• The Journal of the Society of Korean Medicine Diagnostics
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• v.15 no.2
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• pp.159-168
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• 2011

Objectives: The purpose of this study is to develop the pulse wave analysis model with the palpation pressure and the skin effect. Methods: The position of pulse diagnosis was modeled with elastic string system. The skin was modeled with the elastic string, the palpation pressure with tension in the string, and the blood vessel pressure with external force on the string. Using the wave equation in the physics, the simplified pulse model was transformed to the mathematical model. Results: To the verification of the model, the effects of the palpation pressure and the skin effect were tested. Conclusions: There was optimal palpation pressure, describing the exact vessel pressure pattern and maximizing the amplitude of the skin displacement. For the optimal condition, the increased palpation pressure was needed with the increased skin thickness. Therefore, the developed pulse wave analysis model showed the good results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.912-921
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• 1999

Shear stress acting on the arterial wall by blood flow is an important hemodynamic factor influencing blocking of blood vessel by thickening of an arterial wall. In order to study the effects of wall elasticity on the wall shear rate distribution in an artery-divergent graft anastomosis, a rigid and a elastic model are manufactured. These models are placed in a pulsatile flow loop, which can generate the desired flow waveform. Flow visualization method using a photochromic dye is used to measure the wall shear rate distribution. The accuracy of measuring technique is verified by comparing the measured wall shear rate in the straight portion of a model with the theoretical solution. Measured wall shear rates depend on the wall elasticity and flow waveform. The mean and maximum shear rate in the elastic model are lower than those in rigid model, and the decreases are more significant near the end of a divergent tube. The reduction of mean and maximum of wall shear rate in an elastic model are up to 17 percent.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.363-372
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• 2000

The present study investigated flow dynamics of a straight elastic blood vessel under sinusoidal flow conditions in order to understand influence of wall motion and impedance phase angle(time delay between pressure and flow waveforms) on wall shear stress distribution using computational fluid dynamics. For the straight elastic tube model considered in the our method of computation. The results showed that wall motion induced additional terms in the axial velocity profile and the pressure gradient. These additional terms due to wall motion reduced the amplitude of wall shear stress and also changed the mean wall shear stress. Te trend of the changes was very different depending on the impedance phase angle. As the wall shear stress increased. As the phase angle was reduced from 0$^{\circ}$to -90$^{\circ}$for ${\pm}$4% wall motion case, the mean wall shear stress decreased by 10.5% and the amplitude of wasll shear stress increased by 17.5%. Therefore, for hypertensive patients vulnerable state to atherosclerosis according to low and oscillatory shear stress theory.

• Journal of Biomedical Engineering Research
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• v.23 no.4
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• pp.281-286
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• 2002

In this study, blood flow in a carotid artery supplying blood to the human's brain has been numerically simulated to find out how the blood flow affects the genesis and the growth of atherosclerosis and arterial thrombosis. Velocity Profiles and hemodynamic parameters have been investigated for the carotid arteries with three different stenoses under physiological flow condition. Blood has been treated as Newtonian and non-Newtonian fluid. To model the shear thinning properties of blood for non-Newtonian fluid, the Carreau-Yasuda model has been employed. The result shows that the wall shear stress(WSS) increases with the development of stenosis and that the wall shear stress in Newtonian fluid is highly evaluated compared with that in non-Newtonian Fluid. Oscillatory shear index has been employed to identify the time-averaged reattachment point and this point is located farther from the stenosis for Newtonian fluid than for non-Newtonian fluid The wall shear stress gradient(WSSG) along the wall has been estimated to be very high around the stenosis region when stenosis is developed much and the WSSG peak value of Newtonian fluid is higher than that of non-Newtonian fluid.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.6
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• pp.90-97
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• 2010

In order to understand the biomaterial like the blood vessel of artery, there is a need to quantify the biomechanical behavior of the vessel. Using computer-controlled experimental system, the experiment can acquire data such as inner pressure, axial load, diameter and axial gauge length without contacting the specimen. Rubber-liked material which is similar to passive artery was selected as pseudo-biomaterial. Deformations are measured for pressure-diameter curves. The data were collected and stored online to be used in the feedback control of experimental protocols. Finally, the illustrative data obtained from the experimental system were presented and the system shows that strain invariants are controlled to understand the nonlinear elastic behavior of biomaterial which is involved with strain energy function.

• The Journal of the Acoustical Society of Korea
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• v.36 no.5
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• pp.361-369
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• 2017

Hemodynamic information in the carotid artery bifurcation is very important for understanding the development and progression mechanisms of cerebrovascular disease and for its early diagnosis and prediction of the progress. In this paper, we constructed a mock pulsatile blood circulation system using an anthropomorphic elastic vessel of the carotid artery bifurcation and ex vivo pig blood to acquire ultrasound images from blood and vessels synchronized with internal pressure while controlling the blood flow. Echogenicity, blood flow velocity, and blood vessel wall motion from the ultrasound images, and internal blood pressure were extracted over a cycle averaged from five cycles when the pulsatile pump rates are 20 r/min, 40 r/min, and 60 r/min. As a result, respectively, the peak systolic blood flow velocities were 20 cm/s, 25 cm/s, and 40 cm/s, the blood pressure differences were 30 mmHg, 70 mmHg, and 85 mmHg, the arterial walls were expanded to 0.05 mm, 0.15 mm, and 0.25 mm. Time-delayed cyclic variation of echogenicity compared to blood flow and pressure was observed, but the variation was minimal at 20 r/min. Time-synchronized cyclic variations of these parameters are important information for accurate input parameters and validation of the computational hemodynamic experiments which will provide useful information for the development and progress mechanisms of carotid artery stenosis.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.4
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• pp.397-418
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• 1994

