• Journal of Positioning, Navigation, and Timing
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• v.12 no.3
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• pp.289-294
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• 2023

As technologies such as cameras, Laser Imaging, Detection, and Ranging (LiDAR), and Global Navigation Satellite Systems (GNSS) become more sophisticated and common, their use in autonomous driving technologies is being explored in various fields. In the maritime area, technologies related to collision avoidance between ships are being developed to evaluate and avoid the risk of collision between ships by setting various scenarios. However, the position of each vessel used in the process of developing collision avoidance technology between vessels uses data obtained through GNSS, and may include a position error of 10 m or more depending on the situation. In this paper, a study on the dynamic safety navigation range including the positional inaccuracy of the ship is conducted. By combining the concept of the protection level obtained using GNSS raw data with a conventional safe navigation range, a safer navigation range can be calculated for dynamic navigation. The calculated range is verified using data obtained while sailing in an actual sea environment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.98-107
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• 2016

The purpose of this study is for Human error prevention to acquire Collision Risk Perception Index (CRPI) sensed by the Officer Of the Watch (OOW) when the approaching distances are reduced in six types of ship encountering situations (Head on, $045^{\circ}$, $090^{\circ}$, $135^{\circ}$, Overtaking, Overtaken) between own ship and a target ship and then to predict CRPI fitting coefficients with polynomials in the curve-fitting process. CRPI acquisition experiments are carried out on two coast-guard ships and with the total of 30 crew members. Analysing results shows that CRPI data have goodness of fit to the six types of encountering situation. Futhermore, the One-Way ANOVA results show that CRPI has a negative affect to the OOW's age, career and license grade as the approaching distances is reduced. The availability of CRPI curve fitting with 3 degrees of polynomial was testified through the RMSE as 1.19 to Head on, 0.87 to $045^{\circ}$, 0.81 to $090^{\circ}$, 0.71 to $135^{\circ}$, 1.29 to Overtaking and 0.87 to Overtaken.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.642-648
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• 2019

Vessels sail according to the COLREG to prevent a collision. However, it is difficult to apply COLREG under special situation as heavy traffic, at this time personal skills of the operator are required. In this case, traffic control is required through the maritime traffic monitoring system. Therefore, maritime traffic management is globally implemented by VTS. In this system, VTS of icer uses the VTS system to assess risks and recommends possible safety operation to vessels with radio systems. This study considers that the risk analysis method with AI (Artificial Intelligence) technology from the operator's aspect. In addition, the research explains the Maritime Traffic Safety Monitoring System, Including AR (Augmented Reality) technology to increase vessel control efficiency. This system is able to predict hazards and risk priorities, and it leads to sequential elimination of dangerous situations. Especially, the hazard situations can be analyzed from operator's perspective of each vessel instead of the VTS officer's aspect, which is more practical than the conventional method. Furthermore, the result of analysis enables to comprehend quantitative hazardous areas and support recommended routes to avoid a collision. As a result, I firmly believe that the system will support to prevent a collision in complex traffic waters. In particular, it could be adopted as a collision prevention system for Maritime Autonomous Surface Ship, which occupies a significant proportion in Maritime 4th industrial revolution.

• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.105-111
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• 2016

In ports of Korea, the marine traffic flow is congested due to a large number of vessels coming in and going out. In order to improve the safety and efficiency of these vesse's movement, South Korea is operating with a Vessel Traffic System, which is monitoring its flow 24-7. However despite these efforts of the VTS (Vessel Traffic System) officers, marine accidents are occurring continuously in their control area. VTS Officers are controlling subjectively based on their experience due to no VTS control guideline of dangerous situation among vessels. On this paper, we listened to Busan VHF channel for 3days and analyzed the message. With collision risk model, We analyzed a moment of risk which officers advise or recommend to vessel in encounter situation, VTSO's career, and day&night.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.72-77
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• 2010

