• Title/Summary/Keyword: Aspect Ratio Distribution

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A Study on Prediction of Young's Modulus of Composite with Aspect Ratio Distribution of Short Fiber (장단비 분포를 갖는 단섬유 복합재의 영계수 예측에 대한 연구)

  • Lee, J.K.
    • Journal of Power System Engineering
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    • v.10 no.4
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    • pp.99-104
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    • 2006
  • Young's modulus of composite has been predicted by Eshelby's equivalent inclusion method modified with Mori-Tanaka's mean field theory, where short fibers of aspect ratio distribution are assumed to be aligned. Young's modulus of the composite is predicted with the smallest class interval for simulating the actual distribution of fiber aspect ratio, which is compared with that computed using different class intervals. Young's modulus of the composite predicted with mean aspect ratio or the largest class interval is overestimated by the maximum 10%. As the class interval of short fibers for predicting Young's modulus decreases, the predicted results show good agreements with those obtained using the actual distribution of fiber aspect ratio. It can be finally concluded from the study that if and only if the class interval of short fiber normalized by the maximum aspect ratio is smaller than 0.1, the predicted results are consistent with those obtained using the actual distribution of aspect ratio.

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EFFECT OF ASPECT RATIO ON SLIP FLOW IN RECTANGULAR MICROCHANNELS

  • Islam, Md.Tajul;Lee, Yeon-Won
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2803-2810
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    • 2007
  • Three dimensional numerical studies were carried out to investigate the effect of aspect ratio on gas slip flow in rectangular microchannels. We focused on aspect ratio effect on slip velocity, pressure distribution and mass flow rate. As aspect ratio decreases the wall slip velocity also decreases. As a result nonlinearity of pressure distribution increases. The slip velocities on sides and top/bottom walls are different and this difference decreases with increasing aspect ratio. These two velocities are equal when aspect ratio is 1. The ratios of slip mass flow rate over noslip mass flow rate increases with increasing aspect ratios.

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Numerical Study on the Distribution Characteristics of Aluminum Plate-Fin Heat Exchangers According to the Distributor Aspect Ratio (알루미늄 플레이트-핀 열교환기의 분배기 형상비에 따른 분배특성에 관한 해석적 연구)

  • Lee, Eung-Chan;Kang, Hoon;Heo, Jae-Hyeok;Kim, Yong-Chan;Park, Jae-Hong;Cho, Sung-Youl
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.8
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    • pp.805-814
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    • 2011
  • Aluminum plate-fin heat exchangers (ALPHEs) are widely used in petroleum and gas-treated processes. The performance of the ALPHE is strongly dependent on the distribution characteristics of the header and the distributors of each fluid. In this paper, we define the aspect ratio in the side-entry type distributor and analyze the distribution characteristics using CFD-based numerical methods. The phenomena of velocity deviation and distribution with the aspect ratio and the inlet Reynolds number were analyzed by applying relative and absolute maldistribution parameters, and an optimum aspect ratio with the inlet Reynolds number was presented.

Theoretical Analysis of Secondary Current Distributions for Electrode with a Projection Part in Electroplating System (돌출부를 지닌 전극의 전기도금시스템에 대한 이론적 이차 전류분포 해석)

  • Sohn, Tai-Won;Ju, Jeh-Beck
    • Journal of the Korean Electrochemical Society
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    • v.12 no.4
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    • pp.317-323
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    • 2009
  • Theoretical calculations for the secondary current distributions for the electrode with a projection part in electroplating were performed. Two kinds of electrodes were considered. One is a electrode with the overall conducting surfaces(Case 1) and the other is an electrode in which only a projection part has a conducting surface(Case 2). The effects of applied potential, the ratio of ion exchange current to conductivity, $\xi$ and the aspect ratio on the current distribution were examined. The increase of applied current or the value of $\xi$ decreased the uniformity of current distribution. The small value of aspect ratio resulted the more uniform current distribution and Case 2 showed the better uniformity than Case 2. When this model was applied into an electrode with various projection parts, the local current distribution along the electrode surface were obtained successfully. In this case, the decrease of $\xi$ also increase the uniformity of current distribution as seen previously.

Vaned Wheel Atomization of CWM (Vaned Wheel Atomizer에 의한 CWM 미립화)

  • 김성준;김용선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.5
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    • pp.974-982
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    • 1992
  • The atomizations of CWM slurry and water are done by a wheel atomizer which is designed and manufactured for this experiment. The variables of the experiment are the angle of vane, aspect ratio, particle loading and the mean size of coal particle distribution. The main purposes of the experiment are to know how the angle of vane and aspect ratio of vane influence the size distribution of CWM droplets. The experimental results say there are no appreciable effects on the mean size of CWM droplets from the change of loading of coal prticles in slurry. The mean size of coal particle in slurry, however, influence quite strongly the mean size of CWM droplets. The mean size of CWM droplets is quite strongly affected by the angle of vane. The size distribution of CWM droplets is controllable by the change of aspect ratio.

