• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.499-505
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• 2011

The mixing behavior of turbidity currents in a reservoir is closely related with the annual temperature change of the reservoir. In the summer, the reservoir has a well defined structure: one or two thermoclines and some layers of different densities. This density stratification inhibits vertical mixing and affects various hydrodynamic processes within the reservoir. Therefore, many reservoirs can be operated to release water of the specific quality with the selective withdrawal. In this study, the hydraulic experiments were performed to analyze the efficiency of selective withdrawal. The velocity distributions are measured with PIV in the stratified tank with the "two-tank" method. The relationship between the Richardson number and the selective withdrawal efficiency are provided using the measured velocity distributions.

• The Journal of Industrial Distribution & Business
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• v.9 no.12
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• pp.23-29
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• 2018

Purpose - The purpose of this study is to apply a cost effective ultrasonic odor reduction method that generated micro-bubbles using ejector to the Southeast Asian wastewater market. Research design, data, and methodology - A leather maker located in Ansan-city, Gyunggi-do, South Korea was sampled from the collection tank to select experimental materials. Experimental setup consisted of circulating water tank-air ejector-ultrasonic device, and circulating wastewater. Sample analysis was performed by CODcr, T-N, T-P, and turbidity by the National Environmental Science Institute. Results - Experimental results show that it is most effective in removing odors when the frequency range of ultrasonic wave is 60~80 Khz and the output is 200 W. It showed that the concentration of complex odor dropped from a maximum of 14,422 times to a minimum of 120 times. Also, analysis of ammonia and hydrogen sulfide in specific odor substances has shown that they were reduced from 1.5 ppm to 0.4 ppm and from 0.6 ppm to 0.1 ppm, respectively. Conclusions - It is possible to shorten more than 12 hours in the treatment of micro-organisms. It can be seen that the processing time of odor after ultrasonic treatment in the pre-treatment facility is reduced by 25% when compared to the resultant micro-organisms after the chemical treatment, that is, the time of the bio-treatment of micro-organisms. Based on the results, it was confirmed that the pre-treatment method using the ultrasonic and the air ejector device of the experiment shows the effect of reducing the water pollutants and odor more effectively in a relatively short time than the conventional advanced oxidation method.

• Hwankyungkyoyuk
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• v.19 no.2 s.30
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• pp.96-107
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• 2006

Inquiry has great value in environmental education(EE). Being able to see the world environmentally through 'inquiry-based environmental education' can be an important value and goal of EE. In this study, we intended to develop an EE program of measuring activity of dissolved oxygen(DO), based on the theory of 'inquiry-based EE'. Especially, we recognized the potential that DO meter can be used in 'inquiry-based EE', and we tried to develop a model of inquiry-based EE using DO meter. As a result of this research, we present specific models of inquiry-based EE about how to perform measuring activity of DO and how to use the DO meter in laboratories and streams from the perspective of inquiry of water environment. In the process of program development, we considered organization of the inquiry process, use of concept and knowledge, scientific inquiry and insightful inquiry, integration, sustain-ability, content components of 'Environmental Studies for EE', developmental level and in-forest of students. The developed EE model is a scientific inquiry model, pursuing 'explanation' based on data collection. Through this model, we tried to make students see water environment more deeply. The developed program can be applied to various water environments, like laboratories, streams, ponds, etc. It can be more effective inquiry activity if we perform measuring activities simultaneously with PH, electrical conductivity, and turbidity meters.

• Journal of the Korean Applied Science and Technology
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• v.35 no.2
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• pp.472-477
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• 2018

The excess molar volumes of a general anesthetics on Purple membrane and Red membrane separated by extraction in Halobacteriun Halobium and in suspensions of vesicle have been determined at $25^{\circ}C$, it was used a excess volume dilatometer. The anesthesia characteristics of general anesthetics, Propofol was fined by our study to correlate with excess molar volume. Excess volume changes of the vesicle measured by excess volume dilatometer, which is an important amino acid and lipid in the purple membrane and red membrane by means of specific weight in Halobacteriun Halobium, were studied by absorption intensity at 280 nm and 330 nm. The particle size analysis and relative turbidity of Purple membrane and Red membrane by means of Propofol were measured for mechanical properties. In the samples where Propofol is incoporated in vesicle, especially, the excess molar volume of PM + RM + Propofol is the greatest than the excess molar volumes of PM, and RM.

• Applied Biological Chemistry
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• v.35 no.2
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• pp.69-75
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• 1992

Viscosity changes of acidified milk at the various pH $ranges(5.2{\sim}4.2)$was measured as a function of temperature. The rate and extent of acid-induced coagulation of milk protein were monitored by turbidity changes as a function of temperature, preheating and salt. Relative viscosities of acidified milk were also measured. The coagulation of casein occurred in a specific pH range and was accompanied by a sharp increase in viscosity at pH of $5.0{\sim}5.2$, depending on the heating temperatures. Onset pH of coagulation and maximum coagulation rate were enhanced by increasing temperatures and preheating process and reduced by addition of salt. Relative viscosity of acidified milk was reversed at the same conditions, reflecting the size of casein coagulum formed was related to the coagulation rate.

• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.35-46
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• 2006

In this study, we proposed a layout of the integrated decision support system in order to prevent the contamination and to manage risk in water supply networks for safe and smooth water supply. We evaluated the priority of risk factors to detect anomaly in water supply networks using PROMETHEE and ANP techniques, which are applied to various Multi-Criteria Decision Making area in Europe and America. To develop the model, we selected pH, residual chlorine concentration, discharge, hydraulic pressure, electrical conductivity, turbidity, block leakage and water temperature as the key data item. We also chose pipe corrosion, pipe burst and water pollution in pipe as the criteria and then we present the results of PROMETHEE and ANP analysis. The evaluation results of the priority of risk factors in water supply networks will provide basic data to establish a contingency plan for accidents so that we can establish the specific emergency response procedures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.2
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• pp.159-172
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• 2019

This study investigated the effects of dietary monobasic potassium phosphate (MKP) on the growth of the far eastern catfish Silurus asotus and four leafy vegetables in a hybrid biofloc technology aquaponic system. To an experimental diet containing 45% protein and 7% lipid, 1, 2, 3 or 4% MKP was added and was designated as MKP1, MKP2, MKP3, and MKP4, respectively. The optimum MKP levels were determined for the growth of fish and four leafy vegetables over 10 weeks. After the 10-week feeding trial, weight gain, feed efficiency, specific growth rate and protein efficiency ratio were higher in the fish groups fed MKP2 and MKP3 than in the other groups (P<0.05). The growth of the four leafy vegetables was also higher in the fish groups fed MKP2 and MKP3. Water quality [dissolved oxygen, pH, water temperature, electrical conductivity, turbidity, total ammonia nitrogen (TAN), $NO_2-N$, $NO_3-N$ and $PO_4-P$] was measured six times a week using a portable water quality meter and reagent measurements. The TAN (4.58-20.40 mg/L), $NO_3-N$ (24.12-52.40 mg/L) and $PO_4-P$ (20.38-48.48 mg/L) levels increased with time, while the $NO_2-N$ level remained below 0.1 mg/L throughout the study.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.242-256
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• 1997

The physico-chemical properties and possible biological functionalities of commercially available persimmon vinegars were studied by measuring the specific gravity, turbidity, color, pH, total acidity, reducing sugars, alcohols, total nitrogen content, composition of organic acids and amino acids, soluble pectin, soluble tannin, ascorbic acid, acetoinic compounds, electron donating ability and nitrite scavenging ability. Persimmon vinegars had low specific gravity(1.005-1.0200) and lightness(40.03-54.95), but high turbidity (0.12-1.311, absorptivity at 660 nm), redness(1.65--0.64) and yellowness(4.54-8.14) compared to the other fruit vinegars reported. These physical property values of the individiual product differed greatly. The tested persimmon vinegars contained relatively large amount of reducing sugars(0.45-0.84%, w/v), alcohol(0.16-3.18%, w/v) and total nitrogen(30-60mg%, w/v). The pH values (average 3.70) of products were relatively high and the total acidities(average 3.04%, w/v) of the tested persimmon vinegars were lower than that($TA{\geq}4.0%$) specified by the Korean standard for fruit vinegar. The major organic acids identified in the tested products were acetic acid(17.6-72.9%) and lactic acid(25.1-74.1%). The acetic acid contents in the 5 products out of the 7 tested persimmon vinegars were lower than lactic acid content. The level of free amino acids of the persimmon vinegars were relatively high in arginine, methionine and threonine. Persimmon vinegars contained relatively large amount of soluble pectin(91.8-232.8mg%, w/v), soluble tannin(49.0-161.7mg%, w/v) and ascorbic acid(12.8-29.6mg%, w/v). The persimmon vinegars were high in 2,3-butanediol (average 166.90ppm) and acetoin(average 111.43ppm). The persimmon vinegars showed strong electron donating ability and nitrite scavenging ability.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.677-686
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• 2006

This study was the effectiveness of two downflow BAF(Biological Aerated Filter) systems at conventional water treatment system. A BAF reactor placed in front of coagulation and sedimentation tanks(Mode A) and after coagulation and sedimentation tanks(Mode B) that were compared in terms of removal of suspended particles, organic matters, and ammonia nitrogen. The suspended particles removal efficiency was over 80% for both Mode A and B, although Mode A gave slightly better results. $BOD_5$ removal and nitrification efficiencies were more than 90% for both reactor. The organic matter and ammonia removals were also superior in the Mode A. The biofilm thickness and biomass increased as increment of EBCT and the upper part of reactor more about 30% than lower part. The specific oxygen uptake rate(SOUR) was higher the upper part of reactor and Mode A than the lower part of reactor and Mode B. A cost analysis showed that the Mode A system was more cost effectiveness. It could save the coagulant dose by about 67% and the chlorine demand by about 95%. The ideal place to put the BAF reactor was in front of the coagulation/sedimentation process.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.406-413
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• 2012

Effect of three additives, chitosan, ferric chloride, and MPE50 on membrane fouling reduction was studied. They were introduced with various dosing rate into activated sludge, and changes in filtration resistance measured by the batch cell filtration test were evaluated. Both the filtration resistance and the specific cake resistance were minimized at 20 mg/g-MLSS with chitosan, 70 mg/g-MLSS with ferric chloride, and 20 mg/g-MLSS with MPE50 addition, respectively. Introduction of the additives into the activated sludge resulted in reduction of not only cake resistance, but also fouling resistance. However, the chitosan addition to three different activated sludge resulted in three different optimal dose of 10, 20, 30 mg/g-MLSS, respectively. This implies that the optimal dose is dependent on sludge characteristics rather than a constant value. Overdose above the optimal dosage always aggravated filterability in all cases. Zeta potential of sludge flocs, relative hydrophobicity, floc size distribution, soluble EPS concentration and supernatant turbidity were measured in order to analyze fouling reduction mechanism. Nearly neutral surface charge along with the largest particle size was observed at the optimal dose. This could be explained by particle destabilization and restabilization mechanism as positively charged additives were injected into sludge flocs of negative surface charge. Both soluble EPS concentration and supernatant turbidity also showed the lowest value at the optimal dose. These foulants are believed to be coagulated and entrapped in sludge flocs during flocculation. Chitosan and MPE50 which are cationic polymeric substances showed higher reduction in both soluble EPS and fine particles comparing with ferric chloride.