• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.313-320
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• 1998

Tri-phasic pulsatile flow is the general flow pattern of human circulary system. In emulating the various situation of cardiovascular system, it is essential to make tri-phasic source flow. To emulate tri-phasic pulsatile flow, we used electro-hydronic style LVAD(Left Ventricular Assist Device) with glass phantom and rubber tube. We have selected control parameters and examined the changing effect of each parameter by using Doppler ultrasound. In this experiment, it was shown that the distal compliance and the break time were the major factors to form tri-phasic flow. The results make it possible to emulate and explain the various situation of human vascular system. In this point, this results will be an useful method in the clinic application.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.486-494
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• 2021

The growth of pulsed electromagnetic field (PEMF) therapy and its progress over the years for use in post-operative bone growth has been revolutionary in its effect on bone tissue proliferation and vascular flow. However, further progress in PEMF therapy has been difficult due to lack of more evidence-based understanding of its mechanism of action. Our objective was to review the current understanding of bone growth physiology, the mechanism of PEMF therapy action along with its application in spinal surgery and associated outcomes. The authors of this review examined multiple controlled, comparative, and cohort studies to compare fusion rates of patients undergoing PEMF stimulation. Examining spinal fusion rates, a rounded comparison of post-fusion outcomes with and without bone stimulator was performed. Results showed that postoperative spinal surgery PEMF stimulation had higher rates of fusion than control groups. Though PEMF therapy was proven more effective, multiple factors contributed to difficulty in patient compliance for use. Extended timeframe of treatment and cost of treatment were the main obstacles to full compliance. This review showed that PEMF therapy presented an increased rate of recovery in patients, supporting the use of these devices as an effective post-surgical aid. Given the recent advances in the development of PEMF devices, affordability and access will be much easier suited to the patient population, allowing for more readily available treatment options.

• Korean Journal of Human Ecology
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• v.21 no.1
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• pp.141-149
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• 2012

This study investigates the effects of wear training on blood pressure and blood lipid profiles. For the purpose of this research, 'wear training' refers to the alternating stimulation of temperature while using specific clothing under controlled situations ($18.8{\pm}0.2^{\circ}C$, $38{\pm}3%RH$). The participants alternated between two different garments producing a $1.5^{\circ}C$ difference in the innerest microclimate temperature over a period of 4 weeks. The experiments in this study were conducted in a comfortable environment after sufficient rest. The results were as follows. The systolic blood pressure and mean arterial pressure were lower in the post test than in the pre test (p<.05). The atherogenic index (AI) was also reduced and the LDL-C/HDL-C ratio increased (p<.05) in the post test. These results demonstrated that wear training positively affected improvement in vascular stiffness.

• Korean Journal of Human Ecology
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• v.18 no.1
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• pp.211-221
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• 2009

The study investigated medical treatment features of patients with type 2 diabetes mellitus, their further complications, levels of diet therapy education and the status of dietary compliance. The subjects were patients who came to oriental medicine clinics in Daejon. The percentage of male was 37.5% and female was 62.7% in the subject group's sex distribution. The outbreak of the disease was most common in the age of 50's. Also 40% of the subjects had been suffering for more than 5 years. 35.7% of men and 53.7% of women had family history. All the subjects had further complications, among them hypertension was the most common. Kidney, hepatic, vascular heart diseases were followed. 85.3% of the subjects answered they already had educations about diet therapy. Those educations were given in the public health center, general and private hospitals. 32% of subjects were not practicing diet therapy. The difficulties with which patients can be faced when they take dietary education were exchange(?exchanging?) food and calculating calories. Most of the subjects tend to overlook the importance of dietary habits and show low understanding to diet therapy, which leads to low participation rate of diabetes patients. Based on these results, therefore, we can conclude that diet therapy education to the patients should be more organized and easily practicable for them. To develop educational methods which can draw patients' attention and also be more effective is the most important task.

• Journal of Biomedical Engineering Research
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• v.36 no.5
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• pp.183-190
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• 2015

Invasive blood pressure (IBP) is measured for the patient's real time arterial pressure (ABP) to monitor the critical abrupt disorders of the cardiovascular system. It can be used for the estimation of cardiac output and the opening and closing time detection of the aortic valve. Although the unexplained inflections on ABP make it difficult to find the mathematical relations with other cardiovascular parameters, the estimations based on ABP for other data have been accepted as useful methods as they had been verified with the statistical results among vast patient data. Previous windkessel models were composed with systemic resistance and vascular compliance and they were successful at explaining the average systolic and diastolic values of ABP simply. Although it is well-known that the blood pressure reflection from peripheral arteries causes complex inflection on ABP, previous models do not contain any elements of the reflections because of the complexity of peripheral arteries' shapes. In this study, to simulate a reflection wave of blood pressure, a new mathematical model was designed with four elements that were the impedance of aorta, the compliance of aortic arch, the peripheral resistance, and the compliance of peripheral arteries. The parameters of the new model were adjusted to have three types of arterial blood pressure waveform that were measured from a patient. It was used to find the relations between the inflections and other cardiovascular parameters such as the opening-closing time of aortic valve and the cardiac output. It showed that the blood pressure reflection can bring wide range errors to the closing time of aortic valve and cardiac output with the conventional estimation based on ABP and that the changes of one-stroke volumes can be easily detected with previous estimation while the changes of heart rate can bring some error caused by unexpected reflections.

