• Title/Summary/Keyword: permeability model

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Filter Clogging of Leachate Collection and Removal System at Waste Landfill (폐기물 매립지 침출수 집.배수 시스템에서 필터 막힘에 관한 연구)

  • 고재학;이재영;노희정
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 1999.10a
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    • pp.77-80
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    • 1999
  • In this study, to evaluate the performance of leachate collection and removal system, the clogging of geotextile filter was tested and simulated for HELP. As a result of clogging test, the all permeability of geotextiles were decreased rapidly in several day. Also, $Ca^{2+}$ and CODcr concentrations were decreased during test. In model simulation for HELP, Daily discharge volume was shown insignificant change with the filter clogging. however, this result may effect on increasing of the hydraulic gradient in waste layer.r.

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Properties and Structure of High Frequency Soft Magnetic Nano-composite Films

  • Ohnuma, Shigehiro;Masumoto, Hiroshi
    • Journal of Magnetics
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    • v.16 no.4
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    • pp.403-407
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    • 2011
  • Metal-insulator type, nano-granular soft magnetic films have been reviewed from the viewpoint of high frequency magnetic materials. The formation of nano-granular structure is related to the magnitude of heat of formation of intergranule materials. Variation of the ratio of granule phase to intergranule phase in the film is found to produce various characteristics in the magnetic properties of the film. The HRTEM observation reveals that neighboring granules in the film with above 60 at.% Co, contact at considerable points and the films show soft magnetic properties which are explainable in terms of the random anisotropy model for nano-crystalline materials. Addition of Ni group elements in Co-O based films enhances their anisotropy field up to 400 Oe and they exhibit excellent frequency response of permeability. Also, large electromagnetic noise suppression effect is demonstrated as one of their potential applications.

Heat and Mass Transfer in Highly Porous Media (고 다공성 물질에서 열 및 물질전달)

  • 이금배
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.3
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    • pp.685-693
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    • 1990
  • The heat transfer coefficients were calculated numerically to see the effects of radiation around the porous medium put on the flat plate at a distance from the leading edge of flat plate for the two-dimensional laminar flows. To verify the analytical model developed and invoke the heat/mass transfer analogy, an experiment was carried out using naphthalene sublimation technique. From the effects of the wake, Sherwood number is maximum around the region where the porous medium is attached. The theoretical results correspond well with the experimental results at small Darcy number. Permeability of ceramic blocks used for experiment was also measured and the Forchheimer equation is applicable in our measurement range.

Anti-inflammatory Activity of Propolis

  • Park, Eun-Hee;Kim, Sun-Hee;Park, Soo-Sun
    • Archives of Pharmacal Research
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    • v.19 no.5
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    • pp.337-341
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    • 1996
  • Propolid (bee-glue), known as a folk medicine, is a lipo;hilic material found in honeybee hives. In the present study on the anti-inflammatory effect of Korean propolis, it was extracted with ethanol, and used as a test material. The $LD_{50}$ value with the oral administration of ethanolic extract of Korean propolis (EEKP) was higher than 2g/kg in mice. The oral administration of the propolis extract (100mg/kg) significantly inhibited the development of hind paw edema induced by carrageenin in rats. the oral pretreatment of the propolis extract markedly inhibited the increase in vascular permeability and the number of writhing induced by acetic acetic acid in mice. Propolis extract, 50 and 100 mg/kg p.o. per day for 7 days, produced a significant inhibitory effect on granuloma and exudate formation in rats. This inhibitory effect was enhanced with the concomitant use of prednisolone (2.5 mg/kg). These results suggest that Korean propolis apparently has a strong anti-inflammatory activity.

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Numerical analysis of high-strength concrete exposed elevated temperature (고온에 노출된 고강도 콘크리트 기둥의 수치해석)

  • Seo, Yeon-Joo;Hong, Sung-Gul
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.21-24
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    • 2005
  • A computational analysis of hygro-thermal and mechanical behaviour of concrete column at high temperature is presented. The objective of this study is to develop a finite difference model that simulates coupled heat and transport phenomena in reinforced concrete structures exposed to rapid heating conditions such as fires. The theoretical basis for the integrated finite difference method is presented to describe a powerful numerical technique for solving of fluid flow in porous media. The numerical results predict the phenomena of 'moisture clog' and the explosive spalling of concrete under fire. The investigations show that high-strength concrete(HSC) and normal-strength concrete(NSC) exposed to high temperature have different pore pressure buildup dependent on porosity, permeability and moisture contents. HSC has more possibility than NSC on spalling.

