• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.1
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• pp.25-33
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• 1998

An experimental study has been carried out to obtain optimal conditions for turbulent mixing of two fluid streams at various angle branches by a flow visualization method. The main purpose of this study is the utilization of flow visualization method as a fast and efficient way to find the optimal mixing conditions when several flow control parameters are superimposed. It is verified that the optimal conditions estimated by flow visualization method have good agreement with the concentration field measurements. The results demonstrate that the diameter ratio is mainly attributed to the mixing phenomena than the branch pipe angle and the Reynolds number. The most striking fact is that there exists the best diameter ratio, d/D.ident. O.17, which requires the minimum momentum ratio in the range of the present experiment. The velocity ratio for the optimal mixing condition has a value within 2 to 16 according to the different flow parameters.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.262-268
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• 1998

This research is to examine the selected method of optimal mixing proportion and cost analysis in the super flowing concrete. As confined water $ratio($\beta_p$)$ and K is introduced, itis to establish optimal mixing design of super flowing concrete according to the steps of paste, mortar and concrete. From paste and mortar test, it was led to $$\beta_p$$ and $K_p$satisfying the optimum condions depending on the kinds of binders. Then $$\beta_p$$ and $K_p$ is reflected to the mix condition of super flowing concrete. The result of test, the mix condition of super flowing concrete satisfied the quality performance of concrete with adjustment of additional rate of the superplasticizer. Besides, in case of design strength $350kg/\textrm{cm}^2$ of concrete, material cost in super flowing concrete is able to be reduced 5~16% in replacement of fly ash 30% in ordinary portland cement and slag cement.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.231-238
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• 2016

In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%~40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.519-523
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• 2009

In this study, the base mixing ratio was determinated to estimate the optimal mixing ratio of material with a change of mixing ratio of micro cement, sand, foaming agent, plasticizer by testing the unconfined compressive strength test. The unconfined compressive strength test was performed to grasp a engineering characteristics of with a change of micro cement, bubble. The results of test, the unconfined compressive strength increased with a micro cement's increase and bubble's decrease. In the future, it will be secured that is reliable datas from laboratory of various condition and in-situ tests to develop optimal lightweight foamed concrete.

• Korean journal of food and cookery science
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• v.22 no.2 s.92
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• pp.164-172
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• 2006

The purpose of this study was to find the optimal mixing condition of three different amounts of pine leaf powder, butter and sugar for preparation of pine leaf cookies. The optimum mixing condition for pine leaf cookies was optimized by response surface methodology The optimum mixing rates of pine leaf powder, butter and sugar were 8.6 g, 252.8 g and 154.1 g for color, 8.4 g, 240.7 g and 149.8 g for appearance, 8.8 g, 246.5 g and 154.7 g for flavor and 10.9 g, 277.1 g and 134.6 g for texture respectively. The optimum mixture ratio which fulfilled all items was pine leaf powder 9.4 g, butter 270.5 g and sugar 141 g.

• The Korean Journal of Malacology
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• v.17 no.2
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• pp.95-104
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• 2001

To determine optimal conditions for measurement of the clearance rate in feeding experiment of an intertidal bivalve Glauconome chinensis, effects of starvation, extent of mixing at subsampling, and initial prey concentration were assessed. Experiments were conducted separately for each condition with different treatments. Two-way ANOVAs showed that there were significant differences in clearance rates among different starvation periods (p<0.001), extents of mixing (p = 0.005), and prey concentrations (p < 0.001). Starvation for 1 or 2 days gave rise to 2 to 3-fold increase in the clearance rate. After starvation for 5 days, the clearance rate decreased seriously, implying loss of physiological status. It is suggested that animals should be fed during acclimation. The differences of the clearance rates between gentle and vigorous mixings were significant, but the differences were smaller than that among different incubation times. It was found that vigorous mixing is not necessary. The effect of initial prey concentration was great. However, optimal prey concentration could not be determined at any fixed value. Experiments with multiple concentrations of algal prey are recommended. Optimal incubation time for measurement of the clearance rate of G. chinensis was determined to be 2-4 hours.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.3
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• pp.44-51
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• 2001

Sedimentation characteristics such as SS, $BOD_5$, COD removal efficiency of waste water in the toilet paper mill using milk carton were examined. Optimum dosage of coagulant, rapid mixing time and slow mixing time were determined by turbidity, SS, COD, $BOD_5$ and then equation for treatment efficiency was suggested. Mechanical strength of floc was determined by turbidity. For the coagulant, polyacrylamide (PAM) is more efficient for removing pollution than the aluminium sulfate. Effective mixing ratios of PAM and aluminum sulfate to remove pollution are 70:30 and 30:70. The lowest turbidity was showed when rapid mixing at 300 rpm after coagulant injection was applied. That which indicates the highest point of flocs mechanical strength.

• Journal of the Korea Concrete Institute
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• v.11 no.5
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• pp.41-49
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• 1999

This study dealt with the applicability and quality control of the concrete using fly ash produced in combined heat power in a construction site. Firstly, chemical and physical characteristics of the fly ash produced in combined heat power plant re analysed. Also, after investigating the properties of flesh and hardened concrete through various experiments, the fly ash concrete was placed in depositing construction in Ulsan Petrochemical Service Co. This field application was focussed on the quality control system in the site as production, placing and curing of concrete. As the result of this study, the quantity of CaO in the fly ash is relatively high based on the chemical analysis. The fly ash concrete showed slumping maintenance and high viscosity properties in the optimal mixing conditions (W/B:44~45%, S/a:$45\pm$2%, W:185kg/m). And, quality control and assurance of the fly ash concrete in actual site were verified by various testing methods.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.370-374
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• 2001

The degree of iron recovery from dust agglomerates was investigated experimentally to determine the optimum mixing ratio of coke in cold bonded pellet(CBP) which is fed into electric arc furnace(EAE) in the minimill plant. From the XRD analysis for EAF dust, magnetite(Fe$_3$O$_4$) and franklinite(ZnFe$_2$O$_4$) was identified as major components. Maximum iron recovery was obtained for the solid carbon content of approximately 18 weight percent. From plant trials of CBP composed of this optimal mixing condition, it was observed that electric power consumption and sulfur content increased with increasing the quantity of CBP.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.687-696
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• 2007

To increase the reliability of auto-ignition in CAI engines, the thermodynamic properties of intake flow is often controlled using recycled exhaust gases, called internal EGR. Because of the internal EGR influence on the overall thermodynamic properties and mixing quality of the gases that affect the subsequent combustion behavior, optimizing the intake and exhaust valve timing for the EGR is important to achieve the reliable auto-ignition and high thermal efficiency. In the present study, fully 3D numerical simulations were carried out to predict the mixing characteristics and flow field inside the cylinder as a function of valve timing. The 3D unsteady Eulerian-Lagrangian two-phase model was used to account for the interaction between the intake air and remaining internal EGR during the under-lap operation while varying three major parameters: the intake valve(IV) and exhaust valve(EV) timings and intake valve lift(IVL). Computational results showed that the largest EVC retardation, as in A6, yielded the optimal mixing of both EGR and fuel. The IV timing had little effect on the mixing quality. However, the IV timing variation caused backflow from the cylinder to the intake port. With respect to reduction of heat loss due to backflow, the case in B6 was considered to present the optimal operating condition. With the variation of the intake valve lift, the A1 case yielded the minimum amount of backflow. The best mixing was delivered when the lift height was at a minimum of 2 mm.