• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.867-874
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• 2021

The IoT (Internet of Things) technology is rapidly becoming an important consideration in many engineering fields in the current 4th industrial era. In recent years, the concepts of digital shipbuilding and smart factories have been adopted as trends in shipyards. However, there is active interest in research on implementing autonomous driving in autonomous vehicles and airplanes, which is currently available in commercial form in a limited capacity. The present study is regarding the path-tracking performance of a boat to accomplish an autonomous driving mission using a flight controller (FC) and real-time kinematic (RTK) global positioning system (GPS) based on an open-source Ardupilot; an actual sea test is also performed using this system on a calm lake. The boat's mission is to evaluate the maneuverability of the self-driving process to a specific point and returning to the home position. For a given speed, the difference between the preset mission trajectory and actual operational trajectory was analyzed, and a series of studies were conducted on the applicability of the system to ships. In addition, the movements and maneuverability of the OmniX-type hull with four propellers were investigated, and the driving path-tracking performance was observed to increase by a maximum of 48%.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.832-838
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• 2021

Recently, reports of marine accidents of small fishing vessels less than 10 tons have been increasing. In this study, the characteristics of the motion response in regular waves were analyzed using computations for these ships. Small vessels less than 10 tons are classified by size and used for marine accident investigations. Therefore, the motion response analysis was performed on three small fishing vessels of different sizes. In the case of the head sea, it was confirmed that as the speed of the vessel increased in the long wavelength region, the motion responses of heave and pitch became large. The motion response of the smallest 3-ton fishing vessel was greater than that of the other sizes of fishing vessels. The maximum value of the roll motion shifted to the long wavelength region as the speed gradually increased in the bow sea, regardless of the size of the ship. In all the three small fishing vessels, it was found that the roll motion was the greatest at 15 knots, the highest speed in both bow and beam seas. When sailing in the head sea and bow sea conditions, lowering the speed is one of the effective approaches to reduce the effects of the vertical and lateral plane motions. The roll motion caused by the beam wave showed a tendency to increase rapidly only at a specific wavelength regardless of the speed and the size of the vessel. It was confirmed that the roll motion was significantly reduced with forward speed in the stern wave compared to the bow wave. As there is a specific region where the maximum value of the hull motion response appears depending on the size and speed of the ship, an operation method that can minimize the effect of this motion should be considered and implemented.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.930-938
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• 2018

Underwater noise radiated from submarines is directly related to the probability of being detected by the sonar of an enemy vessel. Therefore, minimizing the noise of a submarine is essential for improving survival outcomes. For modern submarines, as the speed and size of a submarine increase and noise reduction technology is developed, interest in flow noise around the hull has been increasing. In this study, a noise analysis technique was developed to predict flow noise generated around a submarine shape considering the free surface effect. When a submarine is operated near a free surface, turbulence-induced noise due to the turbulence of the flow and bubble noise from breaking waves arise. First, to analyze the flow around a submarine, VOF-based incompressible two-phase flow analysis was performed to derive flow field data and the shape of the free surface around the submarine. Turbulence-induced noise was analyzed by applying permeable FW-H, which is an acoustic analogy technique. Bubble noise was derived through a noise model for breaking waves based on the turbulent kinetic energy distribution results obtained from the CFD results. The analysis method developed was verified by comparison with experimental results for a submarine model measured in a Large Cavitation Tunnel (LCT).

• Journal of Navigation and Port Research
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• v.48 no.4
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• pp.267-273
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• 2024

Bridge lanterns are installed on bridges or piers to signal the presence of these structures on navigational routes and navigable waters, and they fall under the category of light wave signals in Aids to Navigation. In Korea, medium to large bridges installed over major rivers and seas are equipped with bridge lanterns, which are necessary for routes frequented by ships and require periodic inspections on a monthly or multi-month basis. However, most bridge lanterns are mounted externally on bridge railings as fixed or manual rotary supports, posing a high risk of fatal falls during inspections. Furthermore, high -traffic bridges demand quick maintenance works due to complaints about traffic disruption, thus increasing work hazards. Consequently, this study introduced a tailored automatic bridge lantern support concept based on different types of bridge lantern installations, aiming for safe and rapid inspections. Additionally, the study sought to achieve full automation of the bridge lighting system by integrating it with a management program for monitoring and controlling bridge lanterns, utilizing both wired and wireless communication technologies. These findings provide foundational design data for new and refurbished bridges that will be installed in the future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.582-588
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• 2014

IMO and IALA have undertaken projects that GMDSS Modernization and E-navigation, which refer to "Future digital communications systems" for a more efficient transmission of voice and data communications in the VHF maritime mobile service. ITU has also resolved in WRC-07 Resolution 357 to study the use of spectrum-efficient technologies in order to provide for the operation of ship and port security and maritime safety systems. IALA and ITU WP5B have coordinated for the technical developments and the spectrum issues. Recommendation ITU-R M.1842-1 has approved by WP5B meeting. This revision provides a wideband data service both 50kHz and 100kHz in the VHF maritime mobile service. This paper has studied E-navigation, its needs for data exchange that includes explanations of the current methods for transmitting data by VHF that based in land mobile radio service. A further technologies trend is estimated for Recommendation ITU-R M.1842-1, that is based on the land mobile radio standards with some tailored to fit the needs of the maritime mobile service.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.8-14
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• 2019

Bird-strike is one of the most important design factors for safety in the aviation industry. Bird-strikes have been the cause of significant damage to aircraft and rotorcraft structures and the loss of life. This study used DYTRAN software to simulate the transient response of an Euler-Lagrangian composite helicopter blade that has been impacted by a bird. The Arbitrary Lagrangian Eulerian (ALE) method and a suitable equation of state were applied to model the bird. ALE was applied to the bird-strike analysis due to the large difference between the properties of the blade and bird. The debris of the bird was assumed to be a fluid and applied as Euler elements after the collision. Through the analysis of bird impacts, the leading-edge of the rotor blade (50.8 mm) was used to identify a positive margin of 1.18 based on the TSAI-FILL criteria. The results are assessed to be sufficiently reliable and may be evaluated to replace tests with various analysis conditions. The structural stability of the rotor blade could be assessed by applying various load conditions and different modeling methods in the future.

