The Military Demarcation Line(MDL) is the complex symbol of great importance. It is one of crucial causes that have destroyed the ecological identity. Consequently, Korean literature has shown various symptoms according to every different period, embodying persistently the state of losing the ecological identity caused by the national division and its desire of restoring its original state, while it has gone through the periods of Cold War, post-Cold War, and digital age. Such novels as Choi In-hun`s The Square(1960), Park Sang-yon`s DMZ(1997), and Kang Hui-jin`s Ghost(2011) have many things in common, as they treat the tragic features caused by the national division, and share lots of controversial points in regard of reminding the ecological environment and the imagery of national division for every period distinctively. Yi Myung-jun in Choi In-hun`s The Square(1960) is the very picture of the first generation of the national division. He has given up every hope of both South Korea and North Korea which has lost the ecological identity, and commits suicide on the ship sailing towards the third country. But he is the character who has much significance in regards of presenting the ideal type of ``the blue square``, that is the symbol of the ecological identity. Bersami in Park Sang-yon`s DMZ, Yi Yon-wu`s son belongs to the second generation of the national division. He reminds us the fact that the tragedy of the Cold War is ongoing, through the searching view of an alien in post-Cold War period and its ``operant conditioning`` motif. The Kang Hui-jin`s Ghost takes place in the setting of the digital age. In this novel, a North Korean defector appears as a main character. He cannot find ``the blue square`` in reality and becomes absorbed into the digital game space. As a result, he becomes mentally deranged in the schizophrenic state on the boundary line between reality and virtual reality, while bearing his life very painfully. To him, virtual reality can be considered both alternative possible world and the negative environment which makes the reality worse. In this way, we can realize that all the three novels already discussed are related with the condition of the national division of Korea and the loss of the ecological identity. All the characters in these novels show the hope to move forward from loss to restoration under their own conditions in which they are placed, but consequently, their wishes are destined never to be fulfilled in reality.