• Title/Summary/Keyword: variable viscosity

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Studies of Lithium Diffusivity of Silicon-Based Film Electrodes for Rechargeable Lithium Batteries

  • Nguyen, Cao Cuong;Song, Seung-Wan
    • Journal of Electrochemical Science and Technology
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    • v.4 no.3
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    • pp.108-112
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    • 2013
  • Lithium diffusivity of the silicon (Si)-based materials of Si-Cu and $SiO_x$ (x = 0.4, 0.85) with improved interfacial stability to electrolyte have been determined, using variable rate cyclic voltammetry with film model electrodes. Lithium diffusivity is found to depend on the intrinsic properties of anode material and electrolyte; the fraction of oxygen for $SiO_x$ (x = 0.4, 0.85), which is directly related to electrical conductivity, and the electrolyte type with different ionic conductivity and viscosity, carbonate-based liquid electrolyte or ionic liquid-based electrolyte, affect the lithium diffusivity.

THERMAL INSTABILITY IN REACTIVE VISCOUS PLANE POISEUILLE / COUETTE FLOWS FOR TWO EXTREME THERMAL BOUNDARY CONDITIONS

  • Ajadi, Suraju Olusegun
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.13 no.2
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    • pp.73-86
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    • 2009
  • The problem of thermal stability of an exothermic reactive viscous fluid between two parallel walls in the plane Poiseuille and Couette flow configurations is investigated for different thermal boundary conditions. Neglecting reactant consumption, the closed-form solutions obtained from the momentum equation was inserted into the energy equation due to dissipative effect of viscosity. The resulting energy equation was analyzed for criticality using the variational method technique. The problem is characterized by two parameters: the Nusselt number(N) and the dynamic parameter($\Lambda$). We observed that the thermal and dynamical boundary conditions of the wall have led to a significant departure from known results. The influence of the variable pre-exponential factor, due to the numerical exponent m, also give further insight into the behavior of the system and the results expressed graphically and in tabular forms.

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A Case Study of a Six Sigma Project for Improving Gate Painting Quality (게이트 도장 품질 개선을 위한 6시그마 프로젝트 사례 연구)

  • Hong, Sung-Hoon;Choi, Ik-Jun
    • Journal of Korean Society for Quality Management
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    • v.34 no.1
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    • pp.1-12
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    • 2006
  • This paper presents a six sigma project for improving gate painting quality in a medium-sized automotive part company. The project follows a disciplined process of five macro phases: Define, Measure, Analyze, Improve, and Control. A CTQ(critical to quality) is determined based on COPQ(cost of poor quality) analysis, and a process map is utilized for identifying process input variables. Three KPIV s(key process input variable) are selected; Painting Temperature, Painting Quantity, and Painting Viscosity, and DOE(design of experiments) is utilized for finding the optimal process conditions for three KPIVs. MINITAB software is used for data analyses and DOE. The sigma level of defects rate has improved from 2.93 to 3.66.

Quasi-Steady Damping Force of Electro- and magneto-Rheo logical Flow Mode Dampers using Herschel-Bulkley Model (Herschel-Bulkley 모델에 의한 전기 및 자기장 유체 댐퍼의 준안정 상태 댐핑력 해석)

  • Lee, Dug-Young;Hwang, Woo-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1298-1302
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    • 2000
  • Electrorheological(HER) and magnetorheologica(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. ER and MR fluid-based dampers are typically analyzed using Bingham-plastic shear flow analysis under Quasi-steady fully developed flow conditions. An alternative perspective, supported by measurements reported in the literature, is to allow for post-yield shear thinning and shear thickening. To model these, the constant post-yield plastic viscosity in Bingham model can be replaced with a power-law model dependent on shear strain rate that is known as the Herschel-Bulkley fluid model. The objective of this paper is to predict the damping forces analytically in a typical ER bypass damper for variable electric field, or yield stress using Herschel-Bulkley analysis.

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Performance of Squeeze Film Damper Using Magneto-Rheological Fluid (MR유체를 이용한 스퀴즈필름 댐퍼의 응답특성)

  • 안영공;양보석;신동춘;김동조
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.67-70
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    • 2002
  • This paper presents the property of the Squeeze Film Damper (SFD) using Magneto-Rheological fluid (MR fluid). The damping property of a SFD for a flexible rotor system varied according to vibration mode. MR fluid is known as a functional fluid with controllable apparent viscosity of the fluid by applied magnetic field strength. When the MR fluid is applied in the SFD, the SFD using MR fluid can effectively reduce vibrations of the flexible rotor in a wide range of rotating speed by control of the applied magnetic field strength. To investigate in detail the SFD using MR fluid, the SFD to support one mass was constructed and its performance was experimentally investigated in the present study. The damping property of the SFD using MR fluid has viscous damping by Newtonian fluid, but not Coulomb friction by Bingham fluid. Therefore, The system damped by the SFD can be considered as a linear system.

