• Title/Summary/Keyword: Transfer Matrix method

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Symbolic computation and differential quadrature method - A boon to engineering analysis

  • Rajasekaran, S.
    • Structural Engineering and Mechanics
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    • v.27 no.6
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    • pp.713-739
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    • 2007
  • Nowadays computers can perform symbolic computations in addition to mere number crunching operations for which they were originally designed. Symbolic computation opens up exciting possibilities in Structural Mechanics and engineering. Classical areas have been increasingly neglected due to the advent of computers as well as general purpose finite element software. But now, classical analysis has reemerged as an attractive computer option due to the capabilities of symbolic computation. The repetitive cycles of simultaneous - equation sets required by the finite element technique can be eliminated by solving a single set in symbolic form, thus generating a truly closed-form solution. This consequently saves in data preparation, storage and execution time. The power of Symbolic computation is demonstrated by six examples by applying symbolic computation 1) to solve coupled shear wall 2) to generate beam element matrices 3) to find the natural frequency of a shear frame using transfer matrix method 4) to find the stresses of a plate subjected to in-plane loading using Levy's approach 5) to draw the influence surface for deflection of an isotropic plate simply supported on all sides 6) to get dynamic equilibrium equations from Lagrange equation. This paper also presents yet another computationally efficient and accurate numerical method which is based on the concept of derivative of a function expressed as a weighted linear sum of the function values at all the mesh points. Again this method is applied to solve the problems of 1) coupled shear wall 2) lateral buckling of thin-walled beams due to moment gradient 3) buckling of a column and 4) static and buckling analysis of circular plates of uniform or non-uniform thickness. The numerical results obtained are compared with those available in existing literature in order to verify their accuracy.

Study on Controller Design of AC Servo Permanent Magnet Synchronous Motor by Matrix Converter : Speed Controller (매트릭스 컨버터에 의한 AC 서보 영구자석형 동기전동기의 제어기 설계에 대한 고찰 : 속도제어기)

  • Jeong, Chung-Il;Lee, Sang-Cheol;Mo, Dong-Yeong;Choi, Chang-Young;Kim, Tae-Woong;Park, Gwi-Geun
    • Proceedings of the KIPE Conference
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    • 2008.06a
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    • pp.106-108
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    • 2008
  • This paper deals with the design for speed controller to drive PMSM by matrix converter without DC-link circuit as the power conversion system of AC servo motor drive. To design the speed controller of PMSM drive, the closed-loop transfer function of speed controller is calculated and then the frequency-domain response characteristics are analyzed by bode plot using Matlab. Based on the results by bode plot, the speed control gains are determined. As the real effects of controller designed in the frequency-domain display in the time-domain, the performance of speed controller is confirmed by the step response of speed controller. The design examples are shown and its validity of the design method mentioned in the paper is verified through PSIM simulation.

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Power Factor Compensation for Wideband Acoustic Projector Using Measurement Data and ABCD matrix (ABCD 전송 파라메터를 사용한 광대역 음향 발신기의 역률 개선 연구)

  • Lim, Jun-Seok;Pyeon, Yong-Guk
    • 전자공학회논문지 IE
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    • v.48 no.3
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    • pp.10-15
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    • 2011
  • In the case of designing an acoustic transducer for high power application, we usually aim to transfer the source electric energy to the output acoustic energy as large as possible. For this purpose, we should match the impedance of the power amplifier to the impedance combined with the acoustic transducer impedance and the radiation impedance. Especially if we have electrical source with almost zero impedance, we need improve the power factor of the acoustic transducer in the load. In this paper, we propose a broad band impedance matching method by the improvement of power factor, which applies ABCD matrix.

An Extraction and Analysis of Problem Areas for BTL Projects from the Practical Perspective (실무적 관점에서의 BTL사업 문제영역 도출 및 분석)

  • Kim, Soo-Yong;Son, Myung-Chan;Yang, Jin-Kook
    • Korean Journal of Construction Engineering and Management
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    • v.14 no.3
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    • pp.157-166
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    • 2013
  • Unlike conventional BTO(Build-Transfer-Operate) projects, this BTL project aims at fixing the financial deficiencies of the government and expanding infrastructure through private capital. It allows the government to attract private capital for the construction of public facilities such as schools and social welfare agencies for whom private users don't need to pay, thereby bolstering national finance. BTL projects are causing a variety problems in progress. Therefore, we are required a practical approach to can improving a variety problems. In this study, we were derive the problem areas as follow. First, research data on the problem of domestic BTL projects, Second, high-performing foreign data analysis than domestic. And, we were analyzed to systematic management method for problem areas by using affinity techniques, matrix comparison analysis, AHP technique. Results of this study are expected provide management standards through real problem areas and the analyzing of relatively importance.

Identification of impact forces on composite structures using an inverse approach

  • Hu, Ning;Matsumoto, Satoshi;Nishi, Ryu;Fukunaga, Hisao
    • Structural Engineering and Mechanics
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    • v.27 no.4
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    • pp.409-424
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    • 2007
  • In this paper, an identification method of impact force is proposed for composite structures. In this method, the relation between force histories and strain responses is first formulated. The transfer matrix, which relates the strain responses of sensors and impact force information, is constructed from the finite element method (FEM). Based on this relation, an optimization model to minimize the difference between the measured strain responses and numerically evaluated strain responses is built up to obtain the impact force history. The identification of force history is performed by a modified least-squares method that imposes the penalty on the first-order derivative of the force history. Moreover, from the relation of strain responses and force history, an error vector indicating the force location is defined and used for the force location identification. The above theory has also been extended into the cases when using acceleration information instead of strain information. The validity of the present method has been verified through two experimental examples. The obtained results demonstrate that the present approach works very well, even when the internal damages in composites happen due to impact events. Moreover, this method can be used for the real-time health monitoring of composite structures.

