SEOUL, March 26 (Yonhap) -- Some 6 percent of grade school and university students in Seoul are addicted to their smartphones, with women three times more dependent on their devices than men, a survey showed Tuesday. According to the survey of 1,447 primary, secondary and university students residing in the capital city, 5.9 percent turned out to be addicted to the mobile device. By gender, the addiction ratio for female students came to 8.3 percent, about three times higher than the 2.8 percent of male students, it showed.