Did a little digging on the UNC Registrar's website and found this:
First, you must establish domicile in North carolina with the intent of becoming a permanent resident or satisfying any of the below. I would imagine completing your internship in the summer would count for UNC and show intent, thus allowing you to apply for in-state tuition for year two.
The following factors, if actually present in the case, would tend to support a finding that the student did intend to establish domicile in North Carolina:
The student moves to North Carolina for a significant period of time prior to enrollment in an institution of higher education, during which period he or she is employed or engaged in other substantial activity unrelated to education pursuits; the possible inference is that educational pursuits were not the exclusive motivation for coming to the State or perhaps the continuing sole motivation therefore.
The student comes to North Carolina with a spouse and/or children, either significantly before or immediately coincident with his enrollment; the possible inference is that the student is the head of an independent household who is establishing a family home in this State.
The student purchases a residence in the State where he or she resides, with or without other family members (i.e., spouse and/or children); the possible inference is that the student has put down roots on a permanent basis and, incident thereto, is engaged in educational pursuits.
The student does some or all of the following acts in North Carolina: registers to vote; files income, personal property, or real property tax returns; registers or licenses a motor vehicle; acquires a driver's license; owns real property; is employed; maintains membership in social, fraternal, religious, or other organizations; maintains banking accounts.