An article has been successfully peer reviewed and published online but resubmitted in a society conference proceedings for presentation. Does such practice ethical or unethical?
Not for conference proceedings. But can be presented at a conference with the paper shared. This is good as a poster. Especially if the paper was published as closed access. It improves the accessibility of the work done
We need to distinguish between "publishing a study" and presenting a "study". It is unethical to republish a work already published elsewhere. However, the work can be presented in an academic forum and even quote the work as ref. It can even be presented as a poster at a conference, but definitely not republishing it in any academic document.