Complex sentence: On June 8,1997, he became the first Korean to sail around the world alone, by completing a circumnavigation on his 30-foot sailboat "선구자 2 (Pioneer 2)", voyaging for over 70,000 kilometers in 3 years and 5 months.
Split into simpler sentences: On June 8,1997, he became the first Korean to sail around the world single-handedly. He completed the circumnavigation on a 30-foot sailboat "선구자 2 (Pioneer 2)", voyaging for over 70,000 kilometers in 3 years and 5 months.