Advanced Engineering & Planning Corp. Inc. (AEPCO), an engineering and research firm providing quality technology for government and private sector clients, relocated its headquarters from 15800 Crabbs Branch Way in Rockville to 555 Quince Orchard Road in Gaithersburg. The tenant moved due to the firm's expansion of operations and has committed to a 10-year lease agreement of 20,699 square feet on the fourth floor.