
.....
It's TB (Tuberculosis) and it's prevalent in Korea in the past.. Considering its symptoms like shortness of breath, fatigue and weakness, it's probably TB.
http://m.koreabiomed.com/news/articleView.html?idxno=6624
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(55)93403-6/fulltext
http://m.koreatimes.co.kr/pages/article.amp.asp?newsIdx=264265
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6940379/
I miss traveling! Hopefully, this pandemic soon..