It's a compress type like Winrar.
The tool to open this is
Alzip, most of korean maps are compressed like that.
This website
here have a lot of korean cheated maps (take care when you open this website, because they normally post a nsfw girl pic after the map)
with this kind of protection, but, most of maps compressed by alzip are corrupted to open.
To open alz files, u need to download Alzip and open the alz, then the program will ask for a.00;a.001....
After you open all the files, the program will give you the file inside.