• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.425-434
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• 2005

In order to analyze pulsating flows in elastic blood vessels, a method based on the ALE concept and finite volume method was reformed and modulated to include wall motion of elastic vessels and impedance phase angle(phase difference between wall motion and blood flow). Our study indicated wall shear rates(WSR) were significantly influenced by the wall motion and the impedance phase angle. For larger wall motion more than $5{\%},$ the computed WSR started to deviate from the results of the perturbation theory that assumed smaller wall motion. The study showed that oscillatory shear index increased as the impedance phase angle became more negative like $-70{\circ}\;or\;-80{\circ}$ due to reduced mean WSR and increased amplitude of WSR. This result indicated that hypertensive patients are more vulnerable to atherosclerosis than normal persons because of the role of more negative impedance phase angles usually observed in these patients.

• 한국체육학회지인문사회과학편
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• v.54 no.1
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• pp.535-544
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• 2015

This study was performed to determine the effect of low-intensity resistance training with blood flow restriction (BFR) on muscle volume and strength in elderly women. Sixteen elderly women (70.9±4.6 years) were divided into low (30% 1RM) and high (75% 1RM) intense resistance training groups. Tourniquet cuff (Zimmer, Germany) for BFR was applied only to the right leg during the training period. All subjects performed unilateral leg press, leg extension and leg curl (3 sets×12 repetitions) for 10 weeks (2d/wk). Blood pressure was increased from 110 to 240 mmHg during the training period at the most proximal region of exercised leg. Muscle volume and cross-sectional area (CSA) were measured by MRI and body composition was monitored by dual-energy X-ray absorptiometry (DEXA) and isokinetic muscular strength were analyzed in both legs. The quadriceps CSA (15.2%, p<.001) and muscle volume (13.8%, p<.001) were increased in high-intense trained leg with BFR and the increased rate was highest among groups. The quadriceps CSA (9.8%, p<.001) and muscle volume (6.9%, p<.001) were increased in low-intensity training group with BFR and their increased rates were higher than control groups. The strength by exercise training was significantly improved in all groups and tended to be higher in BFR groups. These results demonstrate low-intensity resistance training with blood flow restriction could be an effective way to improve muscle volume and strength in elderly women.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1615-1620
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• 2005

We present a novel flow-rate independent cell counter using a fixed control volume between double electrical sensing zones. The previous device based on the single electrical cell sensing in a given flow-rate requires an accurate fluid volume measurement or precision flow rate control. The present cell counter, however, offers the flow-rate independent method for the cell concentration measurement with counting cells in a fixed control volume of $22.9{\pm}0.98{\mu}{\ell}$. In the experimental study, using the RBC (Red Blood Cell), we have compared the measured RBC concentrations from the fabricated devices with those from Hemacytometer. The previous and present devices show the maximum errors of $20.3\%\;and\;16.1\%$, which are in the measurement error range of Hemacytometer (about $20\%$). The present device also shows the flow-rate independent performance at the constant flow-rates ($5{\mu}{\ell}/min$ and $10{\mu}{\ell}/min$) and the varying flow-rate (4, 2, and $4{\mu}{\ell}/min$). Therefore, we demonstrate that the present cell counter is a simple and automated method for the cell concentration measurement without requiring an accurate fluid measurement and precision flow-rate control.

• Journal of Oral Medicine and Pain
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• v.40 no.1
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• pp.10-16
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• 2015

Purpose: Pilocarpine has the effects on improvement of salivary flow and subjective symptoms for xerostomic patients. Because of unwanted side effects following its systemic administration, topical pilocarpine has been paid attention as an alternative. This study aimed to investigate effects of pilocarpine solution as mouthwash on salivary flow and adverse effects compared to systemic administration of 5 mg pilocarpine tablet in healthy subjects. Methods: The study was a double blind, placebo-controlled, crossover clinical trial. Five milligrams pilocarpine tablets, 4 mL of 2% pilocarpine solution and placebo solution were given to 12 healthy volunteers (6 males and 6 females) in a predetermined order with wash-out period of at least two days and unstimulated whole saliva was collected before and after administration of each drug. Blood pressure and pulse rate was also measured and subjective effect and potential side effects were evaluated by a self-administrated questionnaire. Results: Systemic (5 mg tablet) and topical (2% solution) use of pilocarpine significantly increased salivary flow rate in healthy subjects compared to placebo (p<0.001). In both the pilocarpine solution and tablet groups, salivary flow rates at 120 minutes after administration remained increased. Subjective effect on salivation was the largest in the pilocarpine tablet group, followed by the pilocarpine solution group (p<0.05). There was no significant difference in blood pressure and pulse rate after administration of all three drugs. Fewer side effects reported in the pilocarpine solution group than in the tablet group. Conclusions: Two percents pilocarpine solution as mouthwash increases salivary flow rate, definitely superior to placebo solution and comparable to pilocarpine tablet, with fewer side effects in healthy subjects. It indicates a possibility of pilocarpine solution as a useful alternative of pilocarpine tablets for the xerostomic patients with systemic diseases.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.3
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• pp.415-427
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• 1993

