• Korean Journal of Materials Research
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• v.16 no.9
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• pp.578-583
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• 2006

We studied the physical properties of Ni-Zn ferrites by adding different chemicals such as $SO_4$, Cl, and $NO_3$. Specimens were prepared by the coprecipitation method and sintered at temperatures $950^{\circ}C,\;1,150^{\circ}C,\;and\;1,350^{\circ}C$, respectively. X-ray diffractions showed a spinel structure and the optical microscopy revealed grain size of 0.3 to 0.6 ${\mu}m$. The optimum sintering temperature to obtain fine, sintered microstructure depended on the additive : Cl and $NO_3\;at\;950^{\circ}C\;and\;SO_4\;at\;1,150^{\circ}C$. According to particle size analysis, higher magnetic permeability and magnetization value were observed with Cl and $NO_3\;than\;SO_4$. As sintering temperature was raised from $950^{\circ}C$ to $1,350^{\circ}C$, the average grain diameter, initial permeability and the magnetic moment also increased.

• Journal of the Korean Home Economics Association
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• v.17 no.4
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• pp.23-28
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• 1979

In order to measure the change of constructional and some properties of knitted under wears by laundry, constructional properties, such as fabric count , yarn count, loop length and cover, factor, and some properties , such as shrinkage, tearing, strength, air permeability, electrostatic charge of under wears sold in the market were tested. The results of the experiment can be summarized as follows.1. Interlock and rib were increased in wale direction after laundry and decreased in course direction , plain was decreased, in both direction after laundry. 2. Loop form of plain was changed more than those interlock and rib after laundry. 3. Tearing strength was decreased 51% in wale direction, and 70% in course direction after 20 times laundry. Air permeability was generally increased. 4. Electro static charge was increased 9 times after laundry.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.149-156
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• 2020

Permeation grouting effectively enhances soil strength and decreases permeability of soil; however, the flow of grout is heavily affected by anisotropy of hydraulic conductivity in layers. Therefore, this study investigates the effect of permeability anisotropy on the effective radius of horizontal permeation grout using computational fluid dynamics (CFD). We modeled the horizontal permeation grout flow as a two-phase viscous fluid flow in porous media, and the model incorporated the chemical diffusion and the viscosity variation due to hardening. The numerical simulation reveals that the permeability anisotropy shapes the grout bulb to be elliptic and the dissolution-driven diffusion causes a gradual change in grout pore saturation at the edge of the grout bulb. For the grout pore saturations of 10%, 50% and 90%, the horizontal and vertical radii of grout bulb are estimated when the horizontal-to-vertical permeability ratio varies from 0.01 to 100, and the predictive model equations are suggested. This result contributes to more efficient design of injection strategy in formation layers with permeability anisotropy.

• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.47-54
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• 2011

Consolidation behavior of soft clay is generally to be affected by its compressibility and deformation characteristics. Especially, soil permeability depends on soil characteristics including its type of anisotropy. Coefficient of permeability of soft clay is mostly estimated by using laboratory(Oedometer test) and in-stiu piezocone test. The permeability characteristics of soft clay is estimated by excess pore pressure dissipation test results. In this study, the tests were performed to find out the validity of the existing theoretical formula in clay by pore pressure dissipation test and laboratory test results. After grasping of variation the coefficient of permeability ratio(${k_{h}/k_{v}}$) in different clay soils, it was found out adequate solution of in-stiu permeability ratio(${k_{h}/k_{v}}$). Piezocone tests and laboratory tests were performed at the site of pilot project of ground improvement at Yangsan-Mulgeum, Gyeongsangnam-do. Comparisons of the estimated values of ${k_{h}/k_{v}}$ using piezocone tests results and those from laboratory consolidation tests were carried out. Test results show that values of ${k_{h}/k_{v}}$ by piezocone test result(5.85) is similar of it's laboratory test(5.28).

• Resources Recycling
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• v.21 no.5
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• pp.38-43
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• 2012

In this study, analysis of the flow of water in the soil environment was attempted to examine the changing patterns of permeability coefficient, k, presented in Darcy's law depending on soil particle size and the pattern of mixed soil that main factor affecting ground water flow in soil environment. In addition, permeability coefficient patterns depending on changes in water temperature and concentration were measured. As a result, the permeability for the soil particle size and mixing pattern is proportional to the size of the particles, and it was also influenced by the porosity depending on the mixed pattern and stratification. Especially compared with the single particle, mixing different sizes samples showed a lower k than the value of smaller single particles. In addition, permeability of groundwater increased with increasing temperature, also permeability decreased depending on the concentration of ions in groundwater. The results of this study were expected to use as meaningful data for the phenomenon reflects the characteristics of the soil to understand mobility of groundwater in soil environment.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.69-81
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• 2001

