• 상하수도학회지
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• 제22권1호
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• pp.93-103
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• 2008

This study was conducted to optimize a unidirectional flushing program in distribution pipes by analysis of water pressure, velocity, quality, and other parameters during flushing. As a result, correlation coefficient between flushed pipe length and the flushing duration was obtained $R^2=0.83$ and the equation $Y_{Time}=0.0571{\cdot}X_{Pipe\;length}+4.7648$ for 10 pipes. The averaged flushing velocity in the pipes, 1.1 m/s, was enough to remove loose deposits on the inner wall of the pipes. 3 of 92 water samples taken during flushing met the National Drinking Water Quality Standard for Fe and Mn, but not for Al. Turbidity less than 1 NTU is suggested for the appropriate criteria to finish flushing in pipes. The coefficient of determination ($R^2$) between turbidity and TSS was 0.95 and the equation was induced as $Y_{TSS}=1.2068{\cdot}X_{Turbidity}$. The amount of removed deposits could be estimated from the turbidity data of discharged water in field because turbidity and TSS in the discharged water is highly correlated.

• Smart Structures and Systems
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• 제25권1호
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• pp.23-35
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• 2020

It is important to take into account the thermal behavior in assessing the structural condition of bridges. An effective method of studying the temperature effect of long-span bridges is numerical simulation based on the solar radiation models. This study aims to develop a time-varying solar radiation model which can consider the real-time weather changes, such as a cloud cover. A statistical analysis of the long-term monitoring data is first performed, especially on the temperature data between the south and north anchors of the bridge, to confirm that temperature difference can be used to describe real-time weather changes. Second, a defect in the traditional solar radiation model is detected in the temperature field simulation, whereby the value of the turbidity coefficient t_u is subjective and cannot be used to describe the weather changes in real-time. Therefore, a new solar radiation model with modified turbidity coefficient γ is first established on the temperature difference between the south and north anchors. Third, the temperature data of several days are selected for model validation, with the results showing that the simulated temperature distribution is in good agreement with the measured temperature, while the calculated results by the traditional model had minor errors because the turbidity coefficient t_u is uncertainty. In addition, the vertical and transverse temperature gradient of a typical cross-section and the temperature distribution of the tower are also studied.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.801-805
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• 2004

In this work, the fundamental study of on-line monitoring of $SiO_2$ particles in the size range of 40 nm to 725 nm was carried out using turbidimetry. The size of particle was measured using a field emission scanning electron microscope (FE-SEM). The factors affecting on the turbidity were discussed, for example, wavelength, size, and concentration. In order to observe the dependence of turbidity on the wavelength, a turbidimetric system equipped with charged coupled detector (CCD) was built. The shape of the transmitted peak was changed and the peak maximum was shifted to the red when the concentration of particle was increased. This result indicates that the turbidity is related to the wavelength, which corresponds to the characteristic of the Mie extinction coefficient, Q, that is a function of not only particle diameter and refractive index but also wavelength. It is clear that a linear calibration curve for each particle in different size can be obtained at an optimized wavelength.

• 한국물환경학회지
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• 제26권4호
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• pp.673-680
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• 2010

Environmental factors and phytoplankton community in Lake Doam were monthly investigated at 3 stations from April 2009 to November 2009. During the study period, the concentrated rainfalls occurred at between July and August and then the TP and turbidity were sharply increased in in-lake. A total of 91 phytoplankton species was classified and these were consisted of 38 Bacillariophyceae, 35 Chlorophyceae, 10 Cyanophyceae, and 8 other species. Bacillariophyceae and Chlorophyceae were dominated during the seasonal succession of phytoplankton community, especially summer season. Bacillariophyceae was dominated from spring season to summer season and Chlorophyceae was dominated at summer season and autumn season. However, the dominance of Cyanophyceae generally developed at summer season in eutrophic water was not observed. From the analysis of correlation coefficient between environmental factors and phytoplankton cell number, we confirmed that there was a negative correlation between turbidity and cyanobacteria cell number (P<0.01). This result indicated that turbid water acts as the inhibitor of the cyanobacteria growth than other phytoplankton community.

