• 한국통신학회논문지
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• 제36권5B호
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• pp.517-529
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• 2011

본 논문에서는 차세대 해상 통신 시스템인 SANET (Ship Ad-hoc NETwork)의 우선 전송 규격 파라미터를 설정하고, VHF 대역의 실측 해상 채널을 분석하여 SANET 채널 모델링을 수행한다. 또한, 프리앰블, guard time, 파일롯을 포함한 단일 및 다중 반송파 시스템을 위한 프레임 구조를 제안하며, 제안된 프레임 구조 하에서 채널 보상과 채널 부호화 기법에 의한 SANET 시스템의 BER (Bit Error Rate) 성능을 평가 및 분석한다. 결과로 ${\pi}$/4-DQPSK와 ${\pi}$/8-D8PSK를 적용한 단일 반송파 SANET의 경우, differential 변조방식 채택에 의하여 별도의 채널 보상을 하지 않으며, 부호화 이득을 얻을 수 있는 컨볼루션 부호화를 적용하기로 한다. 다중 반송파 SANET의 경우에는 해상환경, 파도에 의한 선박의 움직임 등에 의한 K값의 변화를 고려하여 시스템의 성능을 최대화 하도록 채널 보상 기법과 컨볼루션 부호화를 적용한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권6호
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• pp.1659-1674
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• 2024

Conventional maritime communication struggles to provide high data rate services for Internet of Things (IoT) devices due to the variability of maritime environments, making it challenging to ensure consistent connectivity for onboard sensors and devices. To resolve this, we perform mathematical modeling of the maritime channel and compare it with real measurement data. Through the modeled channel, we verify the received beam gain at buoys on the ocean surface. Additionally, leveraging the modeled wave motions, we estimate future angles of the buoy to use the Extended Kalman Filter (EKF) for design beamforming strategies that adapt to the evolving maritime environment over time. We further validate the effectiveness of these strategies by assessing the results from an outage probability perspective. focuses on improving maritime communication by developing a dynamic model of the maritime channel and implementing a Kalman filter-based buoy motion tracking system. This system is designed to enable precise beamforming, a technique used to direct communication signals more accurately. By improving beamforming, the aim is to enhance the quality of communication links, even in challenging maritime conditions like rough seas and varying sea states. In our simulations that consider realistic wave motions, you've observed significant improvements in link quality due to the enhanced beamforming technique. These improvements are particularly notable in environments with high sea states, where communication challenges are typically more pronounced. The progress made in this area is not just a technical achievement; it has broad implications for the future of maritime communication technologies. This paper promises to revolutionize the way we approach communication in maritime environments, paving the way for more reliable and efficient information exchange on the seas.

• 한국항해항만학회지
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• 제29권3호
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• pp.181-187
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• 2005

국내 최초로 운항예정인 수륙양용 아쿠아버스의 운항 리스크를 낮추고 안전을 확보하기 위하여 운항예정 해역인 월미도와 영종도간 수로에 대한 자연적환경과 해상교통량을 조사하고, 그들의 위험요소를 분석하였다. 그리고 아쿠아버스의 통항 안전 확보를 위하여 경계수역 지성, 잔용선착장 설치, 운항관리 방안 등을 제안하였다.

• 한국통신학회논문지
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• 제38C권3호
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• pp.288-295
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• 2013

본 논문에서는 4S (Ship to Ship, Ship to Shore) 해상통신을 위해 다른 채널 조건 하에서 기존의 채널 추정 기법을 비교하였다. 일반적으로 수신 신호는 다중경로나 부호 간 간섭에 의해 손상을 받게 된다. 시간 변화 다중 페이딩 채널의 추정은 수신기에서 어려운 작업이며, 적절한 채널 추정 필터를 사용함으로써 수신기의 성능을 향상시킬 수 있다. 모의실험은 MATLAB을 사용하여 AWGN (Additive White Gaussian Noise), Rician, Rayleigh 채널에서 채널 추정 알고리즘으로 주로 사용되어지는 LMS (Least Mean Square)와 RLS (Recursive Least-Squares) 알고리즘을 비교 하였다.

• 한국항해항만학회지
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• 제48권2호
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• pp.88-96
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• 2024

This study examined challenges posed by two ferry routes, namely, Likoni and Mtongwe crossings, in the Mombasa Channel and their impact on navigational safety. Utilizing the Environmental Stress (ES) model, this study analyzed current ship traffic and assessed stress levels imposed by ferry crossing traffic on navigators. ES values revealed significant stress at these ferry crossings attributed to varying transit speeds. Standardizing transit speeds at two ferry passages can reduce high stress levels, presenting a viable solution. Furthermore, the IWRAP Mk2 simulation underscores crossing collisions as a significant concern, particularly at Likoni and Mtongwe crossings, due to increased ferry traffic. This research offers valuable insights for stakeholders, such as the Kenya Ports Authority (KPA), to develop targeted safety measures and enhance the flow of ship traffic in the channel.

