• Journal of Mechanical Science and Technology
• /
• v.15 no.1
• /
• pp.88-97
• /
• 2001

The present study numerically investigates the fuel-air mixing characteristics, flame structure, and pollutant emission inside a double-swirler combustor. A PSR(Perfectly Stirred Reactor) based microstructural model is employed to account for the effects of finite rate chemistry on the flame structure and NO formation. The turbulent combustion model is extended to nonadiabatic flame condition with radiation by introducing an enthalpy variable, and the radiative heat loss is calculated by a local, geometry-independent model. The effects of turbulent fluctuation are taken into account by the joint assumed PDFs. Numerical model is based on the non-orthogonal body-fitted coordinate system and the pressure/velocity coupling is handled by PISO algorithm in context with the finite volume formulation. The present PSR-based turbulent combustion model has been applied to analyze the highly intense turbulent nonpremixed flame field in the double swirler combustor. The detailed discussions were made for the flow structure, combustion effects on flow structure, flame structure, and emission characteristics in the highly intense turbulent swirling flame of the double swirler burner.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.32 no.4
• /
• pp.41-48
• /
• 2000

The main objective of this study was to investigate the packing state and optical properties of coated paper prepared with different coating colors by varying the blending ratio of such pigment as clay, $CaCO_3$, and plastic pigment. To evaluate the effect of packing state of pigment on the properties of coated paper, the coating thickness, which was theoretically calculated by specific gravity, and packing volume of pigment were used. It was found that there exists close relationship between the coating thickness and surface property of coated paper. For instance, the macro roughness(smoothness) of coated paper is closely related to bulkiness. Plastic pigments used in this research has a high finishing efficiency on the light weight coatings. Especially, hollow sphere pigment was very effective for improving the property of coated paper produced in this test. And when HSP was blended with $CaCO_3$the surface property such as smoothness and gloss improved significantly.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.48 no.5
• /
• pp.73-80
• /
• 2006

The mono-layer cover system is composed of soils only as a filling material and various plants are planted on the surface to control the water balance in the cover system. In this paper, the mono-layer cover system was considered as an alternative landfill final cover system and developed a model that could utilize industrial by-product (especially, coal ash & phosphogypsum) as additive filling materials. The mixture of granite soil, coal ash, and phosphogypsum was placed as a cover material in a box constructed with cement. Laboratory tests were carried out to investigate the environmental effect on the utilization of coal ash & phosphogypsum and to determine the mxing ratio of each materials. In the leaching test, all materials showed lower heavy metal concentration than the threshold values of regulation. The optimum mixing ratio of materials which was applied to field model test was determined to soil (4) : coal ash (1) : phosphogypsum (1) on the volume base. Field model tests were continued from February to July, 2004 in the soil box that was constructed with cement block. It was verified that coal ash and phospogypsum mixed with soil was to be safe environmentally and the water balance of mono-layer cover system was reasonable.

• Journal of Powder Materials
• /
• v.9 no.2
• /
• pp.89-95
• /
• 2002

Spherical fine powders of tungsten oxide powders were prepared by the emulsion evaporation method. The characteristics of the powders prepared were examined by means of TGA, X-ray diffraction, SEM and image analysis. The emulsions were prepared by fast mixing of aqueous phase containing tugsten and the organic phase which composed of kerosene, surfactant, and paraffin oil. Precursors were made by evaporating the emulsionin the kerosene bath at $160^{\circ}C$, and then calcined at $650^{\circ}C$ in order to produce tungsten oxide powders. The average particle size of the tungsten oxide powders was $0.5\mutextrm{m}$ and their shapes were spherical at the both case of w/o and o/w type emulsions. As the HLB value of the surfactant increased and the concentration of tungsten ions decreased the mean particle siqe of tungsten oxide powders decreased whereas agglomerationsize increased. The optimum concentration of Span 80 was 8 percent by volume, and the optimum stirring speed in the emulsion formation was 5000 rpm in order to obtain fine and well dispersed $WO_3$ powders.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.32-37
• /
• 2003

The amount of 4,500 drums of soil waste are temporarily stored in KAERI. In order to develop a technology for safe treatment of the soil waste, a number of tests were performed by applying cement and polymer as solidifier. Immobilization specimens were adequately made by mixing soil waste with cement or polymer Compressive strength and leaching tests were performed in order to see the fulfillment to standard of disposal following the storage. A compressive strength, about 5,300psi was obtained from both solidifiers of cement containing 40% of soil waste and polymer containing 60%. The obtained leaching index was larger than 11, which was satisfied with the relevant standard. It was shown that the integrity of the solidified waste much depends on homogenization in solidifying process and hardness of the specimen. Volume reduction of solidified waste with polymer was better than that of cement by 20%.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.158-161
• /
• 2003

