Background information Edit
This planet was only mentioned in dialogue.
"juh-POOR-ee" was the pronunciation for this planet's name from the script pronunciation guide. 
According to Star Trek: Star Charts (pp. 61-62) and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), in the 2270s, V'ger traveled near or through Japori's system on its course towards Earth.