• Journal of Industrial Convergence
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• v.21 no.3
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• pp.171-179
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• 2023

To investigate the effects of type of exercise on inflammatory factor and vascular endothelial growth factor in middle aged women, we recruited 18 people middle-aged women and they divided into 3 groups (N=6, resistance exercise group, 40-60% of 1RM, N=6 aerobic exercise group, 60-70% of VO2max, N=6, flexibility exercise group, 10-60 sec/sets). The data were compared to the effect of exercise between 50 ~ 60 minutes per a day, 3 day times per week on the body composition, inflammatory factor, vascular endothelial growth factor and vascular compliance in middle aged women. First, in regards to inflammatory factors between groups, a significant difference (p<.05) was identified in the effects of CRP and IL-6 in terms of time (T). Second, regarding vascular endothelial growth factors between groups based on the type of exercise, a significant difference (p<.05) was found in the effects of VEGF's time (T) and the interaction between time and group (TxG). In conclusion, All types of exercise could partially improve inflammatory factors and vascular endothelial growth factors.

• Journal of Biomedical Engineering Research
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• v.17 no.3
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• pp.337-346
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• 1996

The patency of small size vascular grafts is poor, and the blood flow characteristics in the artery graft anastomosis are suspected as one of the important factors influencing intimal hyperplasia. Disturbed flow patterns caused by sixte and compliance mismatch generate unfavorable flow environment which promotes intimal thickening. Tapered vascular yuts are suggested in order to reduce sudden expansion near the anastomosis. The photochromic flow visualization method is used to measure the flout fields in the end-to-end anastomosis model under the carotid and femoral artery flow wave form. The results show that flow disturbance near the anastomosis is diminished in the tapered grafts comparing to the tubular graft. As the divergent ang1e decreases, we can reduce the low and oscillatory wall shear stress zone which is prone to intimal hyperplasia. The flow wave form effects the wall shear rate dis- tribution significantly. The steep deceleration and back flow in the femoral flow wAve form cause low mean wall shear rate and high oscillatory shear index.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.2
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• pp.20-29
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• 2003

A new treatment for coronary artery occlusive disease is being developed in which a shunt or conduit is placed directly connecting the left ventricle with the diseased artery at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Simulation results indicate that in complete LAD occlusion, flow can be returned to approximately 65% of normal if the conduit resistance is equal for forward and reverse flow, increasing to 80% in the limit in which backflow resistance is infinite. Increases in flow rate produced by asymmetric flow resistance are considerably enhanced in the case of a partial LAD obstruction since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle("steal") during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but leads to considerable augmentation when the resistance is asymmetric. These results suggest that an LV-LAD conduit will be beneficial when stenosis resistance(Rst) > 27 PRU if resistance is symmetric.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.133-134
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• 2008

우리나라의 당뇨병 유병률은 경제발전과 식생활의 급속한 서구화로 빠른 속도로 증가하고 있다. 특히 당뇨병은 유병기간이 길수록 여러 합병증을 초래하는데 그 중 하나가 혈관경화증이다. 혈관 경화증은 신체 부위별로 그 진행 속도가 다르다. 광혈류측정법(PPG, photoplethysmogram)은 간편한 혈류량 측정방법으로 PPG 2차 미분 방법을 이용해서 혈관의 경화도를 진단할 수 있다. 이러한 PPG 2차 미분방법을 이용하여 당뇨병환자의 왼손과 오른손의 말초혈관 탄성도 차이를 정상인과 비교해 보았다. 실험결과 당뇨병환자와 정상인의 양 손가자 말초혈관 탄성도의 유의한 차이를 확인 할 수 있었다.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2745-2748
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• 2003

In this paper, we implement the photoplethysmo-graphy system that have three channel pulse wave detects and one channel ECG amplifier. In order to detect the artery state, we measured the pulse waves at different positions, simultaneously. In general, arterial vascular system suffers the decrease of compliance, increase of resistance, and decrease of distensibility through aging. Therefore, we compared and analyzed variation of tile Pulse waves parameter both in time and frequency domains that is concerned with the changes of arterial characteries. And then evaluated the correlation coefficients between the parameters variation and the age group. As the result of experiment, we found that the Parameters have a significant correlation about aging.