• 제목/요약/키워드: approximation model

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AN EXTENSION OF SOFT ROUGH FUZZY SETS

  • Beg, Ismat;Rashid, Tabasam
    • Korean Journal of Mathematics
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    • 제25권1호
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    • pp.71-85
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    • 2017
  • This paper introduces a novel extension of soft rough fuzzy set so-called modified soft rough fuzzy set model in which new lower and upper approximation operators are presented together their related properties that are also investigated. Eventually it is shown that these new models of approximations are finer than previous ones developed by using soft rough fuzzy sets.

Higber Order Expansions of the Cumulants and the Modified Normalizing Process of Multi-dimensional Maximum Likelihood Estimator

  • Jonghwa Na
    • Communications for Statistical Applications and Methods
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    • 제6권1호
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    • pp.305-318
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    • 1999
  • In this paper we derive the higher order expansions of the first four cumulants of multi-dimensional Maximum Likelihood Estimator (MLE) under the general parametric model up to and including terms of order O({{{{ {n }^{-1 } }}}}) Also we obtain the explicit form of the expansion of the normalizing trans formation of multi-dimensional MLE and show that the suggested normalizing process is much better than the normal approximation based on central limit theorem through example.

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층 구조를 갖는 초전도체내의 자기 다발선계에서의 열적 요동의 효과 (Effects of Thermal Fluctuations on Vortices in a Layered Superconductor)

  • 여준현
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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    • pp.22-25
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    • 1999
  • We apply the nonperturbative parquet approximation method, which was previously used to study the effect of thermal fluctuations in two-dimensional vortex systems, to vortices in a layered superconductor. We set up the parquet equations for the Lawrence-Doniach model and present two different numerical methods to solve them. The results for a superconductor consisting of two and four layers are also discussed in connection with an observed first order transition line in the vortex liquid regime.

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비선형 상태 변수 관측기의 효과적인 이득 선정에 관한 연구 (A study on an effective tuning of a nonlinear state observer)

  • 이훈구;탁민제
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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    • pp.636-641
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    • 1993
  • Recent researches on control theory enable nonlinear state feedback which is more closer to real system without approximation. To apply nonlinear control theories, all state variables should be measured or estimated. In this paper, a technique of designing nonlinear state observer for a particular class of nonlinear system is presented. The result is applied to an aircraft model to prove the convergency of observation error.

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Significance of rigorous fluid-foundation interaction in dynamic analysis of concrete gravity dams

  • Lotfi, Vahid
    • Structural Engineering and Mechanics
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    • 제21권2호
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    • pp.137-150
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    • 2005
  • Dynamic analysis of dam-reservoir-foundation system is usually carried out by employing a simplified and approximate one-dimensional model to account for fluid-foundation interaction. The approximation introduced on this basis is examined thoroughly in this paper by comparing the method with the rigorous approach. It is concluded that the errors due to approximate method could be very significant both for horizontal and vertical ground motions.

Analysis of transport properties of SLS polysilicon TFTs

  • Fortunato, G.;Bonfiglietti, A.;Valletta, A.;Mariucci, L.;Rapisarda, M.;Brotherton, S.D.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.513-518
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    • 2006
  • An investigation of the transport properties of polysilicon TFTs, using sequential laterally solidified, SLS, material, is presented. This material has a location controlled distribution of grain boundaries, GBs, which makes it particularly useful for the analysis of their influence on the performance of polysilicon TFTs, and to address the issue of the role of spatially localised trapping states. The experimental results were analyzed by using numerical simulations, and the effective medium approximation was compared with a discrete grain model.

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최적 전력 조류 해법에 관한 연구 (A Study on the Optimal Power Flow Solution)

  • 유석구;민평오
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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    • pp.176-179
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    • 1989
  • Newton's OPF algorithm, for each iteration, solves with second order approximation of Lagraqngian function and sparse matrix technique. When load model is applied to this technique, load voltages have tendency to be fixed at lower limit. It makes the solution inadequte. In this paper, reference bus voltage specification technique suggested to make adequate load voltage. This method is verified useful 6-bus Ward-Hale sample system.

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Simulink을 이용한 10bit 20MSPS Successive Approximation Register ADC의 모델링 (Modeling of 10bit 20MSPS SAR ADC using Simulink)

  • 박재정;문병권;김대정
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2008년도 하계종합학술대회
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    • pp.461-462
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    • 2008
  • An elaborate Simulink model for a nonredundant 10bit 20MSPS SAR ADC is proposed to verify its algorithm and to consider the real transistor-level issues of analog blocks. Some electrical trade-offs and power issues are considered.

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비선형 유압 서보시스템의 비선형 변환 및 이에 대한 선형제어에 관한 연구 (Application of the nonlinear transformation and linear state state feedback control to nonlinear hydraulic servo system)

  • 김영준;장효환
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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    • pp.272-275
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    • 1989
  • In this paper feedback linearization of valve-controlled nonlinear hydraulic velocity control system is studied. The $C^{\infty}$ nonlinear transformation T is obtained, and it is shown that this transformation is global one. Linear equivalence of nonlinear hydraulic velocity control system is obtained by this global nonlinear transformation, and linear state feedback control law is applied to this linear model. It is shown that this transformation method is to the linear approximation by simulation study..

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A Preconditioning Method for Two-Phase Flows with Cavitation

  • Shin B.R.;Yamamoto S.
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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    • pp.181-182
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    • 2003
  • A preconditioned numerical method for gas-liquid to-phase flow is applied to solve cavitating flow. The present method employs a density based finite-difference method of dual time-stepping integration procedure and Roe's flux difference splitting approximation with MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The method permits simple treatment of the whole gas-liquid two-phase flow field including wave propagation, large density changes and incompressible flow characteristics at low Mach number. By this method, two-dimensional internal flows through a venturi tuve and decelerating cascades are computed and discussed.

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