• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.307-308
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• 2007

We present a novel chromatic dispersion measurement method using a spectral domain interferometer for single mode optical fiber over a wide spectral range (200 nm). This technique is based on the Mach-Zehnder interferometer using a white light source and spectrometer. A phase was directly retrieved from a measured spectral interferogram to obtain relative group velocity, chromatic dispersion and dispersion slope. The measured results with the proposed method were compared with those obtained using a conventional measurement method. Those results have good agreement with each other. Our proposed method can simply, accurately, and quickly (< 500 ms) measure chromatic information for a short length of optical fiber as well as optical device.

• Current Optics and Photonics
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• v.4 no.4
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• pp.336-344
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• 2020

Exact optical characterization of virtual and augmented reality devices using conventional luminance measuring methods is a time-consuming process. A new measurement method is proposed to estimate in a relatively short time the boundary of ray trajectories emitting from a specific position on a virtual images. It is assumed that the virtual image can be modeled to be formed in front of one's eyes and seen through some optical aperture (field stop) that limits the field of view. Circular and rectangular shaped virtual images were investigated. From the estimated ray boundary, optical characteristics, such as the viewing direction and three dimensional range inside which a eye can observe the specified positions of the virtual image, were derived. The proposed method can provide useful data for avoiding the unnecessary measurements required for the previously reported method. Therefore, this method can be complementary to the previously reported method for reducing the whole measurement time of optical characteristics.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.115-120
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• 2005

As a popularity of a portable digital device such as a cellular phone, a digital camera and a MP3 player is spreading, the demand of the mobile storage device increases rapidly. A bluray technology using 405nm laser diode and objective lens having high NA(Numerical Aperture), 0.85, satisfies a miniaturization and a high capacity which are the requirements of the portable device. To develop SFFOP(small form factor optical pickup), it is prerequisite to minimize the number of optical components and establish evaluation and assembly method of micro optical pickup system as well as mass production method of micro optical component. To minimize optical elements of optical pickup, there have been many researches to use P-HOE(Polarized Holographic Optical Element) due to its extremely small size and versatile function. However, P-HOE is handled and assembled very accurately in SFFOP. In this paper, static error signal detection method is developed for an alignment of P-HOE in SFFOP. Using developed static error signal detection method, P-HOE can be aligned very accurately with real time result of static error signals of pickup such as FES(focusing error signal) and TES(Tracking Error Signal). The developed static error signal detection method is verified by the evaluation of commercialized DVD Pickup. And finally. developed static error signal detection method is applied for the assembly of P-HOE in SFFOP system satisfies specification of BD(Blu-ray Disk).

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.262-270
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• 2013

In this paper, we propose a modified optical CBC(Cipher Block Chaining) encryption method using optical XOR logic operations. The proposed method is optically implemented by using dual encoding and a free-space interconnected optical logic gate technique in order to process XOR operations in parallel. Also, we suggest a CBC encryption/decryption optical module which can be fabricated with simple optical architecture. The proposed method makes it possible to encrypt and decrypt vast two-dimensional data very quickly due to the fast optical parallel processing property, and provides more security strength than the conventional electronic CBC algorithm because of the longer security key with the two-dimensional array. Computer simulations show that the proposed method is very effective in CBC encryption processing and can be applied to even ECB(Electronic Code Book) mode and CFB(Cipher Feedback Block) mode.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.162-163
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• 1999

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.12-15
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• 1996

The purpose of image sequence coding is to reduce the spatio-temporal redundancies. The transform coding such as DCT is used for the spatial redundancies. In this paper, the optical flow method is applied to solve the problem of temporal redundancies. So far, pixel intensity conservation has been used to solve the optical flow. We used the neighborhood information as well as pixel intensity conservation. And we compared the merits and demerits of the conventional method and the proposed method in this paper.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.300-301
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• 2003

As the demand for high frequency(bandwidth) optical module is increased, there is a need for fabricating silicon optical bench(SiOB) with low parasitic impedance. In this paper, we discuss multi-layer structure method for manufacturing SiOB with low capacitance. This structure method decreases the capacitance between the conductive patterns for about 94∼97％ compared to the conventional structure without raising the resistivity of silicon, or increasing the thickness of the dielectric film.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.66-67
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• 2001

We explain a method to obtain optical Hough transform filters by use of multiplexed holograms and how they are used for optical pattern recognition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.135-140
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• 2003

The convergence of finite volume method (FVM) or discrete ordinate method (DOM) is known to degrade for optical thickness greater than unity and large scattering albedo. The present article presents a convergence acceleration procedure for the FVM based on a full approximation storage (FAS) multigrid method. Among a variety of multigrid cycles, the V-cycle is used and the full multigrid algorithm (FMG) is applied to an analysis of radiation in irregular two-dimensional geometry. Solution convergence is discussed for the several cases of various optical thickness and scattering albedo. At small scattering albedo and optical thickness, there is no advantage to using the multigrid method for calculation CPU time. For large scattering albedo greater than 0.5 and optical thickness greater than unity, however, the multigrid method improves the convergence and the solution is rapidly obtained.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.3
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• pp.162-168
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• 2006

Speckle interferometry with phase-shifting method has been applied to measurement of micro-scale displacement through optical signal processing. Four-step phase-shifting method by PZT is used to measure out-of-plane displacement in spot-welded cantilever and results of optical experiments are comparable to those of FEM. Phase-shifting method using Fourier transform by PZT is applied to measurement of in-plane displacement on rectangular steel plate with a circular hole. The results of optical experiment agree well with theoretical calculation. New phase-shifting method in speckle interferometry has been implemented with a quarter wave plate. In-plane displacement of specimen is measured by the new phase-shifting method. Results of optical experiment show that the quarter wave plate can be used for phase-shifting method that is cheap and easy to use in speckle interferometry.