• Title/Summary/Keyword: harmonic-analysis

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The Study on Current Characteristic according to Core Cutting Degree in Three-Phase Induction Motor with Rectangular Stator Core (사각 고정자 철심을 가지는 삼상 유도전동기의 고정자 철심 절단 각에 따른 전류 특성 연구)

  • Im, Jong-Bin;Kim, Seung-Joo;Kim, Kwang-Soo;Lee, Hyung-Woo;Kim, Sol;Lee, Ju
    • Proceedings of the KSR Conference
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    • 2009.05a
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    • pp.1649-1654
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    • 2009
  • Induction motors widely use in industry because structure is simple and hard and cost is generally cheap and they are easy to control. In recently, because of saving steel, ventilation and benefit of frame fixing, rectangular core type induction motors use in industry more and more. This paper presents current characteristic according to stator core cutting degree in three-phase induction motor (IM) with rectangular stator core. According to stator cutting degree, magnetic saturation and paths of flux are changed. Because of these situations, phase currents are unbalance and are produced harmonic components and they cause decrease of efficiency. We analyze each $10^{\circ}$ from $0^{\circ}$ to $30^{\circ}$ using 2-D finite element analysis (FEA). Optimal stator cutting core degree selection supplies stable currents and efficiency improvement. In this paper, loss separation test was executed by IEEE Std. 112-98 Method B and we compare with the result of loss separation by Simulation using FEM and by Experiment.

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Nonlinear Forced Torsional Vibration for the Engine Shafting System With Viscous Damper (점성댐퍼를 갖는 엔진 축계의 비선형 비틀림강제진동)

  • 박용남;송성옥;김의간;전효중
    • Journal of Advanced Marine Engineering and Technology
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    • v.20 no.4
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    • pp.50-58
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    • 1996
  • The torsional vibration of the propulsion shafting system equipped with viscous damper is investigated. The equivalent system is modeled by a two mass softening system with Duffing's oscillator and the vibratory motion is described by non-linear differential equations of second order. The damper casing is fixed at the front-end of crankshaft and the damper's inertia ring floats in viscous silicon fluid inside of the camper casing. The excitation frenquency is proportional to the rotational speed of engine. The steady state response of the equivalent system is analyzed by the computer and for this analyzing, the harmonic balance method is adopted as a non-linear vibration analysis technique. Frequency response curves are obtained for 1st order resonance only. Jump phenomena are explained. The discriminant for the solutions of the steady state response is derived. Both theoretical and measured results of the propulsion shafting system are compared with and evaluated. As a result of comparisions with both data, it was confirmed that Duffing's oscillator can be used in the modeling of the propulsion shafting system attached with viscous damper with non-linear stiffness.

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Nonlinear Forced Torsional Vibration for the Engine Shafting System With Viscous Damper (점성댐퍼를 갖는 엔진 축계의 비선형 비틀림강제진동)

  • Park, Y.N;Song, S.O;Kim, U.K;Jeon, H.J
    • Journal of Advanced Marine Engineering and Technology
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    • v.20 no.4
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    • pp.372-372
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    • 1996
  • The torsional vibration of the propulsion shafting system equipped with viscous damper is investigated. The equivalent system is modeled by a two mass softening system with Duffing's oscillator and the vibratory motion is described by non-linear differential equations of second order. The damper casing is fixed at the front-end of crankshaft and the damper's inertia ring floats in viscous silicon fluid inside of the camper casing. The excitation frenquency is proportional to the rotational speed of engine. The steady state response of the equivalent system is analyzed by the computer and for this analyzing, the harmonic balance method is adopted as a non-linear vibration analysis technique. Frequency response curves are obtained for 1st order resonance only. Jump phenomena are explained. The discriminant for the solutions of the steady state response is derived. Both theoretical and measured results of the propulsion shafting system are compared with and evaluated. As a result of comparisions with both data, it was confirmed that Duffing's oscillator can be used in the modeling of the propulsion shafting system attached with viscous damper with non-linear stiffness.

