• Journal of ILASS-Korea
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• v.6 no.4
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• pp.14-21
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• 2001

Rotary atomizer is widely used in practical application ranging from combustion, cooling, spray drying, agriculture, chemical system. Rotary cup atomizer has some advantages such as extreme versatility and liquid atomization successfully varying widely in viscosity. In rotary atomization, the feed liquid is centrifugally accelerated to high velocity and the liquid extends over the rotating surface as a thin film before being discharged into an atmosphere. The degree of rotary atomization depends upon peripheral speed, feed rate, liquid properties and atomizer design. An important asset is that thickness and uniformity of the liquid sheet can readily be controlled by regulating the liquid flow rate and the rotational speed. LDPA(Laser Diffraction Particle Analyser) and image aquisition system are used to measure drop size distribution and spray pattern. The atomization characteristics of the rotary cup atomizer is investigated experimentally by varing the liquid feed rate, rotary cup speed and air velocity for atomization. As a results, the effect of air velocity on the atomization characteristics such as drop size and spray uniformity is considerably greater than variation of those with liquid feed rate.

• Journal of Information Display
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• v.10 no.3
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• pp.131-136
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• 2009

This is a report on the fabrication of a flexible OTFT backplane for electrophoretic display (EPD) using a printing technology. A practical printing technology for a polycarbonate substrate was developed by combining the conventional screen and inkjet printing technologies with the wet etching and oxygen plasma processes. For the gate electrode, the screen printing technology with Ag ink was developed to define the minimum line width of ${\sim}5{\mu}m$ and the thickness of ${\sim}70nm$ with the resistivity of ${\sim}10^{-6}{\Omega}{\cdot}cm$, which are suitable for displays with SVGA resolution. For the source and drain (S/D) electrodes, PEDOT:PSS, whose conductivity was drastically enhanced to 450 S/cm by adding 10 wt% glycerol, was adopted. In addition, the modified PEDOT:PSS could be neatly confined in the specific S/D electrode area that had been pretreated with oxygen. The OTFTs that made use of the developed printing technology produced a mobility of ${\sim}0.13cm^2/Vs.ec$ and an on/off current ratio of ${\sim}10^6$, which are comparable to those using thermally evaporated Au for the S/D electrode.

• Journal of Information Display
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• v.10 no.3
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• pp.117-120
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• 2009

A new crystallization method for amorphous silicon, called selective area heating (SAH), was proposed. The purpose of SAH is to improve the reliability of amorphous silicon films with extremely low thermal budgets to the glass substrate. The crystallization time shortened from that of the conventional solid-phase crystallization method. An isolated thin heater for SAH was fabricated on a quartz substrate with a Pt layer. To investigate the crystalline properties, Raman scattering spectra were used. The crystalline transverse optic phonon peak was at about 519 $cm^{-1}$, which shows that the films were crystallized. The effect of the crystallization time on the varying thickness of the $SiO_2$ films was investigated. The crystallization area in the 400nm-thick $SiO_2$ film was larger than those of the $SiO_2$ films with other thicknesses after SAH at 16 W for 2 min. The results show that a $SiO_2$ capping layer acts as storage layer for thermal energy. SAH is thus suggested as a new crystallization method for large-area electronic device applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.13-13
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• 2010

Piezoelectric sensors are extensively used to measure force because of their high sensitivity and low cost. however, the development of device with reduced size but with improved sensitivity is highly important. Low-temperature co-fired ceramic (LTCC) is one of promising materials for this application than a silicon substrate because it has very good electrical and mechanical properties as well as possibility of making various three dimensional (3D) structures. In this work, piezoelectric pressure sensors based on hybrid LTCC technology were presented. The LTCC diaphragms with thickness of $400\;{\mu}m$ were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The piezoelectric sensing layer consists of PZT thin film deposited by RF magnetron sputtering method on between top and bottom Au electrodes. The PZT films deposited on LTCC diaphragms were successfully grown and were analyzed by using X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.130-131
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• 2008

Chalcogenide glass has been known for many photo induced phenomena and superial electron / optical specific by structure flexibility, unique electronic configuration. It is become known to the greatest specific as photonic material medium that possible to perfect controlling by continuity and photo inducing direction of amorphous chalcogenide. In our experiment, we choose the amorphous As-Ge-Se-S and coming glass as a substrate. And then we have evaporated in the ${\sim}2{\times}10^{-6}$ Torr using a E-beam evaporator, completed thin film sample that have 1um thickness of As-Ge-Se-S 600 $\AA$, 10~5 $\AA$/s. At first, we let the change the angle between laser and sample by holography litho method and then, expect that satisfied conclusion which 2-dimension diffraction lattice manufacture and specifics by investing a He-Ne laser for 2000 seconds.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.581-589
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• 1994

