• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.207-215
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• 2006

The characteristic floc growth of Al-based coagulants was investigated in the aspect of mixing intensity and visualization of generated flocs during coagulation and flocculation processes. Zeta potential of turbid particles in the artificial water nearly approached to zero at pH 8-9, in which TDS and conductivity were minimized. The removal rate of turbidity and phosphate was maximized at the optimal mixing intensity of rapid and slow mixing stages. After the rapid mixing stage of coagulation process, small particles ($3-5{\mu}m$) were abruptly generated, and higher mixing intensity made more numbers of flocs. With the progress of slow mixing stage, the number of small particles were decreased with the simultaneous increase of intermediate particles ($7-21{\mu}m$). The number of large particles (>$23{\mu}m$) were maximized at the lowest rapid mixing intensity of $95.1sec^{-1}$, whereas small particles (<$5{\mu}m$) were maximized at the highest rapid mixing intensity of $760.7sec^{-1}$.

• Journal of Korean Society for Quality Management
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• v.16 no.1
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• pp.15-22
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• 1988

This paper analysis the process capability by applying experiment design to control alcohol in soluble matter mixing process of laundry soap. The results are summarized as follows: (1) Alcohol insoluble matter shows the tendency of increasing according to the mixing temperature (A) and beating velocity (B). (2) The most suitable working condition of the mixing process is $A_2B_2$, and 95% confidence limit of alcohol insoluble matter is $22.06{\pm}0.77%$. (3) The process capability index ($C_p$) of the mixing process is improved from 0.64 to 1.68.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.5
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• pp.201-206
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• 2018

This study investigated the changes in pore water quality of polluted sediment by mixing ratio of granulated coal ash. The mesocosm experiments were carried out with 0%, 10%, 30% and 50%, respectively, of the material mixture ratio relative to the sediments. According to the results of the experiments, pH increased depending on the mixing ratio. Phosphate and ammonia concentrations were significantly decreased in the mixing ratio of 30% and 50% compared to the control (p < 0.05). The concentration of hydrogen sulfide was reduced by 72% at the mixing ratio of 10%, and it was not detected at the mixing ratio of 30% and 50%. This study was confirmed that granulated coal ash can change the pore water quality of polluted sediments in proportion to the amount of material. However, the effect of the mixing ratio between 30% and 50% was not significantly different, thus it is concluded that mixing of 30% of the volume of the sediment is economically feasible.

• Honam Mathematical Journal
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• v.30 no.3
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• pp.479-486
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• 2008

Let {${\Omega}$, F, P} be a probability space and {$X_n{\mid}n{\geq}1$} be a sequence of random variables defined on it. We study the Hajeck-Renyi-type inequality for p..mixing random variable sequences and obtain the strong law of large numbers by using this inequality. We also consider the strong law of large numbers for weighted sums of ${\tilde{\rho}}$-mixing sequences.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.2
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• pp.50-56
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• 2014

Conventional coagulation-gravity settling processes in heavy metal removal have a problem in coagulant cost and instability of the settling efficiency. The authors investigated the effects of pH and slow mixing conditions on heavy metal hydroxide precipitation and the particle size distribution of the precipitate for a precipitation-membrane separation process. The optimum pH values for the hydroxide precipitation ranged from 9 to 10. The addition of $FeCl_3$ did not enhance the heavy metal removal. 20 min of slow mixing at 70 rpm showed the maximum heavy metal removal to meet the water quality criteria for effluent discharge. More than 99.9% of the heavy metal precipitate particles were bigger than $2{\mu}m$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.63-69
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• 2004

It is of great interest to enhance mixing performance in a microchannel in which the flow is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved in this laminar flow regime. In this regard, we present a new chaotic passive micromixer, named Barrier Embedded Micromixer (BEM), of which the mixing mechanism is based on chaotic flows. In BEM, chaotic flow is induced by periodic perturbation of the velocity field due to periodically inserted barriers along the channel wall while a helical type of flow is obtained by slanted grooves on the bottom surface of the channel in the pressure driven flow. To experimentally compare the mixing performance, a T-microchannel and a microchannel with only slanted grooves were also fabricated. All microchannels were made of PDMS (Polydimethylsiloxane) from SU-8 masters that were fabricated by conventional photolithography. Mixing performance was experimentally characterized with respect to an average mixing intensity by means of color change of phenolphthalein as pH indicator. It was found that mixing efficiency decreases as Re increases for all three micromixers. Experimental results obviously indicate that BEM has better mixing performance than the other two. Chaotic mixing mechanism, suggested in this study, can be easily applied to integrated microfluidic systems , such as Micro-Total-Analysis-System, Lab-on-a-chip and so on.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.24-30
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• 2002

