• 선박안전
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• 통권36호
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• pp.71-78
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• 2014

If we don't know the intention of altering course of a target ship when being in a head-on or a crossing situation, we may be confused about our decision making to change our course for collision avoidance and be in a danger of collision. In order to solve these problems, we need to develop an automatic detection system on altering course of a target ship for efficient collision avoidance. In this paper, we proposed an early detection system on altering course of a target ship using the steering wheel signal. This system will contribute to the reduction of collision accidents and also be used to the VTS system and the analysis of marine accidents.

• 한국해양공학회지
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• 제24권2호
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• pp.25-33
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• 2010

Collision between vessels may lead to structural damage and penetration of hulls. The structural damage of a hull may eventually bring about global collapse of the hull girder and outflow of oil, which would contaminate seawater. Therefore, various regulations require the strength of a vessel after collision to satisfy given criteria, and owners usually request collision analyses to confirm the structural safety of their vessels. In the process of designing a vessel to satisfy the collision strength criteria, the strength has been assessed mostly by conducting collision analyses using numerical techniques, such as dynamic, non-linear, finite-element analysis. Design is an inherently iterative process during which many changes are necessary due to the endless needs for reinforcement and modification. Numerical techniques are not adequate for coping with a situation in which collision analysis is frequently required to provide the revised results that reflect the repetitive changes in designs. Numerical techniques require a lot of time and money to conduct in spite of recent improvements in computing power and in the productivity of modeling tools. Therefore, in this paper, an analytical technique is introduced and a collision problem is idealized and simplified using reasonable assumptions based on appropriate background. The technique was applied to an example of an actual FPSO and verified by comparing the results with results from the numerical technique. A good correlation was apparent between the results of the analytical and numerical techniques.

• 로봇학회논문지
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• 제3권4호
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• pp.323-330
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• 2008

This work deals with a 4-DOF flexible continuum robot that employs a spring as its backbone. The mechanism consists of two modules and each module has 2 DOF. The special features of the proposed mechanism are the flexibility and the backdrivability of the whole body by using a spring backbone. Thus, even in the case of collision with human body, this device can ensure safety. The design and the kinematics for this continuum mechanism are introduced. The performance of this continuum mechanism was shown through simulation and experiment.

• 한국안전학회지
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• 제34권5호
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• pp.139-143
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• 2019

In this study, we tried to derive the most severe scenario and its critical speed by 1-D collision simulation with a variable formation vehicle in order to prepare for the change of demand in Seoul Metropolitan Subway Line 3, which is operated by fixed arrangement. After establishing various collision scenario conditions, the friction coefficient between the wheel and the rail was evaluated as 0.3, which is considered to be severe. As a result of analysis according to all scenarios, the most severe scenario conditions were confirmed by comparing rubber shock absorber performance and vehicle collision deceleration. In addition, a typical wheel-rail friction coefficient was derived through accident cases, and the analysis was performed again and compared. Finally, the criterion of the critical speed in the condition of the friction coefficient of the normal wheel - rail condition was confirmed.

• 자동차안전학회지
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• 제13권3호
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• pp.41-46
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• 2021

The number of big traffic accident cases of pedestrian death appeared to be minor, however compared to death rate in car to car accidents is very high and quite a few of the pedestrian death rates among all traffic accidents are counted to be almost 40%. Previous pedestrian safety studies were mostly aimed at reducing the degree of pedestrian injuries from a vehicle to pedestrian collision, and less at preventing a collision itself. This research was conducted with a method of using road facilities to prevent vehicles from rushing into the sidewalk. This research used one of the collision analyzing programs, called PC-Crash to simulate the vehicle rushing into the sidewalk. Based on the program, it could derive an optimal safe zone location where the pedestrian can wait for the pedestrian light safely. Also, changing road facilities such as pedestrian light pillars or signal controllers can widen 440% compared to the present safe zone. Accordingly, researchers have to consider a method to analyze and apply pedestrian safe zones along with road facilities location when designing a road.

• 해양환경안전학회지
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• 제22권6호
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• pp.593-599
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• 2016

인천대교는 인천국제공항과 송도국제도시를 연결하는 길이 13.38 km, 경간 800 m의 대형 교량으로 시간당 73.8(vessel/hour)척의 선박이 통항하고 있다. 본 연구에서는 인천대교 건설 시 설계되었던 인천대교 충돌방지공의 안전기준을 바탕으로 인천대교를 통항하는 선박의 중량에 따른 안전한 통항 속력을 제시하고자 한다. 연구방법은 AASHTO LRFD에서 제시한 선박 충돌에너지와, 선박 충돌 속도, 수리동적질량계수를 고려하여 통항 선박의 안전 속력을 제시하고자 한다. 인천대교의 충돌방지공은 10만DWT급 선박이 10노트로 통항 할 수 있도록 설계되었다. 본 연구에서는 대상선박(30만DWT급)의 선속조건 및 화물 상태의 비교 분석을 통하여 각각의 충돌에너지에 따른 제한 속력을 산정하는 방식으로 통항 선박의 안전 속력을 제시하였다. 또한 해당 수역의 조위에 따른 통항 선박의 안전 속력을 추가적으로 분석하였다. 대상선박(30만DWT급)을 통한 연구 결과 최대 15만DWT급 선박이 평균조위 이상의 수심에서 최대 7노트 속력으로 운항이 가능한 것으로 나타났으며, 경하상태(Ballast condition)에서는 최대 8노트의 속력으로 인천대교를 통항할 수 있는 것으로 분석되었다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.226-229
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• 2006

