The purpose of this study was to clarify origin-based layer in Sino-Korean by comparing 16 groups in Middle Chinese with Sino-Japanese Kan’on. and Sino-Japanese Go’on focusing on rhyme system in Sino-Korean. Accordingly, this study aimed to specifically clarify which period in Middle Chinese the rhyme system in Sino-Korean has the origin by analyzing consonantal form, which is recorded in totally 24 kinds of data for Sino-Japanese and Sino-Korean such as 12 kinds of data for Sino-Korean, which included Korea-Chinese character in the Sino-Korean from 15th century to the 16th century, 6 kinds of data for Sino-Japanese Kan’on, and 6 kinds of data for Sino-Japanese Go’on. Next, the aim was to clarify side by side whether the form of having been differently reflected Sino-Korean, which was reflected in Korea-Chinese character from the 15th century to 16th century, from the original pronunciation in Chinese language pronunciation, is what reflected historical difference in the original pronunciation, or is the form that experienced its change as native language in light of phonological system in the accepting process.

As this research methodology, this study reconstructed ancient Chinese by making it segmentation into early middle Chinese in the 5th century, middle Chinese in the 7th century, and late middle Chinese in the 8th century as for ancient Chinese that has been classified simply into one period so far in order to discuss the origin of Sino-Korean. Accordingly, how a phonological change in these three periods was reflected in Sino-Korean became a decisive clue in closely examining the origin of Sino-Korean.
Scholars'' many theories have been divergent so far on the origin layer in Sino-Korean. However, this study aimed to clarify which period in middle Chinese the rhyme system in Sino-Korean has the origin and also to introduce new discussion different from the research until now by analyzing consonantal form, which is written in data of Sino-Japanese and Sino-Korean. For example, as the phenomenon of i-vowel epenthesis in the main subject is the general phonological phenomenon within Korean language that took place from the 15th century earlier, it demonstrated that this phenomenon of i-vowel epenthesis led to the occurrence in a case that i-vowel is proclitic in Sino-Korean as for consonantal form of being not proclitic i-vowel in Sino-Japanese and Sino-Vietnamese due to this phenomenon of i-vowel epenthesis. As mentioned in the above, it proved to be mixed a form of having experienced a change in native language in light of Phonological system in the process of accepting the original pronunciation in Chinese language, not the difference in the origin layer in Sino-Korean.
Arranging the above results, they are as follows.

1. The rhyme system in Sino-Korean is judged to be what the early middle Chinese(layer A) and middle Chinese(layer B) became central axis. The detailed description by rhyme was demonstrated in the main subject. Summarizing characteristics of early middle Chinese and middle Chinese by being divided from 1st rhyme to 4th rhyme, they are as follows.

Firstly, there is rhyme of distinguishing 1st double rhyme in Sino-Korean. In the late middle Chinese, the 1st double rhymes meet each other. The 1st double rhyme is in antagonistic relationship between ?, which is mid-back vowel, and ?, which is low-back vowel. In other words, ① Hai-rhyme(?韻, -?i) & Tai-rhyme(泰韻, -?i) ② Tong-rhyme(東韻, -?uŋ/k) & Tong-rhyme(冬韻, -?uŋ/k), ③ Dam-rhyme(覃韻, -?m/p) & Dam-rhyme(談韻, -?m/p) are opposed, respectively.
In Sino-Korean, it is discriminating ① Hai-rhyme(?韻) as -?i form and Tai-rhyme(泰韻) as -ai form in Hai?Tai-rhyme(??泰韻). It is confusing ② Tong?Tong-rhyme(東?冬韻) as -oŋ/-ok form. It is confusing ③ Dam?Dam-rhyme(覃?談韻) as -am/-ap form, -?m/-?p form, and -am/-ap form.

