• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.73-83
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• 1993

The temporal differential equation describing the build-up of the space-charge field in the presence of square and sinusoidal alternating field in photorefractive materials is solved analytically. We also measured the average two-wave mixing gain and the full temopral gain variations in a B$i_{12}$Si$O_{20}$ crystal with applied fields of up to 7 KV/cm amplitude and 1 KHz repetition rate. It has been found that the experimental measurements agree well with the theoretical results.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.90-93
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• 1987

Phase conjugate wavefront generation via real-time holography in degenerate four-wave mixing experiments in photo-refractive crystal $Bi_{12}$ Si $O_{20}$ is presented. Depending on the respective values of applied field $E_o$ and fringe spacing, drift or diffusion of the photecarriers dominates the space-charge buildup and affects the Phasa- Conjugate Wavefront intensity. The experimental results for wavefront reflectivity as a function of the intensity ratio of the writing beams agree with the theoretical predictions.

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.133-138
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• 1991

Eosin-doped boric acid glass saturable absorber has a relatively low saturation intensity (700 mW/$\textrm{cm}^2$) and low power optical phase conjugation is achived by the degenerate four-wave mixing (DFWM) experiments. Polarization properties of optical phase conjugation by DFWM have been demonstrated in this materials using a cw argon ion laser at wavelength 488 nm. The dependence of the phase conjugated reflectivity on the intensity and wavelength of the pump beam is examined. The magnitude of the energy exchange by the nondegenerate two-wave mixing (NDTWM) is maximized by frequency difference between the two beams of $\varphi\simeq$ 1100 Hz.

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.188-191
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• 2004

A new laser Doppler velocimeter employing a $CO_2$ laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as small as 50 kHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

• International Journal of Aerospace System Engineering
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• v.3 no.1
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• pp.30-38
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• 2016

The The turbulent mixing characteristics of Kerosene-LOx in a coaxial swirl injector 100 bar have been numerically investigated. Turbulent model is based on large eddy simulation with real-fluid transport and thermodynamics. The effects of equation of state (EOS), chamber pressure are evaluated in a point of the mixing efficiency and pressure fluctuations. The dominant frequency is same as the hairpin vortex shedding frequency generated by film wave at the LOx post.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.421-422
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.192-193
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• 2004

• Proceedings of the KIEE Conference
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• 1976.08a
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• pp.49-52
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• 1976

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.42-43
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• 2004

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.83-86
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• 2002

We suggest binary image decryption system using two-wavc mixing in Photorefractive crystal. Compared with a conventional method, this method can make optical alignment easily, and brighten the encrypted image even if a small input signal, by index grating of photorefractive crystal. Also it can reconstruct the encrypted image by only reference beam in real time.