• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.700-702
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• 2016

나로우주센터에서는 우주발사체의 비행임무 초기구간 동안에 발사체의 거리 및 속도정보를 획득하기 위해서 광학추적장비에 거리측정 도플러 레이더를 탑재하여 운용하고 있다. 본 논문은 광학추적장비의 MFCW(Multi Frequency Continuous Wave)방식과 FMCW(Frequency Modulation Continuous Wave)방식 도플러 레이더 구성과 거리측정 방법을 기술하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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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.

• 한국전자파학회논문지
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• 제23권7호
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• pp.815-821
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• 2012

CW 도플러 레이더는 움직이는 물체의 속도에 비례하는 도플러 주파수 편이를 검출함으로써 속도를 계측한다. 도플러 주파수 편이를 검출하기 위해서 시간영역에서 획득한 수신 신호를 주파수 영역으로 변환하기 위한 FFT(Fast Fourier Transform)를 수행한다. 이때 FFT 개수에 의해 도플러 레이더의 시각 분해능이 달라진다. 또한, FFT 개수는 수신 신호의 신호 대 잡음비에도 영향을 미치므로, 결국 시선 속도의 정확도와도 관련 있다. 따라서 본 논문에서는 FFT 개수에 따라 달라지는 시각 분해능과 시선 속도 정확도의 관계를 제시하였다.

• Journal of Acupuncture Research
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• 제26권2호
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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.

• 대한화장품학회지
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• 제31권3호
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• pp.259-263
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• 2005

혈류량은 자외선 조사량 증가에 비례하여 증가되는 양상을 보였다. 홍반을 유발하는데 필요한 자외선량(MED)의 차이가 혈류량의 변화와 어떠한 관계가 있는지를 알아본 실험에서, MED가 30 mJ로 비교적 낮았던 피험자들의 경우, 혈류량은 MED를 지나서 급격하게 증가되는 양상을 관찰하였으나 30 mJ 이상에서 MED가 관찰되었던 피험자들의 경우에는 자외선 조사에 따른 혈류량의 변화가 급격한 변화 없이 계속 완만하게 증가되는 양상을 보였다.

• 대기
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• 제32권2호
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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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• 제1권1호
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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.

• 한국음향학회지
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• 제35권4호
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• pp.310-318
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• 2016

본 연구는 해상 운항체에서 발생하는 소음원의 위치를 3차원적으로 추정하는 방법에 대해 다루었다. 해상 운항체인 선박이나 잠수함의 내부에 존재하는 소음원과 같이 근접이 어려운 경우라도 상대적으로 이동한다면 외부의 수중청음기에 수신된 신호는 도플러 효과가 발생한다. 본 연구에서는 이동 물체에 의한 도플러 효과를 바탕으로 소음원의 3차원 위치 추정 알고리즘을 제안하였다. 해상 운항체의 알고 있는 위치에 추가의 음원을 설치하여 예상되는 도플러 중심의 범위와 최단 접근점의 범위를 점차 줄여가며 최소자승법을 통하여 내부 소음원의 위치를 추정하였다. 알고리즘을 통해 계산한 값과 이론값을 비교하여 효용성을 입증하였으며, 수치시험을 통해 고정된 두 개의 외부 수중청음기와 음원 역할을 하는 수중체에 고정시킨 한 개의 신호발생기로 도플러 효과를 기반으로한 소음원의 3차원 위치 추정이 가능함을 증명하였다.

• 대한의용생체공학회:의공학회지
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• 제19권2호
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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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• 제1권1호
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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).