• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.3
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• pp.22-27
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• 2012

In oceanic flight routes, HF radio and satellite data links have been used for air-to-ground communication, but these systems have long propagation delay and low data throughput. In this paper, we propose a reliable system to overcome the weakness of current HF radio and satellite communication systems for oceanic aeronautical flight routes. The proposed scheme uses only one aeronautical VHF channel in multi-hop oceanic communication environments and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. The proposed system improves performance on delay and throughput as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.15-22
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• 2013

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.405-411
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• 2020

Recently, studies on underwater communication, related to the development of underwater resources, disaster monitoring and defense, have been actively carried out. In the design of wireless communication systems, path loss is the most important information to derive a link budget that is required to guarantee communication reliability by calculating received power level for the given communication link. The underwater acoustic channel have different characteristics according to geographical location and relevant environmental factors such as water temperature, depth, wave height, algae, and turbidity. Subsequently, many research institutes aiming to develop underwater acoustic communication systems are researching actively on the underwater acoustic channels in various sea areas. In Korea, however, studies on the path loss of the acoustic channel are still insufficient. Therefore, in this study, the path loss of the acoustic channel are studied based on measurement data of the at-sea experiment conducted at Geohae-do, southern sea of Korea.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1237-1239
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• 2023

본 논문에서는 Linear Frequency Modulation(LFM)을 이용하여 실해역에서 실험을 진행하였다. LFM 이란 시간에 따라 주파수가 변화하는 Chirp 신호를 전송하는 통신 기법이며 성능 분석을 위해 대한민국의 한강, 서해, 남해에서 각각 실험을 진행하였다. LFM 신호의 중심 주파수는 34kHz 대역폭은 1kHz로 설정하여 실험을 진행하였으며 채널 환경 분석을 위한 5초 길이의 Tone 신호를 함께 송·수신 하였다. 실험 결과 세 곳의 실험 포인트 모두에서 송·수신 신호 간의 뚜렷한 상호상관 결과를 확인할 수 있었다.

• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.253-257
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• 2013

Mobile computers can process large amounts of data at high speeds, and it is feasible and easy to implement a remote monitoring system utilizing mobile computers. Because of their portability and convenience, these computers have been employed in various research areas to develop such monitoring systems. Existing monitoring system is a bit difficult to real time monitoring the scattered offshore facilities. So this paper compensate the existing system by using mobile computers such as a tablet PC-based monitoring system. Also, the scattered offshore facilities can be monitored in real-time through the tablet PC. The developed monitoring system is a fully Internet-based monitoring platform that enables one to monitor and control remote oceanic applications at any time and any place where it is possible to access the Internet. It can be applied to many oceanic applications as well as the unmanned systems and remote monitoring systems on land.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.1939-1946
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• 2008

The Oceanic ecosystem destruction caused by Water-Bloom, Jellyfish development, and Oil contamination in nation's waters becomes serious problem. For these reasons, the oceanic conditions are observed in air and on the water using helicopters and vessels. But, employing helicopters and vessels are limitted on a budget, and weather conditions. To overcome these problems, an unattended automated monitoring system not only gather all sorts of the oceanic condition in spite of bad weather, but save labor and oil costs. For each sensor connected in network and radiodetermination, location of sensors are verified in the tidal water to improve gathering informations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.365-370
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• 2016

Recently, There are increasing number of studies that apply multi-carrier method, a land mobile communication method, to underwater channel environment in order to enhance the performance of underwater communication. Therefore, in this paper, in order to design a new system with improved communication performance compared to the multi-carrier method in underwater communication, we present that the RS(Resource Spreading) FMT-OFDM system has a diversity and repetition effect from resource spreading. Moreover, we verify the performance of RS FMT-OFDM system and existing FMT-OFDM system through simulations after modeling communication channels and setting the system parameter based on the data measured from the real sea. Our result indicate that, compared to the existing FMT-OFDM system, there has been an improvement in communication performance by 12dB based on BER $10^{-3}$ we also discovered that communication performance improves as the resource spreading rate increases.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.11
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• pp.1434-1442
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• 2019

In this paper, the channel change was continuously measured for 24 hours from July 5, 2017 on the coast near Deokjeok-do, Incheon. The underwater channel has various channel environment characteristics as the change in the time axis and the change in the frequency axis occurs in real time, and the underwater communication performance decreases due to the multipath fading and the Doppler effect. Therefore, in this study, we performed the OFDM system performance analysis in the underwater channel environment by applying the repetitive transmission diversity scheme in the time and frequency domain to improve the communication performance in the real-world underwater communication environment. Using the collected data, we compared the channel environment in the time and frequency domain and analyzed the BER performance according to the pilot spacing and the number of repetitive transmissions in the time and frequency axis.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.2
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• pp.311-318
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• 2015

Red tide occurs every year in the coastal seas of the South Korea, This phenomena has become a national issue of environmental and economic damage. In this study, we analyzed a suitable conditions to occur the red tide by using oceanic and atmospheric data during 10 years, These factors were applied to predict the red tide occurrence from 2012 to 2014. As a result, in 2012 and 2013, it is able to alarm the red tide occurrence before 6~11 days. However, in compared to the normal year and 2014, the prediction of red tide occurrence were less accurate because of more precipitation, short sunshine duration, low temperature waters. Therefore, it is necessary to further investigate the impact of sunshine duration(Solar radiation) on red tide occurrence, it is more necessary to consider the comprehensive analysis using additional oceanic and atmospheric factors.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.71-79
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• 2009

The world-wide ship construction market is forecast that the considerable portion of shipbuilding and oceanic plant industry will be transferred consequently in China after 5 or 10 years. This point of view where the Korean ship construction industry seizes the initiative from the world-wide ship construction/oceanic field, we must cultivate technical power of base technology, and focus our interests on the development of core parts. In this study, our proprietary remotely operated valve actuator system with power line technology was developed to enhance the installation and commissioning process by our own technology. This paper describes the new design and functions of the remotely operated valve system for shipbuilding and offshore market especially for FPSO.