After banging my head for quite a long time I found the solution.
I changed the locale
of my system to korean and it worked.
The locale of system(windows 7) can be changed in the following mentioned way.
Control Panel --> Clock, Language, and Region --> Region and Language -->
Administrative --> Change system locale
What it did in actual was "it changed the system codepage
to 946(for korean)". The default code page of system(windows) for English is 437.
The command which can be used to know the current code page of system is chcp
(CHANGE CODE PAGE). If you use this command then it will give you a result like Active code page: 437
. Below link provides more detail about code page.
http://www.uwe-sieber.de/codepage_e.html
For knowing more about robocopy visit the following links.