• 한국자동차공학회논문집
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• 제18권3호
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• pp.95-103
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• 2010

This paper presents a simulation model of a double-acting high-speed pneumatic cylinder with a relief valve type cushion mechanism. The model predicts piston motion, mass flow rate, pressure and temperature time histories of cushion chamber. Of interest here is to investigate the cushioning effect of varying the piston and piston-rod diameter, cushion ring diameter and length, and stoke in cushion mechanism. As a result, this cushion mechanism is found to be adequate under high-speed driving of pneumatic cylinders. The simulation model proposed here will be very useful to analyze the dynamic characteristics and to improve or design the better cushion mechanism in high-speed pneumatic cushion cylinders.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.928-942
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• 2020

The pressure responsiveness property of a skirt-cushion system, which is closely related to the overall performance of Air Cushion Vehicles (ACVs), has always been the difficulty and challenging problem involving cushion aerodynamics and flexible skirt dynamics. Based on a widely used bag and finger skirt-cushion system, the pressure responsiveness properties are investigated numerically. The physical process and mechanism are analyzed and a numerical method for evaluating the pressure responsiveness property is proposed. A cushion-skirt information communication platform is also presented for interchanging the force and the skirt configuration between cushion aerodynamics and flexible skirt dynamics. The pressure responsiveness of a typical skirt-cushion system is calculated and the results demonstrate that the pressure responsiveness property helps alleviate the influence of the cushion height changing on the overall performance of ACVs. Finally, the influences of skirt geometrical and cushion aerodynamic parameters on the pressure responsiveness properties are discussed systematically, giving insight into the design of skirt-cushion systems.

• 대한조선학회논문집
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• 제47권5호
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• pp.697-702
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• 2010

A WIG(Wing-In-Ground effect) craft flies close to the water surface by utilizing a cushion of relatively high pressurized air between its wing and water surface. This implies that when one designs such craft it is important to have lightweight structures with adequate strength to resist external loads with some margins. To investigate this requirement, this paper deals with the structural analysis of the bottom plate of small WIG craft having a design landing weight of 1.2-ton. As building materials for the WIG craft, pre-preg carbon/epoxy composites are considered. The strength information of the bottom plate is obtained using the first-ply-failure analysis in conjunction with a mid-plane symmetric laminated plate theory. As a result, the first-ply-failure location, load and deflection of the bottom plate are obtained. The calculated strength information is compared with the water reaction load for the bottom plate of seaplanes considered when they land on the water surface -the same fluid-structure interaction mechanism as that of WIG craft. In the calculation of seaplane water reaction load information, the rules shown in FAR(Federal Aviation Regulations) Part 25 are used. Through the comparison, the structural integrity of the bottom plate for the WIG craft is checked.