Thank you very much!
It worked great except for one thing.
When I insert "define('PHPDIG_ENCODING','iso-8859-9');" , encoding problem is totally gone, but search can not find most of the results. When I change it to 8859-1 and search with the same keyword, it finds a lot of results.
Could it because I indexed using 8859-1? Would it help if I clear the index and make another one by using 8859-9? Or is that irrelevant?
Again, thank you so much.