• Journal of Biomedical Engineering Research
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• v.2 no.2
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• pp.89-102
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• 1981

The recirculating flows which occur in the prosthetic heart valve have been known to cause several diseases in the human body. And the recent studies show that the shear stress at the wall of the artery is also very important factor in the formation of thrombus. And many studies knave been devoted in obtaining more information about the blood flow through the prosthetic heart valve. In this Paper, the steady axisymmetric flow through the Disc-Type Heart Valve is studied by using the numerical method. The geometry of the Disc-Type Heart Valve is simplified, and the flow is assumed to be steady axisymmetric flow. The vorticity transport equation derived from the Wavier-Stoke's equation is used as the governing equation, and the explicit finite difference method is used to obtain the steady state solution. The results for several Reynolds numbers show that the recirculating flow becomes large as the Remolds number increases. Furthermore, it can be shown that the magnitudes of the vorticity and the stresses are also increased with the Reynolds number, but there is only a little change in their configurations of distribution and in their positions of maximum values.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.140-146
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• 2014

Stenosis is the drastic reduction in the cross-sectional area of blood vessel caused by accumulations of cholesterol. It affects the blood flow property and structure from the fluid dynamic point of view. To understand the flow phenomenon more clearly, a particle image velocimetry method is used and the fluid dynamic characteristics in a circular channel containing stenosis structure is investigated experimentally in this study. Different stenotic-structured models made of acrylic material are subjected to a pulsatile flow generated by an in-house designed pulsatile pump. The inner diameter of the tube inlet is 20 mm and the length of reduced area for stenosis ranges between 35mm and 40mm. It is circulated continuously through a circular channel by the pump system. Pressure is measured at four different sections during systolic and diastolic phase changes. The phase-averaged velocity field distribution shows a recirculation regime after the stenotic structure. The effects of the stenotic obstructions are found to be more severe when the aspect ratio is varied.

• Korean Journal of Veterinary Research
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• v.39 no.1
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• pp.169-176
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• 1999

The purposes of this study were to set up the method of the natural killer(NK) cell activity assay using the flow cytometer and to examine the characteristics and distribution of the NK cell during rat hepatocarcinogenesis. Forty five male 6 week-old specific pathogen free(SPF) Sprague-Dawley rats were randomly divided into three groups. Group I was the non-treated control and given normal diet and water. Group II was treated with diethylnitrosamine(DEN, 200mg/kg, i.p.) and partial hepatectomy. Group III was treated with DEN, partial hepatectomy and 0.05% phenobarbital sodium in water from 3 to 16 weeks. All animals were examined the morphology of the large granular lymphocyte(LGL), the LGL percent of the total lymphocytes and the LGL conjugation rate with YAC-1 cell in peripheral blood, spleen and liver. Moreover, activity of the LGL isolated from peripheral blood lymphocytes was determined using the flow cytometer. As results, LGL were observed in the peripheral blood, spleen and liver. LGL were observed the relatively faintly staining basophilic cytoplasm with granules, and eccentric, often kidney-shaped nuclei in Giemsa stain. Its size was $11{\sim}13{\mu}m$. LGL percentage of the isolated lymphocytes in peripheral blood, spleen and liver were 1.8~2.3%, 1.3~1.4% and 0.87~0.99%, respectively. LGL conjugation rate with YAC-1 cell was shown to be peripheral blood(9.3~10.3 %) > spleen(7.7~8.7%) > liver(5.6~7.0%). The activity of the LGL isolated from peripheral blood lymphocytes in Group I, II and III was 33.7%, 30.5% and 35.4%, respectively. However, all values were not significantly between groups.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.5
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• pp.509-519
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• 2013

