• Journal of Magnetics
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• v.11 no.4
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• pp.195-207
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• 2006

The recently published and new results on design and fabrication of magnetophotonic crystals of different dimensionality are surveyed. Coupling of polarized light to 3D photonic crystals based on synthetic opals was studied in the case of low dielectric contrast. Transmissivity of opals was demonstrated to strongly depend on the propagation direction of light and its polarization. It was shown that in a vicinity of the frequency of a single Bragg resonance in a 3D photonic crystal the incident linearly polarized light excites inside the crystal the TE- and TM-eigen modes which passing through the crystal is influenced by Brags diffraction of electromagnetic field from different (hkl) sets of crystallographic planes. We also measured the faraday effect of opals immersed in a magneto-optically active liquid. It was shown that the behavior of the faraday rotation spectrum of the system of the opal sample and magneto-optically active liquid directly interrelates with transmittance anisotropy of the opal sample. The photonic band structure, transmittance and Faraday rotation of the light in three-dimensional magnetophotonic crystals of simple cubic and face centered cubic lattices formed from magneto-optically active spheres where studied by the layer Korringa-Kohn-Rostoker method. We found that a photonic band structure is most significantly altered by the magneto-optical activity of spheres for the high-symmetry directions where the degeneracies between TE and TM polarized modes for the corresponding non-magnetic photonic crystals exist. The significant enhancement of the Faraday rotation appears for these directions in the proximity of the band edges, because of the slowing down of the light. New approaches for one-dimensional magnetophotonic crystals fabrication optimized for the magneto-optical Faraday effect enhancement are proposed and realized. One-dimensional magnetophotonic crystals utilizing the second and the third photonic band gaps optimized for the Faraday effect enhancement have been successfully fabricated. Additionally, magnetophotonic crystals consist of a stack of ferrimagnetic Bi-substituted yttrium-iron garnet layers alternated with dielectric silicon oxide layers of the same optical thickness. High refractive index difference provides the strong spatial localization of the electromagnetic field with the wavelength corresponding to the long-wavelength edge of the photonic band gap.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.56-62
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• 2006

Currently, Most of the Backhual and Submarine's networks are being installed using DWDM and EDFA to deal with dramatically increasing internet traffic. In a conventional type optical system, the so-called 3R repeater, fiber non- linearity was not significant factor but it is one of the most important consideration when designing new DWDM network based on the EDFAs. To minimize the signal pulse distortion in long-haul optical network, Zero-dispersion fiber is indispensable but causes the fiber non-linearity. Therefore this conflicting problems should be managed to transmit a high-speed capacity traffic. In this paper, key technologies in DWDM submarine optic network were found out for a high capacity traffic and introduced the dispersion management way for solving the conflicting problems between Zero-dispersion and non-linearity. Lastly designed a dispersion map in section between Korea and Hong-kong.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.46-52
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• 2011

A confocal microscope was developed utilizing a scanning sample stage based on a home-built double-compound flexure guide. A scanning sample stage with nano-scale resolution consisted of a double leaf spring based flexure, a displacement amplifying lever, a Piezo-electric Transducer(PZT) actuator and capacitance sensors. The performance of the two-axis stage was analyzed using a commercial finite element method program prior to the implementation. A single line laser was employed as the light source along with the Photo Multiplier Tube(PMT) that served as the detector. The performance of the developed confocal microscope was evaluated with a mouse ear skin imaging test. The designed scanning stage enabled us to build the confocal microscope without the two optical scanning mirror modules that are essential in the conventional laser scanning confocal microscope. The elimination of the scanning mirror modules makes the optical design of the confocal microscope simpler and more compact than the conventional system.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.79-89
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• 2023

A multi-view display is regarded as the most practical technology to provide a three-dimensional effect to a viewer because it can provide an appropriate viewpoint according to the observer's position. But, most multi-view displays with flat shapes have a disadvantage in that a viewer watches 3D images only within a limited front viewing angle. In this paper, we proposed a spherical display using a ball lens with spherical symmetry that provides perfect parallax by extending the viewing zone to 360 degrees. In the proposed system, each projection lens is designed to be packaged into a small modular array, and the module array is arranged in a spherical shape around a ball lens to provide vertical and horizontal parallax. Through the applied optical module, the image is formed in the center of the ball lens, and 3D contents are clearly imaged with the size of about 0.65 times the diameter of the ball lens when the viewer watches them within the viewing window. Therefore, the feasibility of a 360-degree full parallax display that overcomes the spherical aberration of a ball lens and provides a wide field of view is confirmed experimentally.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.283-288
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• 2004

