Commander Brad Yacobian was a Starfleet officer in the 22nd century.
Yacobian was in charge of vehicle development during the production of the NX-01. (Star Trek: Enterprise set artwork)
In January 2155, Yacobian was working in Mission Operations at the Fleet Operations Center on Earth. His office was in room #1056. (ENT: "Demons" set artwork)
In 2161, Yacobian, wearing an Enterprise assignment patch, attended the Federation Founding Ceremony and witnessed the speech of Captain Jonathan Archer. (ENT: "These Are the Voyages...")
Background information
The character was portrayed by producer Garfield Reeves-Stevens and named after producer and unit production manager Brad Yacobian.
The name "B. Yacobian" appeared on two pieces of set artwork during Star Trek: Enterprise:
The name "Brad Yacobian" appeared on the nametag of producer Garfield Reeves-Stevens during his cameo in "These Are the Voyages...". Although not visible during the episode or in background material, this was revealed by Larry Nemecek in Issue #124 of Star Trek Magazine.
Reeves-Stevens was also referred to jokingly as "Commander Gar Reeves-Stevens" in the Enterprise Secrets special feature on the DVD for Enterprise season 4.