• Journal of IKEEE
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• v.23 no.3
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• pp.941-946
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• 2019

In this paper, the author analyzed the PCI (Physical Cell Identification) allocation methods in the LTE (Long Term Evolution) SON (Self Organization Network) environment. A variety of techniques have been proposed for how to allocate PCI, and the LTE standard fundamentally explained that collision between a cell and neighbor cells arise while a cell assign the PCI. Therefore, in this paper, the author examined the scenarios of PCI collision, weak collision, and confusion proposed by LTE specification. In addition, the cell central approach and the distributed approach were discussed as solutions for each scenario. In this paper, the author reviewed the approach of graphic coloring technique which was studied recently and explained the strategy of central approach.

• Journal of Navigation and Port Research
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• v.46 no.2
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• pp.99-109
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• 2022

A report released by the Chinese Maritime Court found that the natural environment and other objective factors have greatly reduced the risk of ship collision accidents with the advancement of technologies. However, collisions between merchant ships and fishing boats occur frequently along the coast during fishing seasons, which should be highly valued. International conventions and domestic legislation in China comprise detailed laws with respect to ship collisions, but the theory of ship collision infringement needs to be improved, enriched, and developed. Meanwhile, the development of the tort liability law provides theoretical support for ship collision infringement. As far as China's ship tort legal system is concerned, the research on ship collision tort damage compensation is relatively extensive, and the constitutive elements and causality of ship collision tort liability have also been studied in depth. The purpose of this paper is to explore the domestic legislation applicable to disputes related to ship collisions in China. As these laws are unclear on the resolution of disputes resulting from ship collisions, significant attention has been focused on the final judgments by the Supreme Court of China (SPC), as well as the judicial judgments set by the Maritime Court of China.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.476-481
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• 2023

Objective : The latest version of the Leksell Gamma Knife Icon^TM allows for mask- and frame-based fixation. Although mask fixation provides fractionated treatment and immobilization using a noninvasive method, it is not free from collision. The authors investigated the collision problem with a modified mask fixation method. Methods : This study presents a case of two meningiomas in the frontal area, where a collision occurs in the occipital area. A modified mask fixation method was introduced to avoid the collision : first, the edges of the head cushion were cut off and polystyrene beads with a diameter of approximately 5 cm were removed. Next, the head cushion was sealed using a stapler. Finally, the head cushion was flattened in the adapter. We compared the shot coordinates, 3-dimensional (3D) error, clearance distance, and vertical depth of the head cushion between the initial and modified mask fixations. Results : When comparing the initial and modified mask fixations, the difference in the shot coordinates was +10.5 mm along the y-axis, the difference in the 3D error was approximately 18 mm, and the difference in clearance was -10.2 mm. The head cushion was approximately 8 mm deeper in the modified mask fixation. Conclusion : Based on these findings, we recommend a modified mask fixation method for gamma knife radiosurgery using ICON with a collision.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.1
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• pp.15-22
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• 2009

Auto-navigation algorithm have been studied to avoid collision and grounding of a ship due to human error. There have been many research on collision avoidance algorithms but they have been validated little on the real coastal traffic situation. In this study, a Collision Avoidance algorithm is developed by using Fuzzy algorithm and the concept of Changeable Action Space Searching (CAS). In the first step, on a basis of collision risk calculated from fuzzy algorithm in the current time(t=to), alternative Action Space for collision avoidance is planned. In the second step, next alternative Action Space for collision avoidance in the future($t=to+{\Delta}t$) is corrected and re-planned with re-evaluated collision risk. In the third step, the safest and most effective course among Action Space is selected by using optimization method in real time. In this paper, the main features of the developed collision avoidance algorithm (CAS) are introduced. CAS is implemented in the ship-handling simulator of MOERI. The performance of CAS is tested on the situation of open sea with 3 traffic ships, whose position is assumed to be informed from AIS. Own-ship is fully autonomously navigated by autopilot including the collision avoidance algorithm, CAS. Experimental results show that own-ship can successfully avoid the collision against traffic ships and the calculated courses from CAS are reasonable.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.488-498
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• 2022

Collision prevention education, which takes up the longest time among officer training courses, is one of the most important training and practice courses for trainees. The purpose of this study is to investigate the trainees' perception of collision risk in order to develop a systematic and quantified collision prevention training course. For this, factors for judging collision risk were derived from previous studies, and each trainee's perspective on collision risk was derived for each scenario through a questionnaire survey for trainees. Using the PARK Model, the same was compared with the collision risk perceived by the officer. Resultingly, it was found that trainees and of icers consider the distance to other ships the most important among collision risk factors. Additionally, although the risk trends of two groups for each scenario were similar, the average risk of trainees (5.39) was higher than that of officers (5.20). However, the trainees perceived a lower level of risk than the officers in certain scenarios, and this is judged to be the result of the trainees' lack of navigational experience. This study is expected to be used as basic data for the development of collision prevention practice education by quantitatively suggesting the difference between the collision risk of trainees and officers respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.462-469
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• 2023

In this study, we propose a method for evaluating the risk of collision between ships to support determination on the risk of collision in a situation in which ships encounter each other and to prevent collision accidents. Because several uncertainties are involved in the navigation of a ship, must be considered when evaluating the risk of collision. We apply the Dempster-Shafer theory to manage this uncertainty and evaluate the collision risk of each target vessel in real time. The distance at the closest point approach (DCPA), time to the closest point approach (TCPA), distance from another vessel, relative bearing, and velocity ratio are used as evaluation factors for ship collision risk. The basic probability assignments (BPAs) calculated by membership functions for each evaluation factor are fused through the combination rule of the Dempster-Shafer theory. As a result of the experiment using automatic identification system (AIS) data collected in situations where ships actually encounter each other, the suitability of evaluation was verified. By evaluating the risk of collision in real time in encounter situations between ships, collision accidents caused by human errora can be prevented. This is expected to be used for vessel traffic service systems and collision avoidance systems for autonomous ships.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.656-659
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• 1997

In order to improve vehicle safety, collision warning systems have been proposed by many researchers. This paper presents several algorithms to determine the degree of real end collision by using fuzzy logic and neural networks. In order to provide realistic data for the algorithm design, a data collection system has been installed on a passenger car.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.169-176
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• 2004

Offshore structure crossing navigation waterways must not only be designed to resist gravity, wind, and earthquake load, but also be capable of resisting ship and barge collision load. Current specifications for offshore structure design provide empirical relationships for computing impact loads generated during barge collision, however, these relationships are based on the limited experimental data. In this paper, the dynamic finite element analysis is used to computing force for vessel collision scenarios to offshore structures. Results obtained from the ANSYS/LS-DYNA are compared to AASHTO bridge design specifications.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.759-762
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• 1991

In this paper an algorithm is presented which serves for collision avoidance between robots with working space. The method is based on the concept of a hierarchical coordinator and permits an on-line application. Computing possible collision points a collision_free trajectory for the robot with no right_of_way precedence is generated. The computations are based on the states of the robots concerned including their practicable accelerations and velocities.

• Proceedings of KOSOMES biannual meeting
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• 2003.05a
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• pp.99-104
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• 2003

Vessel collision accidents have been investigated by means of questioning the persons involved and plotting manually the stated situation. But the repetitive plotting by hand can cause the investigator to make some errors, and it can be connected to a wrong judgement. In this paper, we proposed a simulator for reconstructing and analyzing vessel collision accidents at sea, where the given situation is plotted automatically on it. We verified validity of the system by applying it to some collision accidents.