• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.108-111
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• 2000

We will illustrate the topographical structure and optical structure of the merocyanine dye LB films obtained by the scanning near-field optical/atomic force microscopy (SNOAM). SNOAM was recognized as a powerful tool to modify the surface as well as to characterize the topography of the surface at atomic resolution, especially for optical reaction materials. SNOAM images showed that the topographical and optical structures of these films were not only depended on the chemical property but also physical property. In the continuous measurement on these dyes, the appearance of near-field optical transmission images showed a certain dependence on the kinds of dyes and the mutual mixing ratios of dyes. These experimental results suggest that there is a certain kind of interaction between these two dyes.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.4
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• pp.696-700
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• 1987

Guide modes in a graded index multinmode optical fiber are turned into clad modes when the optical fiber was bended into a perpendicular direction to its optical axes by microbending forces, which causes the loss of the guiding optical power. The theories reported on this microbending power loss can be applied to calculation of the transmission power loss only when the beding period equals to the mode coupling length. In this paper, we obtained the general expression of the optical power transmission loss in a graded index multimode fiber bended periodically. This can be applied to the calculation of the power loss of the periodically microbended fiber with an arbitrary bending shape and period. Also, by using the beam theory in mechanics, we could derive the expression of the displacement of the optical fiber caused by the external force which bends the fiber into a periodic trapezoidal shape. Experiments were carried out to determine the dependence of the power loss on the period of the microbending forces. Experimnetal results were in good agreement (in the same order of the magnitude) with theoritical values derived in our work within the bending period region of 2mm-10mm.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.99-104
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• 2006

We introduce a novel contrast mechanism for imaging superparamagnetic iron oxide (SPIO) nanoparticles (average diameter ${\sim}100nm$) using magneto-motive optical Doppler tomography (MM-ODT), which combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect the nanoparticles flowing through a glass capillary tube. A solenoid cone-shaped ferrite core extensively increased the magnetic field strength ($B_{max}=1\;T,\;{\Delta}|B|^2=220T^2/m$) at the tip of the core and also focused the magnetic force on targeted samples. Nanoparticle contrast was demonstrated in a capillary tube filled with the SPIO solution by imaging the Doppler frequency shift which was observed independent of the flow rate and direction. Results suggest that MM-ODT may be a promising technique to enhance SPIO nanoparticle contrast for imaging fluid flow.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.468-472
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• 2005

This paper is to investigate the influence of the endface quality on the loss characteristics of a plastic optical fiber connector for in-car network service. Using the parameters of the surface roughness and applied load, insertion loss of connector is measured. Due to scattering and change of refractive index, an optimal condition for low-loss coupling exists. We present the optimal condition as surface roughness $R_{rms}$ = 8 nm and contact load up to 50 N.

• Journal of the Optical Society of Korea
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• v.16 no.1
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• pp.80-84
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• 2012

A high reflectance mirror, which has very low absorption and scattering loss, was coated onto a crystalline substrate by ion beam sputtering and then annealed at $450^{\circ}C$. We carefully selected the mirror coating material, and designed the high reflectance mirror, in order to avoid UV degradation which comes from the He-Ne plasma. We measured the surface roughness of the Zerodur substrate using phase shift interferometry and atomic force microscopy, and compared it with the TIS scattering of the mirror. The cavity ring-down method was used to measure the absorption of the mirror, and the thin film structure was correlated to its results. We also compared the optical properties of coated mirrors before and after annealing.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.6
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• pp.375-382
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• 2016

This paper realizes control of the motion of a swimming robot fish in order to implement an underwater robot fish aquarium. And it implements positional control of a two-axis trajectory path of the robot fish in the aquarium. The performance of the robot was verified though certified field tests. It provided excellent performance in driving force, durability, and water resistance in experimental results. It can control robot motion, that is, it recognizes an object by using an optical flow object-detecting algorithm, which uses a video camera rather than image-detecting sensors inside the robot fish. It is possible to find the robot's position and control the motion of the robot fish using a radio frequency (RF) modem controlled via personal computer. This paper proposes realization of robot fish motion-tracking control using the optical flow object-detecting algorithm. It was verified via performance tests of lead-lag action control of robot fish in the aquarium.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.624-631
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• 2005

A note-book PC has become thinner in recent years, which requires the optical disc drives with small height and high memory capacity. Therefore the actuator of optical disc drives must be thinner and have disc tilt compensation function for high density memory. In this paper, the actuator with hybrid type is investigated for 3-axis ultra-slim actuator. A 3-axis ultra-slim actuator is designed by using the modal analysis of the actuator and the electromagnetic analysis of magnetic circuit to achieve dynamic characteristics. Also, magnetic force between tilt magnet and tilt yoke is investigated to and the influence on the DC sensitivity in the focus and track directions.

• Journal of KSNVE
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• v.10 no.4
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• pp.584-595
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• 2000

We design a new actuator for high density optical device in order to control the radial tilting motion. The newly designed actuator makes it possible to control the tilting motion actively, while the coventional actuator compress tilting motion with passive spring. First of all, We present 3-dimensional modeling of actuator and accomplish the modal analysis and magnetic analysis of actuator. Due to these results, a new designed actuator has performance of high sensitivity and high second resonance frequency. Secondly, We present the 3-DOF dynamic modeling of the 4-wire spring type actuator. sensitivity analysis is performed to consider the assembling error, such as the difference of mass center and force center. From these results, the sensitivities of rotation due to the assembly error are revealed and design criteria of rotation is presented. And experimental results of a newly designed actuator are presented and compared with theoretical results. Finally, We propose a dynamic tilt compensation and high acceleration actuator for high density optical storage devices.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.208-213
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• 2003

A note-book PC has become thinner in recent years. And optical disc drives are required to have high memory capacity. Therefore, the actuator of optical disc drives must be thinner and have disc tilt compensation function for high density memory. In this paper, the hybrid type actuator is investigated for 3-axis ultra-slim actuator. A 3-axis ultra-slim actuator is designed by using the modal analysis of the actuator and the electromagnetic analysis of magnetic circuit to achieve dynamic characteristics and magnetic flux density for high sensitivity, respectively. Also, magnetic force between tilt magnet and tilt yoke is investigated to find the influence on the DC sensitivity in the focus and track directions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.04a
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• pp.195-201
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• 1991

This paper presents appliation of optical moire topography to mesuring force profiles of dies and clay models for practical use in the field of production engineering. Moire topography has been studied intensively during last few decades in the area of optical physics and its mathmatical theory has now been established. In this study, two optical configurations are suggested in which resultant moire fringes can be readily analyzed, so that 3D proviles of the models are constructed through a series of image processing by suing ma chine vision techniques. Experimental results demonstreated by using a micro- computer and CCD camera show 0.05mm measuring spatial resulution, so that the optical method can effectively adopted in order to overcome many difficulties arising when using the existing contact-type digitizing methods.