• 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.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.184-187
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• 2003

Complete prediction of second order permeability tensor for three dimensional circular braided preform is critical to understand the resin transfer molding process of composites. The permeability can be predicted by considering resin flow through the multi-axial fiber structure. In this study, permeability tensor for a 3-D circular braided preform is calculated by solving a boundary problem of a periodic unit cell. Flow field through the unit cell is obtained by using a 3-D finite volume method (FVM) and Darcy's law is utilized to obtain permeability tensor. Flow analysis for two cases that a fiber tow is regarded as impermeable solid and permeable porous medium is carried out respectively. It is found that the flow within the intra-tow region of the braided preform is negligible if inter-tow porosity is relatively high but the flow through the tow must be considered when the porosity is low. To avoid checkerboard pressure field and improve the efficiency of numerical computation, a new interpolation function for velocity variation is proposed on the basis of analytic solutions. Permeability of the braided preform is measured through a radial flow experiment and compared with the permeability predicted numerically.

• Journal of Soil and Groundwater Environment
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• v.25 no.2_spc
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• pp.55-69
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• 2020

Permeability-analyzing methods commonly involve small-scale drilling, such as pumping or slug test, but it is difficult to identify overall distribution of permeability of the entire target sites due to high cost and time requirement. Spectral induced polarization (SIP) method is known to be capable of providing distributions of both the porosity and the pore size, the two major parameters determining permeability of the porous medium. The relationship between SIP variables and permeability has been studied to identify the hydrological characteristics of target sites. Kozeny-Carman formula has been improved through many experiments to better predict fluid permeability with electrical properties. In this work, the permeability prediction techniques based on SIP data were presented in accordance with the hydrogeological and electrical characteristics of a porous medium. Following the summary of the techniques, various models and related laboratory experiments were analyzed and examined. In addition, the field applicability of the prediction model was evaluated by field case analysis.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.49-58
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• 2019

The effect of microstructure on the permeability of two saturated marine clays was studied through a series of falling head permeability tests and mercury intrusion porosimetry (MIP) tests. The key findings from this experimental study include the following results: (1) The permeability of undisturbed specimens is larger than that of reconstituted specimens at the same void ratio due to different soil fabrics, i.e., the pore size distributions (PSDs), even though they have the similar variation law in the permeability versus void ratio. (2) Different permeabilities of undisturbed and reconstituted specimens at the same void ratio are mainly caused by the difference in void ratio of macro-pores based on the MIP test results. (3) A high relevant relation between $C_k$ ($C_k$ is the permeability change index) and $e*_{10}$, can be found by normalizing the measured data both on undisturbed or reconstituted specimens. Hence, the reference void ratio $e*_{10}$, can be used as a reasonable parameter to identify the effect of soil fabric on the permeability of saturated soft clays.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.443-446
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• 2001

MI(Magneto-Impedance) sensor which is made by thin films has significantly high detecting sensitivity in weak magnetic field. It also has a merit to be able to build in low power system. Its structure is simple, which makes it easier to prepare a miniature. In this study, its magnetic permeability and anisotropy field(H$\sub$k/) as a function of a thickness of sputtered amorphous CoZrNb thin film with high saturation magnetostriction and excellent soft magnetic property are investigated. In order to make a uniaxial anisotropy, thin film was subjected to post annealing with a static magnetic field with 1KOe intensity at 250, 300, and 320$^{\circ}C$ for 2 hour. Anisotropy field(H$\sub$k/)of thin film is measured by using MH loop tracer. Its magnetic permeability of thin film is measured over the frequency range from 1 MHz to 750MHz. It has shown that the magnetic permeability of amorphous CoZrNb thin film is decreased due to the skin effect with increasing a thickness of CoZrNb thin film, and hence its driving frequency is lowered.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.98-105
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• 1997

