• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.145-150
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• 2004

The LED lighting used spot-light illuminate the limited surface. So it is a key-point to condense wide emission angle of high power light emitting diodes (LEDs) to narrow that angle. In this paper, the secondary optics was designed by lens-makers formula for concentration rays of LED into specific region. So, it simulated the optics that designed by lens makers-formula in the optical design program, LightTools. And then, show the p propriety of lens design utilizing simulation result, luminous intensity, emission angle.

• Journal of the Korean Vacuum Society
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• v.3 no.2
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• pp.186-189
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• 1994

Si(111)-7x7 표면에 Sn을 증착시킬 때 기판온도와 증착량에 따른 표면구조의 변화를 RHEED상 (pattern)과 RHEED상의 회절반점(spot) 강도변화를 관찰하여 조사하였다. Si(111) 기판오도를 $ 400^{\circ}C$로 유지하면서 Sn을 증착시킬 때{{{{ SQRT { 3}$\times$ SQRT { 3} 구조가 관찰되었으며 기판온도 $200^{\circ}C$ 이하에서는 증착량에 따라 {{{{ SQRT { 3}$\times$ SQRT { 3} }}, {{{{2 SQRT { 3} $\times$2 SQRT { 3} }}, 구조들이 관찰되었다. RHEED 반점의 강도변화를 이용하여 Si(111)-Sn {{{{ SQRT { 3}$\times$ SQRT { 3} 서의 Sndnjs자의 이탈과정을 조사한 결과 이탈에너지는 $3.3pm$0.1 eV로 조사되었다.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.107-109
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• 2004

High-resolution remotely sensed data such as SPOT-5 imagery are employed to study the effectiveness of the watershed segmentation algorithm. Existing problems in this approach are identified and appropriate solutions are proposed. As a case study, the panchromatic SPOT-5 image of part of Beijing urban areas has been segmented by using the MATLAB software. In segmentation, the structuring element has been firstly created, then the gaps between objects have been exaggerated and the objects of interest are converted. After that, the intensity valleys have been detected and the watershed segmentation have been conducted. Through this process, the objects in an image are divided into separate objects. Finally, the effectiveness of the watershed segmentation approach for high-resolution imagery has been summarized. The approach to solve the problems such as over-segmentation has been proposed.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.274-277
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• 2003

Millimeter-wave networking is composed of narrow beam link. High directivity of the beam provides either advantage or disadvantage in comparison with conventional wide-lobe microwave communications. In such networks, it is very substantial that beam connecting point to point is fixed in right direction. It is major requirement in the beam network to keep the beam in best direction. In this paper, We propose the method to find a best suited direction of the antenna's beam using the Genetic Algorithm in point-to-point link. Proposed method presume that each station knows his direction $\theta$$_1$,$\theta$$_2$ at every step of Genetic Algorithm, then it can be expected that GA is possible to search the ideal solution. Intensity of the received signal is evaluated by the multiplication of lengths to the point which the lobe meets with the horizontal line.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.152-162
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• 1996

Diffraction gratings were designed to generate multiple beams for the real-time optical interconnection in free-space using a liquid crsytal television. Multi-level phase gratings consisted of stepped phase value, 0 to 2$\pi$, and generate a 5$\times$5 spot array, and V-shaped spot patterns which have a maximum diffraction efficiency of 78.84%. Simulated annealing technique was used to determine phase states of each pixel having uniform intensity and high diffraction efficiency. Through the optical interconnection experiments, we compared the diffraction characteristics of beam paterns obtained by binary-level, four-level, and eight-level phase gratings.

• Transactions of the Society of Information Storage Systems
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• v.2 no.1
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• pp.1-6
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• 2006

An optical ROM card system which using an optical probe array generated by Talbot effect was proposed as new robust storage solution. To improve the optical density and to decrease the power consumption of the system, it is very important to make the spot sizes of optical probes smaller as well as to increase the optical efficiency from the light source to optical probes. In this study, a microlens illuminated aperture array for generating high efficiency optical probe away with small beam spot was designed and fabricated using monolithic lithography integration method. The maximum intensity of optical probes of microlens illuminated aperture array increased about 12 times of that of aperture array, and the full width half maximum of the optical probe at Talbot plane generated by microlens illuminated aperture array was $0.77{\mu}m$.

• Korean Journal of Remote Sensing
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• v.16 no.3
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• pp.235-242
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• 2000

This paper presents a method to detect buildings using shadow information in satellite imagery. We classify image into three categories of building region, shadow region and background region to find buildings with consistent intensity. After the removal of noises in building regions and shadow regions, buildings adjacent to shadow regions are detected using the constraint of building and shadow sizes. The algorithm has been applied to KOMPSAT and SPOT images and the result showed buildings are efficiently detected.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.4
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• pp.451-455
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• 2001

The epitaxial growth of Ge on the clean and surfactant(Sn) adsorbed surface of Ge(111) was studied by the intensity oscillation of a RHEED specular spot. In the case of epitaxial growth without the adsorbed surfactant, the RHEED intensity oscillation was stable and periodic up to 24ML at the substrate temperature of $200^{\circ}C$. Therefore the optimum temperature for the epitaxial growth of Ge on clean Ge(111) seems to be $200^{\circ}C$. However, in the case of epitaxial growth with the adsorbed surfactant, the irregular oscillations are observed in the early stage of the growth. The RHEED intensity oscillation was very stable and periodic up to 38ML, and the $d2{\times}2$ structure was not charged with continued adsorption of Ge at the substrate temperature of $200^{\circ}C$. These results may be explained by the fact that the diffusion length of Ge atoms is increased by decreasing the activation energy of the Ge surface diffusion, resulted by segregation of Sn toward the growing surface. From the desorption process, the desorption energy of Sn in Ge $\sqrt{5}{\times}\sqrt{5}$ structure is observed to be 3.28eV.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.132-142
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• 2014

In this paper, we propose a traffic lights detection method using visual attention and spot-lights detection. To detect traffic lights in city streets at day and night time, the proposed method is used the structural form of a traffic lights such as colors, intensity, shape, textures. In general, traffic lights are installed at a position to increase the visibility of the drivers. The proposed method detects the candidate traffic lights regions using the top-down visual saliency model and spot-lights detect models. The visual saliency and spot-lights regions are positions of its difference from the neighboring locations in multiple features and multiple scales. For detecting traffic lights, by not using a color thresholding method, the proposed method can be applied to urban environments of variety changes in illumination and night times.

• Conservation Science in Museum
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• v.4
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• pp.71-78
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• 2003

The wooden striker on the Divine Bell of King Seongdeok was examined to identify the species of the wood and the outdoor wood weathering caused by solar light, moisture, temperature and air. The species of the wooden striker was identified to Zelkova serrata. When observed the striker with naked eyes, the results were surface discoloration (graying), cracking and roughness. In order to examine the morphological changes according to deterioration type, the specimen were separated to three part(I, II,III-spot). The I-spot was discolored to gray and at the same time entirely covered with dust. So the observation was impossible. The II-spot was also discolored but its texture could be observed. On it could observe numerous fungal hypae and dirts like dust flown into the cell lumens. The cell wall has been so weakened by weathering that it lost the physical intensity. This have made microchecks and splits on the cell wall. Although fungal hypae covered the cell, they did not result in wood decay. The III-spot, located just 0.5 mm below the surface, was maintaining the natural red-brown color of the wood. Its cell wall was similar to that of sound wood. These changes are different from wood decay, and limited only to the surface of the striker-less than or equal to 0.5 mm below.