• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1158-1168
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• 1994

A variable structure control scheme(VSCS) with sliding mode that can be applied to the process with input/output(I/O) delay is proposed and its control performances is evaluated. The proposed VSCS with and output feedback scheme comprises a variable structure controller, a servo dynamic for tracking the set-poing, and a Smith predictor for compensating the effects of time delay. The robustness against the parameter variations and external disturbances can be achieved by the proposed VSCS even when the controlled process includes I/O delay. And the desired transient response is obtained by simple adjustment of the coefficients of the switching surface equation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.8
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• pp.883-892
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• 1992

In order to remove the assumption of full state availability which is one of the major difficulties with the practical realization of variable structure control system (VSCS), an output feedback variable structure control scheme for multivariable systems is proposed. The proposed output feedback VSCS is composed of a switching surfaces with dynamic structure and a new output feedback control input that can be constructed by using conventional output feedback control input design methodologies. With the proposed scheme, the practical realization of VSCS for the systems with unmeasurable states and for high order systems that conventional schemes cannot be applied is possible. Simulation results show that proposed scheme is a viable method to achieve the desired control performance, for example, good transient response, robustness against process parameter variations and external disturbance without measuring all the state variables.

• Journal of Information Processing Systems
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• v.8 no.3
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• pp.421-436
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• 2012

Different types of fingerprint detection algorithms that are based on extraction of minutiae points are prevalent in recent literature. In this paper, we propose a new algorithm to locate the virtual core point/centroid of an image. The Euclidean distance between the virtual core point and the minutiae points is taken as a random variable. The mean, variance, skewness, and kurtosis of the random variable are taken as the statistical parameters of the image to observe the similarities or dissimilarities among fingerprints from the same or different persons. Finally, we verified our observations with a moment parameter-based analysis of some previous works.

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.70-79
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• 1997

This paper presents a study on the fuzzy linguistic variable based approach for safety assessment of human body in ELF electromagnetic field considering power system states. To cope with the demand in modern industry, the power system becomes larger in scale, higher in voltage. The advent of high voltage system has increased the relative importance of field effects. The analysis of ELF electromagnetic field based on Quasi-Static Method is introduced while the power system is included to model the expected and/or unexpected uncertainty caused by the load fluctuation and parameter changes. In order to analyze the power system, Monte Carlo simulation method and contingency analysis method are adopted in normal state and alert state, respectively. In the safety assessment of human body, the approach based on fuzzy linguistic variable is employed to overcome the shortcomings resulting from a crisp set concept. The suggested scheme is applied to a sample system(modified IEEE 14 bus system) to validate the usefulness.

• Transactions of Materials Processing
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• v.13 no.6 s.70
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• pp.535-539
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• 2004

Although magnesium has high potential for structural material due to the lightweight and high specific strength, the structural application has been limited by the low ductility at room temperature. The reason of the poor ductility is few activated slip systems of magnesium (HCP structure) during deformation. As temperature increases, however, additional non-basal slip systems are incorporated to exhibit higher ductility comparable to aluminum. In the present study, a series of tensile tests of Mg-Al alloy has been carried out to study deformation behavior with temperature variation. Analysis of load relaxation test results based on internal variable approach gave information about relationship between the micromechanical character and corresponding deformation behavior of magnesium. Especially, the material parameter, p representing dislocation permeability through barriers was altered from 0.1 to 0.15 as the non-basal slip systems were activated at high temperature.

• Advances in aircraft and spacecraft science
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• v.7 no.2
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• pp.115-134
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• 2020

This paper proposes a bending analysis for a functionally graded piezoelectric (FGP) plate through utilizing a two-variable shear deformation plate theory under simply-supported edge conditions. The number of unknown functions used in this theory is only four. The electric potential distribution is assumed to be a combination of a cosine function along the cartesian coordinate. Applying the analytical solutions of FGP plate by using Navier's approach and the principle of virtual work, the equilibrium equations are derived. The paper also discusses thoroughly the impact of applied electric voltage, plate's aspect ratio, thickness ratio and inhomogeneity parameter. Results are compared with the analytical solution obtained by classical plate theory, first-order-shear deformation theory, higher-order shear deformation plate theories and quasi-three-dimensional sinusoidal shear deformation plate theory.

• Earthquakes and Structures
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• v.10 no.3
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• pp.681-697
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• 2016

The model of two-temperature magneto-thermoelasticity for a non-simple variable-thermal-conductivity infinitely-long solid cylinder is established. The present cylinder is made of an isotropic homogeneous thermoelastic material and its bounding plane is traction-free and subjected to a time-dependent temperature. An exact solution is firstly obtained in Laplace transform space to obtain the displacement, incremental temperature, and thermal stresses. The inversion of Laplace transforms has been carried out numerically since the response is of more interest in the transient state. A detailed analysis of the effects of phase-lags, an angular frequency of thermal vibration and the variability of thermal conductivity parameter on the field quantities is presented.

• Earthquakes and Structures
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• v.13 no.2
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• pp.201-209
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• 2017

This work aims to analyze the thermo-viscoelastic interaction in an orthotropic solid cylinder. The medium is considered to be variable thermal conductivity and subjected to temperature pulse. Analytical solution based on dual-phase-lags model with Voigt-type for behavior of viscoelastic material has been effectively proposed. All variables are deduced using method of Laplace transforms. Numerical results for different distribution fields, such as temperature, displacement and stress components are graphically presented. Results are discussed to illustrate the effect of variability thermal conductivity parameter as well as phase-lags and viscoelasticity on the field quantities. Results are obtained when the viscosity is ignored with and without considering variability of thermal conductivity. A comparison study is made and all results are investigated.

• Computers and Concrete
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• v.23 no.5
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• pp.303-309
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• 2019

This study investigates axisymmetric fractional vibration of an isotropic hyperelastic semi-linear thin disc with a view to examine effects of finite deformation associated with the material of the disc and effects of fractional vibration associated with the motion of the disc. The generalized three-dimensional equation of motion is reduced to an equivalent time fraction one-dimensional vibration equation. Using the method of variable separable, the resulting equation is further decomposed into second-order ordinary differential equation in spatial variable and fractional differential equation in temporal variable. The obtained solution of the fractional vibration problem under consideration is described by product of one-parameter Mittag-Leffler and Bessel functions in temporal and spatial variables respectively. The obtained solution reduces to the solution of the free vibration problem in literature. Finally, and amongst other things, the Cauchy's stress distribution in thin disc under finite deformation exhibits nonlinearity with respect to the displacement fields whereas in infinitesimal deformation hypothesis, these stresses exhibit linear relation with the displacement field.

• Steel and Composite Structures
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• v.38 no.4
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• pp.447-462
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• 2021

In this work, we consider a problem in the context of thermoelectric materials with memory-dependent derivative for a half space which is assumed to have variable thermal conductivity depending on the temperature. The Lamé's modulii of the half space material is taken as a function of the vertical distance from the surface of the medium. The surface is traction free and subjected to a time dependent thermal shock. The problem was solved by using the Laplace transform method together with the perturbation technique. The obtained results are discussed and compared with the solution when Lamé's modulii are constants. Numerical results are computed and represented graphically for the temperature, displacement and stress distributions. Affectability investigation is performed to explore the thermal impacts of a kernel function and a time-delay parameter that are characteristic of memory dependent derivative heat transfer in the behavior of tissue temperature. The correlations are made with the results obtained in the case of the absence of memory-dependent derivative parameters.