• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.33-42
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• 2013

In this paper, a series of monotonic undrained shear tests were carried out on four kinds of sand-fine mixtures with various fines content. Two kinds of sands (Silica sand V3, V6) and fines (Iwakuni natural clay, Tottori silt) were mixed together in various proportions, while paying attention to the void ratio expressed in terms of sand structure $(F_c{\leq}F_{cth})$. The undrained shear strength of mixtures below the threshold fines content was observed so that as the plastic fines content increases, maximum deviator stress ratio decrease for dense samples while an increase is noted for loose samples. For non-plastic fines, the increase in the amount of fines leads to an increase in density of the soil, which results in an increase in strength. Then, the monotonic shear strength of the mixtures was estimated using the concept of granular void ratio. It was found that the shear strength of mixtures is greatly dependent on the skeleton structure of sand particles.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1819-1823
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• 1997

When flammable gases are mixed with air or oxygen in the explosion concentration range and are ignited by sufficiently large electrostatic discharge energy, they may explode causing severe disaster in workplaces. The minimum ignition energy (MIE) of single gas-air mixtures has been already investigated by many researchers, but the MIE of mixtures of more than three substances is not examined yet. The purpose of this study is to investigate the MIE of several three-component gas mixtures experimentally. The result of our experiment shows that the MIE of some gas mixtures is quite different from that we expected based on the characteristics of individual gas-air mixture.

• Journal of the Korean Ceramic Society
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• v.31 no.3
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• pp.337-345
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• 1994

The reaction-sintered alumina and zirconia-alumina ceramics having low firing shrinkage were prepared from the Al/Al2O3 or Al/ZrO2(Ca-PSZ) powder mixtures via the attrition milling. And in this milling process the effect of the characteristics of used powders was investigated. Attrition milling was much more effective in reducing the particle size of ceramic/metal mixed powders than ball milling. Powder mixtures of flake-type Al with coarse alumina was much more effectively comminuted by the attrition milling than the mixtures of globular-type Al with coarse alumina powders. And coarse alumina than fine alumina was much more beneficial in cutting and reducing the ductile Al particles. In the contrary to Al/Al2O3 powder mixtures, Al/ZrO2 powder mixtures was not effectively comminutd. But whether using the alumina ball media or attrition milled with Al2O3 powder rather than Al, the milling efficiency was much more increased.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.953-956
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• 2002

Excess molar volumes (Vm E ) of binary liquid mixtures: xC6H5CH3 + (1-x1)CH3CN or + (1-x1)C6H5NO2, or + (1-x1)C2H5NO2 have been determined as a function of mole fraction of C6H5CH3 (x) at a temperature of 303.15 K over a entire range of composition. The densities of the binary liquid mixtures were determined by pycnometrically. The VmE values of the mixtures have been found to be negative over the whole composition in order of C6H5CH3 + C6H5NO2, < C6H5CH3 + CH3CN, and < C6H5CH3 + C2H5NO2. The negative magnitude of VmE suggests the presence of intermolecular interaction in the three binary liquid mixtures.

• Biomedical Science Letters
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• v.17 no.1
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• pp.47-53
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• 2011

This study is aimed to investigate the skin thickness, plasma components, serum IgE level and antioxidant enzymes activities by mixtures of Cnidium officinale, Saururus chinensis, Houttuynia cordata and Glycyrrhiza uralensis on the allergic contact dermatitis of rat induced by 1-chloro-2,4-dinitrochlorobenzene (DNCB). Mixtures reduced the thickness of the skin and removed the dead skin cells compared to the skin of rats treated with DNCB alone. Also, these mixtures down-regulated the contents of lipid and IgE, and reduced the activities of superoxide dismutase and catalase. These results indicate that the mixtures significantly recovered the contact dermatitis induced by DNCB. In conclusion, it is thought that the mixtures could be useful for the allergic contact dermatitis.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.92-96
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• 1995

