• 한국해양학회지
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• v.21 no.3
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• pp.131-135
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• 1986

Conversion of energy from potential to kinetic form is considered when a step-like initial disturbance is released to reach a final steady state. For small amplitute disturbances, linearization can be made and it is proved analytically that the conversion factor (ratio of generated kinetic to loss in potential energies) asymptotically approaches to 1/3 as the horizontal scale of disturbances becomes large.

• Journal of the Korean Statistical Society
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• v.12 no.2
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• pp.81-90
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• 1983

The least squares estimator of disturbance variance in a regression model is biased under a serial correlation. Under the assumption of an AR(I), Theil(1971) crudely related the bias with the autocorrelation of the disturbances and the autocorrelation of the explanatory variable for a simple regression. In this paper we derive a relation which relates the bias with the autocorrelation of disturbances and the autocorrelation of explanatory variables for a multiple regression with improved precision.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.145-151
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• 2001

An extension of interaction matrix formulation to the problem of system and disturbance identification for a plant that is corrupter by both process and output disturbances is presented. With only an assumed upper bound on the order of the system and an assumed upper bound on the number of disturbance frequencies, it is shown that both the disturbance-free model and disturbance effect can be recovered exactly from disturbance-corrupted input-output data without direct measurement of the periodic disturbances. The rich information returned by the identification can be used by a performance-oriented model-based loaming or repetitive control system to eliminate unwanted periodic disturbances.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.3
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• pp.119-128
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• 2005

In this paper, an robust adaptive backstepping controller is proposed for the chaos system with disturbances. This controller will be applicable to the chaos system of strict-feedback form and utilize the saturation function for decreasing the effect of disturbances derived from unmodelled dynamics and external noise. It shows that backstepping algorithm can be used to solve the problems of nonlinear system very well and robust controller can be designed without the variation of adaptive law. Simulation results are provided to demonstrate the effectiveness of the proposed controller.

• Sleep Medicine and Psychophysiology
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• v.7 no.2
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• pp.79-83
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• 2000

Sleep disturbances are frequently associated with neurological disorders. Sleep disorders interfere with rehabilitation of patients with neurological disorders such as stroke and may increase the severity of their symptoms and recurrence rate of stroke. The treatment of sleep apnea syndrome is particularly important in managing patients with cerebral infarction of whom 50-80% have moderate to severe sleep apnea. Sleep apnea produces not only poor quality sleep but also excessive daytime sleepiness, fatigue and lack of energy. Sleep problems frequently found in patients with dementia are sleep-wake cycle abnormality, fragmentation of sleep, nocturnal insomnia, decreased slow wave sleep and REM sleep, and sleep disordered breathing. The management of sleep disturbances is very important for controlling symptoms such as nocturnal wandering and sundowning syndrome in patients with dementia. Parkinson's disease and epilepsy are other neurological disorders that may have sleep disturbances.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.330-339
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• 2015

Power quality (PQ) problems are becoming a big issue, since delicate complex electronic devices are widely used. We present a new denoising technique using discrete wavelet transform (DWT), where a modified correlation thresholding is used in order to reliably detect the PQ disturbances. We consider various PQ disturbances on the basis of IEEE-1159 standard over noisy environments, including voltage swell, voltage sag, transient, harmonics, interrupt, and their combinations. These event signals are decomposed using DWT for the detection of disturbances. We then evaluate the PQ disturbance detection ratio of the proposed denoising scheme over Gaussian noise channels. Simulation results also show that the proposed scheme has an improved signal-to-noise ratio (SNR) over existing scheme.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.391-393
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• 2005

This paper studies flicker evaluation considering power quality disturbance. A flicker problem with light device irritates human's eyes. Also, the flicker problem has an influence on adverse effect such as rolling device and rotating device. However, a study of flicker evaluation is not complete. A flicker is measured and evaluated at monitoring point. But we consider power quality disturbances such as voltage sag and transient that cause fault and inverter/breaker switching. Power quality disturbances affects flicker evaluation. A flicker evaluation index increases. Therefore, we consider power quality disturbances. We detect voltage sag and transient using wavelet and evaluate flicker without flicker index including power quality disturbances.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1245-1254
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• 2004

In this paper, we deal with a precise position synchronous control of four-axes system which is working under various load disturbances. Each axis driving system is consisted of a speed controller and an acceleration controller as an inner loop instead of conventional current control scheme. The acceleration control plays an important roll to suppress load disturbances quickly. Also, each axis is coupled by a maximum position synchronous error comparison to minimize position synchronous errors according to integration of speed differency. As a result, the proposed system enables precise synchronous control with good robustness against load disturbances during transient as well as steady state. The stability and robustness of the proposed system are investigated through its frequency characteristic and numerical simulations. Finally, experimental results under load disturbances demonstrate the effectiveness of the proposed control system fur four-axes position synchronous control.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.346-349
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• 1994

This paper is concerned with a motion control of a manipulator under parametric uncertainties and external disturbances. The parametric uncertainties are regarded as internally generated disturbances in the manipulator. Based on this idea, we formulate a model reference control problem with desired disturbance attenuation. The solution of this control problem not only reduces the worst-case effect on tracking error due to internal and external disturbances (combined disturbances) as much as possible, but also achieve optimal tracking when perturbations are absent. In order to solve the control problem which is formulated in this paper we reduce it to a constrained minmax cost control problem. A differential game theory is used to treat this constrained minmax cost control problem. The differential game theory leads to a sufficient condition for the global solvability of the model reference control problem with desired disturbance attenuation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.62.3-62
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• 2001

The predictive control is one of the nonlinear three-axis rotation methods. The desired trace of a satellite is pre-determined, and the control inputs are designed so that the satellite follows the ´predictive´ trace. The predictive control has been adapted to the research for the three-axis attitude control. In that case, the control variables are the quaternion represented the angular rates and attitude angles of the body about the three-axes. The objective of this paper is to propose to design a predictive controller for the three-axis attitude control under external disturbances. In order to do that, this paper proposes how to construct a predictive control law including disturbances and to discern them. The basic algorithm of the existent predictive control is partially modified, and the presumption and modeling of disturbances are performed ...