• Title/Summary/Keyword: Element dispersion

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Experimental and Numerical Study of Heating Characteristics of Discontinuous Carbon Fiber-Epoxy Composites (불연속 탄소섬유-에폭시 복합재의 발열성능 평가)

  • Kim, Myungsoo;Kong, Kyungil;Kim, Nari;Park, Hyung Wook;Park, Ounyoung;Park, Young-Bin;Jung, Mooyoung;Lee, Sang Hwan;Kim, Su Gi
    • Composites Research
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    • v.26 no.1
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    • pp.72-78
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    • 2013
  • This study explores the resistive heating characteristics of discontinuous carbon fiber (CF)-epoxy composites. Test samples including 1, 3, and 5 wt.% CF were fabricated using sonication and cast molding processes. For heating performance characterization, DC currents were applied to the composite samples, and surface temperatures were evaluated visually and quantitatively using an infrared camera. To estimate the thermal performance of composites and verify the experimental results, finite element analyses were performed. The resistive heating mechanism was investigated in connection with CF loading and applied voltages. Resistive heating efficiency increased proportionately with CF concentration and applied voltage. To obtain homogeneous temperature distribution of the samples, high degree of CF dispersion is required.

A Study on the Contaminant Transport Characteristics in Han River (한강 하류부에서의 오염물질의 거동특성 연구)

  • Kim, Hyeong-Il;Lee, Jong-Seol
    • Journal of Korea Water Resources Association
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    • v.31 no.1
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    • pp.85-93
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    • 1998
  • This study is to analyze and predict the contaminant transport based on the hydrauli characteristics using 2-dimensional finite element model. The dynamic wate quality model. RMA-4. is used to predict the contaminant transport using the hydrulic characteristics obtained from RMA-2v model. The study region is from downstream of Cham-sil weir to upstream of Shin-Kok weir. From the results of contaminant transport analysis. it is shown that the variations of discharge and velocity give quite large effect to the transport and dispersion of contaminant material. and that the water qualities of Joong-Rang and Tan streams play an important role to the downstream also. when the incidental contaminant accident occurs and contaminant material moves to the downstream. it is resulted the decreasing of the maximum COD and the increasing of the duration time to be affected by contaminant. Finally. 2-dimensional analysis is required in the case of large river like Han River. since the large difference of contaminant concentration has been investigated in the left and right bank.

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Numerical Analysis for the Characteristic Investigation of Homogenization Techniques Used for Equivalent Material Properties of Functionally Graded Material (기능경사 소재 등가 물성치 예측을 위한 균질화 기법의 특성분석을 위한 수치해석)

  • Cho, Jin-Rae;Choi, Joo-Hyoung;Shin, Dae-Sub
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.1
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    • pp.13-20
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    • 2008
  • Graded layers in which two different constituent particles are mixed are inserted into functionally graded material such that the volume fractions of constituent particles vary continuously and functionally over the entire material domain. The material properties of this dual-phase graded region, which is essential for the numerical analysis of the thermo-mechanical behavior of FGM, have been predicted by traditional homogenization methods. But, these methods are limited to predict the global equivalent material properties of FGMs because the detailed geometry information such as the particel shape and the dispersion structure is not considered. In this context, this study intends to investigate the characteristics of these homogenization methods through the finite element analysis utilizing the discrete micromechanics models of the graded layer, for various volume fractions and external loading conditions.

A radial point interpolation method for 1D contaminant transport modelling through landfill liners

  • Praveen Kumar, R.;Dodagoudar, G.R.
    • Geomechanics and Engineering
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    • v.2 no.2
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    • pp.141-156
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    • 2010
  • In the framework of meshfree methods, a new methodology is developed based on radial point interpolation method (RPIM). This methodology is applied to a one-dimensional contaminant transport modelling in the saturated porous media. The one-dimensional form of advection-dispersion equation involving reactive contaminant is considered in the analysis. The Galerkin weak form of the governing equation is formulated using 1D meshfree shape functions constructed using thin plate spline radial basis functions. MATLAB code is developed to obtain the numerical solution. Numerical examples representing various phenomena, which occur during migration of contaminants, are presented to illustrate the applicability of the proposed method and the results are compared with those obtained from the analytical and finite element solutions. The proposed RPIM has generated results with no oscillations and they are insensitive to Peclet constraints. In order to test the practical applicability and performance of the RPIM, three case studies of contaminant transport through the landfill liners are presented. A good agreement is obtained between the results of the RPIM and the field investigation data.

The effect of embedding a porous core on the free vibration behavior of laminated composite plates

  • Safaei, Babak
    • Steel and Composite Structures
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    • v.35 no.5
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    • pp.659-670
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    • 2020
  • This paper proposes the use of a porous core between layers of laminated composite plates to examine its effect on the natural frequencies of the resulted porous laminated composite sandwich plate (PLCSP) resting on a two-parameter elastic foundation. Moreover, it has been suggested that the dispersion of porosity has two different functionally graded (FG) patterns which are compared with a uniformly dispersed (UD) profile to find their best vibrational efficiency in the proposed PLCSPs. In FG patterns, two types of dispersions, including symmetric (FG-S) and asymmetric (FG-A) patterns have been considered. To derive the governing Eigen value equation of such structures, the first order shear deformation theory (FSDT) of plates has been employed. Accordingly, a finite element method (FEM) is developed to solve the derived Eigen value equation. Using the mentioned theory and method, the effects of porosity parameters, fiber orientation of laminated composite, geometrical dimensions, boundary conditions and elastic foundation on the natural frequencies of the proposed PLCSPs have been studied. It is observed that embedding porosity in core layer leads to a significant improvement in the natural frequencies of PLCSPs. Moreover, the natural frequencies of PLCSPs with FG porous core are higher than those with UD porous core.

