A method of improving the thermoelectric figure of merit of a high-efficiency thermoelectric material is disclosed. The method comprises receiving identification data for a player and displaying representations of game play of the game, wherein at least one character is depicted as one or more graphic objects. The vertical multitubular heat exchanger includes a shell extending in a vertical direction, an upper tube sheet and a lower tube sheet respectively disposed at the upper portion and the lower portion of the shell, and a plurality of heat exchanger tubes whose outer circumferences of both ends are respectively fixed to the upper tube sheet and the lower tube sheet. The low energy notification message has at least one destination address to which the low energy notification message is to be sent.