Abstract: A cooperative caching method and apparatus for reducing data access time and data acquisition cost in a mobile communication system are provided. The cooperative caching method of a local base station in a mobile communication system using caches of base stations cooperatively connected with each other includes determining, when a request for data is received from a client, whether the data is stored in the cache of the local base station; sending, to a home base station, upon determining that the data is not stored in the cache, a request for the data; acquiring the data from one of the home base station and a server according to whether the data is stored in the home base station; and serving the data to the client.

Abstract: A cooperative caching method and apparatus for reducing data access time and data acquisition cost in a mobile communication system are provided. The cooperative caching method of a local base station in a mobile communication system using caches of base stations cooperatively connected with each other includes determining, when a request for data is received from a client, whether the data is stored in the cache of the local base station; sending, to a home base station, upon determining that the data is not stored in the cache, a request for the data; acquiring the data from one of the home base station and a server according to whether the data is stored in the home base station; and serving the data to the client.

Abstract: A method and apparatus for a sensor network having a plurality of reference nodes and a sensor node that enables the sensor node to compute a relative position through transmission range control and position mapping. In transmission range control, each reference node sends location information signals to the sensor node while varying transmission power. In position mapping, the sensor node forms a grid of vertical and horizontal lines corresponding to a square area defined by the neighboring reference nodes, extracts coordinates of intersections in the grid belonging to a shared region between areas covered by location information signals of various transmit power levels from the neighboring reference nodes, and sets the position of the sensor node to the middle points of the extracted coordinates. Each reference node sends a location information signal when a random backoff time expires after reception of a location information request signal.

Abstract: The present invention relates to an electric-field drive display device. According to one embodiment of the present invention, the electric-field drive display device comprises: a first substrate; a first electrode which is formed on the first substrate; a second electrode which is formed on the first substrate and is disposed in parallel with the first electrode; a drive partition wall which is formed on the first electrode and the second electrode and has a plurality of opening and closing holes; and a plurality of drive bodies which are disposed inside each of the opening and closing holes. Consequently, the electric-field drive display device according to one embodiment of the present invention can adjust the amount of light transmitted and so display the desired image by adjusting the positions of the drive bodies in the horizontal direction through the use of electrical force.