The news media tell us that the recently deceased Dear Leader of North Korea, Kim Jong-il, will be succeeded by his third son, Kim Jong-un. On radio and TV I have heard this name pronounced either as kɪm dʒɒŋ ʊn or as kɪm dʒɒŋ ʌn. Which is better?
In hangul it is spelt 김정은. In the Revised Romanization system, now official in South Korea, this transliterates as Gim Jeong-eun, or in the McCune-Reischauer system as Kim Chŏng-ŭn.
So the romanization “Kim Jong-Un” accords with neither system.
Given the Korean spelling 김정은, we expect the pronunciation ɡ̊im d̥ʑ̥̯̯ʌŋ ɯn. The vowels in the last two syllables are back and unrounded. The first, spelt ㅓ and conventionally shown in IPA as ʌ, tends to sound to British ears more like ɒ, despite being unrounded. So pronouncing J(e)ong in English (BrE) as dʒɒŋ (rather than dʒʌŋ) seems a good idea.
The vowel in the last syllable is more problematic. Spelt ㅡ, and represented in IPA as ɯ, this is a vowel quality (close back unrounded) that appears exotic to us and for which we have no equivalent. Pronouncing it as English ʌ is wrong, since that is the sound we use for ㅓ. Using English uː would be inaccurate, since that is the sound we use for Korean ㅜ (as in the last syllable of 반기문 Ban Ki-moon). So I would vote for ʊ as the nearest English equivalent, giving kɪm dʒɒŋ ʊn as the best way of anglicizing this name, at least for BrE.
Here's the Guardian's cartoon.