• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.153-156
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• 1994

An in vitro steady flow experiment was performed in order to test the accuracy of velocity measurement obtained through a pulsed Doppler echocardiography. A flow phantom was designed for the use in a wide velocity range at a given flow rate. The results showed that the pulsed Doppler velocity measurement obtained in this flow phantom is accurate at low flow rates. However, ultrasound velocity measurement should be performed under a careful considerations of PRF and Doppler gain settings, especially at higher flow rates.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.47-54
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• 1999

The Doppler in neurosonologic examination could be applied to blood flow to determine its movement, the direction of its movement, and how fast it is. Indicies of the Doppler study denoted velocity, direction, and amount of RBC in the examined vessel. Systolic. diastolic, and mean blood flow velocities represent velocity of RBCs in a sample volume. Blood flow direction to the probe means direction of RBC to the probe. Size of amplitude displays toe amount of the RBCs passing the sample volume. Spectral broadening means presence of turbelence. The RBC movements and hemodynamics at the examined vessels can be estimated by analysis of Doppler indicies The formation and meaning of each of neurosonologic Doppler study is described in the present review.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.83-91
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• 2024

The purpose of this study was to determine the doppler fluid effects of carbonated water (CBW) in a bi-directional flow phantom model. A bi-directional flow phantom model was chosen to realize arterial and venous flow, and the structure of the inner and outer tanks allowed for fluid circulation and also made the size of the phantom small. Carbonated water (CBW), salt fluid (SAF), sugar fluid (SUF), and distilled water (DW) were used as fluids, and ultrasound scans were performed at depths of 1.5 cm and 3.0 cm from the surface of the tank, using B-mode and color Doppler effects. All fluids tested showed color Doppler effects, but CBW had the highest doppler shift and the least variation with depth. In conclusion, we determined that CBW was the most suitable fluid to be used as a doppler fluid and confirmed that the bubbles dissolved in CBW act as doppler scatterers, just like red blood cells inside human blood. Therefore, it is possible that CBW can be used as a blood-mimicking fluid in doppler ultrasound phantoms through further research, and this study will provide basic data.

• Journal of Biomedical Engineering Research
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• v.8 no.1
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• pp.75-80
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• 1987

With the conventional CW Doppler velocity meter, bl-directional velocities cannot be separated. The new CW Doppler system uses quadrature detection and phase rotation to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction, is fabricated. Specially, this system shows that phase rotation method for flow direction separation provides easy and satisfactory feature. From in vivo blood flow measurement, we can easily differentiate typical artery flow from vein flow, and measure both velocity characteristics qualitatively.

• The Journal of Korean Medicine
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• v.31 no.4
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• pp.178-186
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• 2010

Objectives: This study was to investigate the effect of moxibustion on peripheral blood flow by Doppler ultrasound in post-stroke hemiplegia patients. Methods: Moxibustion was applied on the points of LI4, TE3, TE5 and LI11 on the affected side, and blood flow of the radial artery was measured using the Minimax-Doppler-K device. Blood flow velocity and pulsation index were analyzed before, during, and after moxibustion. Results: The mean value of blood flow velocity in 13 patients showed a tendency of increase during moxibustion, but there was no significant difference in blood flow velocity before and after moxibustion, or pulsation index during and after moxibustion. In addition, among the five patients who showed marked increase tendency on the blood velocity graph, there was significant increase in blood velocity during, and after moxibustion compared with before moxibustion. Conclusions: This study suggests that moxibustion has an effect on peripheral blood flow in stroke patients with hemiplegia. Further validity tests with a larger scale sample are needed for the evidence of its practical use.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.379-387
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• 2008

Among methods to eliminate aliasing effects, the method of increasing velocity scale gradually eliminated the phenomenon in which the direction of the blood flow appeared in reverse. It was done by increasing the velocity scale while maintaining other parameters in the same state. The method of setting the Doppler angle to $0^{\circ}$ did not show significant changes in the wave pattern of the spectrum according to the angle. In actual ultrasonography tests, more accurate tests are expected to be carried out by applying variations to the velocity scale under the considerations of speed, accuracy, and convenience of the examination. The results showed that blood flow velocity increases exponentially according to the Doppler Angle. When the angle goes over $70^{\circ}$, the velocity value increases to an unmeasurable state. This indicates that in blood flow velocity measurements, the blood flow velocity is very dependent on the Doppler Angle. It also shows that the error increases when the incidence angle to the direction of blood flow exceeds $60^{\circ}$, and when the angle exceeds $70^{\circ}$, the error becomes even greater. In addition, he experiment results showed that an angle below $60^{\circ}$ is appropriate and for blood flow velocity measurements in extremity vessels, the most appropriate Doppler Angle is from $45^{\circ}$ to $60^{\circ}$.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.15-18
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• 1995

Three-dimensional steady and pulsatile flow experiments and numerical simulations have conducted to investigate the flow characteristics in the aortic bifurcation model. In vitro velocity measurements were made using both laser Doppler anemometry and pulsed Doppler ultrasound velocimetry. In this study, flow phenomena in the aortic bifurcation model are discussed extensively and the numerical results are compared with experimental results.

• The korean journal of orthodontics
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• v.39 no.6
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• pp.372-382
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• 2009

Objective: This study was to change of pulp blood flow among maxillary and mandibular anterior tooth with mild crowding and adjacent teeth using Ultrasound Doppler graphy. Methods: The change of pulp blood flow was measured three times using Ultrasound Doppler graphy; before the attachment of brackets, after 3 week, and after 6 week. The sample consists of 15 year old eighteen patients. Results: Before the attachment of brackets, after 3 weeks, and after 6 weeks, there were no significant differences in the change of pulp blood flow in each part (maxilla and mandible) and each tooth according to period. In addition, to compare internal dangerousness of loss of the pulp vitality, when pulp blood flow is compared in each tooth before orthodontic treatment, there were no statistically significant differences in maxillary lateral incisor and mandibular canine but it showed low values in all measurement items (p > 0.05). Conclusions: Results of this study can be not only methodological preliminary data in further study such as tooth movement type of Ultrasound Doppler graphy and particular study considered the patient age, but also reference materials for the loss of pulp vitality in orthodontic treatment.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.705-708
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• 1988

Ultrasound Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. Pulsed Doppler System uses Phase detector and zerocrossing method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time domain, had been fabricated. But time-domain analyzing such as audio evaluation and zerocrossing detection for instantaneous and mean frequency measurement doesn't, provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency domain technique to improve system performance. In this paper, we describe a unit which is composed of Pulsed Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of blood Signal.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.709-712
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• 1988

Ultrasonic Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. CW(Continuous-Wave) Doppler System uses quadrature detection and phase rotation method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time-domain, had been fabricated. But time-domain analyzing such as audio evaluation and zero- crossing detection for instantaneous and mean frequnecy measurement do not provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency-domain technique to improve system performance. In this paper, we describe a unit which is composed of CW Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of Blood signal.