• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.737-747
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• 2013

A 3-D surveillance radar is a pulsed-doppler radar to provide various target information, such as range, doppler and angle by performing TWS. This paper introduces HW/SW architecture of radar signal processing board to process in real-time using high-speed multiple DSP(Digital Signal Processor) based on COTS. Moreover, we introduced a implemented algorithm consisted of clutter map creation/renewal, FIR(Finite Impulse Response) filter for rejection of zero velocity components, doppler filter, hybrid CFAR and finally presented computational burden of each algorithm by performing operational test using a beacon.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.143-152
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• 1998

In this paper, we present the performances of a Doppler system using single channel RF(Radio Frequency) sampling. This technique consists of undersampling the ultrasonic blood backscattered RF signal on a single channel. Conventional undersampling method in Doppler imaging system have to use a minimum of two identical parallel demodulation channels to reconstruct the multigate analytic Doppler signal. However, this system suffers from hardware complexity and problem of unbalance(gain and phase) between the channels. In order to reduce these problems, we have realized a multigate pulsed Doppler system using undersampling on a single channel, It requires sampling frequency at $4f_o$(where $f_o$ is the center frequency of the transducer) and 12bits A/D converter. The proposed " single-Channel RF Sampling" method aims to decrease the required sampling frequency proportionally to $4f_o$/(2k+1). To show the influence of the factor k on the measurements, we have compared the velocity profiles obtained in vitro and in vivo for different intersequence delays time (k=0 to 10). We have used a 4MHz center frequency transducer and a Phantom Doppler system with a laminar stationary flow. The axial and volumetric velocity profiles in the vessel have been computed according to factor k and have been compared. The influence of the angle between the ultrasonic beam and the flow axis direction, and the fluid viscosity on the velocity profiles obtained for different values of k factor is presented. For experiment in vivo on the carotid, we have used a data acquisition system with a sampling frequency of 20MHz and a dynamic range of 12bits. We have compared the axial velocity profiles in systole and diastole phase obtained for single channel RF sampling factor.ng factor.

• Korean Journal of Head & Neck Oncology
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• v.17 no.1
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• pp.19-25
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• 2001

Objectives: The clinical efficacy of the color and pulsed Doppler ultrasound with spectral waveform analysis for differentiation of malignant from benign cervical lymphadenopathy was prospectively evaluated in cervical lymphadenopathy. Materials and Methods: Color and pulsed Doppler ultrasound examination was prospectively performed in 32 cervical lymph nodes in 28 patients. These 10 nodes from 10 patients were malignant and 22 nodes from 18 patients were benign, proved by operation, biopsy, and follow-up examination. Another 12 lymph nodes from 12 normal volunteers were evaluated as control group. The peak systolic velocity (PSV), minimal diastolic velocity (MDV) , and resistive indexes (RI) of arterial flows within the 32 lymph nodes were assessed to differentiate the malignant from benign nodes with pulsed Doppler ultrasonography. The results were qualitified with one-way ANOVA and Bonferroni method of multiple comparison. Results: The mean values of PSV of malignant, benign, and control nodes were 38.2(10.1-134)cm/sec, 23.3(9-38.5) cm/sec and 11.8(6.7-18.1) cm/sec, respectively. The mean values of MDV of them were 0.9(-7.5-10.7)cm/sec, 9.7(2.9-18.6)cm/sec and 6.5(3.7-9.3)cm/sec, respectively. However, there was no statistical significance in differentiation of malignant from benign nodes with PSV and MDV. The mean values of RI of malignant, benign, and control nodes were 0.99(0.80-1.30), 0.59(0.46-0.77) and 0.45(0.38-0.50), respectively. RI value of 0.8 is suggestive value for discrimination of malignant from benign lymphadenopathy during examination of color Doppler ultrasound of cervical lymphadenopathy. Conclusion: Color and pulsed Doppler ultrasound examination with spectral waveform analysis may be quite helpful in the differentiation between benign and malignant alterations of cervical lymph nodes.