U+AC8A Hangul Syllable Geop

The Wikipedia has the following information about this codepoint:

Hangul Syllables is a Unicode block containing precomposed Hangul syllable blocks for modern Korean. The syllables can be directly mapped by algorithm to sequences of two or three characters in the Hangul Jamo Unicode block:

• one of U+1100–U+1112: the 19 modern Hangul leading consonant jamos;
• one of U+1161–U+1175: the 21 modern Hangul vowel jamos;
• none, or one of U+11A8–U+11C2: the 27 modern Hangul trailing consonant jamos.

This block is encoded according to the canonically equivalent order of these (two or three) jamos (one in each subrange of jamos above) composing each syllable.

Note that a full Hangul syllable may include one of these characters but may be preceded by one or more leading consonant jamos, and followed by one or more trailing jamos (possibly preceded by one or more vowel jamos if the encoded syllable is composed by two jamos does not include any trailing consonant jamos). As well some Hangul syllables may not include any one of these precomposed character. But such extension of the Hangul script (which allows creating more complex syllables composed in the same square) is not very common in modern Korean.