• 전자공학회논문지
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• 제52권2호
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• pp.97-105
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• 2015

이 논문은 SIMD 구조를 갖는 프로세서에서 FFT 연산을 효과적으로 처리하는 방법에 대한 것이다. FFT는 디지털 신호처리 분야에서 널리 사용되는 범용 알고리즘으로 이의 효과적인 처리는 성능 향상에 있어서 매우 중요하다. Bruun 알고리즘은 반복적인 인수분해를 통해 구현되는 FFT 알고리즘으로, 널리 사용되는 Cooley-Tukey 알고리즘에 비해 복소수 곱셈이 아닌 실수 곱셈으로 대부분의 동작을 수행하는 장점을 가지고 있으나, SIMD 프로세서에서 구현하는 데는 벡터 데이터의 정렬 형태가 복잡하고 연산에 필요한 계수들을 저장할 메모리를 더 필요로 하는 단점이 있다. 실험 결과에 따르면 길이 1024인 FFT 연산을 SIMD 프로세서에서 수행하는데 있어서 Bruun 알고리즘은 Cooley-Tukey 알고리즘에 비해서 약 1.2배의 더 높은 처리성능을 보이지만, 약 4 배 더 큰 데이터 메모리를 필요로 한다. 따라서 데이터 메모리에 대한 제약이 큰 경우가 아니라면 SIMD 프로세서에서 Bruun 알고리즘이 FFT 연산에 적합하다.

• 전자공학회논문지B
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• 제30B권9호
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• pp.27-35
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• 1993

In this paper, a new algorithm for high level security and quality of speech is proposed. The algorithm is based on the rearrangement of the fast fourier transform (FFT) coefficients with pre and post filter process, hamming window and adaptive pseudo spectrum insertion. Then, the pre and post filters are used for the whitening of speech spectrum and the adaptive pseudo spectrum is inserted for the unclassification of silence/speech. Also, the hamming window technique is applied for the robustness to the syncronization error in the telephone line. According to the simulation results, it can be seen that the security of scrambled signal and the quality of descrambled signal have been improved fairly in both subjective and objective performance test and the new FFT scrambler is robust to the synchronization error.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.32-41
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• 1999

In this study, a new knocking control algorithm was developed using the knock threshold value auto-correction algorithm. This algorithm uses the Fast Fourier Transform9FFT) method by measuring cylinder block vibration signals of a 1498 cc four-cylinder spark ignition engine. The experimental results show the proposed knock control algorithm provides improved performance compared to existing methods. The results also show that the proposed FFT algorithm provides real-time adjustment of the knock threshold value.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권2호
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• pp.60-64
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• 2001

The degradation process of silicone rubber was investigated by leakage current monitoring in Inclined-Plane method. DAS (Data Acquisition System) with 12-bit, 8-channel A/D converter was prepared. Average current, cumulative charge, current waveform and the number of peak pulses were measured on-line. And, FFT (Fast Fourier Transform) analysis was performed with stored current waveform. Besides, maximum erosion depth was measured in order to use as the indicator of the degradation process. So, the results of leakage current components and maximum erosion depth measurements were compared to find one or more components which have trends of changing similarly to that of erosion process. The result suggests that the ratio of peak current to r.m.s. current, harmonic contents and the number of peak pulses are well corresponding with the degradation process.

• Journal of Korean Vacuum Science & Technology
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• 제3권2호
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• pp.107-111
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• 1999

We developed the experimental function (ERF) which can be used for the numerical curve fitting analysis in photoelectron spectroscopy (PES). We selected the core-levels of Ag 3d5/2 and Au 4f7/2 to obtain the ERF from the measured core-level spectra. For the numerical fourier transformation we applied the fast transform (FFT) algorithm. we considered optical (Wiener) filtering with the FFT due to noise and used Hann window function to remedy the information leakage in frequency domain due to discrete and finite sampling of measurement. The comparison of the curve fitting results using the ERF obtained in this work and the mathematical response function with a gaussian in the conventional approach shows clearly the improvement of the curve fitting analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.566-567
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• 2002

In this study, the measurement part in which the Fast Fourier Transform module and orthogonal filter are included is proposed. Protection relay should has a high precision and concurrently real-time response. Because FFT routine give micro-processor heavy burden and orthogonal filter reduces precision, both FFT module and orthogonal filter are designed to have different sampling frequency.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.259-262
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• 1999

본 논문에서는 먼저 피아노 음을 FFT(Fast Fourier Transform)를 이용하여 주파수 영역으로 변환을 한 후, 크기(magnitude)와 위상(phase)에 대한 특성들을 분석한다 이 분석한 결과를 가지고 모델링을 함으로써 피아노 원음에 근접한 음을 만들 수 있다. 크기에서의 특성은 기본주파수와 고조파 부분에서 다른 부분에 비해 크기의 차이가 크다. 그래서 기본주파수와 고조파부분은 오차를 줄이기 위해 적은 데이터를 가지고 곡선의 적합성(Curve Fitting) 방법을 이용하고, 노이즈 부분은 기본주파수 전·후의 노이즈가 피아노 음색 특성에 중요한 역할을 하므로, 이 부분을 최고점과 최저점른을찾아 선형으로 모델링 하였고, 나머지 노이즈 부분은 적은 값을 가지므로 많은 데이터를 가지고 곡선의 적합성을 이용하였다. 위상은 크기에서 모델링한 결과를 바탕으로 모델링을 하였다 모델링을 한 결과를 가지고 역변환 FFT를 하면 피아노 원음에 매우 근접한 음을 생성할 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.77-82
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• 2004

There were many researches about the chatter vibration occur in the cutting process of machine tools. But there are in sufficient research parts ; the frequency about the chatter vibration and its characteristics and its nonlinear properties. This paper measured signals of vibration that occur before and immediately after and after the chatter vibration. This signals were analyzed through autospectrum obtained by the Fast Fourier Transform(FFT). And then, the nonlinear characteristis were analyzed by cepstrum analysis through FFT of autospectrun.

• Journal of Welding and Joining
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• 제18권4호
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• pp.82-86
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• 2000

Gas metal arc welding(GMAW) is regarded as one of the best candidate for welding automation in industrial joining application. It is important to monitor the weld quality for the high performance weld automation. In GMAW, weld quality is closely related to arc stability especially. In this paper, arc light signal is measured and spectrum analyzed to the detect the variation of the weld quality. The FFT of the signal showed that the amplitude variance of FFT power spectrum was very large in poor weld process such as the decrease of weld bead width and height. The results show that it is possible to detect the weld defect position in weld process.

• 한국컴퓨터정보학회논문지
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• 제20권7호
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• pp.57-64
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• 2015

In this paper, we propose a design of microwave motion detector using X-band doppler radar sensor to minimize the power consumption. To minimize the power consumption and implement battery operated system, pulse input with 2 KHz, 4% duty cycle is exerted on the doppler radar sensor. In order to simplify the process of working with ATmega2560 microcontroller unit, Arduino compatible board is designed and implemented. Arduino is open source hardware and many library software is published as open source tools. Smartphone app is also proposed and designed as a real-time user interface of the motion detector. The SQLite database on the Android mobile operating system is used for recording raw data of motion detection for post-processing job, such as fast Fourier transform (FFT). Bluetooth interface module is implemented on the motion detection board as a wireless communication interface to the smartphone. The speed of human movement is identified by post-processing FFT.