With increasing of interest in quad-rotor which has excellent maneuverability recently, a various types of multi-rotor aircraft was developed and commercialized, and there are many kinds of leisure products to be easily operated. In these products, the AR.Drone manufactured by Parrot has an advantage that it is easily operated by user due to the its internal stabilization loop in the on-board computer. Thus it is possible to design the unmanned UAV system easily by using this AR.Drone and its inner loop for the stabilization. For this advantage, KARI(Korea Aerospace Research Institute) has been developing the indoor swarming flight system by using multiple AR.Drones. For this indoor swarming flight, it is necessary that not only the position controller for each AR.Drone, but also the collision avoidance algorithm. Therefore, in this paper, the collision avoidance controller is provided for the swarm flight by using these AR.Drones.
The most design criteria and specifications in Korea utilized to ensure appropriate quality are based on process and prescriptive criteria determining materials, measure and methods. It has many problems including a loss of competitiveness resulting from inhibited creativity of the contractors. The performance-based specifications focused on final product are being proposed, but have difficulty in adapting to the architectural field. In this study the hybrid specification prototype for curtain wall construction was suggested. The specification framework was presented through analysis of linkage between the performance and prescriptive specification cases. Based on the survey with practitioners, the performance inspection process and the sample specification were developed by identifying the essential performance test timings. The applicability of the specification prototype was evaluated by interviews with experts. It was found that the prototype was active and a progressive supporting tool which could support to secure phased performance during construction as well as final performance.
The temperature-dependent tribological properties of brake discs for a train were examined in this study. The discs were produced using heat-resistant alloy steel, which showed different thermal conductivity after the heat treatments. A commercial brake friction material was used to evaluate the friction effectiveness, and the friction tests were carried out using a 1/5 scale dynamometer under various initial braking temperature conditions. The results showed that the tribological property of the disc was strongly affected by the heat treatment schedule. At low temperatures (below 250 o C), the friction coefficient increased as a function of disc temperature, indicating that frictional heat increased the adhesion between the disc and pad. In addition, fade was observed at high temperatures (above 250 o C); it was pronounced in the case of the disc with low thermal conductivity. The different fade resistances observed in the discs with different heat treatment schedules appear to be influenced by microstructural changes such as carbide redistribution occurring during the heat treatments, which affected the thermal conductivity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.