun were dissolved in less than 100 mg/l as the amount of the total ion of the main component. In comparison with river discharge, the amount of the total ion of the main component is decreased in June and July, because of the river discharge is increased in those periods. According to the measurement of the conductivity and the hardness, the better water quality is distinguished by the following order: lower part of river (Namji), middle part of river (Waegwan), upper part of river (Yean). The conductivity of Kumho river, Tongchon is higher than the middle part of the main river and Nam river, Chongam is smaller than lower part of the main rivller. The variation of the amount of the total ion of main component in the basin is mainly effected by $HCO_3^-, SO_4^{-2}, Cl^-, Ca^{+2}$. The relationship between $[K^+]\;and\;[C^l-]\;and\;[Na^+]\;and\;[Cl^-]\;are\;[K^+]=0.04\;[Cl^-]+1.7\;mg/l,\;[Na^+]=0.06\;[Cl^-]$ mg/l .The main river was much contaminated by Kumho river and C.O.D. at Gang-chung, Kumho river in June was recorder over the standard about 7 times.