• 상하수도학회지
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• 제14권4호
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• pp.328-336
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• 2000

In order to compare the effect of water quality on two service systems, tank and direct connection service, we selected randomly 30 rooftop tanks installed in the buildings with five or fewer floors, and collected water samples from each tank as well as tap water by direct service. At the same time each tank was investigated on their cleanliness and sanitary control. 30 water samples from direct service met Korean Drinking water quality standard. But 5 tank water samples(17%) were not able to meet Coliform or Total Colony Counts standard and free chlorine of 12 tank water samples(40%) were less than 0.2mg/L. Also Fe, Turbidity, TOC, Total Algae in tank water were higher than tap water on direct service. We concluded that thorough health control of water tank is necessary and conversion into direct connection service results in improving tap water quality importantly.

• 상하수도학회지
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• 제33권6호
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• pp.413-420
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• 2019

Pretreatment system of desalination process using seawater reverse osmosis(SWRO) membrane is the most critical step in order to prevent membrane fouling. One of the methods is coagulation-UF membrane process. Coagulation-UF membrane systems have been shown to be very efficient in removing turbidity and non-soluble and colloidal organics contained in the source water for SWRO pretreatment. Ferric salt coagulants are commonly applied in coagulation-UF process for pretreatment of SWRO process. But aluminum salts have not been applied in coagulation-UF pretreatment of SWRO process due to the SWRO membrane fouling by residual aluminum. This study was carried out to see the effect of residual matal salt on SWRO membrane followed by coagulation-UF pretreatment process. Experimental results showed that increased residual aluminum salts by coagulation-UF pretreatment process by using alum lead to the decreased SWRO membrane salt rejection and flux. As the salt rejection and flux of SWRO membrane decreased, the concentration of silica and residual aluminum decreased. However, when adjusting coagulation pH for coagulation-UF pretreatment process, the residual aluminum salt concentration was decreased and SWRO membrane flux was increased.

• Preventive Nutrition and Food Science
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• 제13권2호
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• pp.117-121
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• 2008

The effects of water dropwort on the physical characteristics of tofu were investigated and consumer acceptance test was conducted. pH decreased significantly with increasing water dropwort concentration from 0 to 3%, whereas titratable acidity showed the reverse trend (p<0.05). The amount of water dropwort did not significantly influence the moisture content up to 2% substitution (p>0.05). Turbidity increased significantly with increasing water dropwort concentration (p<0.05). A significantly lower moisture content in 3% water dropwort tofu may be attributed to the denser structure and hardness of that was significantly higher than those of the other samples (p<0.05). Even though $a^*$-values of 3% water dropwort tofu was lower than that of control, $a^*$-values increased significantly with increasing water dropwort content (p<0.05). On the contrary, $b^*$-values decreased significantly with increasing water dropwort content (p<0.05). 2% water dropwort tofu was found to be the best with respect to its overall acceptability score.

• 상하수도학회지
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• 제13권3호
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• pp.61-72
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• 1999

To obtain the experimental data for design and operation of actual filtration processes, a sand filter and three kinds of dual media filters in pilot-plant scale were operated in this study. We analyzed the effect of filter medium composition on the filter performance and the effects of backwash water flow rates, length of stream line and air flow rate on the filter backwash efficiency. We also compared the efficiencies of the combined air-water backwashing and the water backwashing in dual media filters. As the backwash water flow rates or the length of stream line increased, the final turbidity of backwash water was decreased and the filtration duration time after backwash was increased. In the case of the combined air-water backwashing, the backwash water quantity needed for backwashing the dual media filters could be decreased. The total volume of filtered water for the dual media filters during filter run was over three times larger than that for the sand filter. The dual media filters could be operated at a high filtration rate of 360 m/day.

• 한국식품영양학회지
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• 제30권4호
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• pp.847-851
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• 2017

This purpose of this study was to investigate cooking characteristics of noodles prepared by adding 0, 2, 4 or 6 percent of Capsosiphon fulvescens to wheat flour containing konjac powder. Water binding capacity was significantly increased with increasing amounts of Capsosiphon fulvescens. Weight and volume of cooked noodles increased significantly in proportion with the amount of Capsosiphon fulvescens. Turbidity of the soup after cooking also increased with the addition of Capsosiphon fulvescens. Brightness(L) and redness(a) were decreased with addition of Capsosiphon fulvescens. Yellowness(b) increased. The color value of cooked noodles was decreased compared with that of wet noodles. Sensory evaluation scores revealed that cooked noodles with 4 percent addition group were highest in terms of color, flavor and overall acceptability. This study validates that addition of Amorphophallus konjac and 4 percent Capsosiphon fulvescens may improve functionality and preference of noodles.

