• 감성과학
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• 제26권3호
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• pp.149-160
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• 2023

본 연구에서는 뇌혈류 신호를 측정할 수 있는 시변자계 기반의 비접촉식 직물센서를 설계하여 뇌혈류 신호 검출 및 감성평가의 가능성을 탐색하고자 하였다. 직물센서는 40 denier의 은사를 30합사 한 후 컴퓨터 기계 자수하여 코일형 센서로 구현하였다. 뇌혈류 측정 실험을 위해 코일형 센서를 경동맥 부위에 부착하고, ECG (Electrocardiogram) 전극과 RSP (Respiration) 측정 벨트를 부착 및 착용하도록 하였으며, 동시에 초음파 진단기기를 사용해 도플러 초음파 검사(Doppler Ultrasonography)를 수행하여 혈류 속도를 측정하였다. 피험자에게 Meta Quest 2를 착용시키고, 실험을 위해 조작된 영상 시각 자극을 보여주면서 혈류 신호를 측정한 후 시각 자극에 대한 감성평가 설문지를 작성하도록 하였다. 측정 결과, 도플러 초음파 검사를 통해 측정된 혈류 속도 신호에 변화가 생길 때 직물센서로 측정한 신호도 함께 변화하는 것으로 나타났다. 이를 통해 코일형 직물센서를 이용하여 뇌혈류활동 신호를 측정할 수 있다는 것을 검증하였다. 또한, 감성평가를 위하여 ECG 신호와 PLL 신호(직물센서 신호)에서 추출한 HRV를 계산해서 비교한 결과, 시각 자극으로 인한 교감신경계와 부교감신경계의 활성화에 따른 비율의 변화에 대해서는 직물센서로 측정한 신호와 ECG 신호를 이용해 계산한 값이 비슷한 경향을 보이는 것으로 나타났다. 결론적으로, 본 연구에서 개발된 시변자계 기반의 코일형 직물 센서를 통해 뇌혈류 변화 측정 및 감성 모니터링이 가능할 것으로 사료된다.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1313-1320
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• 2005

Stenosed coronary artery may play an important role in various coronary heart diseases. However, it has not been known how much stenosed coronary artery affects coronary circulation system, quantitatively. The present study developed a mathematical model for microcirculation in the left common coronary artery (LCCA) with adopting a previously measured morphological data and mechanical properties of the coronary vessels. We examine the effect of percent diameter stenosis on blood flow rate and shear stress for two cases. Case I comprised of one-stenosed element at $10^{th}$ order ($\%$ diameter stenosis are 10, 30, and 50, respectively). Case II consisted of completely occluded element at $10^{th}$ order (number of occluded elements are 0, 1, and 2 out of 8, respectively). As the level of stenosis becomes severe, the shear stress increases significantly but the flow rate reduction was relatively small. However, for the occluded case, there was linearly proportional reduction of flow rate according to number of occluded elements. Either such high shear stress associated with coronary artery stenosis or reduced flow rate due to occlusion may cause atherosclerosis and myocardial ischemia.

• Journal of Chest Surgery
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• 제37권4호
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• pp.342-348
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• 2004

말기 신부전 환자의 생명 유지를 위한 혈액투석 치료에 있어서 지속적으로 개존상태가 유지되고 충분한 혈액이 관류되는 투석 경로의 확보는 매우 중요하다. 동정맥루 조성술 시행 후 조기 폐쇄로 인해 투석을 시행하지 못하는 경우, 환자는 경정맥 또는 대퇴정맥 등의 중심 정맥 삽관을 반복적으로 시행 받아 혈액투석을 유지해야 하며 경제적, 시간적 손실을 감수해야 하는 어려움을 겪게 된다. 대상 및 방법: 자가 혈관을 이용한 동정맥루 조성술에 있어 조기개존율에 영향을 미치는 요인을 파악하고, 이를 향상시키기 위해서 2002년 6월부터 2003년 5월까지 1년 간 말기 신부전 환자에게 시행한 총 85예의 동정맥루 수술 중 두부정맥(cephalic vein)과 요골동맥(radial artery)의 단측문합(end-to-side anastomisis)을 시행한 49예를 대상으로 임상분석을 하였다. 걸과: 연구대상 49예에서 조기개존율은 79.6%였다. 환자의 나이나 성별, 고혈압과 당뇨병 유무에 따른 개존율의 차이는 없었으며 환자의 체질량지수 및 고혈압과 당뇨의 유병기간, 술 전 듀플렉스 검사로 측정한 요골동맥의 직경에 따른 조기개존율의 차이는 통계적으로 유의하지 않았다. 수술 전 듀플렉스 검사로 측정한 두부정맥의 직경과 수술 시 측정한 동정맥루의 혈류량이 조기개존율과 유의한 양의 상관관계를 나타내었고, 특히 혈관직경 2.7mm가 초과되는 군에서는 조기 폐쇄 없이 개존율이 100%로 유지되었으며 동정맥루의 혈류량이 100mL/min 이하인 군에서는 조기개존율 33.3%로 100 mL/min초과인 군의 82.2%와 비교할때 유의하게 조기개존율이 낮았다. 결론: 동정맥루에 사용되는 정맥의 직경은 개존율과 밀접한 관련이 있어 가능한 한 직경이 큰 정맥을 선택해야 하며 연구에 따라 다양한 기준이 보고되어 왔으나 보다 정확한 예후 판단을 위해서는 정맥의 직경뿐 아니라 혈관 유출로의 혈류와 협착상태 등에 대한 파악이 필요할 것으로 생각된다. 본 연구에서 측정한 수술 시 동정맥루의 혈류량을 기준으로 판단할때, 100 mL/min 이하의 혈류량을 나타내는 radiocephalic fistula에서는 혈류량 감소의 원인을 찾아 교정술을 시행하고 그 이후에도 혈류량이 증가하지 않을 경우 다른 부위의 혈관 또는 인조혈관의 사용을 고려하여야만 할 것이다.

