• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1060-1069
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• 2016

In this paper, we introduce the fingerprint recognition system based on Radial Basis Function Neural Network(RBFNN). Fingerprints are classified as four types(Whole, Arch, Right roof, Left roof). The preprocessing methods such as fast fourier transform, normalization, calculation of ridge's direction, filtering with gabor filter, binarization and rotation algorithm, are used in order to extract the features on fingerprint images and then those features are considered as the inputs of the network. RBFNN uses Fuzzy C-Means(FCM) clustering in the hidden layer and polynomial functions such as linear, quadratic, and modified quadratic are defined as connection weights of the network. Particle Swarm Optimization (PSO) algorithm optimizes a number of essential parameters needed to improve the accuracy of RBFNN. Those optimized parameters include the number of clusters and the fuzzification coefficient used in the FCM algorithm, and the orders of polynomial of networks. The performance evaluation of the proposed fingerprint recognition system is illustrated with the use of fingerprint data sets that are collected through Anguli program.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.319-327
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• 2011

An iterative technique based on orthogonal filters and frequency tracking is proposed to estimate harmonic components in power systems. The technique uses frequency interpolation to estimate fundamental frequency and harmonics when the nominal frequency of the signal is a non-integer value. Due to the number of computations involved during the generation of filter coefficients, an offline computation is suggested. Beneficial features of the proposed technique include fixed sampling rate and fixed data window size. The performance of the proposed technique is examined by simulating different power system operating conditions and evaluating the data from these simulations. A technique based on Fast Fourier Transform is also used to estimate the harmonic components for all the simulated signals. These estimates are compared with those obtained from the proposed technique. Results show that the proposed technique can converge to the accurate fundamental frequency and therefore, provide accurate harmonic components even when the fundamental frequency is not equal to the nominal frequency.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.13 no.1
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• pp.52-58
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• 2002

The pitch range of the human voice is variable, extending from chest register to falsetto. Although numerous studies have investigated after laryngeal mechanism description of registers, systematic and objective studies were lack. The purpose of this study was to analyze and compare head register with chest register of singers acoustically. Fifteen healthy tenor major students were selected. Fifteen healthy untrained adults were the control group for this study. Long term average(LTA) power spectrum using the Fast Fourier transform(FFT) algorithm and Linear predictive coding (LPC) filter response were made during /a/ sustained in both head(G4, 392Hz) md chest registers (C3, 131Hz). Statistical analysis was performed using Mann-Whitney test. In the LTA power spectrum, head register of singer has increased level(energy gain) in the frequency band of 2.2-3.4kHz(p<0.01), and 7.5-8.4kHz(p<0.01, p<0.05). Chest register of singer has increased level in the frequency band of 2.2-3.1kHz(p<0.01), 7.8-8.4kHz(p<0.05) and around 9.6kHz(p<0.01). LTA power spectrum reveals a peak of acoustic energy around 2500Hz known as the singer's formant and another peak of acoustic energy around 8000Hz in singer's voice.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1024-1031
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• 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 ${\pm}1mm$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.605-608
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• 2009

It is necessary to estimate the Doppler spectrum for each range cell for the extraction of useful information from the return echoes in radar systems used for the remote sending purpose. However, The conventional spectrum estimation method, FFT(Fast Fourier Transform), called the Doppler filter bank, causes the frequency resolution problem if the dwell time is relatively short. This short acquisition time also spreads the side lobe levels of return echoes further, resulting in difficulties for the discrimination of weak target signals included in relatively strong target echoes. Therefore, in this paper, the efficient Doppler spectrum estimation methods are compared and investigated through the parameter spectrum estimation in the time domain to overcome these problems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.568-575
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• 2022

This paper is a study on frequency analysis and electronic noise reduction of energy storage system (ESS). We acquired 4 necessary data for about 2 minutes and 4 seconds using a sampling frequency of 10,000 Hz in ESS. Fast Fourier transform (FFT) was used for electronic noise analysis from the acquired data. As a result, it was confirmed that DC component, fundamental wave, second and higher harmonic component exist. For the attenuation of harmonics, low-pass filter (LPF) was applied. We confirmed that an attenuation of approximately 59.3% appears from the second harmonic. The presence of many harmonic components in the data of the ESS was expected to occur due to the insufficiency of optimization among the modules inside the ESS. Therefore, we propose that a national certification system for ESS should be introduced to settle down the issue properly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.375-382
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• 2010