The safety of on-going ships is one of important concerns in the view of environment and human life. The ship in bad condition is likely to be subjected to accidental loads such as collision. Once she has one or several minor collision damages in the form of circle or ellipse, her ultimate strength under compression or tension load will be reduced. Here, it is important to evaluate the reduction ratio of ultimate strength due to the damage from safety point of view. The problem of strength reduction of a plate with cutout such as opening hole has been treated by many researchers. As a result, a closed-form formula on the reduction of ultimate strength of a plate considering the effect of several forms of cutout was suggested. However, the structure of ships is composed of a plate and a stiffener so-called a stiffened plate, and it is likely to be damaged at a plate and stiffeners together in collision. This paper is to investigate the effect of minor collision damage on ultimate strength of a stiffened plate by using numerical analysis. For this study, the shape of minor collision damage of a stiffened plate was made by using contact algorithm. The deformed shape was used as an initial shape for ultimate stress analysis. Then, a series of nonlinear FE analysis was conducted to investigate the reduction effects of ultimate strength of the stiffened plate. The boundary condition was applied as simply supported at all boundaries, and the tripping of stiffener among failure mode under compression loading was neglected. These results were settled in the form of reduction ratio between ultimate of original intact stiffened plate and that of damaged stiffened plate.

• 한국인터넷방송통신학회논문지
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• 제19권5호
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• pp.9-17
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• 2019

IoT 환경이 보편화됨에 따라 사람의 직접적인 개입 없이 물체와 물체 사이의 통신 환경을 구축하는 M2M 환경의 안전성이 중요시 되고 있다. 무선 통신 환경의 특성상 데이터 노출, 위조, 변조, 삭제 및 개인 정보 보호와 같은 다양한 측면에서 보안 위협에 노출 될 가능성이 존재하고, 안전한 통신 보안 기술이 중요한 요구 사항으로 다뤄진다. 본 논문에서는 해시충돌을 이용하여 기존 'M2M 통신 환경에서 트랩도어 충돌 해쉬을 이용한 그룹키 생성 및 교환 기법' 연구의 한계점을 확인하고, 스니핑 공격에 안전한 그룹간에 키를 생성하고 이를 세션 키와 교환하는 기법과 그룹 키 생성 후에 장치와 게이트웨이의 인증을 확인하는 메커니즘을 제안한다. 제안 된 방법은 충돌 메시지 및 충돌 해시의 특이성을 이용하여 그룹 통신 섹션의 위장 공격, 중간자 공격, 재전송 공격과 같은 공격 저항을 가지며, 해시충돌의 취약점에 대해 안전성을 증명하는 기법이다.

• 대한조선학회논문집
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• 제56권1호
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• pp.58-65
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• 2019

The stability, reliability and efficiency of a smart ship are important issues as the interest in an autonomous ship has recently been high. An automatic collision avoidance system is an essential function of an autonomous ship. This system detects the possibility of collision and automatically takes avoidance actions in consideration of economy and safety. In order to construct an automatic collision avoidance system using reinforcement learning, in this work, the sequential decision problem of ship collision is mathematically formulated through a Markov Decision Process (MDP). A reinforcement learning environment is constructed based on the ship maneuvering equations, and then the three key components (state, action, and reward) of MDP are defined. The state uses parameters of the relationship between own-ship and target-ship, the action is the vertical distance away from the target course, and the reward is defined as a function considering safety and economics. In order to solve the sequential decision problem, the Deep Deterministic Policy Gradient (DDPG) algorithm which can express continuous action space and search an optimal action policy is utilized. The collision avoidance system is then tested assuming the $90^{\circ}$intersection encounter situation and yields a satisfactory result.

• 한국항행학회논문지
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• 제28권4호
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• pp.480-489
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• 2024

국토교통부는 2022년 항공안전 및 운항 효율성 향상을 목적으로 제주와 부산을 잇는 항공로, Y579의 일부 구간을 복선화하였다. 복선화 이전에는 의도적으로 항공기를 진행 방향의 우측으로 이탈시키는 offset 절차를 적용하여 반대 방향으로 비행하는 항공기들을 횡적으로 분리하였으나 '22.12.1. Offset 절차를 폐지하는 대신, 두 개의 평행 항공로 Y571(부산방향)과 Y572(제주방향)를 신설함으로써 안전성과 효율성을 도모하였다. Y571, Y572 항공로의 복선화에는 여러 가지 측면에서 의의가 있다. 본 연구는 신설 항공로에 대해 안전도를 분석하는 한편, 이전에 적용하던 Offset 절차와의 안전도를 비교하여 복선화의 효과를 분석하였으며 공역 운용의 관점에서 의의를 제시하였다. 정량적 안전평가는 Reich CRM (collision risk model)의 변형된 모델을 활용하였다. 분석 결과 복선화 이후 안전수준이 향상되었으며 공역의 활용에서도 효과가 있음을 확인하였다.