The present invention relates to a mobile terminal using a proximity sensor and a control method thereof. The shutters include disc holders for holding the disc thereon with the center of the disc offset from that of the disc storage portion such that an outer side surface of the disc contacts with the sidewall of the disc storage portion at a position where the notch is located while the shutters are closed. Payload data is received from a host, and written to the flash memory in the order it was received. Group concept score vectors are generated for each of the spine groups by aggregating the concepts for that spine group. The method of the invention comprises forming a reaction mixture by combining molecular hydrogen, a first olefin, an optional second olefin, a diluent, and a vanadium-containing catalyst system at a sufficient temperature to allow formation of the polyolefin resin and initiating polymerization of the reaction mixture.