Wow, I think it was an impressive essay. Considering that you are not a native english speaker, I think the essay was generally well-written. The content relates well to the question. However, there were several grammatical errors and also some sentence constructions that seemed inappropriate to me. Perhaps you have yet to reread and edit it?
Para1:
In my life, there is one unforgettable experience that I consider truly priceless.
In my life, there
was one unforgettable experience..
( The experience was in the past)
Para2:
The principal even cooked barbeques for the students. You would never see that happen in Korea.
The principal even
barbequed for the students.
(The term barbecue refers to the meat being roasted. So it doesn't make sense to say 'cooked, roasted meat'.)
Para4:
That two-month stay in Australia, totally transformed my thinking about "foreigners." I realized how terribly wrong and prejudicial I had been about others.
"Foreigners" and ' others', did you mean only Caucasians? I feel that you should be specific here. Because, from this context, I think it could only be referring to Caucasians.
My Australian experience had been so positive that I now had a burning desire to see more of the world and interact with other nationalities and cultures.
My experience in Australia had been so positive that I now
have ..
To be frank, I am only a secondary school student, myself. So the feedbacks I gave may not be entirely accurate.
Anyway, I am pretty touched by these 2 lines:
burning desire to see more of the world and interact with other nationalities and cultures.
I may be a Korean by birth but I now feel I am really a citizen of the world.
I think you have a fair chance of getting enrolled into the University if you presented this essay. This is definitely better than the personal statement I had sent to the college that have already accepted me. :D All the best to you! Thanks for your comments on my essay! :D