• 한국패류학회지
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• 제29권3호
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• pp.239-244
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• 2013

Mass mortalities of farmed shellfish, mostly in summer season, thus named mass summer mortalities, have been a global issue in shellfish aquaculture. The 2013 mass summer mortalities in the confined waters of Goseong Bay, Goseong, Korea were quite a unique and intensive for two farmed species, the Pacific oysters, Crassostrea gigas, and bay scallops, Argopecten irradians. The mortalities were progressive from the bottom of the suspended oysters and caged scallops in the waters, reaching up to 80% for the oyster and 95% for the scallop in about 20 days after the first occurrence, early August, 2013. We monitored a wide range of environmental factors, including water temperature, dissolved oxygen (DO), salinity, turbidity, acidity (pH), organic and inorganic matters, chemical oxygen demand (COD), suspected pathogenic agent, and phytoplankton composition throughout the water column where the two species were suspended or caged. Our survey concluded that the hypoxia or anoxia might be a major cause of the mortalities. Here, we detailed the mortalities and ways to arrive at the conclusion.

• Ocean and Polar Research
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• 제40권4호
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• pp.191-202
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• 2018

In this study we conducted a weekly monitoring exercise at a fixed station in the saltwater zone during the dry season (Jan-Mar, 2013) and wet season (Jun-Aug, 2013) to understand the fluctuations in phytoplankton communities and environmental factors in the Youngsan River estuary altered by a dike constructed in the coastal area. Phytoplankton communities displayed seasonality; diatoms were dominant during the dry season whereas dinoflagellates were dominant during the wet season. T-test analysis showed that water temperature was significantly different between the seasons whereas freshwater discharge from the dike was not significantly different. This suggests that seasonal variations of phytoplankton are more likely affected by water temperature than freshwater discharge. However, a short-term fluctuation was also observed in response to freshwater discharge; freshwater species appeared during or after the discharge in the dry and wet seasons and blooms of harmful species developed after the discharge. Phytoplankton communities may be affected by changes in physical factors such as turbidity and salinity and nutrient supply resulting from freshwater discharge. Especially, the nutrient supply may directly contribute to the harmful algal blooms (HABs) composed of dinoflagellates which can adapt to low salinity after freshwater discharge.

• Advances in Energy Research
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• 제8권2호
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• pp.111-123
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• 2022

Solar Energy is the energy of solar radiation carried by them in the form of heat and light. It can be converted into electricity. Solar potential depends on the site's atmosphere; the solar energy distribution depends on many factors, e.g., turbidity, cloud types, pollution levels, solar altitude, etc. We estimated solar radiation with the help of the Ashrae clear-sky model for three locations in Pakistan, namely Pasni, Gwadar, and Jiwani. As these locations are close to each other as compared to the distance between the sun and earth, therefore a slight change of latitude and longitude does not make any difference in the calculation of direct beam solar radiation (BSR), diffuse solar radiation (DSR), and global solar radiation (GSR). A modified formula for declination angle is also developed and presented. We also created two different models for Ashrae constants. The values of these constants are compared with the standard Ashrae Model. A good agreement is observed when we used these constants to calculate BSR, DSR, GSR, the Root mean square error (RMSE), Mean Absolute error (MABE), Mean Absolute percent error (MAPE), and chisquare (χ²) values are in acceptance range, indicating the validity of the models.

• 한국식품저장유통학회지
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• 제31권1호
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• pp.46-63
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• 2024

This study evaluated the impact of storage temperature on the quality characteristics of texturized vegetable protein (TVP). TVP was prepared by mixing defatted Daewon soybean flour at 80℃, gluten, and corn starch in a 5:3:2 ratio, which was then extruded at a screw speed of 250 rpm and a barrel temperature of 190℃ with moisture addition at 9 rpm. Subsequently, the extruded TVP was vacuum-sealed in polyethylene packaging and stored at -20℃, 0℃, and 4℃ for 9 days. Texture analysis revealed that the curing rate followed 4℃ > 0℃ > -20℃ sequence. No significant color variation was observed across the storage conditions, although water content increased at all temperatures. Notable changes were detected in moisture absorption capacity (%) and solid leaching (%), following the order of -20℃ > 0℃ > 4℃. The turbidity of the solution released during cooking varied, with the highest to the lowest sequence being -20℃ > 4℃ > 0℃, while pH levels remained neutral. Regarding free amino acids, sweetness and textural quality improved with storage across all temperatures, whereas bitterness components diminished at 4℃. The study suggests that refrigerated storage at 4℃ is a viable method for distributing TVP, which was previously distributed only in a frozen and dry state.

• 상하수도학회지
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• 제23권6호
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• pp.799-810
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• 2009

With time, the stable management of turbidity is becoming more important in the water treatment process. So optimization of coagulation is important for the improvement of the sedimentation efficiency. we evaluated the mixing and hydrodynamic behavior in the coagulation basin using Computational Fluid Dynamics (CFD). The items for evaluation are a location and the speed of agitator and angle of an injection pipe. The results of the CFD simulation, the efficacy of mixing in the coagulation basin was not affected according to one or two injection pipe and angle of an injection pipe. If there is a agitator near outlet of coagulation basin, the efficacy of mixing don't improve even though the speed of agitator increase. So location of agitator is perfect when it locate center at the inlet stream. The coagulation basin at this study, the proper speed of agitator is form 20rpm to 30rpm.