• Title/Summary/Keyword: Lee Sang Hyuk

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Design of Digital Logic for Passive RFID(Type B) Tag (Passive RFID(Type B) 태그 Digital Logic 설계)

  • Lee, Seung-Hyuk;Cho, Tae-Kyung
    • Proceedings of the KAIS Fall Conference
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    • 2006.05a
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    • pp.453-456
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    • 2006
  • 본 논문은 유비쿼터스 컴퓨팅 시대를 열어가는 유비쿼터스의 핵심 기술인 RFID 시스템의 구성요소 중 하나인 Type B RFID 태그를 설계하였다. RFID 태그는 전원공급 여부에 따라 능동형과 수동형으로 구분한다. 본 논문에서는 현재의 IT분야에서의 RFID 시장과 연구동향에 맞춰 수동형 Type B RFID 태그의 Digital 파트를 설계하고, 성능을 검증하였으며, 향후 RFID 시스템의 연구방향에 대해서도 제시하였다.

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PROTO-MODEL OF AN INFRARED WIDE-FIELD OFF-AXIS TELESCOPE

  • Kim, Sang-Hyuk;Pak, Soo-Jong;Chang, Seung-Hyuk;Kim, Geon-Hee;Yang, Sun-Choel;Kim, Myung-Sang;Lee, Sung-Ho;Lee, Han-Shin
    • Journal of The Korean Astronomical Society
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    • v.43 no.5
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    • pp.169-181
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    • 2010
  • We develop a proto-model of an off-axis reflective telescope for infrared wide-field observations based on the design of Schwarzschild-Chang type telescope. With only two mirrors, this design achieves an entrance pupil diameter of 50 mm and an effective focal length of 100 mm. We can apply this design to a mid-infrared telescope with a field of view of $8^{\circ}{\times}8^{\circ}$. In spite of the substantial advantages of off-axis telescopes in the infrared compared to refractive or on-axis reflective telescopes, it is known to be difficult to align the mirrors in off-axis systems because of their asymmetric structures. Off-axis mirrors of our telescope are manufactured at the Korea Basic Science Institute (KBSI). We analyze the fabricated mirror surfaces by fitting polynomial functions to the measured data. We accomplish alignment of this two-mirror off-axis system using a ray tracing method. A simple imaging test is performed to compare a pinhole image with a simulated prediction.

History of Fan Ji and Yi Ji (번적과 익적의 역사)

  • Hong, Sung-Sa;Hong, Young-Hee;Chang, Hye-Won
    • Journal for History of Mathematics
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    • v.18 no.3
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    • pp.39-54
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    • 2005
  • In Chinese Mathematics, Jia Xian(要憲) introduced Zeng cheng kai fang fa(增乘開方法) to get approximations of solutions of Polynomial equations which is a generalization of square roots and cube roots in Jiu zhang suan shu. The synthetic divisions in Zeng cheng kai fang fa give ise to two concepts of Fan il(飜積) and Yi il(益積) which were extensively used in Chosun Dynasty Mathematics. We first study their history in China and Chosun Dynasty and then investigate the historical fact that Chosun mathematicians Nam Byung Gil(南秉吉) and Lee Sang Hyuk(李尙爀) obtained the sufficient conditions for Fan il and Yi il for quadratic equations and proved them in the middle of 19th century.

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A Numerical Analysis of Flow and Heat Transfer in the Plate Heat Exchanger with Dimple (딤플형 판형 열교환기의 열유동 수치해석)

  • Ahn, Hyuk-Jin;Lee, Sang-Hyuk;Lee, Myung-Sung;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.121-125
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    • 2008
  • In this study, the characteristics of internal flow and the heat transfer performance of dimpled plate heat exchanger were numerically investigated. For the numerical analysis, conjugate heat transfer method between cold fluid - plate - hot fluid was studied with appropriate boundary conditions. Velocity magnitude, temperature and pressure distribution were obtained from the simulation. Correlations for fanning f-factor and Colburn j-factor were obtained from numerical results and compared to the experimented data.

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