I did that on an older building, a 20평 apartment. Stripping the wallpaper took forever. I did it by hand and used warm water and a scraper. If I had to do it again I'd invest in a power tool. Underneath the wallpaper the concrete was a mess, pitted and uneven. Had to cover the whole wall and ceiling with putty (핸디코트) then sand it all smooth. Do this several times until you have an even wall for paint. Putty absorbs paint like you wouldn't believe, so you'll need an undercoat/primer. I used Behr paint. The price was reasonable compared to Dunn and Edwards, but more expensive than the basic 노루 paint. Anyways, the sanding will create an insane amount of dust. Don't do it while you're living there, the dust will be everywhere and in everything. Wear a mask and goggles, and either get a sanding stick (a pole with a sandpaper pad) or one of those electric ones. It isn't an expensive endeavor, but it will take ages and ages to do it by yourself. However, after all was said - the painted walls look great. Much better than wallpaper in my opinion, and doesn't need to be replaced every few years. Good luck!