• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1869-1875
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• 2001

The paper presents computational and flow visualization results on a centrifugal blood pump. 4 impeller designs were tested at a rotational speed of 2000 rpm using blood analog as working fluid. All impellers have seven blades but of different geometry (Impellers A3, A4, B2 and R7). Flow visualization within the impeller passages was conducted using an image de-rotation system. A pair of large scale vortices was found within the blades of impeller R7 while a single vortex was found in most of the passages of backward facing impellers (Impellers A3, A4 and B2). To establish the effects of blade geometry on blood cells, CFD was used to simulate the blade to blade flow to provide an estimate of the maximum shear stress. The results showed that though most of the stresses within the blade passages are below a threshold level of 150 N/m$^2$for extensive erythrocyte damage to occur, there are some regions near to the leading edge of the pressure side where the shear stresses a abode threshold level.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.1
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• pp.109-118
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• 2022

Purpose : The study to verify the effectiveness of the Soomchi combined marine healing program by analyzing the physical composition of the subjects, their blood lipids, and the effects of the program on their lung health-related variables, and heart rate variability variables. Methods : In the experiment, the Soomchi combined marine healing program was conducted for 5 hours a day, 5 days a week. on 15 participants. The results of their body composition, blood lipids, lactic acid, blood pressure, PEF, FEV1 and maximum oxygen intake were analyzed before and after the subjects completed the Soomchi program. For the statistical analysis, the mean and standard deviation (M±SD) of each variable were calculated using SPSS version 20 and an independent t-test was conducted to test for the amount of change in the participants before and after the Soomchi combined marine healing program. All significant levels were set to α=.05. As a result of the experiment Results : First, no statistically significant differences were found in the changes in body composition after the 5-day combined marine healing program was completed. Second, regarding the changes in blood component after the program was conducted, statistically significant differences were found in the lactic acid (p<.05). That is, the experimental group showed a significant decrease in lactic acid after the program whereas the control group showed a significant increase. Third, systolic blood pressure decreased significantly and while in PEF and FEV1 increased significantly in the experimental group after the program. Fourth, the LF of the control group significantly decreased after 5 days. Conclusion : After the Soomchi Lung Health Ocean Healing Program, positive physical changes were observed in the lung health variables and heart rate variability of the participants.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.121-126
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• 2003

The purpose of this work was to assess and quantify whether the beneficial effects in long-term gas exchange at exciting frequency were obtained at different frequencies as well and then to develop a vibrating intravascular lung assist device(VIVLAD), for Patients suffering from acute respiratory distress syndrome(ARDS) or chronic respiratory problems. We investigate the optimal condition of the frequency band excited with new vibrator at state of limit hemolysis when blood hemolysis came to through a membrane vibration action. The experimental design and procedures were given for a device used to assess the effectiveness of membrane vibrations. Quantitative experimental measurements were performed to evaluate the performance of the device . and to identify membrane vibration dependence on blood hemolysis. We developed an analytical solution for the hydrodynamics of flow through a bundle of sinusoidally vibrated hollow fibers that is used to provide some insight into how wall vibrations might enhance the performance of the VIVLAD. In the result, it was measured that the effect of various excited frequencies in gas transfer rate and hemolysis from the maximum gas transfer rate at no vibration when the maximum gas transfer rates showed at module type 6, module type 6 consisted of 675 hollow fiber membranes The maximum oxygen transfer rate was caused by the occurrence of maximum amplitude and transfer of vibration to hollow fiber membranes when it was excited by the frequency band of 7Hz at each blood flow rate. because this frequency became the End mode resonance frequency of the flexible in blood flow. Also, when module type 6 was excited at an excited frequency of 7Hz. blood hemolysis was low. Therefore, we decided that the limit of hemolysis frequency is 7Hz . because maximum amplitude occurred at this frequency.

