• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.87-88
• /
• 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.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.39 no.11
• /
• pp.62-71
• /
• 2002

This paper presents new DSP (Digital Signal Processor) instructions and their hardware architecture for high-speed FFT. the instructions perform new operation flows, which are different from the MAC (Multiply and Accumulate) operation on which existing DSP chips heavily depend. The proposed DPU (Data Processing Unit) supporting the instructions shows two times faster than existing DSP chips for FFT. The architecture has been modeled by the Verilog HDL and logic synthesis has been performed using the 0.35 ${\mu}m$ standard cell library. The maximum operating clock frequency is about 144.5 MHz.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.7
• /
• pp.1024-1031
• /
• 2012

In this paper, FMCW type radar level transmitter using correlation analysis method is implemented for precise distance measurement of cargo tank. FMCW type radar level transmitter is the device for distance measurement which calculates the distance by analyzing the beat frequency, that is, the frequency difference between Tx and RX signal from radar antenna using Fast Fourier Transform(FFT), but compensated algorithm like Zoom FFT is needed for the improvement of the frequency precision because the frequency precision of FFT is limited depending on sampling frequency and the number of sampling data. In case of Zoom FFT, the number of sampling data and noisy signal are the main factor influencing the measurement accuracy of Zoom FFT like FFT. Therefore, in order to overcome the limited environment and achieve the precise measurement, correlation coefficient is used for the distance measurement and the errors of measurement are verified to be in the range of ${\pm}1mm$.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.2D
• /
• pp.323-334
• /
• 2011

In this study, we performed the residual geoid modeling using the FFT and LSC methods in context of application of R-R (Remove and Restore) technique as a general technique for gravimetric geoid model in order to propose the effective way of geoid determination in Korea. For this, a number of data compiled for residual geoid modeling by the multi-band spherical FFT method with Stoke's formula and LSC method as known as statistical method. The geometric geoidal heights obtained from 503 GPS/Levelling data were used for inducing the various elements and proper computation process which should be considered for improving the accuracy of residual geoid modeling. Finally, we statistically compared the results of residual geoid heights between FFT and LSC methods and reviewed then the proper way of residual geoid modeling to the region of Korea. As the results of comparison, LSC method is not suitable for residual geoid modeling in Korea due to the noise and lack of gravity observations and the effects of local characteristics, while FFT method by applying Stokes' integral with proper cap size and modified kernel which provides the better accuracy of residual geoid heights up to 10 cm more than those of LSC method.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.14 no.6
• /
• pp.26-30
• /
• 1977

Redundancies in the Calculation of DFT and FFT are analized and new algorithms are proposed which are capable of reducing the machine time by a considerable amount. New extensions of T.D C.F. and T.D.F.T. are given for the discrete case which permit a deeper insights for the techniques of digital signal Proessing i. e. Discrete Fourier Transform, Convolution Sum and Correlation sequences.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1071-1074
• /
• 2002

In this paper, power quality analysis system is proposed where voltage or current waveforms are nonsinusoidal. The proposed system relies on the FFT algorithm to compute real and reactive power. The advantage of system is that harmonic analysis is carried out on a period of the input signal. The proposed system is based on FFT processor which is designed using VHDL(Very high-speed integrated circuit Hardware Description Language). In the design of FFT processor, radix- $2^2$ is adopted to reduce several complex multipliers for twiddle factor. Complex multiplier is implemented as only shifters and adders. Therefore, the system is able to have both high hardware efficiency and high performance.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.3
• /
• pp.116-122
• /
• 2006

A fast scan digital-IF FFT receiver at the radio communication band is presented for spectrum monitoring applications. It is composed of three parts: RF front-end, fast LO board, and signal processing board. It has about 19GHz/s scan rate, multi frequency resolution from 10kHz to 2.5kHz, and high sensitivity of below -99dBm. The design and performance analysis of the digital-IF FFT receiver are presented.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.05a
• /
• pp.1777-1780
• /
• 2005

OFDM(Orthogonal Frequency Division Multiplexing)은 제 4 세대 기술로 일컬어지는 변조 방식으로 최근 유럽의 디지털 오디오 방송(DAB)과 디지털 비디오 방송(DVB)에 표준으로 사용되고 있으며, IEEE 802.11a 무선 LAN 및 디지털 가입자라인 xDSL 에서도 사용되고 있다. 본 논문에서는 OFDM 모뎀 구현의 핵심이라고 할 수 있는 64-포인트 FFT(Fast Fourier Transform) 프로세서의 여러 가지 구조를 분석하고, 이들과 비교하여 성능 대 면적 비를 획기적으로 향상시킨 새로운 FFT 프로세서인 Radix-4,2 SIC (Single Instruction Computer) 구조를 제안하였다. 본 논문에서 제안하는 SIC 구조는 버터플라이 연산의 재사용을 극대화하였으며 Radix-4,2 알고리즘을 사용함으로써 FFT 프로세서에서 면적의 80%를 차지하는 복소곱셈기의 수를 감소시켜 크기를 획기적으로 줄인 결과를 보여 준다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.06c
• /
• pp.28-30
• /
• 2006

XML 문서의 유사성을 비교하는 연구는 XML 문서의 저장 및 검색에 유용하기 때문에 많은 연구가 진행되었다. XML 문서의 유사성 연구는 크게 edit-distance를 이용하는 방법, 문서의 그래프 모델을 이용하는 방법, 문서의 매트릭스 모델을 이용하는 방법 등이 있다. 최근에는 문서를 encoding 하고 푸리에 변환을 이용하는 방법이 보고되었다. 본 논문에서는 XML 문서를 함수로 변환하고 FFT를 적용하여 문서의 구조적 유사성을 비교하는 새로운 방법을 제안한다. 제안하는 방법은 JAXP로 구현하였으며 XML 문서의 구조를 분석하여 함수로 변환하였다. 그리고 함수에 FFT를 적용하여 XML 문서의 구조적 유사성을 비교하였다. FFT 비교 결과는 XML 문서의 함수 변환이 적합한 것임을 보여주었으며 비교 결과는 예상된 결과를 보여주었다.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.7
• /
• pp.57-64
• /
• 2009

Based on this article, I have analyzed the OFDM system which applies three types of equalizer forms in the two-path channel of the microwave baseband. The Two-path channel of microwave baseband had been simulated through the Rummler channel. In the Two-path channel, the OFDM system which has three forms of equalizer has been analyzed and the result is, equalizer 1-tab has great improvement in efficiency compared with Pre-FFT 11-tab which has noise power ratio less than 18dB. On the contrary, if the symbol energy to the noise ratio is more than 18dB, the equalizer which applies Pre-FFT 11-tab has greater efficiency compared to the equalizer which applies 1-tab frequency. Last but not least, the OFDM system which applies Dual equalizer has better efficiency compared to the system which has 1-tab frequency and equalizer which applies Pre-FFT 11-tab.