• Journal of Magnetics
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• v.8 no.1
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• pp.45-49
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• 2003

We present a brief review of recent experimental and theoretical results on new magneto-optical phenomena in magnetic granular metal-insulator alloys with tunnel-type magnetoresistance, focusing on magnetorefractive effect and cubic nonlinear magneto-optics.

• Journal of the Chungcheong Mathematical Society
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• v.23 no.4
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• pp.773-784
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• 2010

The existence of solutions in Besov spaces for nonlinear heat equations having transcendental nonlinearity: $$\frac{\partial}{{\partial}t}u-{\Delta}u=F(u)$$ is investigated. In particular, it is proved the local existence and blow-up phenomena of the solutions in Besov spaces for nonlinear heat equations corresponding to two transcendental nonlinear functions $F(u){\equiv}{\mid}u{\mid}e^{u^2}$ and $F(u){\equiv}e^u$ of rapid growth.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.312-315
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• 2003

This paper deals with robust control problems of linear systems with matched nonlinear uncertainties. In order to handle the uncertainties, a Lyapunov min-max control approach can usually be adopted. By the way, the min-max control input is required to be switched and provokes chattering phenomena which limit the practical implementation. The magnitude of switching control input which cause chattering is dependent on the size of uncertainties. In this paper, it is shown that the magnitude of the min-max control input can be made small using a well-known disturbance observer technique and only considers the disturbance observing errors. The chattering phenomena can be reduced as small as possible by selecting a high diturbance observer gain. The simulations show that the min-max control with a disturbance observer can reduce chattering phenomena much smaller and guarantee much better robust performance rather than the one without a disturbance observer.

• Structural Engineering and Mechanics
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• v.72 no.5
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• pp.569-583
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• 2019

Tubular steel sections are widespread all over the world because of their strength and aesthetic appearance. Tubular steel members may exhibit local buckling such as elephant foot or overall buckling under extreme compression load. Recently, external bonding of fiber reinforced polymers (FRP) sheets for strengthening these members has been explored through experimental research. This paper presents three-dimensional nonlinear finite element analysis (FEA) to investigate the structural behavior of strengthening tubular steel members with FRP against local and overall buckling phenomena. Out-of-roundness and out-of-straightness imperfections were introduced to the numerical models to simulate the elephant foot and overall buckling, respectively. The nonlinear analysis preferences such as the integration scheme of the shell elements, the algorithm for solution of nonlinear equations, the loading procedure, the bisection limits for the load increments, and the convergence criteria were set, appropriately enough, to successfully track the sophisticated buckling deformations. The agreement between the results of both the presented FEA and the experimental research was evident. The FEA results demonstrated the power of the presented rigorous FEA in monitoring the plastic strain distribution and the buckling phenomena (initiation and propagation). Consequently, the buckling process was interpreted for each mode (elephant foot and overall) into three sequential stages. Furthermore, the influence of FRP layers on the nonlinear analysis preferences and the results was presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.7
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• pp.845-850
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• 2015

Love which is one of the emotional of mankind, has been studied in sociology and psychology as a matter of great concern. Through such a research, the researchers have provided the basic mathematical model for love model, we cannot find nonlinear characteristics through the basic love model. Therefore, in this paper, in order to find nonlinear behaviors in the basic love model, we apply external force to the basic love model. Then we confirm the existence of nonlinear behaviors through time series and phase portrait. We also confirm that this nonlinear behaviors have the periodic doubling, chaotic phenomena and periodic process which are very similar to typical chaotic occurrence phenomena.

• Journal of the Chungcheong Mathematical Society
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• v.31 no.3
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• pp.287-308
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• 2018

This paper deals with blow-up phenomena for an initial boundary value problem of a quasilinear parabolic equation with time-dependent coefficient in a bounded star-shaped region under nonlinear boundary flux. Using the auxiliary function method and differential inequality technique, we establish some conditions on time-dependent coefficient and nonlinear functions for which the solution u(x, t) exists globally or blows up at some finite time $t^*$. Moreover, some upper and lower bounds for $t^*$ are derived in higher dimensional spaces. Some examples are presented to illustrate applications of our results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.1
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• pp.7-15
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• 2002

The paper proposes the characteristics analysis for a Transverse flux type Switched Reluctance Motor(TSRM) considering the nonlinear magnetic phenomena. To investigate the nonlinear parameters of magnetic equivalent circuit, the designed TSRM is analyzed by the 2D and 3D finite element method as functions of input current and angular displacement. On the base of FEM analysis results, the current, torque, back EMF and output power wave of TSRM are simulated from the motion equation by MATLAB/Simulink. The simulated performance characteristics for a 4-phase, 24-pole TSRM are verified by experimental results of a prototype TSRM.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.1
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• pp.109-141
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• 1998

Many processes in the industrial realm exhibit sstochastic and nonlinear behavior. Consequently, an intelligent system must be able to nonlinear production processes as well as probabilistic phenomena. In order for a knowledge based system to control a manufacturing processes as well as probabilistic phenomena. In order for a knowledge based system to control manufacturing process, an important capability is that of prediction : forecasting the future trajectory of a process as well as the consequences of the control action. This paper examines the robustness of data mining tools under varying levels of noise while predicting nonlinear processes, includinb chaotic behavior. The evaluated models include the perceptron neural network using backpropagation (BPN), the recurrent neural network (RNN) and case based reasoning (CBR). The concepts are crystallized through a case study in predicting a chaotic process in the presence of various patterns of noise.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.239-243
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• 1992

We have investigeted the interference phenomena of the second harmonic waves of Nd:YAG laser generated at KDP single crystals and the nitrogen CARS signals. To get the phase difference between the successively generated nonlinear optical signals, a phase shifting unit made of BK-7 glass and a high pressure gas cell are used. Coherence lengths of several samples for the nonlinear signals are measured. Adjusting the thickness of the phase shifting unit where the CARS signals make destructive interference completely, the CARS spectrum of nitrogen suppressed over wide wavelength range is obtained. Also, we have observed the change in degree of suppression of the spectrum for the variation of the thickeness of the phase shifting unit.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.11
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• pp.873-881
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• 2002

The fluid induced vibration (FIV) phenomena of an equivalent airfoil system of MAV have been investigated in low Reynolds number flow region. Unsteady flows with viscosity are computed using two-dimensional incompressible Navier-Stokes equations. The present fluid/structure interaction analysis is based on one of the most accurate computational approach with computational fluid dynamics (CFD) and computational structural dynamics (CSD) techniques. The highly nonlinear fluid/structure interaction phenomena due to severe flow separations have been analyzed for the low Reynolds region that has a dominancy of flow viscosity. The effects of Reynolds number and initial angle of attack on the fluid/structure coupled vibration instability are shown and the qualitative trend of FIV phenomenon is investigated.