Hi Jihwan,
what are you up to?
Do you have a sensor? Have you downloaded and extracted the SDK?
There is a folder inside the SDK called 'install'.
enter that folder and do the following.
1. sudo chmod +x install.sh
2. sudo ./install.sh
this should install the driver for Orbbec Astra camera.
to test you need to compile the samples provided. otherwise you may use the pre-compiled ones.
Hope this helps.
Cheers,
Prasanna