• Journal of Korean Academy of Nursing
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• v.23 no.3
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• pp.431-452
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• 1993

This study was done to determine the effect of music therapy on stress and quality of life in patients undergoing hemodialysis. The research design was a nonequivalent control group pre -post test design. The subjects consisted of 21 patients who received hemodialysis in two hospitals located in Kwang Ju. The fourteen receiving treatment in one hospital were assigned to the experimental group and the seven in the other hospital to the control group. Data were gathered from December 14, 1992 to January 16, 1993 through questionnaires and physiological measurement. Data were analyzed by the SAS package using frequency, t-test, paired t-test and Pearson Prod uct - Moment Correlation Coefficient. The results of this study are summarized as follows ; 1. There were no significant differences between the two groups on stress scores and quality of life scores before the treatment. 2. The mean score on the psychological stress scale for the patients undergoing hemodialysis was 2.48 out of a maximum mean score of four, the items with high stress scores were “feeling of weakness and annoyed by everything”, “limitation of food”, “limitation of fluid”, “change in skin color” in that order. The psychological category showed the highest stress score followed by developmental, scoioeconomic and physiological stress categories in that order. 3. In the experimental group, post - test diastolic blood pressure decerased significantly(t=3.24, p=0.0064), but in the control group pre and post - test diastolic blood pressure were not different. 4. There was no difference between the two groups on the pre and post -test psychological stress scores or the depression scores. 5. The mean score of quality of life for patients undergoing hemodialysis was 2.75 out of a maxi-mum mean score of five. The category of ‘emtional state’ showed the highest score followed by ‘self - esteem’, ‘physical state and function’, ‘economic life’, ‘relationship with neighbors’ and ‘family relationship’ categories in that order. There was no significant difference in the pre and post - test quality of life scores between the two groups. 6. Hypothesis 1 that patients undergoing hemodialysis who received music therapy would have less stress than patients undergoing hemodialysis who did not receive music therapy is divided into two sub - hypotheses. 1) The first sub-hypothesis that patients undergoing hemodialysis who received music therapy would have less physiological stress than patients undergoing hemodialysis who did not receive music therapy was partly supported. Among three physiological stress indices (pulse, systolic blood pressure, diastolic blood pressure), only diastolic blood pressure decreased significantly after the treatment in the experimental group. 2) The second sub-hypothesis that patients undergoing hemodialysis who received music therapy would have less psychological stress than patients undergoing hemodialysis who did not receive music therapy was not supported. Psychological stress score and depression score were not significantly different before and after the treatment. 7. Hypothesis 2 that patients undergoing hemodialysis who received music therapy would have a higher quality of life score than patients undergoing. hemodialysis who did not received music therapy was not supported. There were no significant changes in the quality of life scores before and after the treatment.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.5
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• pp.25-31
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• 2014

Bioelectrical Impedance Analysis(BIA) is a widely used method for estimating body composition changes which is a non-invasive, inexpensive, safety and reproductive method. We studied the bioimpedance change and the distinction of blood pressure according to body posture and conducted three kinds of experiments: the real-time bioimpedance measurement, the simulation using equivalent circuit model and the blood pressure measurement. Bioimpedance is measured during 4 minutes at the multi-frequency(1 kHz, 10 kHz, 20 kHz, 50 kHz, 70 kHz, 100 kHz). From the experiment results, the changes in body postures result in changes of resistance and reactance, with an average rapid increase of body impedance when going from standing, sitting to supine. Specially, the laying resistance on average was 16.49% higher than supine resistance at 50 kHz and the laying reactance measurement was also 26.05% higher than sitting reactance at 1 kHz. Blood pressure in standing posture was higher than those in other postures both in maximum($125.14{\pm}12.30$) and in minimum($75.57{\pm}10.31$). The results of BIA and blood pressure in this study will be contributed to the research on acute illness, extreme fat, and body shape abnormalities.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.138-142
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• 2016