• The Korean Journal of Air & Space Law and Policy
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• v.34 no.1
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• pp.159-201
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• 2019

Along with Annex 14 Volume I establishment in 1951 and the set-up of restriction surface around the runway, aeronautical technique and navigation performance achieved dazzling growth, and the safety and precision of navigation greatly improved. However, restrictions on surrounding obstacles are still valid for safe operation of an aircraft. Standards and criteria for securing safety of aircraft operating around and on airport is stated in Annex 11 Air Traffic Services and Annex 14 Aerodrome etc. In particular, Annex 14 Volume I presents the criteria for limiting obstacles around an airport, such as natural obstacles such as trees, mountains and hills to prevent collisions between aircraft and ground obstacles, and artificial obstacles such as buildings and structures. On the other hand, Annex 14 Volume I, in the application of the obstacles limitation surfaces, apply the exception criteria, as it may not be possible to remove obstacles that violate the criteria if the aeronautical study determines that they do not impair the safety and regularity of aircraft operation. Aeronautical study has been applied and implemented in various countries including United States, Canada and Europe etc. accordingly, Korea established and amended some provisions of the Enforcement rules of the Aviation Act and established the Aeronautical study guidelines to approve exceptions. However, because ICAO does not provide specific guidelines on procedures and methods of Aeronautical study, countries conducting aeronautical study have established and applied their own procedures and methods. Reflecting this realistic situation, at the 12th World Navigation Conference and at the 38th General Assembly, the contracting States demanded a reexamination of the criteria for current obstacle limitation surfaces and methods of aeronautical study, and the ICAO dedicated a team of experts to prepare new standard. This study, in line with the movement of international change in obstacle limitation surface and aeronautical study, aims to compare and analyze current domestic and external standards on obstacle limitation and height limits, while looking at methods, procedure and systems for aeronautical study. In addition, expecting that aeronautical study will be used realistically and universally in assessing the impact of obstacles, we would recommend the institutional improvement of the aeronautical study along with the development of quantitative analysis methods using the navigation data in the current aeronautical study.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1195-1202
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• 2016

Recently, a lot of studies that applying the big data technology to various fields, are progressing actively. In the maritime domain, the big data is the meaningful information which makes and gathers by the navigation and communication equipment from the many ships on the ocean. Also, importance of the maritime safety is emphasized, because maritime accidents are rising with increasing of maritime traffic. To support prevention of maritime accidents, in this paper, we developed a vessel traffic display and statistic system based on AIS messages from the many vessels of maritime. Also, to verify the developed system, we conducted tests for vessel track display function and vessel traffic statistic function based on two test scenarios. Therefore, we verified the effectiveness of the developed system for vessel tracks display, abnormal navigation patterns, checking failure of AIS equipments and maritime traffic statistic analyses.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.962-968
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• 2013

Problem of greenhouse gases associated with global warming and the world rise in fuel oil prices due to the depletion of fossil fuel has attracted attention. For this reason, maritime transport business, has shown interest in green-ship technology to reduce the consumption of fuel and reduce greenhouse gas for environmental protection. Power system of the ship is one of the most important factors for safe operation. Therefore, at design of ship power system, most of existing vessel used comparative large capacity generator in order to respond peak load such as bow thruster, crane and etc. In the navigation of ship, marine generators most would be operated at low load operation. In the low load operation of the generation rate of 50% or less, the operation efficiency of the generator it deteriorated, to consume more fuel oil. It also, it means that adversely effect the life of the generator. In this paper, studied how to apply for a secondary battery in container ship that relatively frequent arrival and departure in port. As a result, in order to apply the secondary battery to increase the operating efficiency of the generator during the voyage, it was confirmed that it is possible to reduce fuel consumption.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.3
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• pp.1-9
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• 2019

In the recent marine sector, the development and standardization regarding S-100, which is the universal hydrographical data model standard for development of marine space information, was progressed, and for the effectiveness of marine chart production work and the multi-purpose use of water level data in S-100, S-102(Bathymetric Surface grid) standard development and various studies of BAG formats combined with water level and uncertainty, property information is being progressed. Since the water level information that is important in the operation of the ship is provided based on S-102, the calibration method of the location information when producing S-102 is an important factor in deciding the water level. In this study, the hydrographical surveying was conducted by piloting the standardized method for the production of S-102 in Korea, and have compared the accuracy of water level information according to the GNSS post treatment calibration method. As a result of comparing the water level in 2 places in the rocky terrain of the study area, the northern water level of Namu-do was shown as DL 0.79~0.83m, the eastern water level of Daeho-do was DL 12.63~12.91m, and the horizontal position errors of the intermittent sunshine water level were confirmed to be within 1m. As a result, the intermittent sunshine water level according to the location calibration method when producing the BAG was confirmed that it was in the available range for a ship's safe voyage. However, the accuracy verification for the location of the ship when conducting hydrographical surveying was judged that there is a need for a various additional study about regional characteristics and environment factor.