Attached is how the font "NanumGothic.ttf" (downloadable from here : http://hangeul.naver.com/download.nhn scroll down to the 7 green boxes and it's the third one along the top row) looks:
@ Pixel Size 13
Notice how the letter i appears to be too tall in relation to the other letters.
@ Pixel Size 14
Now the i looks ok:
When hinted with the FT hinter, the letter i remains consistent.
This is with FreeType 2.4.4, with the BCI switched on as is the default.
- Oliver