• 제목/요약/키워드: pure state

검색결과 553건 처리시간 0.022초

Effect of Particle Size and Dispersion on Dielectric Properties in ZnO/Epoxy Resin Composites

  • Yang, Wenhu;Yi, Ran;Yang, Xu;Xu, Man;Hui, Sisi;Cao, Xiaolong
    • Transactions on Electrical and Electronic Materials
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    • 제13권3호
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    • pp.116-120
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    • 2012
  • In this paper, ZnO-Epoxy nanocomposites (NEP) were prepared and epoxy composites that contain 5 wt% micro ZnO (MEP) and deliberately not well dispersed nano ZnO (NDNEP) were also prepared for purpose of comparison. The effects of the particle size and dispersion of ZnO on dielectric properties of epoxy resin were chiefly studied. Test results showed that: at a loading of 5 wt%, the three epoxy composites seem to have no significant difference on resistivity compared to epoxy resin; Dielectric constants of all the epoxy composites are also basically the same but they are bigger compared to that of the pure epoxy resin (unfilled); Dielectric dissipation factors ($tan{\delta}$) of NDNEP is greater than that of NEP and MEP. NEP has the minimum dielectric loss factor, whereas dielectric loss factors of the three epoxy composites are larger than that of the pure epoxy resin. The decreasing order of electrical breakdown strength for the three epoxy composites and for the pure epoxy resin is as follows: NEP>MEP>NDNEP>EP. Finally, in order to explain the experimental results the aggregation interface phase was proposed. Furthermore, addition of well dispersed nano filler has proved to have a positive effect on the improvement of the dielectric properties of epoxy resin.

완전궤환 비선형 계통에 대한 적응 신경망 제어기 (Adaptive Neural Control of Nonlinear Pure-feedback Systems)

  • 박장현;김성환;장영학
    • 전기전자학회논문지
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    • 제14권3호
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    • pp.182-189
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    • 2010
  • 본 논문은 논어파인 완전궤환 비선형시스템에 대한 적응 신경망 제어기를 제안한다. 제안하는 방법은 원래의 계통식을 새롭게 정의되는 상태변수에 대해서 표준 정규식으로 재구성하여 제어식을 구성함으로써 기존의 알고리듬에서 일반적으로 사용하는 백스태핑(backstepping)을 회피할 수 있다는 장점을 갖는다. 백스태핑을 회피함으로서 본 논문에서 제안하는 새로운 방법은 기존의 제어 알고리듬에 비해서 제어기 구조와 안정도 증명이 현저히 간략해 지게 되는 장점을 갖는다. 제안된 제어기는 미지의 이상 제어식을 근사화하기 위해서 오직 하나의 신경망만을 사용하며 이점 역시 기존의 제어알고리듬이 다수의 신경망을 사용하는 것과 구별되는 점이다. 모의실험을 통하여 제안된 알고리듬의 성능과 효율을 보인다.

Transport Properties of Ar-Kr Mixtures: A Molecular Dynamics Simulation Study

  • Min, Sun-Hong;Son, Chang-Mo;Lee, Song-Hi
    • Bulletin of the Korean Chemical Society
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    • 제28권10호
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    • pp.1689-1696
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    • 2007
  • Equilibrium molecular dynamics (EMD) simulations are used to evaluate the transport coefficients of argonkrypton mixtures at two liquid states (state A: 94.4 K and 1 atm; state B: 135 K and 39.5 atm) via modified Green-Kubo formulas. The composition dependency of the volume at state A obeys close to the linear model for ideal liquid mixture, while that at state B differs from the linear model probably due to the high pressure. The radial distribution functions for the Ar-Kr mixture (x = 2/3) show a mixing effect: the first peak of g11 is higher than that of g(r) for pure Ar and the first peak of g22 is lower than that of g(r) for pure Kr. An exponential model of engineering correlation for diffusion coefficient (D) and shear viscosity (η) is superior to the simple linear model for ideal liquid mixtures. All three components of thermal conductivity (λpm, λtm, and λti) at state A and hence the total thermal conductivity decrease with the increase of x. At state B, the change in λtm is dominant over those in λpm and λti, and hence the total thermal conductivity decrease with the increase of x.

Periodic Properties of a Lyapunov Functional of State Delay Systems

  • Young Soo Suh
    • KIEE International Transaction on Systems and Control
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    • 제2D권2호
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    • pp.92-96
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    • 2002
  • This paper is concerned with properties of a Lyapunov functional of state delay systems. It is shown that if a state delay system has a pure imaginary pole for some state delay, then no Lyapunov functional satisfying a Lyapunov condition exists periodically with respect to change of the state delay. This periodic property is unique in state delay systems and has been well known in the frequency domain stability conditions. However, in the time domain stability conditions using a Lyapunov functional, the periodic property is not known explicitly.

