Ŭiju is a kun, or county, in North Pyongan Province, North Korea. The county has an area of 420 km, and a population of 110,018. Ŭiju app…Ŭiju is a kun, or county, in North Pyongan Province, North Korea. The county has an area of 420 km, and a population of 110,018. Ŭiju appears as Uiju in South Korea's Revised Romanization and as Yizhou in Chinese sources, as during its occupation by general Mao Wenlong's forces during the Transition from Ming to Qing.