Study on the gate cutting of light guiding plate for mobile using quenching element (박형 도광판의 음각, 양각 마이크로 패턴 성형성에 관한 연구)

  • Hwang, Chul-Jin;Kim, Jong-Sun;Min, In-Gi;Kim, Jong-Dug;Yoon, Kyung-Hwan
    • Design & Manufacturing
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    • v.2 no.5
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    • pp.1-4
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    • 2008
  • LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of kernel parts of LCD unit and it consists of several optical sheets(such as prism, diffuser and protector sheets), LCP (Light Guide Plate), light source (CCFL or LED) and mold frame. The LGP of LCD-BLU is usually manufactured by forming numerous dots with $50-200{\mu}m$ in diameter on it by erosion method. But the surface of the erosion dots of LGP is very rough due to the characteristics of the erosion process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. Especially, the negative and positive micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP.

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A Study on the Performance of Pulse Jet Cleaning in High Temperature Filter (고온 세라믹필터의 펄스젯 탈진 성능에 관한 연구)

  • Kim Byong Ryol;Park Seung Chul;Park Byoung Chul;Cho Hynu Joon;Oh Hyoung Mo;Hwang Tae Won;Shin Sang Woon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.3 no.1
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    • pp.9-16
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    • 2005
  • To evaluate parameters influencing on the dust removal of the High Temperature Filter(HTF) system, a computer simulation of fluid dynamics inside the system had been performed. The results showed that the optimum pulse jet periods were 50ms and 90ms for the 1000mm and 1500mm long filter elements respectively. Dust removal effect was very excellent under the pulse jet pressure of 3 bar. But the distance between the pulse jet nozzle and the venturi of a filter element had no meaningful effect on the performance with the variation from 5mm to 10mm. Compared to the dispersion mode of pulse jet, the collective mode of pulse jet flow was preferable in maintaining the pressure inside the system stable.

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FABRICATION AND TEST OF AN OPTICAL GRISM (가시광선용 그리즘의 제작과 성능시험)

  • Lee, D.H.;Song, J.W.;Yoon, T.S.
    • Publications of The Korean Astronomical Society
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    • v.28 no.3
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    • pp.75-82
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    • 2013
  • An optical grism for education is fabricated and tested. It is composed of a transmission grating as dispersion element and a prism as diffraction angle compensation device. The transmission grating is Edmundoptics #49-584(spatial frequency 600 lines/mm, dimension $50mm{\times}50mm$). The prism is the fused silica type with angles ($41.3^{\circ}$, $-48.7^{\circ}$, $-90^{\circ}$). The grism device is fabricated by bonding the transmission grating and the prism with an optical adhesive. The zig for assembling the grism, telescope and camera is composed of an aluminum tube, an aluminum disk ring and a T-ring camera adaptor. The fabricated optical grism spectrograph is tested in laboratory using Halogen lamp and Neon lamp with DSLR camera. And the grism assembled with reflector telescope is tested in a field using stellar light. The results show good agreements with design parameters. The wavelength coverage range of the grism is 250 nm at the un-deviated wavelength of 506 nm. The wavelength resolution is 0.11 nm/pixel.

Flow Characteristics of Fine Particles for Separated Device Shapes (분리장치의 형상에 따른 미립자 유동특성)

  • Hwang, Seon Kyeong;Lee, Seoung Soo;Jung, Hyo Sang
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.5
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    • pp.544-551
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    • 2013
  • Recently high speed mixer, which is mixing, grinding, dispersion for liquid-liquid material, has been widely used several industries such as food, cosmetics, pharmaceuticals, fine chemicals, electronic material. This high speed mixer has a core element part called particle separation device. Particle separation device, which makes mixed liquid and liquid material using shear forces from a rotor and a stator, is a decisive factor in the distributed parts. In this study, we examined the velocity distribution of the two models of particle separation device using computation fluid dynamics, so that we were able to see the difference of the velocity distribution according to the shape. Also, by experiment, we observed that the use of rotor-screen type is deemed more suitable in case of accurately considering the effect of improving of the dispersibility through the circulation of the future.

Wave dispersion characteristics of nonlocal strain gradient double-layered graphene sheets in hygro-thermal environments

  • Ebrahimi, Farzad;Dabbagh, Ali
    • Structural Engineering and Mechanics
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    • v.65 no.6
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    • pp.645-656
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    • 2018
  • Importance of procuring adequate knowledge about the mechanical behavior of double-layered graphene sheets (DLGSs) incensed the authors to investigate wave propagation responses of mentioned element while rested on a visco-Pasternak medium under hygro-thermal loading. A nonlocal strain gradient theory (NSGT) is exploited to present a more reliable size-dependent mechanical analysis by capturing both softening and hardening effects of small scale. Furthermore, in the framework of a classical plate theory the kinematic relations are developed. Incorporating kinematic relations with the definition of Hamilton's principle, the Euler-Lagrange equations of each of the layers are derived separately. Afterwards, combining Euler-Lagrange equations with those of the NSGT the nonlocal governing equations are written in terms of displacement fields. Interaction of the each of the graphene sheets with another one is regarded by the means of vdW model. Then, a widespread analytical solution is employed to solve the derived equations and obtain wave frequency values. Subsequently, influence of each participant variable containing nonlocal parameter, length scale parameter, foundation parameters, temperature gradient and moisture concentration is studied by plotting various figures.