This paper presents the extraction of natural frequencies and mode shapes of a cable-stayed bridge using data acquired from GNSS. The response signals of 6 GNSS measuring points installed at the Seohae cable-stayed bridge are used for analysis of dynamic characteristics. Using normalization process and a third order Butterworth filter for the measured signals, the related pass band's signals have been isolated. Then, the acceleration data by double differentiation for these signals are obtained. Total five natural frequencies have been extracted by the fast Fourier transform and compared to the results of different studies. For the acceleration obtained from GNSS signals, the mode shapes of the bridge have been successfully extracted by TDD technique.

• Journal of the Korean Geotechnical Society
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• v.38 no.12
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• pp.91-101
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• 2022

The 1995 Kobe earthquake caused a massive damage to the Port of Kobe. Therefore, it was pointed out that it was impossible to design port structures for Level II (Mw 6.5) earthquakes with quasi-static analysis and Allowable Stress Design methods. In Japan and the United States, where earthquakes are frequent, the most advanced design standards for port facilities are introduced and applied, and the existing seismic design standards have been converted to performance-based design. Since 1999, the Korean Port Seismic Design Act has established a definition of necessary facilities and seismic grades through research on facilities that require seismic design and their seismic grades. It has also established a performance-based seismic design method based on experimental verification. In the performance-based seismic design method of the breakwater proposed in this study, the acceleration time history on the surface of the original ground was subjected to a fast Fourier transform, followed by a filter processing that corrected the frequency characteristics corresponding to the maximum allowable displacement with respect to performance level of the breakwater and the filtered spectrum. The horizontal seismic coefficient for the equivalent static analysis considering the displacement was calculated by inversely transforming (i.e., subjected to an inverse fast Fourier transform) into the acceleration time history and obtaining the maximum acceleration value. In addition, experiments and numerical analysis were performed to verify the performance-based seismic design method of breakwaters suitable for domestic earthquake levels.

• International Journal of Highway Engineering
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• v.3 no.4 s.10
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• pp.137-146
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• 2001

Pavement distresses are one of the most important data for pavement management systems. Inspection machines and its related programs have been used for operating tools in PMS developed in advanced countries. In Korea imported machines and programs for the length price ale utilized to get information of pavement condition from the field This study is launched for developing the program which can detect cracks on asphalt pavement due to many drawbacks in current PMS operation such as improper maintenance work and long resting period when it was broken. The focus of this study is to define principles to analyze pavement surface with digital image processing techniques, to test property of pavement images and to suggest an algorithm that reduces noises at test. To test images, the camera attached on the Automatic Road Analyser(ARAN) was used. Through the FFT images, histogram and statistical values of pavement images, it was found that the images had many noises with high-frequency components against general images, and it was difficult to subdivide pavement images into background or crack. Through several testing with various filters for noise reduction a 3X3 median filter was suggested to reduce noises effectively.

• Nano
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• v.13 no.12
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• pp.1850147.1-1850147.14
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• 2018

In this work, water-soluble and blue-emitting carbon nanodots (CDs) were synthesized from apple peels for the first time via one-step hydrothermal method. The synthetic route is facile, green, economical and viable. The as-prepared CDs were characterized thoroughly by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR), X-ray photoelectron (XPS), fluorescence and UV-Vis absorption spectroscopy in terms of their morphology, surface functional groups and optical properties. The results show that these CDs possessed ultrasmall size, good dispersivity, and high tolerance to pH, ionic strength and continuous UV irradiation. Significantly, the CDs had fast and reversible response towards temperature, and the accurate linear relationship between fluorescence intensity and temperature was used to design a novel nanothermometer in a broad temperature range from 5 to $65^{\circ}C$ facilely. In addition, the fluorescence intensity of CDs was observed to be quenched immediately by Cr(VI) ions based on the inner filter effect. A low-cost Cr(VI) ions sensor was proposed employing CDs as fluorescent probe, and it displayed a wide linear range from 0.5 to $200{\mu}M$ with a detection limit of $0.73{\mu}M$. The practicability of the developed Cr(VI) sensor for real water sample assay was also validated with satisfactory recoveries.