The laboratory adsorption batch tests were performed to investigate the adsorption characteristics of Pb on kaolinite. The characteristics such as adsorption equilibrium time, adsorption capacity, adsorption isotherm were studied, and also the effects of pH and the mixing ratio on the adsorption of Pb on kaolinite were investigated. Test results show that the adsorption equilibrium state was reached within 24 hours, and the adsorbed amount of Pb increased, but the adsorption efficiency over the initial concentration of 198 mg/l decreased, with increasing the initial concentration of Pb. And the adsorption constant, 1/n was obtained 0.9584 by Freundlich isotherm equation. Regardless of the initial concentration of Pb. the adsorbed amount of Pb as well as the adsorption efficiency were increased with increasing pH values and converged to a certain constant value above 8 of pH values. And also the adsorbed amount of Pb increased with the mixing ratio, but its efficiency increased with the mixing ratio up to 8 and then showed the decreasing tendency above that.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.91-97
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• 2000

The objective of this study was to evaluate the possiblity of Foodwaste and co-treatment with other waste for vermistabilization. The value of oxidation-reduction potential(Eh) of the dewaterized foodwaste by a plant of subatmospheric evaporation was a possitive(+) value indicating, but the values of pH, salinity was idicating an unfavorable condition for earthworm life. The paper mill mixing waste properties by ripening for 20days were changed into the favorable range for earthworm. The growth of earthworms in foodwaste and mixing waste of paper mill 30% was found to be 68%, 84% for the survival rate, 227%, 275% for the liveweight increasing rate, respectively. The ingestion rate of foodwaste and mixing waste of paper mill 30% indicate 0.72g/g·d, 0.81g/g·d, respectively. About 62∼75% of ingestion amount produce cast and characteristics of cast indicate pH 6.1∼6.5 organic component 34∼42%, salinity 0.35∼0.4, CEC 73∼94 me/100g, N, P, K concentration 0.8∼1.2%, 0.4∼1.6%, 0.43∼0.5% respectively. Therefore it can be evaluated that the casts are good soil condition and organic fertilizer.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.56-63
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• 2015

In this study, the exhaust characteristics of the diesel engine for the change of the mixing ratio of biodiesel fuel were quantitatively analyzed by using the numerical analysis method. As the fuel used in the experiment, the diesel and biodiesel(waste oil, soybean oil), the mixed fuel BD2(Diesel only), BD3, BD5, BD20, BD50 and BD100 were used. The injection pressure($p_{inj}$) was set to 400bar, 600bar, 800bar, 1000bar and 1200bar as the experimental variable. Also the concept of the standard deviation, Pearson's correlation coefficient and Spearman rank-order correlation coefficient based on the statistics was introduced in order to analyze the exhaust characteristics of the quantitative NOx and Soot according to the injection pressure and the mixing ratio variation of biodiesel blending fuel. It is considered that as a result of studies, for the waste oil, NOx and Soot can be simultaneously reduced through control of the mixing ratio at the regions of $p_{inj}=400bar$ and $p_{inj}=600bar$, and the Soot can be reduced without affecting on the emission of NOx at more than $p_{inj}=800bar$. For the soybean oil, NOx and Soot can be simultaneously reduced at $p_{inj}=400bar$ and the Soot can be reduced without affecting on the emission of NOx at $p_{inj}=600bar$.

• Journal of Environmental Health Sciences
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• v.19 no.2
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• pp.1-9
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• 1993

In public water supply systems, Alum and/or PAC being used as a coagulant. It is well known that their use increased frequently the concentration of residual aluminum in filtered water upon operating conditions. This study was conducted to find the optimum conditions that both the concentration of residual aluminum and turbidity are minimized by changing such factors as pH, temperature, alum dosage, mixing rate, alkalinity and hardness. The results can be summarized as follows: The pH values for the minimum concentration of residual aluminum and turbidity as a given experimental condition were found at pH 6 and pH 7 respectively, the apparent clarity was best at pH 8. The floc settling rate was the greatest at pH 6.5, but the turbidity was high at the same condition. The more alum dosage, the higher the concentration of residual aluminum. However the alum dosage less than 15 mg/l tend to decrease in turbidity. Restabilization and enmeshment occurred near 15 mg/l and 20 mg/l of alum dose respectively. With the increase of mixing rate (rapid and slow), the concentration of residual aluminum and turbidity are increased and the same trend was found in increment of mixing time. At low water temperature, the concentration of residual aluminum was decreased, but turbidity was increased. It was confirmed that alkalinity had an effect on the coagulation efficiency, but hardness did not.