• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.33-39
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• 2006

In this paper, the collision avoidance of Unmanned Aerial Vehicles(UAVs) by applying the Traffic alert and Collision Avoidance System II(TCAS-II) is introduced. The performances of two UAVs whose maximum vertical rates are different each other are compared and analysed by not only converting many TCAS-II commands into an autopilot input but also implementing a computer program based on the Minimum Operational Performance Standards for TCAS-II. As the alternative to a possible Near Mid-Air Collision for UAVs whose maximum vertical rates are low, we have proposed a modified algorithm considering the maximum vertical rate and altitude. The modified algorithm is available on the assumption that a wider surveillance range is provided by a ADS-B system.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.3
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• pp.27-33
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• 2010

The goal for the CD&R system is to predict that a conflict is going to occur in the future, communicate the detected conflict to a human operator, and, in some cases, assist in the resolution of the conflict situation. To provide insight into different methods of conflict detection and resolution, a literature review of previous research models and current developmental and operational systems was performed. This paper focuses only on the specific attributes of each model, not on the depth to which a model has been analyzed, validated, or accepted. Thus, care should be taken to remember that a model that seems to be simple according to our categorization scheme may be significantly more viable than an apparently sophisticated model.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.240-248
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• 1999

This paper presents a lane-change collision avoidance control algorithm for autonomous vehicles that will be used in AHS(Automated Highway System). In the proposed control algorithm, nominal control inputs are generated by solving the inverse vehicle dynamic equations of motion for a lane-change maneuver. In addition, a corrective steering input from preview as well as DYC (Direct Yaw Moment Control) may be included to reduce unpredictable errors and to insure yaw directional stability, respectively. The performance of the algorithm is evaluated with an ABS HILS system which consist of 17 DOF vehicle model and real ABS hardware parts. The HILS simulation results show that the proposed algorithm may be used for emergency lane-change maneuvers for autonomous vehicles.

• Journal of Auto-vehicle Safety Association
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• v.11 no.3
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• pp.19-29
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• 2019

Recently, autonomous vehicles have been studied actively. Autonomous vehicles can detect objects around them using their on board sensors, estimate collision probability and maneuver to avoid colliding with objects. Many algorithms are suggested to prevent collision avoidance. However there are limitations of complex and diverse environments because algorithm uses only the information of attached environmental sensors and mainly depends on TTC (time-to-Collision) parameter. In this paper, autonomous driving algorithm using I2V communication-based cooperative sensing information is developed to cope with complex and diverse environments through sensor fusion of objects information from infrastructure camera and object information from equipped sensors. The cooperative sensing based autonomous driving algorithm is implemented in autonomous shuttle bus and the proposed algorithm proved to be able to improve the autonomous navigation technology effectively.

• Journal of Space Technology and Applications
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• v.3 no.3
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• pp.280-300
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• 2023

This paper includes the development and operational status of the space object collision risk management system operated by the Korea Aerospace Research Institute. Currently, it monitors 6 low-orbit satellites and 3 geostationary satellites for collision risks 24 hours, enabling prompt collision avoidance maneuvers to ensure safe and stable operations. Since Chinese anti-satellite test (ASAT) in 2007, the monitoring of collision risks between space objects and operational satellites has been taken seriously, leading to the development of various collision risk management systems to respond quickly and efficiently to such situations. This paper provides an introduction to the space object collision risk management system developed from 2007 to the present, the current status of artificial space objects around Earth, and the system currently in operation. Additionally, it outlines future prospects and plans for the system.

• 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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• v.29 no.1
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• pp.77-83
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• 2005

In collision avoidance problem of a ship, collision risk model is usually set up using the interview results fron experts who sit on a simulator by varying parameters, in which DCPA and TCPA are commonly used. This method, however, has the weakness in that not only it is expensive but also it shows different results depending on the inerviewees and other navigational parameters. In this study, a fuzzy inference system is designed based on own ship's maneuverability verified fron simulation instead of interviewing navigators. The time and distance corresponding to the collision risk value on which avoidance maneuver should be started are set to the minimum marginal time at which own ship starts maneuvering and the minimum marginal distance suggested by marine traffic rules respectively. This system can be recorfigured as a nonlinearity-strengthened one by increasing the number of fuzzy membership functions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.752-761
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• 2014

With increasing of interest in quad-rotor which has excellent maneuverability recently, a various types of multi-rotor aircraft was developed and commercialized, and there are many kinds of leisure products to be easily operated. In these products, the AR.Drone manufactured by Parrot has an advantage that it is easily operated by user due to the its internal stabilization loop in the on-board computer. Thus it is possible to design the unmanned UAV system easily by using this AR.Drone and its inner loop for the stabilization. For this advantage, KARI(Korea Aerospace Research Institute) has been developing the indoor swarming flight system by using multiple AR.Drones. For this indoor swarming flight, it is necessary that not only the position controller for each AR.Drone, but also the collision avoidance algorithm. Therefore, in this paper, the collision avoidance controller is provided for the swarm flight by using these AR.Drones.

• Journal of Navigation and Port Research
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• v.32 no.7
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• pp.521-527
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• 2008

The Istanbul Strait is one of the important waterways in the world. And its southern entrance has a highly congested local traffic. Till now there are several studies regarding how the Istanbul Strait is dangerous to navigate and how those dangers can be mitigated. But there is no study regarding local traffic which is posing great collision risk. In a certain traffic area, marine traffic safety assessment parameters are traffic volume, frequency of collision avoidance maneuver, traffic density, traffic flow and potential encounter, In this paper local traffic volume, traffic flow and potential encounter number of local traffic vessels and possibility of collision are investigated in order to find degree of danger at the southern entrance of the Istanbul Strait. Finally by utilizing those, risky areas are determined for southern entrance of the Istanbul Strait. Results have been compared to a previous study regarding risk analysis at congested areas of the Istanbul Strait (Aydogdu, 2006) and consistency of the results were presented.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.2
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• pp.257-264
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• 2015

This study is intended to provide navigator with specific information necessary to assist the avoidance of collision and the operation of ships to evaluate the maneuverability of dead weight tonnage 8,000 tons Oil/Chemical tanker. The actual maneuvering characteristics of ship can be adequately judged from the results of typical ship trials. Author carried out sea trials based full scale for turning test, Z" maneuvering test, man overboard rescue maneuver test, inertia stopping test. Consequently, $2^{st}$ Overshoot yaw angle of the semi balanced rudder and flap rudder in ${\pm}20^{\circ}$ zig-zag test showed $22.2^{\circ}$ and $18.0^{\circ}$, respectively. The maneuverability of the vessel was good in the flap rudder. The man overboard rescue maneuver maneuverability test was most favorable in the flap rudder and the full load condition. The results from tests could be compared directly with the standards of maneuverability of IMO and consequently the maneuvering qualities of the ship is full satisfied with its.