• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.91-97
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• 2021

Marine accidents caused by ships have brought about economic and social losses as well as human casualties. Most of these accidents are caused by small and medium-sized ships and are due to their poor conditions and insufficient equipment compared with larger vessels. Measures are quickly needed to improve the conditions. This paper discusses a video-integrated collision prediction and fall detection system to support the safe navigation of small- and medium-sized ships. The system predicts the collision of ships and detects falls by crew members using the CCTV, displays the analyzed integrated information using automatic identification system (AIS) messages, and provides alerts for the risks identified. The design consists of an object recognition algorithm, interface module, integrated display module, collision prediction and fall detection module, and an alarm management module. For the basic research, we implemented a deep learning algorithm to recognize the ship and crew from images, and an interface module to manage messages from AIS. To verify the implemented algorithm, we conducted tests using 120 images. Object recognition performance is calculated as mAP by comparing the pre-defined object with the object recognized through the algorithms. As results, the object recognition performance of the ship and the crew were approximately 50.44 mAP and 46.76 mAP each. The interface module showed that messages from the installed AIS were accurately converted according to the international standard. Therefore, we implemented an object recognition algorithm and interface module in the designed collision prediction and fall detection system and validated their usability with testing.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.241-257
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• 2020

The rapid proliferation of oil/gas drilling and wind turbine installations with jack-up rig-formed structures increases structural safety requirements, due to the greater risks of operational collisions during use of these structures. Therefore, current industrial practices and regulations have tended to increase the required accidental collision design loads (impact energies) for jack-up rigs. However, the existing simplified design approach tends to be limited to the design and prediction of local members due to the difficulty in applying the increased uniform impact energy to a brace member without regard for the member's position. It is therefore necessary to define accidental load estimation in terms of a reasonable collision scenario and its application to the structural response analysis. We found by a collision probabilistic approach that the kinetic energy ranged from a minimum of 9 MJ to a maximum 1049 MJ. Only 6% of these values are less than the 35 MJ recommendation of DNV-GL (2013). This study assumed and applied a representative design load of 196.2 MN for an impact load of 20,000 tons. Based on this design load, the detailed design of a leg structure was numerically verified via an FE analysis comprising three categories: linear analysis, buckling analysis and progressive collapse analysis. Based on the numerical results from this analysis, it was possible to predict the collapse mode and position of each member in relation to the collision load. This study provided a collision strength assessment between attendant vessels and a jack-up rig based on probabilistic collision scenarios and nonlinear structural analysis. The numerical results of this study also afforded reasonable evaluation criteria and specific evaluation procedures.

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.377-383
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• 2019

Naval ships that are navigating always have the possibility of colliding, but there is no clear maneuvering procedure for collision avoidance, and there is a tendency to depend entirely on the intuitive judgment of the Officer Of Watch (OOW). In this study, we conducted a questionnaire survey when and how to avoid collision for the OOW in a Constant Bearing, Decreasing Range (CBDR) situation wherein the naval ships encountered obstacles. Using the results of the questionnaire survey, we analyzed the CBDR situation of encountering obstacles, and how to avoid collision in day/night. The most difficult to maneuver areas were Pyeongtaek, Mokpo, and occurred mainly in narrow channels. The frequency appeared on average about once every four hours, and there were more of a large number of ships encountering situations than the 1:1 situation. The method of check of collision course confirmation was more reliable with the eye confirmation results, and priority was given to distance at closest point of approach (DCPA) and time at closest point of approach (TCPA). There was not a difference in DCPA between the give-way ship and stand-on ship, but a difference between day and night. Also, most navigators prefer to use maneuvering & shifting when avoiding collisions, and steering is 10-15°, shifting ±5knots, and the drift course was direction added stern of the obstacles to the direction of it. These results will facilitate in providing officers with standards for collision avoidance, and also apply to the development of AI and big data based unmanned ship collision avoidance algorithms.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2001.10a
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• pp.114-119
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• 2001

Based on tole investigation on mariner’s behaviors in collision avoidance, actuality of collision avoidance at sea and the research on the uncertainty of collision avoidance behaviors adopted by two encounter vessels, and for the purpose to reduce the no-coordination action of collision avoidance between two encounter vessels, and on the base of different encounter situation in international convention for preventing collisions at sea, the concept of action situation between tee encounter vessels is proposed, and the directions for every encounter vessel to adopt course alteration to avoid collision are explained in different action situation. The mechanism of avoidance and reduction of no-coordination is established in intelligent collision avoidance system, and it is important id research on intelligent collision avoidance system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.745-748
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• 2001

