• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1182-1188
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• 2005

An x-ray PIV (Particle Image Velocimetry) technique was developed to measure quantitative information on flows inside opaque conduits and on opaque-fluid flows. At first, the developed x-ray PIV technique was applied to flow in an opaque Teflon tube. To acquire x-ray images suitable for PIV velocity field measurements, refraction-based edge enhancement mechanism was employed using detectable tracer particles. The optimal distance between with the sample and detector was experimentally determined. The resulting amassed velocity field data were in reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to blood flow in a microchannel. The flow pattern of blood was visualifed by enhancing the diffraction/interference -bas ed characteristic s of blood cells on synchrotron x-rays without any contrast agent or tracer particles. That is, the flow-pattern image of blood was achieved by optimizing the sample (blood) to detector distance and the sample thickness. Quantitative velocity field information was obtained by applying PIV algorithm to the enhanced x-ray flow images. The measured velocity field data show a typical flow structure of flow in a macro-scale channel.

• 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.

• Journal of Magnetics
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• v.20 no.1
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• pp.47-51
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• 2015

We measured radial arterial pulse signals using a prototype of a clip-type pulsimeter equipped with a permanent magnet and a Hall device, which produced signals through a voltage-detecting circuit. The systolic peak time and the reflective peak time for a temporally pulsed signal were analyzed for an arbitrary pulse wave at one position of a small permanent magnet. The measured value of the peripheral pulse wave velocity was about 1.25-1.52 m/s, demonstrating the accuracy of this new method. To measure the peripheral blood flow velocity, we simultaneously connected the radial artery pulsimeter to a photoplethysmography meter. The average value of the peripheral blood flow velocity was about 0.27-0.50 m/s.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.11a
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• pp.62-68
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• 2000

The aim of the study was to compare effects of music and white noise on the recovery of facial blood flow parameters after stressful visual stimulation. Twenty-nine subjects participated in the experiment. Three visual stimulation sessions with aversive slides (the IAPS, disgust category) were followed by subjectively "pleasant" (in the first session), "sad" music (in the second ), and white noise (in the third ). Order of sessions was counterbalanced. Blood flow parameters (peak blood flow, blood flow velocity, blood volume) were recorded by Laser Doppler single-crystal system (LASERFLO BPM 403A) interfaced through BIOPAC 100WS with AcqKnowledge software (v.3.5) and analyzed in off-line mode. Aversive visual stimulation itself decreased blood flow and velocity in all 3 sessions. Both "pleasant" and "sad" music led to the restoration of baseline levels in all blood flow parameters, while noise did not enhance recovery process. Music on post-stress recovery had significant change in peak blood flow and blood flow velocity, but not in blood volume measures. Pleasant music had bigger effects on post-stress recovery in peak blood flow and flow velocity than white noise. It reveals that music exerted positive modulatory effects on facial vascular activity measures during recovery from negative emotional state elicited by stressful slides. Results partially support the undoing hypothesis of Levenson (1994), which states that positive emotions may facilitate process of recovery from negative emotions.

• Journal of Biomedical Engineering Research
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• v.31 no.2
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• pp.99-105
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• 2010

In order to obtain velocity profile of blood flow with high spatial resolution, a micro PIV technique consisted of a fluorescent microscope, double-pulsed YAG laser, cooled CCD camera was applied to in-vitro blood flow experiment through a micro round tube of a diameter $100{\mu}m$. Velocity distributions of blood flow for rabbit were obtained. The viscosity profiles for shear rate were found at flowing condition. To provide hemorheological characteristics of blood flow, the viscosities for shear rate were evaluated. The viscosity of blood also steeply increase by decreasing shear rate resulting in Non-Newtonian flow, especially in low shear rate region caused by RBC rheological properties. The results show typical characteristics of Non-Newtonian characteristics from the results of velocity profile and viscosity for blood flow. From the inflection points, cell free layer and two-phase flow consisted with plasma and suspensions including RBCs can be separated.

• The Journal of Korean Physical Therapy
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• v.11 no.2
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• pp.37-42
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• 1999

The purpose of this study was to determine whether percutaneous interferential current stimulation on thoracic sympathetic ganglia with amplitude modulated frequency (AMF) $90\~100$ bps and subthreshold of muscle contraction for 10 minutes on peripheral blood flow velocity in healthy subjects. Thirty-seven healthy volunteers were assigned randomly into an experimental group (n=25) and a control group (n=12). the experimental group received interferential current stimulation with subthreshold of the muscle contraction of current at AMF $90\~100$ bps on $1st\~5th$ thoracic sympathetic ganglial region for 10 minutes. The control group received same handling and electode placement, but no current was applied. Using a Doppler blood flow meter, the radial arterial blood flow velocities and the pulse raters were determined for two-way analysis of variance for repeated measures on time and group. There were no significant difference between the two groups with respect to the changes in arterial blood flow velocity and pulse rate over the four measurement times. Interferential current stimulation did not change in mean blood flow velocity and pulse rate. We conclude that interferential current stimulation on the thoracic sympathetic ganglia, as used in this study, did not dilate peripheral artery. This results suggests that interferential current stimulation dose not alter the activtiy of sympathetic nerve.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.179-186
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• 1997

