Yoo Hyunju - Flywheelsites News
The pronunciation of greek letters by scientists isn't very different from the pronunciation of the greek letters in the respective countries: American scientists pronounce them pretty much the same way. The oxford english dictionary dates yoo-hoo to 1924, as noted by the american dialect society, and compares it to yo-ho, originally a nautical phrase also sometimes used in yo-heave-ho.
U is oo for nearly all american, and a substantial number of british english speakers in most words when it falls in a stressed syllable after one of the following consonants: /l/ /s/ /z/ u is oo for most.