Abstract: A printer includes: a transfer unit configured to transfer printing paper in a printing direction; a printing unit configured to print information on transferred printing paper; a detection unit installed to face discharged printing paper on a printing paper discharge portion side, and configured to acquire measured values by detecting light while printing paper is transferred or when the transfer of printing paper is stopped; and a control unit configured to collect measured values of the detection unit while printing paper is transferred, to calculate a reference value by using the collected measured values, and to determine whether printing paper has been removed by comparing the calculated reference value with a measured value acquired by the detection unit when the transfer of printing paper is stopped.

Abstract: An encryption method for compressed video is provided. The encryption method includes the steps of confirming a partial bit stream included in a compressed video, and selectively using a lookup table—the lookup table storing encryption information, which is needed for each encryption of a plurality of bit streams, at addresses of patterns respective to the plurality of bit streams—based on a result of the confirmation and encrypting the partial bit stream.

Abstract: An encryption method for compressed video is provided. The encryption method includes the steps of confirming a partial bit stream included in a compressed video, and selectively using a lookup table—the lookup table storing encryption information, which is needed for each encryption of a plurality of bit streams, at addresses of patterns respective to the plurality of bit streams—based on a result of the confirmation and encrypting the partial bit stream.

Abstract: An event detection method using frame grouping according to time and an apparatus therefor are provided. The event detection method includes generating a plurality of images by successively capturing objects using a plurality of frames, wherein the plurality of frames are grouped into a plurality of groups based on whether the plurality of frames have the same or similar amounts of exposure, grouping images generated with frames corresponding to each of the plurality of groups, and determining whether a previously defined event occurs using the grouped images.