Another possibility is applying for a working position in Korea. In this case, you should focus on your skills and strengths, explaining why you are the best person to travel abroad and work in Korea. Your desire to help, to teach, or to provide a unique skill-set are all potential topics. You should focus on yourself, not on preconceived notions or external information.
For a class, the essay should be more formal; focus on the qualities of Korea that you wish to experience, whether it be the culture, religion, or environment. Enriching your own experiences by visiting historical sites is a good way to research and learn about the history and culture, and this can extend into your wish to experience them personally instead of simply reading about them.