• Title/Summary/Keyword: Equivalent transformation

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Eigenvalue Analysis of Symmetrically Stepped Beams by Equivalent Beam Transformation (대칭단헝 단순보의 등가보 변환에 의한 고유치 해석)

  • Jung Jae-Chul;Moon Sang-Pil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.1 s.71
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    • pp.55-62
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    • 2006
  • The natural frequency of a beam plays a critical role in the dynamic analysis of beams. Especially it is a complicated and difficult task to analyse the natural frequency of a stepped beam with an irregularly varying section. The lumped mass methods, multi-degree of freedom analyses, are mainly used for the analysis of this kind of stepped beams. The accuracy of these methods are determined by the number of the partitions of elements, the number of the iterations in calculation, and the accuracy of assumed mode shapes. This study presents a method of transformation from symmetrically stepped beams to an equivalent beam and a method of the eigenvalue analysis. Appropriateness and utility of this method are demonstrated by comparing examples from other literatures and various models.

REGULAR RELATION WITH RESPECT TO A HOMOMORPHISM

  • Yu, Jung Ok;Lee, Young Chan
    • Journal of the Chungcheong Mathematical Society
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    • v.11 no.1
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    • pp.59-71
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    • 1998
  • In this paper we define a regular relation with respect to a homomorphism in transformation groups and we find the equivalent conditions for the relation to be an equivalence relation.

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Comparison of Energy Demand in Multi-Story Structures and Equivalent SDOF Systems (다층 구조물과 등가 단자유도계의 에너지 요구량 비교)

  • 최현훈;원영섭;김진구
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.19-26
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    • 2003
  • In energy-based design, the structures are generally transformed into equivalent SDOF systems to obtain the input and the dissipated energy. In this study the energy demands in multi-story structures were compared with that of equivalent single degree of freedom systems to validate the transformation method. Three-, eight-, and twenty-story steel moment-resisting frames and buckling restrained braced frames are compared with those of equivalent single degree of freedom systems. Sixty earthquake ground motions recorded in different soil conditions were used to compute the input and hysteretic energy demands in model structures. According to the analysis results, in 3 and 8-story structures the hysteretic energy demands computed in the equivalent SDOF structures are compatible with those computed in the original MDOF structures, while in the 20-story structures the transformed equivalent structures underestimated the hysteretic energy demands.

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An Experimental Study of Reconstruction from Laser Diffraction Measurement for Axisymmetric Sprays (레이저 회절법을 이용한 축대칭 분무 구조의 공간 분포 변환에 관한 실험적 연구)

  • 양승연;이충훈;구자예;정석호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.1
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    • pp.10-16
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    • 2000
  • Spatially resolved liquid volume fractions from a set of line-of-sight laser diffraction measurements for axisymmetric sprays generated from a pintle-type gasoline injector have been tomographically reconstructed by Abel transformation, Fourier transformation and onion peeling method. Spatially resolved liquid volume fractions classified into 32 size groups were translated characteristics of SI engine fuel sprays. These data were also obtained from the phase Doppler measurements for the same sprays. The comparison between laser deffraction measurements and transformation reconstructs more reasonable spatially resolved characteristics for axisymmetric sprays as well as for asymmetric sprays.

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The Eddy Current Method to Measure the Transformation Ratio in Metals (와전류 시험에 의한 금속의 변태율 측정에 관한 연구)

  • Wee, Sang-Bong;Han, Min-Koo;Paek, KI-Nam
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.38 no.5
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    • pp.348-354
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    • 1989
  • The metallurgical transformation ratios of metals have been evaluated by the eddy current method. Eddy current probes have been designed and applied to various standard samples. The equivalent impedance estimated from the eddy current measurement is closely related to the variation of transformation ratios in metals. It has been found that the variation of the impedance is relatively large in the samples where the transformation ratios of the samples are small. Both reactance and resistance increase when the transformation ratio is large. Sensitivities of eddy current test is increased with increasing frequencies and by inserting ferrite core the solenoid eddy probe. Our results have shown the implementation of eddy current measurement to the one-line nondestructive testing of metals.

