• Journal of Power Electronics
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• v.14 no.3
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• pp.549-563
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• 2014

In this paper, the speed regulation problem of permanent synchronous motor (PMSM) systems under the vector control framework is studied. A model reference adaptive controller (MRAC) based on the Lyapunov stability theory is first designed. Since the standard MRAC method provides poor disturbance rejection performance in the case of strong disturbances, a composite control method which combines the MRAC method and the disturbance estimation method, called the MRAC+ESO method, is proposed. An extended state observer (ESO) is introduced to estimate the lumped disturbances. The obtained estimated value acts as a feedforward compensation term to the MRAC controller. A stability analysis of the composite control method is given. Simulation and experimental results are presented and compared to show the effectiveness of the proposed control method.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.161-169
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• 2006

Load representation has a significant impact on power system analysis and control results. In this paper, composite load models are developed based on on-line measurement data from a practical power system. Three types of static-dynamic load models are derived: general ZIP-induction motor model, Exponential-induction motor model and Z-induction motor model. For the dynamic induction motor model, two different third-order induction motor models are studied. The performances in modeling real and reactive power behaviors by composite load models are compared with other dynamic load models in terms of relative mismatch error. In addition, numerical consideration of ill-conditioned parameters is addressed based on trajectory sensitivity. Numerical studies indicate that the developed composite load models can accurately capture the dynamic behaviors of loads during disturbance.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.173-174
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• 2006

The power infrastructure defense system monitor and control a power system with parameters of a power system such as voltage, phasor angle, frequency and power flow which are measured at the same instance. For this, synchronized phasor measurement based on the GPS(Global Positioning System) is necessary. PMU(Phasor Measurement Unit) measures synchrophasor and transmits it to the power infrastructure defense system. For this communication, IEEE H37.118 defines a communication message format and measurement concept and we extend the protocol to transmit disturbance data. The synchrophasor data can be sent at various rates and there are several options for phasor information sent in the synchrophasor message. In this paper, we develop software that simulate communication between the power infrastructure defense system and PMU to annalize the traffic.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1131-1136
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• 2005

For the accurate measurement of acoustic properties of a surface, efforts have been made to reduce errors caused by external disturbance. If the reflection coefficient is considered as a transfer function between reflected wane and incident wave, the causality is required between them and the reflection coefficient should be of minimum phase. In this thesis, the minimum phase condition is applied to measure correct reflection coefficient. The reflection coefficient is approximated as a rational function In the Z domain by minimizing the sum square error. Then the minimum phase reflection coefficient is reconstructed using the distribution of poles and zeros of the reflection coefficient model.

• International Journal of Railway
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• v.4 no.1
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• pp.19-27
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• 2011

Many studies for improving the railway vehicle's performance and comfort such as speed, weight and noise are currently in progress. Improving the structural characteristics of the vehicle for greater noise insulation is considered important for reducing disturbance due to noise, but measuring transmission loss entails large costs. This study explores an alternative method for estimating and measuring the railway vehicle's transmission loss that involves on applying the numerical analysis coupled with scaled reverberation chamber measurement. The transmission loss measurement using scaled reverberation chamber was performed after the compensation value was found through 1mm thickness(1t) specimen. For numerical analysis, a commercially available acoustics solver VA ONE was used. The proposed method is found to lead to transmission loss measurement comparable to the measurements based on large-scale reverberation chamber. Thus, it can be argued that a reliable method has been developed for measuring railway vehicle's transmission loss.

• The Journal of Internal Korean Medicine
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• v.39 no.4
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• pp.802-813
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• 2018

This case report describes a patient with olivopontocerebellar atrophy accompanied by sleep disorder and gait disturbance whose condition was improved by treatment with Korean medicine. The 61-year-old woman, who was diagnosed with olivopontocerebellar atrophy (Multiple Systemic Atrophy-Cerebellum), was admitted to hospital twice and treated with Korean medicine (acupuncture and herbal medicine) and rehabilitation. The Korean medicine was Gwibiondam-tang-gami and Jaeumgeonbi-tang-gami. Clinical symptoms were assessed by the Modified Bathel index, functional independent measurement, Berg balance scale, and Unified Multiple System Atrophy rating scale. A brain MRI at the one-year follow up after onset showed similar progress but clinical symptoms were improved after treatment, and the evaluation index score increased. Multiple system atrophy, a type of degenerative neurological disease, has no targeted treatment. In this situation, although this report describes a single case, Korean medicine treatment could provide a meaningful improvement in the sleep disturbance and gait disorder symptoms of patients with olivopontocerebellar atrophy.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.23-30
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• 2015

This study analyzed degree of disturbance, using specimens by laboratory test with large block specimens and piston samplers collected from the Korea's two typical soft ground districts: South coast Gwangyang and Yangsan. To assess the characteristics of compression index of laboratory test incurred by disturbance, the compression index of laboratory test was compared with the back analysis compression index resulting from the analysis of the measured settlement. The analysis of specimen disturbance of the laboratory test results with the piston specimens of the two districts found that the qualities of most specimens were poor and the settlement predicted by the laboratory test compression index was underestimated. The analysis of test material taken from nearby areas proved that the disturbance degrees of large block specimens were lower than that of the piston specimens. The hyperbolic method, Hoshino method, Asaoka method, and ${\sqrt{S}}$ method, all of which are predictive methods using measured settlement, were employed to reach a conclusion that reliabilities of each predictive method except predictive material of a few points were the same. To compensate the disturbance effects on compression index of the piston specimens, we suggested a new modification formula that estimates compression index of piston specimens, using Schmertmann's corrected compression index, and back analysis compression index from the analysis of predictive settlement.

• Transactions on Control, Automation and Systems Engineering
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• v.1 no.1
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• pp.1-7
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• 1999

This paper gives a simulation study of a new fuzzy logic control(FLC) approach for the mold level control in continuous casting processes. The proposed FLC is PID type hybridizing the conventional fuzzy PI control and Fuzzy PD control with a simplified design scheme. It is shown that, compared with the conventional control, this new control strategy can achieve superior performance for steady-state response and is more robust against process parameter variations and disturbances.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1068-1072
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• 1991

This paper presents a decentralized model reference adaptive control scheme for an interconnected continuous linear system composed of a number of single-input single-output subsystems in which outgoing interactions pass through the measurement channel and are subject to bounded external disturbance. The scheme can treat the unknown strength of interactions as well as the uncertainty of subsystems.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.2
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• pp.47-57
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• 1989

This paper aims at describing a series development of the electrical machine, by using the Similarity Theory. The character of the electrical machine defined as the Four Terminal Network of the electrical and mechanical energy transmission system, and the analogy theory of the modelmachine can be developed by the Four Termianl System. Also the Restriction Parameter and Disturbance Parameter can be founded by the comparative data of the developed machine that is the character of the theory and measurement.