• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.121-124
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• 2001

충돌회피 시스템은 선박의 안전 항해에 중요한 역할을 한다. 충돌회피 시스템은 선박이 장애물을 만났을 때 영역전문가인 항해사를 대신하여 피항 행위를 하도륵 지시하는 시스템으로 자선에서 이루어지는 해상 장애물들에 대한 피항 시 그 판단 기준을 각 장애물에 대한 충돌위험도에 둔다. 따라서 본 연구에서는 선박의 충돌회피 시스템의 보다 안전한 충돌회피를 도모하기 위해 충돌회피를 위한 충돌위험도 결정 시스템을 제안한다. 충돌위험도 결정 시스템은 장애물 모델링과 장애물의 충돌위험도 결정의 두 부분으로 구성된다. 장애물 모델링은 선박의 센서에서 나오는 저수준의 자료를 지능형 선박의 타 시스템에서 이용하기 쉽도록 구하는 과정이다. 충돌위험도 결정 시스템의 출력으로 산출되는 충돌위험도는 충돌회피 시스템의 피항 행위 결정에 정보로 사용된다. 본 연구에서는 DCPA와 TCPA를 이용한 기존의 기법에 VCD의 개념을 추가한 새로운 충돌위험도 결정 기법을 제안한다. 입력변수가 되는 DCPA, TCPA, VCD의 퍼지 소속함수를 산출하고 이를 기반으로 퍼지 추론을 이용하여 세부적인 충돌위험도를 결정한다. 본 연구에서 제안하는 기법은 기존의 DCPA와 TCPA만으로 충돌위험도를 결정한 경우보다 상세한 충돌위험도 결정이 가능하다는 장점과 국제해상충돌예방규칙의 내용이 적용되었다는 장점을 지닌다. 제안된 기법은 DCPA와 TCPA 만으로 충돌위험도를 결정한 기법과 비교.평가하여 성능을 검증한다.

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.517-523
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• 2010

There are enormous challenges in the Istanbul Strait- one of the most important, congested and narrow waterways in the world - from the view point of risk determination and risk mitigation for the local traffic. Previously several traffic parameters such as; traffic volume for local vessels, traffic flow and potential encounters of local traffic, in addition to the possibility of collision, were investigated in order to determine the degree of dangers in the southern entrance of the Istanbul Strait. Furthermore, risky zones were also determined in this waterway. On the basis of the results of those, a group of expert was surveyed. These experts were pilots, Vessel Traffic Services Operators (VTS-O), Local Traffic Vessel Captains and Master Mariners who had several experience of navigation through the Istanbul Strait. In order to assess experts perceptions of danger and to propose further studies based on this survey. The questionnaire was analyzed by using SPSS (Statistical Package for the Social Sciences) program version 13.0. Finally, some differences and/or shares on risk perceptions of expert in the Istanbul Strait are considered.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.3
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• pp.19-27
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• 2022

Urban Air Mobility is expected to resolve some problems in urban transportation such as traffic congestion and air pollution. Various studies for a large-scale commercialization of UAM are being actively conducted. To that end, the UAM Traffic Management system aims at securing a safety and an efficiency of UAM operations. In this study, a risk assessment model is proposed to evaluate the risk of collision between a vehicle and surrounding obstacles. The proposed model is conceived from the past studies for determining a proper separation distance between parallel runways for their independent operations. The model calculates the risk that the surveillance system fails to meet a target level of safety for a given buffer zone size between a designed route and surrounding obstacles. The model is applied to one of the routes proposed in K-UAM roadmap to evaluate its performances.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.103-111
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• 2021

The purpose of this study is to study a method for preventing collisions of multiple drones in controlled airspace. As a result of the study, it was proved that it is appropriate as a method to control drone collisions after setting accurate information on the ROI (Region of Interest) area estimated based on the expected drone path and time in the control system as a method to avoid drone collision. As a result of the empirical analysis, the diameter of the flight path of the operating drone should be selected to reduce the risk of collision, and the change in the departure time and operating speed of the operating drone did not act as an influencing factor in the collision. In addition, it has been demonstrated that providing flight priority is one of the appropriate methods as a countermeasure to avoid collisions. For collision avoidance methods, not only drone sensor-based collision avoidance, but also collision avoidance can be doubled by monitoring and predicting collisions in the control system and performing real-time control. This study is meaningful in that it provided an idea for a method for preventing collisions of multiple drones in controlled airspace and conducted practical tests. This helps to solve the problem of collisions that occur when multiple drones of different types are operating based on the control system. This study will contribute to the development of related industries by preventing accidents caused by drone collisions and providing a safe drone operation environment.

