These are the Royal Thai Air Force's "401 Spn. 4 Wing" aircraft grinds.
Copy all textures from the folder "Missing textures" into each individual folder of the RTAF registered numbers.
CoreMods/aircraft/L-39/Liveries/L-39ZA/RTAF 40101 for example
Copy the folder "CoreMods" into the main folder of DCS 1.5 or DCS 2.0
have fun Urbi