By YURI KAGEYAMA Toyota admitted design problems with the brakes in its prized Prius, adding to the catalog of woes for the world's No. 1 automaker still reeling from a massive U.S. recall involving faulty gas pedals.Toyota Motor Corp. spokeswoman Ririko Takeuchi said Thursday that Toyota discovered there were design problems with the antilock brake system and corrected them for Prius models sold since late January, including those being shipped overseas.But the company said it was still investigating how to inform people who had bought the gas-electric hybrid cars.