Anchor: Thursday, which is the fourth anniversary of Kim Jong-il's death, also marks four years since Kim Jong-un succeeded his father as the North's leader. During that time, 73 percent of the top brass of the North's ruling Workers' Party, government and military have been replaced.
Our Kim Eun-ji has more on changes to the North's power structure.
 
Report: Thursday marks the four-year anniversary of former North Korean leader Kim Jong-il's death.
 
Terror still reigns in the North, four years after the young leader Kim Jong-un assumed power. 
 
Only two of Kim Jong-il's seven closest aides, who escorted the funeral car in 2011, remain in power. The other five, including Kim Jong-un's uncle Jang Song-thaek, have been executed or purged.
 
This year, former defense chief Hyon Yong-chol was executed and a top military official Choe Ryong-hae was banished to a collective farm.
 
New faces such as Hwang Pyong-so, director of the North Korean military's General Political Bureau, and deputy director of the ruling Workers’ Party of Korea, Jo Yong-won, have taken their places. 
 
Among 109 key positions in the Workers' Party, government and military, 79 officials have been replaced in the last four years.
 
The defense minister has been replaced six times while the chief of the general staff of the Korean People's Army has been replaced four times.
 
Professor Nam Joo-hong, a North Korea expert at Kyonggi University's Graduate School of Politics and Policy, said current leader Kim Jong-un carried out a reign of terror to establish military discipline in a short time.
 
He expects that the generational shift in the power base will be completed at the Workers' Party congress in May.
Kim Eun-ji, KBS World Radio News.