• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.203-203
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• 2009

Low temperature annealing for oxide TFTs including IGZO on PI substrate is the essential process to fabricate flexible display devices, since low heat-resistance on PI and PEN substrates limits the temperature range. Laser annealing is one of the promising candidates for low temperature process, and it has been used for various application in semiconductor and LCD fabrication. We irradiated laser to solution-based IGZO thin films on PI substrate were irradiated to laser beam, and investigated laser damage of PI layer. Based on transmittance analysis, wavelength(532nm) and scan speed(1000mm/s) is the optimized condition for laser irradiation about ink-Jet printed oxide TFTs on PI substrates.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.677-681
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• 2013

Apart from the deposition of alignment layer, alignment process needs to be involved for alignment of liquid crystal (LC) molecules. To simplify manufacturing process, several method were used such as rubbing, ion-beam irradiation, UV irradiation, and lithography. But, eventually it needs another treatment for LC alignment. Here, we suggested Si induced polyimide (PI) alignment layer at low temperature. Using this method, we are able to eliminate the alignment process and found that the alignment and electro-optic performance are much better than that of the rubbed PI LC cells. Compared to the rubbed PI cells, the response time was decreased by 70% and C-V characteristics have hysteresis-free.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.47-52
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• 2001

We investigate the variation in the shape of confusion circle as the real amplitude distribution of incident beam in pupil area is shifted and the effect of the shift of incident beam on the astigmatism for eye. The shifted magnitudes of Incident beam are 0.0, 0.25, 0.5 and 0.75 and the shifted direction of incident beam ${\pi}/2$. We also consider the optical system having the astigmatism which are $0.0{\lambda}$, $0.25{\lambda}$, $0.5{\lambda}$ and $0.75{\lambda}$. As the shifted magnitude of the real amplitude distribution of incident beam increases, the shape of confusion circle on the image surface transfers from the rotational symmetry to the asymmetry like ellipse and the length of the major axis for confusion circle on the Image surface increases. We know from results in this paper that the shift of the incident beam in pupil area compensates the effect of astigmatism and the real amplitude distribution of incident beam in pupil area is shifted to minimize the effect of astigmatism for eye.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.41-41
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• 2008

In general, polyimides (PIs) are used in alignment layers in liquid crystal displays (LCDs). The rubbing alignment technique has been widely used to align the LC molecules on the PI layer. Although this method is suitable for mass production of LCDs because of its simple process and high productivity, it has certain limitations. A rubbed PI surface includes debris left by the cloth, and the generation of electrostatic charges during the rubbing induces local defects, streaks, and a grating-like wavy surface due to nonuniform microgrooves that degrade the display resolution of computer displays and digital television. Additional washing and drying to remove the debris, and overwriting for multi-domain formation to improve the electro-optical characteristics such as the wide viewing angle, reduce the cost-effectiveness of the process. Therefore, an alternative to non-rubbing techniques without changing the LC alignment layer (i.e, PI) is proposed. The surface of LC alignment layers as a function of the ion beam (IE) energy was modified. Various pretilt angles were created on the IB-irradiated PI surfaces. After IB irradiation, the Ar ions did not change the morphology of the PI surface, indicating that the pretilt angle was not due to microgrooves. To verify the compositional behavior for the LC alignment, the chemical bonding states of the ill-irradiated PI surfaces were analyzed in detail by XPS. The chemical structure analysis showed that ability of LCs to align was due to the preferential orientation of the carbon network, which was caused by the breaking of C=O double bonds in the imide ring, parallel to the incident 18 direction. The potential of non-rubbing technology for fabricating display devices was further conformed by achieving the superior electro-optical characteristics, compared to rubbed PI.

