Korean people have two concepts of “nationalism;” one is “state-nationalism,” other is “ethnic-nationalism.” Korean people believe that they are a “single nation” and the reasons are related to Korean history. The Japanese colonial period was an important time for making the Korean nation's identity. The Korean nation's big assignment was “to overcome colonialism” and the difficulty is that this “history problem” is still running though East Asia.
Furthermore, under Park Chung Hee, the notion of the Korean nation was remade by Park. Park constructed Korean nationalism in order to make a rich and powerful country. The Korean public people mobilized to build the modernized state through the 1960s-1970s.
Nationalism still affects Korean society strongly. But it is not the same as Park Chung Hee's nationalism. The Korean public reactions about the “nation” and “nationalism” are variable depending on issue these days. Although the “nation” and “nationalism” are difficult to explain, people make the notion of “nation”/ “nationalism” and they could well live in “delusion”. Therefore, Korean people want to accept that their true nation is a “single nation” in order to protect the Korean nation and the country.