• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.455-463
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• 2002

Ionic Polymer metal composite(IPMC), one of new actuation materials of EAPs is fabricated by electroless plating of platinum on both sides of the perfluorosulfonic acid film or Nafion film and its electromechanical characteristics are investigated. The IPMC strip bends towards anode under electrical field. As the number of plating cycle increases, the distance between plated platinum electrodes on both sides of Nafion membrane decreases and also the displacement is almost inversely proportional to the number of plating. The displacement of IPMC strip depends on voltage magnitude and applied signal frequency and its maximum deformation is observed at a critical frequency, resonant frequency. Low pressure sandblasting is used for surface treatment of Nafion membrane and at 8 times of plating cycle produced actuator with high displacement performance. For more efficiency of fabricated IPMC, it is useful to add one or two surface developing step which is the second reduction process using hydrazine.

• Journal of Biomedical Engineering Research
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• v.27 no.4
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• pp.143-153
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• 2006

The purpose of this work was to assess and quantify the beneficial effects of gas exchange, while testingto the various frequencies of the sinusoidal wave that was excited by the PZT actuator, for patients suffering from acute respiratory distress syndrome (ARDS) or chronic respiratory problems. Also, this paper considered a simulator to design a hollow type artificial lung, and a mathematical model was used to predict a behavior of blood. This simulation was carried out according to the Montecarno's simulation method, anda fourth order Runge-Kutta method was used to solve the equation. The experimental design and procedure are then applied to the construction of a new device to assess the effectiveness of the membrane vibrations. As a result, the vibration method is very effective in the increase of gas transport. The gas exchange efficiency for the vibrating intravascular lung assist device can be increased by emphasizing the following design features: consistent and reproducible fiber geometry, and most importantly, an active means of enhancing convective mixing of water around the hollow fiber membranes. The experimental results showed the effective performance of the vibrating intravascular lung assist device. Also, we concluded that important design parameters were blood flow rates, fiber outer diameter and oxygen pressure drop. Based on the present results, it was believed that the optimal level of blood flow rates was 200$cm^3$/min.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.533-541
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• 1995

We recently developed a new model of moving actuator type totally implantable artificial heart[TIAH , based on the reverse position of the aortic and pulmonary conduits. This concept was proposed by one of surgeons in our team[Joon-Ryang Rho, M.D. to facilitate anatomical fitting of TIAHs. The moving actuator type electromechanical TIAH consisted of the left and right blood sacs, and the moving actuator including a motor. The inverted umbrella type polyurethane valves were used in the blood pumps. The aortic conduit was positioned anterior to the pulmonary conduit, which was the opposite relation to the conventional configuration of other total artificial hearts. We also adapted slip-in connectors for the aortic and pulmonary conduits. Two sheep , weighing 60-69 kg, were used for implantation. After small cervical incision and trans-sternal bilateral thoracotomy, cardiopulmonary bypass [CPB was administered using an American Optical 5-head pump and a membrane oxygenator[Univox-IC, Bentley . The anterior and posterior vena cavae were drained separately for venous return. An arterial return cannula was inserted into the right common carotid artery. During CPB, almost all of the ventricular myocardium was excised down to the atrioventricular groove and the artificial heart was implanted. We achieved 3-day survival in the first sheep and 2-day survival in the second. The day after operation the first sheep was successfully extubated and the second sheep was weaned from a respirator with good condition. After extubation, the first sheep walked around in the cage and fed herself. Serial laboratory and hemodynamic examinations were done during the experiments. In both sheep, pulmonary dysfunction was gradually developed, which was accompanied by acute renal failure. The animals were sacrificed and autopsy was done. Unexpected pregnnacy was incidentally found in both sheep. To our knowledge this is the first report of significant survival cases in the orthotopic implantation of electric TIAH using sheep.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.294-298
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• 2008

The ionic polymer-metal composite actuators with selectively grown multiple electrodes were developed to mimic the swimming locomotion of a fish. The developed method is based on combining electroplating with the electroless chemical reduction using the patterned mask. The advantages of this fabrication method are that the initial compositing between the polymer and platinum particles can be assured by the chemical reduction method, and the thickness of each electrode can be controlled easily and rapidly by electroplating. By using the fabricated actuator with a multiple degree of freedom, the oscillatory wave of the flexible membrane actuator was generated and a twisting motion was also realized to verify the possibility of mimicking the fish-like locomotion. The frequency response function was analyzed to investigate the natural frequency and the damping factor by a mechanical shaker and direct electrical excitation through the swept-sine method. Present results show that this novel method can be a promising technique to easily pattern each of multiple electrodes and to implement the biomimetic motion of the polymer actuators with good mechanical bending performance.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.497-501
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• 2000

