• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.620-624
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• 2004

Th is paper presents a systematical approach to study carrier based PWM techniques (CPWM) in diode-clamped and cascade multilevel inverters by using the proposed multi-modulating pattern method. This method is based on the vector correlation between CPWM and space vector PWM (SVPWM) and applicable to both multilevel inverter topologies. The CPWM technique can be described in a general mathematical equation, and obtain the same outputs similarly as of corresponding SVPWM. Control of the fundamental voltage, vector redundancies and phase redundancies in multilevel inverter can be formulated separately in the CPWM equation. The deduced CPWM can obtain a full vector redundancy control, and fully utilize phase redundancy in a cascade inverter. In the paper, CPWM equations and corresponding algorithm for generating multi-modulating signals will be performed, in which SVPWM attributes will be presented by corresponding controllable factors.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.625-629
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• 2004

This paper presents a systematical approach to study carrier based PWM techniques (CPWM) in diode-clamped and cascade multilevel inverters by using a proposed named multi-modulating pattern method. This method is based on the vector correlation between CPWM and the space vector PWM (SVPWM) and applicable to both multilevel inverter topologies. A CPWM technique can be described in a general mathematical equation, and obtain the same outputs similarly as of the corresponding SVPWM. Control of the fundamental voltage, vector redundancies and phase redundancies in multilevel inverter can be formulated separately in the CPWM equation. The deduced CPWM can obtain the full vector redundancy control, and fully utilize phase redundancy in a cascade inverter In this continued part, it will be deduced correlation between CPWM equations in multi-carrier system and single carrier system, present the mathematical model of voltage source inverter related to the common mode voltage and propose a general algorithm for multi-modulating modulator. The obtained theory will be demonstrated by simulation results.

• 한국통신학회논문지
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• 제21권11호
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• pp.3012-3023
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• 1996

In this paper, we analyze the compression of optical soliton which is obtained by proceeding the optical pulse in FSDD(Fiber with Slowly Decreasing Dispersion) using both NSE(Nonlinear Schrodinger Equation) and GNSE(General Nonlinear Schrodinger Equation) and compare the results. We replace the FSDD with a sequence of fibers having different dispersion values and pompre the results with those obtained in FSDD. It is found that the same results in peak value and FWHM(Full width Half Maximum) can be obtained by replacing FSDD with a sequence of fibers having proper length. We vary the shape of initial pulse which is the input of FSDD and suggest the condition to obtain higher compression rate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.15-19
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• 1989

In this paper, the thrust force characteristic of SLIM according to the variation of several parameters was calculated from the fundamental equation based on Maxwell' s electromagnetic equation to design the transportation system which is drived by short primary single sided linear induction motor. The transportation system of moving secondary was constructed by the design values calculated on the base of simulated data and this values were compared to experimental values, and also the control method of transportation system was proposed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.539-542
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• 1997

We present a micro-positioning stage that has minimized geometrical error and can drive in the 4-axis. This stage divided into two parts: $Z\theta_x$ $\theta_y$, motion stage and$\theta_z$ motion stage. These stages are constructed in flexure hinges, piezoelectric actuators and displacement scnsors. The dynamic model for each stage is obtained and their FE (finite element) models are made. Using the Lagrange's equation, the motion of equation is found. Through the parametric analysis and FE analysis, sensitiv~ty of the design parameters is executed. Finally, fundamental frequencies, maximum stress, and displacement sensitivity for each stage are obtained. We expect that this micro-positioning stage be a useful micro-alignment device for various applications.

• 한국소음진동공학회논문집
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• 제15권10호
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• pp.1195-1201
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• 2005

In this paper, the effect of a moving mass on dynamic behavior of the cracked cantilever beam on elastic foundations is presented. Based on the Euler-Bernoulli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. That is, the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory The crack is assumed to be in the first mode of fracture. As the depth of crack is increased, the tip displacement of the cantilever beam is Increased. When the depth of crack is constant, the frequency of a cracked beam is proportional to the spring stiffness.

• Structural Engineering and Mechanics
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• 제29권6호
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• pp.673-687
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• 2008

In this paper, a thermo-viscoelastic problem in an infinite isotropic medium in two dimensions in the presence of a point heat source is considered. The fundamental equations of the problems of generalized thermoelasticity including heat sources in a thermo-viscoelastic media have been derived in the form of a vector matrix differential equation in the Laplace-Fourier transform domain for a two dimensional problem. These equations have been solved by the eigenvalue approach. The results have been compared to those available in the existing literature. The graphs have been drawn for different cases.

• 한국소음진동공학회논문집
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• 제15권4호
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• pp.483-491
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• 2005

In this paper a dynamic behavior of a double-cracked cantilever pipe with the tip mass and a moving mass is presented. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Lagrange's equation. The influences of the moving mass, the tip mass and double cracks have been studied on the dynamic behavior of a cantilever pipe system by numerical method. The cracks section are represented by the local flexibility matrix connecting two undamaged beam segments. Therefore, the cracks are modelled as a rotational spring. This matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. We investigated about the effect of the two cracks and a tip mass on the dynamic behavior of a cantilever pipe with a moving mass.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.799-804
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• 2004

In this paper a dynamic behavior of simply supported cracked simply supported beam with the moving masses is presented. Based on the Timoshenko beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics the of. And the crack is assumed to be in th first mode of fracture. As the depth of the crack and velocity of fluid are increased the mid-span deflection of the pipe conveying fluid with the moving mass is increased. As depth of the crack is increased, the effect that the velocity of the fluid on the mid-span deflection appeals more greatly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.712-717
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• 2000

The main purpose of this paper is to present both the fundamental and some higher natural frequencies of axially loaded Timoshenko beams resting on the elastic foundation. The non-dimensional differential equation governing the free vibrations of such beam is derived in which the effects of rotatory inertia and shear deformation are included. The Improved Euler method and Determinant Search method are used to perform the integration of the differential equation and to determine the natural frequencies, respectively. The hinged-hinged, hinged-clamped and clamped-clamped end constraints are applied in numerical examples. The relations between frequency parameters and both the foundation parameter and slenderness ratio are presented in figures. The effect of cross-sectional shapes is also investigated.