He was a professor before his expedition to Exo III. He taught that "freedom of movement and choice produced the Human spirit". He became romantically involved with one of his students, Christine Chapel, who became his fiancée.
In or shortly before 2261, Korby led an expedition to Exo III, where he was badly injured by exposure to the planet's bitter cold. He lived long enough to discover an ancient android civilization there. Using their techniques, he constructed an android body into which he transferred his consciousness. His ruined corporeal form expired that year, but his consciousness survived for over five years as an android. (TOS: "What Are Little Girls Made Of?")
Background information Edit
Roger Korby was played by actor Michael Strong.
When Korby's image was introduced in the script of "What Are Little Girls Made Of?", he was referred to as "an intelligent-looking, but strong-faced man in his late-forties, with a self-assured and commanding presence himself." The cast list called him "Robert Korby", while the rest of the script called him Roger. 
On his archival picture, Korby was wearing a turtleneck shirt left over from the two pilots.
The Star Trek: New Visions "The Survival Equation" comic reveals that Andrea's features were patterned after a member of Korby's crew, Andrea Milton, who had died prior to the events of "What Are Little Girls Made Of?".