The measurement of ultra low aspect ratio fluid film thickness is very crucial technique both for the verification of lubrication media characteristics and for the clearance design in many precision components such as MEMS, precision bearings and other slideways. Many technologies are applied to the measurement of ultra low aspect ratio fluid film thickness (i.e. elastohydrodynamic lubrication film thickness). In particular, in-situ optical interferometric method has many advantages in making the actual contact behaviors realized with the experimental apparatus. This measurement method also does the monitoring of the surface defects and fractures happening during the contact behavior, which are delicately influenced by the surface conditions such as load, velocity, lubricant media as well as surface roughness. Careful selection of incident lights greatly enhances the fringe resolutions up to $\~1.0$ nanometer scale with digital image processing technology. In this work, it is found that coaxial aligning trichromatic incident light filtering system developed by the author can provide much finer resolution of ultra low aspect ratio fluid film thickness than monochromatic or dichromatic incident lights, because it has much more spectrums of color components to be discriminated according the variations of film thickness. For the measured interferometric images of ultra low aspect ratio fluid film thickness it is shown how the film thickness is finely digitalized and measured in nanometer scale with digital image processing technology and space layer method. The developed measurement system can make it possible to visualize the contact deformations and possible fractures of contacting surface under the repeated loading condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.71-82
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• 2007

Recent advances in optical-network technologies have led to the advent of broadband networks reaching 10 Gbps. The increase of available network bandwidth envisions wide-spread use of broadband applications such as uncompressed Internet HDTV, which would be a cutting-edge application for networked collaborations. Despite of breakthroughs in high-performance systems and networks, expensiveness blocks wide-range deployments of uncompressed Internet HDTV systems. In this paper, we propose a low-cost uncompressed Internet HDTV system and discuss its software architecture in depth. We conducted several network-based experiments utilizing a research network test-bed to evaluate the performance of the proposed system.

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.159-169
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• 2017

The Satellite Electro-Optic Payload System needsspecial requirements with the conditions of limited power consumption and the space environment of solar radiation. The acquired image quality should be mainly depend on the GSD (Ground Sampled Distance), SNR (Signal to Noise Ratio), and MTF (Modulation Transfer Function). On the well-manufactured sensor level, the thermal noise is removed on ASP (Analog Signal Processing) using the CDS (Corrective Double Sampling); the noise signal from the image sensor can be reduced from the offset signals based on the pre-pixels and the dark-pixels. The non-uniformity shall be corrected with gain, offset, and correction parameter of the image sensor pixel characteristic on the sensor control system. This paper describes the SNR enhancement method of the satellite EOS payload using the mentioned noise remove processes on the system design and operation, which is verified by tests and simulations.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.95-102
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• 2008

An advantage of parallax barrier displays is that they can also display 2D and 3D contents and can be automatically switched between the two types. But, as the viewer changes position, different views of the scene will be directed by the barrier to the visual system. Moving horizontally beyond a certain point will produce "image flipping" of the different views of the scene. These limitations make unavoidable the use of another autostereoscopic display solutions like eye tracking or increasing the number of views. In this paper, a method of the moving parallax barrier design is introduced to supplement a disadvantage of the fixed parallax barrier that provides observation at specific locations. For making the moving parallax barrier, the cross connector with 640 lines FPC is designed. A commercially available web camera is utilized to implement eye-tracking system and shows the experimental result.

• Korean Journal of Optics and Photonics
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• v.27 no.5
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• pp.165-173
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• 2016

In this paper, we propose a three-dimensional (3D) scanning system based on two line lasers. This system uses two line lasers with different wavelengths as light sources. 532-nm and 630-nm line lasers can compensate for missing scan data generated by geometrical occlusion. It also can classify two laser planes by using the red and green channels. For automatic registration of scanning data, we control a stepping motor and divide the motor's rotational degree of freedom into micro-steps. To this end, we design a control printed circuit board for the laser and stepping motor, and use an image processing board. To compute a 3D point cloud, we obtain 200 and 400 images with laser lines and segment lines on the images at different degrees of rotation. The segmented lines are thinned for one-to-one matching of an image pixel with a 3D point.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.423-428
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• 2004

The development of a compact and high performance MWIR thermal imaging sensor based on the SOFRADIR 320${\times}$240 element IRCCD detector is described. The sensor has 20 magnification zoom optics with the maximum 40$^{\circ}$${\times}$30$^{\circ}$ of super wide field of view and 7.6 cycles/mrad of resolving power with the operation of attached micro-scanning system. In order to correct nonuniformities of detector arrays, we have proposed a multi-point correction method using defocusing of the optics and we have acquired the highest quality images. The MRTD of our system shows good results below 0.05K at spatial frequency 1 cycles/mrad at narrow field of view. Experimental data and obtained performances are presented and discussed.