• Journal of the Korean Institute of Navigation
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• v.22 no.2
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• pp.39-45
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• 1998

CATV(Cable Television) 및 MATV(Master Antenna TV) 시스템용 신호분기기(Tap-Off)의 광대역설계법을 새로운 방법으로 제안한다. 먼저 결합선로형 방향성결합기의 이론을 도입하여 변성기형 방향성결합기에 적용하여 해석하였다. 제안한 해석방법의 타당성을 입증하기 위하여 시뮬레이션한 결과와 실험결과를 비교 검토하였고 전송선로의 임피던스를 매칭시켜 반사계수 20dB, isolation 25dB(5∼1600MHz)을 만족하는 신호분기기(14dB)의 광대역화(5∼2150MHz)를 실현하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1993.10a
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• pp.25-32
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• 1993

The design theory of a generalized n-way power divider with arbitrary dividing rations for CATV and/or MATV systems which consists of ideal multi-winding transformers and resistors only was presented. Since the circuit elements have not frequency dependence the proposed power divider is to be of exetremely broad band-width. Furthermore as a result of computer simulation the frequency characteristics are very good in spite of errors of turn numbers and hence it was confirmed that the proposed design theory is valid.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.65-67
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• 2021

국내 지상파 방송의 경우 2027년에 DTV를 종료하고 UHDTV로 완전 전환이 될 예정이다. 이러한 일정을 감안하면 기존 DTV 수상기를 보유한 가정에서는 UHDTV를 수신할 수 없어 TV를 시청할 수 없는 문제가 발생한다. 이를 위해서는 UHD 서비스를 DTV 서비스로 변환하여 제공할 수 있는 공시청 시스템 개발이 요구되는데, 본 논문은 이러한 공시청 시스템에서 UHDTV의 서비스 및 프로그램 정보를 DTV의 PSI/PSIP 정보로 변환하는 방법에 관한 것이다.

• Structural Engineering and Mechanics
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• v.72 no.4
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• pp.421-432
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• 2019

In high-speed railway (HSR) system, the structure-borne noise inside viaduct at low frequency has been extensively investigated for its mitigation as a research hotspot owing to its harm to the nearby residents. This study proposed a novel acoustic optimization method for declining the structure-borne noise in viaduct-like structures by separating the acoustic contribution of each structural component in the measured acoustic field. The structural vibration and related acoustic sourcing, propagation, and radiation characteristics for the viaduct box girder under passing vehicle loading are studied by incorporating Finite Element Method (FEM) with Modal Acoustic Vector (MAV) analysis. Based on the Modal Acoustic Transfer Vector (MATV), the structural vibration mode that contributes maximum to the structure-borne noise shall be hereinafter filtered for the acoustic radiation. With vibration mode shapes, the locations of maximum amplitudes for being ribbed to mitigate the structure-borne noise are then obtained, and the structure-borne noise mitigation performance shall be eventually analyzed regarding to the ribbing conduction. The results demonstrate that the structural vibration and structure-borne noise of the viaduct box girder mainly occupy both in the range within 100 Hz, and the dominant frequency bands both are [31.5, 80] Hz. The peak frequency for the structure-borne noise of the viaduct box girder is mainly caused by $16^{th}$ and $62^{th}$ vibration modes; these two mode shapes mainly reflect the local vibration of the wing plate and top plate. By introducing web plate at the maximum amplitude of main mode shapes that contribute most to the acoustic modal contribution factors, the acoustic pressure peaks at the field-testing points are hereinafter obviously declined, this implies that the structure-borne noise mitigation performance is relatively promising for the viaduct.