• Journal of Magnetics
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• v.22 no.2
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• pp.344-351
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• 2017

Wireless magnet pumps are used in medical applications and are particularly useful as artificial heart ventricular assist devices (VADs). To investigate wireless operation of magnetic pumps, we fabricated three types of magnetic impellers using bonded magnets by blending magnetic powders of SmFeN, NdFeB, and Sr-ferrite. We investigated the magnetic properties of the fabricated magnetic impellers, which are driven by the application of magnetic coupling with an external driving magnet or external coil system, without a driving motor, shaft, or mechanical bearings. The use of wireless magnetic pumps is therefore not complicated by critical issues of size, heat, and vibration, which are very important issues for blood pumps. The magnetic properties of the impellers, such as their rotational speed, driving torque and hydrodynamic performance, determine their wireless driving ranges. We conducted performance evaluations of the impeller's magnetic wireless manipulation, heat, and vibration. In addition, we carried out an animal test to confirm the suitability of the wireless magnetic pumps for use as biventricular assist devices (BiVADs).

• Journal of Power System Engineering
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• v.10 no.4
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• pp.153-158
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• 2006

최근 임상용 LVAD의 계속된 발전으로 인해 환자들의 삶이 연장되었다. 그러나 LVAD가 환자의 삶을 연장하였지만, 우심실 심부전증을 야기 시켰고, 결론적으로 환자들은 RVAD가 필요하게 되었다. 이러한 이유로 장시간 사용할 수 있는 BVAD의 도입이 요구 되어졌다. 최근 BVAD에 관련된 연구들을 보면 장시간 사용을 위한 원심 BVAD의 디자인과 BVAD에서의 누수 정도를 파악하는데 목적을 두고 있다. 따라서 본 논문에서는 BVAD의 누수를 파악하기 위한 속도 데이터와 용적당 흐름 비율의 계산을 CFD를 사용하여 해석적으로 조사하고자 하였다. CFD의 해석 결과 틈새부위의 회전수가 증가 할수록 혈액의 흐름을 방해하는 역류가 증가하고 유량도 줄어들어, 틈새부위의 누수량이 회전속도의 변화에 의존된다는 것을 확인 할 수 있었다.

• 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 KOSOMBE Conference
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• v.1996 no.05
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• pp.207-212
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• 1996

We developed pneumatic blood pump and its driving system as a pediatric ventricular assist device. The blood pump is diaphragm type system and its blood contacting area is coated with Bio-Span. The driving unit Is consists of dual pumps, valves for the reliable blood pumping and its controller uses 80C196(Intel) as a main processor. The acute animal experiment was performed with dogs and its body weight is about 20 kg. The maximum cardiac output is about 2.1 l/min and the pressure and flow curves showed reliable operation as assist device.

• Journal of computational fluids engineering
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• v.21 no.1
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• pp.103-109
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• 2016

With the rapid increase in the number of patients with cardiopulmonary diseases, more cardiopulmonary circulatory assist devices are also needed. These devices can be employed when heart and/or lung function poorly. Due to the critical role they take, these devices have to be designed optimally from both mechanical and biomechanical aspects. This paper presents the CFD results of a baseline model of a centrifugal blood pump for the ECMO condition. The details of flow characteristics of the baseline model together with the performance curves and the modified index of hemolysis(MIH) are investigated. Then, the geometry of baseline impeller and the volute are modified in order to improve the biomechanical performance and reduce the MIH value. The numerical simulations of two cases represent that when impeller radius and prime volume decrease the MIH value also decreases. In addition, the modified geometry shows more uniform pressure distribution inside the volute. The findings provide valuable information for further modification and improvement of centrifugal blood pumps from both mechanical and biomechanical aspects.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.559-564
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• 2001

In order to apply into a compact and reliable centrifugal blood pump, this paper introduces a self-bearing motor in which a rotor is rotated without contact. The rotor is actively controlled in only radial directions, while the axial and tilting motions are passively stable owing to the disk-shape structure of the rotor. A prototype was made in outer-rotor type that is far better in the compactness than inner-rotor type. The prototype could be driven up to 8000 rpm with the rotor vibration under 0.12mm. The maximum cardiac output and pressure head were 9 L/min and over 200 mmHg, respectively. These experimental results show that the proposed self-bearing motor has sufficient performance for application to a real blood pump.

