Need suggestion on simultaneous submission in journal and conference Is it correct to submit a revised version of a paper to the same journal while some application part of the paper is under review in a conference?  

I have received a request for revisions on a journal paper, and am thinking to submit some part of it to a conference. I can't wait for the conference decision, as that will cross the journal revision deadline. Therefore, my question is can I submit it to the same journal while the paper is under review in conference.

The conference and journal version have similarities, but they are significantly different at the same time.
It sounds like you've gone in the wrong order, here.  In computer science, it is common practice to initially publish a work in a conference, then the follow it by an extended version in a journal, which is more thorough and takes into account all of the feedback from the conference and advances during the time since the conference version was completed.

Going the other way, however, strikes me as unethical and a form of self-plagiarism.  You have already produced a journal-scale paper, and mining a smaller conference paper out of it is just double-publication.  Now, in certain cases a conference might accept this if explicitly declared (there are some conferences that have a special track for reports on journal publications).  If the conference expects original work, however, you cannot ethically submit your paper to the conference.