Run the following query to find out who are the Oracle Apps Users currently Logged into the application.
SELECT DISTINCT icx.session_id, icx.user_id, fu.user_name, fu.description FROM icx_sessions icx, fnd_user fu WHERE disabled_flag != 'Y' AND icx.pseudo_flag = 'N' AND (last_connect + DECODE (fnd_profile.VALUE ('ICX_SESSION_TIMEOUT'), NULL, limit_time, 0 , limit_time, fnd_profile.VALUE ('ICX_SESSION_TIMEOUT')/60) / 24) > SYSDATE AND icx.counter < limit_connects AND icx.user_id = fu.user_id;