• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.27-27
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• 2000

The nonlinear observers are proposed for a nonlinear system. To improve the characteristics such as a stability, a convergence, and an H$\sub$$\infty$/ filter performance criterion, we utilize and H$\sub$$\infty$/ filter Riccati equation or a modified H$\sub$$\infty$/ filter Riccati equation with a freedom parameter. Using the Lyapunov, the characteristics of the observer are analyzed. Then the in-flight alignment for a strapdown inertial navigation system(SDINS) is designed using the observer proposed. Simulation results show that the observer with the modified H$\sub$$\infty$/ fitter Riccati equation effectively improve the performance of the in-flight alignment.

• 대한기계학회논문집B
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• 제30권10호
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• pp.942-949
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• 2006

A lumped model is proposed to predict liquid ejection characteristics of a thermally driven inkjet print head. The model is based on a two-dimensional heat conduction equation, an empirical pressure-temperature equation and a nonlinear hydraulic flow-pressure equation. It has been simulated through the construction of an equivalent R-C circuit, and subsequently analyzed using SIMULINK and a circuit simulation tool, PLECS. Using the model, heating and cooling characteristics of the head are predicted to be in agreement with the IR temperature measurements. The effects of the head geometry on the drop ejection are also analyzed using the nonlinear hydraulic model. The present model can be used as a design tool for a better design of thermal inkjet print heads.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.270-275
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• 2010

An electromagnetic pump using a tubular induction motor (TLIM) has been proposed to pump liquid metal fluids. TLIM has been designed for liquid metal flow systems with a motor with a thrust force of 40~77[N]. The flow characteristics have been investigated by solving the Navier-Stokes equation, where the Lorentz force was included simply by considering it as a constant in the Navier-Stokes equation. A wood metal was chosen to simulate the liquid metal. The effect of Lorentz force on the flow rate was investigated. An experiment was conducted and its results were compared with those of the simulation. The simulation result showed an overestimation of about 17% compared with the experimental one.

• 대한전기학회논문지
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• 제38권6호
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• pp.470-476
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• 1989

In order to develop a mathematical model which can predict the operating voltage and current of a discharge lamp, the properties and the physical phenomena of a low pressure gas discharge are investigated. Fluorescent lamp which uses a low pressure mercury-argon gas discharge is used in the model development. In a low pressure mercur-argon gas discharge, the continuity equation for each excited atom and electron, and the electron energy balance equation can predict the physical quantities of discharge. By coupling these equations and the circuit equation, the electrical characteristics of the discharge lamp can be predicted. To verify the validity of the suggested model, we calculated the voltage and current of a fluorescent lamp operating with inductor ballast for source frequency of 5KHz, 8KHz, 10KHz, and 13KHz. The results show good agreements in wave forms between the measured voltage and current, and the difference between the measured and calculated one is less than 5%.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.14-17
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• 2001

In this paper, the vibration characteristics of a 2-phase Hybrid type Linear Stepping Motor(HLSM) are analyzed using the ACSL. A magnetic equivalent circuit is based on the structure of the HLSM, and then the electric equivalent circuit of the HLSM is derived by solving equations for the magnetic equivalent circuit. A normal force is calculated using FEM(Flux2D). And the vibration characteristics of the HLSM are simulated by the ACSL with the voltage equations, the thrust equation, the normal force equation and the kinetic equation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1026-1031
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• 2001

In this paper. the dynamic characteristics of a super high-speed tilting-pad air bearing(TPGB) used in a turbo expander with high expansion ratio are analyzed. The dynamic behavior and stability of a rotary system supported by two journal air bearings are investigated numerically. The transient response of the shaft is obtained by simultaneously solving the equation of motion of the shaft and the dynamic Reynolds equation. The stiffness and damping coefficients of the bearing are calculated from the loading coefficients of the bearing are calculated from the loading capacity. shaft velocity and displacement by using a curve fitting method. The natural frequencies of the 1st and 2nd rigid modes can be calculated from these coefficients. The theoretical method of a rigid rotor system is verified by experimentsut.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.145-153
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• 1997

Dynamic characteristics are investigated when a nonlinear system showing periodic and chaotic responses under harmonic excitation is exposed to random perturbation. About two well potential problem, probability of homoclinic bifurcation is estimated using stochastic generalized Meinikov process and quantitive characteristics are investigated by calculation of Lyapunov exponent. Critical excitaion is calculated by various assumptions about Gaussian Melnikov process. To verify the phenomenon graphically Fokker-Planck equation is solved numerically and the original nonlinear equation is numerically simulated. Numerical solution of Fokker-Planck equation is calculated on Poincare section and noise induced chaos is studied by solving the eigenvalue problem of discretized probability density function.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.38-41
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• 2000

High temperature cure characteristics of polyester resin systems were investigated by isothermal and dynamic differential scanning calorimetries. During isothermal scanning, the experimental procedure was modified to reduce the initial Boss of heat. no kinetic equation from the isothermal experiment was compared with that from the dynamic experiment.

• 대한조선학회논문집
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• 제49권3호
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• pp.227-231
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• 2012

In this study, a plastic hardening constitutive equation for steels of polar class vessels at low temperature is proposed. The equation was derived using the experimental data obtained from tensile tests at room and low temperatures. Tensile tests at low temperature are both costly and time consuming because an expensive cold chamber is necessary and it takes too much time to cool down a specimen to set temperature. Using the proposed plastic hardening constitutive equation the plastic hardening characteristics of steels for polar class vessels at low temperature can be easily predicted from the tensile test results at room temperature.

• 전자공학회논문지D
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• 제34D권8호
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• pp.15-25
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• 1997

The integration method of carier concentrations to redcue the discretization error of th box integratio method used in the discretization of the three-dimensional poisson's equation is presented. The carrier concentration is approximated in the closed form as an exponential function of the linearly varying potential in the element. The presented method is implemented in the three-dimensional poisson's equation solver running under the windows 95. The accuracy and the convergence chaacteristics of the three-dimensional poisson's equation solver are compared with those of DAVINCI for the PN junction diode and the n-MOSFET under the thermal equilibrium and the DC reverse bias. The potential distributions of the simulatied devices from the three-dimensional poisson's equation solver, compared with those of DAVINCI, has a relative error within 2.8%. The average number of iterations needed to obtain the solution of the PN junction diode and the n-MOSFET using the presented method are 11.47 and 11.16 while the those of DAVINCI are 21.73 and 23.0 respectively.