the account is locked

1. 운영체제의 oracle 계정으로 접속
    sqlplus "/ as sysdba"

2. 계정의 lock 정보를 확인 
   select username,
             account_status,
             to_char(lock_date,'yy/mm/dd hh24:mi')   
             lock_date,profile
   from dba_users
   where username = 'SYSTEM';  --> Lock된 유저명

3. account_status 가 LOCKED 이면
   USERNAME     ACCOUNT_STATUS    LOCK_DATE       PROFILE 
---------------------------------------------------------------------
    SYSTEM          LOCKED                    06-05-12          DEFAULT

4. alter user system account unlock;