Ko was the head coach of the Korean team at the second World Taekwondo Championships in 1975, when they swept the gold in all eight divisions, and at the third world championships in 1977, when they captured seven of eight titles. In 1980, he authored the first book devoted solely to World Taekwondo Federation-style sparring.
Ko would eventually take up residence in Germany where he was instrumental in spreading Olympic-style taekwondo in Europe. In 2005 he was named chairman of the World Taekwondo Federation's technical committee. He was honored as "Grandmaster of the Year" by Taekwondo Times in 2008. It's been reported he died of heart failure after suffering from pneumonia.