• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.96-101
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• 2000

In this paper, an experimental investigation of characteristics of developing transitional steady flows in a square-sectional 180 urved duct is presented. The experimental study is carried out to measure axial velocity profiles by using Laser Doppler Velocimeter (LDV) system. The flow development is found to depend upon Dean number and curvature ratio. For transitional steady flows, the maximum velocity position of axial velocity profiles begins to incline toward the outer wall from $\phi$=$30^{\circ}$bended angle, velocity profiles in center of the duct have lower value than those of the inner and outer walls because of the centrifugal forces.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1184-1195
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• 2001

Analysis of fluid flow in rectangular ducts has been conducted since it has a wide application. The purpose is to provide experimental data for the comparison with computational results. Velocity distributions inside a rectangular duct with $90^{\circ}$ mitered elbow are measured by 5W laser doppler velocity meter for Reynolds numbers of 4,049, 8,104, and 12,186. Flow rates obtained by the integration of measured velocity profile at three cross-sections, which are inlet, middle section after the elbow, and outlet, have errors less than 0.9% among them. Turbulent fluctuation components in two directions are found to have almost similar magnitude each other at a certain location due to the isotropic characteristic of turbulence.

• Clinics in Shoulder and Elbow
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• v.27 no.1
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• pp.11-17
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• 2024

Background: Rotator cuff tears are often associated with synovitis, but the ability of noninvasive ultrasonography to predict the severity of synovitis remains unclear. We investigated whether ultrasound parameters, namely peak systolic velocity in the anterior humeral circumflex artery and Doppler activity in the glenohumeral joint and subacromial space, reflect synovitis severity. Methods: A total of 54 patients undergoing arthroscopic rotator cuff repair were selected. Doppler ultrasound was used to measure peak systolic velocity in the anterior humeral circumflex artery and Doppler activity in the glenohumeral joint and subacromial space, and these values were compared with the intraoperative synovitis score in univariate and multivariate analyses. Results: Univariate analyses revealed that tear size, peak systolic velocity in the anterior humeral circumflex artery, and Doppler activity in the glenohumeral joint were associated with synovitis in the glenohumeral joint (P=0.02, P<0.001, P=0.02, respectively). In the subacromial space, tear size, peak systolic velocity in the anterior humeral circumflex artery, and Doppler activity in the subacromial space were associated with synovitis severity (P=0.02, P<0.001, P=0.02, respectively). Multivariate analyses indicated that tear size and peak systolic velocity in the anterior humeral circumflex artery were independently associated with synovitis scores in both the glenohumeral joint and the subacromial space (all P<0.05). Conclusions: These findings demonstrate that tear size and peak systolic velocity in the anterior humeral circumflex artery, which can both be measured noninvasively, are useful indicators of synovitis severity.

• Journal of Biomedical Engineering Research
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• v.16 no.3
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• pp.279-288
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• 1995

Ultrasonic Doppler systems for the purpose of estimating blood flow velocity, blood flow volume, and flow imaging are commonly used due to advantages of non-invasive and real time observation. Specially, the technical developments of color flow mapping (2-D Doppler) systems have made a relatively rapid progress. However, the 2-D Doppler systems have several problems, such as the range ambiguity, low signal to noise ratio, and slow frame rate. The slow frame rate problem is resolved by using the spatial average which is a method to acquire more data samples for mean frequency estimation. In this paper, spatial average method using the 2nd order sampling instead of quadrature sampling is proposed. The experimental results show that the proposed methods have good performance and easy application to the color flow mapping system.

• The Journal of the Society of Stroke on Korean Medicine
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• v.6 no.1
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• pp.45-53
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• 2005

Objective : This study was performed to examine the relationship between cerebral blood vessel with meridian by using Transcranial Doppler Ultrasonography(TCD) Method : Monitoring of TCD was examined in 10 healthy people in their twenties (mean age was 26.5±1.00). Each examination was performed before & after acupuncture. Three Meridian were tested. Those were Stomach Meridian, Bladder Meridian & Gallbladder Meridian. Maximum velocity and Mean velocity were analyzed from TCD on different vessel. Result : The results showed significant(p<0.05; Wilcoxon signed rank test) change in some cerebral blood flow after acupuncture. Conclusion : There was the relationship between Meridian and cerebral blood vessel.

