• Journal of IKEEE
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• v.22 no.3
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• pp.605-612
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• 2018

In this paper, a new method for linear sweeping of wavelength swept laser has proposed, and the linear sweeping of 1kHz speed and 80nm range has realized by using this method. The proposed requires only one-shot calibration in the early stage on a wave pattern applied to FFP-TF. This makes the problem with nonlinear swept lasers like a cumbersome and time-consuming signal processing brought on by every recalibration to be resolved.

• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.813-829
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• 2011

In this article, we present a numerical scheme for solving singularly perturbed (i.e. highest -order derivative term multiplied by small parameter) Burgers-Huxley equation with appropriate initial and boundary conditions. Most of the traditional methods fail to capture the effect of layer behavior when small parameter tends to zero. The presence of perturbation parameter and nonlinearity in the problem leads to severe difficulties in the solution approximation. To overcome such difficulties the present numerical scheme is constructed. In construction of the numerical scheme, the first step is the dicretization of the time variable using forward difference formula with constant step length. Then, the resulting non linear singularly perturbed semidiscrete problem is linearized using quasi-linearization process. Finally, differential quadrature method is used for space discretization. The error estimate and convergence of the numerical scheme is discussed. A set of numerical experiment is carried out in support of the developed scheme.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.621-626
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• 1985

Unsteady groundwater flow in a three-layer unconfined aquifer has been studied theoretically and experimentally. Two different methods have been used in solving the governing equations of the flow, the nonlinear partial differential equations; (1) The governing equations are linearized for each layer and approximate solutions are obtained. (2) The governing equations are transformed to nonlinear ordinary differential equations, which are solved numerically by Runge-Kutta procedure. Fine, middle sized and coarse sands are used in the experiments. It is found that the solutions from the method(2) ( the reduction of partial differential equations to ordinary differential equations) give better agreement with the experimental results than the solution from the method(1).

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.103-108
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• 2003

In this paper, the current lead for superconducting device is studied by numerical method. The current lead is cooled by surrounded $N_{2}$ gas by natural convection. The heat conduction equation for current lead and boundary layer equation for $N_{2}$ gas must be solved simultaneously. The boundary layer equation for $N_{2}$ gas is highly nonlinear for varied temperature of current lead. So the linearization method is adopted for simplicity. Numerical results using natural convection cooling are compared with the conventional cooling methods such as conduction cooling and vapor cooling methods. The main difference of natural convection cooing is the non-zero temperature gradient at the top of current lead for the minimum heat dissipation into superconducting devices. For the optimized conduction-cooling and vapor-cooling current leads, the temperature gradient at the top of current lead is zero. Also, the heat flow at the cold end is much smaller than conduction cooling case.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1594-1601
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• 2014

In this paper, we propose the LQ servo control method for the automatic train control of urban rail vehicle. Structures of the conventional PID control and LQ servo controller are compared in order to demonstrate the simplicity of the proposed controller which doesn't have zeros of the closed loop systems. The energy consumption is dealt with as an object function to be minimized, which consists of the quadratic performance indices for optimal control with the input of the feedback linearization. The effectiveness of the proposed method is shown by the practical example, compared with the conventional PD controller.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.1
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• pp.33-44
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• 1989

A controller disign method is proposed for multivariable nonlinear stochastic systems with hard nonlinearities such as Coulomb friction, backlash and saturation. In order to take the nonlinearities into account statistical linearization techniques are used. And multi- variable pole placement techniques are applied to design controller for the statistically linearized multivariable systems. The basic concept of the controller design method is to solve two coupled equations, characteristic equation and Lyapunov equation, simultaneously and iteratively for statistically linearized multivariable stochastic systems. An aircraft with saturation serves as a design example. The design example illustrates the influence of nonlinear effects. The results of the analysis are compared to Monte Carlo simulation to test their accuracy.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2073-2075
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• 1998

A cylindrical type Linear Pulse Motor (LPM) was designed as a linear motion actuator. In this paper, it is mentioned the mechanical design method of the LPM. It was designed as a prototype to estimate a new linearization control method for the nonlinear thrust force which is caused by the variable reluctance of the LPM. The designed LPM is determined a variable reluctance type to except the term of permanent magnetic force. The concreted figures and the dimensions will be described.

• Computers and Concrete
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• v.1 no.2
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• pp.131-150
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• 2004

We present in this work a coupled phenomenological chemo-mechanical model that represents the degradation of concrete-like materials. The chemical behaviour is described by the nowadays well known simplified calcium leaching approach. And the mechanical damage behaviour is described by a continuum damage model which involves the gradient of the damage quantity. The coupled nonlinear problem at hand is addressed within the context of the finite element method. For the equation governing the calcium dissolution-diffusion part of the problem, special care is taken to treat the highly nonlinear calcium conductivity and solid calcium functions. The algorithmic design is based on a Newton-type iterative scheme where use is made of a recently proposed relaxed linearization procedure. And for the equation governing the damage part of the problem, an augmented Lagrangian formulation is used to take into account the damage irreversibility constraint. Finally, numerical simulations are compared with experimental results on cement paste.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.7
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• pp.32-39
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• 1996

In this paper, we describe the algorithm which controls an unknown nonlinear system with multilayer neural network. The multilayer neural netowrk can be used to approximate any continuous function to any desired degree of accuracy. With the former fact, we approximate unknown nonlinear function on the nonlinear system by using of multilayer neural netowrk. The weights on the hidden layer of multilayer neural network are updated by gradient method. The weight-update rule on the output layer is derived to satisfy lyapunov stability. Also, we obtain secondary controller form deriving step. The global control system consists of controller using feedback linearization method and secondary controller is order to satisfy layapunov stability. The proposed control algorithm is verified through computer simulation.

• Journal of Navigation and Port Research
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• v.33 no.9
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• pp.629-634
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• 2009

Vessels stability problems need to resolve the nonlinear mathematical models of rolling motion. For nonlinear systems subjected to random excitations, there are very few special cases can obtain the exact solutions. In this paper, the specific differential equations of rolling motion for intact ship considering the restoring and damping moment have researched firstly. Then the partial stochastic linearization method is applied to study the response statistics of nonlinear ship rolling motion in beam seas. The ship rolling nonlinear stochastic differential equation is then solved approximately by keeping the equivalent damping coefficient as a parameter and nonlinear response of the ship is determined in the frequency domain by a linear analysis method finally.