• Journal of Institute of Control, Robotics and Systems
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• v.1 no.2
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• pp.127-134
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• 1995

For use in patients with severe forms of heart disease for which no surgical repair is possible, development of artificial hearts has many importance in point of economics, medical and industrial applications. To provide a sufficient cardiac output to the physiological demands of circulatory systems is the objective of control systems for an electromechanical artificial heart, which is based on the stable controller design for the motor in the artificial heart. In this paper, an implantable microcontroller-based brushless DC motor control system with the implantability, reliability, and stability is introduced. The developed control system for the artificial heart has the following advantages: (1) It is possible to be implanted in a body by realizing the fundamental functions such as a motor speed detection, proportional-intergral control, timer, and PWM generation through a software programming. (2) Thus, the power consumed in the controller is reduced. (3) The reliability and stability are improved through the reduction of electronic parts and line connetions at the controller. The performance of the artificial hearts and control system developed was evaluated through a series of mock circulatory experiments and a reliability test for one and half years. A sheep with the artificial heart and control system was survived for three days.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.762-767
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• 1991

To make electromechanical total artificial heart implantable inside the body, transcutaneous energy transmission system was designed and simulated by using PSPICE program. The fabricated system was evaluated by using Mock circulation system and showed comparable performance with the D.C power supply

• Journal of Chest Surgery
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• v.22 no.2
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• pp.202-211
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• 1989

We experienced a series of animal experimental studies of the total artificial heart in 1988. So called, "Korean Heart* was used in this study, which is developed and fabricated in the Department of Biomedical Engineering, College of Med., S.N.U.. "Korean Heart" is a Rolling-Cylinder Motor-Driven type which is a newly developed electromechanical heart over the shortcomes of the previous artificial hearts, especially pneumatic type. The advantages of the "Korean Heart" are total implantability, quiet and smooth movement, small size fittable in oriental people, etc. The animal experiments were performed two times, as an assist device in sheep and total artificial heart implant experiment in calf weighing 100 kg. After total implantation, the artificial heart was well functioned in movement and hemodynamic control. So that, the calf was recovered excellently, which was able to stand up by herself and take an oral intake. Total survival time was 100 hours and the cause of death was a sudden pumping failure [electrical connection problem]. Several postoperative laboratory results almost within normal limits and no hemolysis, but in autopsy, the multiple thromboembolic findings were seen at the lung and kidney.n at the lung and kidney.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.858-863
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• 1988

A micro-processor based control system for a brushless DC motor used in the motor-driven electromechanical total artificial heart was developed. Functionally, the control system is composed of two parts. The first part is the velocity and position controller to assure that the motor follows a predetermined optimal velocity profile with minimal energy consumption, and to guarantee the full stroke length. This part also utilize the passive adaptive control method to be robust against the load disturbance, system parameter variation, and uncertainty which is the environment of artificial heart system. The pump output control is the second part, and this part provides the required responses of the artificial heart to the time-varying physiologic demands. The basic requirements of these responses are preload sensitivity, afterload insensitivity, and the balanced ventricular outputs. The performance and reliability of this control system was evaluated through a series of mock circulation tests and animal implantation, and the results are very encouraging.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.3
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• pp.38-47
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• 1995

A new automatic cardiac output control algorithm for the motor-driven electromechanical total artificial heart(TAH) was developed based on the motor current waveform analysis without using any extra transducer. The basic control requirements of artificial heart can be described in terms of three features : preload sensitivity, afterload insensitivity, and balanced ventricular outputs. In the previous studies, many transducers were utilized to obtain informations of hemodynamic states for the automatic cardiac output control, But such automatic control systems with sensors have had reliability problems. We proposed a new sensorless automatic cardiac output control algorithm providing adequate cardiac output to the time-varying physiological demand without causing right atrial collapse, which is one of the critical problem in an active-filling type device. In-vitro tests were performed on a mock circulation system to evaluate the performance of the developed algorithm and the results show that the new algorithm satisfied the basic control requirements on the cardiac output response and the possibility of application of the developed algorithm to in vivo experiments.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.161-170
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• 1987

