• Title/Summary/Keyword: Fitting function

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An Improved Distributed Equivalent Circuit Modeling for RF Components by Real-Coefficient AFS Technique

  • Kim, Koon-Tae;Ko, Jae-Hyeong;Paek, Hyun;Kahng, Sung-Tek;Kim, Hyeong-Seok
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.408-413
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    • 2011
  • In this paper, a real-coefficient approach to Adaptive Frequency Sampling (AFS) technique is developed for efficient equivalent circuit modeling of RF components. This proposed method is advantageous than the vector fitting technique and the conventional AFS method in terms of fewer samples leading to a lower order of a rational function on a given data and to a direct conversion to an equivalent circuit for PSPICE(Personal Simulation Program with Integrated Circuit Emphsis) simulation, respectively. To validate the proposed method, the distributed equivalent circuit of a presented multi-layered RF low-pass filter is obtained using the proposed real-coefficient AFS, and then comparisons with EM simulation and circuit simulation for the device under consideration are achieved.

A Basic Study on the signal Processing and Analysis of ECG (심전도 신호처리 및 분석에 관한 기초연구)

  • 정구영;권대규;유기호;이성철
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.294-294
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    • 2000
  • In this paper, we would like to discuss the signal processing and the algorithm for ECG analysis. The ECG gives us information about the condition of the heart muscle, because myocardial abnormality or infarction is inscribed on the ECG during myocardial depolarization and repolarization. Analyzing the ECG signal, we can find heart disease, for example, arrhythmia and myocardial infarction, etc. Particularly, detecting arrhythmia is more important, because serious arrhythmia can take away the life from patients within ten minutes. The wavelet transform decomposes the ECG signal into high and low frequency component using wavelet function. Recomposing high frequency bands including QRS complex, we can detect QRS complex and eliminate the noise from the original ECG signal. To recognize the ECG signal pattern, we adopted the curve-fitting partially and statistical method. The ECG signal is divided into small parts based on QRS complex, and then, each part is approximated to the polynomials. Comparing the approximated ECG pattern with some kinds of heart disease ECG pattern, we can detect and classify the kind of heart disease.

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Determination of the Forming Limit Strain of Sheet Metal Using Inverse Quartic Curve Fitting (역4차식 곡선근사에 의한 판재 성형한계변형률의 결정)

  • Lee, J.S.;Kim, J.D.;Kim, H.J.
    • Transactions of Materials Processing
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    • v.22 no.6
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    • pp.328-333
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    • 2013
  • The current study aims to determine the limit strains more accurately and reasonably when producing a forming limit curve (FLC) from experiments. The international standard ISO 12004-2 in its recent version (2008) states that the limit major strain should be determined by using the best-fit inverse second-order parabola through the experimental strain distribution. However, in cases where fracture does not occur at the center of the specimen, due to insufficient lubrication, the inverse parabola does not give a realistic fit because of its intrinsic symmetry in shape. In this study it is demonstrated that an inverse quartic function can give a much better fit than an inverse parabola in almost all FLC test samples showing asymmetric strain distributions. Using a quartic fit creates more reliable FLCs.

A Study on Reverse Design of Cam Mechanism using NURBS (NURBS를 이용한 캠 기구의 역설계에 관한 연구)

  • 김상진;신중호;김대원;윤호업
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.920-924
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    • 2002
  • This paper presents the reverse design of a cam mechanism using NURBS(Nonuniform Rational B-spline curve). Cam is very difficult to make the accurate shape on the design and the manufacture. Because the cam shape is commonly made in order to move in special functions. The reverse design can be used to check accuracy between the designed data and the manufactured data of the cam shape and also reproduce the cam without the design data. The reverse design procedures consist of motion analysis and curve fitting. The motion analysis is used the central difference method and the relative velocity method to find the displacement and velocity. The curve fitting is used NURBS to develope the whole curve. The central difference method is derived in the 3 dimensional space.

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PWF-GPH method for the statistical analysis of failure time data (고장시간 자료의 통계적 분석을 위한 PWF-GPH 방법)

  • 김선영;윤복식
    • Journal of the military operations research society of Korea
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    • v.22 no.1
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    • pp.114-128
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    • 1996
  • In this paper, a life distribution fitting method based on generalized phase-type distributions(GPH) is presented. By fitting the life distribution to a GPH, we can utilize various useful properties of the GPH. Two different approaches are used according to the properties of the given failure time data. One is an approximation to a GPH through the piecewise Weibull failure rate(PWF) model and the other is a direct approximation to a GPH using the empirical distribution function. Two numerical examples are also presented. In the first example, both of the two approaches are utilized and compared for an incomplete data set. And in the second example, the direct approximation method from an empirical distribution is utilized for the analysis of a complete data set. In both cases, we could confirm the validity of the proposed method.