• Journal of Radiation Industry
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• v.4 no.4
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• pp.335-339
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• 2010

In this study, the surface of polyimide (PI) films was modified using ion implantation to enhance its adhesion to a deposited copper (Cu) layer. The surfaces of the PI films were implanted with 150 keV $Xe^+$ ions at fluences varying from $1{\times}10^{14}$ to $1{\time}10^{16}ions\;cm^{-2}$. The Cu layers were then deposited on the implanted PI. The surface properties of the implanted PI film were investigated based on the contact angle measurements, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Furthermore, the adhesive strength between the deposited Cu layer and PI film was estimated through a scratch test using a nanoindenter. As a result, the surface environment of the PI film was changed by the ion implantation, which could have a significant effect on the adhesion between the deposited Cu layer and the PI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1059-1065
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• 1998

It is very crucial to make the phase holograms have the exact phase difference in the fabrication process. We have developed a fabrication criterion of obtaining the exact phase difference of the holograms by using the relation between the zeroth order intensity of diffected beam and the relative phsse difference of the fabricaated holograms. We have fabricated holograms having phaes of .pi. and .pi./2, respectively, and we could get multi-phase holograms by combining these two binary thase holograms.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.29-39
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• 1999

Both conventional and PI3 implanters require dense sources for high productivity rate, and small sheath expansion in PI3 besides. The problem of the creation of large volume uniform plasma in PI3 facilities replaces that of beam forming in accelerators. Some aspects of ion extraction in both cases and Langmuir probe plasma diagnostics with be discussed. Plasma parameters of large volume multicusp dc hot cathode and inductively coupled RF plasma sources obtained with Langmuir probe and ion mass analyzer with be presented. Design features and performances of high current Freeman and ECR ion sources will be described.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.6-6
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• 1992

Ionized cluster beam deposition (ICBD) technique has been employed to fabricate high-purity crystalline polyimide (PI) film. The pyromellitic dianhydride (PMDA) and oxydianiline (ODA) were deposited using dual ICB sources, Fourier trans forminfraredspectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS), and Transmission electron microscopy (TEM)study show that the bulk and surface chemical properties and the crystalline structure are very sensitive to the ICBD conditions such as cluster ion acceleration voltage and ionization voltage, At optimum ICBD conditions, the PI films have a maximum imidization, negligible impurities(∼1% isoimide), and a good crystalline structure probably due to the high surface migration energy and surface cleaning effect. These characteristics are superior to those of films deposited by other techniques such as colvent cast, vapowr deposition, or sputtering techniques.

• Journal of the korean Society of Automotive Engineers
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• v.3 no.1
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• pp.54-60
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• 1981

This paper presents the dynamic behaviour of a simple beam subjected to moving loads and prebending moments. The velocity of the moving loads is assumed constant, and the prebending moment is assumed to be M. The fundamental equation of motion of the beam is derived from the principle of virtual works and solved by using Duhamel's Integral. In this paper we found that the dimensionless deflection at the middle of beam was related with prebending moment(M), velocity(V) and magnitude of the moving load(F) ; that is y/y$_{0}$=1/1-.betha.$^{2}$-.pi.M/Fl The faster the velocity becomes, the deeper the maximum deflection becomes. And the maximum deflection at the middle of beam was occurred after the moving load passed the midpoint of beam.

• Computers and Concrete
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• v.1 no.2
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• pp.115-130
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• 2004

The flexural ductility of solid rectangular reinforced concrete beams has been studied quite extensively. However, many reinforced concrete beams are neither solid nor rectangular; examples include T-, ${\Gamma}$-, ${\Pi}$- and box-shaped beams. There have been few studies on the flexural ductility of non-rectangular reinforced concrete beams and as a result little is known about the possible effect of sectional shape on flexural ductility. Herein, the effect of sectional shape on the post-peak flexural behaviour of reinforced normal and high-strength concrete beams has been studied using a newly developed analysis method that employs the actual stress-strain curves of the constitutive materials and takes into account the stress-path dependence of the stress-strain curve of the steel reinforcement. It was revealed that the sectional shape could have significant effect on the flexural ductility of a concrete beam and that the flexural ductility of a T-, ${\Gamma}$-, ${\Pi}$- or box-shaped beam is generally lower than that of a solid rectangular beam with the same overall dimensions and the same amount of reinforcement provided. Based on the numerical results obtained, a simple method of ensuring the provision of a certain minimum level of flexural ductility to non-rectangular concrete beams has been developed.