• Journal of Korean Society for Quality Management
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• v.32 no.4
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• pp.242-251
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• 2004

Several statistical methods are introduced 1=o analyze the accelerated failure time data. Most frequently used method is the log-linear approach with parametric assumption. Since the accelerated failure time experiments are exposed to many environmental restrictions, parametric log-linear relationship might not be working properly to analyze the resulting data. The models proposed by Buckley and James(1979) and Stute(1993) could be useful in the situation where parametric log-linear method could not be applicable. Those methods are introduced in accelerated experimental situation under the thermal acceleration and discussed through an illustrated example.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.491-493
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• 1999

In this paper, we consider the design of robust pole assignment for linear system. Considered uncertainty is time-varying uncertainty. Based on Lyapunov stability theorem and linear matrix inequality(LMI) we present the design result for pole assignment. Finally, we give some numerical examples to show the applicability and usefulness of our presented results.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.8
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• pp.818-822
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• 2009

In this paper, we consider a decentralized observer design problem for fault detection in large-scaled linear time-invariant systems. Since the fault detection residual is desired to be sensitive on the fault, we use the H_ index performance criterion. Sufficient conditions for the existence of such an observer is presented in terms of linear matrix inequalities. Simulation results show the effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1236-1238
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• 1999

This paper presents an effect of cross magnetization to the generator simplified linear model which is used for multi-machine power systems. The formulae of reactances and time constant with saturation effect are presented. The simulation results show that cross magnetization has an effect which can not be ignored, to the reactances, time constant and eigenvalues in one machine infinite bus system of simplified linear model.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.83.5-83
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• 2002

Perspective dynamical systems arise in machine vision, in which only perspective observation is available, and the essential problem is to estimate the state and /or unknown parameters for a moving rigid body based on the observed information. This paper proposes and studies a Luenberger-type observer for perspective tim e-varying linear systems. In particular, assuming a given perspective time-varying linear system to be Lyapunov stable and to satisfy some sort of observability condition, it is shown that the estimation error converges exponentially to zero. Finally, a simple numerical exam pie is presented to illustrate the result obtained.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2016-2018
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• 2002

An exact solution of the lossy linear tapered transmission line is derived. As its application, a simple design method of the quasi non-distortion lossy linear tapered transmission line in the time domain is described. A design example is presented to show the validity and usefulness of the method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1434-1439
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• 2008

Numerical methods for solving the state feedback control problem of linear time invariant system are presented in this paper. The methods are based on Haar wavelet approximation. The properties of Haar wavelet are first presented. The operational matrix of integration and its inverse matrix are then utilized to reduce the state feedback control problem to the solution of algebraic matrix equations. The proposed methods reduce the computation time remarkably. Finally a numerical example is illustrated to demonstrate the validity and applicability of the proposed methods.

• International Journal of Contents
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• v.10 no.1
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• pp.47-53
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• 2014

The paper considers the challenges involved in measuring the similarities between time series, such as time shifts and the mixture of frequencies. To improve recognition accuracy, we investigate an improved linear dynamical system for discovering prominent features by exploiting the evolving dynamics and correlations in a time series, as the quality of unsupervised pattern recognition relies strongly on the extracted features. The proposed approach yields a set of compact extracted features that boosts the accuracy and reliability of clustering for time series data. Experimental evaluations are carried out on time series applications from the scientific, socio-economic, and business domains. The results show that our method exhibits improved clustering performance compared to conventional methods. In addition, the computation time of the proposed approach increases linearly with the length of the time series.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.1037-1054
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• 2016

Structural parameter evaluation and external force estimation are two important parts of structural health monitoring. But the structural parameter identification with limited input information is still a challenging problem. A new simultaneous identification method in time domain is proposed in this study to identify the structural parameters and evaluate the external force. Each sampling point in the time history of external force is taken as the unknowns in force evaluation. To reduce the number of unknowns for force evaluation the time domain measurements are divided into several windows. In each time window the structural excitation is decomposed by orthogonal polynomials. The time-variant excitation can be represented approximately by the linear combination of these orthogonal bases. Structural parameters and the coefficients of decomposition are added to the state variable to be identified. The extended Kalman filter (EKF) is augmented and selected as the mathematical tool for the implementation of state variable evaluation. The proposed method is validated numerically with simulation studies of a time-invariant linear structure, a hysteretic nonlinear structure and a time-variant linear shear frame, respectively. Results from the simulation studies indicate that the proposed method is capable of identifying the dynamic load and structural parameters fairly accurately. This method could also identify the time-variant and nonlinear structural parameter even with contaminated incomplete measurement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1147-1152
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• 2013

In this study, the effect of an insulation coating on the start time of a linear region is theoretically investigated when an insulation-coated hot-wire is used for the transient hot-wire method (THWM). For this purpose, important parameters affecting the start time of the linear region are presented from an analytical solution of temperature-rise for an insulation-coated hot-wire. Furthermore, a critical time to ignore the influence of important parameters is studied. The theoretical results indicate that the effect of the insulation coating rapidly disappears with a decrease in the wire radius, coating thickness, thermal diffusivity of insulation material or an increase in the thermal conductivity of the insulation material. The results of this study will be helpful for selecting a proper start time of the linear region for the THWM using insulation-coated hot-wires.