US Patent 9190139 Memory and memory system including the same

A memory may include a plurality of word lines, one or more redundancy word lines for replacing one or more word lines among the plurality of word lines, a target address generation unit suitable for generating one or more target addresses using a stored address, and a control unit suitable for sequentially refreshing the plurality of word lines in response to a refresh command which is periodically inputted, refreshing a word line selected based on the target address when the refresh command is inputted M times, and refreshing the one or more redundancy word lines whenever the refresh command is inputted N times, wherein the M and N are natural numbers.