According to what we were able to translate from the site and estimate from the images, the formation's diameter must range between something like 150 and up to 200 meters (450-600 ft) in diameter.
So far this formation is the very first crop circle documented in South Korea.
According to the photographer "98papa" it felt different entering the flattened areas. He described his sensation as like and electrical current and weakening.
Most of the Korean text on the site does not give further insights about the crop circles itself but gives a roundup of the crop circle phenomenon's basic background and history.
So far we have no further information about this crop circle formation and we even do not know it it is a crop circle in the classical sense - but will update as soon as we learn more...