A South Korean doctoral candidate in the U.S. has developed a new method to detect underground nuclear tests using the Global Positioning System (GPS).

Ohio State University said on its Web site that Park Ji-hye, a doctoral student at the university, has presented a new model detecting the sites and the times of underground nuclear tests by means of the GPS.

Park reportedly figured out the site and time of a nuclear test by detecting changes in the ionosphere’s atmospheric ion density using a GPS satellite around the time of the underground test.

She unveiled on Thursday the new method at the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) meeting in Austria.