A new type of motor-driven total artificial heart system with a rolloing-cylinder mechanism has been developed. The prototype system consists of a brushless DC motor inside of a rolling-cylinder, two arc shaped pusher-plate s, and two ventricles of smooth, seamless polyurethane sacs. The motor-driven pump has the advantages of being portable and quiet compared to the present air-driven pump. It can also be controlled more accurately. This rolling-cylinder type electromechanical pump has several structural advantages including small size and weight, as compared to other research groups' motor-driven pumps. The results of mock circulation tests confirm sufficient pump output capacity(cardiac output . 9 L/min, at aortic pressure'120mmHg, with heart rate . 120 BPM) for animal implantation of our prototype system.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.125-128
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• 1996

A new type of motor-driven total artificial heart system with a moving-actuator mechanism has been developed. The prototype system consists of a brushless do motor inside of actuator, two polyurethane sacs, and peripheral devices with internal controller. In this research work, the moving-actuator type electromechanical total artificial heart was redesigned for a good anatomical fitting. For total implantation we are developing the internal controller with high reliability and stability, and automatic control algorithm in response to the physiological requirements of animal. Contents and scope of the research work on ";Development of a totally implantable artificial heart of pre-clinical stage"; is summerized below 1) Animal experiment using sheep(55-60kg) 2) Development of implantable controller 3) Automatic control algorithm 4) Improvement of biocompatibility 5) Redesign of Actuator/blood pump.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.383-391
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• 1993

In this paper, a new automatic cardiac output control algorithm without any pressure sensors for the motor-driven electromechanical total artificial heart(TAH) was developed using motor current information. In the previous studies, many transducers were utilized to obtain informations of hemodynamic states for the automatic cardiac output control. But. such automatic control with sensors has some problems. To solve these problems, I proposed a new "sensorless" automatic cardiac output control algorithm providing the adequate cardiac output to the time-varying physiological demand without right atrial collapse. In-vitro tests were performed to evaluate the performance of a new algorithm and it satisfied the basic three requirements on the pump output response through the mock circulation tests.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.758-761
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• 1991

Using one chip microcontroller 87Cl96 (On chip EPROM type) and EPLD (Erasable & Programable Logic Device), an implantable control system to drive pendulum type electromechanical total artificial heart was developed. This control system consists of 4 parts, main management system, motor driver with power regulator, state monitoring system and communication part. The main system has the functions for speed detection, PI(proportional and integration) control, PWM generation, communication and analog data processor. Two kinds of power system were used and separated by 8 photo coupler arrays to improve the system stability. The performances of each compartments were compared with our previous z80 microprocessor based control system and good correspondences was shown. Logic power consumption was reduced to a one third of our previous controller. Using mock circulation tests, the overall performances of control system are evaluated.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.533-541
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• 1995

We recently developed a new model of moving actuator type totally implantable artificial heart[TIAH , based on the reverse position of the aortic and pulmonary conduits. This concept was proposed by one of surgeons in our team[Joon-Ryang Rho, M.D. to facilitate anatomical fitting of TIAHs. The moving actuator type electromechanical TIAH consisted of the left and right blood sacs, and the moving actuator including a motor. The inverted umbrella type polyurethane valves were used in the blood pumps. The aortic conduit was positioned anterior to the pulmonary conduit, which was the opposite relation to the conventional configuration of other total artificial hearts. We also adapted slip-in connectors for the aortic and pulmonary conduits. Two sheep , weighing 60-69 kg, were used for implantation. After small cervical incision and trans-sternal bilateral thoracotomy, cardiopulmonary bypass [CPB was administered using an American Optical 5-head pump and a membrane oxygenator[Univox-IC, Bentley . The anterior and posterior vena cavae were drained separately for venous return. An arterial return cannula was inserted into the right common carotid artery. During CPB, almost all of the ventricular myocardium was excised down to the atrioventricular groove and the artificial heart was implanted. We achieved 3-day survival in the first sheep and 2-day survival in the second. The day after operation the first sheep was successfully extubated and the second sheep was weaned from a respirator with good condition. After extubation, the first sheep walked around in the cage and fed herself. Serial laboratory and hemodynamic examinations were done during the experiments. In both sheep, pulmonary dysfunction was gradually developed, which was accompanied by acute renal failure. The animals were sacrificed and autopsy was done. Unexpected pregnnacy was incidentally found in both sheep. To our knowledge this is the first report of significant survival cases in the orthotopic implantation of electric TIAH using sheep.