Hi Joshita,
You are looking for table CRHD.
The completel answer is:
Pass GEWRK value of MPOS table into the OBJID field of CRHD table, and the description you are looking for, is available in the ARBPL field of the CRHD table.
(The full description of Work Center is available in CRTX table. Input OBJID value to get the 40char description in field KTEXT )
Jogeswara Rao K