• Journal of Navigation and Port Research
• /
• v.36 no.4
• /
• pp.279-284
• /
• 2012

This study aims to identify the degree of safety when mariners take their actions in several different situations. We have carried out many experiments to observe mariners' behavior and then measured the safety level based on their actions to avoid dangerous situations of ships collision. One of the most important actions that mariners have to take, either as their daily routine or when they are in a collision situation and then want to avoid that situation is the lookout. In this paper, behaviors on the lookout have been defined as a standard sequence of three steps which are "time of first detection", "time of recognition as risky vessel" and "time of starting avoiding action", and the suitability and applicability of the definition have been shown. And also we propose the risk assessment on ships collision and the recommendation for reducing ships collision at sea. Some analyzing results and the application of the results are reported. By combining these knowledge and some systematic studies, we propose the risk assessment on ships collision and the recommendation for reducing ships collision at sea.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2015.10a
• /
• pp.47-48
• /
• 2015

VTSO make a decision which one will be danger and what to expect ship's actions due to each encountering situation with CPA(Closest Point of Approach) and TCPA(Time to Closest Point of Approach) by monitoring ship's vectors(Course & Speeds) in real-time through the VTS system. This study is the fundamental research for developing algorithm and system that does not decide the collision risk in one's own ship's viewpoints, but it identifies the related ships into danger through the third party(VTS ) in real time.

• Journal of Navigation and Port Research
• /
• v.34 no.2
• /
• pp.97-103
• /
• 2010

It has been recognized that the risk from the vulnerability of GPS can lead to the extreme damage in the infrastructure of the civil and military in recent years. As an example, the intentional interference to GPS signal, named GPS jamming, was really performed to misguide GPS guided weapons during Iraq war in 2003, and the fact has also followed by the serious issues on GPS in civilian community. In the modernized military society, the navigation warfare(NAVWAR) based on the GPS jamming has been emerged and introduced as a military operation. The intentional interference to the future global navigation satellite system(GNSS) involving GPS must be also an important issue to civilian users in near future. This study is focused on the fundamental research prior to the research on "Potential principle of NAVWAR" under NAVWAR of the future warfare. In this paper, we would study on the investigation of NAVWAR based on electronic warfare(EW) and analyze characteristics of the jamming against GNSS's receivers. Then the general mechanism on GNSS jamming is proposed.

• Journal of Positioning, Navigation, and Timing
• /
• v.11 no.2
• /
• pp.109-117
• /
• 2022

This paper proposes a method for detecting flight anomalies of drones through the difference between the command of flight controller (FC) and the navigation solution. If the drones make a flight normally, control errors generated by the difference between the desired control command of FC and the navigation solution should converge to zero. However, there is a risk of sudden change or divergence of control errors when the FC control feedback loop preset for the normal flight encounters interferences such as strong winds or navigation sensor abnormalities. In this paper, we propose the method with a deep neural network model that predicts the control error in the normal flight so that the abnormal flight state can be detected. The performance of proposed method was evaluated using the real-world flight data. The results showed that the method effectively detects anomalies in various situation.

• Journal of Navigation and Port Research
• /
• v.36 no.10
• /
• pp.795-801
• /
• 2012

This paper describes theoretical approach methodology for the Probability based risk Evaluation Techniques (PET) to monitor the risk levels of small-sized sea floater as like a yacht pier. The risk decision-making process by risk criteria with five-step scales is the core concepts of PET. These five-step scales are calculated from cumulative probability distribution of response functions for the sea floater motions using closed-form expressions. In addition, The risk decision-making process of PET with the risk criteria is proposed in this work. To verify the usability of PET, simulation experiments are carried out using mimic signals with the electrical specifications of ADIS16405 sensor that is to be use as measurement tool for the floater motions. As results from experiments, the risk evaluation error by PET shows 0.38 levels in maximum 5.0 levels. These results clearly shown that the proposed PET can be use as the monitoring techniques.

• Proceedings of KOSOMES biannual meeting
• /
• 2018.06a
• /
• pp.148-148
• /
• 2018

• Journal of Navigation and Port Research
• /
• v.34 no.6
• /
• pp.405-415
• /
• 2010

To assess the possible collision risk between Mokpo Harbour Bridge, which is under construction, and passing vessels, we proposed Real-Time Bridge-Vessel Collision Model (RT-BVCM) in this paper. The mathematical model of RT-BVCM consists of the causation probability by the vessel aberrancy due to navigation environments, the geometric probability by the structural feature of a bridge relative to a ship size and, the failure probability by the ship collision track and the stopping distance which is not to come to a stop before hitting the obstacles. Then, the probabilistic mathematical model represented as risk index with the risk level from 1 to 5. The merit of the proposed model to the collision model proposed by AASHTO (American Association of State Highway and Transportation Officials) is that it can provide enough time to take adequate collision avoiding action. Through the simulation tests to the two kinds of test ships, 3,000 GT and 10,000 GT, it is cleary found that the proposed model can be used as a collision evaluation model to the passing vessel and Mokpo Harbour Bridge.

• Journal of the Korea Society for Simulation
• /
• v.25 no.4
• /
• pp.127-135
• /
• 2016

Even thought modernized marine navigation devices help navigators, marine accidents has been often occurred and ship collision is one of the main types of the accidents. Various studies on the assessment method of collision risk have been reported, and studies using fuzzy theory are remarkable for the reason that reflect linguistic and ambiguous criteria for real situations. In these studies, collision risks were assessed on the assumption that the current state of navigation ship would be maintained. However, navigators ignore or turn off frequent alarms caused by the devices predicting collision risk, because they think that they can avoid the collisions in the most of situations. This paper proposes a model of predicting ship collision risk considering the general patterns of collision avoidance, and the approach is based on fuzzy inference and discrete event system specification (DEVS) formalism.

• Journal of Navigation and Port Research
• /
• v.30 no.7
• /
• pp.561-566
• /
• 2006

In this paper, we propose a new ship scheduling set packing model considering limited risk or variance. The set packing model is used in many applications, such as vehicle routing, crew scheduling, ship scheduling, cutting stock and so on. As long as the ship scheduling is concerned, there exits many unknown external factors such as machine breakdown, climate change and transportation cost fluctuation. However, existing ship scheduling models have not considered those factors apparently. We use a quadratic set packing model to limit the variance of expected cost of ship scheduling problems under stochastic spot rates. Set problems are NP-complete, and additional quadratic constraint makes the problems much harder. We implement Kelley's cutting plane method to replace the hard quadratic constraint by many linear constrains and use branch-and-bound algorithm to get the optimal integral solution. Some meaningful computational results and comments are provided.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2011.06a
• /
• pp.234-236
• /
• 2011

Saigon Port within the port system of the Vietnam Maritime sector is one of the port having highest throughput and productivity in the country. The marine traffic of Saigon water ways is the heaviest in Vietnam and the number of marine accidents in this area are much higher than the others area in Vietnam. In order to reduce the risk of the accident in Saigon fairway, this paper concentrates on marine accident frequency in this area. The marine traffic and the marine accident were analyzed to find out the probability of vessel collision and the marine traffic risk. It follows that the main shipping route through Saigon fairway has the high risk of ship-ship collision.