It looks legit, but his spec sheet does indicate that there are problems with commercialisation. http://www.superconductors.org/276K.htm indicates how to reproduce and what results to expect. A regular freezer can sustain -5C to 5C. An ammonia freezer can go as low as -27C, so 3C is easy to hold.
And the fact that he has been known for good results in the past shows, at least to me that this is the real thing. But of course, always the skeptic in these kinds of claims. At least it's not cold fusion, yet ;)
And ammonia can go far lower than -27, it can easily go below -60c.
I see. Well I'll just wait for additional confirmation from the Great Leader's University of North Korea.
Which countries are currently working on their own versions of that project? Uh, North Korea and Iran.
You can be DAMN sure that some of the best scientific minds outside of western main-stream are at the moment toiling away in Iran and North Korea.
Contrary to this, the Iranians and North Koreans aren't working on anything new (at least not under the auspices of the nuclear energy/bomb project). So don't expect many Nobel Prizes to come their way.
They're rehashing a tried and true path, with a lot of information (both in the public domain, along with probably a good deal of stolen classified material) available to them that the members of the Manhattan Project did not have.
That isn't to say that there aren't any brilliant Iranian and North Korean physicists working on the project. I'm sure they've got the cream of the crop in Iran and North Korea. But just because they're working on this doesn't make them world class physicists.
It means that the claims should be taken seriously, since he's competent in the field, but he might have made a mistake somewhere (even though, from what I understand of his report, the results seem clear. But since I'm not even a physicist, my opinion is worth peanuts).
The peer reviewed confirmation of his previous discovery can be found here: http://www.superconductors.org/SDARTICL.pdf.