• Journal of Power System Engineering
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• v.11 no.2
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• pp.38-43
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• 2007

전자기적으로 지지되는 임펠러를 가진 원심 혈액 펌프는 기존의 심장 펌프에 비해 많은 장점을 가지고 있지만, BVAD의 틈새에서 발생하는 유체 동역학적인 문제는 여전히 규명이 되지 않은 상태이다. 본 연구에서는 BVAD의 틈새에서 발생하는 혈액외상(blood trauma)의 예측에 대한 연구에 중점을 두고 있다. 일반적으로 원심 혈액 펌프의 설계를 위해 전자기적으로 지지되는 원심 혈액 펌프의 디스크 틈새에서 발생하는 혈액의 손상을 평가하는 방법으로 CFD를 이용한 방법이 널리 이용되고 있다. 따라서, 본 연구에서는 초기 원심 혈액 펌프의 설계 단계에서 펌프의 특성을 평가하기 위하여, 축 방향 틈새의 영향과 회전수 변화에 따른 누수경로의 전단 응력의 크기 평가를 CFD를 사용하여 해석하여 보았다.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.139-150
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• 1989

A new motor-driven blood pump for artificial heart was developed. In this blood pump, a small size, high torque brushless DC motor was used as an energy converter and the motor rolls back and forth on a circular track. This movement of the "rolling-cyliner" causes blood ejection by alternately pushing left or right polyurethane blood sacs. This moving-actuator mechanism could be eliminate two potential problems of other motor-driven artificial hearts such as large size and poor anastomosis for the implantation. Theoretical analyses on the pump efficiency, the temperature rise, and the inflow mechanism were also performed. In a series of mock circulation tests, the theoretical analyses were compared to the measured hemodynamic and mechanical values. The pump system was shown to have sufficient cardiac output (upto 9 L/min), sensitivity to preload, and mechanical stability to be tested as an implantable total artificial heart.ial heart.

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.33-38
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• 1998

The intracardiac axial flow pump has been developed This device has several advantages: it fits well anatomically, its blood-contacting surface is small, and it is implanted as easily as an artificial heart valve replacement. The axial flow pump consists of an impeller and a motor, both of which are encased in a housing. Two types of impeller with 4 vanes and 6 vanes are used. Sealing of the motor shaft is achieved by means of a ferrofluidic seal. A flow of 5$\ell$/min was obtained at a differential pressure of 100mmHg with a motor speed of 7091rpm with the 4-vane impeller and 6402rpm with the 6-vane impeller. Sealing was kept against a pressure of 150mmHg at 7000rpm with the 4-vane impeller and 6402rpm with the 6-vane impeller. Sealing was kept against a pressure of 150mmHg at 7000rpm over 24 hours. The index of hemolysis was 0.056 with the 4-vane impeller and 0.214 with the 6-vane impeller. The intracardiac axial flow pump is a very promising circulatory support.

• 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.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.57-64
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• 2004

The non pulsation blood pump is divided into axial flow and centrifugal style according to the direction of inlet and outlet flow. An axial flow blood pump can be made smaller than a centrifugal blood pump because centrifugal pump's rpm is fewer than axial flow pump. Hemolysis is an important factor for the development of an axial flow blood pump. It is difficult to identify the areas where hemolysis occurs. Evaluation of hemolysis both in in-vitro and in-vivo test requires a long-time and more expensive. Computational fluid dynamics(CFD) analysis enables the engineer to predict hemolysis on a computer which just can get not only amount of htmolysis but also location of hemolysis. It takes shorter time and less expensive than in-vitro test. The purpose of this study is to git Computational fluid dynamics in axial flow pump and to verify the accuracy of prediction by the possibility of design comparing CFD results with in-vitro experimental results. Also, wish to figure out the correction method that can bring improvement in shape of axial flow blood pump using CFD analysis.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.4
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• pp.500-506
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• 2012

A method to model left ventricular assist device (LVAD) and detect suction occurrence for safe LVAD operation is presented. An axial flow blood pump as a LVAD has been used to assist patient with heart problems. While an axial flow blood pump, a kind of a non-pulsatile pump, has relative advantages of small size and efficiency compared to pulsatile devices, it has a difficulty in determining a safe pump operating condition. It can show different pump operating statuses such as a normal status and a suction status whether suction occurs in left ventricle or not. A fuzzy subtractive clustering method is used to determine a model of the axial flow blood pump with this pump operating characteristic and the developed pump model can provide blood flow estimates before and after suction occurrence in left ventricle. Also, a fuzzy subtractive clustering method is utilized to develop a suction detection model which can identify whether suction occurs in left ventricle or not.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.94-99
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• 2007

