unsupervised learning in medical systems and intelligent systems?
Expert systems rely on knowledge "extracted" from human subject matter experts (e.g. a team of physicians). They then use this knowledge to make prediction about the data (e.g. if blood pressure > x then patient).

Your approach used properties of the dataset you worked on. The knowledge was in fact extracted from the data themselves. 

The second approach may or may not be compatible with expert advice. If your algorithm found that blood pressure was a good feature to split healthy people and patient, you will probably find experts agreeing. However, if your main feature comes from a combination of many variables (e.g. PCA) you may have trouble finding an expert validating your approach. 

So the way you could use your approach would be to team up with subject matter experts and make sure that you use only features that have a meaning for them (i.e. don't over-engineer data).