What constitutes "Korean-ness"?

Throughout the entirety of Our School, the question of what it means to be Korean is a clear and prevailing theme. What constitutes "Korean-ness"? Is it one's ethnicity or the nationality that one holds? Or is it both? And when it comes to the diasporas, at what generation does one's self-identification of being Korean end? If you no longer speak the language nor retain any of your mother/father-land's culture, then can you still identify as being Korean? 

While watching Our School I couldn't help but feel for the students as I saw them struggle with their own self-identification throughout the film. From the beginning of the film, we saw students reveal how they were at many times embarrassed and ashamed to be Korean while living in Japan. They disclosed how they sometimes wished that they were born Japanese. And as similarly described by Sonia Ryang, the students are like the diasporas that are “unable to trace their origins to one country, since they originate from various parts of an entire continent that is now divided into many formed nations” and they as such are further conflicted in their own self-identification. And the generally antagonizing Japanese environment definitely did not make it easy for the Korean students to be proud of their own heritage. But as the film progressed, and as we saw the students visit their fatherland, we observed the students' new-found pride in and identification with their roots. 

But what then really constitutes the students' "Korean-ness" that they are able to be proud of? Is it the fact that the female students wear traditional Korean clothes that makes them Korean? Is it the fact that they speak the Korean language that makes them Korean? And if they were to forego all these things would they still be Korean? 

Another point that I would like to bring up is the notion that South Korea was denoted the "motherland" while North Korea was denoted the "fatherland". What is the reason behind the chosen gender-roles applied to each nation? Is North Korea more "masculine" in its history and politics while South Korea is more "feminine"? These are all questions that came to mind while I watched Our School.