• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.118-119
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• 2006

현재의 소자간 연결을 위해 사용되는 금속배선의 한계로 인해 보다 고속/대용량의 광연결(Optical Interconnection)이 크게 각광받고 있다. 본 논문에서는 FEM 시뮬레이션(Finite Element Method Simulation)을 통해 온도변화에 따른 기판에서의 온도분포를 살펴보고, 열응력 분포와 열응력 집중에 의한 기판의 변형으로 인한 문제를 연구하였다. 이를 통해 향후 Optical Passive Component 설계시 Optical Passive Component 변형의 원인이 될 수 있는 열원들의 배치를 최적화 시키고 기판의 취약부운을 보강하여 우수한 성능의 Optical Passive Component 제작을 목표로 하고 있다.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.260-266
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• 1997

Holographic optical elements for polarization separation (HPS) are fabricated in a dichromated gelatin(DCG) thin film of 7${\mu}{\textrm}{m}$ thickness. The polarization properties of HPS is characterized by measuring diffraction efficiency with several physical parameters like exposure time, incident angle and read-out polarization angles. The experimental data are compared with theoretical results based on Kogelnik's coupled wave theory, which shows good agreement. It is also found that the HPS element has a very high extinction ratio of polarization over 500:1 for S and P polarizations, respectively, with He-Ne laser wavelength. We also propose an optical switch optical interconnects by using HPS elements.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.250-253
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• 2015

High contrast grating (HCG) is the structure made up of the sub-wavelength grating of high-index and the surrounding layer of low-index, which reveals high contrast between two materials. Its advantages include high reflectivity over a broad bandwidth, polarization and wavelength selectivity, optical high-Q resonator, and phase modulation. In this work, the HCG structure comprising of indium tin oxide (ITO) and Silicon (Si), for the surrounding layer and the grating layer respectively, was studied. Its theoretical model was established, and transmittance, phase and optical behavior were calculated by rigorous coupled-wave analysis and finite element method. Furthermore, the established structure was fabricated to validate its feasibility. The fabricated structure shows the focusing capability whose length is about $10{\mu}m$, and the feasibility of the structure was demonstrated. It is also meaningful that ITO layer can contribute to the fabrication of the HCG structure, leading to enable the structure to be electrical-driven.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.175-183
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• 2001

Various welding processes are now available for end cap closure of nuclear fuel element such as TG(Tungsten Inert Gas) welding, magnetic resistance welding and laser welding. Even though the resistance and TIG welding processes are widely used for manufacturing commercial fuel elements, they can not be recommended for the remote seal welding of a fuel element at a hot cell facility due to the complexity of electrode alignment, difficulity in the replacement of parts in the remote manner and a large heat input for a thin sheath. Therefore, the Nd:YAG laser system using optical fiber transmission was selected for Zircaloy-4 end cap welding inside hot cell. The laser welding apparatus was developed using a pulsed Nd:YAG laser of 500 watt average power with optical fiber transmission. The weldability of laser welding was satisfactory with respect to the microstructures and mechanical properties comparing with TIG and resistance welding. The optimum operation processes of laser welding and the optical fiber transmission system for hot cell operation in a remote manner have been developed The effects of irradiation on the properties of the laser apparatus were also being studied.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.104-109
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• 2001

With the increase of storage density and data transfer rates in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. However, there are still a lot of difficulties in the use of designing the rubber components with complex shape and under pre-deformed state. It was demonstrated in that the variation of rubber component stiffness with the pre-deformed state were calculated by the finite element method and the reliability of numerical results were checked by compared with the measuring the deflection values. This paper presents a efficient design method of rubber mounts for anti-vibration of an optical disk thrive. With an empirical equation to estimate elastic modulus from hardness, and dynamic characteristics of rubber material of a cylindrical shape, this method is capable of predicting the dynamic characteristics of rubber components at design stage.

• Journal of KSNVE
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• v.9 no.2
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• pp.324-330
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• 1999

With the increase of track density, high rotational speed and the compatibility for various media such as CD-ROM, CD-R/RW, DVD-ROM/RAM/RW etc. in optical disk drive, the effective anti-vibration design is so crucial for robust operaton. Especailly when the drive is self-excited by unbalanced disk, internal sled base vibration and its external transmission to the case bring about so severe problem. Generally these two consideration points the practical anti-vibration design process to control thses two conflictive properties using finite element analysis. As an example of the design process, Duro 25 and 40 visco-elastic rubber mount was selected and analyzed. The stiffness obtained from FEM rubber model was well matched with the experiments. Also it was confirmed that the internal and external vibration induced from unbalanced disk have good agreement with experimental results. The proposed design process is adopted to the slim-type optical disk drive.

• Current Optics and Photonics
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• v.7 no.4
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• pp.435-442
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• 2023

These days, the size of a reflective telescope has been increasing for astronomical observation. An additional optical system usually assists a large ground telescope for image analysis or the compensation of air turbulence. To guide collimated light to the external optical system through a designated path, a coudé mirror is usually adopted. Including a collimator, a coudé mirror of a ground telescope is affected by gravity, depending on the telescope's pointing direction. The mirror surface is deformed by the weight of the mirror itself and its mount, which deteriorates the optical performance. In this research, we propose an optimization method for the coudé mirror assembly for a 1-m class ground telescope that minimizes the gravitational surface error (SFE). Here the mirror support positions and the sizes of the mount structure are optimized using finite element analysis and the response surface optimization method in both the horizontal and vertical directions, considering the telescope's altitude angle. Throughout the whole design process, the coefficients of the Zernike polynomials are calculated and their amplitude changes are monitored to determine the optimal design parameters. At the same time, the design budgets for the thermal SFE and the mass and size of the mount are reflected in the study.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.227-231
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• 1990

A SiO2/Si concave diffraction grating(period: 1.3${\mu}{\textrm}{m}$) for the angular dispersive element of WDM was fabricated by sandwiching the SiO2/Si plane diffraction grating between a slab waveguide and a cylindrical concave block. Using this concave grating and input/output fiber, and wavelength division demultiplexer was composed. The demultiplexer has five channels, the insertion loss of 30dB, the wavelength spacing per channel of 7nm and crosstalk of-15dB.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.97-101
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• 2002

The optical current transformer using Faraday effect is the sensor to measure current that flows in any conductor. This sensor doesn't undergo the magnetic saturation and effect of adjacent conductors. But this senor using bulk-glass sensing element has crucial drawback. It is impossible that the sensor is mounted to conductor without breaking the closed-loop of light or conductor. So we developed the clamp-type optical current transformer and made an experiment.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.162-167
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• 1991

홀로그램 광학소자(holographic optical element)의 일종인 holographic collimating lens(HCL)를 최적 설계하였으며, 중크롬산 젤라틴 필름을 사용하기 최적 설계치에 따라 HCL을 제작하였고 그 성능을 평가하였다. off-axis 방식의 holographic zone plate (HZP) 구조를 채택하였으며, 기록광과 재생광의 파장 차이에 의한 색수차를 최소화시키기 위해 유한 광선 추적법과 감쇠 최소자승법으로 최적 설계하였다. Dipping 법으로 제작된 중크롬산 젤라틴(Dichromated Gelatin, DCG) 필름을 기록 매질로 사용하여 HCL을 제작하였으며 회절광의 집적도를 측정하여 그 성능을 평가하였다.