A pulse measurement by tonometry provides useful information for diagnosis, including not only blood pressure and heart rate but also parameters for estimating a condition of the cardiovascular system. Currently, various pulse measurement devices based on the tonometry have been developed. A reliability of these devices is determined by a positioning technic between the sensor and the blood vessel and a controlling technique of the pressurization level. An angle of the sensor for the pulse measurement seems to be highly related with a measured signal, however, the objective studies for this issue have been not published. In this paper, the variation of the pulse signals by tonometry direction was experimentally assessed according to the angle of the sensor. In order for guaranteeing the repeatability of the experiment, we used a pulse generator device, which can generate human pulse signal by using silicon tube and fluid pump, and developed a structure for precise adjustment of the angle and the pressurization level of the sensor. The angle of the sensor was acquired by an inclinometer, which was attached at the opposite side of the sensor. As results, a coefficient of variation (CV) of a maximum amplitude (MA) of the pulse wave was largely increased over the angle range of $-9{\sim}9^{\circ}$. Furthermore, the changes of the pulse shape showed different aspects according to the sign of the angle tilted along the blood vessel. It is expected that the results of this study can be helpful for developing more precise pulse measurement devices based on the tonometry and applying in clinic.

• The Korean Journal of Physiology
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• v.13 no.1_2
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• pp.29-34
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• 1979

The present study was undertaken to investigate depressor action of tannic acid and the mechanism underlies it in the rabbit. The changes in arterial blood pressure were studied after intravenous administration of tannic acid in normal rabbits and the animals pretreated with atropine, propranolol, dibenamine, and hexamethonium. The results obtained were as follows; 1) Following administration of 1.5 mg/kg, 3.0 mg/kg, and 5.0 mg/kg of tannic acid into rabbits the maximum depressor responses observed were $12.0{\pm}0.9\;mmHg$, $23.4{\pm}1.0\;mmHg$, and $34.0{\pm}1.8\;mmHg$ respectively and generally depressor responses increased in proportion to dosage of tannic acid. 2) Since there were no changes in depressor responses to tannic acid in animals pretreated. separately with atropine, propranolol, dibenamine, and hexamethonium, the depressor responses appeared to be resulting from direct vasodilator action of tannic acid on the vascular smooth muscle. Comparing tannic acid and acorn extract in their mechanisms of depressor responses, it is strongly indicated that in acorn there might exist another depressor substance. 3) After administration of large doses of tannic acid, in addition to respiratory changes, the mean arterial blood pressure decreased markedly and was never recovered throughout the experiment. comma Therefore it is also suggested that the lethal action of tannic acid resides in a drastic decline of arterial blood pressure and in respiratory changes as well.

• Journal of Chest Surgery
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• v.20 no.2
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• pp.223-229
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• 1987

Doppler echocardiography provides valuable information regarding prosthetic heart valve function rather than structure. There are three methods of expressing the severity of mitral valve obstruction: the transvalvular pressure gradient, effective valve area, and pressure half-time. Of these, the transvalvular pressure gradient [~p] can be determined by the measurement of maximum transvalvular blood flow velocity [V] according to the modified Bernoulli`s equation [gp=4V*]. Eleven patients, who underwent mitral valve replacement with Duromedics mechanical prostheses, and 17 normal persons were investigated. There were significantly higher calculated pressure gradients in prosthetic than normal mitral valves [9.*10*2.22mmHg-vs-3.26*0.99mmHg:p<0,01], and there was a inverse relationship between pressure gradient and prosthetic valve size [11.17*0.%mmHg in size 27mm and 29mm -v- 7.38*1.12mmHg in size 31mm and 33mm; r=0.85, p<0.01] The noninvasive Doppler technique should be useful in the diagnosis of prosthetic valve obstruction.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.5
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• pp.493-504
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• 2008

