• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.11 s.242
• /
• pp.1182-1188
• /
• 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 computational fluids engineering
• /
• v.18 no.3
• /
• pp.14-19
• /
• 2013

Renal failure patients have to operate arteriovenous graft for hemodialysis. Blood flow characteristics influence the patency rate of arteriovenous graft. Numerical investigation is performed with the arteriovenous graft according to injection of blood. As a result, when the injection is not applied to venous graft, the low wall shear stress region appears at venous anastomosis. It may cause intimal hyperplasia at venous anastomosis.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.373-374
• /
• 2002

Magnetic fluid seals are used in a wide variety of gas and dust sealing applications. However, it is difficult to seal for liquid because of its characteristic. This study will be a basic guide for a magnetic fluid seal for liquid, especially for blood to be practically used in medical instruments such as rotary blood pumps by clarifying its seal properties. Sealing pressure test, durability test, and hemolysis test have been conducted for this seal. In this study, magnetic fluid, sealing fluid, eccentricity ratio, revolution speed were selected as parameters. As results of the tests, it has been found that the properties of magnetic fluid seal depend on the solvent and the saturation magnetization of magnetic fluid. Therefore, the selection of magnetic fluid is important for this seal. It also has been found that eccentricity ratio of the shaft caused harmful effect for seal properties. In conclusion, it has been showed that magnetic fluid seals could be possibly used in medical instruments such as blood pumps when blood come in contact with magnetic fluids.

• Korean Journal of Veterinary Research
• /
• v.37 no.4
• /
• pp.883-897
• /
• 1997

Present study was undertaken in order to find out the most significant laboratory test for the early diagnosis of ethylene glycol poisoning in dogs. Seven dogs weighing from 5.0kg to 19.3kg were administered orally 6ml or l0ml of ethylene glycol per kilogram of body weight. In addition to clinical observations, blood samples were taken from the jugular vein on 0, 1, 3, 6, 12, 24 and 48 hours or until death after the adminisration and examined for the hematological, blood chemical, venous blood gas and electrolyte changes. Urine samples were simultaneously taken and examined for pH, protein, glucose and calcium oxalate crystals in the sediments. The results were as follows : 1. All dogs showed marked hypothermia in addition to the characteristic signs of ethylene glycol poisoning until death. 2. No significant hematological changes were observable after the administration of ethylene glycol except the secondary dehydration and stress leukogram. 3. Chemical values related to the liver function(serum glutamic pyruvic transaminase, total serum protein, serum albumin, serum total bilirubin) showed no significant changes during the experimental period in all dogs. 4. Chemical values related to the renal function(BUN and creatinine) showed significant(p<0.0l, p<0.001) increase from 24 hours to death in all dogs. 5. All dogs showed significant(p<0.01, p<0.001) decrease in blood pH from 3 hours to death after the ethylene glycol administration. 6. All dogs showed significant(p<0.05, p<0.01, p<0.001) increaes in anion gap from 1 hour to death after the ethylene glycol administration. 7. All dogs showed significant(p<0.05, p<0.01) decrease in urine pH from 1 hour to 6 hours after the administration of ethylene glycol. 8. Characteristic envelope form of calcium oxalate crystals were found in the urinary sediment from 6 hours after the administration of ethylene glycol in all dogs. 9. Histologically calcium oxalate crystals were found in the renal rubles in all dogs. 10. From these results, it may be concluded that the examinations of urinary sediments for the calcium oxalate crystals, blood or urinary pH and blood anion gap are most reliable tests for the early diagnosis of ethylene glycol poisoning in dogs.

• The Journal of the Korea Contents Association
• /
• v.5 no.5
• /
• pp.296-304
• /
• 2005

Quantitative analysis compare to dynamic characteristic change of the regional cerebral blood volume(rCBV) after development of cerebral fat embolism in cats using perfusion magnetic resonance(MR) Imaging. Twenty cats were used. Linoleic acid (n=11) were injected into the internal carotid artery using microcatheter through the transfemoral approach. Polyvinyl alcohol (Ivalon) (n=9) was injected as a control group. Perfusion MR images were obtained at 30 minutes and 2 hours after embolization, based on T2 and diffusion-weighted images. The data was time-to-signal intensity curve and ${\Delta}R_2^*$ curve were obtained continuously with the aid of home-maid image process algorithm and IDL(interactive data Banguage, USA) softwares. The ratios of rCBV increased significantly at 2 hours compared with those of 30 minutes (P<0.005). In conclusion, cerebral blood flow decreased in cerebral fat embolism immediately after embolization and recovered remarkably in time course. It is thought that clinically informations to dynamic characteristic change of the cerebral hemodynamics to the early finding in cerebral infarction by diffusion weighted imaging(DWI) and perfusion weighted imaging(PWI).