Accuracy of Intersection Counting Method in Measurement of Fiber Orientation Angle Distribution Using Image Processing (화상처리에 의한 섬유배향각 분포측정에 있어서 교차점합산법의 정밀도)

  • 이상동;박준식;이동기;한길영;김이곤
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.12
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    • pp.97-105
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    • 1998
  • The fiber oriented condition inside fiber reinforced composite material is a basic factor of mechanical properties of composite materials. It is very important to meausure the fiber orientation angle for the determination of molding conditions, mechanical characteristics, and the design of composite materials. In the work, the fiber orientation distribution of simulation figure plotted by PC is measured using image processing in order to examine the accuracy of intersection counting method. The fiber orientation function measured by intersection counting method using image processing is compared with the calculated fiber orientation function. The results show that the measured value of fiber orientation function using intersection counting method is lower than the calculated value, because the number of intersection between the scanning line and the fiber with smaller fiber aspect ratio is counted less than with larger fiber aspect ratio.

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Effects of Aspect and Area Ratio of Fiber on the Accuracy of Intensity Method in Measurement of Fiber Orientation-Angle Distribution (섬유배향각 분포측정에 있어서 농도법의 정밀도에 미치는 섬유종횡비와 면적비의 영향)

  • Lee, S.D.;Kim, H.;Lee, D.G.;Han, G.Y.;Kim, E.G.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.4
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    • pp.953-959
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    • 1998
  • To investigate accuracy of intensity method for measurement of the fiber orientation distribution, fiber orientation function is calculated by drawing simulation figures for the fiber orientation as varying fiber aspect ratio, fiber area ratio, and fiber orientation state, respectively. The values of fiber orientation function measured by intensity method are compared with the calculated values of fiber orientation function. The results show that measurement accuracy of the fiber orientation angle distribution by intensity method is affected by the fiber aspect ratio when the total length of oriented fiber is same. The average gradient of fiber orientation function is 0.94 for 1000mm of the total fiber length and is 0.93 for 2000 mm when the fiber aspect ratio is over 50. Measurement accuracy by intensity method is about 94% and the reliable data can be obtained by intensity method.

Simulation of heat flow for rectangular electrodes (사각형 전극에서의 열유동 해석)

  • 신윤섭;박수웅;나석주
    • Journal of Welding and Joining
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    • v.8 no.1
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    • pp.62-69
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    • 1990
  • Being focused on the recent studies that the fatigue strength of resistance spot weldmentes can be improved by using ellipsoidal weld nuggets, the voltage and temperature distribution in resistance spot weldments were simulated for the various rectangular electrodes which had the different aspect ratio of the contact area. Because the electrode shape was not axi-symmetric, the solution domain for simulation should be three dimensional. A series of experiments were carred out to verify the analytically obtained temperature distribution in the weldment. From the calculational and experimental results, it could be revealed that the nugget took the form of ellipsoid, while both results showed a considerable discrepancy for the high aspect ratio.

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Directional Effect of Applied Pressure during the Sintering on the Microstructures and Fracture Toughness of Heat-treated Silicon Nitride Ceramics (소결시의 가압방식이 열처리 후 질화규소의 미세조직과 파괴인성에 미치는 영향)

  • 이상훈;박희동;이재도
    • Journal of the Korean Ceramic Society
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    • v.32 no.6
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    • pp.653-658
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    • 1995
  • Directional effect of applied pressure during sintering on the microstructure and fracture toughness of the heat-treated silicon nitride ceramics has been investigated. The specimens with a composition of 92Si3N4-8Y2O3(in wt%) were sintered at 172$0^{\circ}C$ by a hot press (HP ) and a hot isostatic press (HIP) and heat-treated for grain growth at 1800~20$0^{\circ}C$. The fracture toughness of the HP samples increased with the grain size while the fracture toughness of the HIP treated samples remained the same even though the grain growth occurred. This discrepancy was explained by a bimodal grain size distribution and large aspect ratio of the HPed samples and a monomodal grain size distributjion and samll aspect ratio of the HIP treated samples.

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Aspect Ratio Behavior of Grinding Particles with Variation of Particle Size by Wet Grinding (습식분쇄에 의한 입자크기 변화에 따른 분쇄입자의 종횡비 거동)

  • Choi, Jin Sam
    • Korean Journal of Materials Research
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    • v.30 no.5
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    • pp.223-230
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    • 2020
  • As a case study on aspect ratio behavior, Kaolin, zeolite, TiO2, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 mm media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ~6 ㎛ are shifted to submicron size, D50 ~0.6 ㎛ after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.