Compacted clay materials are often used to form barriers for waste disposal by means of landfill. The performance of clay barrier depends on its permeability characteristics under the site environments. The study discusses permeability characteristics of 4 types of permeants through a compacted clayey soil. Permeabilities are measured using the modified rigid-wall permeater and with water, PEG, Ethanol, and TCE, ranging 80 to 3.4 of dielectric constants. Results of the study are as follows : 1) Absolute permeabilities of Ethanol and TCE that their dielectric constants are lower than that of water are $K=1.0{\times} 10^{-12} cm^2$, and $5.8{\times} 10^{-12} cm^2$, respectively, that is, 1.67, and 9.67 times of permeability of water, respectively. Absolute permeability and dielectric constant of water are $K=6{\times} 10^{-13} cm^2$, and 80, respectively. 2) Changes in absolute permeability of Ethanol and TCE converge to a constant after 3.5 pore volume of permeant flows through the clay sample. This can be explained that diffuse double layer of clay is no longer reacted with permeants and contracted their pores. However there is no change in absolute permeability when water is used as a per-meant. 3) It is found that absolute permeability in reversely proportional to the value of dielectric constant of the permeants. Change in absolute permeability of the permeants with 40 or over of dielectric constant is not significant. However change in absolute permeability of the permeant with 30 or lower dielectric constant is abruptly increased. 4) A lower absolute permeability of PEG is found because of its high viscosity.

• Journal of Magnetics
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• v.1 no.1
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• pp.24-30
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• 1996

The relationship between effective permeability and the remanence ratio of an Fe-based amorphous alloy (Metglas 2605S3A) is investigated over a wide frequency range, in an effort to understand magnetization behavior of the alloy. In the frequency range from 1 to 200 kHz, the permeability is maximum at the remanence ratio of 0.4-0.5 and, at frequencies over 500 kHz, the correlation with negative coefficients emerges indicating that the permeability decreases with the remanent ratio, except for the ribbon coated with an insulating layer of MgO which exhibits both high values of the effective permeability and remanence ratio. It is considered from the correlation results that the boundary at which the dominant magnetization mechanism changes from domain wall motion to spin rotation is near 500 kHz. The core loss is also investigated as a function of annealing time when the samples are annealed at a fixed temperature of $435^{\circ}C$. The core loss in most cases decreases with the annealing time, the degree of the loss may consist of the hysteresis loss and anomalous eddy current loss. The two loss components are considered to be of similar magnitudes at low frequencies while, at high frequencies, the dominant contribution to the total loss is the anomalous loss.

• Membrane Journal
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• v.29 no.4
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• pp.191-201
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• 2019

Before the commercialization of polymeric membranes applicable for industrial application, the homework remains for the high-performance polymers to overcome the practical challenge: long-term stability for prolonged service time. Polymers of intrinsic microporosity (PIMs), exhibiting exceptionally high fractional free volume and high permeability, are susceptible to physical aging where the extra volume created by the inefficient ladder-type packing will lead them from the volumetric equilibrium and reduce the free volume/permeability over time. Here, we will re-examine the physical aging of polymers of intrinsic microporosity, and discuss some of the most prominent attempts to mitigate physical aging in PIMs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.2157-2163
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• 2009

The oxygen permeability of a soft contact lens is an important parameter for determining corneal health when considering the physiological response of the eye. The aim of this study is to evaluate the oxygen permeability of soft contact lenses based on thickness, using the polarographic method. The thickness of lens was measured using contact and non-contact method. To assess accuracy and reliability, the Bland-Altman plot was used. The reliability was high for the oxygen permeability based on center thickness measured by contact method, whereas the accuracy was high for the oxygen permeability based on center thickness measured by non-contact method. These results indicate that the permeability characteristics were variable according to the measurement and criteria of thickness of soft contact lenses and the measurement of soft contact lenses by non-contact method was more reasonable. Thus, contact lens practitioners should consider some basic differences between methodologies when interpreting or quoting oxygen performance data.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.131-139
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• 2000

Porous Concrete usually contains large amount of voids(about 10∼20%) after compaction so that it has relatively high permeability. It has been introduced in domestic since early 1980's but it has problems such as lack of optimized mixture, low strength and durability, and other defects, etc. The purpose of this study is to manufacture high-performance porous concrete using polymer to enhance the mechanical properties. The results of this study are as follows; the compressive strength range 12 92∼207kgf/㎠, the tensile strength range is 14∼28kgf/㎠, the bending stength range is 42∼73kgf/㎠, and the coefficient permeability range is 5.77×10-2∼6.79×10-1cm/sec. To develope high-performance porous concrete. further studies are needed on optimum mixture of fineness modulus and admixture.