• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.83-90
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• 1998

In this paper, we present neural network for control of Left Ventricular Assist Device(LVAD) system with a pneumatically driven mock circulation system. Beat rate(BR), Systole-Diastole Rate(SDR) and flow rate are collected as the main variables of the LVAD system. System modeling is completed using the neural network with input variables(BR, SBR, their derivatives, actual flow) and output variable(actual flow). It is necessary to apply high perfomance control techniques, since the LVAD system represent nonlinear and time-varing characteristics. Fortunately. the neural network can be applied to control of a nonlinear dynamic system by learning capability In this study, we identify the LVAD system with neural network and control the LVAD system by PID controller and neural network feedforward controller. The ability and effectiveness of controlling the LVAD system using the proposed algorithm will be demonstrated by experiment.

• The KSFM Journal of Fluid Machinery
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• v.16 no.5
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• pp.24-28
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• 2013

Visualization of internal flow of a regenerative blower has been made by injecting a tracer directly into the flow. For the convenience of visualization, working fluid has been replaced by water and marbling color oil has been used as a tracer. Oil droplet has been injected near the inlet of the blower and the streak has been recorded using a high speed camera with the illumination of high power light sources. At first, droplets have irregular motion in the near inlet area and enter into a groove of the impeller. Then the droplets circulate inside the groove while translated by the rotational motion of the impeller. When the droplets get out of the impeller groove, their speed is lower than that of impeller. And the droplets repeatedly enter into the groove and circulate inside the grooves. Then the droplets either flow to the outlet or reenter into the inlet area through stripper. Through this experimental study, internally circulating motion of the flow inside a regenerative blower has been characterized.

• Korean Journal of Veterinary Research
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• v.37 no.3
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• pp.661-668
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• 1997

Portal blood flow was measured with pulsed doppler ultrasound in thirty normal dogs. In normal dogs, the average portal blood flow velocity was $17.03{\pm}1.75cm/sec$ and the average portal blood flow was $41.59{\pm}10.10ml/min/kg$. The incident angle between the doppler beam and the portal vein averaged $65^{\circ}$. The average portal vein sectional area was $0.41{\pm}0.14cm^2$. The Congestion index was $0.0245{\pm}0.0081cm{\cdot}sec$. Conclusively, the spectral doppler ultrasonography was quick, non-invasive and simple diagnostic method in circulatory disorders of liver.

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.47-52
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• 1998

To develop the supplementary heart valve which could reduce the complications of prosthetic heart valve, in vitro experiments were performed to analyze the movement of the supplement valves from the view point of the flow dynamics and leaflet dynamics. The autologous pericardium was attached to deficient portion of the porcine valve which was dissected completely and partially. The pericardium was treated by buffered glutaraldehyde solution in the preshaped mould to preserve the shape of the leaflet. The function of the valves were evaluated in the mock circulatory system and three sets of experiment were performed. The instantaneous motion of the leaflet was pictured by the 35mm camera and the pressure drop through the valve and cardiac output were measured. The supplementary valve which was replaced completely performed better thatn the valve replaced partially. In vitro experiments showed that the supplementary valve which was replaced completely performed better than the valve replaced partially. In vitro experiments showed that the supplementary valve could undertake the prosthetic heart valve in clinic.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.87-94
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• 2006

This paper presents the hydrodynamic design and performance analysis method for a miniaturized centrifugal blood pump using three-dimensional computational fluid dynamics (CFD) code. In order to obtain the hydraulically high efficient configuration of a miniaturized centrifugal blood pump for cardiopulmonary circulation, a well-established commercial CFD code was incorporated considering detailed flow dynamic phenomena in the blood pump system. A prototype of centrifugal blood pump developed by the present design and analysis method has been tested in the mock circulatory system. Predicted results by the CFD code agree very well with in vitro hydraulic performance data for a centrifugal blood pump over the entire operating conditions. Preliminary in vivo animal testing has also been conducted to demonstrate the hemodynamic feasibility for use of centrifugal blood pump as a mechanical circulatory support. A miniaturized centrifugal blood pump developed by the hydraulic design optimization and performance prediction method presented herein shows the possibility of a good candidate for intra and extracorporeal cardiopulmonary circulation pump in the near future.