Flow over a sphere is controlled experimentally at $Re=10^5$ using electro-magnetic actuators. The electro-magnetic actuator developed in this study is composed of the permanent magnet electro-magnet membrane and slot. Eight actuators are placed inside the sphere at equally spaced intervals on a latitudinal plane and the position of the control slot is 76 from the stagnation point. Each actuator generates a periodic blowing and suction through the slot at variable frequencies of $10{\sim}140Hz$ and variable amplitudes by controlling electric signals applied to the electro-magnet. Drag on the sphere measured using a load cell is significantly reduced with control at the forcing frequencies larger than the natural shedding frequency $({\approx}14Hz\;at\;Re=10^5)$, whereas drag is slightly increased at the forcing frequency of 10Hz. It is shown from pressure measurement that the static pressure in the rear surface of the sphere is significantly increased with control, indicating that the separation is delayed due to control. Flow visualizations also show that the detaching shear layer is more attracted to the sphere center with control, the separation bubble size is significantly reduced, and motion inside the bubble is very weak, as compared to the case of uncontrolled flow.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.340-341
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• 2005

Three different composition 130um thickness PZT were fabricated by extrusion method and burned out at $550^{\circ}C$ and sintered at $1260^{\circ}C$/2.5hrs. Actuator was fabricated using glass and Si(100) wafer by MEMS process. From XRD data, in case of DECH, perovskite phase peak strength is higher than others. We were able to obtain the information of grain growth and porosity by SEM images. Also DECH PZT on glass membrane(100um thickness) have larger displacement than others.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.197-201
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• 2002

This paper presents optimized design, fabrication and thermal characteristics of micro-heaters for thermal MEMS (micro electro mechanical system) applications using SOI and trench structures. The micro-heaters are based on a thermal measurement principle and contains thermal isolation regions of 10 ${\mu}m$-thick Si membranes consisting of oxide-filled trenches in the SOI membrane rim. The micro-heaters were fabricated with Pt-RTD on the same substrate via MgO buff layer between Pt thin-film and $SiO_2$ layer. The thermal characteristics of micro-heater with trench-free SOI membrane structure was $280^{\circ}C$ at input power 0.9 W; in the presence of 10 trenches, it was $580^{\circ}C$ due to reduction of the external thermal loss. Therefore, a micro-heater with trenches in SOI membrane rim structure provides a powerful and versatile alternative technology for enhancing the performance of micro-thermal sensors and actuators.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.316-317
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• 2009

The ion-exchange membrane, Nafion, remains as the benchmark for a majority of research and development in IPMC technology. In this research, we employed a novel ionomer named by sulfonated poly(styrene-ran-ethylene) (SPSE) that is crosslinked by UV irradiation. The sulfonic acid groups were stable during the UV irradiation crosslinking process. Water uptake, ion exchange capacity, and proton conductivity are characterized for both pure SPSE and crosslinked SPSE membrane. The bending responses of SPSE actuators under both direct current (DC) and alternating current (AC) excitations were investigated. The voltage-current behaviors of the actuators under AC excitations are also measured. Results showed the crosslinked SPSE actuators have better electromechanical performance than that of pure SPSE actuator with regard to tip displacement as a novel smart material.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1332-1335
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• 2003

This paper presents the enhancement of oxygen transfer efficiency using the vibrating intravascular lung assist device (VIVLAD) in in-vitro experiments for patients having chronic respiratory problems. The test section was a cylinder duct with the inner diameter of 30 mm. The flow rate was controlled by the pump and monitored by a built-in flow meter. The vibration apparatus was composed of a piezo-vibrator, a function generator. and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 l/min through the 120-cm-Jong hollow fibers have been achieved by exciting a piezo-vibrator. The output of PVDF sensor were investigated by various frequencies in VIVLAD. The experimental results showed that VIVLAD would be enhance oxygen transfer efficiency.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.167-169
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• 2008

A 1.2KW Proton Exchange Membrane Fuel Cell(PEMFC) stack(Nexa Power Module) is installed to motor driven general scooter. The 24V, 650W BLDC motor is used for actuator and 2nd battery(24V, 4Ah) is used for stable starting of this motor. The operating information of Nexa Power Nodule is transmitted by RS-232 serial communication to notebook PC, and that data is analysed and displayed by the LabVIEW monitoring system.