Chul-Jin Kim

Effects of catalyst and solvent on PbTiO3 fibers prepared from triethanolamine complexed titanium isopropoxide

Sol-gel processing was used to prepare lead titanate fibers. Titanium isopropoxide and lead acetate trihydrate were used as starting materials and triethanolamine (TEA) was added to form stabilized Pb-Ti complex alkoxide. Effects of catalyst and solvent on the state of precursor solutions, gelation reaction, fiber spinnability, pyrolysis and crystallization were investigated.

Preparation of PbTiO3 fibres using triethanolamine-complexed alkoxide

Abstracts are not published in this journal

Preisach modeling of dielectric elastomer EAP actuator

DE EAP(Dielectric Elastomer ElectroActive Polymer) has advantages in its weight, ease of fabrication and low power consumption. There are many efforts applied to various field in recent ten years. But the present modeling is not enough to appear its characteristics because of its hysteresis. In this paper, we propose modeling of DE EAP with Preisach Model that is used in order to model the hysteretic response arising in PZT and SMA. The modeling of DE EAP with Presach model is verified by experiment with various DE EAP actuators.

A model of the IPMC actuator using finite element method

Ionic polymer-metal composite (IPMC) is an attractive actuator among many electro-active polymers. In order to improve the performance of IPMC actuator, an IPMC actuator with the patterned surface was proposed. It is named the patterned IPMC actuator. In order to make use of its maximum effect, it is needed to establish a valid mathematical model. Among many models of IPMC actuator, the grey box modeling proposed by Kanno et al. was suited to model the patterned IPMC actuator. In this paper, we applied the grey box model based on Kannos model. Theoretical and experimental results demonstrate that the model is practical and effective enough in predicting the bending displacement partly.

Performance enhancement of IPMC by anisotropic plasma etching process

Ionic Polymer-Metal Composites (IPMCs) of EAP actuators is famous for its good property of response and durability. The performance of Ionic Polymer-Metal Composites (IPMCs) is an important issue which is affected by many factors. There are two factors for deciding the performance of IPMC. By treating anisotropic plasma etching process to 6 models of the IPMCs, enhanced experimental displacement and force results are obtained. Plasma patterning processes are executed by changing the groove and the land length of 6 patterns. The purpose of the present investigation is to find out the major factor which mainly affects the IPMC performance. Simulations using ANSYS have been executed to compare with the experimental results about the values and the tendency of data. Experimental and simulating data of the performances seem to have similar tendency. In the next part of the paper, we observed the other properties like capacitance, resistance and stiffness of 6 plasma patterned IPMCs. And we observed that the stiffness is the major factor which affects the performance of IPMCs. As we seen, our problem has been reduced to investigate about the property of stiffness. We suggest that the stiffness is largely changed mainly because of the different thickness of Platinum stacked of the groove and the land part which are produced by anisotropic plasma etching processes. And we understand that anisotropic plasma patterned IPMCs of better performance can be applied to various applications.

Preisach modeling of IPMC-EMIM actuator

The IPMC-EMIM actuator is an improved IPMC actuator to replace the water by stable ionic liquids (1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EtMeIM][TA])). Just as a general IPMC actuator which uses the solvent of water has hysteresis, so do the IPMC-EMIM actuator exhibits hysteresis like other smart materials such as piezoceramics (PZT), magnetostrictive materials, and shape memory alloys (SMA). Hysteresis can cause it to be unstable in closed loop control. The Preisach Model has been used to model the hysteretic response arising in PZT and SMA. Noting the similarity between IPMC-EMIM and other smart materials, we apply the Preisach model for the hysteresis in the IPMC-EMIN actuator. This paper reviews the basic properties of the Preisach model and confirms that the Preisach model of IPMC-EMIM actuator is possible.

Performance improvement of IPMC using resonance frequency

Ionic polymer metal composites is the proposing material for applications, since it has many attractive qualities that are durability, aquatic, miniature and light-weighted. Especially, IPMC has extraordinary advantages that are large displacement at low driving voltage(~3V), low power consumption and simple structure. However, slow time response prevents IPMC from various applications. Since IPMC is generally used in simply-supported configuration, which has same characteristic with a cantilever beam, IPMC has natural frequency and it oscillates extremely at natural frequency. We propose new open loop control method based on frequency response, which is combined with conventional DC input. This method is experimentally tested and compared with result by conventional input.

Design and control of 2-axis tilting actuator for endoscope using ionic polymer metal composites

In field of endoscopy, in order to overcome limitation in conventional endoscopy, capsule endoscope has been developed and has been recently applied in medical field in hospital. However, since capsule endoscope moves passively through GI tract by peristalsis, it is not able to control direction of head including camera. It is possible to miss symptoms of disease. Therefore, in this thesis, 2-Axis Tilting Actuator for Endoscope, based on Ionic Polymer Metal Composites (IPMC), is presented. In order to apply to capsule endoscope, the actuator material should satisfy a size, low energy consumption and low working voltage. Since IPMC is emerging material that exhibits a large bending deflection at low voltage, consume low energy and it can be fabricated in any size or any shape, IPMC are selected as an actuator. The system tilts camera module of endoscope to reduce invisible area of the intestines and a goal of tilting angle is selected to be an angle of 5 degrees for each axis. In order to control tiling angle, LQR controller and the full order observer is designed.

Design and Position Control of AF Lens Actuator for Mobile Phone Using IPMC-EMIM

IPMC-EMIM (Ionic Polyer Metal Composites + 1-ethyl-3- methyl imidazolium trifluromethane sulfonate, EMIM-Tfo) is fabricated by substituting ionic liquid for water in Nafion film, which improves water sensitiveness of IPMC and guarantees uniform performance regardless of the surrounding environment. In this paper, we will briefly introduce the procedure of fabrication of IPMC-EMIM and proceed to introduce the Hook-type actuator using IPMC-EMIM and application to AF Lens actuator. Parameters of Hook-type actuator are estimated from experimental data. In the simulation, The proposed AF Lens Actuator is assumed to be a linear system and based on estimated parameters, PID controller will be designed and controlled motion of AF Lens actuator will be shown through simulation.

Small form factor (SFF) optical data storage devices for mobile applications

There are two basic requirements in the field of optical storage data devices. The first is the demand for the improvement of memory capacity to manage the increased data capacity in personal and official purposes. The second is the demand for small sized optical storage devices for mobile multimedia digital electronics, including digital camera, PDA and mobile phones. To summarize, for the sake of mobile applications, it is necessary to develop optical data storage devices which have simultaneously a large capacity and a small size. Small form factor optical disk drive (SFF ODD) is expected to become a good match for mobile applications due its advantages over other devices in cost and removability. Nowadays, many companies and research institutes including universities cooperate together in the research on SFF ODD and other related optical storage devices. Due such active researches, it is expected that SFF ODD will be widely used in mobile applications in the very near future.