• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1484-1486
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• 2015

그리드 기반 공간 분할 방식에서 셀 크기는 성능을 좌우하는 핵심 요소이다. 본 논문에서는 각 셀에서 충돌 검사가 일어나는 빈도에 따라 동적으로 셀의 크기를 제어하는 방식을 제안한다. 각 셀의 충돌 검사 빈도와 인접한 셀과 병합했을 때의 충돌 검사 빈도를 비교하여, 이 차이가 임의의 값보다 작을 때 셀들을 병합하여 하나의 큰 셀로 만든다. 단, 병합할 셀이 여러 개일 경우 충돌 검사 빈도가 작은 셀부터 차례로 병합한다. 이 방식을 통하여 셀의 수 및 업데이트 비용을 줄일 수 있으며 이는 공간상의 객체가 규칙적인 움직임을 보일 때 가장 효율적임을 확인했다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.169-176
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• 2005

An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted annual frequency of bridge collapse, AF, from the ship collision risk assessment is compared to an acceptance criterion. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed AF is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The distribution of the AF acceptance criterion among the exposed piers is generally based on the designer's judgment. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.918-927
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• 2022

The purpose of this study was to investigate the causes of collisions by examining 668 cases of merchant ship collision accidents that occurred during the past 12 years (2010-2021) and analyzed them statistically. Further, the analysis results were applied to propose a human error prevention collision avoidance (HEPCA) model. The statistical annual report of the Korea Maritime Safety Tribunal (KMST) and the collision investigation report were investigated to collect data on the causes of collisions of merchant ships, and frequency analysis was performed using the statistical analysis tool, SPSS Statistics. In the first-stage analysis, the causes of collisions were analyzed targeting 668 merchant ship collision accidents, and in the second-stage analysis, the identified maximum frequency cause factors were analyzed in detail. The analysis results identified that 98 % of the cause of the collision was the human error of the navigator, and the highest frequency was in the order of neglect of look-out > violation of navigation regulations > improper maneuvering. The cause of the neglect of look-out was mainly neglecting continuous monitoring after the first recognition of the target ship. The HEPCA model for human error prevention was proposed by applying the analysis results to the collision case of the investigation report. The results of this study are expected to be used as educational materials at marine navigator educational institutions and in practice for avoiding collisions caused by human errors of navigators.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.1-9
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• 2006

An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted annual frequency of bridge collapse, AF, from the ship collision risk assessment is compared to an acceptance criterion. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed AF is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The distribution of the AF acceptance criterion among the exposed piers is generally based on the designer's judgment. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions. To determine the design impact lateral resistance of bridge components such pylon and pier, the numerical analysis is performed iteratively with the analysis variable of impact resistance ratio of pylon to pier. The design impact lateral resistance can vary greatly among the components of the same bridge, depending upon the waterway geometry, available water depth, bridge geometry, and vessel traffic characteristics. More researches on the allocation model of AF and the determination of impact resistance are required.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.123-134
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• 2006

In this study ship collision risk analysis is performed to determine the design vessel for collision impact analysis of the maritime bridge. Method II which is a probability based analysis procedure is used to select the design vessel for collision impact from the risk analysis results. The analysis procedure, an iterative process in which a computed annual frequency of collapse(AF) is compared to the acceptance criterion, includes allocation method of acceptance criterion of annual frequency of bridge component collapse. The AF allocation by weights seems to be more reasonable than the pylon concentration allocation method because this AF allocation takes the design parameter characteristics quantitatively into consideration although the pylon concentration allocation method brings more economical results when the overestimated design collision strength of piers compared to the strength of pylon is moderately modified. From the assessment of ship collision risk for each bridge pier exposed to ship collision, a representative design vessel for all bridge components is selected. The design vessel size varies much from each other in the same bridge structure depending upon the vessel traffic characteristics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.11-19
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• 2006

In this study ship collision risk analysis is performed to determine the design vessel for collision impact analysis of suspension bridge. Method II in AASHTO LRFD bridge design specifications which is a more complicated probability based analysis procedure is used to select the design vessel for collision impact. From the assessment of ship collision risk for each bridge pier exposed to ship collision, the design impact lateral strength of bridge pier is determined. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed annual frequency of collapse(AF) is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The acceptance criterion is allocated to each pier using allocation weights based on the previous predictions. This AF allocation method is compared to the pylon concentration allocation method to obtain safety and economy in results. This method seems to be more reasonable than the pylon concentration allocation method because AF allocation by weights takes the design parameter characteristics quantitatively into consideration although the pylon concentration allocation method brings more economical results when the overestimated design collision strength of piers compared to the strength of pylon is moderately modified. The design vessel for each pier corresponding with the design impact lateral strength obtained from the ship collision risk assessment is then selected. The design impact lateral strength can vary greatly among the components of the same bridge, depending upon the waterway geometry, available water depth, bridge geometry, and vessel traffic characteristics. Therefore more researches on the allocation model of AF and the selection of design vessel are required.

