If you look on Wyeast's website, both of those strains have low flocculation, meaning it will stay in suspension longer than strains with high flocculation. More time, cold crashing, and using gelatin will all help with clearing your beer. If you have clumps of yeast on top of the fermented beer (yeast rafts), then simply shaking the fermentor or pushing them down with anything sanitized will get them to sink.