• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.85-88
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• 1993

• 순환기질환의공학회:학술대회논문집
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• 2003.11a
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• pp.28-29
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• 2003

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.5-16
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• 2000

• Proceedings of the KTCVS Conference
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• 1993.06a
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• pp.122-122
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• 1993

• Journal of rehabilitation welfare engineering & assistive technology
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• v.1 no.1
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• pp.7-11
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• 2007

A compass device which indicates the right direction using the recorded voice was developed to assist the people who are blind when they are walking and moving to somewhere. The developed voice compass consists of a sensing module which recognizes the terrestrial magnetism with magnetic sensor, voice recorder IC, speaker and microprocessor which controlled all the components. It has 32 directions resolution and can continuously indicates the progressing direction with established time interval for the user convenience. It can help walking of the blind people and designed to be used in various sports and leisure. The performance of the developed device was verified by experiment with person who are blind.

• Journal of Yeungnam Medical Science
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• v.38 no.2
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• pp.95-106
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• 2021

Infections involving the heart are becoming increasingly common, and a timely diagnosis of utmost importance, despite its challenges. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a recently introduced diagnostic tool in cardiology. This review focuses on the current evidence for the use of FDG PET/CT in the diagnosis of infective endocarditis, cardiac implantable device infection, left ventricular assist device infection, and secondary complications. The author discusses considerations when using FDG PET/CT in routine clinical practice, patient preparation for reducing physiologic myocardial uptake, acquisition of images, and interpretation of PET/CT findings. This review also functions to highlight the need for a standardized acquisition protocol.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.8
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• pp.715-720
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• 2014

In order to maximize the effect of left ventricular assist device (LVAD) on ventricular unloading, the therapy should be begun at appropriate level of heart failure severity. We predicted pumping efficacy of LVAD according to the severity of heart failure theoretically. We used 3 dimensional finite element model of ventricle coupled with 6 Wind-kessel compartmental model of vascular system. Using the computational model, we predicted cardiac responses such as contractile ATP consumption of ventricle, left ventricular pressure, cardiac output, ejection fraction, and stroke work according to the severity of ventricular systolic dysfunction under the treatments of continuous LVAD. Contractile ATP consumption, which indicates the ventricular energetic loading condition decreased maximally at the $5^{th}$ level heart-failure under LVAD therapy. We conclude that optimal timing for LVAD treatment is $5^{th}$ level heart-failure when considering LVAD treatment as "bridge to recovery".

• International Journal of Fluid Machinery and Systems
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• v.7 no.1
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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.

• Journal of Chest Surgery
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• v.25 no.11
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• pp.1254-1260
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• 1992

Rupture of the posterior left ventricular wall following mitral valve replacement is a rare but fatal complication. Over a 10 year period from August 25 1980 to November 27 1990, we have experienced 6 such patients among 884 cases of mitral valve replacement with 4 deaths and 2 survivors. One patient had a type I rupture and another a type II rapture with the remaining four patients having suffered type III ruptures. All of the ruptures were dis covered intraoperatively enabling prompt reinstitution of the cardiopulmonary bypass and subsequent cardioplegic arrest prior to repair. Overzealous removal of calcified valve leaflets seemed to be responsible for the single type I rupture, and untethering of the so called ventricular loop appeared to be the main mechanism responsible for the type III ruptures. The single type II rupture that had occurred seemed to have been caused by inadvertent laceration of the papillary muscle with resultant rupture of the posterior LV wall at the base of the papillary muscle. Among the type III ruptures, 2 patients required intraaortic balloon pump[IABP] support only for mechanical assistance and 1 patient required both the IABP and the Biomedicus LV assist device for successfull weaning following repair of the LV rupture Another patient with a type II rupture also required the circulatory assistance of both the IABP and the bio-medicus LV assist device for weaning from the bypass. Attention to meticulous technical considerations such as avoiding over aggressive removal of heavily calcified valvular tissue, preservation of as much mural leaflet tissue and chordal stuctures as possible seemed helpful in preventing this catastrophic complication from occurring. Fusion and fibrous stricture of the chordal structures appeared particularly conducive to the type II ruptures as a result of the increased susceptibility to papillary injury during operation.

• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.225-234
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• 1992

In order to use a low cost polymer valve in our total artificial heart and ventricular assist device, we have developed a slit-type bileaflet polymer valve[BPV 1. The aim of this study is to determine the hydrodynamic effectiveness of the newly-designed BPV and its feasibility for temporary use in the blood pumps. For hydrodynamic comparison, we investigated in-vitro the pressure drop across the valve, the leakage volume, the flow rate and the flow pattern of the BPV, two mechanical valves and a trileaflet polymer valve. We employed the ventriculo-pulmonary bypassing method for in-vivo tests of the BPV's together vilh our electrohydraulic left venIn ricular assist device in mongrel dogs. The BPV showed adquate gydrodynamic performances and in the preliminary animal bests, there was no xvi dence of thrombus formation on the valve leaflets and around the struts. Detailed results obtained from the animal tests will be separately reported. This report involves the design criteria, fabrication and hydrodynamic charateristics of she BPV, and the basic merits and demerits of the valve are dis- cussed from the hydrodynamic point of view.