• Journal of Chest Surgery
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• v.15 no.1
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• pp.35-39
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• 1982

Cold blood potassium cardioplegia, by two types of the infusion systems, was used in 45 patients who were undergone the open cardiac operation. Method A [in 25 patients] was the syringe infusion system and method B [in 20 patients] was the pump infusion system. Cold blood potassium cardioplegic solution was used less amount on method B than method A. Serum potassium was often increased significantly on method A as a result of excessive infusion of cold blood potassium cardioplegic solution. But method B, excessive infusion of cold blood potassium cardioplegic solution was prevented by reperfusion of the previous infused cold blood potassium cardioplegic solution through the recirculation system. Alteration of infused rate and concentration of potassium in cold blood potassium cardioplegic solution during infusion [which might be suggested on the method A] could be controlled on method B.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.353-362
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• 2000

Minimization of hemolysis is one of the key factors for successful axial flow blood pumps. It is, however, difficult to estimate the hemolytic performance of axial flow blood pumps without experiments. Instead, the Computational Fluid Dynamics(CFD) analysis enables the prediction of hemolysis. Three-dimensional fluid dynamics of axial flow pumps with different impellers were analyzed using the CFD software, FLOTRAN. The turbulence model k-$\varepsilon$ was used. The changes in turbulent kinetic energy applied to each particle (red blood cell) flowing through the pumps were computed and displayed by the particle trace method (particle spacing of 10 msec). Also, the Reynolds shear stress was calculated from the turbulent kinetic energy. The shear stress was higher behind the impellers than elsewhere. The CFD analysis could predict in vitro results of hemolysis and also the areas where hemolysis occurred. The CFD analysis was found to be a useful tool for designing less hemolytic rotary blood pumps.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.247-250
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• 1995

The purpose of this paper is to develop diaphragm-type pneumatic ventricular assist device(VAD) for clinical application and to evaluate its performance through the mock circulation system. The blood housing and diaphragm are made by coating pellethane on the metallic mold and the back plate is made by machining process. The relations of cardiac output(CO) vs. beat rate and CO vs. systolic-to-diastolic rate was estimated through the mock test and hemodynamic waves are recorded for the evaluation of VAD. As a result, the volume of blood pump is 70 ml, maximum CO is 5 L/min and CO has a close relation to the input resistance of blood pump. The hemodynamic data and waves showed this system can be applicable to the animal experiment.

• Journal of Yeungnam Medical Science
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• v.28 no.2
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• pp.124-132
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• 2011

Background: Antiplatelet agent administration is critical in managing coronary-artery disease, but there is a concern regarding operation-related bleeding and an increase in blood transfusion in such, especially when delivering combined antiplatelet agents. This study was conducted to evaluate the effect of the administration of antiplatelet agents on off-pump coronary-artery bypass surgery (OPCAB). Methods: From March 2003 to December 2009, 49 patients who had undergone OPCAB were collected retrospectively. The patients were divided into three groups according to the administration of antiplatelet agents before the OPCAB operation: 21 patients were given an aspirin agent (group 1), 19 patients were given combined agents (aspirin+clopidogrel) (group 2), and nine patients were not given any antiplatelet agent (group 3). The three groups' perioperative hematologic and coagulation profiles, including their platelet counts, hemoglobin levels, hematocrit, prothrombin times, and aPTTs (activated partial thromboplastin times), and their postoperative bleeding, related complications, transfusion requirements, and operation times, were compared. Results: The operation time in group 2 was 4.3 hours, longer than those in the two other groups, and urgent operation was significantly most frequent in group 2 (63%). The amount of blood loss and the number of patients who received blood transfusion were not different in the three groups. The perioperative hemoglobin level, hematocrit, platelet count, prothrombin time, and aPTT were also not significantly different among the three groups. Conclusion: The continuous administration of antiplatelet agents to the patients in this study did not increase their postoperative bleeding or operation-related complications. Therefore, OPCAB may well be considered even if combined antiplatelet agents are being administered.