The heads of South Korea's 10 biggest business groups had to serve in various posts for 20 years at the family-controlled groups before taking the helm at the age of 49 on average, a survey showed Thursday.

Hanwha Group Chairman Kim Seung-youn was the youngest to ascend to the throne at the age of 29 in 1981, after the sudden death of his father Kim Jong-hee, the founder of the group leading the country's explosives industry, according to market researcher Chaebul.com.

Kim Seung-youn ascended to power just one year after he was appointed Hanwha vice chairman upon returning home from studying in the United States in 1980.

Chung Mong-joon was the second youngest as he became the chairman of Hyundai Heavy Industries Co., the country's top shipbuilder, at 36 in 1987.

Chung served only four years until 1991 and then entered politics.

SK Group Chairman Chey Tae-won took over at 44.

Lee Kun-hee became Samsung Group chairman at 45 in 1987 when Lee Byung-chul, his father and Samsung founder, died. Lee Kun-hee had served in various positions at Samsung affiliates for 21 years.

Among those who took over in their 50s are LG Group Chairman Koo Bon-moo, Lotte Group Chairman Shin Dong-bin, GS Group Chairman Huh Chang-soo, Hanjin Group Chairman Cho Yang-ho and Doosan Group Chairman Park Jeong-won.

Chung Mong-koo took over Hyundai Motor Group at 62 in 2000.

Hyundai Motor Group was the fifth biggest business group in South Korea with 36 trillion won ($31.5 billion) in assets at the time. It grew to the second largest with 210 trillion won in assets as of the end of last year. (Yonhap)