Hello,

If you are using UNIX,you can set a cron job to run at every one hour
to check which are the user sessions that are
inactive for more than 1 hour and kill those sessions.

The sql to be executed is given below
*********************************************
spool killsess.sql

select 'alter system kill session '||''''||sid||','||serial#||''''||';' from v$session where username is not null and status='INACTIVE'
and sysdate-logon_time
> .041666667 ;

spool off

@killsess.sql
*********************************************

If you are using UNIX ,You can send mails to the users for
intimating them before killing it.
Shell scripts would make it possible.



Regards
Chithra