College

As one of the region's biggest prospects, Choo was widely expected to attend Yonsei University or Korea University and raised eyebrows by choosing Hanyang University instead. In a 2012 interview, he stated that the decision was due to his desire to play more regularly and that neither Yonsei nor Korea University could guarantee him playing time as a freshman.^[3] In the 1997 National Basketball Festival, he went on to become the competition's top scorer, beating the likes of Seo Jang-hoon (Yonsei) and Hyun Joo-yup (Korea).^[3][4] At that time, the duopoly of Yonsei University and Korea University was dominating college competitions and, partly due to Hanyang's poor results, Choo was often overshadowed by the likes of Seo, Hyun, Woo Ji-won, Shin Ki-sung and Chun Hee-chul.^[4]

Professional

Choo's career coincided with the founding of the professional Korean Basketball League in 1997.^[4] He was signed by Daejeon Hyundai Dynat, which was later taken over by affiliate KCC Corporation and is now Jeonju KCC Egis. During Hyundai's early years, Choo was best known as part of the "Lee-Cho-Choo" trio alongside point guard Lee Sang-min and swingman forward Cho Sung-won which spearheaded the team's domination of the league during its early years.^[5] Choo, being the tallest of the threesome, was often tasked with defensive duties and also provided an added option around the paint due to his accurate shooting.^[6]

Although Choo was largely overshadowed by his more flamboyant teammates, he gained a reputation for his cool and calm demeanor during high-pressure and clutch situations, which is reflected in the fact that he was the league's free throw percentage leader for a record six seasons. He made the "180 Club", having achieved a 52.4% field goal percentage, 41.3% three-point field goal percentage and 90% free throw percentage during the 2004–05 season.^[7] His unflashy yet consistent playing style and clean private life earned him the sobriquet "Silent Strong Man" (소리없이 강한 남자), a contrast to colorful nicknames assigned to his contemporaries such as "Rambo Shooter" (Moon Kyung-eun), "Bullet Man" (Shin Ki-sung), "Airborne" (Chun Hee-chul) and "Magic Hippo" (Hyun Joo-yup). He was highly-regarded even by fans of opposing teams; when he scored against Seoul SK Knights in February 2012 to reach 10,000 career points, Knights fans gave him a standing ovation as a mark of respect.^[8][9]

Choo announced his retirement at the end of the 2011–12 season.^[10] His number 4 jersey was retired by the club.^[11] During his final season as a player, he became the second player in KBL history to reach the career benchmark of 10,000 points and made the playoffs for a record 13th time.^[12]

National team

Choo participated in the 1998 FIBA World Cup and the 1998 and 2002 Asian Games.