• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.12
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• pp.22-27
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• 2015

Conoscopic holography, which consists of two linear polarizers and two wave plates, and an uniaxial crystal, is incoherent holographic technology for three-dimensional display. In the uniaxial crystal, the wave from object divides into extraordinary and ordinary waves and phase difference between two waves is caused by the different refractive index of two waves. Four intensity patterns, which are made by phase difference, are obtained using LCLV(liquid crystal light valve) and conoscopic holography system. By combining four intensity patterns, the complex hologram without bias and conjugate image. In this paper, we propose the optimized system, which consists of a wave plate and a linear polarizer, and uniaxial crystal. In the proposed system, it doesn't need LCLV. By adjusting the azimuth angle of a linear polarizer and a wave plate, we derive four intensity patterns in recording plane. We demonstrate theoretically that the complex hologram with bias and a conjugate image is obtained using the proposed system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.306-317
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• 1995

Abstract Gallium arsenide crystal is usually grown from the melt by the horizontal Bridgman method. We constructed pseudo - steady - state model for crystal growth of GaAs which inclue melt, crystal and the free interface. Mathematical equations of the model were solved for flow, temperature, and concentration field in the melt and temperature field in the crystal. The location and shape of the interface were also solved simultaneously. In 2 - dimensional model, the shape of the interface is flat with adiabatic thermal boundary condition, but it becomes curved with completely conducting thermal boundary condition. In 3 - dimensional model, the interface is less curved than 2 - dimensional case and the flow intensity is similar to that of 2 - dimensional case. With the increase of flow intensity vertical segregation shows maximum value in both 2 - and 3 - D model. However, the maximum value occurs in lower flow intensity in 2 - D model because the interface is more curved for the same flow intensity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.207-210
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• 2001

Metal-organic VPE (MOVPE) epitaxial growth procedure and related device fabrication technique are reported for GaInP-based epitaxial materials and devices. For GaInP/GaInAs two-dimensional electron-gas field-effect transistor (TEGFET), a promising epitaxial stacking structure resulting in enhanced electron mobility is given. In conjunction with this, a new device fabrication technique to improve luminous intensity of GaInP-based LED is also shown.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.753-760
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• 1999

Experiments were conducted to investigate the effect of the initial turbulent intensity on the flow and heat transfer characteristics for a two-dimensional impinging jet. A square rod was installed at the nozzle exit to increase initial turbulent intensity. A hot wire probe and thermochromic liquid crystal technique were used to measure the turbulent intensity and the surface temperature. All measurements were made over a range of nozzle-to-plate distance from 1 to 10 at Re=20,000. When the rod is not installed, the maximum stagnation point Nusselt number is occurred at H/B=9. A higher initial turbulent intensity enhanced the heat transfer on the surface. A correlation between stagnation point Nusselt number and turbulent intensity are presented.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.41-46
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• 1992

Mutually pumped phase conjugator(MPPC) is experimentally investigated and analyzed in terms of fanning gratings of a photorefractive BaTiO$_3$ crystal. As considering the intensity-dependent absorption and coupling cofficients in photorefractive two wave mixing, the dependence of phase conjugate reflectivites on the incident angle, beam ratio, and total intensity in MPPC is analyzed.

• Korean Journal of Crystallography
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• v.14 no.1
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• pp.24-24
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• 2003

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.581-586
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• 1998

We investigated the effect of mechanical back side damage in Czochralski grown silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductivity decay method, degree of X-ray diffuse scattering, X-ray section topography, and wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the magnitude of diffuse scattering and X-ray excess intensity increased proportionally, and it was at Grade 1:Grade 2:Grade 3=1:7:18.4 that the normalized relative quantization ratio of excess intensity in damaged wafer was calculated, which are normalized to the excess intensity from sample Grade 1.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.389-393
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• 2000

High-quality $Er^{3+}$ doped Mg : $LiNbO_3$single crystal fibers were grown by a micro-pulling down ($\mu$-PD) method. Single crystal fibers were pulled down through the nozzle, at a pulling down rate of 0.5 mm/min and using a Pt crucible with a nozzle 1 mm in diameter in air atmosphere. Defects such as bubbles, cracks and inclusions were not detected in any of the grown crystals. The optical transmission of Er : Mg : $LiNbO_3$crystal was measured and the energy levels of $Er_2O_3$ ion could be calculated. The photoluminescence spectrum of crystal fibers showed an energy band emission with the strongest line corresponding to the $^4I_{3/2}{\to}^4I_{15/2}$transition. The concentration dependence of the entire wavelength region emission intensity upon excitation intensity measured emission intensity for the 3 mol% MgO doped fibers was larger than that for the 1, 5 mol% MgO doped fibers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.80-85
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• 2000

The rheology of alumina slurries with maltodextrin was studied with different processing routes using experimental design and statistical analysis. Different processing routes include maltodextrin addition, different ultrasonication intensity applied to the slurries before or after adding maltodextrin, and shaking time. Viscosities of the slurries showed shear thinning behavior and were correlated with the Ostwald-de-Weale model. The viscosities of alumina slurries decreased with the addition of maltodextrin and increased with ultrasonication intensity. There were little differences in the viscosities of the slurries depending on whether maltodextrin was added before or after ultrasonication.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.408-413
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• 1995

We investigated the effect of mechanical backside damage upon minority carrier recombination lifetime measurement in Czochralski silicon substrate by laser excitation/microwave reflection photoconductance decay method. The intensity of mechanical damage was evaluated by X-ray double crystal rocking curve, X-ray section topography and wet oxidation/preferential etch methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the threshold full width at half maximum value which affect minority carrier lifetime measurement is about 13 secs.