• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.61-66
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• 2005

In this paper, we implemented a impulse generator, the one of the part in UWB(Ultra Wide Band) system using step recovery diode(SRD) and gain-switced semiconductor laser. The impulse generator was consisted of four stages; The first stage used SRD to generate the first impulse for gain switching. The second stage controled current for the suitable gain switching condition. The third was the second impulse generator to generate gaussian pulse. For gain switching, the first impulse was applied to semiconductor laser. In the last stage the gain switched impulse was converted into mono-gaussian pulse. The measured mono-gaussian pulse was 360 psec pulse-width and $-70mV \~ +50mV$ amplitude in time domain. In frequency domain its magnitude and bandwidth was, respectively, -41dBm and 3.6GHz. Accordingly, the impulse generator that we suggested was suitable for UWB systems.

• Journal of the Optical Society of Korea
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• v.7 no.4
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• pp.258-263
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• 2003

Simple algebraic expressions are derived to approximate the optimal input RMS pulse width and the resulting output RMS pulse width in single-mode fibers. The results are compared with the previously published methods and with numerical results by the split-step Fourier method. In addition, for a transform-limited Gaussian input pulse, it is shown that there is no optimum input pulse width to minimize the output spectrum width. Finally, with fiber nonlinearity, it is shown mathematically that there is not an optimum input pulse width to minimize the product,${\sigma}_t{\sigma}_{\omega}$, which is inversely proportional to the transmission capacity of WDM systems.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.250-253
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• 2003

In this paper, a characteristics and points of Guassian pulse using UWB system is analyzed, the TDMG pulse is proposed that originated ultra wide band signal without pulse width reduction. It is showed that TDMG pulse character compare with Gaussian pulse through computer simulation. And it is verified that decreased a interference of other communication systems

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.223-226
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• 2004

This paper analyzes the accuracy of free space path loss and matched filter gain approximated by using a passband rectangular pulse for ultra wideband (UWB) radio systems. The example causal signal, a modulated Gaussian pulse with the same center frequency and frequency bandwidth of the passband rectangular pulse, is used to consider the accuracy. The path loss and matched filter gain of the modulated Gaussian pulse are simulated for the reference results. The UWB free space path loss is shown and is compared with that obtained from simulation and Friis' transmission formula. The UWB matched filter gain is shown and compared with simulation results. From the results, we can see that the UWB path loss formula is more accurate than the Friis' transmission formula. The results from the UWB free space path loss and matched filter gain formulas agree with the simulation. Then, these free space path loss and matched filter gain formulas approximated by using a passband rectangular pulse are appropriate for UWB system.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.185-194
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• 2014

One in every 10 persons suffer from chronic gastritis in Korea. Endoscopy is most commonly used to diagnose the chronic gastritis. Endoscopic diagnosis is precise but it is accompanied with pain and high cost. According to pulse diagnosis in Traditional East Asian Medicine, health problems in stomach can be diagnosed with radial pulse signals in 'Guan' location in the right wrist, which are non-invasive and cost-effective. In this study, we developed a classification model of chronic gastritis using pulse signals in right 'Guan' location. We used both linear discrimination method and logistic regression model with respect to pulse features obtained with a peak-valley detection algorithm and a Gaussian model. As a result, we obtained sensitivity ranged between 77%~89% and specificity ranged between 72%~83% depending on classification models and feature extraction methods, and the average classification rates were approximately 80%, irrespective of the models. Specifically, the Gaussian model were featured by superior sensitivities (89.1% and 87.5%) while the peak-valley detection method showed superior specificities (82.8% and 81.3%), and the average classification rate (sensitivity + specificity) of the Gaussian model was 80.9% which was 1.2% ahead of the peak-valley method. In conclusion, we obtained a reliable classification model for the chronic gastritis based on the radial pulse feature extraction algorithms, where the Gaussian model was featured by outperformed sensitivity and the peak-valley method was featured by outperformed specificity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1121-1126
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• 2003

In this paper we show impulse generator which is important component in UWB communication. There is two steps to generate monocycle impulse. In first step, Gaussian pulse was made by operation of transistor switching and operation time of transistor switching. The second step the high pass filter change from Gaussian to Monocycle impulse. The result of this impulse generator is impulse whose pulse width is 0,9 ns in time domain and amplitude is +/-250 ㎷.

• Journal of Communications and Networks
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• v.10 no.4
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• pp.451-454
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• 2008

Ultra-wideband (UWB) radios have attracted great interest for their potential application in short-range high-data-rate wireless communications. High received signal to noise ratio and compliance with the Federal Communications Commissions (FCC) spectral mask call for judicious design of UWB pulse shapers. In this paper, even and odd order derivatives of Gaussian pulse are used respectively as base waveforms to produce two synthesized pulses. Our method can realize high efficiency of spectral utilization in terms of normalized effective signal power (NESP). The waveform design problem can be converted into linear programming problem, which can be efficiently solved. The waveform based on even order derivatives is orthogonal to the one based on odd order derivatives.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.5
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• pp.384-394
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• 1996

The propagation properties of square and Gaussian pulse signals on the microstrip line are investigated by using proper conventional models to meet the frequency range of a pulse, accuracy, and geometrical requirements of the microstrip line. Numerical integration technique which has its accuracy and is easily simulated, is used to obtain the time domain response of pulse signals. The dispersion of pulse signals is analyzed regarding to the relative permittivity $\varepsilon_r$, substrate height h, strip width w of the microstrip line and pulse width $\tau$ of signal pulse. The simulation results show that small relative permittivity and small rationale of w/h are advantageous for the dispersion of the pulse signals, and that pulse signals with small bandwidth cause smaller dispersion. The results of this paper are compatible to the trade-off determination of relative permittivity, substrate height, strip width and pulse width of signal pulse when a design of MIC and MMIC is necessary.

• Korean Journal of Optics and Photonics
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• v.21 no.6
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• pp.254-258
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• 2010

We investigate an optical technique for beam shaping and optical amplification of a pulsed laser diode without variation of its original properties, such as repetition rate and pulse duration. The horizontal and longitudinal sizes of the pulsed laser diode are 300 and $2{\mu}m$, respectively, and its output power is $1.1mW/cm^2$. The multimodal and elliptical pulse shape of the laser diode is converted to the single-modal and Gaussian pulse shape by using a lensed optical fiber. Since the single-modal lensed fiber coupling from the multimodal pulsed laser diode degrades the output power severely, the output power of the pulsed laser diode is dramatically enhanced by using an optical amplification method based on master oscillated power amplification (MOPA). The pulse qualities of the laser diode are not changed after amplifying the pulse power and the output power was finally measured to be $29mW/cm^2$.

• Journal of Communications and Networks
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• v.16 no.1
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• pp.92-97
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• 2014

A novel method for extracting frequency slippage signal from radar full pulse sequence is presented. For the radar full pulse sequence received by radar interception receiver, radio frequency (RF) and time of arrival (TOA) of all pulses constitute a two-dimensional information sequence. In a complex and intensive electromagnetic environment, the TOA of pulses is distributed unevenly, randomly, and in a nonstationary manner, preventing existing methods from directly analyzing such time series and effectively extracting certain signal features. This work applies Gaussian noise insertion and structure function to the TOA-RF information sequence respectively such that the equalization of time intervals and correlation processing are accomplished. The components with different frequencies in structure function series are separated using empirical mode decomposition. Additionally, a chaos detection model based on the Duffing equation is introduced to determine the useful component and extract the changing features of RF. Experimental results indicate that the proposed methodology can successfully extract the slippage signal effectively in the case that multiple radar pulse sequences overlap.