What do you even write in the study plan?

They do read it, but not the way you are imagining. Nobody is grading your prose. The officer is checking one thing: does this person's story hold together.

One page is enough. 400 to 600 words. Longer is not better.

A structure that works:

1. Who you are now. One short paragraph — what you studied or what you do, and where you are in life. Two or three sentences.

2. Why Korean, specifically. This is the paragraph that matters. "I want to learn Korean" is not a reason, it is a restatement. A reason is: my company works with Korean suppliers and I handle that account; I want to apply to a graduate program in Seoul and need TOPIK 4; I have been self-studying for two years and hit a ceiling.

3. Why this school and this program. One or two sentences. Naming the school and the level you expect to start at is enough to show you did not apply at random.

4. What you plan to do after. This is the second paragraph that matters, because it answers the unspoken question — are you going to leave. Returning home with the language, applying to a degree program, using it professionally. Any concrete plan is fine.

5. How you are paying for it. One sentence, consistent with your bank certificate.

The two mistakes that cause problems: contradicting your own documents (saying you will study two semesters when your funds cover one), and writing something so generic it could belong to anyone. A slightly plain, specific, honest page beats an eloquent vague one every time.

Write it in your own words. We review study plans for our students before submission, and the ones that need the most work are almost always the ones copied from a template.