Through the study on judgment of Body form and settle Energy flow(立形定氣) before diagnose the patients, the results are as follows. The observation of the body form is to determine prosperity and deficiency of each internal organ. It is necessary to distinguish Body form loss(形脫) and Body form fullness(形充). Fat man(肥人), Thin man(瘦人), Creamy man(膏人), Muscular man(肉人), Small Fat man(脂人) are discriminated by fat distribution, fat content, and muscle mass. The observation of the body form means the observation of structure disorder, color change, develop part at body, head and face. The observation of the body form that is to determine prosperity and deficiency of each internal organ is from the limited knowledge of the anatomy. The observation of face color is considered by blood perfusion, blood oxygenation and accumulation of carotinoid, bilirubin and change of melanin in the facial skin. The prosperity and the deficiency of energy flow is considered by symptom combined with growth (<40 years) and aging (>40 years). The prosperity of energy flow includes the anger, anxious emotion and the deficiency of energy flow includes the fear, depressive emotion. The breathing type is expiratory exhalation like asthma patients in the prosperity of energy flow. The deficiency of energy flow is weakness to overcome the disease. The prosperity and the deficiency of energy flow are considered by body metabolic ratios (Basal metabolic Rate: BMR, Resting metabolic rate: RMR, Physical activity ratios: PASs). Development of subcutaneous fat is good in the person of prosperous energy flow. The person of prosperous energy flow is hard to overcome to heat weather than cold weather. The person of deficiency of energy flow has tendencies of low blood pressure, insufficiency of blood flow in the peripheral and being shocked. The person of deficiency of energy flow has tendencies of chronic fatigue syndrome or automatic nerve disorder. If the patient who has deficiency of energy flow has severe weight loss should be checked for the presence of disease. The observation of small and large of bone is to check the development and disorder of bone growth and aging. The observation of thickness and weakness of muscle is to check the development of muscle, particularly biceps, gastrocnemius, and rectus abdominal muscle. The observation of thickness and weakness of skin is to check the ability of regulating body temperature by sweating.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.552-557
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• 2007

Due to the recent improvement of living standard of residential buildings, the requirements of the thermal comfort and energy saving in heating system have been raised. The radiant floor heating system has been widely used as a residential heating method, which has been modernized to use hot water running into the tubes embedded in the floor structure. The uniform flow distribution is very important factor for a radiant floor heating system such as a blood vessel system in human body. Therefore, it is necessary to investigate the operating characteristics to develop an optimal radiant floor heating system. In this study, numerical analyses were carried out, using a commercial CFD code, FLUENT, to obtain the velocity distribution under steady, three-dimensional, standard k-$\varepsilon$ model and no-slip condition. Results are graphically depicted with various parameters.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.24-31
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• 2003

As endothelial cells are subject to flow shear stress, it is important to determine the detailed velocity distribution in microvessels in the study of mechanical interactions between blood and endothelium. This paper describes a velocity field of the arteriole in the rat mesentery using an intravital microscope and high-speed digital video system obtained by a highly accurate PIV technique. Red blood cells (RBCs) velocity distributions with spatial resolutions of $0.8{\times}0.8{\mu}m$ were obtained even near the wall in the center plane of the arteriole. By making ensemble-averaged time-series of velocity distributions, velocity profiles over different cross-sections were calculated for comparison. The shear rate at the vascular wall also evaluated on the basis of the ensemble-averaged profiles. It was shown that the velocity profiles were blunt in the center region of the vessel cross-section while they were steep in the near wall region. The wall shear rates were significantly small, compared with those estimated from the Poiseuille profiles.

• The Korean Journal of Pharmacology
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• v.5 no.2
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• pp.141-148
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• 1969

The direct effect of isoproterenol on renal function, when given intravenously, is usually obscured by its potent hypotensive action. To obviate the latter action, isoproterenol was infused directly into one renal artery of the dog, the other kidney serving as a control for the general action. And following results were obtained. In the first series of experiments, the directic action of isoproterenol was ascertained. $1.0\;{\mu}g/kg/min$. reduced on both kidneys the urine flow, clearances of PAH and creatinine, as well as the amount of sodium excreted, but the effect was weaker on the experimental side than on contralateral side. With $0.1\;{\mu}g/kg/min$., two cases among 6 experiments showed marked diuresis, two cases no apparent effect, and another two marked antidiuresis on the experimental kidney, whereas the contralateral kidney exhibited antidiuresis in all cases. Further reducing the dose unmasked the diuretic action on the ,experimental kidney. In another series, the effects of isoproterenol on the blood flow distribution within the kidney and on sodium concentration gradient within the kidney tissue were observed. $0.05\;{\mu}g/kg/min$ isoproterenol markedly increased the medullary plasma flow and slightly increased total renal plasma flow and glomerular filtration rate, along with concomitant increase in the amount of sodium excreted and osmolar clearance, and decrease in reabsorption of free water. Sodium concentration gradient markedly decreased in the experimental kidney, reaching 2/3 of the value observed in the contralateral kidney at the papilla. It is thus concluded that isoproterenol exerts a diuretic action, when infused directly into a renal artery, and the mechanism of the action rests on its hemodynamic action, substantiated as the increase in glomerular filtration and in the medullary blood flow, resulting in washout of hyperosmolality produced by the coutercurrent multiplier system.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.11a
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• pp.99-113
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• 1996

