This is a place I know my friends have gone to. I need more info about it because I only went there once myself (ages ago), though I did walk by it everyday! From their online presence, it seems not to have a jjimjilbang area, so could be only bathing. Also, I would assume it is not open 24 hours, though there is not very much information online about it.
I was told that this place has a nicer sauna area than Hwang-so in neighboring Seongseo. Go find out, and report back. ^^
Yongsan Dong Bup-jo Building Samjeong Oasis
대구 달서구 용산동 230-21
Daegu, Dalseo Gu, Yongsan Dong 230-21
Wikimap of Samjeong Oasis