Journalによりpolicyが異なるので、投稿先journalのpolicyを調べる必要がある。

例えば、IEEE Transactions on Wireless Communicationsでは、”The conference version(s) should be cited when submitting the journal paper in two places: (i) in the Manuscript Central field requesting this information, (ii) in the journal paper itself. There does not need to be a summary explaining the differences/similarities, since they are assumed and allowed to be quite similar, simply the existence of such a paper must be acknowledged.”と書かれている。

http://www.comsoc.org/twc/conference-vs-journal-papers