Am I allowed to use published research in building an industry project?
In general, research that has been published openly in the scientific literature is freely available for anybody to use and build upon.  As such, there is no requirement, either legal or ethical, to involve or notify the authors of the use to which you are putting their work.  

The exceptions to this are:


If there have been patents filed (which should be stated in a conflict of interest statement in a journal paper, but may not appear in a conference paper) you may be constrained by patent licensing if the patent actually gets granted (though that typically takes a number of years).
If you publish a paper yourself, then you are ethically required to cite their work.
If you think the users of the system would find it interesting/useful to know about its origins, you can include it in appropriate parts of the documentation.


Beyond this, of course, most people would be happy to learn that their work is being put to good use: if you decide to contact the authors at some point and tell them what you're doing, they'll probably be glad to hear it.