• Polymer(Korea)
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• v.35 no.6
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• pp.513-519
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• 2011

Molecular simulations via the molecular dynamics method have been carried out to investigate the dynamic collision properties of penetrable-sphere model fluids. The collision frequencies, the mean free paths, the angle distributions of the hard-type reflection and the soft-type penetration, and the effective packing fractions are computed over a wide range of the packing fraction ${\phi}$ and the repulsive energy ${\varepsilon}^*$. The soft-type collisions are dominated for lower repulsive energy systems, while the hardtype collisions for higher repulsive energy systems. Very interestingly, the ratio of the soft-type (or, the hard-type) collision frequency to the total collision frequency is directly related with the Boltzmann factor of acceptance (or rejection) probabilities in the canonical ensemble Monte Carlo calculations. Such dynamic collision properties are shown to be restricted for highly repulsive and dense systems of ${\varepsilon}^*{\geqq}3.0 $and ${\phi}{\geqq}0.7$, indicating the cluster forming structures in the penetrable-sphere model.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.219-221
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• 2023

첨단 디지털기술이 적용된 자율운항선박과 같이 인간의 개입을 획기적으로 줄인 첨단 시스템의 운용은, 대상 시스템의 운용 중 시스템에 영향을 미치는 다양한 변수들의 변화를 실시간으로 검토하여 안전한 시스템 운용을 위한 의사결정을 지원할 수 있는 위험도평가 방법론의 적용이 요구된다. 본 논문은, 자율운항선박의 충돌 사고 위험도를 실시간으로 분석하기 위한 위험도 모델의 개발을 목적으로, 자율운항선박 충돌 사고 시나리오에 대한 위험도분석 작업 수행 내용과 실시간 충돌 위험도를 표현하기 위하여 검토한 간략한 위험도 모델 개념들을 제시하고 있다. 위험도 모델 개발을 위하여, 먼저 자율운항선박의 항해, 통신, 비상대응 기능들을 분석하고, 기능분석 결과를 바탕으로 충돌 사고 빈도 산출을 위한 Fault Tree Analysis와 충돌 사고로 인한 영향 산출을 위한 Event Tree Analysis를 수행하였다. 또한, Fault Tree와 Event Tree의 입력값 중 외부 조건에 따라 변화하는 변수들을 식별하였고, 각 변수들에 입력값은 자율운항선박의 운항 조건에서 발생할 수 있는 가상 데이터를 만들어 사용하였으며, 식별된 각 변수들의 변화로 인한 자율운항선박 충돌 위험도 변화량을 검토하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.801-809
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• 2017

The purpose of this study is to contribute to the prevention of ship collisions by investigating real ship collision cases and statistically analyzing causes of human error for captains and Officers of the Watch (OOW). This study encompassed a total of 109 cases for 218 vessels, which were suitable for the analysis of ship accidents between merchant ships or merchant ships and fishing boats over the 7 years from 2010 to 2016. Data was collected while classifying vessels according to type, Give-way and Stand-on vessels, along with the cause of human error. Factors causing human error were identified after focusing on the cause of each collision given by the OOW ; frequency and cross tabulation analyses were conducted using SPSS, a statistical analysis tool. As a result, the main causes of human error by an OOW in a ship collision situation were that lookout was neglected in a Give-way vessel including radar surveillance (74.3 %) or continuous observation of an opponent vessel was carried out (17.4 %). A major factor for Stand-on vessels was failure to act to avoid collision with another vessel (63.3 %). In particular, most neglect for lookout type merchant ships occurred after the opponent ship was first observed, and a common cause of lookout neglect and neglect of duty was a focus on other tasks during navigational watch time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.89-94
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• 2004

Up to now a lot of the study on ship collision avoidance systems has proceeded actively. However the frequency of ship collision accidents didn't decreased. If there is collision risk in close quarters situation none the less manouvering ship for collision avoidance according to the system, only use of TCPA and DCPA as input factor for collision risk decision is not useful to avoiding collision action. For the recent 5 years by the analysis of first observation distance about approaching ship in domestic collision accidents, nearly $45\%$ of accidents is close first observation less than 2 miles. Therefor it is essential part for safety navigations to study for collision avoidance action in close encounter. In this paper, as foundation study of supporting collision avoidance manoeuvring for navigators, we proposed ship collision avoidance support model in close quarters situation through analysis of collision accidents for effective getting rid of the causes.