OAK (Open Access Korea) hosted by National Library of Korea is the national portal of institutional repository participating universities, public institutions, researches, and businesses. OAK has used OAK metadata based on DSpace to build OAK portal, and could not accommodate all the metadata elements that participant institutions wanted. Therefore, OAK could permit each institution to expand its metadata for its own appropriately. But this brought into missing data in harvesting data from IR member libraries, and developing redundant, disordered and inappropriate elements without device managing elements such as metadata registry. For solving these problems, this study is to suggest the OAK application profile through analyzing the metadata elements of member libraries and comparing metadata of the representative case such as DSpace, Eprints, BEPress, ETD-db, and dCollection.