Provided is an apparatus and method for estimating inverse channel of a repeater’s receiving channel, which ensures stability and causality by generating a time-domain filter coefficient having information on an inverse channel of repeater’s receiving channel from a signal transmitted from a main transmitter or another repeater. A system in accordance with one embodiment of the invention includes a display medium coupleable to a flight manager, with the flight manager configured to receive and direct instructions for automatically controlling aircraft functions at a future time during flight of the aircraft. The server system receives purchaser information including identification of the purchaser, payment information, and shipment information from the client system. The manufacturing process subsequently locates the heat exchange unit filled with the hydrogen storage alloy in a cylindrical tank and narrows both ends of the tank to form joint openings.