They are the Moon-logo and Sun-logo.
Firstly, i have the ideas from the Trong Dong's decoration. There are a lot of simple decorated images on the surface of Trong Dong.
But there too complex and ralate to Vietnamese culture only.
Finally, i've created the sun and moon logo above.
I mention on the motion and the characteristic of moon and sun. The Sun is active and trong, but the moon is passive and quite.