Kim Chŏng-ŭn, AKA Gim Jeong-eun, AKA 김정은, usually AKA in English Kim Jong-un, i.e. the Supreme Leader of North Korea
I am considered a great in my field.
Especially in North Korea, you are a great politician, an undisputed natural leader that is second only to your grandfather.
If you remove the first three letters of my surname,
If you remove three letters from 김 (Kim), you get an empty string (note that 김 is three letters both in the original (jamo) and the transliteration(s))
the remaining letters are twice of what you get when you remove the first three letters of my forename.
The remaining letters form an empty set, which is twice of an empty set that you get when you remove three letters from Kim (because in Korean, surname comes first and is therefore a forename as well). You can also argue that removing three letters from 정 (Chŏng, which is three letters long in the original) gives you also an empty set (neglecting the 은), if you disagree with this definition of a forename.
What's more, the letters that remained in my forename also appear together in the name of my birth country.
trivially, an empty set is a subset of any set