Oracle Database Discussions

I want to perform the date conversion of a column.

My requirement is:

I have a column named 'SYS_DT_TM' with datatype as DATE. The Date values in this column resides in GMT format. Now, I want to select this column values and display them in the date that is current. Now it is DST period. So, it has to display in DST timings. When DST completes, it has to display in EST timings.(That is, it has to take care of both Eastern timings-EST and Daylight savings time-DST.)

New_time(created,'GMT','EST') converts to EST timngs.
similarly, New_time(created, "GMT','EDT') converts to DST timings.

But, I want to know if there is a function to perform both the above functionalities according to the current time periods.
can someone please help?