If I deffered exam, which year will effect???
I mean if I take summer school, the mark effects on next year GPA.
so... If I deffered 2nd semester exam, where my mark count on?? this year or next year??

Your best bet would be to ask the registrar's office, however I do believe that the mark would still count towards the GPA of the year in which you took it once you've written the exam.