Kor kon >> ฅ Kor kuad >> ฃ This two character is not commonly using. It is just a Thai Character, but we less use them, actually there were not use. just a word ฅ.คน dor cha da >> ฎ (ชฎา, >> the crown which Lady Gaga wear in Concert live in BKK) there are many words use this character Dor pa dak >> ฏ (ปฏิบัติ, ปฏิสัมพันธ์, ...) there are many words use this character too

Good question the characters that you ask is the old characters in Thai we rarely used them.

We don't really use Kor Kon and Kor Kuad nowaday. But we still use Dor cha da and Tor pa tak.

Addition กฎ [กด-ghod] and กฏ [กด-ghod] They came from Pali-Sanskrit words. They are same pronunciation but 1.กฎ[dor cha da] means law. You can use กฎหมาย[ghod-mhai] = law , กฎธรรมชาติ[ghod-tham-ma-chad] = law of nature , กฎแห่งกรรม = law of action,reciprocal deeds etc. [dor-cha-da]Some words that we often use like ทฤษฎี[trid-sa-dee] = theory , มงกุฎ[mong-khud] = crown,tiara , ศาลฎีกา[sarn-dee-ga] = supreme court {ศาล[sarn] = court} 2.You can use กฏ[Dor pa dak] when It follow the word ปรา[prar] ex. ปรากฏ[prar-ghod] = appear , ปรากฏการณ์[prar-ghod-gan] = phenomenon and there are many words that use ฏ[Dor pa dak] ex.ปฏิบัติ[pa-Di-bud] = act,practice , ปฏิกิริยา[pa-Di-gi-ri-ya] = reaction etc. [Dor-pa-tak]Some words that we often use like กุฏิ[gu-Di] = cloister , ปาฏิหารย์[pa-Di-harn] = miracle , ปฏิเสธ[pa-Di-sed] = reject , นาฏศิลป์[nard-Da-sin] = dancing art etc. 3.The alphabet ฅ[kor-kon] according to the royal institute,we do not use this alphabet in nowaday but you can see in some places like the name of the TV show - คนค้นฅน 4.The alphabet ฃ[khor-khuad] - the same sound of ข[khor-khai] according to the royal institute,we do not use this alphabet in nowaday. P.S. I searched some information from the internet because many people usually use some words by mistake even Thai people