• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.564-571
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• 2011

During navigation of warships, sonar domes have been damaged by collision with floating objects like logs. In order to analyze the damage of a sonar dome from collisions with a log, The analytical method and the numerical analysis using ABAQUS are performed. Throughout the analytical method, the mechanism of collision between a sonar dome and log is analyzed. To design a sonar dome, the numerical analysis for A type sonar dome and the B type sonar dome have done considering fluid loading effect around the sonar domes with normal and maximum speeds of the ship, respectively. The numerical analysis results of the A type sonar dome and the B type sonar dome are compared and analyzed.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.1
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• pp.33-41
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• 2011

For the assessment of ultimate longitudinal strengths of damaged hull girders, it is preliminarily necessary to determine the extents and locations of the damages due to severe accidents. This paper deals with the estimation of the damages from collisions and groundings of large-sized vessels where deterministic and probabilistic approaches are investigated. Deterministic damages estimated from MARPOL(or ICLL), ABS and DNV are compared with probabilistic damages from IMO guideline and some references including damage statistic data. Damages from MARPOL show largest one among all the investigated damage estimation, since it was developed not for the residual strength of hull girder but for the damage stability calculation. IMO guideline with high level probability of damage(eg. 95% probability level) also forecasts even severer damage extents than MARPOL. On the other hand, assuming average probability level of damage, the calculated damage sizes are around the one from deterministic approaches.

• Computers and Concrete
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• v.16 no.6
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• pp.933-961
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• 2015

Damage by high-speed impact fracture is a dominant mode of failure in several applications of concrete structures. Numerical modelling can play a crucial role in understanding and predicting complex fracture processes. The commonly used mesh-based Finite Element Method has difficulties in accurately modelling the high deformation and disintegration associated with fracture, as this often distorts the mesh. Even with careful re-meshing FEM often fails to handle extreme deformations and results in poor accuracy. Moreover, simulating the mechanism of fragmentation requires detachment of elements along their boundaries, and this needs a fine mesh to allow the natural propagation of damage/cracks. Smoothed Particle Hydrodynamics (SPH) is an alternative particle based (mesh-less) Lagrangian method that is particularly suitable for analysing fracture because of its capability to model large deformation and to track free surfaces generated due to fracturing. Here we demonstrate the capabilities of SPH for predicting brittle fracture by studying a slender concrete structure (column) under the impact of a high-speed projectile. To explore the effect of the projectile material behaviour on the fracture process, the projectile is assumed to be either perfectly-elastic or elastoplastic in two separate cases. The transient stress field and the resulting evolution of damage under impact are investigated. The nature of the collision and the constitutive behaviour are found to considerably affect the fracture process for the structure including the crack propagation rates, and the size and motion of the fragments. The progress of fracture is tracked by measuring the average damage level of the structure and the extent of energy dissipation, which depend strongly on the type of collision. The effect of fracture property (failure strain) of the concrete due to its various compositions is found to have a profound effect on the damage and fragmentation pattern of the structure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.4
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• pp.236-243
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• 2013

Offshore wind turbines has to be proved against accidental events such as ship collision. In this study, ship collision fragility analysis of offshore wind turbine is done. Dynamic collision analysis is accomplished by considering soil foundation interaction and fluid structure interaction. Uncertainties due to ship weight and speed, angle are also considered. By analyzing dynamic response of offshore wind turbine, fragility curves are obtained for different damage levels. They can be used for restricting boat speed around the wind turbine and allowable size of the boat for inspection and for other purposes. Results of the fragility, it was confirmed fragility of collision speed of bulk ship of 30,000DWT and 850ton barge ship.

