After I reinstall my osx, one problem I faced is to install Ruby 1.9.2. I had Xcode 4.2 installed which it comes up with LLVM-based C compiler. This compiler is support for Ruby 1.9.3, but it is not supported by 1.9.2. To solve this, I have to specify the GCC compiler before installing.
$> CC=gcc rvm install 1.9.2