• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3329-3350
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• 2017

Installing caching and computing facilities in mobile edge networks is a promising solution to cope with the challenging capacity and delay requirements imposed on future mobile communication systems. The problem of optimal facility placement in mobile edge networks has not been fully studied in the literature. This is a non-trivial problem because the mobile edge network has a unidirectional topology, making existing solutions inapplicable. This paper considers the problem of optimal placement of a fixed number of facilities in a mobile edge network with an arbitrary tree topology and an arbitrary demand distribution. A low-complexity sequential algorithm is proposed and proved to be convergent and optimal in some cases. The complexity of the algorithm is shown to be $O(H^2{\gamma})$, where H is the height of the tree and ${\gamma}$ is the number of facilities. Simulation results confirm that the proposed algorithm is effective in producing near-optimal solutions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.115-118
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• 2003

In this paper, we analysed the technical characteristics of power line communications interfering marine mobile services. The various radio services including marine mobile potentially affected by unwanted radiation from telecommunication networks as PLT, VDSL, ADSL, etc. The radio spectrum is unique resource. In particular, the frequency range below 30MHz has extremely favourable propagation conditions allowing economic long range as well as low power communication radio services. The paper were as follows to identify marine mobile service that are likely to be affected by PLC and evaluate the protection needs and to investigate methods of measuring the emissions from PLC.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.513-519
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• 2013

The fishing industry in Europe has faced environmental, economic, and social challenges. Since the early 2000s, a key tool in addressing these challenges has been information and communication technology (ICT), which has helped to modernize fishery systems in European Union (EU) countries. The ICT used in EU fisheries can be categorized broadly as 1) macro-technologies such as satellite and other remote sensing technologies in combination with geographical information systems, 2) micro-technologies adapted for fishing vessels such as echo sounders, ship navigation devices, and mobile communication devices to connect fishermen and consumers, and 3) onshore micro-technologies related to internet technology and mobile devices. The European Monitoring Center on Change has used ICT to effectively manage fisheries bio-resources. This use of ICT has contributed to the development of sustainable and competent fisheries in the 2000s, even though the knowledge-sharing practices involved are contrary to the long tradition of autonomy within the fishery industry.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.120-130
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• 2009

In recent years, many mobile wireless communication devices and applications have been deployed on the planet. The mobile multi-hop wireless network models appeared to provide means to access to networks where few infrastructure exists. However, the mobile multi-hop wireless networks have weaker points in attacks and intrusions than the wired and one-hop wireless networks. In this paper, the secure routing issues in most mobile multi-hop wireless network models are surveyed in depth. The state-of-the-art technologies and research activities are explained. Finally, the issues and technologies for the secure routing specific to a maritime network model are sufficiently discussed as conclusions.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1145-1152
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• 2010

Currently economical communication technologies are needed for high speed data exchange at sea. Wireless environments at sea require some special communication security solutions as well. In this paper, an augmented WiMAX MMR protocol is proposed as a solution of the broadband data communications and security at sea environments fundamentally with no base station.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.71-77
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• 2013

Smart work has been gaining more popularity recently. Smart work means that employees perform their works anytime and anywhere as utilizing the information and communication technology. It can be divided into four categories; the mobile office, the home office, the work-at-center and the tele-cooperation. Among them, the mobile office based on tablet personal computers(PCs) or smart phones, employees can exchange information with tablet PCs or smart phones via mobile radio communication networks and portable terminals. Smart devices such as tablet PCs and smart phones help to access intranet system for requests, approvals, information search whenever employees need. This mobile office system for real-time HSE managing can contribute to improve the productivity and work efficiency in a shipyard. In this study, the main goal is to design the specialized mobile application for the HSE management system on the shipbuilding industry. The mobile application including 10 functions is designed based on ooCBD(object-oriented Component Based Development) methodology.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.135-135
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• 2012

USN(Ubiquitous Sensor Network)을 이용한 실내 위치 인식 기술은 주요한 연구 분야이며 산업에 미치는 영향이 매우 크다. 좁은 복도 환경에서는 삼변측위를 이용하지 않고 이변측위만 이용하더라도 Mobile Node의 위치 측정이 가능하다. 하지만 이변측위를 이용할 경우 Reference Node 사이의 간격이 멀어 질수록 Mobile Node의 위치 정보 수신율이 떨어져 Mobile Node의 위치를 표시할 수 없게 된다. 따라서 본 연구에서는 관성센서 및 초음파 센서를 이용하여 위치 정보의 수신이 이루어지지 않는 상황에서도 Mobile Node의 위치를 표시할 수 있게 구성하고 실험을 통하여 검증하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.163-166
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• 2004

Integrated Ship-Shore Information System makes use of advanced technology of marine mobile communication and extends the computer network of shipping company to ship. This system conveniently accomplishes the information exchange between company and ship, guarantees navigation safety and improves commercial performance. The framework of integrated ship-shore information system and the analysis of its function are provided in this paper. Meanwhile, the idea based on the specification of J2EE to build this system is put forward and the relevant technology is demonstrated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.171-174
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• 2005

According as marine leisure industry has developed and the demand of leisure culture has increased rapidly, a desire about service which supply marine safety and connect marine information is enlarging. The performance of personal mobile device has improved and been evolved by composition terminal. So, it became possible that storage and expression of multimedia information as well as simple communication facility. Domestic wireless internet has given development strain to developer and contents Provider(CP) because of different platform. And this has become hindrance factor of wireless internet activation. But, recently, the use of WIPI(Wireless Internet Platform for Interoperability), the wireless internet standard platform, could use different wireless application programs and also guarantee the independency for hardware. We wish to develop contents of download form that supply geographic information of Electronic Navigational Chart(ENC) in the marine that is digitalized to carrying along terminal of WIPI base and various informations for marine leisure. For this, DB that offer ENC and additional information should be constructed. Also, we need server (CPS; Contents provider Server) that offer required contents. In this paper, we design web retrieval agent which store request information to database. When consumer required necessary information through personal mobile device, CPS can inform that by real time. So, we wish to develop agent component that parse informations in various World Wide Webs, and store to database.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2158-2165
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• 2023

Marine radioactivity monitoring is critical for taking immediate action in case of unexpected nuclear accidents at nuclear facilities located near coastal areas. Especially when the level of contamination is not predictable, mobile monitoring systems will be useful for wide-area ocean radiation survey and for determination of the level of radioactivity. Here, we used a silicon photomultiplier and a high-efficiency GAGG crystal to fabricate a compact, battery-powered gamma spectroscopy that can be used in an ocean environment. The developed spectroscopy has compact dimensions of 6.5 × 6.5× 8 cm³ and weighs 560 g. We used LoRa, a low-power wireless protocol for communication. Successful data transmission was achieved within 1.4 m water depth. The developed gamma spectroscopy was able to detect radioactivity from a ¹³⁷Cs point source (3.7 kBq) at a distance of 20 cm in water. Moreover, we demonstrated an unmanned radioactivity monitoring system in a real sea by combining unmanned surface vehicle with the developed gamma spectroscopy. A hidden ¹³⁷Cs source (3.07 MBq) was detected by the unmanned system at a distance of 3 m. After successfully testing the developed mobile spectroscopy in an ocean environment, we believe that our proposed system will be an effective solution for mobile real-time marine radioactivity monitoring.