• Korean Journal of Remote Sensing
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• v.13 no.2
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• pp.133-150
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• 1997

The purpose of this paper is to develop an algorithm of classification and interpretation of seafloor based on side scan sonar data. The algorithm consists of mosaicking of sonar data using navigation data, correction and compensation of the acouctic amplitude data considering the charateristics of the side scan sonar system, and segmentation of the seafloor using digital image processing techniques. The correction and compensation process is essential because there is usually difference in acoustic amplitudes from the same distance of the port-side and the starboard-side and the amplitudes become attenuated as the distance is increasing. In this paper, proposed is an algorithm of compensating the side scan sonar data, and its result is compared with the mosaicking result without any compensation. The algorithm considers the amplitude characteristics according to the tow-fish's depth as well as the attenuation trend of the side scan sonar along the beam positions. This paper also proposes an image segmentation algorithm based on the texture, where the criterion is the maximum occurence related with gray level. The preliminary experiment has been carried out with the side scan sonar data and its result is demonstrated.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.731-738
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• 2017

Twin-hulls frequently incur structural damage at connecting members between the hull and deck induced by pitching motions during voyages. so, reasonable reinforcement is necessary around vulnerable spots such as corner knuckle, the chine bottom and inner hull. Since guidelines for structural design are not clear, engineers often respond by reinforcing plate thickness, changing stiffener sizes and reducing frame spacing, etc. These members constitute about 85 % of the longitudinal dimensions of the ship, so it is necessary to locally reinforce certain points to minimize weight stress, and also solve construction cost problems while securing the freeboard margin. Therefore, we developed a new program by analyzing the structural design procedures for the twin car-ferries based on Korean Register of Shipping (KR) High Speed Craft Rules, identifying items that need to be added. In order to ensure the reliability of buckling estimations for procedures and design programs, we conducted a comparative study with other standards and confirmed that differences were minimal.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.445-450
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• 2018

AIS is the most important navigation equipment for the identification of other ships, etc. However, the AIS overload problem has been raised recently due to an increase in AIS equipped vessels. The government is planning to introduce the wireless LTE network at 100 km offshore as part of the SMART-Navigation project. Continuous development and dissemination of the services available through such platforms will be necessary to achieve major goals such as marine accident prevention and environmental protection. In this study, we applied a WAVE communication system, which could be the basis for the development of such services. As a result, reliable data transmission was confirmed for a range of communication of approx. 5 miles, although the service was limited to 1 km in road traffic. Therefore, it is expected that WAVE communication technology will be used to prevent marine accidents through such efforts as collision avoidance and the transfer of marine safety information between ships.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.54-61
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• 2001

It is expected that ISO issue a standard method for sea trial and the correction of data taken during speed trial. One of the major reason for this effort(or trend) is to get reliable and accurate sea trial measurement. With the same philosophy, SHI(Samsung Heavy Industries) developed a nautical signal integrated unit in 1996. Two years after this, SHI developed a software that enable the user to analyze the sea trial measurement on-board. After a series of stationary and performance tests, KR has issued a certificate for international application of the software. We have been utilizing this program for the measurement and analysis of sea trial of more than 70 ships built in SHI shipyard. However, one critical defect of the software has been that it can be applied only for single shaft vessels. In this short paper, we would like to introduce a new version of the software which can be used for both single and multi thruster vessels. This paper deals with the introduction, test method and some of the test result.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.390-396
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• 2021

In this research, design and fabrication of marine repeater capable to extend communication coverage in monitoring system of fishing gear automatic identification, which is one of implementation method of the real-name electric fishing gear system declared by Ministry of Oceans and Fisheries in 2016, is reported. The proposed marine repeater is fabricated in a form of RF repeater with interference cancellation system (ICS), which can cancel the oscillation due to feedback signal between service antenna and link antenna. In design process, we secure the isolation of 30 dB between service antenna and link antenna. It is confirmed that when the level of feedback signal into repeater input be lower of 15 dB than repeater gain, error vector magnitude due to oscillation can be lower than the performance criterion of 6%, from the test verification. It is expected that the service coverage will be extended by applying the developed marine ICS RF repeater into marine IoT network including monitoring system of fishing gear automatic identification.

