1. A method of estimating a motion of a video in a video system, the method comprising: estimating an occlusion area by using a pattern map which results from the detection of an object or areas having a periodic characteristic in an input video; removing from a motion vector field a motion vector which corresponds to the estimated occlusion area according to a result of a previously performed motion estimation and outputting remaining motion vectors as first candidate motion vectors; collecting motion vectors from the motion vector field which correspond to an area of interest in the input video, detecting a representative motion vector which represents the collected motion vectors, and respectively comparing first candidate motion vectors with the representative motion vector; removing a first candidate motion vector having a difference in a weight value which is greater than a first threshold value from the representative motion vector and outputting the remaining first candidate motion vectors as second candidate motion vectors; and performing a motion estimation operation by using the second candidate motion vectors.