드림사이드 should be translated to "dream realm", shouldn't it? I feel like "dreamcide" and "dreamside" are both bad translations. But if we're going for a literal translation then dreamside should be closer...

Dreamcide is official English translation by Tapas

Dreamside also shows on this url
http://webtoon.daum.net/webtoon/view/dreamside

Sorry, I don't have opinion on translation.