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Analysis of the Effect of Screen Printing Variables on Thick Film Thickness (스크린인쇄조건에 따른 후막인쇄물의 잉크층 두께에 관한 분석)

  • Lim, Kyu-Jin;Yi, Arm;Shin, Jong-Soon
    • Journal of the Korean Graphic Arts Communication Society
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    • v.20 no.2
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    • pp.19-30
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    • 2002
  • Four screen mesh counts of 100, 150, 200, and 305 threads per inch are chosen and a designed test figure is exposed on them for printing experiment to measure the ink deposit thickness. Among a number of variables, the ink viscosity, the screen gap and the squeegee pressure and speed are estimated with their effected thickness. These variables affect as much as around 50% compared with the theoretical ink volume listed by the mesh manufacturer and each variable has different influence on the thickness. The data and graphs have been analyzed for the thick film production.

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Circulation Experiment of the Chinhae Bay using a Three-Dimensional Diagnostic Numercal Model (3차원 진단모델을 이용한 진해만의 수치유동실험)

  • 배삼완
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.33 no.4
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    • pp.360-369
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    • 1997
  • We calculated the residual current forced by buoyancy, wind stress, and tidal stress in the Chinhae Bay using a three-dimensional diagnostic model. The calculated current was also compared with the observation. The flow directs outward from the central area of the Bay in the upper layer, and also forms eddy-shape stucture in the upper and middle layers. The flow of bottom layer shows an opposite pattern compared to those of top and middle layers. The maximum speed was 6.05 em/see (September) and 3.49 cm/sec (November) in the upper layer, and 4.39 cm/sec on both month in the middle layer. The Kinetic energy of November (8.39xlO' W) was larger than that of September (1.24xlO 'W), mainly resulting from larger buoyancy effect in September. In spite of the roughness of the grid size(1 km) and wind date, the calculated flow shows eorrelation(r=0.71) with the observation. We expect that the correlation be increased by increased by adopting the fine grid and the variable coefficients of diffusion and viscosity.

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Numerical simulation of transient laminar compressible convection in a rectangular enclosure (사각형(四角形) 밀폐공간내(密閉空間內)의 과도(過度) 층류(層流) 압축성(壓縮性) 자연(自然) 대류(對流)에 관(關)한 수치해석적(數値解析的) 연구(硏究))

  • Kim, Byung-Yong
    • Solar Energy
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    • v.2 no.1
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    • pp.9-16
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    • 1982
  • The problem of transient laminar natural convection in compressible fluid in a rectangular enclosure is considered. The upper and lower boundaries of the enclosure are thermally insulating and the side boundaries are maintained at fixed temperatures. The fluid is considered to be a perfect gas with constant viscosity and thermal conductivity and the formulation differs from the boussinesq simplification in that the effects of variable density are completely retained. The motions are restricted to two dimensions. For incompressible fluid, the natural convection is driven mainly by buoyancy force. But the solutions show that for compressible fluid, the natural convection is driven by pressure and buoyancy forces and the thermally induced motion is acoustic in nature.

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The Lubrication Characteristics of the Vane Tip Under Pressure Boundary Condition of Oil Hydraulic Vane Pump

  • Cho Ihn-Sung;Oh Seok-Hyung;Song Kyu-Keun;Jung Jae-Youn
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1716-1721
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    • 2006
  • The Lubrication Mode of line contacts between the vane and the camring in an oil hydraulic vane pump has been investigated. First, the variations of the radial force of a vane were calculated from previous measurements of dynamic internal pressure in four chambers surrounding a vane. Next, the lubrication modes were distinguished with Hooke's chart, which is an improvement over Johnson's chart. Finally, the influence of the boundary conditions in the lubrication region on the fluid film lubrication was examined by calculating the film pressure distributions. The results showed that the lubrication mode of the vane tip exists in the rigid-variable-viscosity region, and that discharge pressure higher than 7 MPa greatly affects the oil film pressure in the small and the large arc section because of the Piezo-viscous effect.

무한 소폭 전기유변 스퀴즈 필름 댐퍼의 해석

  • 정시영
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1994.06b
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    • pp.19-29
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    • 1994
  • Since Winslow (1) has reported an electro - theological (ER) effect which features remarkable and reversible changes in the properties of the fluid due to an imposed external electric field, numerous applications of ER fluids in mechanical devices, such as clutches, control valves, active dampers, and etc. have been proposed to improye dramatical ly their performances (2,3). When the external electric field is imposed to the ER fluid, it behaves as a Bingham fluid, displaying a field dependent yield shear stress which is widely variable. Without the electric field, the ER fluid has a reversible and constant viscosity so that it flows as a Newtonian fluid. Another salient feature of the ER fluid is that the time required for the variation is very short (< 0.001 sec) (4-6). These attractive.characteristics of the ER fluid provide the possibility of the appearance of new engineering technology , for instance, an active vibration control system. Recently, the application of the ER fluid to rotor-bearing systems has been also initiated.

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