• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.67-69
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• 1999

This study deals with the unbalance response of a rotor of Switched Reluctance Motor(SRM) due to unbalanced mass. The method to analyze SRM with rotor-bearing system is based on an extension of the well-known Transfer Matrix Method(TMM). Most of the calculation results present the natural frequencies as a function of the speed of rotation which yields critical speeds and response to unbalanced mass.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.386-391
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• 2001

In this paper, the vibration characteristics of IHTS(Intermediate Heat Transfer System) piping system of LMR(Liquid Metal Reactor) conveying hot liquid sodium are investigated to eliminate the pipe supports for economic reasons. To do this, a 3-dimensional straight pipe element and a curved pipe element conveying fluid are formulated using the dynamic stiffness method of the wave approach and coded to be applied to any complex piping system. Using this method, the dynamic characteristics including the natural frequency, the frequency response functions, and the dynamic instability due to the pipe internal flow velocity are analyzed. As one of the design parameters, the vibration energy flow is also analyzed to investigate the disturbance transmission paths for the resonant excitation and the non-resonant excitations.

• 전자공학회논문지S
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• 제35S권5호
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• pp.103-110
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• 1998

In this paper we propose various rotation block realization method of MIMO LBR system. For this, we first discuss how to realize a given LBR system in the form of LBR two-pair cascades. Then we examine several systematic extraction procedures which enable to realize each LBR two-pair in the form of rotation block. Then we consider which realization methods we select for each two-pair block in view of the dynamci range of the coefficients of the rotation blocks. Finally, we demonstrate the LBR realization method using a detailed numerical example that converts a 4th order IIR filter function into a 4*4 transform domain transfer matrix, and then realizes it in a rotation-block cascade.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.91-92
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• 2007

본 연구에서는 전력계통에서 발생되는 surge나 고장전류에 의해서 변압기의 고압측 코일에 유도되는 전자력의 크기를 유한요소 전자계해석 프로그램(FLUX2D)의 축대칭FEM을 이용하여 해석하였다. 1MVA, 22900/220(V) 단상 외철형 Cable형 변압기의 권선의 각방향의 전자력을 분석하고, 변압기 권선의 고유진동mode를 Transfer Matrix Method를 이용하여 Cable형권선의 고유진동주파수를 파악하고 ANSYS와 비교하였다. 변압기 권선의 전자력과 진동mode 분석결과는 변압기의 절연설계 및 단락기계력에 대한 프레임 구조 설계를 위한 자료로 활용될 수 있다.

• 한국정밀공학회지
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• 제21권9호
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• pp.103-110
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• 2004

Pressure ripples yield noise and vibration in hydraulic pipelines, which are inevitably generated by a fluctuation of flow rate in the pump mechanism, and such noise and vibration deteriorate the stability and accuracy of hydraulic systems. To reduce the pressure ripples, accumulator and hydraulic attenuator are normally used. In this study, parallel pipeline with a bent-axis piston pump is introduced to a hydraulic pipe system as a method for reducing the pressure ripples and using the transfer matrix method, the dynamic characteristics of the pipe system are analysed and compared with experimental results. The results show that the phase interference using parallel pipeline with a bent-axis piston pump is effective to reduce the pressure ripples in the hydraulic pipelines.

• 제어로봇시스템학회논문지
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• 제11권2호
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• pp.93-102
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• 2005

The Nyquist robust stability margin is proposed as a measure of robust stability for systems with Affine TFM(Transfer Function Matrix) parametric uncertainty. The parametric uncertainty is modeled through a Affine TFM MIMO (Multi-Input Multi-Output) description with dead-time, and the unstructured uncertainty through a bounded perturbation of Affine polynomials. Gershgorin's theorem and concepts of diagonal dominance and GB(Gershgorin Bands) are extended to include model uncertainty. Multiloop PI/PID controllers can be tuned by using a modified version of the Ziegler-Nichols (ZN) relations. Consequently, this paper provides sufficient conditions for the robustness of Affine TFM MIMO uncertain systems with dead-time based on Rosenbrock's DNA. Simulation examples show the performance and efficiency of the proposed multiloop design method for Affine uncertain systems with dead-time.

