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When an oil-spilling accident occurs at sea, such as Exxon Valdez Oil Spill (1989) and Oil Spill Off the West Coast of Korea (2007), it causes tremendous economic loss and environmental damages. To minimize these marine disasters, predicting the amount of oil-leaking is one of the most important things for the quick response and decision making in the early stage of the accident. In the present study, numerical investigation on the oil-leaking phenomena from a twodimensional damaged tank was carried out to predict the amount of the oil leaking from a leakage hole of a rectangular tank by using the PNU-MPS(Pusan-National-University-modified Moving Particle Simulation) method (Lee at. el., 2011). As a preliminary test to confirm the accuracy of the PNU-MPS method for the twophase problem and to investigate the influence of the gradient model, numerical simulations for the Rayleigh-Taylor(R-T) instability were carried out. By using the selected gradient model and applying high-order time scheme, i.e. 4th-order Runge-Kutta scheme, it was found that the simulation results became closer to the experimental ones (Kim and Lee, 2001), by which the oilleaking speed and Torricelli's factor relating the speed predicted by using the hydrostatic balance and the real leakage speed were measured and assessed.

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Two different configurations of rod-screw systems found statistically significant differences with axial gripping, pulling out, and fatigue failures. ST constructs improved fixation stability over TT constructs. It was concluded that ST configuration may reduce complications related to implantation.