• Journal of Biomedical Engineering Research
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• v.7 no.1
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• pp.75-79
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• 1986

In this paper, a multigate pulsed doppler system with parallel signal processing which enables the transcutaneous assesment of the blood-flow velocities of five adjacent sample volumes is developed. The outputs of the system are audio signals, velocity curves and velocity profiles of 5 adjacent sample volumes. We have applied to the major superficial arteries and obtained the detailed information about the time dependent blood-flow behavior.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.317-324
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• 2008

This paper presents an optical doppler tomography(ODT) system using a speaker as a method to achieve depth measurement in a flowing sample. The use of the speaker provides easy implementation with a low cost. The nonlinear characteristics of the speaker has hindered its adaptation because it produces inconsistent fringe frequencies at different depths. This paper reports an adaptive algorithm to compensate the nonlinear characteristics, and could, resultantly, acquire the Doppler frequency shift caused by the sample. The experiment utilizes a flowing scattering particle solution in a capillary tube at a certain flow rate. The Doppler frequency profile over the lumen was calculated by using spectrogram method. and we obtained the velocity image of the sample.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.39-42
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• 1992

Color Doppler flow mapping (CDFM) was performed on an $\underline{in\;vitro}$ experimental setup with a regurgitant moving orifice using the proximal isovelocity surface area (PISA) technique. PISA flow rates underestimated actual flow rates by as much as 65%, which is very important in diagnosing patients with valvular regurgitations or stenosis. The correction factor considering the velocity of the orifice improved the PISA flow rates.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.720-726
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• 2001

Two-dimensional, angle-resolved LDV(Laser Doppler Velocimetry) measurements of the turbulent rotating flow field in a confined cylinder have been performed. The configurations of interest are flows between a rotating upper disk with a rod attached by a disk or impeller(${\theta}= 90^{\circ},\;45^{\circ}$) and a stationary lower disk in a confined cylinder. The mean flow velocity as well as the turbulent intensity of the flow field have been measured. The results show that the flow is strongly dependent on the position of the impellers or the disk, negligibly affected by the Reynolds number in turbulent flow. It is observed that the mixing effect of the axial flow impeller(${\theta}= 45^{\circ}$) is better than that of the radial flow impeller(${\theta}= 90^{\circ}$) or a disk.

• The Journal of Korean Medicine
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• v.17 no.1 s.31
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• pp.345-360
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• 1996

Background and Purpose: To evaluate the blood flow velocity using doppler ultrasound of the carotid artery, vertebral artery, and basilar artery in stroke patients Material and Methods: To evaluate the blood flow, I measured the peak systolic velocity and mean velocity of the common carotid artery(CCA), internal carotid artery(ICA), external carotid artery (ECA). vertebral artery(VA), and basilar artery(BA) in 44 stroke patients and 15 healthy adults. To investigate the difference between ischemic stroke patients and normal healthy adults, I selected 44 ischemic stroke patients diagnosed by brain CT and brain MRI, and 15 healthy adults who did not have any symptoms of stroke, hypertension, heart disease, and diabetes melitus. Results: Peak velocity in normal adults was 50.6${\pm}$1.6cm/sec in the CCA, 67.2${\pm}$1.7cm/sec in the ICA, 62.5${\pm}$2.4cm/see in the ECA, 45.5${\pm}$1.9cm/sec VA. and 50.5${\pm}$3.5cm/sec in the BA. Mean velocity in normal adults was 26.9${\pm}$1.1cm/sec in the CCA, 43.7${\pm}$1.4cm/sec in the ICA, 26.7${\pm}$1.3cm/sec in the ECA. 31.6${\pm}$1.9cm/sec in the VA and 33.0${\pm}$2.6cm/sec in the BA. In this study, there was a significant increase in the velocity of ICA, ECA, and VA of ischemic stroke patients in comparison with normal healthy adults. And the blood flow velocity of this study in the CCA and ECA was different from other reported foreign values and the other known values in my country. Conclusion: There was a significant difference in the blood flow velocity between ischemic stroke patients and normal healthy adults. And the blood flow velocity of this study was different from other reported foreign values and the other known values in my country. Therefore, it needs more detailed studies about old aged Korean and ischemic stroke patients than previous studies.