• 생태와환경
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• 제41권3호
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• pp.360-366
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• 2008

본 연구는 심수층의 고정 취수구를 통해 방류하는 안동댐을 대상으로 1일 최대 99.4 mm, 총 299.1 mm인 단일사상의 강우로 유입된 고탁수의 호소 내 시 공간적인 거동과 방류수의 탁도가 감소하는 경향을 조사하였다. 유입된 고탁수는 중류지점부터 호소 바닥에서 이탈되어 중층 밀도류로 최하류까지 이동하였다. 강우 이전의 호소 내 탁도는 10 NTU 이하의 균일한 분포를 보였으나 강우에 의해 수심 16 m에 최고 290 NTU의 고탁수대가 형성되었다. 고탁수는 강우 후 3일부터 방류수의 탁도를 상승시켰으며 5일째에 129 NTU로 최고 탁도를 보였다. 댐까지 이동한 탁수층은 취수구 상부 5 m 이내의 수심에 최고 농도로 분포하였으며 하류 방류에 의해 탁수층의 두께와 농도가 감소하였다. 방류수의 탁도가 30 NTU까지 감소하는데 38일, 강우 이전의 상태로 회복되는데 87일이 소요되었으며, 감소경향의 상관계수는 각각 0.96, 0.97이었다. 중층에서 밀도류를 형성한 고탁수는 취수구 직상부에 분포하면서 취수구 방향으로 점차 유인되어 하류로 배출되었으며 호소 바닥으로의 침강은 일어나지 않았다. 안동호로 유입된 고탁수는 심층에 위치한 취수구를 통해 효과적으로 배출되므로 취수구 위치는 고탁수 배제에 적정한 것으로 판단된다.

• 한국해양학회지
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• 제21권2호
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• pp.101-109
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• 1986

경기만 식물플랑크톤 생태에 영향을 미치는 광조건을 알기 위하여 광도, 보상 깊이, 소광계수, 투명도, 부유물질등이 조사 연구되었다. 봄부터 가을까지는 식물플 랑크톤성장에 적절한 광도를 유지하였으나 가을에는 플랑크톤 성장을 제한할 정도 의 낮은 광도를 보였다. 투명도 및 보상깊이도 계절적인 변화를 보여 동계에는 표 층하 1-2m내에 국한되었다. 소광계수는 만 전체에 전반적으로 높은 양상을 보이고 뚜렷한 계절변화를 보였다. 이와같은 낮은 광도, 낮은 보상깊이, 투명도, 높은 소광 계수는 경기만 내 특징인 높은 탁도와 높은 부유물질 농도에 기인된다. 특히 겨울 철의 나쁜 광조건은 조류와 북서계절풍에 의한 심한 수괴의 혼합으로 미세 퇴적물 의 재 부유 현상에 기인된 것으로 보인다.

• 한국환경과학회지
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• 제23권5호
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• pp.839-852
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• 2014

The Ministry of Environment (MOE) has made more effort in managing point source pollution rather than in nonpoint source pollution in order to improve water quality of the four major rivers. However, it would be difficult to meet water quality targets solely by managing the point source pollution. As a result of the comprehensive measures established in 2004 under the leadership of the Prime Minister's Office, a variety of policies such as the designation of control areas to manage nonpoint source pollution are now in place. Various action plans to manage nonpoint source pollution have been implemented in the Soyang-dam watershed as one of the control areas designed in 2007. However, there are no tools to comprehensively assess the effectiveness of the action plans. Therefore, this study would assess the action plans (especially, BMPs) designed to manage Soyang-dam watershed with the WinHSPF and the CE-QUAL-W2. To this end, we simulated the rainfall-runoff and the water quality (SS) of the watershed and the reservoir after conducting model calibration and the model validation. As the results of the calibration for the WinHSPF, the determination coefficient ($R^2$) for the flow (Q, $m^3/s$) was 0.87 and the $R^2$ for the SS was 0.78. As the results of the validation, the former was 0.78 and the latter was 0.67. The results seem to be acceptable. Similarly, the calibration results of the CE-QUAL-W2 showed that the RMSE for the water level was 1.08 and the RMSE for the SS was 1.11. The validation results(RMSE) of the water level was 1.86 and the SS was 1.86. Based on the daily simulation results, the water quality target (turbidity 50 NTU) was not exceeded for 2009~2011, as results of maximum turbidity in '09, '10, and '11 were 3.1, 2.5, 5.6 NTU, respectively. The maximum turbidity in the years with the maximum, the minimum, and the average of yearly precipitation (1982~2011) were 15.5, 7.8, and 9.0, respectively, and therefore the water quality target was satisfied. It was discharged high turbidity at Inbuk, Gaa, Naerin, Gwidun, Woogak, Jeongja watershed resulting of the maximum turbidity by sub-basins in 3years(2009~2011). The results indicated that the water quality target for the nonpoint source pollution management should be changed and management area should be adjusted and reduced.

