If the publisher makes the full-text paper accessible for free, you have no problem in publishing the same in RG and if you ask them this question, they will tell to do it or not.

Ethics and copyright law work together. If you did not assign the copyright, you can legally republish.  If you don't, you cannot without consent of the assignee of your original work of authorship.  Ethics define what is respectful to your colleagues and clients.  Citation of the published work in the IEEE journal would identify it and promote all.  

Even if you do not own the copyright, you have a legal right (under U.S. law) to publish an extract or to paraphrase it.  This right of "fair use" can be abused, so consider all the circumstances.

I practice law in the fields of technology, international business and innovation.  Good luck!

Yes.

It shouldn't be

Generally we put full text. However, it may cause loss to publisher as articles which they were likely to sell at 10-30 dollor will be freely available.  Whether to put matter is debatable publisher will never agree to that.

Here's a modest proposal to authors:

• Make a deal with the publisher to identify who owns the copyright to article and what reserved rights the non-owner has.
• Author should have the right to republish the title and the abstract freely, with pointing to the publisher.
• If the publisher does not provide the article upon request by a reader at a reasonable price, the author can do so without accounting.
• Author can use for teaching students.
• Author can use extract of up to XXX words
• Author can put on his /her website after 6 months (or some agreed time).
• Author should consider selecting publicatoin based on best audience and best services to all, and take the article elsewhere if no reasonable deal.

In a world of online publishing e-book self-publishing is good too, but generally not refereed.

if you are creative in research, be creative in PR!