• Journal of Information Display
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• v.2 no.3
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• pp.6-12
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• 2001

Formation of intensity gratings was studied with two s-polarized (s+s) configuration in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane, T-AB; cyanobiphenyl, CB-AB) by photoinduced alignment of PLCs. Remarkable differences were observed between the two PLCs. T-AB showed a faster response to the change in the diffraction intensity than CB-AB. In T-AB, alignment change took place faster than that of CB-AB. By introducing the tolane unit at the side chain, we obtained a diffraction efficiency of 30 % in the Raman-Nath regime

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.27-27
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• 2003

The Automated Quantitative Knife-Edge Test (AQuaKET) method was developed for testing the surface profiles of large optics with high accuracy. Testing with the required accuracy of very large telescope is not an easy job to achieve, as it is a nano-technology. There are lots of possible error sources which can occur during the measurements and in the data processing of the AQuaKET. The error sources can be categorized into 5 areas: optics, mechanics, electronics, numerical processes, and system. In this paper, possible error sources in Optics are discussed, which are intensity variation of the light source, diffraction effects, and parallax effect. In this talk, those possible error sources in optics are presented and discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.137-140
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• 2001

To improve structural properties and induce higher conductivity, we have annealed emitting layer. The temperature condition was investigated by various experiment. To observe the surface morphology of emitting layer, measured the AFM and the X -ray diffraction pattern of P3HT film is shown. It is move to slightly low angles and diffraction peaks also become much sharper. After annealing of emitting layer, EL intensity and Voltage-current-luminance curve is better as compared with untreated. But PL intensity was decreased. It is known that by emission principal. After annealing of emitting layer, EL devices enhances the interface adhesion between the emissive polymer and Indium-tin-oxide electrode, which takes a critical role to improve the emitting properties of EL devices.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.171-180
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• 1993

X-ray photoelectron diffraction (XPD) is used to characterize the crystallographically cleaved GaAs(110) surface. By using polar and azimuthal scans of the usual angle-resolved x-ray photoelectron spectroscopy, we get the reconstruction geometry of the clean GaAs(110) surface from the intensity ratio of Ga 3d core-level peaks. The reconstruction parameters are determined by fitting the diffraction pattern with the single scattering cluster (SSC) model, and the results show similar tendencies to those obtained by other techniques.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.496-502
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• 2001

We generated a nondiffracting beam and investigated its intensity profile on propagation. We first obtained an annular output beam from Nd:YAG laser with a negative branch unstable ring resonator and, using a 1m focal length lens, we generated a Bessel- Gauss beam. The inner radius of the annular output beam was 2.57 mm and the ring width was 0.145 mm. The intensity profile of the nondiffracting beam did not show any appreciable diffraction up to 33 m distance from the focal lens. This result was compared with the theory.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.75-80
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• 2001

Holographic polymer dispersed liquid crystals (HPDLCs) have fabricated by irradiating an Ar-ion laser ( ${\lambda}$=514nm) at various intensity on LC/acrylate monomer mixtures which were sandwitched between two ITO coated glass plates. Monomer systems were composed of dipentaerythritol-hydroxy penta acrylate (DPHPA, f=5)/monofunctional acrylate monofunctional monomers. The LC used in this system was E7 (BL001, Merck). Gratings were fabricated by periodic interference of twobeams. Reflection efficiency-irradiation intensity-monomer type relationships were obtained from the UV-visible spectra of the HPDLC films. Peaks were found at a bit smaller wavelength than 514nm, due to the shrinkage of mixture volume upon polymerization. Real time measurements of diffraction efficiency have been obtained according to monomer types and LC contents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.137-140
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• 2001

To improve structural properties and induce higher conductivity, we have annealed emitting layer, The temperature condition was investigated by various experiment. To observe the surface morphology of emitting layer, measured the AFM and the X-ray diffraction pattern of P3HT film is shown. It is move to slightly low angles and diffraction peaks also become much sharper. After annealing of emitting layer, EL intensity and Voltage-current-luminance curve is better as compared with untreated. But PL intensity was decreased. It is known that by emission principal. After annealing of emitting layer, EL devices enhances the interface adhesion between the emissive polymer and Indium-tin-oxide electrode, which takes a critical role to improve the emitting properties of EL devices.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.73-75
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• 2005

The objective of this study is to estimate the feasibility of X-ray diffraction method application for fatigue life assessment of the high-temperature pipeline steel such as main steam pipe, reheater pipe and header etc. in power plant. In this study, X-ray diffraction tests using various types of specimen simulated low cycle fatigue damage were performed in order to analyze fatigue properties when fatigue damage conditions become various stages such as 1/4, 1/2 and 3/4 of fatigue life, respectively. As a result of X-ray diffraction tests for specimens simulated fatigue damages, we conformed that the variation of the full width at half maximum intensity decreased in proportion to the increase of fatigue life ratio.

• Applied Microscopy
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• v.41 no.1
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• pp.75-79
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• 2011

For quantitative analysis of nano-crystal structure, we reported the accuracy improvement method of lattice parameters measured from electron diffraction. For calculation of Au lattice parameters used as a standard crystal structure, it was considered two different acquisition methods (detector and enegy-filter) and three different calculation methods (conventional, least-square and regression fit). As a result, the measurement reliability could be enhanced by using CCD camera which gives higher performance, while energy-filtering did not affect the improvement the camera constant accuracy. Also, the accuracy of lattice parameters could be improved up to $10^{-4}$ order by regression fitting with correction formula. Finally, it is expected that the combination of regression fitting and intensity extraction from energy-filtered precession electron diffraction gives a solution of quantitative structure analysis for unknown nano-crystals.

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.1-6
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• 1991

This paper describes the theoretical analysis of a diffraction pattern analyzer for the characterization of microscale object fields and a method for obtaining size and size distribution from the measured diffraction pattern of the object fields. For the experimental verification, a typical optical Fourier transform system was set up and calibrated with 2 5$\mu \textrm m$ and 50$\mu \textrm m$ pinholes. The system responses to distilled water droplets, alcohol, glycerin and silicon oil were imaged with vidicon, and the image was processed to determine the size distribution of each liquid particle field. The energy distribution function which is defined as the total intensity of a circular ring in the diffraction pattern was used to determine the dominant particle size of each liquid particle field.