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Study to Improve Torque of Electromagnetic Clutch by Using FEM (유한요소법을 이용한 전자석클러치의 토크향상에 대한 연구)

  • 박창호;조종두;이상우
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.10a
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    • pp.395-402
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    • 2003
  • In this paper, we try to analyze the torque of electromagnetic clutch by using FEM. For Analysis of the magnetostatic field, we constitute axi-symmetric FEM model of an electromagnetic clutch. By resorting to the theory of magnetic circuits, we obtain a solution of theoretical torque to compare with the result of numerical analysis. From the result of numerical analysis, the air gap of electromagnetic clutch between armature and rotor is important to influence on the torque and the torque changes with the air gap of 0.2mm∼0.1mm Also we observe the characteristic of the torque by changing the relative permeability of each parts. Finally an optimized design of the electromagnetic clutch is proposed.

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Novel Planar Metamaterial with a Negative Refractive Index

  • Kim, Dong-Ho;Choi, Jae-Ick
    • ETRI Journal
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    • v.31 no.2
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    • pp.225-227
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    • 2009
  • A new planar metamaterial (MTM) with simultaneous negative values of permittivity (${\varepsilon}$) and permeability (${\mu}$) is proposed. Our MTM is composed of two identical copper patterns etched on both sides of dielectric laminate, which is very thin and easy to fabricate. Unlike conventional MTMs, the proposed structure shows a negative refractive index (NRI) behavior with respect to a normally incident wave. To explain the underlying principle of the NRI characteristics, an equivalent resonant circuit model based on surface current density distribution is investigated. An eigenmode analysis and a three-dimensional wave simulation for the stacked MTM prism are also performed to verify the existence of negative refraction. The experimental results from the transmission and reflection measurement ensure the validity of our design approach and show good agreement with the theoretically predicted effective medium parameters.

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Electromagnetic Wave Propagation in Anisotropic Composite Structures (이방성 복합재료의 전자기파 투과특성)

  • 전흥재;신현수
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.407-414
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    • 2002
  • The knowledge of interaction of electromagnetic waves in composite structures is important for designing the shielding structure for antenna such as radome. Recently, radomes are constructed in the form of foam core sandwich structures that have many mechanical advantages such as high strength, long fatigue life, low density and adaptability to the intended function of structure. However, the propagation of electromagnetic waves is affected by high anisotropic permeability and loss tangent of the composite skin. In this study, the analytical model to understand the propagation of electromagnetic waves in the anisotropic composites and foam core sandwich structures with composite skins was proposed. Numerical analyses of unidirectional composites and foam core sandwich structure as a function of incident angle were performed. From the results of analysis, the general tendencies of transmittance of electromagnetic wave through composites and foam core sandwich structure were obtained.

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Transdermal Permeation of Riboflavin in Ointment Bases Using Gums & Enhancers (Gum류의 연고제제와 흡수촉진제가 Riboflavin의 경피흡수에 미치는 영향)

  • 오세영;황성규;김판기
    • Journal of Environmental Health Sciences
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    • v.26 no.2
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    • pp.91-96
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    • 2000
  • We investigated characters of transdermal therapeutic system(TTS) and the skin permeability of that with applying drug delivery system(DDS). Natural gums were selected as material of TTS. The permeation of natural gums ointment containing drug in rat skin using diffusion cell model. Permeation properties of materials were investigated for water soluble drug such as riboflavin in vitro. We used glycerin, PEG 600 and oleic acid as enhancers. Since dermis has more hydration than the stratum corneum, skin permeation rate at steady state was highly influenced when glycerin was used in riboflavin. The permeation rate of content enhancer and drug was found to be faster than that of content riboflavin only. These results showed that skin permeation rate of drug across the composite was mainly dependent on the property of ointment base and drug. All the gum ointment tested showed good safety. Proper selection of the materials which resemble and enhance properties of the delivering drug was found to be important in controlling the skin permeation rate.

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Variation of Seepage Line through Embankments by Permeability of Layer (지반의 투수성에 따른 제체 침투류의 변화)

  • 신진환;이봉직
    • Journal of the Korean Society of Safety
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    • v.11 no.2
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    • pp.109-115
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    • 1996
  • The movement of water through a river embankment and its influenced upon the stability of the slope of the embankment are described. The stability of the embankment is depended upon the location of seepage line. As the seepage flow occurs in the embankment, the slope of the embankment loses its stability. Of particular interest is the stability following a rapid change of water level. The variation of seepage line in the embankment model by a fluctuation of water level is discussed. The experimental models were construction with slopes of 1 : 1.5, 1 : 2.0, 1 : 2.5 and the flow velocity was turned from 60cm/sec~90cm/sec. Based on the experimental study, the following conclusions are drawn. 1) When water level is raised, the seepage line of downstream slope Is raised rapidly as flow velocity increases. 2) For the case of permeable layer, the seepage line raised rapidly as compare with impermeable layer when water lever is raised.

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