• Journal of Biomedical Engineering Research
• /
• v.13 no.3
• /
• pp.189-194
• /
• 1992

As people's income and intake of animal fat rapidly increase, so does choresterol concentration in blood. Thus diseases such as non-insulin-dependent diabetes mellitus(NIDDM)myocardial infraction, high blood pressure, cerebral stroke resulting from atherosclerosis rapidly increase recently. It is very difficult to diagnose atherosclerosis early since its progress is so slow and there is no sypmtoms in the beginning of the disease. In this study a mechanical characteristic, compliance, of the lower leg arteries was measured noninvasively. Changes of blood volume and pressure were measured using impedance plethysmgraphy and mercury sphygmomanometer, respectively. The compliance was calculated by dividing the change of blood volume by the change of pulse pressure ( systolic-diastolic pressure ) . Subjects were 24 asymptomatic persons ranging (rom 30 Ic 58yeras and 14 diabetics from 41 to 59years. The compliances, mean, and systolic pressures were statistically analyzed using a t-test be- tween the healthy and diabetic groups. The average compliance of the healthy and diabetic group was measured 2.79 and 1.82U1/mmHg/cm, respectively and these were significantly different(p<0.01). It was also found that the compliance is a better parameter in differentiating the vascular disease than mean or systolic blood pressure.

• Proceedings of the KOSOMBE Conference
• /
• v.1996 no.11
• /
• pp.363-367
• /
• 1996

In general, the physiological systems have shown nonlinear complex phenomena. This study analyzes nonlinear characteristics of the flow of peripheral blood vessel dynamics in physiological systems using chaos theory. We performed this study by means of several quantity methods and power spectrum. The quantity methods are a phase space reconstruction and a poincare's map. And the power spectrum method is a conventional linear analysis. Experimental data have been acquired from examining 10 diabetic patients, and 10 control subjects in initial stable state. In acquisition experminetal data, we anlysized the differences of nonlinear characteristics between diabetic group and control group. The results of quality analysis methods showed the flow of peripheral blood vessel had the nonlinear and chaotic characteristics, screening a strange attractor on reconstructed phase space. In conclusion, the flow dynamics of peripheral blood vessel had a chaotic behavior of nonlinear dynamic systems, dynamic system, and differences of characteristic of nonlinear dynamic system.

• The Journal of Korean Medicine
• /
• v.35 no.3
• /
• pp.155-165
• /
• 2014

Objectives: The pulse diagnosis to identify the symptoms has been considered important in Korean medicine. The position and character of disease would be confirmed by pulse diagnosis of left and right radial artery. This paper is to analyze the characteristics and differences of left and right blood vessels. Methods: In this study, left and right radial artery and dorsalis pedis artery was measured and analyzed by using condenser typed pulse analyzer. Commercially available pulse analyzer was used to measure the radial artery. The pulse wave was measured in 20 laboratory healthy men and women. The blood vessel aging degree and index of augmentation of blood vessel was obtained from the measured pulse wave graph and the characteristics and differences of the left and right blood vessel was analyzed. Results: The significant difference of pulse transit time between the right handed and non-right handed was not found. The correlation of radial artery and dorsalis pedis artery had no significant difference. By obtaining the blood vessel aging index (AGI) and augmentation index (AI) of blood vessel at the left and right radial artery, the significant difference between right handed and non-right handed was not found. Conclusions: The result of this study would help to explain the characteristic of blood vessel with respect to the left and right handed. We suggest that research of pulse wave of the left and right blood vessel using pulse analyzer should be needed in further study.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03a
• /
• pp.181-185
• /
• 2008

In this study, we attempted to quantify the relative importance of assumptions regarding blood rheology. Three patient-specific carotid bifurcation geometries and time-varying flow rates were obtained using magnetic resonance imaging. For each subject, CFD simulations were carried out assuming two different non-Newtonian rheology models Carreau and Ballyk models) and rescaled Newtonian viscosities based on characteristic shear rates to account for the shear-thinning property of blood. The sensitivity of WSS and oscillatory shear index (OSI) were contextualized with respect to the reproducibility of the reconstructed geometry and to assumptions regarding the inlet boundary conditions. We conclude that the assumption of Newtonian fluid is reasonable for studies aimed at quantifying the distribution of WSS-based extrema in an image-based CFD model of carotid bifurcation.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.10a
• /
• pp.181-185
• /
• 2008

In this study, we attempted to quantify the relative importance of assumptions regarding blood rheology. Three patient-specific carotid bifurcation geometries and time-varying flow rates were obtained using magnetic resonance imaging. For each subject, CFD simulations were carried out assuming two different non-Newtonian rheology models (Carreau and Ballyk models) and rescaled Newtonian viscosities based on characteristic shear rates to account for the shear-thinning property of blood. The sensitivity of WSS and oscillatory shear index (OSI) were contextualized with respect to the reproducibility of the reconstructed geometry and to assumptions regarding the inlet boundary conditions. We conclude that the assumption of Newtonian fluid is reasonable for studies aimed at quantifying the distribution of WSS-based extrema in an image-based CFD model of carotid bifurcation.