foreach my $file (@files) {
  my  $OUTFILE_fname = $file.".html";     # output file name

    open ( OUTFILE, '>', result_dir/$OUTFILE_fname )
        or croak "$0 : failed this file $OUTFILE_fname : $!\n";

    my $result  = process($file);

    print OUTFILE $result;

    close ( OUTFILE );         # close output file
}