Only 10% of Chungcheongbuk-do native speaking teachers have teaching certificatesYou can pretty much set your watches by these kind of reports; they come out several times a year. The official quoted in the last paragraph should likely note that generally a diploma from one of the 7 countries alone won't get you an E-2 visa, though I suppose, since one school had a teacher from India, that there are some loopholes there. Also worth pointing out is that if there are 315 teachers in 408 schools, there are quite a few working in more than one school (a friend working in Gongju years ago worked in 3 or 4 different schools a week).
It's come out that among native speaking teachers placed in Chungcheongbuk-do elementary, middle and high schools, only 10% have teaching certificates.
According to materials from a Chungcheongbuk-do education office administrative inspection on the 12th, as of April of this year, out of 470 elementary, middle and high schools, 408 schools (86.8%) have 315 native speaking teachers placed in them.
This is an increase from last year, when 371 schools (78.3%) had 283 native speakers placed there.
However, among the 344 native speaking teachers placed in schools, English experience centers and other provincial education office institutions this year, no more than 36 native speakers (10.5%) have teaching certificates.
As well, this year among native speaking teachers the number of those who had not completed the course for a TESOL foreign language instructor certificate reached 207 (60.2%).
Regarding this, an official from the provincial education office said, "There is no problem selecting them as native speaking teachers as long as they have a diploma from one of the 7 countries which uses English as the mother tongue, such as the U.S. or England"
Also on this topic are Scroozle's thoughts about foreign teachers in the public education system in Korea (via Roboseyo).