• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.448-461
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• 2019

Changes in gravity and buoyancy of a Full Ocean Depth Autonomous Underwater Vehicle (FOD-AUV) during its descending and ascending process must be considered very carefully compared with a Human Occupied Vehicle (HOV) or a Remotely Pperated Vehicle (ROV) whose activities rely on human decision. We firstly designed a two-step weight dropping pattern to achieve a high descending and ascending efficiency and a gravity-buoyancy balance at designed depth. The static equations showed that gravity acceleration, seawater density and displacement are three key aspects affecting the balance. Secondly, we try our best to analysis the gravity and buoyancy changing according to the previous known scientific information, such as anomaly of gravity acceleration, changing of seawater states. Finally, we drew conclusion that gravity changes little (no more than 0.1kgf, it is impossible to give a accurate value). A density-depth relationship at the Challenger Deep was acquired and the displacement changing of the FOD-AUV was calculated preciously.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.142-147
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• 1995

Dynamic characteristics of current collection system is one of the major factors which decide the performance of high speed train. To find good design parameters of the current collection system design guide is prepared through the engineering analysis in this study. The analysis starts from the statics of catenary system which results in the sinusoidal variation of stiffness, which is inherently nonlinear Mathieu equation. Simple physical models of rigid trolley wire and Mathieu equation are considered. To simulate the dynamic response of current collection system, numerical integration based on central difference method and modal analysis are presented. The calculated results of central difference method show superior to those of Euler based algorithm.