This question already has an answer here:
some years ago (2007) I have published a paper in a conference as a poster paper. Now I want to send it to a journal and change the affiliation, or maybe some minor changes. I didn't see any policy about a previous published paper in a conference, however there is a policy as the following:
The submission has not been previously published, nor is it before another journal for consideration (or an explanation has been provided in Comments to the Editor).
Could I send my paper to this journal?
Is it a normal thing to first publish a paper in a conference and then trying to send it to a journal?