A modified version of South Korean dubeolsik (two-set type) for old hangul letters. This layout is created by Microsoft and the ActiveX plugin is being used in the official website of the National Institute of the Korean Language.
Note:

The shapes and arrangement of keys are based on the typical IBM PC-compatible/Windows keyboards sold in South Korea (see File:KB South Korea.svg).
The backslash is replaced with the Won sign or both of them are printed on many South Korean keyboards. The (halfwidth) backslash is replaced with the Won sign in many South Korean encoding systems.
Exception: On the Korean keyboards for Mac because the backslash is printed because it is not replaced with the Won sign in Mac OS.
The vertical bar | (Shift+\) is also replaced as the broken bar ¦  on some South Korean keyboards, but the broken bar in Unicode (U+00A6) is not inputted by most of Korean IMEs. The (halfwidth) vertical bar and the broke bar are ambiguous in some character encoding systems such as ASCII and EUC-KR.
In this picture, the F in a quadrangle (Shift+ㅓ, or Shift+J on QWERTY) means "to finalize [or terminate] the hangul combination". The old Korean spellings contains more complicated consonantal groups (such as ㅺ, ㅴ) than in the modern one, so it is useful because Dubeolsik can cause ambiguity between the first and final consonants. This is same as in the E in a quadrangle in the Dubeolsik for Old Hangul in Nalgaeset (NG3).
Own work
Yes0song