The Incheon Bridge, which was opened to the traffic in October 2009, is an 18.4 km long sea-crossing bridge connecting the Incheon International Airport with the expressway networks around the Seoul metropolitan area by way of Songdo District of Incheon City. This bridge is an integration of several special featured bridges and the major part of the bridge consists of cable-stayed spans. This marine cable-stayed bridge has a main span of 800 m wide to cross the vessel navigation channel in and out of the Incheon Port. In waterways where ship collision is anticipated, bridges shall be designed to resist ship impact forces, and/or, adequately protected by ship impact protection (SIP) systems. For the Incheon Bridge, large diameter circular dolphins as SIP were made at 44 locations of the both side of the main span around the piers of the cable-stayed bridge span. This world's largest dolphin-type SIP system protects the bridge against the collision with 100,000 DWT tanker navigating the channel with speed of 10 knots. Diameter of the dolphin is up to 25 m. Vessel collision risk was assessed by probability based analysis with AASHTO Method-II. The annual frequency of bridge collapse through the risk analysis for 71,370 cases of the impact scenario was less than $0.5{\times}10^{-4}$ and satisfies design requirements. The dolphin is the circular sheet pile structure filled with crushed rock and closed at the top with a robust concrete cap. The structural design was performed with numerical analyses of which constitutional model was verified by the physical model experiment using the geo-centrifugal testing equipment. 3D non-linear finite element models were used to analyze the structural response and energy-dissipating capability of dolphins which were deeply embedded in the seabed. The dolphin structure secures external stability and internal stability for ordinary loads such as wave and current pressure. Considering failure mechanism, stability assessment was performed for the strength limit state and service limit state of the dolphins. The friction angle of the crushed stone as a filling material was reduced to $38^{\circ}$ considering the possibility of contracting behavior as the impact.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.594-600
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• 2020

The identification of the risk of collision between ships and objects is vital for achieving navigation safety. The purpose of this study is to analyze the phenomenon of ship domain invasion by breakwaters when ships pass between breakwaters. A method for evaluating the domain-invaded area under the conditions of the breakwater was developed. Next, experimental data were obtained and processed using the Automatic Identification System (AIS) of ships sailing near the breakwater at Busan Port to establish a ship domain that could be formed between the breakwaters. The ship domain was then constructed using Fujii's domain. Finally, the phenomenon in which the constructed ship domain was invaded by the breakwater was analyzed. Based on the experimental results, the domain of the ship invaded by the breakwater was identified.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.67-73
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• 2021

The purpose of this study is to obtain a safe area for a passing vessel between anchored vessels by developing a model to predict the collision risk, frequent collisions occur between the anchored vessel and the passing vessel through the anchorage. For this, this study selected the southern anchorage of Busan port, which is the largest harbor in Korea, as the target area and extracted and analyzed VTS (Vessel Traffic Service) data during the period in which anchored vessels were the most waited. The ratio of D/L for each bearing was obtained to determine the safe distance (D) passes based on the length (L) of the passing vessel between anchored vessels. Based on the average domain of the D/L ratio distribution, the percentage of anchored vessels within the scope of the pre-studied ship's domain was analyzed to obtain a domain reflecting the degree of risk of VTSOs. Further research will evaluate and analyze the collision risk of a passing vessel using Domain-watch, the minimum safe distance between anchored vessels, and the safe domain of a passing vessel through anchorage, to develop a model for VTS to manage anchorages more efficiently and safely.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.1
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• pp.25-34
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• 1999