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전력용 강재의 정적.동적 크리프의 상관성과 예측 및 AE평가(1); 정적 크리프와 AE평가 (Life Prediction and AE Evaluation of Pure or Cyclic Creep for Power Plant Materials ; Pure Creep and AE Evaluation)

  • 오세규;장홍근;송정근
    • 한국해양공학회지
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    • 제12권1호
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    • pp.76-84
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    • 1998
  • In this 1st report, the relationship between pure creep properties and initial strain was studied and also its acoustic emission test was performed during creep test at 500, 600 and $700^{\circ}C$. And the applicability of the acoustic emission technique was investigated to analyze the quantitive relationship between all the pure properties (creep strength, creep repture time or creep life, steady state creep rate, total creep rate, creep strain, total creep strain, etc.) and the initial strains as well as to analyze AE properties during the pure creep loading condition.

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인력 포텐셜을 갖는 강체구형 기체에 대한 2-매개변수 상태방정식 (A New Two-Parameter Equation of State for Pure Gases of Hard Spheres with An Attractive Potential)

  • 정해영
    • 대한화학회지
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    • 제56권2호
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    • pp.207-211
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    • 2012
  • 강체구형입자에 대한 Carnahan-Starling식과 인력 포텐셜을 갖는 격자 모델을 이용하여 새로운 2-매개변수 상태식을 유도하였다. 이 식을 이용하여 압축인자를 계산하고 Nelson-Obert 압축인자도표와 비교하여 보았다. 그 결과 이 식은 Redlich-Kwong식과 평균적으로 비슷한 정도로 실험적인 압축인자도표와 일치한다는 것을 알 수 있다. 그런데 새 상태식에서 나타나는 매개변수와 항들은 Redlich-Kwong equation의 경우보다 분명한 물리적 의미를 갖고 있다.

EXTREME POINTS RELATED TO MATRIX ALGEBRAS

  • Lee, Tae Keug
    • Korean Journal of Mathematics
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    • 제9권1호
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    • pp.45-52
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    • 2001
  • Let A denote the set {$a{\in}M_n{\mid}a{\geq}0$, $tr(a)=1$}, $St(M_n)$ the set of all states on $M_n$, and $PS(M_n)$ the set of all pure states on $M_n$. We show that there are one-to-one correspondences between A and $St(M_n)$, and between the set of all extreme points of A and $PS(M_n)$. We find a necessary and sufficient condition for a state on $M_{n1}{\oplus}{\cdots}{\oplus}M_{nk}$ to be extended to a pure state on $M_{n1}+{\cdots}+_{nk}$.

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Equations of State for Hard-Sphere Chains: Effect of Attractive Contribution

  • Kim Jae-Jun
    • Macromolecular Research
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    • 제14권2호
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    • pp.220-229
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    • 2006
  • Several equations of state for hard-sphere chains with various perturbation terms are reviewed. For each model, three characteristic parameters are required to represent phase equilibria of normal fluids and obtained from thermodynamic properties of pure saturated liquids. The models are then compared with computer simulation data to show the effect of attractive contribution forms employed. Calculated values of vapor-liquid equilibria (VLE) of hydrocarbons that can be reproduced for each model are also compared with experimental results. An additional parameter, ${\zeta}_{KB}$, is required to represent the VLE of pure water, which is ascertained to have a strong influence on the theoretical coexistence curve.

고무재료의 이축 인장시험에 관한 연구 (A Study on the Equi-biaxial Tension Test of Rubber Material)

  • 김동진;김완두;김완수;이영신
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.425-430
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    • 2003
  • The material properties of rubber was determined by the experiments of uniaxial tension, uniaxial compression, planer tension, equi-biaxial tension and volumetric compression. In compression test, it is difficult to obtain the pure state of compression stress and strain due to friction force between the specimen and compression platen. In this study, the stress and strain data from the equi-biaxial tension test were converted to compression stress and strain and compared to a perfect state of simple compression data when friction was zero. The compression test device with the tapered platen was proposed to overcome the effect of friction. It was turned out that the relationship of the stress and strain using the tapered platen was in close agreement with the pure compressive state.

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A Galerkin Layerwise Formulation for three-dimensional stress analysis in long sandwich plates

  • Ahmadi, Isa
    • Steel and Composite Structures
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    • 제24권5호
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    • pp.523-536
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    • 2017
  • A layerwise (LW) formulation based on the Galerkin method is presented to investigate the three-dimensional stress state in long sandwich plate which is subjected to tension force and pure bending moment. Based on the Galerkin method and the LW discretization approach, the equilibrium equations of elasticity for the long plate are written in the weak form and discretized through the thickness of the plate. The discretized equations are written in terms of displacement components of the numerical layers. The governing equations of the plate are solved analytically for the free edge boundary conditions. The distribution of stress state especially the 3D stress state in the vicinity of the edges of the sandwich plate which is subjected to tension and pure bending is studied. In order to increase the accuracy, the out of plane stresses are obtained by integrating the equilibrium equations of elasticity. The convergence and accuracy of the predictions are studied and various numerical results are presented for distribution of the in-plane and out of plane stresses in symmetric and un-symmetric sandwich plates.