• Journal of the Korean Institute of Navigation
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• v.25 no.4
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• pp.417-422
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• 2001

Every ship might be exposed to collision, grounding and/or various accidents. They may make some underwater holes on the hull. An underwater damage would cause her loss of buoyancy, trim, and inclination. Although a ship has some provisions against these accidents, if the circumstance is serious, she would be sunk or upsetted. Because of varieties of type of accidents, one could not prepare all of them. Many subdivision could prevent them, but it is difficult to realize it due to rising costs. This paper deals with physical phenomena of sinkage and an application on box type ship, and some results are earned as follows； 1. sinkage speed up to the level of the damage hole is increased proportionally, and is decreased proportionally after filling the level. 2. the curve of draft shows cup type of second order polynomial up to the damage hole level, and shows cap type of second order polynomial after filling the level. 3. if damage occurs beneath half of the draft, changes of head and displacement, and sinking speed follow almost straight lines. 4. by careful observation, sinkage speed could be predicted.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.566-572
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• 2013

In this study, a collision simulator for rolling stock that considers the plastic deformation of the car body and the dynamic characteristics of a coupler system was developed using Matlab/Simulink. Normally, a coupler system has functions for both connecting the individual car bodies and absorbing the impact energy. A coupler system is composed of a rubber buffer, hydraulic buffer, and deformation tube elements. The coupler system should protect the car body and prevent damage when the shunt speed is less than 10 km/h, which is the regulation speed based on the safety rule for rolling stock. However, if the shunt speed is greater than 10 km/h, a car body is plastically deformed. Therefore, the modeling of the plastic deformation of a car body should be included in a simulator. This collision simulator can provide the design parameters for a coupler system and car body.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.65-71
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• 2008

In many cases, open-type plate breakwaters use plates with multiple holes; the holes serve as energy dissipaters and weight reducers. Because of the multi-holes configuration, stress concentration should be considered during the design process. Among several design loading conditions, the loads from a possible collision with a man-made vessel or other unexpected events many damage a multi-perforated steel plate. In that case, the structural behavior of a multi-perforated steel plate is quite significant, and is not well understood. This study presents a collision analysis for a multi-perforated steel plate. First, four different perforation topologies (three with circles and one with squares) were selected to investigate the effect of different hole shapes on the structural response. Second, the wave force at a specific site was calculated and loaded onto a steel plate as a static load. The static stresses were used for reference values. Third, two rigid body impacters (cubical & cylindrical) were applied to the steel plates to investigate the transient stress responses. In addition, two different impacting angles ($45^{\circ}\;&\;90^{\circ}$) were selected to investigate the angle effect. From the collision analysis, the significance of the transient stresses was emphasized.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.236-242
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• 2018

Damage due to ice collision is the most serious threat for the structural safety of ships operating in arctic region. Since such hull damages are usually caused by the collision of floating ice at excessive voyage speed of ships, the authorities responsible for the shipping at arctic sea are required to provide the speed limit for safe voyage, so-called safe speed. In countries near arctic ocean, such as Canada and Russia, empirical methods to determine the safe speed of ships based on their long experience of arctic voyage have been established and applied them in the real arctic navigation. However, in Korea, it is not easy to accumulate the arctic voyage experience and related technical database, so it seems to be a realistic approach to adopt a safe voyage speed estimating method in arctic sea based on the ice collision simulation technology using the nonlinear finite element analysis. The aim of this study is to develop a technique for estimating the safe voyage speed of vessels operating at arctic sea through the ice collision analysis, In order to achieve this goal, the standard procedure of the ice collision analysis is dealt with and example analysis was carried out and the results were considered. To investigate the validity of developed method, POLARIS system proposed by IMO was studied for comparison.

• Journal of Trauma and Injury
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• v.33 no.3
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• pp.181-185
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• 2020

Damage control surgery (DCS) is an abbreviated laparotomy procedure that focuses on controlling bleeding to limit the surgical insult. It has become the primary treatment modality for patients with exsanguinating truncal trauma. Herein, we present the case of a 47-year-old woman with liver, kidney, and superior mesenteric vein (SMV) injuries caused by a motor vehicle collision. The patient underwent DCS following resuscitative endovascular balloon occlusion of the aorta (REBOA). In this case report, we discuss the importance of priority setting in DCS for the treatment of multisystem damage of several abdominal organs, particularly when the patient has incurred a combination of major vascular injuries. We also discuss the implications of damage control of the SMV, perihepatic packing, and right-sided medial visceral rotation. Further understanding of DCS, along with REBOA as a novel resuscitation strategy, can facilitate the conversion of uniformly lethal abdominal injuries into rescuable injuries.

• 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.