• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.498-503
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• 2016

Many types of robot systems are used in the mass production line of thin film solar cells and flat panel displays. There are some issues such as the deflection and the vibration of the end-effector because robots handle large and heavy substrates at high speed. Heavy payload and high speed cause much vibration because the end-effector (fork) is made of carbon fiber reinforced polymer because of its light weightiness and sufficient stiffness. This study performs a dynamic simulation of an 8.5G solar cell substrate handling robot, including rigid and flexible bodies and a vibration controller. The fifth polynomial trajectory and the zero vibration derivative input shaping algorithm are applied. The vibration reduction is also proved in the experiments.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.92-92
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• 2011

IZTO and ITO thin films with a thickness of 200nm were deposited on Corning glass substrate to investigate the effects of substrate temperature on their electrical and optical properties by using pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt.%, ZnO 15 wt.%, SnO2 15 wt.%) and ITO (In2O3 90 wt.%, SnO2 10 wt.%). We investigated the structural, electrical, and optical properties of IZTO and ITO films. The structural and electrical properties of both films are sensitive on the substrate temperature. As the substrate temperature is increased, the electrical resistivity of ITO films is improved, but that of IZTO film increase over than $100^{\circ}C$. All IZTO and ITO thin films have good optical properties, which showed an average of transmittance over 80%. As a result, IZTO films can be a possible material for flexible display due to the low processing temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.93-93
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• 2011

The Indium Zinc Tin Oxide (IZTO) and Indium Tin Oxide (ITO) thin films are grown on PI substrate at different substrate temperature by pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt.%, ZnO 15 wt.%, SnO2 15 wt.%) and ITO (In2O3 90wt.%, SnO2 10wt.%). The structural, electrical, and optical properties are investigated. The IZTO thin films deposited at low temperature showed relatively low electrical resistivity compared to ITO thin films deposited at low temperature. As a result, we could prepare the IZTO thin films with the resistivity as low as $5.6{\times}10^{-4}({\Omega}{\cdot}m)$. Both of the films deposited on PI substrate showed an average transmittance over 80% in visible range (400.800nm). Overall, IZTO thin film is a promising candidate as an alternative TCO material to ITO in flexible and OLED devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.336-336
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• 2011

Over the past decades, organic semiconductors have been investigated intensely for their potential in a wide range of optoelectronic device applications since the organic materials have advantages for very light, flexible and low cost device fabrications. In this study, we fabricated small-molecule organic solar cells (OSCs) based on chloro[subphthalocyaninato]boron(III) (SubPc) as an electron donor and $C_{60}$ as an electron acceptor material. Recently SubPc, a cone-shaped molecule with $14{\pi}$-electrons in its aromatic system, has attracted growing attention in small-molecule OSC applications as an electron-donating material for its greater open-circuit voltage (VOC), extinction coefficient and dielectric constant compared to conventional planar metal phthalocyanines. In spite of the power conversion efficiency (PCE) enhancement of small-molecule OSC using SubPc and $C_{60}$, however, the study on the interface between donor-acceptor heterojunction of this system is limited. In this work, SubPc thin films at various thicknesses were deposited by organic molecular beam deposition (OMBD) and the evolution of surface morphology was observed using atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM). We also investigated the influence of film thickness and surface morphology on the PCE of small-molecule OSC devices.

• Journal of Sensor Science and Technology
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• v.15 no.6
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• pp.391-396
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• 2006

Free-standing multilayer distributed Bragg reflectors (DBR) porous silicon dielectric mirrors, prepared by electrochemical etching of crystalline silicon using square wave currents are treated with polystyrene to produce flexible, stable composite materials in which the porous silicon matrix is covered with caffeine-impregnated polystyrene. Optically encoded DBR PSi/polystyrene composite films retain the optical reflectivity. Optical characteristics of DBR PSi/polystyrene composite films are stable and robust for 2 hrs in a pH=7 aqueous buffer solution. The appearance of caffeine and change of DBR peak were simultaneously measured by UV-vis spectrometer and Ocean optics 2000 spectrometer, respectively.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.1
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• pp.13-16
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• 2018