• 대한조선학회논문집
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• 제31권2호
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• pp.29-37
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• 1994

본 논문에서는 선박 추진축계의 정확한 임계속도 추정을 위한 모델링방법 및 해석방법을 제시하였다. 해석방법으로서는 전달행렬법을 사용하여 추진축의 임계속도 및 선회운동응답을 구하였다. 또한, Jasper식과 Panagopulos식 등과 같은 간이 추정식들의 타당성을 검증하기 위하여 수치계산을 수행하였다. 일반적인 선박 추진축계에 대한 수치계산 결과로부터 축의 임계속도는 저어널베어링의 위치 및 지지조건에 민감함을 알 수 있었다.

• 대한기계학회논문집A
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• 제25권1호
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• pp.153-160
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• 2001

A general procedure for the design sensitivity analysis of structural dynamic problems has been presented in frame of the FRF-based substructuring formulation. For a system response function, the proposed method gives a parametric design sensitivity formula in terms of the partial derivatives of the connection element properties and the transfer matrix of the subsystems. The derived design sensitivity formula is applied to an engine mount system. An interior noise problem in the passenger car is analyzed using the FRF-based substructuring method and the proposed formulation is adopted to study the response variations with respect to the dynamic characteristics of the engine mounts and the bushes. To obtain the FRFs, a finite element model is built for the engine mount structures, and test data is used for the trimmed body including cabin cavity. The comparison of sensitivities derived by the proposed method and the finite difference method shows that the proposed method is efficient and accurate. The proposed sensitivity analysis method indicates effectively the most sensitive location to the interior noise among the engine mounts and the bushes.

• Earthquakes and Structures
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• 제9권1호
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• pp.173-194
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• 2015

Site response analysis is an important topic in earthquake engineering. A time-domain numerical method called as one-dimensional (1D) finite element artificial boundary method is proposed to simulate the homogeneous plane elastic wave propagation in a layered half space subjected to the obliquely incident plane body wave. In this method, an exact artificial boundary condition combining the absorbing boundary condition with the inputting boundary condition is developed to model the wave absorption and input effects of the truncated half space under layer system. The spatially two-dimensional (2D) problem consisting of the layer system with the artificial boundary condition is transformed equivalently into a 1D one along the vertical direction according to Snell's law. The resulting 1D problem is solved by the finite element method with a new explicit time integration algorithm. The 1D finite element artificial boundary method is verified by analyzing two engineering sites in time domain and by comparing with the frequency-domain transfer matrix method with fast Fourier transform.

• 한국통신학회논문지
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• 제21권7호
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• pp.1850-1860
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• 1996

We present the results for the design ofantireflection (AR) coatings on facets of a multilayered structure waveguide device. The method, whose results agree very well with the reusults of the rigorous method in the case of a symmetric three layer structure deveice, is extended for the design of AR coatings on the facets of a multilayered structure waveguide device. the field profile in a multilayered structure waveguide necessary for the use of the extended method is obtained from the transfer matrix method. The virtual four layered structure method (VFLM) is proposed to reduce the time for the design ofAR coatings because the time for the design of AR coatings using the extended method increases as the number of layers increases. The optimum coating parameters and tolerance mapsfor two different six layered waveguide devices in Ref. [9] and [10] are obtained using the extendedmethod and the VFLM,and for the three different cases approximated as three layered waveguide devices to compare the results of each case. The results of the VFLM are similar to those of the extended methodcompared to those of the three layered structure waveguide. The main reason for the above results is that the field profile in the device calculated usingthe VFLM is similar to that calculated using the extended method compared to that for three layered structure wavegjide. We conclude that the extended method or VFLM should be used for the design of AR coatings on facets of a deice required for the facet reflectivity less than 10$^{-3}$ such as a semiconductor otical amplifier.