He said in the five years since Kim Jong-un took power in December 2011, about 140 officials have reportedly been purged, while as many as 2,000 officials were ousted in the three years following Kim Jong-il assuming complete control of the country in October 1997.

After taking control of the country, the late leader led massive background investigations into officials, from which many were charged with treason, including Mun Song-sul, a secretary in the ruling party's central committee.

Cheong cited this event as one of the key factors in the higher number of purges under the previous leader.

The researcher also said that a reign of terror alone could not fully account for the characteristics of the current Kim Jong-un regime because his ruling style is now displaying many different aspects.

The leader is friendly to the public as his grandfather and North Korean founder Kim Il-sung was, but on the other hand, he terrorizes officials and orders unconditional obedience from all North Koreans, Cheong stressed.

"Following the death of Ki Jong-il, many experts in South Korea and abroad predicted the Kim Jong-un regime would not last long, but Kim has succeeded in solidifying his position as the highest leader in and outside of the country," according to Cheong. (Yonhap)