Many cases of acute cardiac shock and cardiac arrest in emergency room and ICU have been increasing. In this case, ECMO with centrifugal pump has been used generally. However, due to the heavy weight and big size, the system is not adequate for emergency cases. And other defects of this system are that membrane oxygenator's pressure is high and blood are exposed to the air. There was some tries of ECMO using pulsatile pump, but it was found that the weak point of these system is high peak pressure and hemolysis. The mechanism of twin pulsatile pump is that Membrane oxygenator Outlet Pump(MOP) make negative pressure when Membrane oxygenator Inlet Pump(MIP) provides high positive pressure, and the negative pressure will decrease positive pressure of Membrane Oxygenator. Our group analyzed this advantage through In-Vitro and 12 Cases In-Vivo test.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.153-158
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• 2006

최근 임상용 LVAD의 계속된 발전으로 인해 환자들의 삶이 연장되었다. 그러나 LVAD가 환자의 삶을 연장하였지만, 우심실 심부전증을 야기 시켰고, 결론적으로 환자들은 RVAD가 필요하게 되었다. 이러한 이유로 장시간 사용할 수 있는 BVAD의 도입이 요구 되어졌다. 최근 BVAD에 관련된 연구들을 보면 장시간 사용을 위한 원심 BVAD의 디자인과 BVAD에서의 누수 정도를 파악하는데 목적을 두고 있다. 따라서 본 논문에서는 BVAD의 누수를 파악하기 위한 속도 데이터와 용적당 흐름 비율의 계산을 CFD를 사용하여 해석적으로 조사하고자 하였다. CFD의 해석 결과 틈새부위의 회전수가 증가 할수록 혈액의 흐름을 방해하는 역류가 증가하고 유량도 줄어들어, 틈새부위의 누수량이 회전속도의 변화에 의존된다는 것을 확인 할 수 있었다.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.353-362
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• 2000

Minimization of hemolysis is one of the key factors for successful axial flow blood pumps. It is, however, difficult to estimate the hemolytic performance of axial flow blood pumps without experiments. Instead, the Computational Fluid Dynamics(CFD) analysis enables the prediction of hemolysis. Three-dimensional fluid dynamics of axial flow pumps with different impellers were analyzed using the CFD software, FLOTRAN. The turbulence model k-$\varepsilon$ was used. The changes in turbulent kinetic energy applied to each particle (red blood cell) flowing through the pumps were computed and displayed by the particle trace method (particle spacing of 10 msec). Also, the Reynolds shear stress was calculated from the turbulent kinetic energy. The shear stress was higher behind the impellers than elsewhere. The CFD analysis could predict in vitro results of hemolysis and also the areas where hemolysis occurred. The CFD analysis was found to be a useful tool for designing less hemolytic rotary blood pumps.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.141-145
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• 1992

심부전 환자의 심근회복을 도울 수 있는 장비인 전기유압방식 좌심실보조기를 개발하였다. 좌심실보조기는 혈액펌프, 압력펌프, 제어기로 구성되어 있으며, 혈액펌프에 내장된 혈액주머니는 동물실험을 위하여 50 ml의 크기로 제작하였다. 좌심실보조기의 성능평가를 위하여 최대 박출량을 측정하고 있으나 실험실에서 측정된 간은 동물 실험에서 관찰되는 것보다 일반적으로 증가된 박출량을 보이게 된다. 이는 생체에서는 좌심방의 체적이 박동 주기에 따라 변하여 좌심실보조기가 받아들일 수 있는 유효 혈액량이 변하는 반면, 모의순환장치에서는 좌심방을 단순 저장고로 사용하기 때문에 좌심방의 박동주기에 따른 체적변화를 감안하지 못하여 생기는 것이다. 본 실험에서는 모의순환 장치에 체적변화 가능한 100ml 크기의 좌심방을 연결하여 좌심방으로 들어오는 혈류량이 제한된 동물실험 상황을 모방하였다. 좌심실보조기의 제어방식중 수측기 이완기 비율(SD 비율)변화에 따른 좌심방 음압발생효과를 관찰한 결과 SD 비율을 40 %로 유지하면 행정거리가 클때도 좌심실의 음압발생을 줄일 수 있는 것을 관찰하였다.