Dear John,
Thank you for your quick reply.
I often update the mesh geometry, because my research subject is about 4D dose calculation with animated phantoms.
I have tested my code by replacing the G4Mesh and G4VSceneHandler codes with the files you have attached, and it worked perfectly, although, as you already mentioned, it was a bit slower than before.
Phantom box also well appeared!
Thank you very much for your help!!
Best wishes,
Haegin