• 한국기계가공학회지
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• 제9권3호
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• pp.35-41
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• 2010

In this study, a mode analysis of uncoupled system was discussed using FRF. The eigen-mode range of FRF analysis is consistent with conventional FFT in spectrum. Also, the numerical response of second order uncoupled system was obtained using the Runge-Kutta Gill method. The displacement, velocity and acceleration response were calculated after numerical analysis and its response was used for the calculation of FRF for uncoupled system. Using the separated and mixed response of 1st and 2nd mode in example, its FRF was analysed for the prediction of the uncoupled systems and its mode shape was calculated by solving the eigen problem.

• 소음진동
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• 제10권5호
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• pp.800-805
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• 2000

To determine the modal matrix and modal frequency of engine mount system, we most solve so-called eigen-value problem. However eigen-value problem of engine mount system with hydraulic mount can not be solved by general eigne-analysis algorithm because the properties of hydraulic mount vary with frequency. so in this paper the method for modal analysis of rigid body motions of an engine supported by hydraulic mount is proposed. Natural frequencies and mode shapes of this nonlinear system are obtained by using complex exponential method and Laplace transformation method. In time domain, impulse response functions are calculated by (two-sided) discrete inverse Fourier Transformation of forced frequency response functions achieved by Laplace transformation of the differential equation of motion. Considering the fact that frequency response functions synthesized by modal parameters form proposed method are in good agreement with original FRFs, it is proved that the proposed method is very efficient and useful for the analysis of eigne-value problem of hydraulic engine mount system.

• Steel and Composite Structures
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• 제46권6호
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• pp.719-729
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• 2023

This paper studies electro-magneto-mechanical bending studying of the cylindrical panels based on shear deformation theory. The cylindrical panel is constrained with two simply-supported edges at longitudinal direction and two clamped boundary conditions at circumferential direction. The governing equations are derived based on the principle of virtual work in cylindrical coordinate system. Levy-type solution of the governing equations is derived to reduce two dimensional PDEs to a 2D ODEs. The reduced ordinary differential equation is solved using the Eigen-value Eigen-vector method for the clamped-clamped boundary condition. The electro-magneto-mechanical bending results are obtained to show that every displacement, rotation and electromagnetic potentials how change with changes of initial electromagnetic potentials and mechanical loads along longitudinal and circumferential directions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.33-36
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• 2001

We introduce, in this paper, the face recognition method that improves recognition rate and training time in eigen system. To increase recognition rate we use Gabor filter. To reduce the increasing training time owing to use Gabor filtering, we extract new feature vectors that are made with average and standard deviation. In experimental results, we get higher recognition rate and shorter training time in improved system than it in original eigen system.

• Journal of electromagnetic engineering and science
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• 제4권4호
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• pp.183-189
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• 2004

In this paper, the Eigen-RAKE receiver in wideband direct sequence code-division multiple access(DS-CDMA) systems with downlink smart antenna is analyzed for different spreading bandwidths(1.25 MHz, 5 MHz, 10 MHz) and different channel environments(macro, micro). The realistic spatio-temporal wideband multipath channel is assumed, one of which is standardized multiple-input single-output(MISO) radio channel model for WCDMA link-level simulations proposed by $3^{rd}$ generation partnership project(3GPP) contributions. We assumed spatial scattering phenomenon in which many unresolvable path signals within a limited range of spatial angle simultaneously contribute to the signals received at the receiver. Several multipaths within one chip are distinguished into each one and the first multipath components are selected as the desired signal and the others are considered self-interference. Downlink DS-CDMA system with eigenbeamformer using wider bandwidth present better performance than that using narrow bandwidth system by employing Eigen-RAKE receiver of many number of branches. It is shown that the downlink eigenbeamformer is more effective in typical urban macro cellular environments when using Eigen-RAKE receiver.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.337-343
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• 2012

NREL(National Renewable Energy Laboratory) Baseline controller conduct using method proposed RISO National Laboratory in Region 3. which designed the blade-pitch control system using a single degree-of-freedom model of the wind turbine. Idealized PID-Controlled rotor-speed error will respond as a second-order system with the natural frequency and damping ratio. RISO proposed specific natural frequency(=0.6 rad/s) and damping ratio(=0.7). If specific Eigen value apply to NREL 5 MW wind turbine, differ with pitch respond for simulation results of RISO report. Variation of specific eigen value investigate performance of NREL 5 MW wind turbine.