Fourier Series Expansion Method for Free Vibration Analysis of a Partially Liquid-Filled Circular Cylindrical Shell (Fourier 급수전걔를 이용한 부분적으로 유체가 채워진 원통형 셸의 고유진동 해석)

  • 정경훈;이성철
    • Journal of KSNVE
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    • v.4 no.2
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    • pp.163-175
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    • 1994
  • An analytical method for nautral frequencies of a partially liquid- filled circular cylindrical shell with various boundary conditions is developed by means of the Stokes's transformation and Fourier series expansion on the basis of Sanders' shell equation. The liquid-shell coupled system is divided into two regions for convenient formulation. One is the empty shell region in which the Sanders' shell equations are formulated without the lipuid effect, the other is wetted shell region in which the shell equations are formulated with consideration of the liquid dynamic effect. The shell equations for each regions are combined by the geometry and the force continuities at the junction of the two regions. For the vibration relevant to the liquid motion, the velocity potential of liquid is assumed as a sum of linear combination of suitable harmonic functions in axial direction. The unknown parameters are selected to satisfy the boundary condition along the wetted shell surface. The natural frequencies of the liquid filled cylindraical shells with the clamped- free and the clamped-clamped boundary conditions examined in the previous works, are obtained by this analytical method. The results are compared with the previous works, and excllent agreement is found for the natural frequencies of the shells.

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A Circuit Simulation Model of Ferroelectric Capacitors and its AHDL Implementation (강유전체 캐패시터의 회로 시뮬레이션 모델과 이의AHDL 구현)

  • Kim, Shi-Ho
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.10
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    • pp.25-32
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    • 2000
  • We provided a model for accurately computing the Hysteresis characteristics of the ferrelectric thin film capacitors. This model is developed form the semi-empirical ferroelectric model based on the double well harmonic oscillator. We have seen that this model is consistent with physical analysis using the Preisach's hysteresis distribution. This model includes the parameters representing the slope of changing Hysteresis curves and the imprint of ferroelectric capacitors. Besides, we showed that this model could predict accurate sub-hystersis loop by the turning points when the polarities of applied voltage were changed before saturation. The simulation and measurement result showed that this model is well applicable to both PZT and SBT materials. This model has been described by AHDL and successfully implemented into Spectre simulator to provide circuit design environment of commercial CAD tools such as Cadence software.

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On the Vibration Analysis of the Floating Elastic Body Using the Boundary Integral Method in Combination with Finite Element Method

  • K.T.,Chung
    • Bulletin of the Society of Naval Architects of Korea
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    • v.24 no.4
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    • pp.19-36
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    • 1987
  • In this research the coupling problem between the elastic structure and the fluid, specially the hydroelastic harmonic vibration problem, is studied. In order to couple the domains, i.e., the structural domain and the fluid domain, the boundary integral method(direct boundary integral formulation) is used in the fluid domain in combination with the finite element method for the structure. The boundary integral method has been widely developed to apply it to the hydroelastic vibration problem. The hybrid boundary integral method using eigenfunctions on the radiation boundaries and the boundary integral method using the series form image-functions to replace the even bottom and free surface boundaries in case of high frequencies have been developed and tested. According to the boundary conditions and the frequency ranges the different boundary integral methods with the different idealizations of the fluid boundaries have been studied. Using the same interpolation functions for the pressure distribution and the displacement the two domains have been coupled and using Hamilton principle the solution of the hydroelastic have been obtained through the direct minimizing process. It has become evident that the finite-boundary element method combining with the eigenfunction or the image-function method give good results in comparison with the experimental ones and the other numerical results by the finite element method.

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Construction of Orthogonal Basis Functions with Non-Divergent Barotropic Rossby-Haurwitz Waves