Experimental Evaluation of Direct Measurement for Excitation Forces Acting on the Hard-points of Suspension System to Predict Road-noise Performance (로드노이즈 성능 예측을 위한 현가장치 하드포인트의 가진력 직접 측정법에 대한 실험적 평가)

  • Kang, Yeon June;Kim, Heesoo;Song, David P.;Ih, Kang-Duck;Kim, HyoungGun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.3
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    • pp.184-190
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    • 2015
  • NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

Study on the Resolution Characteristics by Using Magnetic Resonance Imaging 3.0T (3.0T 자기공명영상을 이용한 해상력 특성에 대한 연구)

  • Min, Jung-Whan;Jeong, Hoi-Woun;Han, Ji-Hyun;Lee, Si-Nae;Han, Song-Yi;Kim, Ki-Won;Kim, Hyun-Soo;Son, Jin-Hyun
    • Journal of radiological science and technology
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    • v.43 no.4
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    • pp.251-257
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    • 2020
  • This study was purpose to quantitative evaluation of edge method of modulation transfer function(MTF) and physical image characteristics of by obtain the optimal edge image by using magnetic resonance imaging(MRI). The MRI equipment was used (MAGNETOM Vida 3.0T MRI, Siemense healthcare system, Germany) and the head/neck matrix shim MR coil were 20 channels(elements) receive coil. The MTF results of showed the best value of 0.294 based on the T2 Nyquist frequency of 1.0 mm-1. The MTF results of showed that the T1 image is 0.160, the T1 CE image is 0.250, T1 Conca2 image is 0.043, and the T1 CE (Concatenation) Conca2 image is 0.190. The T2 image highest quantitatively value for MTF. The physical image characteristics of this study were to that can be used efficiently of the MRI and to present the quantitative evaluation method and physical image characteristics of 3.0T MRI.

Study on the Physical Imaging Characteristics by Using Magnetic Resonance Imaging 1.5T (1.5T 자기공명영상을 이용한 물리적 영상 특성에 대한 연구)

  • Min, Jung-Whan;Jeong, Hoi-Woun;Han, Ji-Hyun;Lee, Si-Nae;Park, Jang-Ho;Kim, Ki-Won;Kim, Hyun-Soo
    • Journal of radiological science and technology
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    • v.42 no.5
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    • pp.329-334
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    • 2019
  • This study was purpose to quantitative evaluation of noise power spectrum(NPS) and studied the quantitative evaluation and characteristics of modulation transfer function(MTF) by obtain the optimal edge image by using Coil in magnetic resonance imaging(MRI) equipment through Fujita theory using edge method. The MRI equipment was used (Tim AVANTO 1.5T, Siemense healthcare system, Germany) and the head matrix coil were 12channels(elements) receive coil. The NPS results of showed the best value of 0.004 based on the T2 Nyquist frequency of $1.0mm^{-1}$, and the MTF results of showed that the T1 and T2 values were generally better than the T1 CE and T1 CE FC values. The characteristics of this study were to explain the characteristic method of image quality evaluation in general. To present the quantitative evaluation process and results in the evaluation of MRI image characteristics in radiology.

Calculation of Transverse Vibration of Ship`s Propulsion Shaftings by the Finite Element Method (有限要素法에 의한 推進軸系의 광振動計算에 관한 硏究)

  • Jeon, Hio-Jung;Kim, Hi-Cheol
    • Journal of Advanced Marine Engineering and Technology
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    • v.3 no.1
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    • pp.2-18
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    • 1979
  • Due to increasing ship dimensions and installed propulsive power, resonance frequencies of the propeller shaft system tend to decrease and they can appear in some cases within the operating range of the shaft revolution. For calculation of transverse shaft vibrations, various methods have been proposed but as they are mainly for approximate calculation, no contented results are obtained. For fairly accurate estimation of resonance frequencies in the design stage, one can use transfer matrix method of the finite element method and former is rather prefered in ordinary cases. In this study, the finite element method which is utilized for calculation of the propulsion shaft alignment, is introduced to derive the vibration equation of the ship's propulsion shaftings. The digital computer program is developed to solve the above equation, and the details of preparing the input data are described. The method presented in the underlying report was applied to the shafting of ship which has a lignumvitae bearing to verify its reliability and the results of calculation and those of the measurements on rotating shaft show a good agreement. Calculating methods of exciting of forces and damping forces are also discussed for future work.

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Contribution analysis of underwater radiation noise source using partial coherence function (부분상관 함수를 이용한 수중방사소음 소음원 기여도 분석)

  • Kim, Tae Hyeong;Choi, Jae Yong;Oh, Jun Seok;Kim, Seong Yong
    • The Journal of the Acoustical Society of Korea
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    • v.35 no.2
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    • pp.118-124
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    • 2016
  • In this paper, contribution analysis method using a partial coherence function is dealt with in the case of underwater radiation noise. When performing the contribution analysis using a partial coherence function, it is important to select the order of system input. But in the case of frequency correlated systems, it is very difficult to properly select the order of system input. In order to solve this problem, the contribution analysis is performed by subdividing the area of contribution using multiple coherence function. And the new contribution analysis method is presented by using the relationship between the contribution characteristic matrix and multiple coherence function. In order to validate the new method, calculation is performed about multi-input / single-output model which is composed of sine waves. The result of calculation shows that it is possible to derive the exact contribution values.