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Z-Domain Frequency Dependent AC System Equivalent for Electromagnetic Transient Studies (전자기 과도 현상 해석을 위한 Z 영역에서의 주파수 의존 교류시스템 등가)

  • Wang, Yong-P.;Hur, Dong-Y.;Park, Hee-C.;Chung, Hyeng-H.
    • Proceedings of the KIEE Conference
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    • 2001.11b
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    • pp.252-255
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    • 2001
  • Modern power systems are very complex and to model them completly is impractical for electromgnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). In this paper a method for developing FDNE is presented and demonstrated. The FDNE is generated by Linearized Least Square fitting the frequency response of a z-domain formulation. The advantage of this approach is that a direct implementation occurs which dose not incur errors due to discretization inherent with implementing a fitting function in the s-domain. The developed FDNE is accurate and efficient.

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S-Domain Equivalent System for Electromagnetic Transient Studies PART II : Frequency Dependent AC System Equivalent (전자기 과도현상 해석을 위한 S 영역 등가시스템 PART II: 주파수 의존 교류 시스템 등가)

  • Chung Hyeng-Hwan;Wang Yong-Peel
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.4
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    • pp.165-171
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    • 2005
  • Electromagnetic transient simulation can be used to model complex non-linearities that very difficult to represent adequately in the frequency domain. This problem is greatly reduced with the use of frequency dependent network equivalents for the linear part of the system. S-domain rational function fitting techniques for representing frequency dependent equivalents have been developed using Least Squares Fitting(LSF). However it does not suffer the implementation error that exited in this work as it ignored the instantaneous term. This paper presents the formulation for developing 2 port Frequency Dependent AC System Equivalent(FDACSE) with the instantaneous term in S-domain and illustrates its use. This 2 port FDNE have been applied to the New Zealand AC system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the 2 port (FDACSE) developed with Norton Equivalent network. The study results have indicated the robustness and accuracy of 2 port FDACSE for electromagnetic transient studies.

A Study on Service Strategy of Best Transportation Business;Based on Airlines (초우량운송기업의 서비스전략에 관한 연구;항공운송기업을 중심으로)

  • Yang, Han-Mo
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.6 no.1
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    • pp.71-98
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    • 1998
  • The study proved the fitness between competitive strategy and service operation strategy of service companies. The competitive strategy of a corporation is a major strategy playing the role of bridge linking both corporate strategy and functional strategy. And it is a choice of method how to win competitors in given area. There have been such a specific methodologies for acquiring competitive advantage as Porters competitive strategy, Miles and Snows adaptive strategy, and Life cycle strategy. But, many scholars have pointed that its more important for high corporate performance to determine the competitive strategy of a corporation fitting the external environment and internal structure. So its needed for successful cost-leadership or differentiation strategy to differentiate organizational function, resources, and various organizational factors. But there have been no methodologies or practical guidelines fitting competitive strategy, corporate structure, and external environment in sprite do service corporations growth. So, the study proved the fitness between competitive strategy and service operation structure in Airlines after selecting service structural elements necessary for strategic management.

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Frequency Dependend Network Equivalents to Electromagnetic Transient Simulation (주파수 의존 등가회로의 전자기 과도 현상 시뮬레이션)

  • Wang, Y.P.;Jo, K.S.;Kim, H.J.
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.592-593
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    • 2007
  • The complexity of modern power systems often makes it impractical to model it in its entirety for electromagnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). The advantage of using z-domain fitting is that it can be directly implemented in a digital simulation program without any loss of accuracy. Fitting in the s-domain always requires "discretizing" a continuous system and the inherent approximations. This paper presents z-domain rational function formulation and demonstrates the use of it for the assessment of the transient response of the Lower South Island of New Zealand.

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Application of Bootstrap Method to Primary Model of Microbial Food Quality Change

  • Lee, Dong-Sun;Park, Jin-Pyo
    • Food Science and Biotechnology
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    • v.17 no.6
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    • pp.1352-1356
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    • 2008
  • Bootstrap method, a computer-intensive statistical technique to estimate the distribution of a statistic was applied to deal with uncertainty and variability of the experimental data in stochastic prediction modeling of microbial growth on a chill-stored food. Three different bootstrapping methods for the curve-fitting to the microbial count data were compared in determining the parameters of Baranyi and Roberts growth model: nonlinear regression to static version function with resampling residuals onto all the experimental microbial count data; static version regression onto mean counts at sampling times; dynamic version fitting of differential equations onto the bootstrapped mean counts. All the methods outputted almost same mean values of the parameters with difference in their distribution. Parameter search according to the dynamic form of differential equations resulted in the largest distribution of the model parameters but produced the confidence interval of the predicted microbial count close to those of nonlinear regression of static equation.