The constitutive relation among capillary pressure, saturation and relative permeability should be predetermined in order to simulate immiscible water-gas flow in porous media. The relation between saturation and relative permeability becomes more important when the capillary force can be disregarded and viscous friction force governs the flow. In this study, a 2-dimensional finite difference numerical model was developed, in which the variation of viscosity with pressure and that of relative permeability with water saturation can be treated. Seven cases of parallel plate tests were performed in order to obtain the characteristic equation of relative permeability which would be used in. the developed numerical model. It was not possible, however, to match the curves of relative permeability from the plate tests with the existing emperical models. Consequently a logistic equation was proposed as a new emperical model. As this model was composed of the parameter involving aperture size, any aperture size of fracture can be applied to the model. For the purpose of verification, the characteristic equation of relative permeability was applied to the developed numerical model and the computed results were compared with those of plate test. As a result of application of numerical model, in order to check the field applicability, to single fracture surrounding an underground storage cavern, the simultaneous flow of water and propane gas was able to be simulated properly by the model.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.137-146
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• 2010

To estimate the accumulated infiltration, Horton's and Green-Ampt's equations are usually applied. Because the real infiltration is penetrated into the soil continuously, to cover the problems of the conventional equations derived from the discontinuous infiltration system, new infiltration equation is derived from the concepts of continuous infiltration system. Furthermore, infiltration tests were done to compare the results from the conventional Horton's and Green-Ampt's equations and newly derived equation. Unsaturated permeability is the function of water content ratio or saturation degree, which affects directly to the infiltration capacity and accumulated infiltration. Therefore, the variation term of unsaturated permeability is inserted into the new equation to estimate the proper infiltration capacity and accumulated infiltration. It will make the more accurate analysis for the safety of structure and the behavior of groundwater.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2229-2233
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• 2015

The permeability of HMA(hot mixed asphalt) is a major influencing factor for long-term performance of the pavement. Especially, the lift thickness of the pavement during construction causes a wide range of physical properties of HMA. This study investigates the correlationship between the lift thickness and the physical properties of HMA through a series of laboratory experiments. The specimens were cored from a construction site of the dense graded asphalt pavement. The cored samples have various lift thickness and the number of compaction for the study. The results of the study show that the permeability of the sample decreases with the apperant density and t/NMAS, and the air void ratio. Therefore, the commonly used construction method as a constant lift thickness regardless of conditions needs to be reconsidered.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.273-273
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• 1996

Recently a novel in vivo approach in dogs, using a regional segmental intestinal perfusion technique, has been developed. The perfusion tube consists of a highly sophisticated multichannel tube with two inflatable occluding balloons, which are placed in 10cm apart. The tube was introduced orally from the stomach through the upper jejunum under the guidance of solid-state pH meter. In the present study, four healthy dogs were infused in the proximal jejunum on two periods. The two perfusion experiments used the same flow rate, 2 $m\ell$/min, and the same perfusion solution to determine the intrasubject variability. The mean (${\pm}$ S. E.) fractions of ranitidine absorbed calculated from the perfusion data were 21.32${\pm}$2.01% (n=3) (1st period), 27.88 ${\pm}$ 17.54% (n=4) (2nd period), respectively. The effective permeabilities (Peffs${\times}$10$\^$4/) of ranitidine were 1.51${\pm}$0.47cm/sec (n=3) (1st period), 1.50 ${\pm}$ 0.31 cm/sec (n=4) (2nd period), respectively. The pH and osmolarity of perfusion solution were 7.50 ${\pm}$ 0.03 and 300 ${\pm}$ 0.06 mOsm/L, There was no significant intrasubject variation. Mixing equilibrium (steady-state) was reached at about 50 min. l-Phenylalanine was absorbed almost completely. Intrinsic intestinal wall permeability of ranitidine showed low permeable characteristics, suggesting permeability-limited absorption. The absorption of 1-phenylalanine, an actively transported nutrient, was not inhibited by ranitidine. The low intestinal membrane permeability is one of the important factors responsible for the variable oral absorption of ranitidine. Supported by FDA Grant FD01462-04 and KOSEF Grant.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.133-139
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• 2005

Resonant-Type Magnetometer(RM) using high permeability isotropic magnetic material is designed to implement Smart Digital Compass. Theoretically, the inductance L of a coil, winding on the magnetic core, is proportion to the change of permeability $\mu(H)$ and, the change values of L can be obtain as the change of frequency by simple Schmitt Trigger circuit. By the use of integrated circuit switch, the RM can be designed with simple circuit and it can provide overcoming the drift by temperature and the variation of operating points in $\mu(H)$ curve. The facts that Metglas 2705M is an optimum magnetic material and ship's permanent magnetism can be obtain from measured values of RM are also known in this study.