• Journal of Institute of Control, Robotics and Systems
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• v.8 no.12
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• pp.1061-1065
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• 2002

Sensors need to be implanted to obtain necessary information for LVAS (Left Ventricular Assist System) operations. Size of the sensors can prevent them from being implanted in a patient and reliabilities of the sensors are questionable for a long term use. In this wort we utilize a developed pump model to estimate flow and pressure difference across the pump without implanted sensors and present a method to obtain the physiological variables as aorta pressure and left ventricle pressure from the pump model and pulsatility of flow estimate or pressure difference estimate. These estimated variables can be used for LVAS control as an index or indices.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.146-147
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• 1994

• Journal of Biomedical Engineering Research
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• v.3 no.1
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• pp.43-48
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• 1982

Ventricular assist device(VAD) has been clinically applied as a temporary circulatory sup- porting system in the patients with severe heart failure, but small sized VAD for infant is not available. The purpose of this paper is to introduce small sized VAD and presents the result of in vitro test. Sejong VAD is diaphragmatic type of pneumatic pump and stroke volume is 11cc. Cardiac outputs of the Sejong VAD were measured by overflow tank under variable conditions of driving parameters. The cardiac output was 1.3 1/min at the heart rate of 120 per minute, left atrial pressure of 15cmH2O, percent systole of 43%, driving pressure of 240 mmHg, vacuum pressure of -40 mmHg, and mean aortic pressure of 70 mmHg. No mechanical problem was developed during the continuous in vitro test for 3 months.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.11
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• pp.123-125
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• 1991

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.113-117
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• 1997

In this paper we detected the thrombosis formation by spectral analysis and neural network. Using microphone and amplifier, we measured the sound from the mechanical valve which is attached to the pneumatic ventricular assist device. The sound was sampled by A/D converter and the periodogram is the main algorithm or obtaining spectrum. We made the valvular thrombosis models using pellethane and silicon and they are thrombosis model on the disk, around the sewing ring and fibrous tissue growth across the orifice of valve. The spectrum of normal and 5 kinds of thrombotic valve were obtained and primary and secondary peak appeared in each spectrum waveform. So to distinguish the secondary peak of normal and thrombotic valve quantatively, 3 layer back propagation neural network.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.150-152
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• 1992

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.127-129
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• 1992

In this paper, we describe about control system for eletro-hydraulic LVAD(Left Ventricular Assist Device) and control algorithm for two operation mode. One is asynchronous operation mode and the other is synchronous operation mode synchronized with natural heart's R pulse. We also present implementation method of software PI algorithm for velocity control of motor used in LVAD system and its response.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.91-93
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• 1989

We have developed a monoleaflet polymer valve as an inexpensive and viable alternative, especially for short-term use in the ventricular assist device or total artificial heart. The frame and leaflet of the polymer valve were made from polyurethane, To evaluate the hemodynamic performance of the polymer valve a comparative study of flow dynamics past a polymer valve and a St. Jude Medical prosthetic valve under physiological pulsatile flow conditions in vitro was made. Comparisons between the valves were made on the transvalvular pressure drop, regurgitation volume and maximum valve opening area. The polymer valve showed smaller regurgitation volume and transvalvular pressure drop compared to the mechanical valve at higher heart rate. The results showed that the functional characteristics of the polymer valve compared favorably with those of the mechanical valve at higher heart rate.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.251-255
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• 1995

전기 유압식 좌심실 보조기에 있어서 현재 가장 큰 문제점 중의 하나로 지적되고 있는 것은 이완기에 좌심방의 혈액 유입상황을 고려하지 않은 과도한 밀판 당김 속도로 인해 생기는 좌심방의 함몰현상이다. 논문에서는 좌심방의 함몰현상을 구체적으로 정의하고, 좌심방의 함몰여부를 가늠하기 위해 외부에서 관측가능한 요소들과 좌심방의 상태와의 상관관계들을 고찰해 본 다음 이러한 함몰현상을 방지할 수 있도록 이완기 밀판 속도와 이동거리를 능동적으로 변화시키는 방식들을 구성하여 실험을 통해 그 효용성을 검증하였다.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.51-53
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• 1993

We have developed a monoleaflet polymer valve in order to be used as an inlet valve of the ventricular assist device, because it could help to improve the fluid dynamic characteristics in the ventricle. Mean systolic transvalvular pressure drops were measured for the monoleaflet polymer valve and their results were compared wi th that of the mechanical valve.