• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.11 no.1
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• pp.31-39
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• 2007

A pedagogic model for blood flow is introduced to help medicine majors understand a simplified version of Navier-Stokes equations which is known to be a good tool for interpreting the phenomena in blood flow. The pressure gradient consists of a time-independent part known as Hagen-Poiseuille's gradient and a time-dependent part known as Sexl's, and the model formula for the volume rate of blood flow is reduced to a very simple form. For demonstration, the blood rate in human aorta system is analyzed in connection with the time-dependence of pressure gradient. It is shown for Sexl's part that the flow rate lags the pressure gradient by ${\pi}/2$, which is thought to be due to the relaxation process involved.

• Korea-Australia Rheology Journal
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• v.19 no.2
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• pp.89-95
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• 2007

The flow characteristics of chicken blood in a micro-tube with a $100{\mu}m$ diameter are investigated using a micro-Particle Image Velocimetry (PIV) technique. Chicken blood with 40% hematocrit is supplied into the micro-tube using a syringe pump. For comparison, the same experiments are repeated for human blood with 40% hematocrit. Chicken blood flow has a cell-free layer near the tube wall, and this layer's thickness increases with the increased flow speed due to radial migration. As a hemorheological feature, the aggregation index of chicken blood is about 50% less than that of human blood. Therefore, the non-Newtonian fluid features of chicken blood are not very remarkable compared with those of human blood. As the flow rate increases, the blunt velocity profile in the central region of the micro-tube sharpens, and the parabolicshaped shear stress distribution becomes to have a linear profile. The viscosity of both blood samples in a low shear rate condition is overestimated, while the viscosity in a high shear rate range is underestimated due to radial migration and the presence of a cell-depleted layer.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.224-227
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• 2010

In the present study, the characteristics of blood flow inside a carotid artery numerically investigated with shear rate specific blood viscosity. To simulate the blood flow with a patient-specific arterial geometry, the geometry of a carotid artery was constructed from 2D rain MRA data. The measured data of blood flow velocity at the common carotid artery were used as boundary conditions of the simulation. For the blood rheology data to be used in the simulation, the patient specific blood viscosity over the whole ranges of shear rate was obtained using $BioVisco^{TM}$. From the numerical results of the blood flow in the carotid artery, the increase of blood viscosity and the decrease of wall shear stress could be found in the carotid bifurcated region, more specifically at the post-plaque dilated region. These characteristics of blood viscosity and wall shear stress can be used more precisely and efficiently to predict the region vulnerable to plaque growht or thrombosis on top of the plaque.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.288-290
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• 2003

Artificial heart is divided by pulsation flow type and continuous flow type according to blood circulation pattern. Axial flow blood pump is a kind of continuous flow type artificial heart. Axial flow blood pump would be different pump performance according to impeller's shape and rotating velocity. Pump performance be able to compare by flow rate according to differential pressure and Impeller's rotating velocity. It confirms Impeller model of better efficiency according to compare Pump performance of axial flow blood pump using CFD with actual experiment result.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.152-155
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• 2008

The blood flow characteristics have been closely related to various cardiovascular diseases, it is very important to predict them accurate enough in an efficient way. Thus, this paper proposes a one-dimensional spectral element model for the blood flow through blood vessels. The spectral element model is formulated by using the variational method. The nonlinear terms in spectral element model are all treated as the pseudo-force and an iterative solution method is applied in the frequency domain.

• Journal of Ginseng Research
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• v.34 no.3
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• pp.237-245
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• 2010

The purpose of this study was to evaluate the effect of Korean red ginseng (KRG) on ocular blood flow in patients with glaucoma. In a prospective, randomized, placebo-controlled, double-masked crossover trial, 36 patients with open-angle glaucoma were consecutively recruited. Subjects were randomly assigned into two groups. Group A received 1.5 g KRG, administered orally three times daily for 12 weeks, followed by a wash-out period of 8 weeks and 12 weeks of placebo treatment (identical capsules filled with 1.5 g corn starch). Group B underwent the same regimen, but took the placebo first and then KRG. Blood pressure, heart rate, and intraocular pressure were measured at baseline and at the end of each phase of the study. Visual field examination and ocular blood flow measurements by the Heidelberg Retina Flowmeter were performed at baseline and at the end of each phase of the study. Changes in blood pressure, heart rate, intraocular pressure, visual field indices, and retinal peripapillary blood flow were evaluated. Blood pressure, heart rate, intraocular pressure, and visual field indices did not change after placebo or KRG treatment. After KRG treatment, retinal peripapillary blood flow in the temporal peripapillary region significantly improved (p=0.005). No significant changes were found in retinal peripapillary blood flow in either the rim region or the nasal peripapillary region (p=0.051 and 0.278, respectively). KRG ingestion appears to improve retinal peripapillary blood flow in patients with open-angle glaucoma. These results imply that KRG ingestion might be helpful for glaucoma management.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.345-353
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• 2013

