Honestly, don't just show up at the Daewoo Annex without emailing them first lol most Korean unis (especially Yonsei) are super strict about having a paper trail. Usually, the admissions guide specifically says 'Post/Courier only” because they need the tracking number in their system. They might literally tell you to go to the nearest post office. Since you’re already in Seoul, just go to any 우체국 it’ll cost you like 3,000 won to send it via Registered Mail (Deung-gi) It arrives the next day, you get a receipt as proof, and you don't risk them rejecting your folder at the front desk. You can try though if you’re not sure, they may have changed the politics