I quote because it s pretty accurate: - when it's at the beginning of the word, it's pronounced 의 {ui} - if it's used at the end of the word as a possessive marker, it's usually pronounced as 에 {ae}. However, some Koreans pronounce it 의 {ui} in this case too - If it's the end syllable of a word, it's normally pronounced 이 {long e} As an example, 민주주의의 의의 (democracy's meaning/significance) is pronounced {민주주이에 의이}. The {wi} pronunciation seems to be the most difficult for westerners to pick up. I have found that it is closest to the the French u, but with a more drawn out "ee" at the end. Contrary to the Romanized spelling, there is no 'w' sound. http://bonewso.net/koreangrammar/tiki-read_article.php?articleId=312

에 is a wrong pronunciation. Just, Koreans say 에 instead of 의 because 에 is easier to pronounce than 의 but you should know that is a wrong sound. Finally, 희 differs from 의. 희 is nearer to hee than ee.

의 = ui