Who owns the copyright in my research publications?
JMU's IP Policy 1107 states "The 1976 Copyright Act (P.L. 94-553) provides that, when a copyrightable work is produced by one person who has been employed by another for that purpose, it is the employer and not the actual producer that is the copyright proprietor. At JMU, traditionally faculty members have been granted the copyrights in their works by the institution."
This means that, other than certain exceptions as listed in Policy 1107, researchers retain the exclusive rights to their research publications. Neither students, other faculty, nor the institution may infringe on those rights without permission.
However, Academic publishers have traditionally required that authors transfer (or "assign") their copyright to the publishers. It is becoming common for publishers to accept a "non-exclusive license" to publish academic work. In that case, you would retain the copyright and be able to make subsequent uses of your own work without permission.
Even if you transfer your copyright to a publisher, it is possible to retain some rights to make certain uses of your work. Read publication agreements carefully and be ready to negotiate with publishers. Otherwise, you may no longer be able to use your own work without seeking permission from the publishers.