• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.79-82
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• 2015

The handicap for investigating the aero-optical effect focuses on the accurate prediction on the index refraction fluctuation or density fluctuation. In recent years, with the development of CFD techniques and optical experimental techniques, the comprehension have developed on the aero-optical transmitting effect in many kinds of complex flow. This study mainly introduces the optical aberration in compressible mixing layer. And then the debates about the mechanism of aero-optical effects and assessment of image blur also present.

• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.73-79
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• 1997

We analyzed the variation of the focus error signal with the effect of land and groove, wavefront error, and optical system parameter variation for the knife-edge and astigmatism methods on the Land/Groove recordable optical disc, using a numerical simulation method. We verified causes of the zero-cross-shift that took place by the effect of land and groove by analyzing the diffraction beam including defocus wavefront errors. We also found that the sensitivty of the focus error signal was reduced by the effect of land and groove in the astigmatism method, as in the analysis of the focus error signal with the each order of the diffraction beam.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.677-683
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• 2002

The analytical and experimental studies on aerodynamic flutter instability of rotating disks in information storage devices are investigated. The theoretical analysis uses a fluid-structure model where the aerodynamic force on the rotating disk is represented in terms of lift and damping forces. Based on the analytical approach, it is shown that the backward natural frequency of the disk is equal to that of the case without aerodynamic effect at the flutter onset speed. In post-flutter regions, the natural frequencies are larger than those in vacuum conditions without aerodynamic effect. The analytical predictions on the natural frequencies of rotating disks with/without aerodynamic effect are experimentally verified using a vacuum chamber and ASMO optical disks.