• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2C
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• pp.161-166
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• 2008

In the parallel-architecture turbo codes, the constituent interleaver must avoid memory collision. This paper proposes a collision-free interleaver structure composed of a Latin square matrix and pre-designed interleavers. Our proposed interleavers can be easily optimized for various information block sizes and for various degrees of parallelism. Their performances were evaluated by computer simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.400-401
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• 2015

해상 교통 관제를 함에 있어서 선박간의 충돌 사고를 미연에 방지하기 위해 관제사의 의사 결정을 도울 수 있는 기술들이 많이 개발되고 있다. 관제 시 선박간의 충돌 위험을 판단하고 사고를 미연에 방지하기 위해, 관제사들이 가장 빈번하게 사용되는 기능이 CPA와 거리/방위각 측정기능이다. 하지만, 기존 해상관제 시스템들은 이러한 기능들이 독립적으로 구성되어 있어, 관제사들의 신속한 업무 처리를 방해할 뿐만 아니라, 관제사의 업무 피로도를 종종 증가시킨다. 본 논문에서 제안한 방법은 관제사 설문조사를 통해 수렴된 내용을 토대로 기존의 CPA, 거리/방위각 측정 기능을 보완하여 CPA 계산 시 선박 조우 정보를 제공하고, 관제사로 하여금 충돌예상 선박들에 대해 신속한 초동 조치 지시를 가능하게 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.376-382
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• 2007

A Collapse of bridge by ship's collision to the bridge post may lead a great calamity. This paper investigates on avoiding collision between a ship and bridge by improvement of environmental factors, submitting a counter plan of reducing collision effect by triangular type of collision protecting bar and ship maneuvering skills. Putting up collision protecting bar fences of triangular type around the bridge posts would decrease the collision impact force by 75 percent.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.593-599
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• 2016

Incheon Bridge is 13.38 km long with an 800 m span, connecting Incheon International Airport and Songdo International City, Per hour 73.8 vessels navigate this space. The purpose of this study was to suggest a safe passing speed based on the displacement of a vessel based on the safety criteria of Incheon Bridge's anti-collision fence, which was designed during its initial construction. As AASHTO LRFD suggested, vessel collision energy, vessel collision velocity, and the hydrodynamic mass coefficient were considered to derive a safe vessel traffic speed. Incheon Bridge's anti-collision fence was designed so that 100,000 DWT vessels can navigate at a speed of 10 knot. This research suggests a safe speed for vessel traffic through a comparative analysis of an experimental ship's (300,000 DWT) speed and cargo conditions, regulation speed has been calculated according to the collision energy under each set of conditions. Additionally, safe traffic vessel's safe speed was analyzed with reference to tidal levels. Results from the experimental ship showed that a vessel of maximum 150,000 DWT is able to pass Incheon Bridge at a maximum of 7 knots with an above average water level, and is able to pass the bridge with a maximum of 8 knots under ballast conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.98-106
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• 2006

In order to provide a realtime transmission over a wireless LAM, we here present a new jamming based retransmission mechanism. In a legacy wireless LAN system, all stations use the binary exponential backoff algorithm to avoid collisions among frames. It is well known that the backoff algorithm causes more collisions as the numbers of active stations increases. This makes transmission of real time traffic hard. In the proposed scheme, when each station senses collisions, it promptly allows to send a jamming signal during a unique jamming window period which is determined by its own channel access count database(CACDB). This jamming windows is chosen not to be overlapped each other by using of CACDB, and thus channel access of another station is prevented. Hereafter the station gets the ownership of the medium when the wireless medium becomes idle after sending the jamming signal and sensing carrier, and then sends frame in medium. In our proposal, repeating collisions is never happened. We here assume that real time traffic use a frame of fixed length in order to make the time for receiving its ACK frame same. Comparing the proposed jamming-based retransmission scheme with the the 802.11 and 802.11e MAC by simulation. one can find that the proposed scheme have advantages in terms of delay, average backoff time, and average number of collisions per frame. One can find that the proposed scheme might be practically applicable to several applications of realtime traffic transmission in wireless LAN systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.431-432
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.375-376
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• 2010

• 한국항공운항학회:학술대회논문집
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• 2005.11a
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• pp.146-150
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• 2005

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.363-363
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.364-364
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• 2006