• Journal of Biomedical Engineering Research
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• v.6 no.1
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• pp.47-54
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• 1985

In this paper, clutter in ultrasound pulsed Doppler system is analyzed mathematically. And stationary canceler which reduce the clutter is designed. The operating characteristics of the stationary canceler is investigated in body (in vivo) by audio signal and spectrum analyzer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1109-1110
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.419-420
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• 2011

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.1
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• pp.1-9
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• 2009

In this paper, a 2.4 GHz doppler radar system consisting of a doppler radar sensor and a baseband module were designed to detect heart beat and respiration signal without direct skin contact. The doppler radar system emits RF signal of 2.4 GHz toward human chest, and then detects phase modulation of the reflected signal so as to investigate cardiopulmonary activities. The heartbeat and respiration signals acquired from I/Q channels of the doppler radar system are applied to the pre-processing circuit, the amplification circuit, and the offset circuit of the baseband module. The designed system was tested on mouse, rabbit and mankind, which have different range of heart rates and respiration signals, to evaluate detection accuracy of the system. ECG acquisition system and respiration transducer were used to generate the reference signal. In our experiments, a performance of detection were found to be high in the case that the subject stays still. In this paper, we confirmed that non-contact heart beat and respiration detection using the doppler radar has the possibility and limitation according to distance, cardiopulmonary activities, range of heart rates and respiration.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.612-618
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• 2019

In the unmanned vehicle industry, the market is exploding due to the rapid development of public and private demands along with the technological development of the 4th Industrial Revolution. In addition, unmanned mobiles are being used for communication services. In this paper, we analyzed the communication performance of unmanned aerial vehicle according to the characteristics of Doppler frequency. The Doppler frequency was calculated using the geometric model of the unmanned aerial vehicle, and the Doppler frequency of 10km, 30km, 300km, 1000km per hour and the BER performance by AWGN were measured by considering the unmanned high speed unmanned vehicle based on the position of the controller. The Doppler frequency model uses a Dent model and adds additive white Gaussian noise (AWGN) to check the bit errors of the transmitter and receiver. Low speed unmanned vehicles generally exhibited a BER performance of 0.2, while high speed unmanned vehicles generally exhibited a BER performance of 0.06. As the frequency band increases at the same speed, the BER performance increases, and when the speed increases in the same frequency band, the BER performance decreases. This is confirmed by the simulation results to predict theoretically predictable BER performance. In the frequency bands of 2.6 GHz, 5 GHz, and 28 GHz, the BER characteristics by Doppler frequency and the BER characteristics by controller function are verified. effect was confirmed.

• 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.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.477-483
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• 2018

Transcranial doppler is a non-invasive method that measures the blood flow velocity and the direction of cerebral blood vessels through the doppler principle. The pulsatility index is an index for measuring the transcranial doppler that reflects the distal vascular resistance and is used as an index for the presence and diffusion of cerebral small vessel diseases. The purpose of this study was to evaluate the risk factors affecting the basilar artery pulsatility index in ischemic stroke patients. From January 2014 to May 2015, 422 patients were selected by measuring the transcranial doppler pulsatility index, considering their basilar artery pulsatility index. Univariate analysis was performed using the basilar artery pulsatility index as a dependent variable. Multiple regression analysis was performed considering the factors affecting the pulsatility index as variables. Univariate analysis revealed age, presence of hypertension, presence of diabetes mellitus, presence of hyperlipidemia, and hematocrit (P<0.1) as factors. Multiple regression analysis showed statistically significant results with age (P<0.001), presence of diabetes (P=0.004), and presence of hyperlipidemia (P=0.041). The risk factors affecting the basilar artery pulsatility index of transcranial doppler were age, diabetes, and hyperlipidemia. Further research will be needed to increase the cerebral pulsatility index as a surrogate marker of the elderly, diabetes, and hyperlipidemia.

• Journal of Yeungnam Medical Science
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• v.14 no.1
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• pp.77-84
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• 1997

We measured the blood flow velocity of the anterior cerebral artery via anterior fontanelle approach of fifty five preterm neonates with duplex Doppler sonography and analyzed the waveform and calculated pulsatility index, resistive index. Intracranial velocities and pulsatility indexes were increased with increasing gestational age, birth weight, and age of the neonate, but resistive indices decreased. In sick babies, characteristic resistive index increment were seen in patients with intraventricular hemorrhage, but no statistical difference was seen in patients with respiratory distress syndrome. Our results suggest that duplex Doppler sonography is a useful noninvasive means of monitoring cerebrohemodynamics in normal preterm neonates and flow change of sick babies.

• ETRI Journal
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• v.22 no.4
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• pp.32-39
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• 2000

In low earth orbit (LEO) satellite communication systems, more severe phase distortion due to Doppler shift is frequently detected in the received signal than in cases of geostationary earth orbit (GEO) satellite systems or terrestrial mobile systems. Therefore, an estimation of Doppler shift would be one of the most important factors to enhance performance of LEO satellite communication system. In this paper, a new adaptive Doppler compensation scheme using location information of a user terminal and satellite, as well as a weighting factor for the reduction of prediction error is proposed. The prediction performance of the proposed scheme is simulated in terms of the prediction accuracy and the cumulative density function of the prediction error, with considering the offset variation range of the initial input parameters in LEO satellite system. The simulation results showed that the proposed adaptive compensation algorithm has the better performance accuracy than Ali's method. From the simulation results, it is concluded the adaptive compensation algorithm is the most applicable method that can be applied to LEO satellite systems of a range of altitude between 1,000 km and 2,000 km for the general error tolerance level, M = 250 Hz.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.443-446
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• 2005

This paper presents the results of the design and implementation of the airborne pulse doppler radar signal processor using high multi-DSP for the multi-function radar capability such as short-range, midium-range, and long-range depending on the mission of the vehicle. Particularly, the radar signal processor is developed using two DSP boards in parallel for the various radar signal processing algorithm. The key algorithms include LFM chirp waveform-based pulse compression, MTI clutter filter, MTD processor, adaptive CFAR, and clutter map. Especially airborne moving clutter Doppler spectrum compensation algorithm such as TACCAR is implemented for the multi-mode airborne radar system. The test results shows the good Doppler spectral separation for the clutter and the moving target in the flight test environment using helicopter