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Equivalent Circuit Model for Four Port Connector System (4포트 커넥터 시스템의 등가회로 변환에 관한 연구)

  • Shim, Min-Kyu;Kim, Jong-Min;Nah, Wan-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.6
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    • pp.1105-1110
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    • 2007
  • This paper describes an equivalent circuit modeling of 4-port connector system. A coupled transmission line was designed and fabricated, mimicking a 4-port connector system, and then S-parameters were measured using 4 port VNA (Vector Network Analyzer). The S-parameters from measurement and from Full-wave simulator coincided quite nice. By using these S parameters, an equivalent circuit parameters for a 4-port system was obtained. The time domain response from the equivalent circuit model matched to the signals, which was measured using TDR(Time Domain Reflectometry) meter. We were also convinced that there should be enough bandwidth to get a meaningful time domain result from Fourier inverse transformation of the S parameters. In addition, we applied the conversion algorithm to the 4-port connector system, which calculates the S-parameters of a 4 port system using the data from a 2-port VNA with the other ports open. Comparison of the two data, one from measurement and the other one from the conversion algorithm, was made in this manuscript.

Transformation of Dynamic Loads into Equivalent Static Loads by the Selection Scheme of Primary Degrees of Freedom (주자유도 선정 기법에 의한 동하중의 등가 정하중으로의 변환)

  • Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1316-1321
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    • 2003
  • The systematic method to construct equivalent static load from the given dynamic load is proposed in the present study. Previously reported works to construct equivalent static load were based on ad hoc methods. They may results in unreliable structural design. The present study proposes a selection scheme of degrees of freedom(d.o.f) for imposing the equivalent static loads. The d.o.fs are selected by Two-level condensation scheme(TLCS). TLCS consists of two two-steps. The first step is the energy estimation in element-level and the second step consists of the traditional sequential elimination precudure. Through several numerical examples, the efficiency and reliability of proposed scheme is verified.

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Analysis of distributed MMF on tooth for induction motor using Magnetic Equivalent Circuit (자기등가회로법에 의한 유도전동기의 치기자력 분포해석)

  • Jeong, Jong-Ho;Lee, Eun-Woong;Lim, Su-Saeng;Kim, Jun-Ho
    • Proceedings of the KIEE Conference
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    • 2001.07b
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    • pp.638-640
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    • 2001
  • In this paper, system equation of the magnetic equivalent circuit of the induction motor be consist of the magnetomotive force transformation matrix and the flux transformation matrix. The system equation is fed by three phase sinusoidal current and get to magnetomotive force on the teeth. This study confirmed the time and spatial distribution of the magnetomotive force on the teeth created by the winding.

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A Study on the SDINS's Gyro Bias Calibration Method in Disturbances (외란을 고려한 스트랩다운 관성항법장치 자이로 바이어스 교정기법)

  • Lee, Youn-Seon;Lee, Sang-Jeong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.3
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    • pp.368-377
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    • 2009
  • In this paper we study the gyro bias calibration method of SDINS(Strap-Down Inertial Navigation System). Generally, SDINS's calibration is performed in 2-axis(or 3-axis) rate table with chamber for varying ambient temperature. We assumed that the majority of calibration-parameter except for gyro bias is knowned. During gyrobias calibration procedure, it can be induced some disturbances(accelerometer's short-term error induced rate table rotation and anti-vibration mount's rotation). In these cases, old gyro-bias calibration methods(using velocity error or attitude error) have an error, because these disturbances are not detectable at the same time. So that, we propose a new gyro-bias calibration method(heading error minimizing using equivalent linear transformation) that can detect anti-vibration mount's rotation. And we confirm efficiency of the new gyro-bias calibration method by simulation.