SQL & PL/SQL

Hello Guru's,
Need your guidance. I am using ASP.NET as front end and trying to execute SQL query which is taking too long to execute because of large amount of data in the base table.
If I use the STOP button from browser it stop the operation but in the Oracle engine the query still runs. Is there any way to identify this query in oracle and kill

Right now I am using DBMS_APPLICATION_INFO package to update module, client and action fields of v$session dynamic view before running the query. I am using above 3 mentioned fields to identify the query and kill the session using sid and serial#. But using this approach my oracle session is getting expired and I am getting message NOT CONNECTED TO ORACLE.

Am I using the right approach....? please put some light on it.

Thanks in advance
GK