• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.415-422
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• 1999

A series of crosshole tests was conducted to evaluate the mechanical characteristics of railway subgrade materials which has been experiencing mud-pumping. The shear wave velocity profiles of mud-pumped sites were compared with those of adjacent intact sites. The shear wave velocities of mud-pumped layers are less than 150 m/sec.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.987-993
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• 2004

The status of mud-pumping in the existing railroad lines were investigated and real-scale tests simulating mud-pumping phenomena were carried out to analyze its mechanism. The penetration of ballast material into the subgrade and the cause of mud-pumping are explored. The results of the investigation and tests will be used to develop the new method and materials for the prevention of mud-pumping.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.81-82
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• 2018

In this paper, we investigate the characteristics of wet soil concrete according to the addition ratio of liquefaction red mud addition rate by liquefying red mud. as a result, the compressive strength decreased and the water absorption ratio increased as the liquefaction red mud addition rate increased.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.267-276
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• 2005

The study is to determine the feasibility of activated red mud as an anti-red tide material. The red mud, a byproduct of Bayer process for the production of alumina from bauxite, contained hematite, boehmite, calcite, sodalite, quartz, zircon, anatase and an unknown phase. In the adsorption study of the red mud, its adsorption efficiencies for heavy elements were close to $100\%$ except $92\%$ In As. These results seem to be attributed by the high adsorption ability of iron oxides for heavy elements. As a result of leaching tests with the red mud at various pHs (pH $1\∼13$), the high leaching efficiencies for As, Cu and Zn at low pHs (at acidic condition) were obtained. It indicated that removal efficiency of heavy elements could be excellent in acidic treatment of red mud. The activated red mud, red mud reacted with acid, contained hematite, boehmite and so on, and desorption of heavy metals from the activated red mud increased with increasing temperature. The grain of the activated red mud was tens nm in size. The removal efficiency for 5 types of plankton was generally in inverse proportion to pH, especially to final pH. Of five plankton types, Prorocentrum minimum and Alexandrium tamarense promptly were removed more than $90\%$ as soon as the activated red mud was sprayed and $100\%$ after 30 minutes. These results indicated that the activated red mud seems to be a promising anti-red tide material.

• The Journal of the Acoustical Society of Korea
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• v.23 no.4E
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• pp.140-145
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• 2004

A laboratory study was carried out to investigate the change of ultrasonic velocity as a function of temperature for fluid mud (i.e., suspension). Pulse transmission technique with ultrasonic wave was used for ultrasonic velocity measurement. The five samples for fluid mud were prepared for concentration range of $30.6{\%}\;(1.24\;g/cm^{3}\;in\;density),\;23.3{\%}\;(1.19\;g/cm^{3}),\;11.5{\%}(1.10\;g/cm^{3}),\;7.8{\%}\;(1.08\;g/cm^{3}),\;and\;3.8{\%}\;(1.05\;g/cm^{3})$ by weight. The ultrasonic velocity in fluid mud was investigated to increase $(approximately\;2.83\;to\;4.95\;m/s/^{\circ}C)$ with increasing temperature, due to the effect of viscosity and compressibility of water with changing temperature. But the increasing rate tends to decrease at temperature higher than $30^{\circ}C,$ caused by the effect of viscosity. The concentration of fluid mud more affect to the ultrasonic velocity at higher temperature range than that at lower temperature. Overall the temperature effect on the ultrasonic velocity in fluid mud was a similar rate as for distilled water and seawater, suggesting fluid mud significantly depends on the behavior of water.

• Journal of the Korean GEO-environmental Society
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• v.9 no.7
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• pp.37-43
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• 2008

The unconfined compressive strength of soil-cement mixed with red mud, an industrial by-product of alumina production, was investigated in the laboratory. The investigation involved laboratory tests under the various conditions such as red mud content, cement content, fly ash content and ratio of soil replacement with sands. The unconfined compressive strength tests were performed at 7, 14 and 21 days after specimen preparation. Results of the study show that the unconfined compressive strength increased as red mud and fly ash content decreased and cement content increased. Increasing the soil replacement ratio with sands had an insignificant effect on compressive strength because the soil had a similar particle size as the replacement sands.

• Animal cells and systems
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• v.3 no.4
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• pp.407-412
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• 1999

The influence of eating habits and food type on the ultrastructural characteristics of the digestive tracts was studied under the scanning and transmission electron microscopes in two crustacean decapods (Hemigrapsus penicillatus De Haan; mud crab, Pinnotheres cyclinus Shen; symbiotic crab). The relative ratio of the length of midgut versus hindgut was 1:1 in the mud crab, but 4:1 in the symbiotic crab. Observation through the scanning electron microscope revealed that the midguts of both species have densely-arranged longitudinal mucosal folds with a smooth surface. In the hindgut of the mud crab, mucosal folds were longitudinally oriented, clusters of two to five spines were observed on the cuticular surface, and the length of the spine in the distal hindgut was longer than that in the proximal portion. In the symbiotic crab, the mucosal folds were irregulary arranged, and numerous rudimentary spinal structures were noted on the cuticular surface. Through observation of a transmission electron microscope, the epithelial cells of the midgut in both species had numerous microvilli, but the length of the microvilli was slightly longer in the mud crab than in the symbiotic crab. The central layer of the basement membrane and the muscular layer of the midgut were more developed in the mud crab than in the symbiotic crab. The thickness of the cuticular layer over the hindgut surface in the mud crab was about 4 times than that of the symbiotic crab.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2C
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• pp.91-99
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• 2003

In this paper, We analyze performance of ZFE MUD receiver in DSSS unidirectional wireless transceiver operating in 2.4㎓ ISM band and indoor environment. This system has the shortcomings that many burst error is occurred because of long term deep fade experienced by some user and impossibility of power control. Therefore, the solution to this problem is important because the performance of DS-CDMA system is guaranteed under, the perfect power control. MUD receive. which improves the performance of this system is not required to perform rigorous power control and is able to remove MAI using linear equalization. From the result of performance comparison, we show that ZFE MUD receiver is more adequate for this system than other receivers.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.183-194
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• 2017

When a borehole is drilled, the load distributed by the removal is taken to re-establish equilibrium. As a result, the stresses around the borehole is redistributed. If there is no hydrostatic support pressure by drilling fluid (mud) introduced into the borehole, failure in the formation may take place. The mud pressure boundary that keeps the borehole stable is defined as a mud window. To predict the potential for failures around the borehole, a series of numerical analysis were performed and compared with a mud window. The effect of failure criterion and the intial stress ratio adopted on the mud window was also studied.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.146-152
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• 2018

In the construction sector, new demands for aesthetics are increasing due to structural stability and improvement of living standard and consciousness level. On the other hand, Red Mud sludge is generated from aluminum hydroxide extraction process from Bauxite. Red mud sludge contains about 20% of $Fe_2O_3$ and represents a natural reddish brown. It is highly applicable to the construction industry. In this paper, red mud sludge with a water content of 50%, which is a by - product of the industry, was prepared as a liquid phase. The liquefied red mud was added to cement mortar and the strength and color difference of cement mortar were investigated according to the addition amount of liquefied red mud. As a result, the compressive strength decreased with increasing amount of liquefied red mud. The color of cement mortar containing liquefied red mud was found to be distributed in the range of YR series in all samples. As the amount of liquefied red mud increased, the color became darker.