The purpose of this study was to evaluate the thermoregulatory responses to postures under different environmental conditions and to obtain the basal information for standard clothing weight, indoor climates, and working condition. Two adult female (22.5yrs, 46kg) were participated in this study. The experimental conditions were divided into three groups ; 1) comfort($27{\pm}1^{\circ}C$, $60{\pm}10%$), 2) hot($34{\pm}1^{\circ}C$, $60{\pm}10%$), and 3) cold($21{\pm}1^{\circ}C$, $50{\pm}10%$) condition. The postures performed were as follows; standing, sitting on the chair, sitting on the floor, and supine on the floor. At each condition, subjective sensations, 12 points skin temperature, rectal temperature, total and local sweat rate, pulse rates, blood pressure, skin blood flow rate were measured. The results were as follows : 1. Rectal temperature was high significant among groups in order of supine, sitting on the floor, sitting on the chair, standing posture(p<0.01). 2. Skin temperature was high in part of contact with the surface of the floor or wall and the effect of posture was greater in peripheral temperature than torso temperature. Sitting on the chair and sitting on the floor posture showed higher peripheral temperature than standing and supine posture. And peripheral temperature was lower in supine posture than any other postures. 3. Total and local sweat rate were decreased in order of standing, sitting on the chair, sitting on the floor, supine posture. 4. Pulse rate and disastolic blood pressure were higher in standing posture than supine posture, and there was significant difference between two postures(p<0.001). 5. Blood flow rate of thigh was high in sitting on the chair and sitting on the floor posture and low in standing posture. Blood flow rate of leg was low in standing posture significantly(p<0.01). 6. In comfort and hot condition, temperature sensation and comfort sensation were higher in standing posture and lower in supine posture than any other postures. In cold condition, temperature sensation was lower and comfort sensation was higher in standing and supine posture than any other postures. And supine posture was appeared positive in hot condition and negative in cold condition. From this study, we confirmed the effects of posture on human thermoregulatory responses. Results indicate that even under same conditions and clothing weight, the insulation of clothing will be different to postures.

• Progress in Medical Physics
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• v.14 no.2
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• pp.141-148
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• 2003

The purpose of this study is to evaluate the distribution of clusters and blood flow rate in ADHD SPECT brain blood flow images of children using statistical parametric mapping (SPM99). We studied 64 ADHD children (4-15 y, $8.03{\pm}2.57$ y. male/female:52/12) and compared them with a control group of 12 children (6-l7 y, $9.42{\pm}3.37$ y, male/female:8/4). We injected blood flow tracer $^{99m}Tc$-ethylcysteinate dimer (ECD) as a rCBF agent and took blood flow images after 30 min. by SPECT camera. In the case of hyperperfusion of rCBF in the ADHD group, we found 3 clusters clearly separated at the cingulate gyrus, Rt.cerebral occipital lobe and Lt.cerebellar post. lobe, on probability level 0.05 (P<0.05). Thirty-six ADHD patients with average hyperfusion rates between 18.72-19.30% in each cluster had more increase in blood flow than the average perfusion rate at the Rt. cerebral occipital lobe. These levels were influenced by P-value. In the case of hypoperfusion in the ADHD children, 4 decreased clusters on Lt. and Rt. cerebral frontal lobe, Lt. cerebral claustrum and Rt. cerebral, sup. temporal gyrus at P<0.01 can be seen. The average hypoperfusion rates for the ADHD children were 18.41-18.69% in each cluster, which showed more hypopefusion than the average perfusion rate at the Lt. Cerebrum inf. Frontal gyrus. The perfusion rates and the number of patients were not affected by P-value. The result of this study shows significant hyperpefusion clusters at the probability level of P:0.05 and hypoperfusion clusters at P:0.01. The number of ADHD patients in each clusters and the perfusion rate were not affected by P-value.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.2
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• pp.342-353
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• 2020

The purpose of this study was to evaluate far-infrared clothing (FIR condition) with non-far-infrared clothing (Control condition) to assess the effects of FIR on thermo-physiological responses. Eight young healthy males (23.0±2.3 yr, 176.5±3.7 cm, and 69.0±4.3 kg) participated in this experimental trial, which consisted of a 20 min rest followed by a 40 min walk (4.0 km·hr^-1) and a 20 min recovery at 20℃ with 50%RH. The results showed that finger skin blood flow and mean skin temperature were significantly higher for the FIR condition than the control during exercise and recovery (p<.001). Clothing microclimate temperature of the FIR condition was 0.5℃ higher on the back (p=.001) and 0.4℃ higher on the thigh (p=.015) during recovery. Clothing microclimate relative humidity of the FIR condition was 13% higher on the chest (p=.006) and 19% higher on the back (p<.001) during exercise than control. Subjects felt warmer and more comfortable in the FIR condition than in the control (p<.05). Perceived skin wettedness (%BSA) was less in the FIR condition than in the control (p=.001). These results indicate that ceramic-embedded clothing had significant effects on thermoregulatory responses for light activity in an indoor environment.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.382-392
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• 2023

Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

• Journal of Chest Surgery
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• v.4 no.2
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• pp.69-80
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• 1971

Total body perfusion using Rygg-Kyvsgaard Heart-Lung-Machine, Mark IV, Polystan was attempted in the dogs by the hemodilution method with total prime of buffered Hartman's solution and under hypothermia. The first of all, the functions of Rygg--Kyvsgaard Heart-Lung-Machine and the effects of the hemodilution perfusion by buffered Hartman's solution was studied. At the same time the changes of blood pressure, oxygen consumption, and influence on the blood pictures were observed before, during, and in 1-3 days after perfusion. Hemodilution rates were the average 74. 22cc/Kg(the ranges of 67 to 81 cc/Kg) and perfusion flow rates were maintained in the mean 62. 6cc/Kg/min., Although it was possible to check up to 87 cc/ Kg/min. The total body perfusion continued for 60-80 minutes. Hypothermia was employed between $36^{\circ}C$ and $32^{\circ}C$ of the rectal temperature. Arterial pressure was ranged approximately between 68mmHg and 149mmHg, but generally, it was maintained over 80mmHg. Venous pressure was measured between 6.5cm $H_2O$and 11.5cm $H_2O$. Optimum oxygenation can be expected when oxygen flow into the disposable bubble oxygenator was maintained approximately at 3.5 L/min .. Inthis way, the oxygen contents were measured in the mean value of 13.11${\pm}$O.56 vol. % of arterial blood and 8.67+1.08 vol.% of venous blood(P${\pm}$0.86 vol.% in arteriovenous oxygen difference and 2. 97${\pm}$0.62cc/Kg in oxygen consumption were calculated. According to these dates, it is as plain as pikestaff that excellent oxygenation and good tissue perfusion was accomplished. Erythrocyte, hemoglobin and hematocrit were decreased about 38% during extracorporeal circulation and these were not recovered until 1-3 days after perfusion. These decrease was resulted from relatively high degree of hemodilution rate and no blood transfusion to compensate during these experimental studies. The platelets were also decreased about 76% during perfusion, but on the contrary, it was increased progressively after perfusion and in 1-3 days after perfusion was returned to the control level. Leucocyte were also decreased during perfusion, but it was increased progessively after perfusion and in 1-3 days after perfusion exceed the control level. This increase was resulted from postoperative infection of the wound, but its analysis were not changed significantly.

• The Korean Journal of Nuclear Medicine
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• v.5 no.2
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• pp.7-18
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• 1971

The liver function test was performed by means of two radioisotope tracer techniques in 20 normal subjects and in 63 patients with hepatobiliary diseases. The blood disappearance rates of $^{131}I$-rose bengal and of $^{198}Au$ colloid were determined by external counting method. The hepatocellular function and the hepatic blood flow were estimated from the observed data and the results were compared with those of the conventional liver function tests. The results obtained were as follows: 1. The mean blood disappearance half time of $^{131}I$-rose bengal was $6.6{\pm}0.63$ minutes in normal control, $17.7{\pm}6.93$ in cirrhosis of the liver, $16.6{\pm}4.80$ in acute hepatitis, and $14.7{\pm}3.46$ in obstructive jaundice. It was markedly prolonged in the hepatobiliary diseases as compared with the normal control, but there was no significant difference among the hepatobiliary diseases. 2. The mean blood disappearance half time of $^{198}Au$ colloid was $4.0{\pm}0.66$ minutes in normal control, $9.8{\pm}3.42$ in cirrhosis of the liver, $4.4{\pm}0.82$ in acute hepatitis, and $5.0{\pm}1.42$ in obstructive jaundice. The difference between cirrhosis of the liver and normal control Was statistically significant. However, there was no definite difference among acute hepatitis, obstructive jaundice, and normal control. The mean blood disappearance rate constant (K value) was $0.177{\pm}0.028/minute$ in normal control. In cirrhosis of the liver, it was markedly decreased which was suggestive of the reduced hepatic blood flow. 3. The ratio of $^{131}I$-rose bengal blood disappearance half time to $^{198}Au$ colloid disappearance half time was $1.68{\pm}0.20$ in normal control, $1.82{\pm}0.31$ in cirrhosis of the liver, $3.80{\pm}0.82$ in acute hepatitis, and $3.01{\pm}0.54$ in obstructive jaundice. The ratios in acute hepatitis and obstructive jaundice were remarkably higher than those in normal control and cirrhosis of the liver. 4. There was a significant correlation between the blood disappearance half time of $^{131}I$-rose bengal and that of $^{198}Au$ colloid in cirrhosis of the liver. 5. In cirrhosis of the liver, the blood disappearance half times of $^{131}I$-rose bengal and of $^{198}Au$ colloid were inversely correlated to the serum albumin level. In acute hepatitis, there was a good positive correlation between the blood disappearance half time of $^{131}I$-rose bengal and the serum transaminase activities. In obstructive jaundice, the blood disappearance half time of $^{131}I$-rose bengal was correlated to the serum bilirubin level.