Steady and physiological flows of a Newtonian fluid and blood in the abdominal gorta/iliac artery bifurcation are numerically simulated to understand the etiology and pathogenesis of atherosclerosis. Distributions of velocity, pressure, and wall shear stress in the bifurcated arterial vessel model are calculated to investigate the differences of flow characteristics between steady and physiological flows and to compare flow characteristics of blood with that of a Newtonian fluid For the given Reynolds number the flow characteristics of physiological flows for a Newtonian fluid and blood in the bifurcated arterial vessel are quite different from thcse of steady flows. No flow separation or flow reversal in the bifurcated region appears downstream of a stenosis during the acceleration phase. However, during the deceleration phase the flow exhibits flow separation in the outer walls of daugtlter branches, which extends to the entire wall region.

• The Journal of Korean Physical Therapy
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• v.22 no.5
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• pp.49-56
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• 2010

Purpose: The aim of this study was to evaluate a possible role for cranial artery velocity in cervicogenic headache. Methods: We studied 13 patients with cervicogenic headaches (M=9, F=4, age=$24.50{\pm}3.50\;y$) these were compared to 20 normal subjects (M=10, F=10, age=$23.30{\pm}2.90\;y$). Cervicogenic headache patients were divided into two groups (a myofascial relaxation group, a placebo group). Pain levels were measured using a visual analog scale (VAS). Transcranial Doppler (TCD) ultrasound recordings were used to measure blood flow velocity in the cranial artery. Results: Cervicogenic headache patients exhibited a significantly lower blood flow velocity in the middle cerebral artery. The patients who received an intervention had a significantly higher blood flow velocity in the left middle cerebral artery, right vertebral artery and basilar artery. Compared to the placebo group, the myofascial relaxation group exhibited a significantly decreased level of pain. Conclusion: Cervicogenic headache is pain referred to the head from a source in the cervical spine. Manual therapy affect to cervical spine and soft tissue as well as the passage of these vessels and nerves to recover because it is thought to be able to help.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.1 no.2
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• pp.1-9
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• 2003

The purpose of this study was to analyze the effect given to the variable details which disturb the flow of blood in brain artery disease through Aerobic exercises. It chose the subjects of study : 5 persons in an exercise group and 5 persons in a non-exercise group. Peak brain blood velocity, mean velocity, and resistance & artery stricture ratio were measured with TCD, measure machine for brain artery blood flow. The conclusion of the study was as follows: 1. At pre-test of an exercises group and a non-exercise group, PBV, MBV, BRI, ASI of a non-exercise group were showed much lower in the variation of left common carotid artery(LCCA). 2. At post-test of an aerobic exercises group and a non-exercise group, PBV, MBV, BRI, ASI of a non-exercise group were showed just a little decrease ratio but were not significant different in the variation of left common carotid artery(LCCA). Viewing on the base of these result, continuing exercises promote the functional improvement of the heart blood system and were showed the positive variation of artery stricture ratio according to brain blood flow velocity, the pulse and resistance or blood velocity. Therefore programs for prescriptions through aerobic exercises must be developed in many ways.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.111-112
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• 2006

In order to investigate flow characteristics of blood flow in a micro tube ($100{\mu}m$ in diameter) according to hematocrit, in-vitro experiments were carried out using a micro-PIV technique. The micro-PIV system consists of a microscope, a 2 head Nd:YAG laser, a 12 bit cooled CCD camera and a delay generator. Blood was supplied into the micro tube using a syringe pump. Hematocrit of blood was controlled to be 20%, 30% and 40%. The blood flow has a cell free layer near the tube wall and its thickness was changed with increasing the flow rate and hematocrit. The hemorheological characteristics such as shear rate and viscosity were evaluated using the velocity field data measured. As the flow rate increased, the blunt velocity profile in the tube center was sharpened. The viscosity of blood was rapidly increased with decreasing shear rate, especially in the region of low shear rate, changing RBC rheological properties. The variation of velocity profile and blood viscosity shows typical characteristics of Non-Newtonian fluids. On the basis of inflection points, the cell free layer and two-phase flow consisting of plasma and suspensions including RBCs were clearly discriminated.