"version" of chunk_split for cyrillic characters in UTF-8

public function UTFChunk($Text,$Len = 10,$End = "\r\n")
{
    if(mb_detect_encoding($Text) == "UTF-8")
    {
        return mb_convert_encoding(
                chunk_split(
                    mb_convert_encoding($Text, "KOI8-R","UTF-8"), $Len,$End
                ),
                "UTF-8", "KOI8-R"
            );
    } else
    {
        return chunk_split($Text,$Len,$End);
    }
}

this is example for russian language