The flash point is generally used as a hazardous index of fire or explosion of a flammable liquid. In this study, the lower flash points and the upper flash points according to the composition of Toluene-o-Xylene and Toluene-Methyl Ethyl Ketone mixtures are determined by air-blowing method. As results, relations between the flash points and the compositions of mixtures ; (1) for Toluene-o-Xylene mixtures $T_{fL}$=25.23 $\alpha$ ＋5.34 $T_{fu}$=27.36 $\alpha$ ＋40.50 (2) for Toluene-Methyl Ethyl Keton mixtures $T_{fL}$=10.00 $\beta$-5.00 $T_{fu}$=16.91 $\beta$＋20.45.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.03a
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• pp.69-90
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• 1996

In the chemical industry, in the pharmaceutical industry, and in a number of other industries separation processes are necessary to separate and purify products and raw materials [1,2]. Separation processes are also widely used in other applications such as in recycling valuable materials from waste streams. Unit operations for separation processes can be classified in phase separation techniques and component separation techniques based on the nature of the feed mixtures to be separated. The former techniques are used for the separation of heterogeneous mixtures, in which the feed is already present in two or more separated phases on a micro-scale. The latter are suitable for the separation of homogeneous mixtures such as gaseous mixtures and mixtures of completely miscible liquids. tn these cases the separation into individual components is generally achieved by utilizing the differences in physico-chemical properties of components, and is much more difficult compared to phase separation techniques. Separation processes such as distillation, evaporation, liquid-liquid extraction, and crystallization belong to this class.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.5
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• pp.342-350
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• 2008

This paper presents the results of a laboratory study on the thermal conductivity of sand (silica, quartzite, limestone and masonry sand)-water mixtures used in ground heat exchanger backfilling materials. Nearly 150 tests were performed in a thermal conductivity measuring system (TPSYS02) to characterize the relationships between the thermal conductivity of mixtures and the water content. The results show that the thermal conductivity of mixtures increases with increasing dry density and with increasing water content. The results also show that for constant water contents and a dry density value, the thermal conductivity of mixtures increases with increasing thermal conductivity of solid particles. The measurement results were also compared with the most widely used empirical prediction models for the thermal conductivity of soils.

• Journal of Information Display
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• v.2 no.3
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• pp.32-38
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• 2001

The most important parameter for TV application of LCD is a fast switching time for the display of moving image. To achieve faster switching time, the novel LC single materials with large dielectric anisotropies ($16{\sim}20$), high clearing temperatures ($195.5{\sim}237.4^{\circ}C$), broad nematic ranges (up to 169.9 $^{\circ}C$) and high birefringence ($0.254{\sim}0.2200$) were developed. KUR-series LC mixtures blended these single materials having significantly higher clearing temperatures and dielectric anisotropy values compared with conventional LC mixture. Especially, their clearing temperatures are $10{\sim}30^{\circ}C$ higher than their host mixture. These LC mixtures showing about lOms of high-speed switching time in Tv/Monitor of TFT LCD, is short enough to be addressed in a single time frame of 60Hz (16.7 ms). The threshold voltage $V_{th}$ was low enough to operate at a driving voltage of 5 V. The VHR values were found to be high enough for TFT-LCD in wide temperature range. Our novel LC mixtures are suitable materials for the inclusion in to LC mixtures for TV application of TN-LCD

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.419-426
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• 2000

The purpose of this study is to present the application of WFS co-mixtures for retaining wall as flowable backfill. The fly ash, generated at the Tae-An thermoelectric power plant, was used in this research and was classified as Class F. Green Sand, Furane Sand, and Coated Sand, which had been used at a foundry located in Pusan, were used. Couple of laboratory tests and small scale retaining wall tests were performed to obtain the physical properties of the WFS co-mixtures and the possibility of backfill materials of retaining wall. The range of permeability for all the co-mixtures was from 3.0${\times}$10$\^$-3/ cm/s to 6.0${\times}$10$\^$-5/ cm/s. The unconfined strength of the 28-day cured specimens reached around 550kPa. Results of the consolidated-undrained triaxial test showed that the internal friction angle is between 33.5$^{\circ}$ and 41.8$^{\circ}$. The lateral earth pressure against wall decreased up to 80% of initial pressure within a 12 hours and the total lateral earth pressure is less than that of typical granular soil. It was enough to construct the backfill for the standard retaining of 6m with just two steps, like fill the co-mixtures for half of retaining wall, and then fill the others after 1 day. The stability of retaining wall for overturning and sliding increased as the curing time elapsed.