• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.2-7
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• 2002

Flow in the blood sac of the Korean artificial heart is numerically simulated by finite element method. Fluid-structure interaction algorithm is employed to compute the 3D blood flow interacting with the sac material. The motion of the actuator is simplified by a time-varying pressure boundary condition imposed on the outer surface of the sac. Numerical solutions show that there are a strong flow into the outlet and a stagnation flow near the inlet during systole. Shear stress distribution is also delineated to assess the possibility of thrombus formation.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.268-272
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• 1996

The removal of impulsive noise terms which occur in interventricular pressure (IVP) signals of a Korean-type total artificial heart is essential for estimation of atrial pressure change. We compared various order statistic filters and conclude that median filter with sidelength L = 1 is the most appropriate filter for IVP signals in the perspectives of operation cost, detail preserving (peak value), and waveform.

• 한국전산유체공학회:학술대회논문집
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• 2000.05a
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• pp.27-32
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• 2000

In this study, the three-dimensional blood flow within the sac of KTAH(Korean artificial heart) is simulated using fluid-structure interaction model. The numerical method employed in this study is the finite element commercial package ADINA. The thrombus formation is one of the most critical problems in KTAH. High fluid shear stress or stagnated flow are believed to be the main causes of these disastrous phenomenon. We solved the fluid-structure interaction between the 3D blood flow in the sac and the surrounding sac material. The sac material is assumed as linear elastic material and the blood as incompressible viscous fluid. Numerical solutions show that high shear stress region and stagnated flow are found near the upper part of the sac and near the comer of the outlet during diastole stage.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.695-696
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• 2002

Three-dimensional blood flow in the sac of the KTAH(Korean total artificial heart) is simulated using fluid-structure interaction model. The aim of this study is to delineate the three-dimensional unsteady-blood flow in the sac of KTAH. Incompressible viscous flow is assumed for blood using the assumption of Newtonian fluid. The numerical method employed in this study is the finite element software called ADINA. Fluid-structure interaction model between blood and sac is utilized to represent the deformation of the sac by the rigid moving actuator. Three-dimensional geometry of cactus type KTAH is chosen for numerical model with prescribed pressure boundary condition on the sac surface. Blood flow is generated by the motion of moving actuator and strongly interacts with the solid material surrounding blood. High shear stress is observed mainly near the inlet and outlet of the sac.

• Proceedings of the KTCVS Conference
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• 1993.06a
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• pp.124-124
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• 1993

• Korea-Australia Rheology Journal
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• v.16 no.3
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• pp.141-146
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• 2004

Shear-induced damage of Red Blood Cell (RBC) is an imminent problem to be solved for the practical application of artificial organs in extra corporeal circulation, as it often happens and affects physiological homeostasis of a patient. To design and operate artificial organs in a safe mode, many investigations have been set up to correlate shear and shear-induced cell damage. Most studies were focused on hemolysis i.e. the extreme case, however, it is important as well to obtain a clear understanding of pre-hemolytic mechanical damage. In this study, the change in deformability of RBC was measured by ektacytometry to investigate the damage of RBC caused by shear. To a small magnitude of pre-shear, there is little difference, but to a large magnitude of pre-shear, cell damage occurs and the effect of shear becomes significant depending on both the magnitude and imposed time of shearing. The threshold stress for cell damage was found to be approximately 30 Pa, which is much less than the threshold of mechanical hemolysis but is large enough to occur in vitro as in the extra corporeal circulation during open-heart surgery or artificial heart. In conclusion, it was found and suggested that the decrease of deformability can be used as an early indication of cell damage, in contrast to measuring plasma hemoglobin. As cell damage always occurs during flow in artificial organs, the results as well as the approach adopted here will be helpful in the design and operation of artificial organs.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.210-216
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• 2004

Flow visualization techniques were employed to qualitatively visualize the flow patterns through a 400％ scaled up centrifugal blood pump. The apparatus comprised of a scaled up centrifugal pump. high speed video camera. Argon Ion Laser Light Sheet and custom coded particle tracking software. Reynolds similarity laws are applied in order to reduce the rotational speed of the pump. The outlet (cutwater) region was identified as a site of high turbulence and thus a likely source of haemolysis. The region underneath the impeller was identified as a region of lower flow.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.101-106
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• 1998

This paper deals with the difference of the static and kinetic thrust characteristics of a linear pulse motor(LPM) without and with feedback control for a total artificial heart(TAH). In general, the kinetic thrust of LPM without feedback control decreases as increasing the mover velocity. The kinetic thrust characteristics of the LPM with feedback control are improved approximately 30% as compared with the LPM without feedback control in the high velocity range.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.122-125
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• 1997

It is needless to say that the hemodynamic variables estimation is a very important study or the artificial heart. Even though its importance there have not been satisfactory results which can be applied to the real-world situations. In this paper, we propose a practical afterload model ( AoP, PAP) which can be applied to the real-world situation.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.141-145
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• 1993

To Determine the major factor which causes the accelerated calcification of the severe flexing area of the artificial heart sac, comparative study under well defined in vitro situation were carried out. The results show that the effect of static mechanical stress is not so important. According to the data, change of surface area caused by the applied mechanical stress is one of the important factors of the heavy calcification of the severe flexing area of the artificial heart sac.