• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2292-2297
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• 1999

Some observed weather spectra show that nearly 25% of weather spectra are seriously skewed and can not be considered to be symmetric. However, the conventional pulse pair method was derived and has been evaluated under the assumption that the weather spectrum is symmetric and narrow. This means that the conventional pulse pair method may need reevaluation. Therefore, this paper analyzed the bias errors of pulse pair estimates in the skewed spectra. The bias errors of pulse pair mean estimates are more serious comparing with the pulse pair width estimates. In this paper, the poly-pulse pair method is suggested to reduce these bias errors of mean estimates. It was shown that the mean bias errors can be reduced remarkably using the newly suggested poly-pulse pair method.

• Journal of Veterinary Clinics
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• v.32 no.2
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• pp.162-167
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• 2015

Tei-index has been reported as one of reliable echocardiographic factors for evaluating cardiac function in human and small animals. In this study, Tei-index were measured and evaluated with other echocardiographic parameters in normal thirteen beagle dogs and thirty-one dogs with mitral valve degeneration. Normal range of Tei index with tissue Doppler obtained at septum and left ventricular free wall was $0.58{\pm}0.07$ and $0.60{\pm}0.07$, respectively. The values between septum and left ventricular free wall did not show significant difference. Tissue Doppler derived tei index showed better reproducibility and significantly lower values than the results obtained by pulsed wave Doppler. Tei index obtained in either method increased with the progression of clinical signs. Therefore, the increase of Tei index in dogs with mitral regurgitation is thought to be an useful factor reflecting left ventricular dysfunction.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.5
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• pp.95-104
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• 2019

In this paper, we propose a method to design a generalized sinusoidal frequency modulated(GSFM) pulse that is robust to reverberation environment. GSFM pulses are a generalized form of SFM(Sinusoidal frequency modulated) pulses, which have the advantage of having a thumbtack ambiguity function with excellent range and Doppler resolution. However, the periodicity disappears during the generalization process, therefore, the detection performance is reduced in reverberation environment compared to SFM pulse with comb spectrum. In this paper, the trade-off relationship between the reverberation suppression performance of the SFM pulse and the range resolution performance of the GSFM pulse is analyzed by appropriately changing the parameter ${\rho}$ of the GSFM pulse. In order to verify the performance of the proposed GSFM pulse, the simulation was performed and it was confirmed that the proposed GSFM pulse has excellent distance resolution while detecting the slow Doppler target.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.516-519
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• 2001

To diagnose a patient's blood vessel disease, apoplexy, hypertension, arteriosclerosis, the blood velocity is very important. Determining the blood velocity methods using ultrasound are Continuous Doppler System and Pulse Doppler System. In using the Pulse Doppler System, we can obtain the position of blood velocity. But it is more complex hardware than Continuous Doppler System and it has low SNR(signal-noise ratio). So in this study, to obtain a believable information we use the Continuous Pulse Doppler System. Thus system have analog part and digital part. In analog part is composed of ultrasound generating part, the amplifying part to amplify the received signal from ultrasound sensor, the demodulation part to detect blood velocity and the filtering part to remove the noise. In digital part is composed of the A/D conversion part, digital signal processing part, and the communication part to communicate the PC. In this study to implement efficient ultrasound blood velocity measurement system, we can get the patient's blood velocity information in realtime. Thus, It is a useful in the accurate diagnosis with C.T(computered tomography), M.R.I(magnetic resonance imaging).

• Journal of IKEEE
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• v.22 no.3
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• pp.624-629
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• 2018

Classification of moving targets in Pulse Doppler Radar(PDR) for surveillance and reconnaissance purposes is generally carried out based on listening and training experience of Doppler audio signals by radar operator. In this paper, we proposed the automatic classification method to identify the class of moving target with Doppler audio signals using the Mel Frequency Cepstral Coefficients(MFCC) and the Hidden Markov Model(HMM) algorithm which are widely used in speech recognition and the classification performance was analyzed and verified by simulations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.33-40
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• 1984

In the conventional pulsed doppler system, gated CW is used to excite a ultrasonic transducer so that a group of linear RF amplifiers are required to excite a ultrasonic array transducer in the scanning pulsed doppler system. A pulsed doppler system without linear high voltage RF amplifiers, which excites the transducer impulsively, is studied theoretically and experimentally. In this paper, an experimental 8-channel pulsed doppler system is implemented, which uses quadrature defection to detect the direction of motion and can compensate the attenuation effect. The designed pulsed doppler system shows the possibility of real time multichannel doppler flow meter.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.173-180
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• 2006

An airborne radar is an essential aviation electronic system of the aircraft to perform various missions in all weather environments. This paper presents the design, development, and test results of the multi-mode pulsed Doppler radar system test model for helicopter-borne flight test. This radar system consists of 4 LRU units, which include ANTU(Antenna Unit), TRU(Tx Rx Unit), RSDU(Radar Signal & Data Processing Unit) and DISU(Display Unit). The developed technologies include the TACCAR processor, planar array antenna, TWTA transmitter, coherent I/Q detector, digital pulse compression, DSP based Doppler FFT filtering, adaptive CFAR, IMU, and tracking capability. The design performance of the developed radar system is verified through various helicopter-borne field tests including MTD (Moving Target Detector) capability for the Doppler compensation due to the moving platform motion.

• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.791-800
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• 2020

Ultrasonography is widely used to evaluate the function of fetal heart, but due to the subjective nature of the test, there are differences in measurement methods for each examiner, and especially the myocardial performance index has no reference index to date. Therefore, in this study, we wanted to analyze pulse Doppler waveforms of normal fetuses and develop an automatic measurement program to make objective measurements. One hundred and thirty-three pregnant women who visited the hospital for prenatal examinations were studied, myocardial performance index was measured after acquiring a pulse doppler image of the left ventricle. As a result, the early, mid and late pregnancy myocardial performance index, measured by the automatic measurement program conducted in this study, was found to increase as pregnancy continued.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.17-24
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• 1999

• Proceedings of the Acoustical Society of Korea Conference
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• 1996.06a
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• pp.63-63
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• 1996