• 대한기계학회논문집B
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• 제29권4호
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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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• 제54권1호
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• pp.535-544
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• 2015

이 연구는 노인 여성에 대한 저항성 훈련 시 혈류제한(blood flow restriction)을 적용할 경우 저강도 운동을 통해서도 하지의 근력과 근육량을 효과적으로 향상시킬 수 있는지를 검증하기 위해 수행되었다. 총 16명의 노인 여성(연령 70.9±4.6)을 저강도 운동 집단(30% 1 RM, n=8)과 고강도 운동 집단(75% 1 RM, n=8)으로 구분하였다. 두 그룹 모두 우측 하지는 대퇴 근위부에 혈류제한용 커프(cuff)를 착용한 상태에서, 좌측 하지는 혈류제한 장치 없이 동일한 운동을 수행한 후 트레이닝 전·후의 근육량과 근력 변화를 분석하였다. 저항성 운동 프로그램은 leg press, leg extension, leg curl을 12회 반복으로 3세트씩 총 10주간 주 2회 실시하였다. 자기공명영상분석기(MRI)로 근 횡단면적(CSA)과 근육량을 산출하였으며, 체성분 변화는 이중에너지 방사흡수 계측기(DEXA), 근력 평가는 등속성 운동 장비(HUMAC Norm)를 이용하였다. 연구를 통해 10주간의 저항성 훈련 후 혈류제한을 적용한 상태에서 고강도 운동을 수행한 집단의 대퇴사두근 근횡단면적(15.2%, p<.001)과 근육량(13.8%, p<.001)이 증가하였으며 이러한 긍정적 변화는 혈류제한 상태에서 저강도로 운동한 집단의 횡단면적(9.8%, p<.001)과 근육량(6.9%, p<.001) 변화에서도 확인할 수 있었다. 한편, 근력은 운동 수행만으로도 향상되었으나 혈류를 제한할 경우 향상도가 더 높은 경향을 보였다. 따라서 이 연구는 혈류제한을 적용할 경우 저항성 운동을 저강도로 수행하더라도 노인 여성의 근 비대와 근력 증가에 효과적으로 작용할 가능성을 시사한다.

• 대한기계학회논문집A
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• 제29권12권
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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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• 제40권1호
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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.

• 한국의류학회지
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• 제17권3호
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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.

• 한국의학물리학회지:의학물리
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• 제14권2호
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• pp.141-148
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• 2003

정상적인 어린이와 ADHD 질환군 어린이와의 뇌혈류 상태를 비교하기 위하여 SPECT 영상을 획득하고, 정량적 분석 방법으로 유의수준별 혈류의 증가 또는 감소가 나타나는 클러스터(cluster)의 분포변화와 증가 또는 감소율의 변화를 조사하고자 한다. 64명의 어린이 ADHD환자군과 12명의 정상군에 대하여, Multi SPECT 3 (Simens) camera를 이용하여 방사성의약품 $^{99m}Tc-ECD$를 정맥 주사후 30분에 영상을 획득하고, 뇌혈류 상태를 통계적 파라미터 지도작성법(SPM99)으로 분석하였다 정상 어린이군에 대한 ADHD환자군의 뇌혈류 증가와 감소부위의 분포와 비교하기 위하여 통계적 유의수준 P<0.001부터 P<0.05범위에서 나타내었다. ADHD환자군의 뇌혈류 증가부위로 유의수준 P<0.003에서 P<0.01까지 대상회전에서 나타나기 시작하였으며, p<0.03에서 우측의 대뇌후엽, p<0.05에서는 소뇌 좌측상부 등 3개의 클러스터가 나타났다. 대상회전에서, 정상군에 비하여 ADHD 질환군이 평균 19.83%의 혈류증가율을 나타내었으며, 32명의 ADHD 환자는 19.83%이상 증가되었다. 대뇌 우측후엽에서는 정상군보다 평균 19.61%가 증가되었고, 환자 수는 36명이었다. 그리고 소뇌의 좌측상부에서는 평균18.72%의 증가율을 나타냈으며, 평균 증가율보다 더 많은 증가율을 나타내고 있는 ADHD 환자는 34명이었다. 각각의 클러스터에서 혈류 증가율과 환자 수는 유의수준의 변화에 영향을 받지 않았다. 뇌혈류감소의 경우, 유의수준 P<0.002에서 좌측의 대뇌전엽에서 감소를 나타내는 클러스터가 나타나기 시작하여, 유의수준 P<0.01까지 좌, 우의 대뇌전엽, 좌측의 대뇌 전장(claustrum). 우측의 대뇌측엽 등에서 감소된 클러스터가 뚜렷하게 나타났다. 좌측의 대뇌전엽에서 정상군에 비하여 18.79%가 감소되었고, ADHD환자중 36명은 18.7%이상 감소되었다. 좌측의 대뇌 전장에서는 18.41%가 감소되었고, 33명의 ADHD환자는 18.41%이상 감소되었다. 혈류의 감소율과 환자수는 유의수준 값의 변화에 영향을 받지 않았다.

• 한국의류학회지
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• 제44권2호
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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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• 제66권4호
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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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• 제4권2호
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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.

• 대한핵의학회지
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• 제5권2호
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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.