• 순환기질환의공학회:학술대회논문집
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• 2006.10a
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• pp.55-56
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• 2006

• 순환기질환의공학회:학술대회논문집
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• 2004.11a
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• pp.38-39
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• 2004

• 순환기질환의공학회:학술대회논문집
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• 2004.11a
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• pp.52-53
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• 2004

• 순환기질환의공학회:학술대회논문집
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• 2004.05a
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• pp.71-76
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• 2004

• 순환기질환의공학회:학술대회논문집
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• 2003.11a
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• pp.42-43
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• 2003

• 순환기질환의공학회:학술대회논문집
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• 2002.11a
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• pp.3-18
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• 2002

Hemorheology plays an important role in atherosclerosis. Hemorheologic properties of blood include whole blood viscosity, plasma viscosity, hemaocrit, RBC deformability and aggregation, and fibrinogen concentration in plasma. Blood flow is determine by three parameters (pressure, lumen diameter, and whole blood viscosity), whole blood viscosity is one of the key physiological variables. However, the significance of whole blood viscosity has not yet not been fully appreciated. Whole blood viscosity has a unique property, non-Newtonian shear-thinning characteristics, which is primarily due to the presence of RBCs. Hence, RBC deformability and aggregation directly affect the magnitude of blood viscosity, and any factors or diseases affecting RBC characteristics influence blood viscosity. Therefore, on can see that whole blood viscosity is the causal mechanism by which traditional risk factors such as hypertension, hyperlipidemia, smoking, exercise, obesity, age, and gender are related to atherogenesis. In this regard, we included whole blood viscosity in the three key determinants of injurious pulsatile flow that results in mechanical injury and protective adaptation in the arterial system. Because whole blood viscosity is a potential predictor of cardiovascular diseases, it should be measured in routine cardiovascular profiles. Incorporating whole blood viscosity measurements into a standard clinical protocol could improve our ability to identify patients at risk for cardiovascular disease and its complications.

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.768-776
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• 2007

A new type of the fluid circulation blood pressure simulator was proposed to enhance the blood pressure simulator used for the development and evaluation of automatic sphygmomanometers. Various pressure waveform of fluid flowing in the pipe was reproduced by operating the proportional control valve after applying a pressure on the fluid in pressurized oil tank. After that, appropriate fluid was supplied by operating the proportional control valve, which enabled to reproduce various pressure wave of the fluid flowing in the tube. To accomplish this work, the mathematical model was carefully reviewed in cooperating with the proposed simulator. After modeling the driving signal as input signal and the pressure in internal tube as output signal, the simulation on system parameters such as internal volume, cross-section of orifice and supply pressure, which are sensitive to dynamic characteristic of system, was accomplished. System parameters affecting the dynamic characteristic were analyzed in the frequency bandwidth and also reflected to the design of the plant. The performance evaluator of fluid dynamic characteristic using proportional control signal was fabricated on the basis of obtained simulation result. An experimental apparatus was set-up and measurements on the dynamic characteristic, nonlinearity, and rising and falling response was carried out to verify the characteristic of the fluid dynamic model. Controller was designed and thereafter, simulation was performed to control the output signal with respect to the reference input in the fluid dynamic model using the proposed proportional control valve. Hybrid controller combined with an proportional controller and feed-forward controller was fabricated after applying a disturbance observer to the control plant. Comparison of the simulations between the conventional proportional controller and the proposed hybrid simulator indicated that even though the former showed good control performance.

• The Journal of Korean Medicine
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• v.20 no.4
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• pp.11-15
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• 2000

Radix Angelicae Gigantis is sweet and pungent in flavor, warm in property. Its effects are tonifying the blood, promoting blood circulation, relieving pain and moistening the bowels. Its indications are blood deficiency syndrome characterized by sallow complexion, dizziness, irregular menstruation, amenorrhea, pains due to blood stasis, and rheumatic arthralgia. Using genes of A. gigas, A. acutiloba, and A. sinensis, the origin of which is identified, as criteria, we analysed many kinds of Angelica with RAPD and RFLP on ITS region, in order to compare and discriminate genes extracted from crude drugs ‘Dang-gui’, that are produced in Korea on the one hand and imported on the other hand. We reached the following conclusion. 1. We could extract DNA from both original plant and dried plant. 2. Especially Uniprimer #1, Uniprimer #2, Uniprimer #4 and Uniprimer ＃9 were useful. 3. Among the restriction enzymes Sma I, Msp I, Hae III, and Hinf I, used in this experiment, four restriction enzymes except Hinf I could be used properly in discriminating all samples used as A. gigas. We think that this result can be used as a method of discriminating crude drug of Angelica L. related drugs, and used in controlling quality and circulation.

• Journal of Chest Surgery
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• v.22 no.4
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• pp.525-547
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• 1989

Hemorrhagic tendency observed in open heart surgery patients has been attributed, among other causes, to increased fibrinolytic activity during extracorporeal circulation. But the exact mechanism of enhanced fibrinolytic activity which occurs during extracorporeal circulation is still unknown. So, we studied and compared the changes of parameters of fibrinolytic and protein C system according to time obtained from the plasma of 31 adult open heart surgery patients[EGG group] and 10 adult general thoracic surgery patients[control group], in order to confirm the hypothesis that the activated protein C system might affect the fibrinolytic system during extracorporeal circulation. In ECC group, the nature of the enhanced fibrinolytic activity that evolved during extracorporeal circulation was characterized by significant increase in fibrin degradation products[P < 0.01] and significant decrease in plasminogen and alpha2-antiplasmin[P < 0.05, P < 0.01] in spite of adequate amount of heparin administration. These changes were most pronounced in the early phase of extracorporeal circulation and normalized after termination of extracorporeal circulation. The results of these observations were the same after volume correction with the value of hematocrit. The change of volume corrected protein C ratio during extracorporeal circulation revealed similar pattern to those of plasminogen and alpha2-antiplasmin [P < 0.01], but volume corrected ratio of free protein S showed significant increase after the commencement of extracorporeal circulation then decreased after extracorporeal circulation. Although the above mentioned changes occur similarly in both bubble type oxygenator-used and membrane oxygenator-used patients groups, but the degree of decrease was more severe in membrane oxygenator-used patients group [P < 0.01] and showed much slower recovery to reach to the preextracorporeal circulation level. These results confirm the hypothesis that the enhanced fibrinolysis during extracorporeal circulation might be caused by the activation of protein C system and the activation is possibly linked to the appearance of thrombin from contact activation of blood after wide exposure to the synthetic surfaces of extracorporeal circuit. Key words: Extracorporeal circulation, Enhanced fibrinolysis, Protein C system.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.51-60
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• 2000

This paper outlines the development of a non-pulsatile axial flow type blood pump control system. By utilizing blood pressure and heart rate, this system can assist the left ventricle in controlling blood pressure and blood volume. The system is comprised of a blood pump, signal sensor, signal interface, and signal-processing component. A control algorithm is also proposed which can control non-pulsatile, continuous blood flow in the human circulatory system. To facilitate the control required for non-pulsatile blood pump in a physiological system, an experimental control rule was developed utilizing ECG and blood pressure data, both of which are easily detectable variables in the body. The system was then tested using a mock-up circulation system and we found that it is possible that this systems could be temporarily used in clinic.