Taurine, a ${\beta}$-amino acid, plays an important role as a neuromodulator and is necessary for the normal development of the brain. Since de novo synthesis of taurine in the brain is minimal and in vivo studies suggest that taurine does not cross the blood-brain barrier, the blood-cerebrospinal fluid (CSF) barrier is likely to play a role in taurine transport between the central nervous system and the systemic circulation. Therefore, we examined in vivo elimination of taurine from the CSF in the rat to characterize in vivo kinetics of elimination for taurine from the CSF is consistent with the in vitro study. Using a stereotaxic device, cannulaes were placed into the lateral ventricle and the cisterna magna of the rat. Radio-labelled taurine and inulin (a marker of CSF flow) were injected into the lateral ventricle, and the concentrations of the labelled compounds in the CSF were monitored for up to 3 hrs in the cisterna magna. The apparent clearance of taurine from CSF was greater than the estimated CSF flow (p<0.005), indicating that there is a clearance process in addition to the CSF flow. Taurine distribution into the choroid plexus was at least 10 fold higher than that found in other brain areas (e.g., cerebellum, olfactory bulb and cortex). When unlabelled taurine was co-administered with radio-labelled taurine, the apparent clearance of the labeled taurine was reduced (p<0.01), suggesting a saturable disposition of taurine from CSF. Distribution of taurine into the choroid plexus, cerebellum, olfactory bulb and cortex was similarly diminished, indicating that the saturable uptake of taurine into these tissues is responsible for the non-linear disposition. A pharmacokinetic model involving first order elimination and saturable distribution described these data adequately. The Michaelis-Menten rate constant estimated from in vivo elimination study is similar to that obtained in the in vitro uptake experiment Collectively, our results demonstrate that taurine is transported in the choroid plexus via a taurine is cleared from the CSF via a saturable process. This process may be functionally relevant to taurine homeostasis in the brain.

• Journal of The Korean Association For Science Education
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• v.27 no.5
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• pp.379-393
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• 2007

The purpose of this article is to analyze the conceptual change of nine 11th graders after implementing the model-based instruction of blood circulation by multidimensional framework, and to find some implications about teaching strategies for improving conceptual understanding. The model-based instruction consisted of 4 periods: (1) introduction for inducing students' interests using an episode in the science history of blood circulation, (2) vivisectional experiment on rats, (3) visual-linguistic model instruction using the videotape of heartbeat, and (4) modeling activity on the path of blood flow. Based on the data from pre-test, post-test and interviews, we classified students' models on the path of blood flow, and investigated their ontological features and the conceptual status of blood circulation. Most students could describe the path of blood flow and the changes of substances in blood precisely after the instructions. However, the modeling activity were not sufficient to improve students' understanding of the mechanisms of the blood distribution throughout various organs and the material exchanges between blood and tissues. From the interview of 9 students, we acquired informative results about conceptual status elements that were helpful to, preventing from, or not used for students' understanding. It was also found that conceptual status of students depended on the ontological categories into which students' conceptions of blood circulation fell. The results of this study can help design the effective teaching strategy for the understanding of concept of the equilibrium category.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2935-2940
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• 2007

To diagnose circulatory diseases in the viewpoint of hemodynamics, we need to get quantitative hemodynamic information of blood flows related with the vascular diseases with high spatial resolution of tens micrometer and high temporal resolution in the order of millisecond. For investigating in-vivo hemodynamic phenomena, a new diagnosing technique combining medical radiography and PIV method was newly proposed and developed. This angiographic PIV technique consists of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulses of X-ray, and a synchronizer. The feasibility of the angiographic PIV technique was tested and quantitative flow velocity field distribution of a flow inside an opaque conduit was acquired by the developed system. It can be used for measuring flow phenomena of nontransparent fluids inside opaque conduits.