Finally the problem solved.
my OS server was: Linux Oracle
and my client OS was Windows 7
and my browser was IE 9.0
I checked pdf output of concurrent program in other pc with Mozilla Browser.
it hadn't any problem and we can see pdf report on our browser
So I added EBS link to unhandle links by IDM (Internet Download Manager) in order that when I click on View Output button Idm dosn't download pdf anymore automatically
So the pdf file open in my browser and I can see my report and save this on my local hard drive.
anyway I don't know why but the problem solved by this way.