Magnetic properties and microstructures of the $Co_{83}Cr_{17}$ films growing under the applied magnetic field were studied. In comparison, those of the films growing without magnetic field were also studied. Magnetic field does not affect saturation magnetization and in-plane coercivity of the films. On the contrary perpendicular coercivity and effective perpendicular anisotropy field decreased. Grain size and the thickness of the so-called transition layer were not affected and the C-axis alignment of the films was slightly deteriorated due to magnetic field. Also, microstructures of the sputtered films showed larger grain sizes of strong (002) preferred orientation for thicker film specimens independent of applied magnetic field.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1353-1361
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• 1992

Holographic optical element(HOE) is fabricated with the properties of lightweight, thin thickness and interconnectivity for free space. Particularly, HOE for optical interconnection and multiple image processing should have a high efficiency and equal spot intensity, Nonlinear equations for 2-dimensional binary phase grating(BPG) structure is solved by computer simulation based on modified Newton method. Computer-generated pattern drawn by plotter is scaled down and translated into the microfilm. After contact printing between the microfilm and silver halide hologram film, phase diffraction grating produces the $5{\times}5$ multiple spots. Experimental results are shown that bleached phase grating has a high efficiency and equal focused beams except central zero order.

• Electrical & Electronic Materials
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• v.7 no.1
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• pp.57-63
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• 1994

Aluminum oxide($Al_2{O_3}$) offers some unique advantages over the conventional silicon dioxide( $SiO_{2}$) gate insulator: greater resistance to ionic motion, better radiation hardness, possibility of obtaining low threshold voltage MOS FETs, and possibility of use as the gate insulator in nonvolatile memory devices. We have undertaken a study of the dielectric breakdown of $Al_2{O_3}$ on Si deposited by GAIVBE technique. In our experiments, we have varied the $Al_2{O_3}$ thickness from 300.angs. to 1400.angs. The resistivity of $Al_2{O_3}$ films varies from 108 ohm-cm for films less than 100.angs. to 10$_{13}$ ohm-cm for flims on the order of 1000.angs. The flat band shift is positive, indicating negative charging of oxide. The magnitude of the flat band shift is less for negative bias than for positive bias. The relative dielectric constant was 8.5-10.5 and the electric breakdown fields were 6-7 MV/cm(+bias) and 11-12 MV/cm (-bias).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.287-287
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• 2010

We report a new direct patterning method, called liquid bridge-mediated nanotransfer molding (LB-nTM), for the formation of two- or three-dimensional structures with feature sizes between tens of nanometers and tens of micron over large areas. LB-nTM is based on the direct transfer of various materials from a mold to a substrate via a liquid bridge between them. This procedure can be adopted for automated direct printing machines that generate patterns of functional materials with a wide range of feature sizes on diverse substrates. Arrays of TIPS-PEN TFTs were fabricated on 4" polyethersulfone (PES) substrates by LB-nTM using PDMS molds. An inverted staggered structure was employed in the TFT device fabrication. A 150 nm-thick indium-tin oxide (ITO) gate electrode and a 200 nm-thick SiO2dielectric layer were formed on a PES substrate by sputter deposition. An array of TIPS-PEN patterns (thickness: 60 nm) as active channel layers was fabricated on the substrate by LB-nTM. The nominal channel length of the TIPS-PEN TFT was 10 mm, while the channel width was 135 mm. Finally, the source and drain electrodes of 200 nm-thick Ag were defined on the substrate by LB-nTM. The TIPS-PEN TFTs can endure strenuous bending and are also transparent in the visible range, and therefore potentially useful for flexible and invisible electronics.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.84-88
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• 2013

These days embedded technology may be the most significant development in the electronics industry. The study focused on the development of active device embedding using flexible printed circuit in view of process and materials. The authors fabricated 30um thickness Si chip without any crack, chipping defects with a dicing before grinding process. In order to embed chips into flexible PCB, the chip pads on a chip are connected to bonding pad on flexible PCB using an ACF film. After packaging, all sample were tested by the O/S test and carried out the reliability test. All samples passed environmental reliability test. In the future, this technology will be applied to the wearable electronics and flexible display in the variety of electronics product.