Name first derived as a slang-term definition in the 21st century (2011). Commonly used as a noun and an adjective, to describe a person. The most well known meaning of this name is "someone who is giddy and happy 99.2736% of the time", "may seem 'blunt' and 'dull' in the outside, but the true nature of the person is quite the opposite", "seems to have perfected social skills in many different forms" and last but not least, "someone who is also a great techie (formally and mainly for a girl.)"
Man, that girl is such a HyeIn! How does she do it?!
That is something HyeIn would do!