Is it ethical/legal to publish Master thesis manuscript as a journal paper? I have submitted my Master thesis manuscript to the university library. It is completely new work (never published before to any journal or conference). Now, I want to submit my Master thesis to a journal (as a paper) without modifying it much/anything. Is it ethical/legal to publish your Master thesis manuscript as a journal paper? Should I mention this to the editor of the journal? Because, in the journal guidelines, it says: we accept the manuscript only if it is not published before to any journal or conference. It does not mention anything about other publication sources (like: Master or PhD thesis submitted to the university library). Will I face any problem in future if I do so?

PS: I am thinking to submit it in IEEE Transactions on Computers journal. I talked with the university librarians. They told me they do not have any problem if it is published elsewhere. They just keep a copy in the university library (including online library - which I can also keep 'private'). I am asking if the journal has any problem or not? For my university, it does not really matter (since I have already given the manuscript to them and they have accepted it). My university is in Republic of Korea.
It is perfectly Okay to make a paper out of a master's thesis. Many aspiring PhD candidates do.

However, an MSc thesis is typically 50-100 pages long. A paper is (in a dense journal format) typically 8-12 pages long. Let's make a generous estimate for 20 pages in the thesis layout.

So either your thesis is very thin, or the journal is very generous, both of which seems unlikely.

Next issue is that you write a thesis in a very different manner than a research paper.



Hence, you would definitely need to rewrite the paper. And you have one issue less to worry about. The copyright might still be a concern for figures, for example, but from your comments I recon that this is not a problem. (It should not have been one, but it was proper to check before.)