18세기 왕실 문헌에서 구개음화는 ≪어졔내훈≫에 1%, ≪어졔상훈언해≫에 0.4%, ≪어졔훈서언해≫에 2.7%, ≪어경≫에 8.7%로 ≪윤음≫에 89%로 나타났다. 그리고 ‘ㆍ’의 변화로 인해 거의 나타나지 않는 ‘ㆍ>ㅗ’ 변화를 제외한 ‘ㅡ>ㅜ’ 원순모음화는 ≪어졔내훈≫에 2.5%, ≪어졔상훈언해≫에 5.2%, ≪어졔훈서언해≫에 3.7%, ≪어경≫에 1.6%, ≪윤음≫에 15.5%로 나타났다. 그러므로 18세기의 왕실 문헌에서의 구개음화와 ‘ㅡ>ㅜ’ 원순모음화는 다른 사회적 부류의 문헌과 달리 18세기 중기까지 미미한 상태에서 느리게 확산되다가 18세기 후기에 급속도로 확산되어 S자 곡선과 같은 보편적인 음운변화의 과정을 보인다. 그러므로 왕실 문헌의 구개음화와 ‘ㅡ>ㅜ’ 원순모음화는 역서류 문헌, 자석류 문헌, 불서류 문헌 등에 비해 매우 느리게 확산되는 특성을 보인다. 이와 같이 보수적인 특성을 보여주는 왕실 문헌의 언어 사용 상태는 사회언어학적 접근에서 드러나는 상류층의 언어 사용과 같은바, 그것은 왕실 문헌의 간행에 관여한 사람들이 사대부라는 상류층이었기 때문이라 할 수 있다. 국어의 음운변화에서 드러나는 이러한 특성을 바탕으로, 국어의 역사적 연구는 그 간행에 관여한 사람들의 사회적 특성에 따라 분류한 문헌의 부류별로 이루어질 때 보다 구체적이고 정확한 변화의 과정을 밝힐 수 있을 것이다.

The rates of palatalization in the 18th royal literatures are as follows: 1% in Eoje Naehun, 0.4 % in Eoje Sanghuneonhae, 2.7% in Eoje Hunseoeonhae, 8.7% in Eoje and Kyeongsyemundap, and 89% in Yuneum. Excluding ‘˄>o’ vowel change which is not seen due to the change of the vowel ‘˄' itself, the rates of the ‘ɨ>u’ vowel change (the change of unround vowels into round ones) are as follows: 2.5% in Eoje Naehun, 5.2% in Eoje Sanghuneonhae, 3.7% in Eoje Hunseoeonhae, 1.6% in Eoje and Kyeongsyemundap, and 15.5% in Yuneum. It can be concluded, therefore, that the palatalization and the ‘ɨ>u’ vowel change in the 18th century royal literatures spread slowly until the middle 18th century, but that it spread quite rapidly in the late 18th century, showing the universal pattern of phonological changes of the S-curve. The palatalization and the ‘ɨ>u' vowel change in the 18th century royal literatures, compared with those in translation literatures, Sino-Korean teaching materials, and Korean versions of Buddhist scriptures, show the feature that their diffusion was very slow. This conservative feature of the language use in the royal literatures can also be seen in the language use among the upper classes revealed from socio-linguistic approaches. The reason is that those who took part in the publishing of the royal literatures were members of the upper classes themselves. The characteristics of the phonological changes shows that the historical study of the Korean language can be conducted in a more concrete and precise way, when it takes into account the various kind of literatures written by each social group that followed its own language practices.

The rates of palatalization in the 18th royal literatures are as follows: 1% in Eoje Naehun, 0.4 % in Eoje Sanghuneonhae, 2.7% in Eoje Hunseoeonhae, 8.7% in Eoje and Kyeongsyemundap, and 89% in Yuneum. Excluding ‘˄>o’ vowel change which is not seen due to the change of the vowel ‘˄' itself, the rates of the ‘ɨ>u’ vowel change (the change of unround vowels into round ones) are as follows: 2.5% in Eoje Naehun, 5.2% in Eoje Sanghuneonhae, 3.7% in Eoje Hunseoeonhae, 1.6% in Eoje and Kyeongsyemundap, and 15.5% in Yuneum. It can be concluded, therefore, that the palatalization and the ‘ɨ>u’ vowel change in the 18th century royal literatures spread slowly until the middle 18th century, but that it spread quite rapidly in the late 18th century, showing the universal pattern of phonological changes of the S-curve. The palatalization and the ‘ɨ>u' vowel change in the 18th century royal literatures, compared with those in translation literatures, Sino-Korean teaching materials, and Korean versions of Buddhist scriptures, show the feature that their diffusion was very slow. This conservative feature of the language use in the royal literatures can also be seen in the language use among the upper classes revealed from socio-linguistic approaches. The reason is that those who took part in the publishing of the royal literatures were members of the upper classes themselves. The characteristics of the phonological changes shows that the historical study of the Korean language can be conducted in a more concrete and precise way, when it takes into account the various kind of literatures written by each social group that followed its own language practices.

royal literatures, palatalization, the change of unround vowels into round ones, phonological changes, the S-curve, socio-linguistic approaches