• Speech Sciences
• /
• v.10 no.4
• /
• pp.189-200
• /
• 2003

The objective of this study was to examine two new parameters by which we could screen people with malignant vocal folds. The new parameters were the difference sums and Pearson correlation coefficients between adjacent pairs of intensity level matrices of narrow-band spectra. Audio files from the Korean Disordered Speech Database were analyzed by Praat, a speech analysis software, to obtain matrices of 400 intensity levels at 16 time points of each sustained vowel spectra. We limited our study to 12 normal subjects and 20 patients with malignant vocal folds who recorded at least three Korean vowels at a sound-proofed booth in Busan National University Hospital. Results indicated that the average coefficients of the abnormal subjects were much lower than those of the normal subjects while the average difference sums of the patients were much higher than those of the normal ones. Also, we found that the degree of the malignancy of the vocal folds was related to the coefficients and sums. However, some subjects at the initial stages of cancerous vocal folds yielded almost comparable coefficients and difference sums to those of the normal speakers. Further studies on larger databases will be desirable to set certain criteria or threshold levels for screening people with vocal fold diseases.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1749-1753
• /
• 2003

We proposed several systems for 1Giga bit Modem. The first, Binary ASK(Amplitude Shift Keying) system has a high speed shutter transmitter and no IF(Intermediate Frequency) receiver only by symbol synchronization. The advantage of proposed system is that circuitry is very simple without IF process. The disadvantage of proposed system are that line spectrum occurs interference to other channels, and enhancement to 4-level system is impossible due to its large SNR degradation. The second, Binary phase modulation system has a high speed shutter transmitter and IF-VCO(IF-Voltage Controlled Oscillator) control by base-band phase rotation. Polarity of shutter window is changed by the binary data. The window should be narrow same as above ASK. The advantage of proposed system is which error rate performance is superior. The disadvantage of proposed system are that Circuitry is more complex, narrow pull-in range of receiver caused by VCO and spectrum divergence by the non-linear amplifier. The third, 4-QAM(Quadrature Amplitude Modulation)system has a nyquist pulse transmitter and IF-VCO control by symbol clock. The advantage of proposed system are that signal frequency band is a half of 1GHz, reliable pull-in of VCO and possibility of double speed transmission(2Gbps) by keeping 1GHz frequency-band. The disadvantage of proposed system are that circuit complexity of pulse shaping and spectrum divergence by the non-linear amplifier.

• Journal of the Semiconductor & Display Technology
• /
• v.9 no.2
• /
• pp.1-6
• /
• 2010

Star-like ZnO nanostructures were grown on SI(100) substrates with carbon(C) catalyst by employing vapor-solid(VS) mechanism. The morphologies and structure of ZnO nanostructures were investigated by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectrum, Photoluminescence spectrum. The results demonstrated that the as-synthesized products consisted of star-like ZnO nanostructure with hexagonal wurtzite phase. Nanostructures grown at 1100 were mainly star-like in structure with diameters of 500 nm. The legs of the star-like nanostructures were preferentially grown up along the [0001] direction. A vapor.solid (VS) growth mechanism was proposed to explain the formation of the star-like structures. Photoluminescence spectrum exhibited a narrow emission band peak around 380 nm and a broad one around 491 nm. Raman spectrum of the ZnO nanostructures showed oxygen defects in ZnO nanostructures due to the existence of Ar gas during the growth process, leading to the dominant green band peak in the PL spectrum.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.11
• /
• pp.19-31
• /
• 1996

Spread spectrum method gurantees good performance in digital communication system under multi-path interference and jamming signals. The purpose of this paper is to develop the wireless modem using DS/SS techinque. The transceiver consists of a spread spectrum DQPSK transmitter and a mtching receiver. The system operates with the chipping rate set to 4 Mcps and the number of chips/symbol at 64, making the data rate 62.5 Kbps using QPSK modilation. The receiver section uses a digital matched filter for fast acquisition of burst signals and uses the comparing the BER of proposed system iwth that of narrow bnd system under various additive white gaussian noises. It is showen that the proposed sysem has better performance than narrow band system. When jamming signals is added to the suggested DS/SS system, we also show that the experimental performance (BER) of the suggested wireless modem is almost same as theroretical performance.

