• 한국전산유체공학회:학술대회논문집
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• 2002.10a
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• pp.127-132
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• 2002

Numerical and experimental works have been made in order to figure out the physical mechanism of thermal storage system for the determination of optimal design and to enhance the thermal efficiency of the system. To this end a computer program is developed and evaluated successfully against experimental data measured with a bench scale facility. Considering the thermal efficiency of storage is critically impaired by the mixing effect, the minimum flow mixing situation is calculated by the assumption of uniform plug-type flow as a reference condition. Further a parametric systematic calculations have been made for a hypothetical full-scale storage system with Fr, storage dimension, diffuser type and loading hour, etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.328-331
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• 2000

Carbon nanotube(CNT) was successfully grown on Ni-W alloyed substrate by applying PECVD technique(Plasma Enhanced Chemical Vapor Deposition). As a catalyst, Ni-W alloyed substrate was prepared by mechanical alloying method. In order to find the optimum growth condition, initially two different types of gas mixtures such ac $C_2$H$_2$-H$_2$and $C_2$H$_2$-MH$_3$were systematically investigated by adjusting results on the mixing ratio in temperature range of 500 to 80$0^{\circ}C$. In this work, we will report the preliminary results on the CNT processed by PECVD, which were characterized by XRD, SEM and TEM. Finally we will evalute the effect on CNT growth by changing many processing parameters, such as typical gas, mixing ratio between 2 mixture, plasma power and etc.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.111-121
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• 2007

The experimental design and response surface methodologies haven been applied to the investigation of the chemical coagulation of livestock wastewater. The chemical coagulation reactions were mathematically described as a function of parameters raping mixing (rpm) of chemical coagulation ($X_1$), slow mixing (rpm) of chemical coagulation ($X_2$), $FeCl_3 $ concentration (mg/L) ($X_3$) and pH ($X_4$) being modeled by use of the central composite design. Empirical models were developed to describe relationship between the experimental variables and response. Statistical analysis indicates that three factors ($X_1$: raping mixing (rpm), $X_2$: slow mixing (rpm), $X_3$: $FeCl_3 $ concentration (mg/L) on the linear term (main effect), slow mixing (rpm) (${X_2}^2$) on the non-linear term (quadratic), and two factors ($X_1-X_3$, $X_2-X_3$) on the non-linear term (cross-product) had significant effects, respectively. The estimated ridge of maximum responses and optimal conditions for CODcr using canonical analysis was 87.44% ($X_1$: 229 rpm, $X_2$: 51 rpm, $X_3$: 877 mg/L, $X_4$: 4.3). To confirm this optimum condition, three additional experiments were performed and the mean CODcr removal (%) and concentration (mg/L) with a standard deviation of $87{\pm}1.2%$ ($576{\pm}34ppm$) were obtained.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.427-434
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• 2000

Hydraulic conductivity of soil-cement was measured as a function of some selected construction variables that are often encountered in practice. They are initial (or compaction) water content, delayed compaction after mixing, and repeated freezing and thawing. Sandy and clayey soils were used. The hardening agent used was a cement based soil stabilizer consisting of 80% of ordinary Portland cement and 20% of a combination of supplementary materials. Hydraulic conductivity of soil-cement with varying initial water content was, in trend, similar to that of compacted clay. Hydraulic conductivity of soil-cement decreased with increasing initial water content and reached its minimum when compacted wet of optimum water content. Pore size distributions of soil cement at different initial water contents were analyzed using mercury intrusion porosimetry. The analysis showed that dryer condition led to the formation of larger pores with lesser total pore volume; smaller pores with larger total pore volume at wetter condition. Hydraulic conductivity of soil-cement increased by orders in magnitude when specimen underwent delayed compaction of longer than 4 hours after mixing and repeated freezing and thawing.

• Journal of the Korean Society of Food Culture
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• v.25 no.1
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• pp.54-60
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• 2010

The principal objective of this study was to determine the optimal mixing condition of two different amounts of cabbage and rice flour for the preparation of a cabbage cream soup. The experimental design was based on the central composite design methodology of response surface, which included 10 experimental points, including two replicates for the cabbage and rice flour. Physiochemical and sensory properties were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the mixed final product. Water content and pH values increased with increasing quantities of rice flour. Neither cabbage or rice flour affected the L and a values, but the b value increased with greater quantity of both ingredients. Viscosity increased with increasing added cabbage. Sensory evaluation results were significant in the predicted model for flavor (p<0.05), concentration (p<0.01) and overall quality (p<0.01). As a result, the optimum formulations by numerical and graphical methods were calculated as 111.79 g cabbage and 8.99 g rice flour.

• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.5-15
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• 2011

Recent increase of large scale construction near costal area has also increased the application of soft ground treatment. As a result, solidification with cement and lime which increases stability and durability of soils, is frequently used for surface layer stabilization in soft ground site. While stabilization of very soft clay with high plasticity and compressibility has widely been studied, studies on silty clay with low plasticity and compressibility are relatively rare. In this study, after stabilizing low plasticity silty clay of Songdo area with cement and lime under various water contents, mixing ratio, and curing time, uniaxial compression test and plate load test were performed. Strength properties from both tests were considerably consistent. And trackability of construction equipment on the treated surface layer of dredged land was estimated. Finally, optimum mixing condition for Songdo silty clay was proposed.

• Polymer(Korea)
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• v.32 no.1
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• pp.1-6
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• 2008

The adhesion behaviors and processability of NBR as a sealing material were investigated. In order to find the optimum formulation, the adhesive properties and processability were observed as the change of the contents of acrylonitrile (ACN) in NBR. Effects of Mooney viscosity, filler, plasticizer and crosslinking agent on the adhesion behaviors were also studied. The contents of ACN in NBR have great effects on adhesion behaviors and processability in NBR sealing. To know the optimum condition of roll mixing, degree of dispersion was investigated. It was confirmed that degree of dispersion was influenced by various factors such as mixing order, time, and temperature. The crosslinking system was studied as the observation of sulfur system, peroxide system, crosslinking density, and structure. From the variation of the dry condition and hexamine contents, the relation between adhesive and NBR was studied. These results show the adhesion properties and processability are dependent on the contents of ACN and crosslinking system.

• Korean journal of food and cookery science
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• v.22 no.1 s.91
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• pp.45-55
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• 2006

The purpose of this study was to determine the optimal mixing conditions of three different amounts of spinach powder, butter and egg for the preparation of spinach muffins. The mixing condition for spinach muffins was optimized by response surface methodology. Egg was the most influential on height. The maximum point was achieved with 30.08 g of spinach powder, 247.69 g of butter and 184.97 g of egg. The optimum mixing rates of spinach power, butter and egg were 29.51 g, 252.24 g and 192.33 g for color, 32.43 g, 249.87 g and 180.90 g for overall quality and $28\sim34\;g,\;250\sim260\;g\;and\;175\sim210\;g$ for maximum score of overall organoleptic quality, respectively.

• Journal of Animal Environmental Science
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• v.12 no.1
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• pp.41-44
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• 2006

Broiler manure has much nutrient that can be used as the organic fertilizer to enhance the fertility of soil. However, if it is used directly without biodegradation of organic materials and destruction of weed seed and harmful bacteria, it can produce the generation of weed and disease of plant. Composting of manure is a biodegradation of organic materials into inorganic materials and humus. To proceed biodegradation of manure effectively and enhance the composting performance, optimum environmental condition for microbial growing should be maintained. Environmental variables which can influence the growing activity of microbes are moisture content, pH, porosity, C/N of the composting materials and oxygen supply quantity. Oxygen and porosity are usually supplied by aeration or mixing of materials. This study was intended to investigate the effect of mixing frequency on the composting performance. Mixing of composting materials was performed by turning the bioreactor up and down by hand without any mechanical energy. The broiler manure was captured from the greenhouse type broiler ham as the compounds of broiler manure and rice-hulls, which were used as the base materials. To compost the compounds of broiler manure and rice-hulls, dairy manure was mixed to get appropriate characteristics of composting material. Composting temperature over $55^{\circ}C$ for killing pathogen and weed seed was maintained for longer period with increase of mixing frequency.

• Journal of Pharmaceutical Investigation
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• v.15 no.2
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• pp.83-90
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• 1985

The effects and the optimum manufacturing conditions for the preparation of synthetic aluminum silicate which has acid-consuming power and adsorbing capacity were investigated. The results are as follows: 1. The adsorbing capacity was affected by the mixing order of the reactants, that is, the excellent ones were obtained by the method which add the sodium silicate solution to the potassium alum solution. 2. Even though preparing by the bane manufacturing condition, the acid-consuming power is superior to the adsorbing capacity. 3. According to the Box-Wilson Plan, the optimum reaction conditions are concentration of sodium silicate solution; 38% w/w, settling time; 43 hours at room temperature, drying time; 13 hours at $110^{\circ}C$.