• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.10-12
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• 2002

최근에 많은 새로운 타입의 어플리케이션에서 정보 시스템들에 대한 사용의 증가로 인해 연속 질의들은 여러 연구 프로젝트들에서 초점이 되고 있으며 연구가 활발히 진행되고 있다. 특히 시계열에 대해서 미래의 값에 대한 예측 모델과 FFT(Fast Fourier Transform)을 이용하여 새로운 값이 입력될 때마다 신속하게 응답할 수 있는 이웃에 관한 연속 질의에 대해 이미 연구되었다. 그러나 이것은 이웃에 관한 질의이며 또한 방대한 데이터를 처리함에 있어서 매우 효율적이지 못하다. 이 논문에서는 시계열에 있어서 예측 모델을 이용하여 미래의 값을 예측한다. 다음 DFT(Discrete Fourier Transform)을 이용하여 변환한 후 R*-tree를 구성하고, 새로운 값이 입력될 때마다 신속하게 유사성 시계열들을 찾아서 응답하는 연속 범위 질의 과정과 시스템 구조에 대해 제안한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.196-200
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• 1987

The following methods are proposed for implementing digital dual tone multi-frequency (DTMF) receiver: using infinite impulse response(IIR) digital filters, period-counting algorithm, discrete Fourier transform(DFT), and fast Fourier transform(FFT)[2]. The PARCOR(Partical Correlation) analysis method which has been widly used in the speech signal processing area is applied to the dual tone multi-frequency(DTMF) signal detection. This method is easy to implement digitally and stronger to digit simulation of speech than any other methods proposed up to date. Since sampling rate of 4KHz is used in the DTMF receiver for the detection of input DTMF signal originally sampled at 8KHz, it effects two times higher multiplexing efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2437-2442
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• 2013

OFDM Wi-Fi AP is susceptible to the co-channel interference. As a countermeasure, the insertion of a smart has been addressed. Despite of the guaranteed efficiency, the complexity of the post-FFT algorithm often keeps itself from being selected as the countermeasure. Instead, simply constructed pre-FFT smart antenna of which the algorithm is based on the received signal covariance matrix is commonly used and the mathematical modeling of it has been deployed. Computer simulations evaluating the improved BER characteristics of the proposed pre-FFT using the covariance matrix of channel estimator output have been carried out. It has been demonstrated that channel matrix output based smart antenna is superior to that using received signal covariance matrix.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1365-1368
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• 2002

OFDM은 제4세대 변조기술로 일컬어지는 방식이다. 이는 최근 유럽에서 디지털 오디오 방송(DAB)과 디지털 비디오 방송(DVB)에 표준이 되었으며, IEEE 802.11a 무선 LAN 에서도 이 방식을 채택했고, ADSL, VDSL 등에서도 사용되어지고 있다. 본 논문에서는 이러한 OFDM 방식의 핵심이라고 할 수 있는 64포인트 FFT(Fast Fourier Transform)하드웨어 프로세서의 여러 가지의 구현된 예를 비교 분석하고, 가장 효율적인 방법인 Radix-2 SDF(Singlepath Delay Feedback)[1] 방법을 개선하여 새로운 구조를 제안하였다. 동일한 속도 성능을 가지는 여러구조 중에서 적은 수의 지연소자를 활용하여 FFT 크기를 작게 한 것이 SDF 방식으로 가장 널리 사용되고 있다. 본 논문에서는 SDF 방식이 내부적으로 4개의 복소곱셈기를 필요로 하는데 비해 2개의 복소곱셈기만을 사용하는 구조로 변형하고 컨트롤을 조절하여 새로운 구조를 설계하였다. 구현한 결과, FFT에서 전체 구조의 약 80%를 차지하는 복소곱셈기의 수를 절반으로 줄여 FFT 하드웨어 크기를 SDF 방식의 60% 정도로 줄일 수 있게 되었고, 이러한 구현방식은 64포인트 FFT만이 아닌 더 큰 크기의 FFT를 구현함에 있어서도 동일하게 적용할 수 있으며 현재 국내외에 발표된 논문 중 성능 대 면적비가 가장 우수한 구조이다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.4 s.334
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• pp.61-68
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• 2005

