Kim assumed power after his father Kim Jong Il died of an apparent heart attack in December 2011.
The North Korean government recently revised state rhetoric in an effort to strengthen the position of the leader, who was said to be in his late 20s when he assumed power.
Research conducted by the Institute for Peace and Unification Studies at Seoul National University found the young leader had a general sense of image appeal because of his age and appearance in state media, the Yonhap News Agency in South Korea reported Thursday.
The university report said Kim has been on the television screens of North Korean viewers more than his father was on TV.
Kim Jong Un is the supreme leader of North Korea, heading the military and ruling Workers' Party of Korea.