• Journal of Biomedical Engineering Research
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• v.22 no.4
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• pp.349-358
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• 2001

A novel electro-mechanical implantable ventricular assist system is developed as a bridge to transplantation or recovery for patients with end-stage heart failure. The developed system is composed of an implanted blood pump, an external monitoring system which stores data, and a wearable system including a portable external driver and a portable power supply system. The blood pump is designed to be implanted into the left upper abdominal space and provides blood flow from the left ventricular apex to the aorta. The pulsatile blood flow is generated by a double cylindrical cam. There was mo excessive heat emission from the blood pump into the temperature-controlled chamber in the heat test and no stagnated flow within the blood sac by the observation in the flow visualization test. Animal experiments were performed using sheep and calves. The maximum assist flow rate reached 7.85L/min in the animal experiment. The evaluation results showed that the developed system was feasible for the implantable ventricular assist system. The long-term in vitro durability test and mid-term in vivo experiments are in progress and mow the modified next model is under development.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3270-3275
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• 1994

Particle trajectory visualization using laser sheet was performed to investigate the corona wind flow interactions in the one-wire and two-wire type electrostatic precipitators. The corona wind generated by corona discharge was not negligible, and strong flow interactions took place owing to the induced circulatory cells. In the case of one-wire type, as the applied voltage was increased and the cross-section mean velocity was decreased, the effect of corona wind became active. In the case of two-wire type, if upstream discharge voltage was relatively higher than downstream discharge voltage, the effect of upstream corona wind was reduced.

• Archives of Reconstructive Microsurgery
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• v.24 no.1
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• pp.20-23
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• 2015

Despite increased utilization of microvascular anastomotic coupler (MAC) devices, the consequences have yet to be fully explored in terms of vascular regeneration. Removal of an exposed venous coupler is described herein, documenting normal circulatory flow through the remodeled site of application. A 25-year-old man who underwent open reduction and rigid fixation elsewhere for traumatic calcaneal fracture ultimately presented with a necrotic postoperative wound. The debrided defect was treated by free thigh perforator flap, incorporating a MAC device. Three months later, the flap remained viable, but the MAC itself was exposed. Structural integrity of the vessel and blood flow were sustained as the device was carefully removed, confirming true vascular remodeling in this example of MAC usage.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.361-366
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• 2003

For regenerative pump performance test we made 5 times enlarged and 3 different kinds blade types impeller with similarity. Due to geometrical characteristic of regenerative pump, there are two kinds of groups which effect on performance of it. One is geometric shape of impeller blade and the other is clearance and inlet/outlet head loss. To study performance of regenerative pump with impeller shape changes, we tested it with reducing clearance. And we reconcile performance data in the case of zero clearance and zero inlet/outlet head loss. Finally we could verify the influence of each group.

• The Korean Journal of Pain
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• v.9 no.1
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• pp.57-62
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• 1996

Stellate ganglion block(SGB) improves cutaneous blood flow of the head and neck region and upper extremity. For this reason, SGB has been performed in neural and circulatory disorders. But there is controversy on the cerebral blood flow regulation by sympathetic innervation. We investigated the hypothesis that cerebral blood flow could be affected by blocking ipsilateral sympathetic innervation of cerebral blood flow could be affected by blocking ipsilateral sympathetic innervation of cerebral vasculature. In 10 volunteers, the blood flow velocity and pulsatility index(PI) of middle cerebral artery(MCA) was measured using Transcranial Doppler Flowmeter, before and 15 minutes after SGB, at block side and opposite side. The blood flow velocity of MCA at block side was increased from $62.60{\pm}7.60$ cm/s to $72.80{\pm}8.01$ cm/s(P<0.01) and the PI at block side decreased from $0.75{\pm}0.12$ to $0.60{\pm}0.11$(P<0.05). But the blood flow velocity and PI at opposite side did not change. This study demonstrated that the cerebral blood flow could be increased by SGB, the preganglionic nerve fibers of which synapse with other cervical sympathetic ganglions.