One fundamental problem here is the two of you have different definitions of what warpage of a rotor is. IDK if that Korean paper defined it, they should. But it sounds like their definition is similar to Clares, while Arlen says that warping has to be like a wavy, potato chip effect. Would seem to me that any change in the rotor away from it's true shape that causes problems could be called warpage. If you don't call it that, what would it be called? Deformation? Never heard anyone call it that.