Currently I have one common database which to be used by different applications. I decided to give each one a schema. For each schema there are different user accounts to be created. For this reason, I would like to know how to create a user account which uses the same schema as another user account. It is like to have a master account and some dependent accounts associated with.
As far as I can tell, no way. A schema = a single user + its objects. In order to make two (or more) users use the same schema objects, you'll have to create those users and grant required privileges on all (or some) objects to those users, such as
GRANT SELECT ON original_user.table1 TO another_user;
GRANT EXECUTE ON original_user.procedure TO another_user;