HONG KONG — Imagi Animation Studios, the Hong Kong outfit that recently produced “Teenage Mutant Ninja Turtles,” has appointed another DreamWorks Animation alumnus.Tim Cheung joins as animation VP to manage the 400-plus animators in Hong Kong. In March, the company hired DWA’s Cecil Kramer, Maryann Garger and Mark Tarbox. Cheung, who was with DWA for 12 years as a CGI animator, worked on “Antz” as senior animator and the “Shrek” trilogy as directing animator, supervising animator and head of character animation, respectively. His first assignment at Imagi will be upcoming pics “Gatchaman” and “Astro Boy,” both skedded for release in 2009. Cheung will report to co-CEO Douglas E. Glen and Francis Kao, deputy chairman, co-CEO and chief operating officer.