• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.421-424
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• 2004

한국 동해시 연안역에서 2001년 6월, 2003년 5월 및 2004년 5월 해상실험 및 실시간 모니터링 부이 시스템을 통해 수집된 해양관측(수온, 유속)자료와 SAR (Synthetic Aperture Radar)위성영상을 분석한 내부파의 물리적 특성을 정리하였다. 이를 토대로 음파전달 모델(RAM)을 통해 내부파에 의한 음파전달 영향을 파악하고, 음도파관 불변 이른(Waveguide invariant theory)을 적용하여 내부파에 의한 해양 변동성을 음향학적으로 정량화 하였다.

• Journal of Astronomy and Space Sciences
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• v.24 no.3
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• pp.219-226
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• 2007

Among the interplanetary shock (IP shock)s observed by ACE spacecraft at 1AU during 1997 to 2000, we have selected 31 IP shocks which had triggered the interplanetary type II radio bursts detected by the WIND spacecraft while those shocks were leaving the Sun. We compared the observed IP shock propagation speeds and the IP shock transit speeds estimated by time difference between the interplanetary type II radio burst detection and the IP shock observation. Then, we found that the mean acceleration of the IP shocks between the Sun and the Earth is about $-1.02m/sec^2$, which means the deceleration contrary to the positive acceleration predicted by Parker solar wind model. It is also verified that the acceleration of the IP shock does not show any linear correlation with the shock propagation speed and the Mach number of the IP shock.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.141-144
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• 2021

최근 지상파 UHD 방송에서는 자막을 비디오 패킷에 삽입하여 전달하는 기존 방식이 아닌 별도의 전송로로 전달하는 폐쇄형 자막(closed caption) 방식을 적용하고 있다. 또한 자막에는 문자 뿐만 아니라 이미지까지 포함하여 청각장애인의 프로그램 이해도를 높이는데 활용할 수 있다. 따라서 본 논문에서는 청각장애 시청자가 방송 콘텐츠 내용의 이해도를 향상시키기 위하여 지상파 UHD 방송에서 기존의 문자 자막과 움직이는 이미지 자막(=감정표현 자막)을 송출하여 동시에 표현할 수 있는 송출시스템을 제안한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.270-272
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• 2010

재난 상황에서 국민의 생명과 재산을 보호하기 위해서는 재난 관련 정보를 빠르고 정확하게 전달할 수 있는 시스템이 필요하다. 지상파 DMB는 개인용, 휴대용, 이동형, 디지털 멀티미디어, 방송 매체라는 특징을 가지는 재난경보를 전달하는 데 매우 적합한 매체로서, 이를 위해 지상파 디지털멀티미디어방송(DMB) 재난경보방송 표준이 2006년에 제정되었다. 현재 지상파 DMB를 통한 재난경보방송 송출은 기술적으로는 준비가 완료되었으나, 이를 지원하는 단말기는 출시되어있지 않다. 본 논문에서는 지상파 DMB 재난경보방송 수신기의 재난 메시지 처리과정 중 재난 정보 알림 단계를 분석하였다. 본 논문의 내용은 지상파 DMB 재난경보방송 수신기를 개발하는 데 활용할 수 있을 것이다.

• Computational Structural Engineering
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• v.9 no.1
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• pp.55-64
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• 1996

Sloshing frequencies of the fluid in rectangular tanks with a bottom-mounted rectangular block are determined by linear water wave theory. Velocity potential is decomposed into those for the wall-induced waves, and the reflected, transmitted, and scattered waves by the block. The reflection and transmission coefficients are determined using the continuity conditions of mass flux and energy flux on the common vertical boundaries of the fluid regions, and the boundary conditions on the both sides of the block. The analysis results indicate that the sloshing frequencies reduce, as the block becomes tall and vade and as the block moves toward the center. The variations of the sloshing frequencies due to the block are found to be more sensitive in broad thanks than is tall tanks.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3
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• pp.213-220
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• 2002

The sound wave in the sea propagates under the effect of water depth, sound velocity structure, sea surface and bottom roughness, and bottom sediment distribution. In particular the sound velocity structure in shallow water varies with time and space, an? the sediment distributes very variedly with place. In order to investigate the seasonal variation of low-frequency sound propagation in the Yellow Sea, the propagation experiments were conducted along the same track in the middle part of the Yellow Sea at various seasons of spring. summer, and autumn. In this paper we consider the measurement results on the propagation loss with the sound velocity structure, and investigate the seasonal variation of the propagation loss. As a result, the propagation losses measured in summer were larger than the losses in spring and autumn. And the propagation losses measured in autumn were smaller than the losses in spring. The seasonal change of the propagation loss increased with the rise of sound frequency and the propagation range.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.385-388
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• 2019

Considering spherically symmetric spacetimes embedded in a 5-dimensional static Lorentzian manifold, within the large distance limit of DGP model, we study null geodesic equations. We discuss possible relations of particles following the geodesics with the gravitational waves detected recently, in comparison with the electromagnetic waves propagaing in these brane spacetimes.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.172-180
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• 2013

The focus of this study is to provide a method for determining the dimension of a submerged breakwater satisfying the target transmission performance or predicting the transmission coefficient of a given structure. This method was developed based on data analysis of the physical experiment that was carried out by using the submerged breakwater composed of double-layer permeable blocks. Two different armor blocks of Tetrapod and Triangular Pyramid Block were used in the experiment. The parameter $K_Th_b/h$ was introduced in the analysis of the measurement data. By using the linear regression line deduced from the analysis of the experimental data, it was possible to readily predict the wave transmission coefficient irrespective different water depths at the crest of the submerged breakwater, under the condition of significant decrease in transmitted wave height due to the submerged breakwater. This method can be effectively utilized for estimating the necessary number of blocks used for the submerged breakwater as well as comparing the transmission characteristics of the submerged breakwater according to use of different armor blocks.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.122-129
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• 2002

The analytical models and algorithm of the SPIKE code, which has been developed by KAERI's KALIMER team to investigate the sodium-water reaction phenomena in the liquid metal reactor, were introduced with its verification calculation results. The sodium water reaction of KALIMER IHTS was evaluated. Early stage of the sodium-water reaction consists of wave and mass transfer regimes. The pressure variations were independent of specific design features in the wave transfer regime. However in the mass transfer regime, the pressure variations were strongly dependent on cover gas volume and rupture disk set pressure. The early stage SWR analysis showed that the KALIMER IHTS with an appropriate cover gas volume and rupture disk set pressure had enough margin to its design pressure.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.317-320
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• 2009

재난 상황에서 생명과 재산을 보호하기 위해서는 각종 재난 관련 정보를 빠르고 정확하게 전달할 수 있는 시스템이 필요하다. 지상파 DMB는 개인용, 휴대용, 이동형, 디지털 멀티미디어, 방송 매체라는 특징을 가지며, 이는 재난경보를 전달하는 데 매우 적합하다. 이 논문의 목적은 지상파 DMB 재난경보방송 수신기가 가져야 할 기능적 요구사항을 도출하는 것이다. 이를 위해서 먼저 수신기 이용 시나리오를 연구하였다. 이를 바탕으로 재난 메시지 처리 프로토콜 스택을 정의하고, 각 프로토콜 스택이 가져야 할 요구사항을 도출하였다. 이 논문의 내용은 지상파 DMB 재난경보방송 수신기를 개발하는 데 활용할 수 있을 것이다.