How to map
You can follow the basic instructions in the main wiki, but in Korea there is usually a lot of information about the tunnel on a plaque on the tunnel itself which we can record. On a motorway it is not possible to read this information, but there are larger signs displaying the name=* and (usually) the length=*.
The tunnel name
Roadsigns near the tunnel indicate the name of the tunnel in Hangul (Korean) and English. The sign will show the distance to the tunnel in metres, and usually the length of the tunnel in metres. We need the Hangul for the tags. In this example the name of the tunnel is 함안2터널. There may also be an English name to copy, but if not 터널 is Korean for tunnel, so in English this is Haman 2 Tunnel. This sign is 500m from the tunnel.
For this example tunnel the tags are:
name=함안2터널 name:en=Haman 2 Tunnel name:ko=함안2터널 name:ko-Latn=Hamaniteoneol
The tunnel name is often marked above the tunnel mouth as well.
The tunnel length
On the sign above we can see 터널길이, which is Korean for tunnel length. This tunnel is 500m long.
The information from this photo can be tagged as follows:
Sometimes the tunnel length can be found on a smaller sign, as shown below. The large blue sign shows the tunnel name and length (2551m). A smaller, triangular sign shows the length again, but no other information.
name=창원1터널 name:en=Changwon 1 Tunnel name:ko=창원1터널 name:ko-Latn=Changwonilteoneol length=2551
Note that there is only one name=* tag, so if the tunnel has a name and is on a named road the name of the tunnel takes precedence. This is being addressed by the following proposal: Using relations