There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test.
The support test is different for each type. The support test, for a QC, is only that the child didn't provide more than half his own support. The support test for a Qualifying Relative is that the taxpayer provided more than half the relative's support.
In the case of a QC, it doesn't matter how much the person earned. What matters is how much he spent on support. Money he put into savings does not count as support he spent on him self.
The support value of the home, provided by the parent, is the fair market rental value of the home plus utilities & other expenses divided by the number of occupants.
If you're not sure whether you provided more than half your own support, The IRS has a worksheet that can be used to help with the support calculation. See: http://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf
Scholarship money is ignored in the support calculation (do not enter the scholarship amount or the expenses it paid for). Student loans are considered as the student supporting himself, unless the parent co-signed; then it's parental support.
In addition to all that, to qualify for the refundable tuition credit, half your support must come from working (your earned income).
For more specific advise, provide more details of your living situation.
