The disclosure relates to an artificial intelligence (AI) system that simulates functions such as cognition and judgment of the human brain by utilizing machine learning algorithms such as deep learning and its applications. In particular, the disclosure provides a method of controlling data input and output of a fully connected network according to an artificial intelligence system and its applications, the method including receiving, from a learning circuit, an edge sequence representing a connection relationship between nodes included in a current layer of the fully connected network, generating a compressed edge sequence that compresses consecutive invalid bits among bit strings constituting the edge sequence into one bit and a validity determination sequence determining valid and invalid bits among the bit strings constituting the compressed edge sequence, writing the compressed edge sequence and the validity determination sequence to the memory, and sequentially reading the compressed edge sequences from the memory based on the validity determination sequence such that the valid bits are sequentially output to the learning circuit.