• 공업화학
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• 제33권6호
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• pp.563-573
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• 2022

This work aimed to develop a new equation for turbidity (Turb) simulation and prediction using statistical methods based on principal component analysis (PCA) and multiple linear regression (MLR). For this purpose, water samples were collected monthly over a five year period from Cheurfa dam, an important reservoir in Northwestern Algeria, and analyzed for 12 parameters, including temperature (T°), pH, electrical conductivity (EC), turbidity (Turb), dissolved oxygen (DO), ammonium (NH₄⁺), nitrate (NO₃^-), nitrite (NO₂^-), phosphate (PO₄^3-), total suspended solids (TSS), biochemical oxygen demand (BOD₅) and chemical oxygen demand (COD). The results revealed a strong mineralization of the water and low dissolved oxygen (DO) content during the summer period. High levels of TSS and Turb were recorded during rainy periods. In addition, water was charged with phosphate (PO₄^3-) in the whole period of study. The PCA results revealed ten factors, three of which were significant (eigenvalues >1) and explained 75.5% of the total variance. The F1 and F2 factors explained 36.5% and 26.7% of the total variance, respectively and indicated anthropogenic pollution of domestic agricultural and industrial origin. The MLR turbidity simulation model exhibited a high coefficient of determination (R² = 92.20%), indicating that 92.20% of the data variability can be explained by the model. TSS, DO, EC, NO₃^-, NO₂^-, and COD were the most significant contributing parameters (p values << 0.05) in turbidity prediction. The present study can help with decision-making on the management and monitoring of the water quality of the dam, which is the primary source of drinking water in this region.

• 한국환경과학회지
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• 제19권6호
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• pp.771-778
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• 2010

The prediction of discharge is very important in water resources management and plan. In this study, we have analyzed discharge data of site at up and down stream in watershed. In order to forecast discharge the regression equations were developed by measuring flow data. Also, to forecast the change of water quality followed by change of inflow the correlation relationship between inflow of the Youngchun site and the Chunhju dam was shown as very high. The forecast of inflow at the Chungju dam would be possible through flow analysis of the Youngchun site. And, it is possible to forecast water quality by flow analysis because the correlation relationship of SS and turbidity followed by change of flow for each station of investigation was very high.

• 물과 미래
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• 제15권3호
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• pp.23-36
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• 1982

The stochastic variations and structures of time series data on water quality were examined by employing the techniques of autocorrelation function, variance spectrum, Fourier series, autoregressive model and ARIMA model. These time series included hourly and daily observation on DO, turbidity, conductivity pH and water temperature. The measurement was made by automatic recording instrument at Noryangjin and Dook-do located in the downstream part of Han River during 1975 and 1976. Hourly water quality time series varied with the dominant 24-hour periodicity, and the 12-hour periodicity was also observed. An important factor affecting 24-hour periodic variation of DO is believed to be photosynthesis by algae. These phenomena might be attributable to periodic discharges of municipal sewage. Noryangjin site showed the more distinct 12-hour periodicity than Dook-do site did, and tidal effect might be responsible for the difference. The water quality, as measured by DO and turbidity, was better in the afternoon compared with the quality in the morning. This change can be explained by the periodic variation of DO, temperature and the amount of municipal wewage discharge. It was also observed that the water temperature at Noryangjin was higher than the temperature at Dook-do. This difference might have been caused by the pollutants that were added to the section between two sites. The correlation coefficients between some of the variables were fairly high. For example, the coefficient was -0.88 between DO and water temperature, 0.75 between turbidity and river flow, and 0.957 between water temperature and air temperature. The lag time of heat transfer from the air to the water was estimated as 24 days. The first order auto-regressive model was appropriate for explaning standardized hourly DO time series. The ARIMA model of (1, 0, 0) type provided relatively satisfactory results for daily DO time series after the removal of significant harmonic value.