• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.481-487
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• 2003

A technique for determination of proportions of char, coal ana coke is needed in order to monitor pulverized coal injection performance in operating blast furnace. Quantitative X-ray powder diffraction analysis can be applied to the problem providing that structural information on carbonaceous materials, coal, char, coke and their mixture are known. Chars were prepared from a coal at different temperatures (1000∼1400$^{\circ}C$) and were characterised by X-Ray powder Diffraction (XRD). The XRD result gave crystallite size (height Lc and diameter, La), aromaticity, number of (002) plane in carbon, and d-spacing. As a result, with increasing heat treat temperature of char, Lc$_{(002)}$, La$_{(10)}$ and number of (002) plane in carbon were increased, and d-spacing and FWHM(Full With Half Maximum) were decreased. Result of prediction of amount of char from the mixtures (char, coke and ore) based on the Lc$_{(002)}$ information of two mixtures (coke and char) showed very close values expected.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.227-235
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• 2003

The WSGG-based narrow band model was employed to solve the radiative transfer equations along isothermal and non-isothermal paths through $CO_2-H_2O-N_2$ gas mixtures at 1 atm. When the WSGGM is applied for arbitrary gas mixtures by considering the multiplication property of transmissivity in overlapping bands, the number of gray gases is significantly increased. To reduce the computation time, three different regrouping methods for the gray gases are tested in obtaining the mean absorption coefficient for each gray gas group. Among them, the regrouping method by minimizing the regrouping error shows the best results. For the isothermal media, 10 gray gases show fairly good agreement with the results by statistical narrow band(SNB) model which are regarded as reference solutions. For non-isothermal media, 20 gray gases show good agreement with reference solutions.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.85-94
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• 2011

Mixtures of sand and rubber particles ($D_{sand}/D_{rubber}=1$) are investigated to explore their characteristics under different stain level. Mixtures are prepared with different volumetric sand fractions ($sf=V_{sand}/V_{total}$). Experimental data are gathered from a resonant column, an instrumented oedometer, and a direct shear tests. Results show that sand and rubber differently control the behavior of the whole mixture with strain level. Non-linear degradation of small strain stiffness is observed for the mixtures with $sf{\geq}0.4$, while the mixtures with low sand fraction ($sf{\leq}0.2$) show significantly high elastic threshold strain. Vertical stress-deformation increases dramatically when the rubber particle works as a member of force chain. The strength of the mixtures increases as the content of rubber particle decreases, and contractive behavior is observed in the mixtures with $sf{\leq}0.8$. Rubber particle plays different roles with strain level in the mixture: it increases a coordination number and controls a plasticity of the mixture in small strain; it prevents a buckling of force chain in intermediate strain; it leads a contractive behavior in large strain.

• Journal of the Korean Institute of Landscape Architecture
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• v.23 no.2
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• pp.113-123
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• 1995

This study was conducted to find out appropriate rates of seed mixture of both native and foreign plants in order for stabilization of early afforestation and proper vegetation on road slope. The results are summarized as follows: 1. Characteristics of germination : After seeding, 2 weeks for both Lespedeza bicolor and Lespedeza cuneata, and 4 weeks for both Arundinella hirta and Zoysia japonica were needed for vigorous germination, and 1-4 wee17s for 3 cool-season grasses were spent for gradual germination. 2. Plant height : There was no difference between Lespedeza cuneata and Lespedeza bicolor in plant height by 7 treatments. As mixture rates of cool-season grasses were lowered, plant height of Arundinella hirta became longer. Descending order of co81-season grasses for plant height was Tall fescue, Perennial ryegrass and Creeping redfescue. 3. Number of tillers : The number of tillers tended to increase in the experimental plots where competition was low. 4 Ground cover rate : Ground cover rate was the highest in Mixture IV (96.7%) and was fluctuated from 13.3% on Sept. 13 to 45% on Nev. 3 in Mixture III. Descending order of gronud cover rates in 7 treaments was Mixture IV, Mixture III. Mixture II, Mixture Ⅶ, Mixture V, Mixture Ⅵ, Mixture I, and Mixtur III when measured on Oct. 13 5. Visual assessment: High preferences were observed on Mixture IV and Ⅶ In sun the best seed mixtures were Mixture IV and Ⅶ. It meant that (1) either mixture of 70% the native plants with 30% cool-season graaes or (2) mixture of 80% the native plants with 20% cool-season glasses was best for this study.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.23-32
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• 2011

To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.

• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.259-263
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• 1985

Rate Constants for the solvolysis of p-methylbenzyl chloride in various ethanol-water mixtures were studied at 30 and $40^{\circ}C$ under various pressures up to 1600 bar. The rates of reaction were increased with increasing temperature and pressure, and decreased with increasing solvent composition of ethanol mole fraction. From the rate constants, the values of the activation parameters (${\Delta}V^{\neq},{\Delta}{\beta}^{\neq},{\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$) were evaluated. The values of ${\Delta}V^{\neq}\;and\;{\Delta}{\beta}^{\neq}$ exhibit the extremum behavior at about 0.30 mole fraction of ethanol. This behavior is discussed in terms of solvent structure variation (electrostriction). From the relation between the reaction rate and the dielectric constant of solvent or the number of water molecule participated in the transition state, it could be postulated that the reaction proceeds through $S_N1$ mechanism.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1734-1737
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• 2015

Insulating characteristics of Cl₂-He mixture gases in gas discharges were analysed to evaluate ability of these gases for using in medium voltage and many industries. These are electron transport coefficients, which are the electron drift velocity, density-normalized longitudinal diffusion coefficient, and density-normalized effective ionization coefficient, in Cl₂-He mixtures. A two-term approximation of the Boltzmann equation was used to calculate the electron transport coefficients for the first time over a wide range of E/N (ratio of the electric field E to the neutral number density N). The limiting field strength values of E/N, (E/N)_lim, for these binary gas mixtures were also derived and compared with those of the pure SF₆ gas.

• Journal of the Korean Data and Information Science Society
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• v.23 no.2
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• pp.235-245
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• 2012

Logistic discrimination is an useful statistical technique for quantitative analysis of financial service industry. Especially it is not only easy to be implemented, but also has good classification rate. Generalized additive model is useful for credit scoring since it has the same advantages of logistic discrimination as well as accounting ability for the nonlinear effects of the explanatory variables. It may, however, need too many additive terms in the model when the number of explanatory variables is very large and there may exist dependencies among the variables. Mixtures of factor analyzers can be used for dimension reduction of high-dimensional feature. This study proposes to use the low-dimensional factor scores of mixtures of factor analyzers as the new features in the generalized additive model. Its application is demonstrated in the classification of some real credit scoring data. The comparison of correct classification rates of competing techniques shows the superiority of the generalized additive model using factor scores.

• Journal of KIEE
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• v.10 no.1
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• pp.7-15
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• 2000

Source separation is a statistical method, the goal of which is to separate the linear instantaneous mixtures of statistically independent sources without resorting to any prior knowledge. This paper addresses a source separation algorithm which is able to separate the mixtures of sub- and super-Gaussian sources. The nonlinear function in the proposed algorithm is derived from the generalized Gaussian distribution that is a set of distributions parameterized by a real positive number (Gaussian exponent). Based on the relationship between the kurtosis and the Gaussian exponent, we present a simple and efficient way of selecting proper nonlinear functions for source separation. Useful behavior of the proposed method is demonstrated by computer simulations.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.127-132
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• 2009

This study presents the test results on the compaction characteristics of warm mix asphalt mixtures that include the additive in 3 different mixtures(hot mix asphalt, SBS and SMA). The tests were conducted to find out the compaction characteristics on the compactability with varying compaction time, different amount of the warm mix additive and lowering the compaction temperature. The Superpave gyratory compactor was used to find out the variation of the density when the number of the gyration is varied. A dense mixture and 3 different warm mix additives were employed to find the relationship between compactability and compaction time. The comparison of the compactability with lowering the temperature was conducted using dense mixture, SBS polymer modified mixture and stone matrix asphalt mixture(SMA). The difference of the density of warm mix asphalt mixtures was not found due to the lowering of compaction temperature when it was compared with the standard mixture and the warm mix showed the stable condition in density. In the mean time, depending upon the different warm mix additive and mixture, the difference of density and the variation trend of compaction is found to be existed and shows the relationship between these two variables.