• Structural Engineering and Mechanics
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• 제75권5호
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• pp.541-557
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• 2020

A novel family of controllable, dissipative structure-dependent integration methods is derived from an eigen-based theory, where the concept of the eigenmode can give a solid theoretical basis for the feasibility of this type of integration methods. In fact, the concepts of eigen-decomposition and modal superposition are involved in solving a multiple degree of freedom system. The total solution of a coupled equation of motion consists of each modal solution of the uncoupled equation of motion. Hence, an eigen-dependent integration method is proposed to solve each modal equation of motion and an approximate solution can be yielded via modal superposition with only the first few modes of interest for inertial problems. All the eigen-dependent integration methods combine to form a structure-dependent integration method. Some key assumptions and new techniques are combined to successfully develop this family of integration methods. In addition, this family of integration methods can be either explicitly or implicitly implemented. Except for stability property, both explicit and implicit implementations have almost the same numerical properties. An explicit implementation is more computationally efficient than for an implicit implementation since it can combine unconditional stability and explicit formulation simultaneously. As a result, an explicit implementation is preferred over an implicit implementation. This family of integration methods can have the same numerical properties as those of the WBZ-α method for linear elastic systems. Besides, its stability and accuracy performance for solving nonlinear systems is also almost the same as those of the WBZ-α method. It is evident from numerical experiments that an explicit implementation of this family of integration methods can save many computational efforts when compared to conventional implicit methods, such as the WBZ-α method.

• 한국산학기술학회논문지
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• 제19권12호
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• pp.32-40
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• 2018

열 교환기/원자로의 과도한 진동을 방지 하려면 진동해석을 설계 단계에서 수행해야 한다. 진동 문제에서 고유 진동수의 정보는 열 교환기/원자로의 안전성을 평가하기 위하여 요구된다. 본 논문은 일단 지지보에 발생되는 고유치 문제를 해석하기 위하여 수치해석 방법인 Galerkin의 방법을 기술하였다. 일단 지지보는 자유단 끝점 또는 모드의 노드 포인트에 부가 질량과 스프링에 의하여 구속되어 있다. 수치해석으로 구한 고유진동수는 간단한 해석 방법과 간단한 테스트에 의하여 각각 구한 결과와 비교 되었다. Galerkin의 방법을 사용하여 논의된 일단 지지보의 고유 진동수를 구할 수 있음을 보였다. 부가 질량 증가함에 따라 고유 주파수는 감소하며 스프링 힘의 증가에 따라 고유 주파수는 상승함을 보였다. 무거운 부가 질량은 가연성 배관의 지지대 역할을 함을 보였다. 일단 지지보의 끝단에 설치된 부가 질량의 경우에 개발된 기존의 어림적 해석 방법으로도 일차 모두의 고유 진동수를 비교적 정확하게 구할 수 있음을 알 수 있었다.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.123-130
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• 2004

The automobile suspension system is composed of parts that affect performances of a vehicle such as ride quality, handling characteristics, straight performance and steering effort, etc. Moreover, by using the finite element analysis the cost for the initial design step can be decreased. In the design of a suspension system, usually system vibration and structural rigidity must be considered simultaneously to satisfy dynamic and static requirements simultaneously. In this paper, we consider the weight reduction and the increase of the first eigen-frequency of a suspension part, the upper control arm, especially using topology optimization and size optimization. Firstly, we obtain the initial design to maximize the first eigen-frequency using topology optimization. Then, we apply the multi-objective parameter optimization method to satisfy both the weight reduction and the increase of the first eigen-frequency. The design variables are varying during the optimization process for the multi-objective. Therefore, we can obtain the deterministic values of the design variables not only to satisfy the terms of variation limits but also to optimize the two design objectives at the same time. Finally, we have executed reliability based optimal design on the upper control arm using the Monte-Carlo method with importance sampling method for the optimal design result with 98％ reliability.

• 대한전자공학회논문지TC
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• 제46권7호
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• pp.6-12
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• 2009

본 논문에서는 다중 사용자 환경 다중 안테나 시스템에서 고유값 기반 스케줄링을 수행하기 위한 채널 정보(CSI: channel state information)를 각 사용자의 채널 상태에 따라 선택적(opportunistic)으로 피드백하기 위한 기법을 제안하고 있다. 3GPP(3rd generation partnership project) SMC(spatial multiplexing channel) 채널 모델에 의하면 도심지역에서 다중 사용자 다중 입출력(MU-MIMO: multiuser multiple input multiple output) 시스템은 안테나간의 높은 상관도(correlation)에 의해 시스템 용량(capacity)이 크게 저하된다. 이를 해결하기 위해 제안된 고유값 기반 스케줄링 기법의 경우 상관도에 의한 시스템 용량 저하를 완화시킬 수 있지만, 다중 사용자 다이버시티 이득(multiuser diversity gain)을 충분히 얻지 못하는 단점이 있다. 본 논문에서는 고유값 기반 스케줄링 기법을 바탕으로 다중 사용자 다중 입출력 시스템에서 평균적인 피드백 용량의 증가가 크지 않으면서, 다중 사용자 다이버시티 이득을 크게 향상 시킬 수 있는 선택적 채널 정보 피드백 기법을 제안하고 있다. 컴퓨터 모의 실험 결과를 통해서 본 논문에서 제안한 선택적 피드백 기법을 통해 시스템 용량 개선 효과를 확인할 수 있다.