I discovered that www.tuicool.com systematically copies content of my site - in cases I submitted the link to DZone. A short check showed that they copied 16 sites from Software Engineering Candies. Maybe they copied also your content! For my copied sites I submitted immediately a deletion request to Google's DMCA-Dashboard and strongly recommend you to do the same.
Duplicate content may lead to a reduced PageRank of your site (see Webmaster Tools - Duplicate Content) and is something serious. I spend a lot of time to write original and high value content. Stealing this is not a trivial offense. At least there should be some added value in the article. These guys from www.tuicool.com are just thieves - they copy all without added value.
Figure 1: Stolen Content
Figure 2: Original Content