• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.113-116
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• 1995

Steady and physiological flows of a Newtonian fluid and blood in the bifurcated arterial vessel are numerically simulated. Distributions of velocity, pressure and wall shear stress in the bifurcated arterial vessel are calculated to investigate the differences between steady and physiological flows. For the given Reynolds number physiological flow characteristics of a Newtonian fluid and blood in the bifurcated arterial vessel are quite different from those of steady flows. No flow separation or flow reversal in the bifurcated region in the downstream after stenosis appears during the acceleration phase. Also, no recirculation region is seen for steady flows. However, during the deceleration phase the flow began to exhibit flow reversal, which is eventually extended to the entire wall region.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.499-506
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• 1996

Blood flow velocimeter is an essential device to measure the blood flow in skin tissue. In this study, we developed a high-speed LDV(laser Doppler Velocimeter) that has real time processing capability using a DSP(digital signal processing) chip and is able to continuously measure information about blood-flow based on a noninvasive method using self-mixing type laser diode. This LDV system has a simpler structure than any other typical blood flow velocimeter and is composed of new self-mixing probe, stabilizer circuits DSP board, and interf'ace boule We measured velocity of speaker-unit by operational frequencies to identify Doppler effect of this system, performed clinical experiment on bare finger tip and compared it with a commercial euipment BPM403A(USA).

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.3
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• pp.495-509
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• 2021

The study investigated the effects of five commercial body shaping foundation items on clothing pressure, blood flow, body shaping effectiveness, and wearer satisfaction for middle-aged women. The study measured clothing pressure at each of the 10 designated measurement points for twelve subjects wearing the foundations. Blood flow changes were recorded and body shaping effectiveness was analyzed by comparing differences in girth when wearing and not wearing the foundations. The subjects rated wearer comfort along a 7-point Likert scale. The results were that clothing pressure was present at all measurement points, and all foundations placed the least pressure on the anterior underbust girth. In addition, clothing pressure was high in the order of the lateral, posterior, and anterior areas. As clothing pressure increased, blood flow and velocity decreased and overall wearer satisfaction was assessed to be less comfortable. Body shaping effectiveness was evident across all the items, as all decreased girth measurements significantly. In conclusion, the appropriate level of clothing pressure provided by experimental foundations which is positive for blood flow and has an excellent body shaping effect was found to be between 0.53 and 1.77 kPa.

• The Journal of Korea CHUNA Manual Medicine
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• v.1 no.1
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• pp.45-53
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• 2000

Objectives : CHUNA therapy that removes compression of dislocated vertebral bones has positive effect, but sometimes improper CHUNA manual therapy may give rise to negative effect. The aim of this study is to make sure that cervical CHUNA manual therapy give positive effect or negative effect to the blood flow velocity of vertebral artery(VA) and basilar artery(BA) by Trancranial Doppler sonography(TCD). Methods : We performed TCD study on 20patients(male 5, female 15, mean ages 38.5 years) with diagnosis like cervical movement related disorder, headache or dizziness. After we measured mean blood flow velocity(Vm) of VA and BA before cervical CHUNA therapy(Pre-CCT) and after cervical CHUNA therapy(Post-CCT), statistically evaluated the results. Results: The patients received cervical CHUNA therapy for TA sequel, HIVD of cervical spine, headache, dizziness, neck stiffness etc. VA Vm was $31.9{\pm}8.0cm/sec$ before CHUNA therapy, but significantly increased $35.0{\pm}8.7cm/sec$ after CHUNA therapy (p < 0.05). But, there was no significant variation of BA Vm between $41.8{\pm}7.5cm/sec$ Pre-CCT and $41.2{\pm}8.5cm/sec$ Post-CCT(p>0.05). Though VA Vm slightly increased after CHUNA therapy in normal range group, there was no significant variation between VA Vm Pre-CCT and VA Vm Post~CCT. In VA Vm decrease group, VA Vm significantly increased after CHUNA therapy(p<0.05). But, there was no significant variation of BA Vm between Pre-CCT and Post-CCT in BA Vm normal range group and BA Vm decrease group(p>0.05). Conclusions: These findings suggest that cervical CHUNA manual therapy have positive effect on blood flow velocity of VA and BA.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.169-182
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• 1986

Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood-flow-velocity, velocity profile, and volume-blood-flow. This system is more powerful compare with 2-dimensional B-scan tissue image. A system has been deve- loped and ii being evaluated using TMS 32010 DSP. We use this DSP for the purpose of real-time spectrum analyzer to obtain spectrogram in singlegate pulsed Doppler system and for the serial comb filter to cancel clutter and zero crossing counter to estimate Doppler mean frequency in multigate pulsed Doppler system. The Doppler shift of the backscattered signals is sensed in a phase detector. This Doppler signal corresponds to the mean velocity over a some region in space defined by the ultrasonic beam dimensions, transmitted pulse duration, and transducer ban(iwidth. Multi- gate pulsed Doppler system enable the transcutaneous and simultaneous assessment of the velocities in a number of adjacent sample volumes as a continuous function of time. A multigate pulsed Doppler system processing the information originating from presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.516-519
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• 2001

To diagnose a patient's blood vessel disease, apoplexy, hypertension, arteriosclerosis, the blood velocity is very important. Determining the blood velocity methods using ultrasound are Continuous Doppler System and Pulse Doppler System. In using the Pulse Doppler System, we can obtain the position of blood velocity. But it is more complex hardware than Continuous Doppler System and it has low SNR(signal-noise ratio). So in this study, to obtain a believable information we use the Continuous Pulse Doppler System. Thus system have analog part and digital part. In analog part is composed of ultrasound generating part, the amplifying part to amplify the received signal from ultrasound sensor, the demodulation part to detect blood velocity and the filtering part to remove the noise. In digital part is composed of the A/D conversion part, digital signal processing part, and the communication part to communicate the PC. In this study to implement efficient ultrasound blood velocity measurement system, we can get the patient's blood velocity information in realtime. Thus, It is a useful in the accurate diagnosis with C.T(computered tomography), M.R.I(magnetic resonance imaging).

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.10-12
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• 2008

Hemodynamic features of blood flow in the abdominal aorta aneurysm (AAA) are very important, because they are closely related with the rupture of aneurysm to death. It has been considered that the wall shear stress of blood flows influences the formation, growth, and rupture of AAA. On this account, it is important to understand the flow structure of blood in the aneurysm. In this study, the whole velocity field information inside a typical AAA was measured using an in vitro AAA model under the pulsatile flow condition. The vessel geometry was reconstructed based on the computerized tomography (CT) data of a patient. The AAA model was made by using a rapid prototyping (RP) method, based on the reconstructed vessel geometry. Velocity fields in the AAA model were measured at different pulsatile phases using a PIV (particle image velocimetry) system. As experimental results, a large-scale vortex is formed inside the AAA model and the vortices located near the AAA wall are supposed to increase the local pressure and wall shear stress. In this study, the AAA wall stress found to be was one of the most important governing parameters giving rise to the ruptured aneurysm.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.77-79
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• 2007

The purpose of this study was to suggest a new detection method for early diagnosing diabetic neuropathic foot by obtaining a ratio of toe to figer blood flow using photoplethysmography(PPG). Nerve conduction velocity (NCV) has been routinely used for diagnosing neuropathic foot, but it applies strong electric stimulus to peripheries resulting in stress and pain. The blood flow ratio of diabetic neuropathy(0.96${\pm}$0.20) was significantly higher in comoarison to normal control group(0.46${\pm}$0.15, left : p<0.05, right : p<0.05) and non-neuropathy diabetic group(0.49${\pm}$0.21, left: p<0.05. right: p<0.05).

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.343-350
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• 2011

The compliance and stiffness of artery are closely related with disease of arteries. Pulse wave velocity(PWV) in the blood vessel is a basic and common parameter in the hemodynamics of blood pressure and blood flow wave traveling in arteries because the PWV is affected directly by the conditions of blood vessels. However, there is no standardized method to measure the PWV and it is difficult to measure. The conventional PWV measurement has being done by manual calculation of the pulse wave transmission time between coronary arterial proximal and distal points on a strip chart on which the pulse wave and ECG signal are recorded. In this study, a pressure sensor consisting of strain gauges is used to measure the blood pressure of arteries in invasive method and regular ECG electrodes are used to record the ECG signal. The R-peak point of ECG is extracted by using a reference level and time windowing technique and the ascending starting point of blood pressure is determined by using differentiation of the blood pressure signal and time windowing technique. The algorithm proposed in this study, which can measure PWV automatically, shows robust and good results in the extraction of feature points and calculation of PWV.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.959-963
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• 2006

A three-dimensional elastic blood vessel model with internal diameter variation is considered to investigate internal flow characteristics and effects of structural deformation. Also, computational analyses for both the rigid model and the fully-coupled FSI model have been conducted in order to compare the shear stress, pressure distribution, and flow velocity in detail. A 70% narrowing area of asymmetric blood vessel model was especially investigated to show the versatility of fluid-structure interaction phenomenon. The results reveal that effect of fluid-structure interaction is very important to accurately investigate the flow characteristics of the blood vessel.