• Journal of Information Processing Systems
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• v.15 no.4
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• pp.820-832
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• 2019

Estimation of accurate blood volume flow in ultrasound Doppler blood flow spectrograms is extremely important for clinical diagnostic purposes. Blood volume flow measurements require the assessment of both the velocity distribution and the cross-sectional area of the vessel. Unfortunately, the existing volume flow estimation algorithms by ultrasound lack the velocity space distribution information in cross-sections of a vessel and have the problems of low accuracy and poor stability. In this paper, a new robust ultrasound volume flow estimation method based on multigate (RMG) is proposed and the multigate technology provides detail information on the local velocity distribution. In this method, an accurate double iterative flow velocity estimation algorithm (DIV) is used to estimate the mean velocity and it has been tested on in vivo data from carotid. The results from experiments indicate a mean standard deviation of less than 6% in flow velocities when estimated for a range of SNR levels. The RMG method is validated in a custom-designed experimental setup, Doppler phantom and imitation blood flow control system. In vitro experimental results show that the mean error of the RMG algorithm is 4.81%. Low errors in blood volume flow estimation make the prospect of using the RMG algorithm for real-time blood volume flow estimation possible.

• Journal of ILASS-Korea
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• v.6 no.1
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• pp.18-24
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• 2001

Liquid fossil fuel contaminated by water can cause trouble in the combustion processes and affect the endurance of a combustion system. Using an optical sensor to monitor the water content instantaneously in a fuel pipeline is an effective means of controlling the fuel quality in a combustion system. In two component liquid flows of oil and water, the flow pattern and characteristics of water droplets are changed with various flow conditions. Additionally, the light scattering of the optical sensor measuring the water content is also dependent on the flow patterns and droplet characteristics. Therefore, it is important to investigate the detailed behavior of water droplets in the pipeline of the fuel transportation system. In this study, the flow patterns and characteristics of water droplets in the turbulent pipe flow of two component liquids of gasoline and water were investigated using optical measurements. The dispersion of water droplets in the gasoline flow was visualized, and the size and velocity distributions of water droplets were simultaneously measured by the phase Doppler technique. The Reynolds number of the gasoline pipe flow varied in the range of $4{\times}10^{4}\;to\;1{\times}10^{3}$, and the water content varied in the range of 50 ppm to 300 ppm. The water droplets were spherical and dispersed homogeneously in all variables of this experiment. The velocity of water droplets was not dependent on the droplet size and the mean velocity of droplets was equal to that of the gasoline flow. The mean diameter of water droplets decreased and the number density increased with the Reynolds number of the gasoline flow.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.997-1004
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• 2007

High resolution synthetic aperture radar image could be sensitive to the various parameters of the payload, platform, and ground system. In this paper, a parameter based SAR simulator is presented for two-dimensional image formation and image quality analysis. Functional modules are implemented by Matalb code and GUI for the flexibility and expandability. Main function of this simulator includes the SAR input signal generation, range-doppler algorithm(RDA) based SAR image formation, and the SAR image quality analysis which is relevant to the SAR system design parameters. This simulator can effectively be used for the SAR image quality performance evaluation, which can be applicable to the airborne as well as spaceborne SAR system design and analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.3
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• pp.528-535
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• 2011

In this paper, a compact doppler sensor with oscillator type active antenna operating at 2.4GHz frequency band is proposed to measure the distance to a moving object. The oscillation frequency is shifted depending on approaching of the object, and a detection circuit discriminates the frequency deviation. The active antenna has been designed and simulated. The prototype fabricated has a small circular disk type of diameter 30mm and height 4.2mm. As for antenna performance, broadside radiation pattern with beamwidth of $120^{\circ}$ and oscillation frequency of 2.35GHz has been measured. Test results as a range sensor shows that signal voltage of about 240mV has been obtained for conducting plate moving 1 meter away from the sensor. And, signal voltage has been linearly increased to the ground from 5m height by free-falling the sensor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.8
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• pp.1090-1098
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• 2018

Many short range weather radars with the low elevation search capability are needed for analysis and prediction of unusual weather changes or rainfall phenomena which occurs regionally. However, due to the characteristics of low elevation electromagnetic wave beam, it is highly probable that the received weather signals of these radars are seriously contaminated by the ground clutter. Therefore, the filter removing low Doppler frequency band is generally used to mitigate this problem. However, the phase noise in a radar system may limit the removal of the strong clutter and this may cause serious problems in estimating weather parameters because of the remaining clutter. Therefore, in this paper, the characteristics of phase noise in a radar system are investigated and the effects of the system phase noise are analyzed in the improvement of signal to clutter ratio for the strong clutter environment such as a short and low-elevated weather radar.

• 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.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.2
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• pp.71-79
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• 2019

Geolocation accuracy is one of the important factors in utilizing all weather available SAR satellite imagery. In this study, an error budget analysis was performed on key variables affecting on geolocation accuracy by generating KOMPSAT-5 simulation data. To perform the analysis, a Range-Doppler model was applied as a geometric model of the SAR imagery. The results show that the geolocation errors in satellite position and velocity are linearly related to the biases in the azimuth and range direction. With 0.03cm/s satellite velocity biases, the simulated errors were up to 0.054 pixels and 0.0047 pixels in the azimuth and range direction, and it implies that the geolocation accuracy is sensitive in the azimuth direction. Moreover, while the clock drift causes a geolocation error in the azimuth direction, a signal delay causes in the range direction. Monte-Carlo simulation analysis was performed to analyze the influence of multiple geometric error sources, and the simulated error was up to 3.02 pixels in the azimuth direction.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.501-504
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• 2000

The classical image reconstruction for stripmap SAR is the range-Doppler imaging. However, when the spotlight SAR system was envisioned, range-Bowler imaging fumed out to fail rapidly in this SAR imaging modality. What is referred to as polar format processing, which is based on the plane wave approximation, was introduced for imaging from spotlight SAR data. This paper has been studied for the raw data processing schemes in the spotlight-mode synthetic aperture radar. we apply the wavefront reconstruction scheme that does not utilize the approximation in spotlight-mode SAR imaging modelity, and compare the performance of target imaging with the polar format inversion scheme.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.270-274
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• 2008

The microwave sensor in which the sensitivity was excellent and a structure is simple was developed and it manufactured. And the sensing range that uses the developed product was confirmed. When the developed microwave sensor was set up in the ceiling of a building, we confirmed that the amplitude of the sensitive area increased as the tilting angle was enlarged. The sensitive area became a greatest in case the tilting angle was 65 degree. According to the height of a ceiling, because the sensing range is determined, in case of using in the building in which the height of a ceiling is enough secured it is determined to secure the more wide sensitive area. Moreover, the configuration of the circuit having the simple structure makes the miniaturization of a product, and the light weight possible. It is considered to have the price competitive power which it reduces the manufacturing cost, is sufficient.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.250-253
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• 2024

This paper proposes a low-power waveform for a long-range air-to-air data link. In the case of an air-to-air data link, data communication is performed in the air and high Doppler shift may occur depending on the flight speed, so a waveform based on the non-coherent method is suitable. In addition, since it is mounted on an aircraft, it must have low power characteristics. This paper proposes a waveform that combines a modulation technique based on frequency modulation and pulse position modulation that can turn on/off the transmission signal. As a result of the performance analysis, it was shown that the performance was suitable for air-to-air operation while showing low power characteristics.