Secondly, there is rhyme of distinguishing 2nd double rhyme. In the late middle Chinese, the 2nd double rhymes meet each other.
The 2nd double rhyme is in antagonistic relationship between ?, which is mid-front vowel, and ?, which is low-front vowel. In other words, ① Jie-rhyme(皆韻, -?i) & Guai-rhyme(?, -ai)?Jia-rhyme(佳韻, -ai) ② Geng-rhyme(耕韻, -?iŋ/k) & Geng-rhyme(庚韻, -aiŋ/k) ③ Shan-rhyme(山韻, -?n/t) & Shan-rhyme(刪韻, -an/t) ④ Xian-rhyme(咸韻, -?m/p) & Xian-rhyme(銜韻, -am/p) are being opposed mutually.
In Sino-Korean, it is discriminating ① Jie-rhyme(皆韻) as -?i form and Jie?Jia-rhyme(??佳韻) as -ai form?-a form. It is confusing ② Geng?Geng-rhyme(耕?庚韻) as -?iŋ/-?ik form, ③ Shan?Shan-rhyme(山?刪韻) as -an/-al form. ④ Xian?Xian-rhyme(咸?銜韻) as -am/-ap form.

Thirdly, it is differentiating between 3rd-grade Eul(medial-i) and 3rd-grade Gap(medial-i).

In the late middle Chinese, the joint between 3rd-grade Eul and 3rd-grade Gap is mostly reflected. However, Sino-Korean is generally distinguishing two rhymes.

Fourthly, in the late middle Chinese, the 3rd-grade Gap and the 4th-grade exclusive rhyme meet. The joint between the 3rd-grade Gap and the 4th-grade exclusive rhyme can be considered to be general tendency of early middle Chinese.
Sino-Korean reflects the joint between the 3rd-grade Gap and the 4th-grade exclusive rhyme, However, it was already happening from the Northern and Southern Dynasty. This can be considered to be general tendency in the early middle Chinese of showing what the 4th-grade exclusive rhyme is being changed into Yo’on(拗音) from Chyoku’on(直音). Even Sino-Korean is confusing completely. What the joining phenomenon in each rhyme, on which Kono Rokuro(河野六郞:1968) addressed as characteristic of the late middle Chinese, was discriminating even middle Chinese, wasn''t varied suddenly with reaching the late middle Chinese, but has possibly of having understood each other already from the Northern and Southern Dynasty.

2. The rhyme system in Sino-Korean is judged that the influence of the late middle Chinese had been partially formed only in rhyme system unlike the assertion by Kono Rokuro(河野六郞:1968). The detailed description by rhyme was demonstrated in the main subject.

3. The rhyme system in Sino-Korean is judged that the influence following the early modern Chinese had been partially formed only in rhyme system unlike the assertion by Arisaka Hideyo(有坂秀世:1936). The detailed description by rhyme was demonstrated in the main subject.

4. Sino-Korean is difficult to be considered to have reflected historical difference in the original pronunciation, is judged to be a form of having experienced a change as a native language in light of the phonological system in the process of accepting the original pronunciation in Chinese language, and is a layer of being difficult for discrimination in the origin layer. The detailed description by rhyme was demonstrated in the main subject.

As examined in the above, the origin layer of Sino-Korean in this study was standardized again by middle Chinese after being established consonantal system to some extent by early middle Chinese, resulting in having been demonstrated that early middle Chinese and middle Chinese became the central axis of rhyme system in Sino-Korean. Accordingly, the influence following the late middle Chinese and the early modern Chinese is judged to have been formed partially only in rhyme system.
However, Sino-Korean is mixed many layers following early middle Chinese, middle Chinese, late middle Chinese, and early modern Chinese over each rhyme, thereby having a very complicated double-layer property. Also, Sino-Korean is difficult to be considered to have reflected historical difference in the original pronunciation, and is being mixed layers of being difficult to discriminate the origin layer as a form of having experienced a change as a native language in light of the phonological system in the process of accepting the original pronunciation in Chinese language.