• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.11
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• pp.430-435
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• 1985

Using the constructive algorithm proposed by Brayton and Tong, we analyze the stability of a modified coupled-form digital filter with quantization and overflow nonlinearities, and find the regions in the parameter plane where the filter is globally asymptotically stable. In these regions, the absence of zero-input limit cycles is ensured. This constructive algorithm gives less conservative stability results than the application of Jury-Lee stability criterion does.

• Journal of Aerospace System Engineering
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• v.7 no.4
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• pp.27-35
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• 2013

Identifying the stability of rotor systems is prerequisite for clear determination of the parameter identification and safety, through which operating conditions may be rationally ascertained. For this purpose, the complex modal analysis of periodically time-varying system has been introduced by transforming the relation between periodic eigen-vectors and the corresponding adjoint vectors into the latent value problem. Stability investigation associated with modal features for rotor systems is performed using numerical simulation based upon the analysis model.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.95-97
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• 2004

This paper estimates Adaptive Resonance Theory 1(ART1) as a vigilance parameter of pattern clustering algorithm. Inherent characteristics of the model are analyzed. In particular the vigilance parameter ${\rho}$ and its role in classification of patterns is examined. Our estimates show that the vigilance parameter as designed originally does not necessarily increase the number of categories with its value but can decrease also. This is against the claim of solving the stability-plasticity dilemma. However, we have proposed a modified vigilance parameter estimate criterion which takes into account the problem of subset and superset patterns and stably categorizes arbitrarily many input patterns in one list presentation when the vigilance parameter is closer to one.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.401-411
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• 2001

This paper deals with the vibration analysis of the rectangular plates which are subjected to uniform in-plane stresses and supported on In-homogeneous Pasternak foundation. Two parametric foundation which Winkler foundation parameter and shear foundation parameter considered, is called by the Pasternak foundation. The values of Winkler foundation parameter of central and border zone of plate are chosen as k₁and k₂respectively, and the value of shear foundation is chosen as constant about all zone of plate. After composing global flexural stiffeness matrix, geometrical stiffeness matrix, mass matrix, and the stiffeness matrix of the Pasternak foundation, eigenvalue problems which are composed of these matrices are solved. The result shows that the shear foundation parameter must not be ignore when considering the stiffeness of foundation.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1934-1938
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• 1991

This paper proposes a robust model following control systems with nonlinear time varying plant. which realies good properties such as asymptotic stability, disturbance rejection and model-following with reduced sensitivity for plant parameter variation. The schemes do not incorporate any parameter identification algorithms, but the adaptation is realized through signal synthesis in a fixed parameter structure.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.4
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• pp.316-325
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• 1989

This paper is concerned with robust stabilization of single input or single output systems. Based on the region of non-destabilizing perturbations some approaches to design which allow the given of structured perturbation of plant parameters and their gradient optimization are given. These algorithms iteratively enlarge the stability hypershere in plant parameter space and can be used to design a controller to stabilize a plant subject to given ranges of parameter excursions.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.4
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• pp.273-280
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• 2021

The water resistance is important factor for sunscreen formulations. Generally a sunscreen cream was formulated by a water-in-oil (W/O) emulsion. In the W/O emulsion system, silicone oils are added to improve the texture of formulations. Silicone oils have low compatibility with organic sunscreen agent, causing problems with the stability in emulsion. In this study, the compatibility between various oils in the W/O emulsion was derived numerically using Hansen solubility parameter (HSP) at first. HSP is represented a dispersion degree, a polarity, and a hydrgen bond in a composition. In this study, various emulsions were prepared according to the types of oils with different HSP values and then monitored by a viscosity and morphology according to the time and temperature. The HSP values of components and the experimental results have similar activities for the stability of emulsions. HSP made it easy to select oil with high compatibility. When the compatibility of the oil phase in the W/O emulsion was high, the viscosity change over time was small. The stability was improved under the freeze-thaw cycle (-15 ℃ ~ 45 ℃). In the future, if the composition of the ingredients is optimized through HSP, it is expected that it will be helpful in the development of W/O type sunscreen formulations that are excellent in use and stability.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.393-397
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• 2003

This paper presents neural load torque observer tha used to deadbeat load torque observer and regulation of the compensation gun by parameter estimator. As a result, the response of PMSM follows that of the nominal plant. The load torque compensation method is compose of a neural deadbeat observer. To reduce of the noise effect, the post-filter, which is implemented by MA process, is adopted. The parameter compensator with RLSM (recursive least square method) parameter estimator is adopted to increase the performance of the load torque observer and main controller. The parameter estimator li combined with a high performance neural torque observer to resolve the problems. As a result, the proposed control system becomes a robust and precise system against the load torque and the parameter variation. A stability and usefulness, through the verified computer simulation, are shown in this paper

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.2
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• pp.127-136
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• 1989

This paper describes the parameter convergence properties of an adaptive system to identify a single-input single-output plant model. It is demonstrated that, by using power spectrum analysis, the persistency of excitation (PE) condition in order to guarantee the exponential stability of the adaptive control system can be transformed into the positive definite behavior for the auto-correlation function matrix of adaptive signal. The existence of parameter nominal values can be analyzed by this condition and the convergence rates of parameter are determined by examining the auto-correlation function. We may use the sufficient richness (SR) of input spectrum instead of the PE condition to analyze the parameter boundedness. It can be shown that the eigen values of the auto-correlation function are always related with adaptive gain, input amplitude and positions or numbers of input spectra. In each case, the variation of parameter convergence rate can be also verified.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.49-52
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• 2002

This paper presents neural load torque observer that used to deadbeat load torque observer and regulation of the compensation gain by parameter estimator. As a result, the response of PMSM follows that of the nominal plant. The load torque compensation method is compose of a neural deadbeat observer. To reduce of the noise effect, the post-filter, which is implemented by MA process, is adopted. The parameter compensator with RLSM (recursive least square method) parameter estimator is adopted to increase the performance of the load torque observer and main controller. The parameter estimator is combined with a high performance neural torque observer to resolve the problems. As a result, the proposed control system becomes a robust and precise system against the load torque and the parameter variation. A stability and usefulness, through the verified computer simulation, are shown in this paper.