Now I have the ISO file but I don't want to burn it into DVD so I wonder if there is a way to install Windows 8 right from hard disk ? (do a clean installation from DOS not from any Windows system)
There are two main solutions to install Windows 8 without any optical media (typically using a 4Gb+ USB flash drive).
1. The "Upgrade Assistant" official (promoted) one
If you are already using a previous version of Windows, you can launch the Windows 8 Upgrade Assistant which, among other things, "provides the option to buy, download, and install Windows 8". You can download the ISO file or create a bootable flash drive from this wizard. If you need the ISO file or if you prefer to use this official solution, I recommend the excellent How To Clean Install Windows 8 Pro Upgrade step-by-step tutorial.
By the way, since I bought Windows 8 online, I didn't receive any DVD or even any link to download an ISO, so this first solution is the only one I came up with to download the file and proceed to the installation...
2. The "Windows 7 USB/DVD download tool" official-but-not-really-promoted one
This solution requires you to own the ISO file already (cf. solution #1). Actually The Windows 7 USB/DVD download tool won't download anything, but it will help you to get your flash drive ready for the installation.
This free program from Microsoft properly formats your flash drive and then copies the contents of the Windows 8 installation ISO file you have to that flash drive.
Once again, there are some nice and clear step-by-step tutorials over the Web, like How To Install Windows 8 From a USB Device.
Also you might want to know about an interesting third alternative found on Superuser that will spare you a DVD and a flash drive:
3. Install from a partition
Start by creating a 8GB NTFS partition on your hard drive. Then
Extract your ISO file to the 8Gb partition's root folder.
Use Disk Manager to mark that partiton as active.
Open cmd and type the following command, not include the double quote, asuming E is your 8GB partition
bootsect /nt60 E: /force /mbr
Now you can boot into your windows 8 installation. To boot it back to your windows you can use the repair tool inside the windows installation.
Bootable USB memory stick (plenty of detailed instructions online as to how to create it) is the only non-DVD local option. I don't believe it's possible to install it from an ISO just on a partition on the local hard drive.
It is possible to install from a Network Share but this of course involves a second machine and is more complicated.