  • Cheong, Hyeong-Bin;Jeong, Hanbyeol;Kim, Wonho
    • Journal of the Korean earth science society
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    • v.35 no.5
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    • pp.333-341
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    • 2014
  • A new set of basis functions was constructed using the Rossby-Haurwitz waves, which are the eigenfunctions of nondivergent barotropic vorticity equations on the sphere. The basis functions were designed to be non-separable, that is, not factored into functions of either the longitude or the latitude. Due to this property, the nodal lines of the functions are aligned neither along with the meridian nor the parallel. The basis functions can be categorized into groups of which members have the same degree or the total wavenumber-like index on the sphere. The orthonormality of the basis functions were found to be close to the machine roundoffs, giving the error of $O(10^{-15})$ or $O(10^{-16})$ for double-precision computation (64 bit arithmetic). It was demonstrated through time-stepping procedure that the basis functions were also the eigenfunctions of the non-divergent barotropic vorticity equations. The projection of the basis functions was carried out onto the low-resolution geopotential field of Gaussian bell, and compared with the theory. The same projections were performed for the observed atmospheric-geopotential height field of 500 hPa surface to demonstrate decomposition into the fields that contain disturbance of certain range of horizontal scales. The usefulness of the new basis functions was thus addressed for application to the eigenmode analysis of the atmospheric motions on the global domain.

A Novel Islanding Detection Scheme without Non Detection Zone (불검출영역이 없는 새로운 단독운전 검출기법)

  • Jo, Yeong-Min;Kim, Dong-Gyun;Cho, Sang-Yoon;Song, Seung-Ho;Choy, Ick;Lee, Young-Kwoun;Choi, Ju-Yeop
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.6
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    • pp.540-549
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    • 2015
  • Unintentional islanding results in safety hazards, reliability, and many other issues. Therefore, the islanding detection of a power conditioning system of a distributed generation, such as a grid-connected photovoltaic inverter, is a key function for standard compliance. Currently, many anti-islanding schemes have been examined, but existing anti-islanding schemes have poor power quality and non-detection zone issues. Therefore, this study analyzes the non-detection zone in a more deliberate manner than the existing analysis of the non-detection zone and proposes a new anti-islanding scheme, which has negligible power quality degradation and no non-detection zone. Simulation and experimental results validate that the proposed scheme shows much better performance than other existing schemes.

An MMIC VCO Design and Fabrication for PCS Applications

  • Kim, Young-Gi;Park, Jin-Ho
    • Journal of Electrical Engineering and information Science
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    • v.2 no.6
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    • pp.202-207
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    • 1997
  • Design and fabrication issues for an L-band GaAs Monolithic Microwave Integrated Circuit(MMIC) Voltage Controlled Oscillator(VCO) as a component of Personal Communications Systems(PCS) Radio Frequency(RF) transceiver are discussed. An ion-implanted GaAs MESFET tailored toward low current and low noise with 0.5mm gate length and 300mm gate width has been used as an active device, while an FET with the drain shorted to the source has been used as the voltage variable capacitor. The principal design was based on a self-biased FET with capacitive feedback. A tuning range of 140MHz and 58MHz has been obtained by 3V change for a 600mm and a 300mm devices, respectively. The oscillator output power was 6.5dBm wth 14mA DC current supply at 3.6V. The phase noise without any buffer or PLL was 93dB/1Hz at 100KHz offset. Harmonic balance analysis was used for the non-linear simulation after a linear simulation. All layout induced parasitics were incorporated into the simulation with EEFET2 non-linear FET model. The fabricated circuits were measured using a coplanar-type probe for bare chips and test jigs with ceramic packages.

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Analysis of Response behaviors of offshore mooring structures by a piecewise-linear system (구분적선형시스템을 이용한 해양 구조물의 거동분석)

  • 마호성
    • Computational Structural Engineering
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    • v.10 no.4
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    • pp.251-265
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    • 1997
  • A piecewise-linear system is utilized to model the offshore mooring system. The approximated piecewise-linear restoring force is obtained to be compared with the analytically derived restoring force of a mooring system. Two systems are compared to verify the applicability of the piecewise-linear system to evaluate responses of the mooring system. Using the piecewise-linear system, the response behaviors of mooring systems are examined under various excitations. Nonlinearity of the system and effects of both system and excitation parameters are intensively examined. System responses are identified mainly by observing Poincare maps. The mooring system is found to have various types of responses such as regular harmonic, subharmonic and complex nonlinear behaviors, including chaos by utilizing a piecewise-linear system. Various values of parameters are applied to determine the effects of parameters upon system responses. Response domains are determined by establishing parametric maps.

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