Windows PHP scandir() 中文 亂碼

$filelist = @scandir($UPLOAD_PATH);

// remove dir '.' , '..'
unset($filelist[0]);
unset($filelist[1]);

if($filelist)
{  
    if(PHP_OS == "WINNT")
    {  
        foreach($filelist as $key => $value)
        {  
            $filelist[$key] = mb_convert_encoding($value, "UTF-8", "big5");
        }  
    }  
}