To develop an effective adsorbent for radio active Carbon Dioxide, $^14CO_2$, which is discharged to nearby atmosphere from nuclear power plants of CANDU type, we made some preliminary adsorbents and tested their abilities of $CO_2$ removal. The chemical agents used was LiOH and we supported or impregnated it on the surface or the internal volume of activated Carbon(GW-H). The physical and chemical properties of various adsorbents were measured using methods such as XRD, BET. SEM images were taken to investigate the change of surface morphology of the adsorbents. Finally, amount of $CO_2$ adsorption of them were verified under specific conditions. We found that mechanical mixing of LiOH and activated Carbon showed the maximum $CO_2$ removal ability, while surface activation of activated Carbon by Nitric Acid-treatment enhanced its $CO_2$ removal efficiency to some degree.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.2
• /
• pp.178-185
• /
• 2005

The synergistic effect of ethylene/propane mixture on soot formation is studied experimentally using a concentric co-flow diffusion burner, which provides the stratified fuel mixture. The soot volume fraction, soot particle diameter, number density and PAH concentrations are measured with various fuel supply configurations and compared to the homogeneously mixed case. When propane is supplied through the inner nozzle, an increase of soot formation is observed. However, when propane is supplied through the outer nozzle, a decrease is observed. The reaction path of PAH's formed from the pyrolysis process of propane is likely to be responsible to the observed differences. When propane is supplied through the outer nozzle, PAH's are formed in the relatively near oxidation region and exposed to the oxidization environment; on the other hand, when propane is supplied through the inner nozzle, PAH's are not likely to be oxidized and thus get involved in soot formation process. The synergistic effect in ethylene/propane diffusion flames is found to be affected not only by the com position of the mixture but also by the way of mixing.

• Korean journal of food and cookery science
• /
• v.18 no.2
• /
• pp.238-246
• /
• 2002

The purposes of this study were to provide the basic information on the cookies made with barley and oatmeal powder and to establish an optimum formula for the development of cookies with high content of fiber. Cookie samples were prepared with barley and oatmeal at various mixing ratios (2:0, 1:1, 2:1, 0:2), and the chemical properties, textural characteristics, and sensory properties of them were evaluated. The contents of carbohydrate and moisture of barley cookies were higher than oatmeal cookies, but the contents of crude protein, crude fat, crude ash and total fiber of oatmeal were higher than those of barley. The moisture content was the highest in the cookies of oatmeal and the lowest in barley-used ones. The cookie volume was increased by the addition of barley and oatmeal. The results of sensory evaluation showed that the cookies containing barley and oatmeal (2:1) was significantly more preferable in overall acceptability than the others. Hunter color test showed that the lightness was the highest in control, but the redness and yellowness were increased in the cookies with barley and oatmeal compared with the control.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.7 no.3
• /
• pp.30-37
• /
• 2003

Spray angle of dual swirl injector is established according to the velocity ratio at orifice exit. Due to the internal mixing at recess and lack of correlation for the combined two fluid injection, prediction of spray angle is very difficult. This study deal with experimental work and numerical simulation on spray angle with different recess length. Among the multiphase flow models, the VOF model was selected to simulate the spray angle. Feasibility of numerical analysis are confirmed by comparing the results with the experimental data, and the effect of recess on spray angle are analyzed for single and combined spray case.

• The Korean Journal of Food And Nutrition
• /
• v.12 no.3
• /
• pp.252-257
• /
• 1999

In an attempt to evaluate the effects of calcium on paste or gelatinization properties by amylograph and mixing properties by farinograph of wheat flour and on viscosity property cooking quality textural and sensory properties of Ramyon were examined. The contents of calcium used were from 1.0% to 3.0% based on flour weight. The viscosity property of wheat flour with calcium was increased the initial past-ing temperature but the amylograph peak viscosity were decreased in vice versa. The farinograph absorp-tion stability and breakdown were increased by calcium. The shear extrusion force and hardness of Ram-yon manufactured with calcium were shown much higher value than those of control. At cooking quality examination of Ramyon manufactured with calcium weight of cooked Ramyon was increased by volume was decreased. Extraction amounts of Ramyon manufactured with calcium during cooking were much smaller than those of control. These changes will provided many advantages in the preparation of Ram-yon. The I2 reaction value of Ramyon manufactured with calcium and control were shown to almost same values. Sensory properties of cooked Ramyon which was manufactured with calcium showed quite acceptable. Based on the cooking and sensory evaluation test addition of 0.3% calcim to wheat flour may be suitable for processing Ramyon.