• Journal of Broadcast Engineering
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• v.24 no.7
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• pp.1246-1258
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• 2019

Since light field (LF) image has huge data volume, it requires high-performance compression technique for efficient transmission and storage of its data. Camera users may like to represent parts of image at different levels of focus at their choice anytime. To address this refocusing functionality, in this paper, we first render a focal stack consisting of multi-focus images, then compress it instead of original LF data. The proposed method has advantage of minimizing the amount of LF data to realize the targeted refocusing applications. Our experiment results show that the proposed method outperforms the state-of-the-art for LF image compression method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.11-22
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• 2022

This paper presents the development process for a high-power diode laser for metal surface hardening. To combine the emissions from several laser bars, it is necessary to collimate the emitted light using an optical lens. Thus, to achieve a suitable power density and uniform beam profile, several optical layouts were proposed. To estimate the laser beam for a flat-top distribution, a numerical analysis was performed using the ZEMAX software, and the results were compared with the experimental results. With a focal lens assembled in a serial diode stack source, the design can utilize the advantage of compacting the overall beam size. Experimental results for a robotic system demonstrated the processing ability of this diode laser module in industrial laser hardening.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.1
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• pp.45-51
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• 2005

We have developed surface micromachined Infrared ray (IR) focal plane array (FPA), in which single $SiO_{2}$ layer works as an IR absorbing plate and $Pb(Zr_{0.3}Ti_{0.7})O_{2}$ thin film served as a thermally sensitive material. There are some advantages of applying $SiO_{2}$ layer as an IR absorbing layer. First of all, the $SiO_{2}$ has good IR absorbance within $8{\sim}12{\mu}m$ spectrum range. Measured value showed about 60% absorbance of incident IR spectrum in the range. $SiO_{2}$ layer has another important merit when applied to the top of Pt/PZT/Pt stack because it works also as a supporting membrane. Consequently, the IR absorbing layer forms one body with membrane structure, which simplifies the whole MEMS process and gives robustness Ito the structure.

• Journal of the Korea Institute of Building Construction
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• v.21 no.5
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• pp.483-493
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• 2021

Urban overcrowding has created an explosive supply and demand for high-rise buildings. High-rise buildings are contributing to enhancing the image of the city by serving as focal points, but due to the stack effect, malfunction of elevator doors, difficulties in opening and closing the doors and windows of the outer wall, smoke and odors spreading to the upper floors, noise, energy loss, fire and pollutants have been causing various unexpected problems such as rapid spread of fire. This study classified high-rise buildings according to their vertical zoning, analyzed the causes of and solutions to the stack effect, and derived design and construction methods. Through the initial plan to block the outside air and securing airtightness through precise construction, we sought ways to secure the airtightness inside and outside the building by actively blocking the airflow from the lower floors. In addition, the facility solution can be a measure to reduce the specific phenomena caused by the stack effect, but it should only be applied to the minimum extent because the potential for secondary damage is high. This study emphasized the need for systematic stack effect management by suggesting design and construction measures for each vertical zoning of the causes and countermeasures of the stack effect. It is expected that this study will be helpful not only for design and construction, but also for building maintenance.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.145-152
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• 2001

For the research of solar EUV (extreme ultraviolet) radiation, we have designed a small-sifted engineering model of solar EUV telescope, which is suitable for a Korean satellite. The EUV sole. telescope was designed to observe the sun at $584.3AA$(He I) and $629.7AA$(OV) The optical system is an f/8 Ritchey-Chr rien, and the effective diameter and focal length are 80mm and 640mm, respectively. The He I and 0V filters are loaded in a filter wheel. In the detection part, the MCP (Microchannel Plate) type is Z-stack, and the channel-to-diameter radio is 40:1. MCP and CCD are connected by fiber optic taper. A commercial optical design software is used for the analysis of the optical system design.