• International Journal of Vascular Biomedical Engineering
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• 제1권1호
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• pp.24-31
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• 2003

As endothelial cells are subject to flow shear stress, it is important to determine the detailed velocity distribution in microvessels in the study of mechanical interactions between blood and endothelium. This paper describes a velocity field of the arteriole in the rat mesentery using an intravital microscope and high-speed digital video system obtained by a highly accurate PIV technique. Red blood cells (RBCs) velocity distributions with spatial resolutions of $0.8{\times}0.8{\mu}m$ were obtained even near the wall in the center plane of the arteriole. By making ensemble-averaged time-series of velocity distributions, velocity profiles over different cross-sections were calculated for comparison. The shear rate at the vascular wall also evaluated on the basis of the ensemble-averaged profiles. It was shown that the velocity profiles were blunt in the center region of the vessel cross-section while they were steep in the near wall region. The wall shear rates were significantly small, compared with those estimated from the Poiseuille profiles.

• Journal of Chest Surgery
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• 제3권2호
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• pp.73-90
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• 1970

Clinical perfusion data on 16 cases of cardiopulmonary bypass using Sigmamotor pump and RyggKyvsgaard Oxygenator which performed at Seoul National University Hospital during the period of Aug. 1968 to Aug. 1970 was analized. AIl cases were hemodiluted and the perfusion was carried out under the normothermic condition. The age of the patients ranged between 6 and 43 years. The b:dy weight varied between 18.3 and 54.0 kg and the body surface area between 0.78 and 1. 59$M^2$. The priming solution was consiste:I with fresh ACD blood. Hartmann solution and Mannitol. The average amount of priming was approximately 2242 ml. The average hemodilution rate was 17%. The flow rate ranged from 1.7L to 3.5L/Min/$M^2$ and averaged 2.4L/Min/$M^2$ or 78mI/Min/kg. The duration of perfusion varied from 22 to 110 min with average of 56.9 minutes. Some hemodynamic responses were observed. The arterial pressure dropped immediately after the initiation of partial perfusion and was more marked after the total perfusion foIlowed by gradual increase to the safety level. The central venous pressure reflected the reduced blood volume especially in the cases of prolonged perfusion which lasted over 60 min. In most of the cases, red blood cell count decreased and white blood ceIl count increased after the perfusion. Hemoglobin level was decreased, averaging of 12.5mg%, Hct 3.3% and platelets count of 18% postoperatively. Plasma hemoglobin increased mildly, from pre-perfusion average value of 4. 06mg% to postperfusion value of 22.5mg%. Serum potassium was 4.4mEq/L pre-operatively and was decreased to 3.7mEq/L postoperatively. Five cases showed definite hypopotassemia immediately after the operation. Sodium and chloride decreased mildly. These electrolyte changes are thought to be related with hemodilution. diuretics and reduced blood volume during and after the perfusion. Arterial blood pH value revealed minimal to moderate elevation from preperfusion average value of 7.376 to 7.461 during perfusion and then 7.365 after perfusion. The pC02 and hicarbonate showed minimal to moderately lowered values. The total CO2 was decreased. Buffer base decreased during perfusion (Av. 42.6mEq/L) and further decreased after the perfusion (Av. 40.8mEq/L). These arterial blood acid base changes suggested that the metabolic acidosis was accompanied by respiratory alkalosis during and immediately after the perfusion. Authors belived that the acidosis could more effectively be corrected with the more additional dose of bicarbonate than we used by this study. The chest tune drainage during the first 24 hours following operation was 1158 ml in average. One case (Case No. 15) showd definite bleeding tendency and it was believed that the cause might be due to the defect of heparin and protamine titration. The average urinary out put during 24 hours post-perfusion was 1291ml. One case (Case No. ]) showed definite post perfusion oliguria. As conclusion hemodilution using fresh ACD blood. Hartmann and Mannitol solution added with Bivon and high flow rate unler normothermia. was thought to amelioratc the severity of mctabolic acidosis during and after perfusion with relatively satisfactory effect on the diuresis and bleeding tendency.