• Journal of IKEEE
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• v.25 no.3
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• pp.556-564
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• 2021

This paper presents trends of safety improvement technologies for an electric propulsion system of eco-friendly ships. As an effort to reduce a green house effect, demands for eco-friendly ships have been increased. An energy storage system (ESS) is one of key systems in an eco-friendly ship and a lithium-ion battery generally used in an ESS system due to its high power density and efficiency. However, a lithium-ion battery is considered as one of reasons for ESS fire hazard. Since a fire extinguishing facility is especially limited in the ocean, safety issue in an eco-friendly ship is important. In this paper, recent safety improvement technologies for traction motors, ESS batteries and structures for eco-friendly ships are presented.

• The Journal of shipping and logistics
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• v.34 no.4
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• pp.583-613
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• 2018

This study analyse the safe port warranty undertaking for shipowner of time charterer with the Ocean Victory Case. Litigation ensued between those in the charterparty chain. When the hull insurer, Gard, took an assignment of the rights of the vessel's owners and demise charterers in a claim against the time charterers that the vessel had been ordered by them to an unsafe port in breach of the charter. Although the claim succeeded, the Court of Appeal overturned the decision. The Supreme Court delivered its judgment on May 10, 2017, dealing with three important issues, safe port, joint insurance, and limitation of liability. Especially on the safe port issue, the court held that the port was not unsafe within the meaning of the safe port undertaking so the charterers were not in breach of it. The conditions in the port amounted to an abnormal occurrence as that expression is understood.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.3
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• pp.146-157
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• 2019

Recently, the importance of highly accurate bathymetric data is greatly emphasized by the increased use of the ocean numerical models and research results in major areas such as ocean forecasting and natural disaster. There are domestic bathymetric data mainly used in ocean numerical models of Choi et al.(2002) and Seo (2008), but the production year is old and the data was created on the basis of nautical charts. Nautical charts are made for the purpose of navigation and based on the minimum depth from bathymetric data, so there is a limitation to reproduce the actual submarine topography. Korea Hydrographic and Oceanographic Agency (KHOA) produces nautical charts every year through continuous bathymetric survey, but no bathymetric data for numerical models have been produced. In this study, using the raw bathymetric survey data, we built an exclusive bathymetric dataset (BADA Ver.1) for ocean numerical models and compared it with published bathymetric data.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.665-669
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• 2018

In this paper, we design an antenna for LTE / Wi-Fi communication that operates in 2.65 GHz and 5 GHz band for small-sized broadband communication antenna that can be used in the sea. Microstrip patch antennas were chosen to improve the bandwidth. The slot width, length, and transmission line width were calculated using the theoretical formula for each step. In addition, we designed a microstrip antenna using CST Microwave Studio 2014 program that can design 3D. Simulation results show that the reflection lossis -12.712 dB at 2.65 GHz and -16.583 dB at 5 GHz. The gain was 1.738 dBi at 2.65 GHz and 3.284 dBi at 5 GHz. In this paper, we propose a dual-band antenna for LTE / Wi-Fi, which can be used in maritime environments, which is worse than terrestrial communication, because of differences in communication speed and communication stability compared with those used on land.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.507-513
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• 2018

The maritime autonomous surface ship is automatically collects and manages various information necessary for the operation to minimize human intervention and safely perform the mission assigned to the ship. And the ship may autonomously operate the partial or entire route to the destination determined by the ship himself. This ship navigation technology allows partially remote control the ship to be operated if necessary. The maritime autonomous surface ship (MASS) should collect and manage signals of various navigation communication equipments and engines mounted on the ship for safe operation. This requires a common platform technology. In this paper, we propose a common platform that is the core of smart ship implementation. Territorial authorities and ships are connected by satellite or terrestrial communication. In such a communication environment, information is exchanged smoothly in real time. This allows the onshore authorities to monitor ships and provide remote control to enable safe vessel navigation at sea.