Travel useful links:

Visit Korea: http://english.visitkorea.or.kr
Koroot (Guesthouse for Adoptees): http://koroot.org/eng/main
K-ETA (K-ETA is Korea Electronic Travel Authorization): https://www.k-eta.go.kr/
K-ETA is not required for Belgian citizen during the period 01/04/2023 till 31/12/2024: https://www.k-eta.go.kr/portal/board/viewboarddetail.do?bbsSn=149899
2023 OKFriends Homecoming Youth Camp, OKF program summer 2023 for young people 18-25 at university, 1 week in Korea in July 18 – July 25 (7 nights, 8 days) -OR- August 1 – August 8 (7 nights, 8 days), completely free for adoptees and children of adoptees (flight, hotel, transportation, meals). ~~register rapidly~~, more info here (registration is closed now, but similar summercamps are organized each year)
Where to eat in Seoul?: seouleats.com
Website to find a shared house in Korea
https://www.thecomenstay.com/
(cheaper than airbnb for long term stay, for students)
Website to rent a room in a host family https://www.homestay.com/ (cheaper and interesting for people who want to exchange with local people)
Information about transportation in Korea: https://www.facebook.com/unboldecoree/posts/650378920448901