The Steering and Sailing Rules of International Regulation for Preventing Collisions at Sea now in use direct actions to avoid collision when two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision. But these rules do not refer to the minimum relative distances and safety relative distances between two vessels when they should take such actions.In this paper the ship's collision avoiding actions being analyzed from a viewpoint of ship motions, the mathematical formulas to calculate such relative distances necessary for taking actions to avoid collision were worked out. The values of maneuvering indices being figured out through experiments of 20 actual ships of small, medium, large and mammoth size and applied to calculating formulas, the minimum relative distances and safety relative distances were calculated. The main results were as follows. 1. It was confirmed that the criterion elements for collision avoiding actions in head-on situation of two vessels shall be the minimum relative distances and safety relative distances between them. 2. On the assumption that two vessels same in size and condition were approaching each other in head-on situation, the minimum relative distance of small vessel(GT : 160~650tons) was found to be about 4.7 times her own length, and those of medium (GT:2,300~4,500tons),large(GT:15,000~62,000tons) and mommoth (GT:91,000~194,000tons) vessels were found to be about 5.2 times, about 5.2 times and about 6.1 times their own lengths respectively. 3. On the assumption that two vessels same in size and condition were approaching each other in head-on situation, the safe relative distance of small vessel (GT : 160~650tons) was found to be about 6.8 times her own length, and those of medium (GT : 2,300~4,500tons), large (GT: 15,000~62,000tons) and mammoth (GT : 91,000~194,000tons) vessels were found to be about 9.0 times, about 6.3 times, and about 8.0 times their own lengths respectively. 4. It is considered to be helpful for the safety of ship handling that the sufficient safe relative distances for every vessels shall be more than about 12~14 times which are 2 times minimum relative distance, their own length on above assumption.

• Journal of Navigation and Port Research
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• v.42 no.1
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• pp.25-30
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• 2018

This study was carried out to analyze the risk attitude based on situation awareness of the Vessel Traffic Service Operator (VTSO) on the risk of collision between vessels during the monitoring of vessel traffic through the use of the VTS system. In general, when two vessels are in the close quarters situation, we analyzed the degree of risk of collision from the subjective viewpoint of the VTSOs through an administered survey. Chiefly, we analyzed the risk attitudes of each VTSO in the close quarters situation, by comparing it with the calculated value by the CoRi, which is the ship collision risk model from the VTSO's viewpoint. As a result, it was confirmed that more than 40% of the total VTSO was noted as being in a weak risk aversion type of category. Through a review of the results of analyzing the risk attitude of VTSO according to gender, age, VTS career, VTS center position, accident experience, and boarded career, it was found that there was a significant difference in the VTS career, VTS center position and accident experience. In addition, a regression model that is able to further explain the risk attitude of VTSO was derived as a factor that confirmed the significant difference and applied to CoRi to predict the collision risk according to the individual VTSO to be used as a fundamental information gathering tool for providing more accurate and safe VTS service at sea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.2
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• pp.152-161
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• 2019

This research carried out a study on the job characteristics of the skipper of the coastal composite fishing vessels in order to find a way to prevent the ship collision caused by the highest human error among the marine casualty of fishing boats. Video observation was used as the research method in which six CCD cameras were installed on the vessel to collect image data and data extracted from the image were analyzed to derive the results of the functional activity of skipper according to the fishing operation process of experimental fishing vessel. The results are as follows. The working process of the experimental fishing vessel consisted of navigation for fishing ground, setting line, waiting for hauling line, hauling line and navigation to homeport. In these processes, the skipper was performing watchkeeping in the wheelhouse in which he carried out a single task, a dual task that performed two tasks simultaneously, and a triple task that performed two or more tasks simultaneously. In addition, one of the risk factors causing the collision was a no watchkeeping in the wheelhouse for navigating for fishing ground, waiting for hauling line, and hauling line at 25.4%, 64.6% and 0.3%, respectively among the marine casualty while drowsiness caused 1.2% of the marine casualty in navigating for fishing ground. Concurrent tasks that simultaneously perform two or more tasks that can overlook any other important duties while carrying out watchkeeping in the wheelhouse include 51.3% of navigation for fishing ground, 81.9% of setting line, 19.0% of waiting for hauling line, 87.9% of hauling, and 88.7% of navigation to homeport. The above concurrent tasks yielded an average of 66.1%. Experimental fishing vessels are required to focus on ship handling operations related to fishery operations, and the skipper is assigned more activities and attention to fishery related tasks. Therefore, it is considered desirable to build a collision prevention system that is appropriate to the characteristics of the skipper's work, escaping from transferring the responsibility of ship collision to the skipper completely.