• 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.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.86-99
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• 2021

This research proposes the Accident Prevention System to prevent collision accident that can occur due to blind spots such as crossway or school zone using V2I communication. Vision sensor and LiDAR sensor located in the infrastructure of crossway somewhere like that recognize objects and warn vehicles at risk of accidents to prevent accidents in advance. Using deep learning-based YOLOv4 to recognize the object entering the intersection and using the Manhattan Distance value with LiDAR sensors to calculate the expected collision time and the weight of braking distance and secure safe distance. V2I communication used ROS (Robot Operating System) communication to prevent accidents in advance by conveying various information to the vehicle, including class, distance, and speed of entry objects, in addition to collision warning.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.135-144
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• 2007

Space environment becomes more hazardous for satellite because of increasing number of space debris. This research is to analyze collision hazards between KOMPSAT 3 in low-earth orbit and space debris generated by the explosion of FengYun satellite on the January 11, 2007. Based on the observed data of the space debris from FengYun satellite, the mass and number distribution of the debris are estimated including undetectable debris from the explosion of FengYun satellite. The spatial density and flux for the space debris can be calculated according to size. This study also brings out the analysis for the assessment of collision probability and damage probability. The algorithm developed in the current paper can be used to estimate the level of risk due to space debris for the satellites that will be launched in the future.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.173-182
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• 2007

An innovative feature of this study is to propose a methodology for evaluating safety performance in real time based on vehicle trajectory data extracted from video images. The essence of evaluating safety performance is to capture unsafe car-following events between individual vehicles traveling surveillance area. The proposed methodology applied two indices including real-time safety index (RSI) based on the concept of safe stopping distance and time-to-collision (TTC) to the evaluation of safety performance. It is believed that outcomes would be greatly utilized in developing a new generation of video images processing (VIP) based traffic detection systems capable of producing safety performance measurements. Relevant technical challenges for such detection systems are also discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.11
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• pp.1144-1151
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• 2010

The increasing number of orbital debris objects is a risk for satellites because of past 50 years space activities. The LEO (low earth orbit) where KOMPSAT-2 and KOMPSAT-5 are operated is including about 84% of the total space debris. Thus, the space missions need to consider the space debris. In this paper, we analysis the orbit characteristics and spatial density of space debris about KOMPSAT-2 that is in activity and KOMPSAT-5 that will be launched in 2010. Analyzed probability damage and collision with space debris are also performed. ESA MASTER2005 and of NASA DAS2.0 are used to analysis KOMPSAT mission environment. As a result, it is noted that KOMPSAT-2's collision probability was far more than KOMPSAT-5 because KOMPSAT-2's orbit has high density composed space debris.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.1
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• pp.44-51
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• 2023

The Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs) was adopted to prevent ships from colliding with other ships or any object such as the seabed. COLREGs have been codified and refined since the mid-19th century, and have reached the present. Therefore, the terms and sentences used in COLREGs also have distinct academic and legal connotations. However, in the Maritime Safety Act of the Republic of Korea, which translated COLREGs into domestic law, the "risk of collision" and the "danger of collision" was used in the law without distinguishing their meanings. Accordingly, the difference between "risk" and "danger" was analyzed with reference to the definition of risk by an authoritative international organization of the United Nations such as the International Maritime Organization and the International Organization for Standardization as a well-known and authoritative non governmental organization. In addition, the cases codified in COLREGs and translated cases in the Maritime Safety Act were analyzed to highlight the need for amending the Maritime Safety Act. From the perspective of safe navigation, it is expected that the Maritime Safety Act in the future would distinguish between "danger" and "risk" so that the efforts of watch officers to prevent collisions could be further systematized.