• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.311-314
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• 2003

In radar tracking, since the sensor measures range, azimuth and elevation angle of a target, the measurement equation is nonlinear and the extended Kalman filter (EKF) is applied to nonlinear estimation. The conventional EKF has been widely used as a nonlinear filter for radar tracking, but the considerably large measurement error due to the linearization of nonlinear function in highly nonlinear situations may deteriorate the performance of the EKF. To solve this problem, a fuzzy-model-based Kalman filter (FMBKF) is proposed for radar tracking. The FMBKP uses a local model approximation based on a TS fuzzy model instead of a Jacobian matrix to linearize nonlinear measurement equation. The hybrid GA and RLS method is used to identify the premise and the consequent parameters and the rule numbers of this TS fuzzy model. In two-dimensional radar tracking problem, the proposed method is compared with the conventional EKF.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 추계 학술대회 학술발표 논문집
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• pp.129-132
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• 2003

This paper proposes a novel and efficient intelligent digital redesign technique for a Takagi-Sugeno (TS) fuzzy system. The term of intelligent digital redesign involves converting an existing analog fuzzy-model-based controller into an equivalent digital counterpart in the sense of state matching. In this paper, we suggest the discretization method based on the dual-rate sampling approximation is first proposed, and then attempt to globally match the states of the overall closed-loop TS fuzzy system with the pre-designed analog fuzzy-model-based controller and those with the digitally redesigned fuzzy-model-based controller. To show the feasibility and the effectiveness of the proposed method, a computer simulation is provided.

• 한국유체기계학회 논문집
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• 제12권1호
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• pp.7-15
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• 2009

A study is made of thermal plume flow model for the development of helicopter simulator over the forest fire. For the numerical analysis, a line fire model with Boussinesq fluid approximation, which is idealized by the spreading shape of forest fire on the ground, is adopted. Comparing full 2-D and 3-D numerical solutions with 2-D similarity solution, it has been built a new model that is useful for temperature prediction along the symmetric vertical axis of fire model for both cases of laminar and turbulent flow.

• Journal of the Korean Data and Information Science Society
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• 제17권2호
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• pp.543-557
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• 2006

This paper is concerned with the applicability of the chi-square approximation to the six disparity statistics: the Pearson chi-square, the generalized likelihood ratio, the power divergence, the blended weight chi-square, the blended weight Hellinger distance, and the negative exponential disparity statistic. Three dimensional contingency tables of small and moderate sample sizes are generated to be fitted to all possible hierarchical log-linear models: the completely independent model, the conditionally independent model, the partial association models, and the model with one variable independent of the other two. For models with direct solutions of expected cell counts, point estimates and confidence intervals of the 90 and 95 percentage points of six statistics are explored. For model without direct solutions, the empirical significant levels and the empirical powers of six statistics to test the significance of the three factor interaction are computed and compared.

• 한국공작기계학회논문집
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• 제10권3호
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• pp.1-6
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• 2001

An analytical thermal model of HESG(higt efficiency speed grinding) is presented, in which the heat flux to workpiece in grinding zone is modeled as time dependent and moves along a slope decided by contact chord(approximation of con-tact arc). By matching the maximum surface temperature of workpiece derived from this model to the maximum surface temperature of grinding wheel composite as done in Lavins simple thermal model, the relation of maximum surface tem-perature and energy partition of workpiece to grinding speed is obtained. In high speed grinding, as wheel speed increases, energy partition decreases with no regard to table speed.

• 부모자녀건강학회지
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• 제17권1호
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• pp.37-45
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• 2014

Purpose: This study aimed to review measurements of environmental health behavior and assess the construct validity of Environmental Health Engagement Profile (EHEP) through confirmatory factor analysis. Methods: The literature review was performed for selection of measurements. Confirmatory factor analysis with AMOS 19.0 was used for validation of EHEP. Results: The model fitness was not appropriate in the one-factor model; $x^2=91.11$ (df=5, p<.001), Comparative Fit Index (CFI)=8.19, Non Normed Fit Index (NNFI)=6.39, and Root Mean Square Error of Approximation (RMSEA)=0.20. The model fitness was appropriate in the two-factor model; $x^2=3.19$ (df=1, p=.074), CFI=9.95, NNFI= 9.71, RMSEA=0.07. A modification of scale was found to be the most suitable for use in the investigation of environmental health behavior. Conclusion: This study confirms that a two-factor model underlies the concept of environmental health behavior. The review of measurements can help nurses and researchers to assess the environmental health behaviors.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권3호
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• pp.184-189
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• 2006

This paper deals with a fractional model reduction for T-S fuzzy systems with time varying delayed states. A contractive coprime factorization of time delayed T-S fuzzy systems is defined and obtained by solving linear matrix inequalities. Using generalized controllability and observability gramians of the contractive coprime factor, a balanced state space realization of the system is derived. The reduced model will be obtained by truncating states in the balanced realization and an upper bound of model approximation error is also presented. In order to demonstrate efficacy of the suggested method, a numerical example is performed.

• 품질경영학회지
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• 제34권3호
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• pp.19-30
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• 2006

For highly reliable products, it is difficult to assess the lifetime of the products with traditional life tests. Accordingly, a recent approach is to observe the performance degradation of product during the test rather than regular failure time. This study compares performances of three methods(i.e. the approximation, analytical and numerical methods) to estimate the parameters and quantiles of the lifetime when the time-to-failure distribution follows Weibull and lognormal distributions under a random coefficient degradation rate model. Numerical experiments are also conducted to investigate the effects of model error such as measurements in a random coefficient model.

• 대한전자공학회논문지
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• 제24권6호
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• pp.948-955
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• 1987

The model reduction method of the high order linear time invariant systems is proposed. The continuous fraction expansion of Auxiliary denominator polynomial is used to obtain denominator polynomial of the reduced order model, and the numerator polynomial of the reduced order model is obtained by equating the first some moments of the original and the reduced order model, using simplified moment function. This methiod does not require the calculation of the reciprocal transformation which should be calculated in Routh approximation, furthemore the stability of the reduced order model is guaranted if original system is stable. Responses of this method showed us good characteristics.

• 동력기계공학회지
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• 제19권3호
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• pp.55-62
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• 2015

This paper discusses a new model for investigating the micro-mechanical behavior of beam-like structures composed of various elastic moduli and complex geometries varying through the cross-sectional directions and also periodically-repeated along the axial directions. The original three-dimensional problem is first formulated in an unified and compact intrinsic form using the concept of decomposition of the rotation tensor. Taking advantage of two smallness of the cross-sectional dimension-to-length parameter and the micro-to-macro heterogeneity and performing homogenization along dimensional reduction simultaneously, the variational asymptotic method is used to rigorously construct an effective zeroth-order beam model, which is similar a generalized Timoshenko one (the first-order shear deformation model) capable of capturing the transverse shear deformations, but still carries out the zeroth-order approximation which can maximize simplicity and promote efficiency. Two examples available in literature are used to demonstrate the consistence and efficiency of this new model, especially for the structures, in which the effects of transverse shear deformations are significant.