• 한국농공학회지
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• 제45권5호
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• pp.117-125
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• 2003

Since the recorded information used for operation of a catchment modelling system contain errors that influence the calibration of catchment modelling system control parameter values, the accurate estimation of these parameters is difficult. Despite these influences, existing traditional calibration approaches focus only on achieving the best "curve fitting" between simulated and recorded data, and not on generic evaluation of control parameter values. This paper introduces an Early Stopping Technique which is aimed at avoiding the procedure of curve-fitting through monitoring improvements in the objective function used for assessing the optimal parameter set. Application of this approach to the calibration of SWMM (Storm Water Management Model) on the Centennial Park catchment in Sydney, Australia is outlined. outlined.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1166-1176
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• 2017

Estimation errors of the rotor speed and position in sensorless control systems of Permanent Magnet Synchronous Motors (PMSM) will lead to low efficiency and dynamic-performance degradation. In this paper, a parallel-type extended nonlinear observer incorporating the nominal parameters is constructed in the stator-fixed reference frame, with rotor position, speed, and the load torque simultaneously estimated. The stability of the extended nonlinear observer is analyzed using the indirect Lyapunov's method, and observer gains are selected according to the transfer functions of the speed and position estimators. Taking into account the parameter inaccuracies issue, explicit estimation error equations are derived based on the error dynamics of the closed-loop sensorless control system. An equivalent flux error is defined to represent the back Electromotive Force (EMF) error caused by the inaccurate motor parameters, and a compensation strategy is designed to suppress the estimation errors. The effectiveness of the proposed method has been validated through simulation and experimental results.

• Communications for Statistical Applications and Methods
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• 제29권5호
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• pp.533-545
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• 2022

Collection of data on several variables, especially in the field of medicine, results in the problem of measurement errors. The presence of such measurement errors may influence the outcomes or estimates of the parameter in the model. In classification scenario, the presence of measurement errors will affect the intrinsic cum summary measures of Receiver Operating Characteristic (ROC) curve. In the context of ROC curve, only a few researchers have attempted to study the problem of measurement errors in estimating the area under their respective ROC curves in the framework of univariate setup. In this paper, we work on the estimation of area under the multivariate ROC curve in the presence of measurement errors. The proposed work is supported with a real dataset and simulation studies. Results show that the proposed bias-corrected estimator helps in correcting the AUC with minimum bias and minimum mean square error.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2078-2081
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• 1997

IP speed controller is used as a main controller and it makes the system low overshoot and easy controllability. Load torque is estimated by Kalman filter algorithm and parameter controller is used against a rotor inertia negative variations. Parameter Controller (PC) is equipped with a torque observer implemented by software of a digital signal Processor. PC is a parameter controller which selects a moment of inertia J in responding to a load torque to control the system response.

• Communications for Statistical Applications and Methods
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• 제6권2호
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• pp.611-620
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• 1999

We shall propose several estimators and confidence intervals for the scale parameter in a uniform distribution with the presence of a generalized uniform outlier and obtain mean squared errors(MSE) for their proposed estimators. And we shall compare numerical MSE's for the proposed several estimators of the scale parameter. Also we shall compare numerically expected lengths of confidence intervals of the scale parameter in a uniform distribution with the presence of a generalized uniform outlier.

• 로봇학회논문지
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• 제11권4호
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• pp.248-255
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• 2016

Machining error makes the uncertainty of dimensional accuracy of the kinematic structure of a parallel robot system, which makes the uncertainty of kinematic accuracy of the end-effector of the parallel robot system. In this paper, the tendency of trajectory tracking error caused by the tolerance of design parameters of the parallel robot is analyzed. For this purpose, all the position errors are analyzed as the manipulator is moved on the target trajectory. X, Y, Z components of the trajectory errors are analyzed respectively, as well as resultant errors, which give the designer of the manipulator the intuitive and deep understanding on the effects of each design parameter to the trajectory tracking errors caused by the uncertainty of dimensional accuracy. The research results shows which design parameters are critically sensitive to the trajectory tracking error and the tendency of the trajectory tracking error caused by them.

• 응용통계연구
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• 제8권2호
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• pp.187-200
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• 1995

본 논문에서는 회귀모형에서의 오차항이 비선형시계열(nonlinear time series)을 따르는 경우에 오차항이 선형인지를 검정하는 방법에 대해서 연구하고 있다. 이를 위해서 회귀계수의 대표본 성질을 규명하고 잔차를 이용한 오차항의 선형성 검정통계량을 유도하고 그 성질을 연구해 보았다.

• Journal of the Korean Statistical Society
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• 제31권1호
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• pp.77-91
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• 2002

This paper considers a functional regression model with truncated errors in explanatory variables. We show that the ordinary least squares (OLS) estimators produce bias in regression parameter estimates under misspecified models with ignored errors in the explanatory variable measurements, and then propose methods for analyzing the functional model. Fully parametric frequentist approaches for analyzing the model are intractable and thus Bayesian methods are pursued using a Markov chain Monte Carlo (MCMC) sampling based approach. Necessary theories involved in modeling and computation are provided. Finally, a simulation study is given to illustrate and examine the proposed methods.

• Journal of applied mathematics & informatics
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• 제11권1_2호
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• pp.327-340
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• 2003

For motion analysis electromagnetic sensors are often used to measure positions and orientations of human subjects. It is observed from several experiments of the Ergonomics Research group that there exist systematic errors and unexpected serious distortions due to some metal masses in the test area. A calibration process is necessary to fix these errors. In this article three models are proposed to correct position measurement errors based on observations from calibration experiments.

• 한국정밀공학회지
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• 제20권9호
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• pp.40-46
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• 2003

Synchronizing errors between the spindle motor and the z-axis motor directly influences the cutting characteristics and the thread quality in tapping, because the tapping process is accomplished by synchronizing the movement of the z-axis with the revolutionary spindle motion. Generally synchronizing errors are decided by tile parameters of the servo system and commanded velocity. The excessive synchronizing errors which are induced by the parameter mismatch and high cutting velocity can cause tap breakage due to the abrupt increase of cutting torque or damage the thread accuracy by overcutting the already cut threads. In this paper, the influences of the synchronizing errors on the tapping characteristics in the ultra high-speed tapping will be described and a minimum level of synchronizing errors necessary to maintain the quality of the cut thread will be presented.