• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.1
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• pp.37-46
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• 1999

Water vapor permeability of films is commonly calculated from the water vapor transmission rate of the film measured using a permeability cup method which is essentially a gravimetric method. This method was originally developed for petroleum based plastic films with low water vapor permeability. In the case of hydrophilic bio-polymer films, the resistance caused by a stagnant air layer, which is developed between the underside of the film mounted on the cup and the surface of the desiccant saturated salt solution or distilled water, can be significant and, if neglected, ran lead to underestimation of water vapor transmission rates. Therefore, it is necessary to correct water vapor transmission rate data to accurately estimate the water vapor permeability of bio-polymer films.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.3
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• pp.3815-3832
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• 1975

This study was made to investigate various engineering properties of earth materials resulting from their changes in density and moisture content. The results obtained in this study are summarized as follows: 1. The finner the grain size is, the bigger the Optimum Moisture Content(OMC) is, showing a linear relationship between percent passing of NO. 200 Sieve (n) and OMC(Wo) which can be represented by the equation Wo=0.186n+8.3 2. There is a linear relationship of inverse proportion between OMC and Maximum Dry Density (MDD) which can be represented by the equation ${\gamma}$d=2.167-0.026Wo 3. There is an exponential curve relationship between void ratio (es) and MDD whose equation can be expressed ${\gamma}$d=2.67e-0.4550.9), indicating that as MDD increases, void ratio decreases. 4. The coefficent of permeability increases in proportion to decrease of the MDD and this increase trend is more obvious in coarse material than in fine material, and more obvious in cohesionless soil than in cohesive soil. 5. Even in the same density, the coefficient of permeability is smaller in wet than in dry from the Optimum Moisture Content. 6. Showing that unconfined compressive strength increases in proportion to dry density increase, in unsaturated state the compacted in dry has bigger strength value than the compacted in wet. On the other hand, in saturated state, the compacted in dry has a trend to be smaller than the compacted in wet. 7. Even in the same density, unconfined compressive strength increases in proportion to cohesion, however, when in small density and in saturated state, this relationship are rejected. 8. In unsaturated state, cohesion force is bigger in dry than in wet from OMC. In saturated state, on the other hand, it is directly praportional to density. 9. Cohesion force decreases in proportion to compaction rate decrease. And this trend is more evident in coarse matorial than in fine material. 10. Internal friction angle of soil is not influenced evidently on the changes of moisture content and compaction rate in unsaturated state, On the other hand in saturated state it is influenced density. 11. Cohesion force is directly proportional to unconfined compressive strength(qu), indicating that it has approximately 35 percent of qu in unsaturated state and approximately 70 percent of qu in saturated state.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.1
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• pp.52-61
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• 2000

Permeability is important factor in the geotechnical problems, such as seepage discharge and dissipation of excess pore water pressure. The Kozeny-Carman equation works well for graded soils but serious discrepancies are found in clays. Major factor for these discrepancies is the tortuous flow path and unequal pore size. To estimate the permeability of fine grained soils, a permeability equation in which swelling potential is coupled with Kozeny-Carman equation is proposed in this study. To verify proposed equation, a series of variable head permeability test was carried out for steel making slag and sludge mixed with bentonite. The coefficients of permeability which is measured in the laboratory is compared with the values by the proposed equation. From the comparison, it is shown that the proposed equation can predict the coefficient of permeability of clays with satisfaction. As steel making slag and sludge is industry waste, it is reused as material of road foundation and cement but the rate of use is low. It mixed sodium-bentonite with high swelling property and permeability decrease effect. Then, Admixture investigates reuse possibility as liner of waste fill.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.9-17
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• 2009

Most of the current drainage criteria have been developed on the basis of experimental field results and theoretical analyses of infiltration under saturated conditions. The objective of this study is to extend the understanding of pavement drainage systems by considering unsaturated condition in the sublayers. Analyses of unsaturated flows through pavements was performed by running finite element program(SEEP/W) with a range of pavement materials and drainage parameters. Meanwhile, the widely used DRIP program developed by FHWA is based on assumption of saturated condition of pavements. Differences between saturated and unsaturated condition in the sublayers of the pavements are verified. It is verified that for unsaturated conditions time to drain would take longer time compared to saturated condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.538-548
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• 2003

We studied effects by Re$_2$O$_3$(R=Dy, Gd, Ho) addition on the properties of Mn-Zn ferrite. The doping concentration range from 0.05 wt% to 0.25 wt%. All samples were prepared by standard fabrication of ceramics. With increasing the rare earth oxides, specific density and initial permeability increased on the whole. But, the tendencies such as upper result had the measured value on limitation and characteristics saturated or decreased properties after that. In case of excessive addition of additive beyond some level, initial permeability properties of ferrite have gone down in spite of anomalous grain. With increasing the content of additive, both the real and imaginary component of complex permeability and the magnetic loss (tan$\delta$) increased. Because the increased rate of real component had higher than imaginary component, magnetic loss increased none the less for increasing the real component related with magnetic permeability. But, the magnetic loss of ferrite doped with the rare earth oxides was lower than that of Mn-Zn ferrite at any rate. The small amount of present rare earth oxides in Mn-Zn ferrite composition led to enhancement of resistivity in bulk, and more so in the grain boundary. It was seem to be due to the formation of mutual reaction such as between iron ions and rare earth element ions.

• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.57-64
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• 2013

In this paper, in order to solve high water content of water sludge and promote its recycle, sludge mixtures with various mixing ratios were produced. Sludge mixture consisted of water sludge and weathered granite soil. Their physical properties and unsaturated characteristics (soil-water characteristic curve, and unsaturated permeability function) were investigated by laboratory tests. Experimental test results indicated that at a given matric suction volumetric water content of sludge mixture increased as water sludge content increased. Air entry values of sludge mixture increased from 0.9 kPa to 2.4 kPa with an increase in water sludge content or fine content. In addition, unsaturated permeability function, which is an important factor for performing infiltration analysis, was predicted using saturated permeability and soil-water characteristic curve of sludge mixture.

• Geomechanics and Engineering
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• v.4 no.2
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• pp.91-103
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• 2012

Focusing on the effect of excess pore pressure dissipation on liquefaction-induced ground deformation, a series of 1-g shaking table tests were conducted in a rigid soil container by use of saturated Toyoura sand, the relative density of which was 20-60%. These tests were subjected to the sinusoidal base shaking with step increased accelerations: 100, 200, 300 and 400 Gals for 2-4 seconds. Shaking table tests were done using either water or polymer fluid with more viscous than water, thus varying the sand permeability of model tests. Excess pore pressures, accelerations, settlements and lateral deformations were measured in each test. Test results are presented in this paper and the effect of sand permeability on liquefaction and liquefaction-induced ground deformation was discussed in detail.

• Korean Journal of Materials Research
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• v.32 no.3
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• pp.115-124
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• 2022

Porous basalt aggregate is commonly used in roadbed engineering, but its application in concrete has rarely been studied. This paper studies the application of porous basalt in concrete. Porous basalt aggregate is assessed for its effects on mechanical strength and durability of prepared C50 concrete; because it has a hole structure, porous basalt aggregate is known for its porosity, and porous basalt aggregates can be made full of water through changing the content of saturated basalt; after full-water condition is achieved in porous basalt aggregate mixture of C50 concrete, we discuss its mechanical properties and durability. The effects of C50 concrete prepared with basalt aggregate on the compressive strength, water absorption, and electric flux of concrete specimens of different ages were studied through experiments, and the effects of different replacement rates of saturated porous basalt aggregate on the properties of concrete were also studied. The results show that porous basalt aggregate can be prepared as C50 concrete. For early saturated porous basalt aggregate concrete, its compressive strength decreases with the increase of the replacement rate of saturated aggregate; this occurs up to concrete curing at 28 d, when the replacement rate of saturated basalt aggregate is greater than or equal to 40 %. The compressive strength of concrete increases with the increase of the replacement rate of saturated aggregate. The 28 d electric flux decreases with the increase of the replacement rate of saturated aggregate, indicating that saturated porous basalt aggregate can improve the chloride ion permeability resistance of concrete in later stages.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.159-170
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• 2021

Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.433-452
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• 2018

The shield tunneling method can minimize surface settlements by preventing the deformation of tunnel face and tunnel intrados due to tunnel excavation. For this purpose, it is very important to control the operating conditions of shield TBM. The face pressure and backfill pressure for tail void grouting should be the most important and immediate measure not only to restrain surface settlement, but also to influence the effective stress and pore water pressure around the circumstance of tunnel during excavation. The reaction of the ground to the application of face pressure and backfill pressure relies on the stiffness and permeability of ground. Especially, the reaction of saturated clayey ground formations, which shows the time-dependent deformation, is different from the permeable ground. Hence, in this paper it was investigated how the TBM operating conditions, ground stiffness, and permeability impact on the surface settlement of saturated clayey ground. For this purpose, a series of parametric studies were carried out by means of the stress-pore water pressure coupled FE analysis. The results show that the settlement of soft clayey ground is divided into the immediate settlement and consolidation settlement. Especially, the consolidation settlement depends on the ground stiffness and permeability. In addition, the existence of critical face pressure and backfill pressure was identified. The face pressure and backfill pressure above the critical value may cause an unexpected increase in the ground settlement.