• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.110-111
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• 2002

Controllable waveguide of optical vortex solitons is possible by using the rotational characteristics of optical vortices, while the relative phase difference across the soliton profiles can be used to steer the waveguide direction in case of two-dimensional dark solitons. It is important to understand in detail what sources contribute to the rotation of optical vortices to apply optical vortex solitons to the optical switchyard. (omitted)

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.124-125
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• 2000

Since Nye and Berry$^{(1)}$ showed that in free space the electromagnetic field could contain stable, propagating phase singularities termed "dislocations", optical dislocations have been extensively investigated in nonlinear optics and laser physics. As the wave propagates, the lines of constant phase surrounding a dislocation trace out a spiral in space or in time. So these phase singularities are now usually referred to as optical vortices. Baranova and her co-workers$^{(2)}$ have shown that in fully developed speckle patterns, there is, one optical vortex accompanying each speckle spot on average. Among these vortices there are networks in phasemap because only one phase is to be assigned in one point except optical dislocations having zero amplitude. Freund et al.$^{(3)}$ have been studied optical dislocation networks and simulations are compared with experimental results. (omitted)

• Current Optics and Photonics
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• v.1 no.4
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• pp.396-401
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• 2017

In this article, we proposed hybrid polarization singularity configurations, based on the superposition of two orthogonal circularly polarized components, one of which is a light beam with two optical vortices. The topological configurations are the hybridization of lowest-order polarization singularities, but are different from high-order polarization singularities. Our numerical simulation may provide a theoretical basis for expanding the variety of polarization singularity configuration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.91-94
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• 2003

An experimental study has been carried out in a supersonic blow-down wind tunnel for examining the influence of streamwise vortices on normal shock-wave/boundary layer interaction. It has been reported by the earlier investigator the streamwise vortices generated by the blowing jets can significantly suppress the shock-induced separation and reduce the wave drag. The blowing jets generate the streamwise vortices with 45$^{\circ}$ angle in the spanwise direction. The shock waves are visualized by a Schlieren optical system. Appropriate measurement systems are provided for the characterization of shock wave/boundary layer interaction. The chamber pressure ratio and blowing pressure ratio are varied from 1.5 to 2.4 and 1.0 to 2.0 respectively.

• Membrane Journal
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• v.2 no.2
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• pp.104-111
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• 1992

A curved channel duct is designed, built and used specifically to produce Dean vortices as a result of flow around a $180^{\circ}C$ curve. We present evidence using optical reflection of the existmace of the vortices in the curved section and following flat section. Also, three different feed soludons(DI water, a monodispersed styrene-divinyl-benzene latex particle suspension and a yeast suspension) were used to determine the effectiveness of Dean instabilities to destabilize polarization layers. For each suspension, the flux data were compared as a function of time for flow conditions with and without Dean vortices, for a $0.2{\mu}m$ microfiltration membrane. Any permeation flux improvement was not sustained for $2.0De_c$ due to the vortex-decay in the flat section after the curved channel, but a 15~30% permeation improvement was obtained for $3.8De_c$.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.130-131
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.160-161
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• 2003

위상특이점이라고도 불리는 광 보텍스(optical vortex)를 포함한 빔은 파면의 특이성 때문에 많은 관심을 끌어왔다. 위상을 정의할 수 없는 위상특이점을 따라서는 빔의 동일위상파면이 소용돌이 형태를 가진다. 그 소용돌이 정도는 위상전하(topological charge) 라는 양으로 특징지을 수 있다. 광 보텍스는 선형 및 비선형적 특성에 대해 많은 연구가 이루어져왔다. 레이저 공진기를 변형하거나, 홀로그램이나 위상마스크에 레이저를 조사하여 보텍스를 발생시키는 방법 등의 여러 방법이 알려져 있다. (중략)

• Current Optics and Photonics
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• v.1 no.6
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• pp.631-636
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• 2017

We firstly develop a straightforward method to generate full $Poincar{\acute{e}}$ beams with any polarization geometry over an arbitrary order $Poincar{\acute{e}}$ sphere. We implement this by coaxial superposition of two orthogonal circular polarized beams with alternative topological charges with the help of a Mach-Zehnder interferometer. Secondly we find the existence of singularity points. And the inner relationship between their characteristics and the order of $Poincar{\acute{e}}$ spheres is also studied. In summary, this work provides a convenient and effective way to generate vector beams and to control their polarization states.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.179-184
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• 2001

A shrouded rotating disk airflow has a simple figure on geometric basis, but has various and complicated forms of flow. This flow type can be applied to many turbo devices such as information storage device(optical disk). Circumferential velocity frequency in the middle plane between disk and shroud wall is measured using laser Doppler velocimeter. Solid body region of flow was founded when low Reynolds number relatively. Through the informations of the experimental results. we could examine the number and distribution of the vortices. When Reynolds number $3.80{\times}10^5$ there is a dominant frequency of which vortices number is 5.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.991-997
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• 2003

A flow field around a disc in an optical disc drive is invested using numerical methods. The high-speed rotating disc induces a strong flow field around the disc, which causes the pressure distribution on the surfaces of the disc. The pressure difference between the upper and the lower surfaces causes the deformation of the disc. In the first part of this study, flow fields around a rotating disc and a stationary wall are investigated using a similarity solution method, in order to identify the effect of the distance between the disc and the wall on the pressure distribution on the surfaces of the disc. In the second part, flow field in a slim-type optical disc drive is studied using a commercial code in order to consider the effect of the vortices generated by the local geometry of the drive.