Microvascular surgery has been widely used in the clinical field of replantation and reconstructive surgery. Since the last 20 years, microsurgical techniques and instruments have been rapidly developed and the success rate is remarkably increased. But thrombotic occlusion of vessels remains the major reason for clinical failure. The change of vessel wall is the most important factor in thrombus formation. If we can reduce the traumatic changes in the vessel walls during surgery, the success rate can be markedly increased. For this study, femoral arteries and veins of 36 Sprague-Dawley rats with average weights of 300gm were used. The author observed the histological changes and healing process in the anastomostic site after 1 hour, 24 hours, 1, 2, 3 and 4 weeks under light microscopy and scanning electron microscopy. The results were as follows : 1. The patency rate was 100% in femoral arteries and 85% in femoral vein. 2. At the early stages after microvascular anastomosis, the loss of endothelial cell in the vessel walls was observed in the wide area including anastomotic site. In scanning electron microscopic finding the anastomotic site was covered with much fibrin, many red blood cells and some platelets. 3. At 1st week, new endothelial cells were formed toward anastomotic site and at 3rd week, the anastomotic site was completely covered by new endothelial cells. At 4th week, the complete endothelialization over the threads was observed. 4. The media extended from the anastomotic site toward the end of the specimen. At later stages, the extent of media necrosis was markedly decreased. But the media necrosis of anastomotic site was not regenerated till 4th week. 5. Intimal hyperplasia appeared at 1st week and increased till 4th week. The layer consisted of endothelialization the most luminal layers and smooth muscle in the deeper layers. But in veins, the response was less pronounced than in arteries. 6. Foreign body granuloma remained during 4 weeks and aneurysm was observed at 3rd week in artery. In aneurismal wall, media necrosis, loss of elastic lamina and intimal hyperplasia were seen.

• Journal of Korea Multimedia Society
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• v.22 no.11
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• pp.1280-1287
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• 2019

For developing a wireless implantable device to monitoring the artery variation in real-time. The concept of a special vessel variation measurement capacitive sensor is presented in this paper. The sensor consists of two part; main sensor to measuring the arterial variation, and reference sensor is used to improve the accuracy of the capacitance value variation. Before sensor manufacture, a model of the sensor attached on the artery was designed in 3D to conduct in the FEA simulation to validate the validity and feasibility of the idea. The artery model was designed as layered structures and made of collagenous soft tissues with intima inside, followed by the media and the adventitia. Also, a grease layer was designed in the inner of the arterial wall to imitate the clogged arteries. The simulation was divided into two parts; sensor performance test by changing the diameter of the grease layer, and arterial wall tension test by changing the blood pressure. As the simulation results, the capacitance value measured by the proposed sensor is decreased follow the diameter of the grease increased. Also, large elastic deformation of the arterial wall since changing the blood pressure has been observed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1219-1227
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• 2011

Due to recent changes in living conditions, people who suffer from vascular disease have been increasing. As a result, several kinds of procedures to treat diseases of the blood vessels are being carried out and the epidemiological analysis and interpretation is needed. In this paper, the mechanical behavior of blood vessels based on hyperelastic model were evaluated. The stress distributions in the arterial walls subjected to both normal blood pressure and high blood pressure are studied along with different opening angles representing as the effect of the residual stress. As a result, when applied to residual stress effects in blood vessels to act maximum stress compared to as the absence of residual stress effect about 50% stresses can be reduced. When high blood pressure was the normal blood pressure acting on the blood vessel wall that twice stress can be confirmed.

• Journal of Pharmacopuncture
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• v.27 no.1
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• pp.47-52
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• 2024

Phlebotomy, a therapeutic method of bloodletting typically performed using a needle, has a traditional technique known as "Fasd." In this method, blood is extracted by creating a longitudinal incision on a vein (3-5 mm) with a surgical scalpel blade, usually blade No. 11. Due to the incision in the vessel wall, establishing hemostasis is more challenging compared to conventional methods. Hemostasis is usually achieved within minutes after Fasd. We present a case highlighting an uncommon yet significant complication of traditional phlebotomy. A 55-year-old man with no prior medical conditions underwent traditional phlebotomy at an academic traditional medicine clinic. Senior MD-PhD students in Iranian Traditional Medicine, under professor supervision, performed Fasd. A sterile scalpel blade No. 11 was used to create a longitudinal incision of approximately 4 mm on the patient's median basilic vein in the right hand. After removing 400 cc of blood, a pressure dressing was applied to the incision site. Despite attempts such as hand elevation, ice pack application, prolonged direct pressure, and tight elastic bandaging, bleeding from the incision persisted. After an hour of supportive therapy, hemostasis was eventually achieved within a few minutes using burnt cotton dressing (a traditional method for blood hemostasis). Following intravenous hydration, the patient was discharged in stable condition and reported no issues during the one-month follow-up. The traditional phlebotomy (Fasd) carries the risk of serious complications, including uncontrolled and prolonged bleeding. Further research on the efficacy and safety of burnt cotton dressing for controlling hemostasis is recommended.