The agency issued an alert just after 8 a.m. Friday, Yonhap News Agency reported.
Solar flares, a temporary local increase in brightness, release large amounts of energy that increases the ionization of Earth's upper atmosphere. That disrupts shortwave, high-frequency transmissions and can also affect satellites and cause problems for astronauts.
The U.S. Space Weather Prediction Center said the flare was the brightest so far this summer, Space.com reported.
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