Digital-ship is the next-generation ship with an one-man bridge system which consists of INS(Intelligent Navigation System), AIS(Automatic Identification System), and IMIT(Integrated Maritime Information Technology). INS implements the functions is related of the ship's navigation, and supports in the digital GIS environments optimal route planning, stranding and a collision avoidance among the ship, an economic navigation, and an integrated control of ship's engine. AIS prevents the ship's collision by means of transmitting periodically the own ship's information to the other ship or the shore control center. IMIT systems supports the integrated fiat-form in ships, the communication between a ship and a control center of the land using the INMARSAT, OrbComm, Ocean Observation Satellite, and etc. The satellite communication in ships can monitor the ship at an earth control renter. This paper deals with the method for system implementation of digital-ship and the detailed sub-system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.169-176
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• 2005

An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted annual frequency of bridge collapse, AF, from the ship collision risk assessment is compared to an acceptance criterion. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed AF is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The distribution of the AF acceptance criterion among the exposed piers is generally based on the designer's judgment. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.246-257
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• 2020

According to the statistics of KMST (2010~2019), 68.5% of marine casualties have been occurred in fishing boats in the last 10 years. Although the incidence rate of annual average per ship is 10.4% for merchant ships and 2.3% for fishing boats, it is necessary to first reduce the marine casualties of fishing boats in order to reduce the occurrence of the whole marine casualty, considering that the number of registered fishing boats are 86.5% of the total. In this study, the top 10 fishing types with high occurring marine casualties in the past 10 years were selected using the statistics of KMST. Then, the causes of the marine casualties, focusing on the collision, were analyzed and counterplan were suggested. The biggest marine casualty that the top 10 fishing types have caused in the past 10 years was a collision, accounting for 71.7% of the total, and the rest were less than 10.0% each. Also, it was found that the biggest environment and cause of the collision were due to human factors such as poor look out or negligence of duty. Eventually, it was concluded that a reduction in the human factors for the causes basically, could lower the incidence of the marine casualties. Therefore, if the continuous and systematic correcting education of the attitude toward the ship operating of seafarers could conducted with the focus on the main human factors, the whole marine casualties will be expected to decrease gradually.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.8-14
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• 2020

According to the statistics provided by Korean Maritime Safety Tribunal for the year 2018, the majority of marine accidents in the past four years have occurred in fishing boats and small-sized boats. Negligent behavior resulting from not looking outside and non-compliance with navigation laws are the primary reasons behind ship collisions. Although safety education and training are reinforced to prevent such accidents, they still occur frequently. Hence, technical methods are continuously being developed to reduce ship collisions caused by human cause. The objective of this study is to reduce ship collisions by employing the WAVE communication system, which has short transmitting and receiving periods that can be incorporated for high-speed small-sized vessels. In this study, the suitability of the communication range was examined, and the appropriate range and timing for avoidance motion were accordingly selected, and a control algorithm based on the same was thereby designed. Consequently normal operation of the collision avoidance system was verified by connecting and simulating the proposed WAVE communication router-controller-steering equipment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1129-1139
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• 2022

Collision accidents happen frequently. The majority of ships involved in collisions in the coastal areas of Korea are middle and small size ships. The proportion of collision accidents is only 9% of all types of marine accidents; however, the number of casualties resulting from collisions is 34.4% of all human life damages. Generally, as reported by the people involved in these collisions, the navigation lights of the opponent ships were poor and invisible when the accident happened even though the weather and visibility were good. Furthermore, there are many insistences for poor navigation light conditions of the opponent ship in the bay or harbor. Therefore, it is necessary to analyze the present conditions and safety of navigation lights. Therefore, in this study, we examined the rules and books of navigation lights and compared it to that of other transportation systems, such as aircraft, trains, and road vehicles. Furthermore, we analyzed the current marine traf ic circumstances and ship collision accidents that happened in the past 5 years. Additionally, a questionnaire was prepared to gather the opinion of ship experts and secure the objectivity for improvement methods of navigation lights. Finally, methods to improve the navigation lights on ships were devised.

• Journal of Ocean Engineering and Technology
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• v.37 no.6
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• pp.247-255
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• 2023

Interference and collisions often occur in the loading process at shipyards. Existing simulation methods focus primarily on resource processes and schedules, and there is a lack of real-time reflection in the complex and highly variable loading process. This study aims to develop a spatial environment incorporating real-time product data, such as hulls, and confirms its effectiveness by simulating various construction scenarios. As a method, a near real-time spatial environment based on broadband laser scanning was established, with the situation of loading heavy cargo assumed when converting an existing ship into an LNG dual-fuel propulsion ship. A case study simulation of near-real-time cargo loading processes was then conducted using Unity 3D to confirm the interference and collision risks within the spatial environment. The results indicated that interference occurred in structures previously not identified in the design data, and a collision occurred during the loading object erection phase. The simulation confirmed that the identification of interference and collision risks during the erection phase highlights the need for a relocation or removal process of potential hazards before erection takes place. An improved erection simulation that integrates near real-time data could effectively prevent interference and collision risks.