A chip, which can fast encoder the audio data to AAC (Advanced Audio Coding) LC(Low Complexity) that is MPEG-2 audio standard, has been designed on the basis of a 32 bits DSP core and fabricated with 0.25um CMOS technology. At first, the various optimization methods for implementing the algerian are devised to reduce the memory size and calculation cycles. FFT(Fast Fourier Transform) hardware block is added to the DSP core to get the more reduction of the calculation cycles. The chips has the size of $7.20\times7.20 mm^2$ and about 830,000 equivalent gates, can carry out AAC encoding under 70MIPS(Million Instructions per Second).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1492-1499
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• 2020

A weather radar system generally shows the weather phenomena related with rainfall and wind velocity. These systems are usually very helpful to monitor the relatively high altitude weather situation for the wide and long range area. However, since the weather hazards due to the strong hail and heavy rainfall occurring locally are observed frequently in recent days, it is important to detect these wether phenomena. For this purpose, it is necessary to detect the fast varying low altitude weather conditions. In this environment, the effect of surface clutter is more evident and the antenna dwell time is much shorter. Therefore, the conventional Doppler spectrum estimation method may cause serious problems. In this paper, the AR(autoregressive) Doppler spectrum estimation methods were applied to solve these problems and the results were analyzed. Applied methods show that improved Doppler spectra can be obtained comparing with the conventional FFT(Fast Fourier Transform) method.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.10
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• pp.27-36
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• 1992

This paper proposes a numerical method of motion planning for manipulators using Foruier series. For a redundant manipulator, we predetermine the trajectories of redundant joints in terms of the Nth partial sum of the fourier series. then the optimal coefficients of the fourier series are searched by the Powell's method. For a nonredundant or redundant manipulator, CS02T-continuous smooth joint trajectory for a point-to-point task can be obtained while considering the frequency response. We apply the proposed method to the 3-link planar manipulator and the PUMA 560 manipulator. To show the validity of the proposed method, we analyze solutions by the Fast Fourier Transform (FFT). Also, several features are discussed to obtain an optimal solution.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.309-312
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• 2004

This paper proposes the architecture of UWB OFDM communication system. More high data rate is requested in the 128-point FFT/IFFT of the UWB OFDM communication system than the conventional communication systems. So, the proposed architecture uses pipeline and parallel architecture. For a highly efficient architecture, the optimal clipping power and the input quantization bits are found in simulation. The hardware complexity of the proposed architecture is presented is consideration of Adder, Register and Complex Multiplier.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.162-167
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• 2012

This paper proposes a speech processing system based on a model of the human auditory system and a noise reduction neural network with fast Fourier transform (FFT) amplitude and phase spectrums for noise reduction under background noise environments. The proposed system reduces noise signals by using the proposed neural network based on FFT amplitude spectrums and phase spectrums, then implements auditory processing frame by frame after detecting voiced and transitional sections for each frame. The results of the proposed system are compared with the results of a conventional spectral subtraction method and minimum mean-square error log-spectral amplitude estimator at different noise levels. The effectiveness of the proposed system is experimentally confirmed based on measuring the signal-to-noise ratio (SNR). In this experiment, the maximal improvement in the output SNR values with the proposed method is approximately 11.5 dB better for car noise, and 11.0 dB better for street noise, when compared with a conventional spectral subtraction method.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.109-116
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• 2006

This paper presents a real time distance measuring device using a W-band linear frequency modulated continuous wave(FMCW) radar and TMS320C6701 digital signal processor(DSP). We used FFT operation for measuring distance with the beat signals and the results of FFT could be converted to distance with ease. We presented how to implement a real time miniaturized hardware system including network protocols using a single DSP core. Also how to control the modulation signal of FMCW system to compensate the VCO nonlinearity using the Time Gating control of DSP is presented. We have shown that the proposed system has good performances for measuring distance in real time via outdoor environment experiments.