• 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.

• Biomolecules & Therapeutics
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• 제7권2호
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• pp.170-177
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• 1999

PEG-hemoglobin SB1 (SB1), which is a hemoglobin-based oxygen carrier, is intended to use as a safe blood substitute against brain ischemia and stroke. The general pharmacological profiles of SB1 were studied. The doses given were 0, 5, 10, 20 ml/kg and drugs were administered intravenously. The animals used for this study were mouse, rat and guinea pig. SB1 showed no effects on general behavior, motor coordination, spontaneous locomotor activity, hexobarbital sleeping time, anticonvulsant activity, analgesic activity, blood pressure and heart rate, left ventricular peak systolic pressure, left ventricular end diastolic pressure, left ventricular developing pressure, double product, heart rate, coronary flow rate, smooth muscle contraction using guinea pig ileum, gastrointestinal transport, gastric secretion, urinary volume and electrolyte excretion at all doses tested except the decrease of body temperature. These findings demonstrated that SB1 possesses no general pharmacological effects at all doses tested.

• 한국정보전자통신기술학회논문지
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• 제2권3호
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• pp.71-78
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• 2009

본 논문에서는 측정된 PPG 신호로부터 심박동수를 추정 하는 방법을 제시한다. PPG 신호는 현관에 흐르는 혈류량을 측정한 것으로 심장의 수축과 이완에 영향을 받아 단일 주파수적인 특성을 가지며 이러한 특성을 이용하여 PPG 주파수를 2차 IIR 적응 놋치 필터로 추적한다. 적응 알고리즘을 통하여 지속적으로 필터 계수를 갱신하여 얻어진 PPG 주파수를 바탕으로 사람의 심박동수를추정한다.

• The Korean Journal of Physiology
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• 제3권1호
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• pp.59-66
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• 1969

Experiments on thermoregulatory responses to cold immersion stimulus were carried out in September, 1968 (summer studies) and February, 1969 (winter studies). Eight each of ama and control subject were selected at random from a same community in Yong-Do Island, Pusan. The results obtained are summarized as follows: 1) The rate of fall in muscle temperature of forearm during a 30 min-immersion in $6^{\circ}C$ water bath was significantly slower in the ama in winter and was about the same in the two groups in summer. However, the magnitude of change in the skin temperature and the heat fluxes observed during immersion period was not significantly different either between groups or between seasons. 2) Both finger blood flow and skin temperature during one hr-immersion in $6^{\circ}C$ water bath decreased significantly in the ama as compared to the control. The magnitude of cold-induced vasodilatation during immersion period was significantly greater in the control in winter. However, the time of onset and blood flow at onset showed no significant relation between groups. 3) The magnitude of reactive hyperemia after a 5 min-arterial occlusion in both air and $15^{\circ}C$ water bath was significantly lower in the ana than in the control. In control subjects, post-occluded blood flow in water was significantly greater than in air, while in the ama it decreased to 1/2 of control values. The time required for the return of blood flow to resting values in the air was faster in the ama than in the control but was the same in water in the two groups. 4) The results suggest that vasoconstrictor tone increased in the ama in winter, indicating the development of vascular adaptation as a part of cold acclimatization.

• International Journal of Fluid Machinery and Systems
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• 제7권1호
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• pp.34-41
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• 2014

Computational fluid dynamics (CFD) and particle image velocimetry (PIV) are commonly used techniques to evaluate the flow characteristics in the development stage of blood pumps. CFD technique allows rapid change to pump parameters to optimize the pump performance without having to construct a costly prototype model. These techniques are used in the construction of a bi-ventricular assist device (BVAD) which combines the functions of LVAD and RVAD in a compact unit. The BVAD construction consists of two separate chambers with similar impellers, volutes, inlet and output sections. To achieve the required flow characteristics of an average flow rate of 5 l/min and different pressure heads (left - 100mmHg and right - 20mmHg), the impellers were set at different rotating speeds. From the CFD results, a six-blade impeller design was adopted for the development of the BVAD. It was also observed that the fluid can flow smoothly through the pump with minimum shear stress and area of stagnation which are related to haemolysis and thrombosis. Based on the compatible Reynolds number the flow through the model was calculated for the left and the right pumps. As it was not possible to have both the left and right chambers in the experimental model, the left and right pumps were tested separately.