Powdered infant formula is susceptible to oxidation in the presence of oxygen. Even though the product is usually packaged in nitrogen atmosphere, the oxygen ingress through the package layer may occur in case of flexible pouches and affects the oxidation of the product. $O_2$ barrier of the package is thus important variable to protect the product from oxidative deterioration. $O_2$ barrier property was investigated for aluminum-laminated small pillow packs of $3.5{\times}17.5cm$. Storage temperature and combination of primary and secondary packages were evaluated as variables affecting the barrier for conditions of empty pouch flushed with nitrogen. Apparent oxygen transmission rate of the primary package exposed to air was $2.32{\times}10^{-3}mL\;(STP)\;atm^{-1}\;d^{-1}$ at $30^{\circ}C$ and its temperature dependence could be explained by activation energy of $28.5kJ\;mol^{-1}$ in Arrhenius relationship. The additional secondary package of nylon/PE film containing 20 primary packages was ineffective in modulating package $O_2$ transmission and was only marginally helpful when combined with oxygen scavenger. The same was true in suppressing the product oxidation when the primary package was filled with 14 g of the formula.

• Macromolecular Research
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• v.13 no.1
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• pp.19-29
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• 2005

Polymer composites based on a thermotropic liquid-crystalline polymer (TLCP) and poly(butylene terephthalate) (PBT) were prepared using a melt blending process. Polymer composites consisting of bulk cheap polyester with a small quantity of expensive TLCP are of interest from a commercial perspective. The interactions between the PBT chains and the flexible poly(ethylene terephthalate) (PET) units in the TLCP phase resulted in an improvement in the compatibility of PBT/TLCP composites. TLCP droplets deformed and fragmented into smaller droplets in the PBT/TLCP composites, which resulted in TLCP fibrillation through the effective deformation of the TLCP droplets. The nucleation activities of the PBT/TLCP composites increased by adding even a small amount of the TLCP component.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.97-101
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• 2017

In this paper, IGZO thin film transistor (TFT) was fabricated with cross-linked Poly (4-vinylphenol) (PVP) gate dielectric for flexible, transparent display applications. The PVP is one of the candidates for low-temperature gate insulators. MIM structure was fabricated to measure the leakage current and evaluate the insulator properties according to the annealing temperature. Low leakage current ( <0.1nA/cm2 @ 1MV/cm ) was observed at $200^{\circ}C$ annealing condition and decreases much more as the annealing temperature increases. The electrical characteristics of IGZO TFT such as subthreshold swing, mobility and ON/OFF current ratio were also improved, which shows that the performance of IGZO TFTs with PVP can be enhanced by reducing the amount of incomplete crosslinking in PVP.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1173-1180
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• 2006

This study deals with fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) fan in an enclosure. The fluid flows were generated by a flexible PZT fan which deflects inside a fluid transport system of comparatively simple structure mounted on a PCB in an enclosure($270\times260\times90mm^3$). Input voltages of 30V and 40V, and a resonance frequency of 28Hz were used to vibrate the cooling fan. Input power to the module was 4W. The height in an enclosure was changed 23$\sim$43mm. The fluid flow around the module was visualized by using PIV system. The temperature distributions around a heated module were visualized by using liquid crystal film. As the height in an enclosure and the input voltage of PZT fan increased, the cooling effect of module using a PZT fan increased. We found that the flow type was T- or Y-shape and the cooling effect was increased by the wake generated by a PZT fan.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1073-1078
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• 2003

This paper presents the vibration characteristics of a cantilever beam in contact with a fluid using a PZT actuator and PVDF film. dynamic behaviors of a flexible beam-water interaction system are examined. The effect of the liquid level on free vibration of the composite beam in a partially liquid-filled circular cylinder is investigated. The coupled system is subject to an undisturbed boundary condition un the fluid domain. In the vibration analysis of a wetted beam. the decoupled analyses between beam and fluid have been conventionally employed by considering first the composite beam vibration in the all and secondly Performing the correction taking account for surrounding fluid effects. That is, this investigation was to look at how natural frequencies, mode shapes. and damping are affected by liquid level variations. The signals from the sensor according to the applied input voltage are digitalized and filtered in order to obtain the dynamic characteristics of the composite beam in contact with fluid. It was found that the coupled natural frequencies decreased with the fluid level for the identical composite beam due to added mass effect. In case of the free-free boundary condition, the natural frequency gently decreased at fluid water level between 20% and 80% in the first tending mode and we found out the bends of stair shape for added mass effect of the fluid.