• Journal of the Society of Naval Architects of Korea
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• v.57 no.4
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• pp.182-190
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• 2020

This study reports a series of drop impact tests performed to generate denting damages on stiffened plates and their residual ultimate strength tests under axial compression. The models were fabricated of general structural steel, and each model has six longitudinal stiffeners and two transverse frames. Among six fabricated models, four were damaged, and two were left intact for reference. To investigate the effects of collision velocity and impact location on the extent of damage, the drop height and the impact location were changed in each impact test. After performing the collision tests, the ultimate axial compression tests were conducted to investigate the residual strengths of the damaged stiffened plates. Finite element analyses were also carried out using a commercial package Abaqus/Explicit. The material properties obtained from a quasi-static tensile tests were used, and the strain-rate sensitivity was considered. After importing the collision simulation results, the ultimate strength calculations were carried out and their results were compared with the test data for the validation of the finite element analysis method.

• Journal of Korean Society of Disaster and Security
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• v.16 no.2
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• pp.75-83
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• 2023

In general, bridges are facilities installed for the purpose of easily passing through sections such as valleys and rivers. Railway bridges that run through downtown areas are damaged due to external factors such as earthquakes and collisions with passing vehicles, resulting in serious human casualties. This can cause serious human and properties damage, such as functional paralysis in downtown areas. Depending on the degree of damage, repair work such as partial repair or full replacement is in progress for the bridge where the collision occurred. When damage or deformation occurs due to collision, the repair method is determined according to the degree of deformation and the degree to which the load capacity of the bridge is affected by the deformation. In this study, a numerical analysis review was performed on the repair work for the local deformation caused by the collision of a vehicle on an old railway bridge installed and in operation in an urban area. To this end, a structural safety review of the bridge for local deformations caused by vehicle collisions was conducted. In this paper, a repair method for the accident bridge was presented based on the analysis results.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.107-112
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• 2013

Base on insurance vehicle collision and bodily injury claim reports, 23,655 cases of vehicle to vehicle accidents occurred in Korea 2010 are investigated in order to understand vehicle damage severities, repair costs and occupant injury types. The results of our statistical analysis reveal that minor damages with small dent or scratches on vehicle body panels which is assumed to imply during very low speed crashes are major portion of accident severities types. The most vulnerable body regions due to the real-world accident are neck. The 86.3% of total injured driver in minor rear damaged vehicles has reported neck pains and they are followed by whole bodies and head but with much lower occurrence rates.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.36-37
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• 2014

It is necessary to develop highly sophisticated Modeling & Simulation (M&S) system for the scientific investigation of marine accident causes and for the systematic reproduction of accidental damage procedure. To ensure an accurate and reasonable prediction of marine accidental causes, such as collision, grounding and flooding, full-scale ship M&S simulations would be the best approach using hydrocode, such as LS-DYNA code, with its Fluid-Structure Interaction (FSI) analysis technique. The objectivity of this paper is to present three full-scale ship collision, grounding and flooding simulation results of marine accidents, and to show the possibility of the scientific investigation of marine accident causes using highly sophisticated M&S system.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.616-621
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• 2004

In this paper, the crush characteristics of a tilting train express (TTX) M-car design are evaluated with a head-on collision scenario. Its body shell is divided into three parts - front end, middle section, and rear end. For each part, crush-force relation is evaluated numerically through 3-dimensional shell element analysis with LS-DYNA. TTX's embody structure is a hybrid type structure made of steel and composite materials. Composite sandwich panels are modeled as layered shells whose layers have different material properties. And a damage material model is used to consider the effect of stiffness degradation during deformation. The crush characteristics obtained from these calculations will be used as material modeling data of full-rake collision analyses.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.96-103
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• 2009

In 2006, Jeju Island in South Korea experienced a crisis, no electricity for three hours anywhere in the entire island. This incident was caused by a domino effect that occurred after one of the submarine power cables connecting the island to Haenam, a coastal city on the mainland, was damaged by an external load, probably from a ship anchor or a steel pile being used in marine farming. This study presents a collision analysis of a new submarine power cable protector called arch type reinforced concrete. For the analysis, a dynamic finite element program, ANSYS AUTODYN, was used to examine the displacement and stress of the submarine power cable protector using different material models (RHT concrete model, Mohr.Coulomb concrete model). In addition, two reinforcing bar spacings, 75 mm and 150 mm, were considered. From the analyses, the effects of the parameters (concrete model and spacing) on the results (displacement and stress) were analyzed, and the relations between the damage and parameters were found.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.26-32
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• 2017

Enlargement and speed-up of a ship and diversification of ship's type have served to greatly increase the importance of marine transport means. It's reported that accident occurrence frequency of collision is high next to engine damage among the ship accident types, and that the accident ratio according to human factors is also high. In addition, ship accidents come to occur caused by complex cause factors rather than a sole cause factor, it is necessary to investigate the cause factors through the written verdict. This study proposed the cause factors of collision ship accident on the basis of human factors in collision ship accident among the written verdicts provided by the Korean Maritime Safety Tribunal, and inquired into the cause factor and effect through the correlation analysis of accident occurrence factors. Also, this study predicted the collision accident through analyzed the major cause factor of the occurrence at the zero minute when collision on the basis of the time taken from the time point of detecting collision of ships to the time point of collision occurrence. This study used commercial software-Statistical Package for Social Sciences (SPSS Ver21.0) to do correlation analysis. For time analysis, this study analyzed the cause factor and time by analyzing the time taken from the time point of detected ships to the time point of collision occurrence on the basis of the written verdicts. The study analysis showed that there were many cases of collision ship accidents occurrence caused by more than two sorts of cause factors, and that the case (zero minute) where there is no time to spare for collision avoidance accounted for 36.1 %, and negligence in guard or surveillance of the other ship, and sailing while drowsy, or drinking was a contributor to an accident. Poor watch keeping is very strong relationship with pool ready for sail.

• 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.22 no.3
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• pp.259-267
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• 2016

The study performs a risk analysis on container ship accidents using accident data collected over the six years from 2006 to 2011, presents the resulting risk level, and suggests three risk mitigation measures to reduce the overall risk, for the safer operation of container ships. More specifically, starting from the initial accident of collision, we developed 13 different accident scenarios using event tree analysis based on which the overall risk level was obtained and presented as a FN curve. Since diverse human factors are the main cause of most of the ship accidents, our study focuses on the effect of reducing human causes on the resulting risk level. For the research we considered the injuries for the calculation of fatality with the help of MAIS. The results show that collision was the main type of accident, accounting for 62 % of all accidents, and the measures employed were proven to be effective in the sense that the risk level was much lowered and the average number of fatalities was also reduced. With more data accumulated, more precise risk level will be calculated with which the practical risk mitigating measures will be also developed. For future study, economic loss and environmental damage as consequences need to be considered.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.169-173
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• 2011

Crash box is introduced to vehicle design to improve the impact performance and reduce the damage of vehicle body at impact speed. The crash box behind bumper can absorb impact energy effectively to improve vehicle safety. Repair cost at collision accident can be cut down by use of this box. The configuration of car body must be designed by considering the characteristic of material due to the deformation of car body happened at impact. Many papers have been published about material of crash box all over the world. The study of crash box with tube expansion type has been going on Korea. This study is done by the simulation analysis about front collisions against 5 kinds of aluminum crash boxes with the basic structure of square section.