• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.700-702
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• 2016

The Doppler Radar that mounted on Electro Optical Tracking System has been operated to measure range and velocity during the initial mission of space launch vehicle at Naro space center. In this paper, we mentioned configuration of MFCW(Multi frequency Continuous Wave) and FMCW(Frequency Modulation Continuous Wave) Doppler Radar on Electro Optical Tracking System and described method of range measurement.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1575-1577
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• 2002

In this research we propose a method far rain rate estimation by using Doppler spectrum's data of wind profiler. The Doppler spectrum is used to calculate the wind velocity and wind direction. But in this research uses the parameters from Doppler spectrum, it calculates the rain rate. The rain rate estimation in this method will be compared to the obtained rain rate from the surface rain gauge. Two equipments are installed in the same area. The correlation coefficient between rain rate measuring method is 0.65.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.815-821
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• 2012

A CW Doppler radar can measure radial velocity of an object. It detects a Doppler frequency shift that is proportioned to radial velocity of a moving object. To detect a Doppler frequency shift, FFT(Fast Fourier Transform) is conducted. In this process, the time domain received signal is transformed to a frequency domain. A number of FFT affects not only the time resolution but also signal to noise ratio of received signal. So finally it is related with a radial velocity accuracy. Therefore in this paper, it is described the relation of time resolution and the radial velocity accuracy.

• Journal of Acupuncture Research
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• v.26 no.2
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• pp.49-58
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• 2009

Objectives : The aim of this study was to investigate whether Doppler ultrasound device is applicable for the evaluation of facial palsy patients. Methods : A total of 25 patients participated in the first assessment and 22 of them finished a follow-up assessment one week later. An assessment comprised of a Minimax-Doppler-K device examination on bilateral acupoints $ST_5$, $SI_{19}$, $ST_2$, and $BL_1$, House-Brackmann grading, and subjective symptom questionnaire. Measurement reliability was assessed and clinically meaningful variations of Doppler measurement values were explored. Results : Doppler ultrasound examination revealed a significant difference of some measurement values between values of the symptom side and the contralateral side, between groups of severe paralysis and moderate paralysis, and between groups of short duration(0-3 weeks) and long duration (3 weeks-5 months) by non-parametric analyses (p<0.05). Several re-examination values showed a significant correlation with the first examination values by Spearman's correlation tests (p<0.05). Conclusions : This study revealed several possibilities for the clinical application of this device. Further validity tests and device improvements for a user's convenience would be helpful for its practical application.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.3 s.52
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• pp.259-263
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• 2005

The aim of the present study is to evaluate relationship between UV-induced MED and perfusion value assessed by Laser Doppler Perfusion Imager. In this study, A increasing linear relationship is seen between perfusion and dose (p<0.05). The dose-response curve show a steep slope in the case of lower MED values group after MED point, For higher MED group, increase with a gentle slope.

• Atmosphere
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• v.32 no.2
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• pp.163-178
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• 2022

This study aims to evaluate the accuracy of retrieved horizontal winds with different quality control methods from three Doppler lidars deployed over the complex terrain during the PyeongChang 2018 Olympic and Paralympic games. To retrieve the accurate wind profile, this study also proposes two quality control methods to distinguish between meteorological signals and noises in the Doppler velocity field, which can be broadly applied to different Doppler lidars. We evaluated the accuracy of retrieved winds with the wind measurements from the nearby or collocated rawinsondes. The retrieved wind speed and direction show a good agreement with rawinsonde with a correlation coefficient larger than 0.9. This study minimized the sampling error in the wind evaluation and estimation, and found that the accuracy of retrieved winds can reach ~0.6 m s^-1 and 3° in the quasi-homogeneous wind condition. We expect that the retrieved horizontal winds can be used in the high-resolution analysis of the horizontal winds and provide an accurate wind profile for model evaluation or data assimilation purposes.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.3-12
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• 2003

Ultrasonic pulsed Doppler velocimetry has become a standard international method of classifying carotid disease. Because the measured angle adjusted velocity increases as the Doppler angle increases, examinations should be performed at a convenient standard Doppler examination angle. An angle of 60 degrees is achievable throughout most examinations. Multiple Doppler viewing angles allow the acquisition of velocity vectors during the cardiac cycle, revealing the complex velocity patterns. Ultrasonic velocimetry (whether Doppler or time domain) is based on changes in the phase of the ultrasound echo. Other examinations can be done based on the echo phase. Slow motions of organs such as the brain can be used to monitor changes in edema. Measurements of tissue strain due to the pulsatile filling of the arterioles. This plethysmographic imaging method can display differences in tissue perfusion because of different tissue types and changes in autonomic activity.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.310-318
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• 2016

This study deals with a method to localize a noise source occuring in a marine vehicle in a 3D environment. Even when access to the noise source is limited for a marine vehicle, such as a ship or a submarine in operation, the signal received on a hydrophone located elsewhere contains Doppler effected noise by moving relatively. This study suggests noise localization algorithm in 3D based on Doppler effect by moving marine vehicle. Using a known source mounted on the vehicle, the noise source was estimated by reducing the range of Doppler center and closest point of approach via the least square method. The algorithm was verified through various simulations and it was shown that the noise could be localized in 3D based on Doppler effect by employing two fixed hydrophones located at the vehicle's exterior points and a known reference signal generator located somewhere on the vehicle.

• 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.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.60-63
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• 1999

Transcranial Doppler(TCD) is an important diagnostic tool for evaluating the patients with stroke. It has some advantages and unique role when compared with other neuroimaging modalities. Recent development of transcranial color-coded Doppler(TCD) improves the limitation and pitfalls of TCD. The current indications of TCD are as follows: 1. Screening and evaluation of the intracranial major vessels 2. early detection and follow-up of vasospasm due to SAH 3. emboli detection (high-imtensity transient signals, HITs) 4. dignosis and follow-up of subclavian steal 5. evaluation of intracranial collaterals when the extracranial ICA has severe stenosis or occlusion 6. evaluation of cerebral perfusion pressure (intracranial pressure) 7. evaluation of arteriovenous malformation 8. diagnosis and follow-up of arterial dissenction 9. diagnosis and follow-up of venous sinus thrombosis (experimental).