• International Journal of Highway Engineering
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• v.13 no.1
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• pp.185-195
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• 2011

Aircraft-related accidents cause mass casualties and major material damages. At present, runway-related accidents in our country account for 28% of all air accidents. Furthermore, internationally 33% of all air accidents is connected with runway. To prevent these accidents, FAA mandates the installation of aircraft rapid arresting system(ARAS) at the runway end safety areas which do not meet the FAA requirements. Even if the areas satisfy the conditions, FAA recommends the installation of ARAS to ensure the safety. In accordance of the international affairs, the domestic studies for ARAS are in progress and the legal formalities for domestic adoption of ARAS is under way. In this study, we analyzed the stopping distance, drag force, vertical force and tire penetration of runway overrun to assess the performance of ARAS reasonably by using two different kinds of analysis programs. The first is ARRESTOR program adopted by FAA, and the second is LS-DYNA which is available for 3-dimensional nonlineal dynamic analysis. As a result, analytically the stopping distances between two programs are similar. The drag force is rather different, but the tendencies are similar. Later on, the 3-dimensional simulation analysis considering various air-craft condition and properties of packaging materials is necessary. In addition, ongoing development of simulation analysis program is required for more accurate analistic results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.372-376
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• 2022

Since the ZnO varistor is a semiconductor device, the internal thermal distribution during the varistor operation is recognized as an important factor in the performance and deterioration of the varistor. For an optimal varistor structure design, the thermal runaway phenomenon during the varistor operation was interpreted using the Comsol 5.2 analysis program by a finite element analysis. The maximum temperature of the center measured in the cross section of the ZnO varistor was confirmed to increase as the temperature moved from the lower electrode to the center towards the upper electrode up to 572.6 K. The electrodes are thinned so that the influence of the Schottky barrier is not great. The heat gradient balance is determined to be improved when the electrode of the hybrid form is introduced. The thickness, density, pore distribution, impurity uniformity, and particle size of the ZnO varistor are required, and it is determined that the pyrolysis gradient will be improved regardless of the electrode thickness. When these results are applied to design the ZnO varistor, the optimal structure of the ZnO varistor can be obtained.