In 21st century, Korean pop music became one of the popular music genres in the world, particularly in Asia. Interestingly, many people looked Korea as "closed country" before the appearance of new term K-POP. Introduction of new styles or structures of music groups and new styles of songs was enough to attract listeners (of music) throughout the world. For example, one song Gangnam Style was popular enough to have more than two-hundred millions of views in Youtube. Also, one idol group Girls Generation, which is composed of nine Korean women singers, is enough to be extremely popular in Southeast Asian countries and Japan in late 2000s and early 2010s. It will be great opportunity to learn more about how musics from small country affect people throughout the world, global media, and global trend of music.