• 한국항해항만학회지
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• 제40권5호
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• pp.257-263
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• 2016

Mombasa is the principle port of Kenya, serving inland countries in Eastern and central Africa. Mombasa port has undergone a massive infrastructure upgrade and dredging works with an expectation that more vessels and large post Panamax ships will be able to enter Mombasa port. Therefore, it is vital to carry out a marine traffic risk assessment in order to quantify the degree of navigation safety needed in the Mombasa approach channel and also to evaluate the navigation risk imposed on transit traffic by local ferry traffic. In this paper, a marine traffic risk assessment is carried out using the IWRAP mk2, Environmental Stress (ES) model, and the PARK model. Risk assessment results show that Likoni area has an unacceptable stress/risk ranking at 20.7% by the ES model and 38.89% by the PARK model. The IWRAP mk2 model shows that the crossing area has the highest risk of crossing collision and the area at the entrance to the inner channel has a high risk of grounding. The conclusions derived from this study will provide the basis for proposing the most effective countermeasure to improve navigation safety in the Mombasa approach channel.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2016년도 춘계학술대회
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• pp.81-84
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• 2016

Mombasa is the principle port of Kenya, serving hinter countries in Eastern and central Africa. Mombasa port has undergone a massive infrastructure upgrade and dredging works with an expectation that more vessels and large post Panamax ships will be able to call at Mombasa port. Therefore, it is vital to carry out a marine traffic risk assessment so as to quantify the degree of navigation safety on Mombasa approach channel and also to evaluate navigation risk imposed on transit traffic by local ferry traffic. In this paper marine traffic risk assessment is carried out using IWRAP mk2, Environmental Stress model, and PARK model. Risk assessment results show that Likoni area has unacceptable stress/ risk ranking at 20.7% on ES model and 38.89% by PARK model. IWRAP mk2 model shows that crossing area has the highest risk of crossing collision and the area at the entrance to inner channel has a high risk of grounding. The conclusions derived from this study will provide the basis for proposing the most effective countermeasure so as to improve navigation safety in Mombasa approach channel.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.165-169
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• 2007

Due to the complexity of underwater acoustic channel, signal estimation in underwater acoustic communication field is considerably affected from time-varying multipath fading channels. On this reason, the original signals should have many long training signals to estimate the channel and the purposed signals, and the bit rate of signals having information may have small rate. In order to avoid this loss of efficiency in underwater communication, this paper employed a blind channel identification method which don't use training signals. Simulations have predicted performance of the employed method in multipath environment and an aquatic plant experiment has verified the simulation results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.4002-4014
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• 2015

ITU-R M.1842-1, as a well-known specification dedicated to maritime mobile applications, has standardized wireless transmission protocols according to the particular characteristics of a maritime communications scenario. A time division multiple access (TDMA) frame structure, along with modulation schemes to achieve a high data rate, has been described clearly in ITU-R M.1842-1. However, several specification items are still under "to be decided" status, which brings ambiguity to research works. In addition, the current version of ITU-R M.1842-1 is focused mainly on maritime transmissions in open-sea areas, where the cyclic prefix (CP) is set to zero and only 16-QAM is used in the multi-carrier (MC) system. System performance might be dramatically degraded in coastline areas due to the inter-symbol interference (ISI) caused by selective fading. This is because there is a higher probability that the signal will be reflected by obstacles in coastline areas. In this paper, we introduce the transmission resource block (TRB) dedicated to ITU-R M.1842-1 for a ship ad-hoc network (SANET), where the pilot pattern of TRB is based on the terrestrial trunked radio (TETRA). After that, we evaluated SANET performance under the maritime channel model in a coastline area. In order to avoid noise amplification and to overcome the ISI caused by selective fading, several strategies are suggested and compared in the channel estimation and equalization procedures, where the link-level simulation results finally validate our proposals.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.237-243
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• 2005

항만의 계획 및 개발단계에서 중요한 요소 중 하나는 항로의 설계이다. 항로를 설계할 때 가능한 한 굴곡부를 피해야 하지만, 그렇지 못할 경우에는 변침과정에서 추가적으로 발생하는 항과면적의 증가를 고려하여 항로의 폭을 확장하고 항로를 배치하는 것이 선박의 안전한 통항에 필수적이다. 본 연구에서는 가변범퍼영역모델을 이용하여 굴곡부에서의 항로의 폭과 항로의 배치를 결정하는 기법을 다룬다. 모델실험결과 굴곡부 중심교각이 30도 미만인 경우 굴곡부 항로의 폭을 확장할 필요가 없는 것으로 분석되었으며, 굴곡부 중심교각이 60도 인 경우에는 대상선박이 길이와 굴곡부의 중심교각에 따라 항로의 폭을 확장해야 할 것으로 분석되었다.