Methods, apparatus, and computer readable media determine a transmission rate. The internal clock signal is used for a synchronous operation of an internal circuit. Further, the loading effect andor fogging effect can be easily calculated because the above-described method can be realized as a computer program and the computer program can be included in an exposure tool, thereby enabling exposure based on a corrected value. A coordinated drive system provides for both upwardly and downwardly breaking or jointed orientations of the two sections in various inclined and tilted positions. A system for providing an on-demand interactive magazine comprises a receiver operable to receive a magazine and data associated with the magazine, a receiver operable to receive at least one broadcast, a storage device, and a processor configured to use the data to store portions of the broadcasts and present the magazine to a viewer. The concave part cover comprises: a top plate 11 for covering the concave part; and a pair of pressing parts 12A and 12B extending from the top plate 11 and pressing side walls 52A and 52B of the concave part when the pressing parts 12A and 12B are inserted into the concave part.