Objective: This research measured physiological and psychological effects of Vibroacoustic stimulation(VA) to scapular and sacrum of supine position on the mattress. Background: When vibroacoustic stimulation applies to human body, it has a positive influence on physiological and psychological effects by stimulating the organs, tissues and cells of whole body. Method: This experiment was conducted to 10 normal males in two conditions: no stimulation and vibroacoustic stimulation. No stimulation experiment was executed as a supine position for 30 minutes without any vibrational stimulus, while vibroacoustic stimulation was transmitted by the vibrational speaker, which uses 40Hz frequency. Subjects had a laser Doppler flowmeter probe in scapular, sacrum, and also had 8 channel electroencephalogram(EEG) measurement sensor in the scalp. Blood pressure and skin temperature were measured in two conditions with an underlying posture for 30 minutes. Additionally, blood flow rate and EEG were measured before and after for two minutes on two conditions. Results: According to the vibroacoustic stimulation, blood flow rate and skin temperature were increased, while blood pressure was decreased. When using vibroacoustic stimulation compared to no stimulation, blood flow rate went approximately two times higher, and skin temperature also higher 3~4 times. Furthermore, the relative alpha power of brain wave was significantly increased when we applied to vibroacoustic stimulation. Conclusion: This experiment tested the VAT embedded in mattress in two conditions. According to this experiment, VAT decreases blood pressure, improves not only a physiological effect on blood flow rate as well as skin temperature, but also psychological functions by increasing relative alpha power. Application: The results of the publishing trend analysis might help physiological and psychological effects of vibroacoustic stimulation.

• Korea-Australia Rheology Journal
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• v.21 no.2
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• pp.119-126
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• 2009

A numerical analysis is performed to investigate the effect of rotation on the blood flow characteristics with four different angular velocities. The artery has a cylindrical shape with 50% stenosis rate symmetrically distributed at the middle. Blood flow is considered a non-Newtonian fluid. Using the Carreau model, we apply the pulsatile velocity profile at the inlet boundary. The period of the heart beat is one second. In comparison with no-rotation case, the flow recirculation zone (FRZ) contracts and its duration is reduced in axially rotating artery. Also wall shear stress is larger after the FRZ disappears. Although the geometry of artery is axisymmetry, the spiral wave and asymmetric flow occur clearly at the small rotation rate. It is caused that the flow is influenced by the effects of the rotation and the stenosis at same time.

• Journal of Chest Surgery
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• v.24 no.12
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• pp.1167-1172
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• 1991

Since March 1988 we have performed 133 arteriovenous fistulae for hemodialysis in 121 patients with chronic renal failure. Of the 133 cases of arteriovenous fistulae, follow-up evaluation was possible for 80 cases which performed in 69 patients. The relation between blood flow and patency rate and duration of arteriovenous fistula was examined. The overall 6 - 12 - 18 -, and 24 - month patency rates of arteriovenous fistulae were 82%, 64%a, 62%, and 57%, respectively. The maximum blood flow was 150 ~ 350ml /min[mean 217.1$\pm$44.27]. The patency duration was evaluated in patients divided into three groups owing to maximum blood flow through the fistulae. The range of maximum blood flow was 150 ~ 200ml /min for group A, 200 ~ 250ml /min for group B, and above 250ml /min for group C. The mean duration of the patency was 10.7$\pm$7.60 months in group A, 14.9$\pm$9.82 months in group B, and 21.6$\pm$11.16 months in group C[p<0 05]. With increased maximum blood flow, the duration of the patency was longer in group A than group B and C [r=0.39, p<0. 05]. The maintenance blood flow was 100 ~ 250ml /min[mean 179.2$\pm$37.26 ml/min]. When the maintenance blood flow was above 200ml /min, long-term patency rate was higher than the group below 200ml /min[r=0.48, p<0.01]. In the same range of blood flow, patency duration of the patients with using their own blood vessels were longer than the patients with using vascular graft for A-V fistula. We concluded that the patency of the arteriovenous fistulae was closely correlated with the blood flow through the fistulae.

• 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.