a shape a color or a size if the detected mark represents an incorrect direction in operation 304 a current printing direction may be rotated by 180 u00b0 in operation 305 the control module may determine an ultimate printing direction in more detail if the detected mark represents a correct direction the current printing direction may be determined as the ultimate printing direction if the detected mark represents an incorrect direction the current printing direction may rotate by 180 u00b0 according to an exemplary embodiment of the present general inventive concept if it is determined that the paper is flipped over the wrong way the control module may flip and re feed the paper in operation 302 however according to an exemplary embodiment of the present general inventive concept an error message may be output via a user interface and then the printing operation may be terminated fig4 a is a diagram illustrating a sheet of paper and a mark according to an exemplary of the present general inventive concept fig4 b is a diagram illustrating a printing operation table according to an exemplary embodiment of the present general inventive concept in fig4 a and 4b a mark is recorded in only one region of paper as described in relation to fig2 referring to fig4 a a mark is recorded in only an upper region 401 of a printing surface 400 a control module has the printing operation table illustrated in fig4 b in advance and may process a printing operation based on whether the mark is detected from the sheet of paper in more detail if the mark is detected the control module may control a printer to perform the printing operation in a direction in which the sheet of paper is.