• Journal of information and communication convergence engineering
• /
• v.3 no.4
• /
• pp.184-186
• /
• 2005

The effect of power supply noise on the phase noise of a ring oscillator is studied. The power supply noise source in series with DC power supply voltage is applied to a 3 stage CMOS ring oscillator. The phase noise due to the power supply noise is modeled by the narrow band phase modulation. The model is verified by the fact that the spectrum of output of ring oscillator has two side bands at the frequencies offset from the frequency of the ring oscillator by the frequency of the power supply noise source. Simulations at several different frequency of the power supply noise reveals that the ring oscillator acts as a low pass filter to the power supply noise. This study, as a result, shows that the phase noise generated by the power supply noise is inversely proportional to the frequency offset from the carrier frequency.

• Journal of the Society of Naval Architects of Korea
• /
• v.30 no.2
• /
• pp.37-42
• /
• 1993

In this study of statistical characteristics of roll response of ships to narrow band exciting moment generated by passing white noise through a linear filter is investigated. The parameters of linear filler are determined by comparing the results of exciting moment generated through filler equation tilth those evaluated from JONSWAP spectrum. The statistical results of the roll response of shops are presented.

• Journal of IKEEE
• /
• v.21 no.3
• /
• pp.202-210
• /
• 2017

Recently, some variable length adaptive filters which employ variable lengths taps for the input signal statistics are proposed [1-5]. In this paper, a new subband adaptive filter with variable filter tap length is proposed. The proposed subband variable length adaptive filters can optimize filter length for each subband which can result less computational complexities with respect to the conventional full band adaptive filters. When the signal in the full band has narrow spectrum, the conventional full band adaptive requires very long filter taps, whereas the proposed subband variable filter requires less taps with the spectrum split in subband. The computer simulation results reveals that in many case, in system identification with narrow band system estimation, the proposed adaptive filter has less computational complexities with faster convergence.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.8A
• /
• pp.836-846
• /
• 2007

Wireless Communication is playing a key role in implementing the ubiquitous society. However, due to the increasing wireless and mobile devices occupying the spectrum, the frequency resources are believed to become more and more limited. In order to deal with the problem, coexistence is considered to be a effective method to improve the efficiency of spectrum utilization between several different systems. Here, we utilize the UWB system to realize the coexistence, because it is an ultra wide band system which can co-exist with other narrow band systems. On the other hand, Cognitive Radio technology is an intelligent technology which can sense the spectrum environment and adaptively adjust the parameters for wireless transmission. In this paper, by using Cognitive UWB, the spectrum efficiency of the transmission channels is largely improved; Furthermore, the interference to other systems can be effectively avoided.

• The Journal of the Korea Contents Association
• /
• v.7 no.3
• /
• pp.42-49
• /
• 2007

This paper implements RFID(radio-frequency identification)System to which the system was apply SS(Spread Spectrum) method. The system designed by using the algorithm for microprocessor with PLL of the receiver, PN spread, modulation and demodulation of the transceiver, and transistor amplifier for the output of stabilized BPSK (Binary Phase Shift Keying) signal. furthermore, it reduced the interference of the signal by designing the micro-strip narrow banded patch antenna, which is convenient for printing and producing, and decreased the volume of filter size in the system. It is also designed for the lower powered system with the possible application to UHF band of $860\sim930MHz$ for the international standard frequency band, which is the quota share of RFID distribution system.

• Proceedings of the KOSOMBE Conference
• /
• v.1996 no.05
• /
• pp.240-242
• /
• 1996

In this paper, we proposed a method of a hearing aid suitable for the sensorineural hearing impaired. Generally as the sensorineural hearing impaired have narrow audible ranges between threshold and discomfortable level, the speech spectrum may easily go beyond their audible range. Therefore speech spectrum must be optimally amplified and compressed into the impaired's audible range. The level and frequency of input speech signal are varied continuously. So we have to make compensation input signal for frequency-gain loss of the impaired, specially in the frequency band which includes much information. The input sigaal is divided into short time block and spectrum within the block is calculated. The frequency-gain characteristic is determined using the calculated spectrum. The number of frequency band and the target gain which will be added input signal are estimated. The input signal within the block is processed by a single digital filter with the calculated frequency-gain characteristics. From the results of monosyllabic speech tests to evaluate the performance of the proposed algorithm, the scores of test were improved.