• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 1호
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• pp.327-330
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• 1998

Wave propagation in inhomogeneous elastic media is studied by using the Fourier method, where the spatial derivatives are computed by the FFT algorithm, while the time derivatives are expanded into the second order finite different expansion. For numerical examples, wave propagation in the layered half-plane are investigated. The comparisons of numerical and analytic results shows good agreement.

• Tribology and Lubricants
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• 제16권3호
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• pp.218-222
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• 2000

Finite element equations by using fast Fourier transformation were formulated for studying temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components. The program developed by using FFT-FEM that combines Fourier transform techniques and the finite element method, was applied to the sliding bearing system. Numerical prediction obtained by FFT-FEM was in an excellent agreement of experimental temperature measurements.

• 대한수학회지
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• 제44권2호
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• pp.455-466
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• 2007

The zero-distribution of the Fourier integral $${\int}^{\infty}_{-{\infty}}\;Q(u)e^{p(u)+^{izu}du$$, where P is a polynomial with leading term $-u^{2m}(m\;{\geq}\;1)$ and Q an arbitrary polynomial, is described. To this end, an asymptotic formula for the integral is established by applying the saddle point method.

• Nuclear Engineering and Technology
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• 제34권4호
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• pp.314-322
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• 2002

A new extrapolation method is developed and applied to the additive angular dependent rebalance (AADR) acceleration for discrete ordinates neutron transport calculations. With this extrapolation, the convergence of AADR solution for distinct discretizations between the high- order and low-order equations is remarkably improved and thus the “inconsistent discretization problem” is resolved. Fourier analysis is also performed to find the optimal extrapolation and weighting parameters, which give the smallest spectral radius. The numerical tests demonstrate that the AADR with extrapolation works well as predicted by the Fourier analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.87-88
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• 2015

본 논문에서는 제주풍력단지에 대한 측정 데이터(measured wind power outputs)를 기반으로 Fast Fourier Transform(FFT)을 실시하고, 이를 이용하여 각 풍력발전단지의 주파수 특성에 대해 분석해보고자 한다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.638-643
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• 1994

• 한국광학회:학술대회논문집
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• 한국광학회 1996년도 Advance Program of 13th optics andquantum Electronics conference, 1996제13 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.50-50
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• 1996

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1108-1117
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• 2005

A robust damage detection method using short-time Fourier transform and beating phenomena is presented as an estimating tool of the healthiness of large structures. The present technique makes use of beating phenomena that manifest themselves when two signals of similar frequencies are added or subtracted. Unlike most existing methods based on vibration signals, the present approach does not require an analytic model for target structures. Furthermore, the main advantage of the proposed method compared to the competing diagnostic method using vibration data is its robustness. The proposed method is not affected by the amplitude of exciting signals and the location of exciting points. From a measuring view point. the location of sensing point have no influence on the performance of the present method. With a view to verifying the effectiveness of this method. a series of experiments are made and the results show its possibility as a robust damage diagnostic method.

• 전기학회논문지
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• 제61권4호
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• pp.542-548
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• 2012

This study presents a new method of system modeling by using the Discrete Fourier Transform for the position control system of DC Motor. And the proposed method is similar to the method of System Identification by analysis of correlation of the measured input-output data. The measured output signals are transformed to the frequency domain using DFT. The Fourier Spectrum of the transformed signals is used for knowing to the feature of having an important effect on the system. And transfer function of the second order system is estimated by the dominant parameter which is computed in the magnitude and the phase of Fourier spectrum of the transformed signals. In addition, the output signal includes the unique feature of system. So, although the basic parameter of the system is unknown for us, the proposed method has an advantage to system modeling. And the controller is easily designed by the estimated transfer function. Thus, in this paper, the proposed method is applied to the system modeling for the position control system of DC Motor and the PD-controller is designed by the estimated model. And the efficiency and the reliability of the proposed method are verified by the experimental result.

• 한국콘텐츠학회논문지
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• 제10권1호
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• pp.78-86
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• 2010

스펙트럼 센싱 기술은 차세대 무선통신 기술들 중 하나인 Cognitive Radio (CR) 시스템에서의 핵심 기술이다. 본 논문은 CR 기술 기반의 효율적인 스펙트럼 센싱을 위하여 대상 신호의 시간-주파수 측면의 분석을 위한 알고리즘인 Short Time Fourier Transform을 적용하는 방법을 제안하였다. STFT에 적용된 윈도우는 Kaiser Window이며, 그 중첩 정도는 50%로 규정하였다. 시뮬레이션을 위해 6MHz 대역폭을 가진 DVB-H 신호를 입력 신호로 하였으며, Modified Periodogram Method, Welch's Method와의 비교를 통하여 제안한 알고리즘의 성능을 확인하였다. 또한, 임베디드 보드를 통하여 스펙트럼 센싱 모듈을 구현하였다.