This paper presents a computation of nonlinear elastic strains that may occur in the leaflet of the Edwards MIRA mechanical heart valve by the applied high blood pressure using the finite element analysis methodology. By adopting numerical analysis techniques of the commercial finite element analysis code, NISA, structural analyses of the Edwards MIRA mechanical heart valve are performed for the slight variation of leaflet thickness to get the elastic strains occurring in the leaflet while the high blood fluid pressures are applied to the leaflet surface in order that the maximum stress occurring in the leaflet may be less than the yield stress of the leaflet material(Si-Alloyed PyC). And so, only the geometric non-linearity is assumed because large geometric nonlinear elastic strains are expected rather than material nonlinear strains due to the applied high blood pressure. Computed linear and nonlinear elastic strains are compared to make sure the non-linearity of the computed elastic strain. The comparison result shows that large elastic strains occur clearly in the very thin leaflets as high blood pressures are applied. However, only the linear elastic strains occur for low blood pressures, and also for thick leaflets even for the high blood pressures. Hence the nonlinear structural analysis is very required in the structural design of a mechanical heart valve.

• Journal of Society of Preventive Korean Medicine
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• v.3 no.1
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• pp.125-145
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• 1999

The effects of Wang-ttum, Magnetic Water, Magnetic field and Sibjeondaebotang on hemodynamics in sleep deprivation were studied. The results as follows; 1. In case of Wang-ttum operated group, significant changes were observed at 12 p.m., 2 a.m., 4 a.m. in maximum blood pressure for the first and second overnight stay and at 2 a.m. for the third and, respectively, average blood pressure at 12 p.m., 2 a.m. for the 1st and 2nd overnight stay, minimum blood pressure at 10 p.m.. 12 p.m.. 2 a.m. for the 1st overnight stay and at 10 p.m., 12 p.m. for the 2nd and at 12 p.m. for the 3rd, pulse rate at 12 p.m., 2 a.m., 4 a.m., 6 a.m., for 1st and 2nd and at 2 a.m., 4 a.m. for the 3rd and 4th, TP-KS at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and 2nd and at 2 a.m., 4 a.m., 6 a.m. for the 3rd, PRP at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and 2nd and at 12 p.m., 2 a.m., 4 a.m. for the 3rd and at 2 a.m., 4 a.m. for the 4th, TPR at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. from 1st to 4th overnight stay. 2. In case of taking magnetic water group, significant changes were observed at 2 a.m., 4 a.m. in pulse rate for the 1st overnight stay and, respectively, PRP at 2 a.m. for the 1st, TRP at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and 4th. 3. In case of attaching magnet group, TPR was significantly observed at 10 p.m. for the 1st overnight stay. 4. In case of medicating Sibjeondaebotang group, significant changes were observed at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. in maximum blood pressure for the 1st and 2nd overnight stay and at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 3rd and at 2 a.m., 4 a.m., 6 a.m. for the 4th and, respectively, average blood pressure at 10 p.m., 12 p.m. for the 1st and 2nd and at 10 p.m. for the 3rd and 4th, minimum blood pressure at 10 p.m., 12 p.m. from 1st to 4th, pulse rate at 2 a.m., 4 a.m., 6 a.m. from 1st to 3rd and at 2 a.m., 4 a.m. for the 4th, TP-KS at 10 p.m., 12 p.m., 2 a.m., 4a.m., 6 a.m. for the 1st and at 10 p.m., 2 a.m., 4 a.m., 6 a.m. for the 2nd and at 2 a.m., 4 a.m., 6 a.m. for the 3rd and at 6 a.m. for the 4th, PRP at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 1st and at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 2nd and 3rd and at 12 p.m., 2 a.m., 4 a.m., 6 a.m. for the 4th, TPR at 10 p.m., 12 p.m., 2 a.m., 4 a.m., 6 a.m. from 1st to 4th. As mentioned obove, the effects of Wangttum and Sibjeondaebotang on hemodynamics in sleep deprivation were observed both the impulse of SIM-YANG and mutual function of QI-HYOL. The effects of Magnetic water and Magnetic field were observed the side of mutual function of QI-HYOL.