(LEAD) (Olympics) Mischievous archer turns serious to capture historic gold
(ATTN: FIXES detail in para 3; ADDS photo)
By Yoo Jee-ho
RIO DE JANEIRO, Aug. 12 (Yonhap) -- When Ku Bon-chan first picked up archery in fifth grade, even his parents didn't think the teenager would last a week because he could never stay still and c