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Study The Chungju Goguryeo Monument with Advanced Technology

Chungju Goguryeo Monument(National Treasure No. 205) was discovered in 1979 at the entrance of Yongjeon-ri, Gagum-myeon, Jungwon-gun, Chungcheongbuk-do. This Chungju Goguryeo Monument is the only Goguryeo monument found on the Korean Peninsula. This describes King of Goryeo as '高麗大王', and expresses King of Silla as ‘東夷寐錦’(Dongyi Mageum) and the relationship between Goguryeo and Silla as ‘如兄如弟’(be close and intimate like a brother). This is a valuable relic that can look at the relationship between Goguryeo and Silla as well as the history of Goguryeo since the 4th century.

Monument has been worn heavily for 1,600 years, and there is a limit when grasping the form of the correct letter with rubbed copy or eye. This was controversial in the reading of letters from the time of discovery. In 2000, scholars gathered to hold a reading session, but the reading is still not complete. In 2019, on the 40th anniversary of the discovery of Monument, NAHF began research on Chungju Goguryeo Monument by applying advanced science and technology based on epigraphy. As a result of the study, NAHF published the resource book about 『忠州高句麗碑(Chungju Goguryeo Monument)』.

The Main Contents of the Resource Book about 『忠州高句麗碑』

The resource book contains ultra-high-resolution photographs, such as watching Chungju Goguryeo Monument directly from the local area. Print possibles with the same size as Monument. And the details of the surface are reproduced close to reality, so that artificial strokes and natural cracks can be distinguished. So it is useful for reading inscriptions.

NAHF participated in the '2019 survey project on the Kumseokmun through rubbed copy' commissioned by the Cultural Heritage Administration to the Buddhist Central Museum. So we were able to use the latest version of the rubbed copy. The rubbed copy made two pairs. We tapped the surface with ink sticks, attached paper on it, and shot the lights to take pictures. The letters were then relatively clear. The Adobe Photoshop program was operated to treat the photo file with rubbed copy as 'black and white' and 'reversal' to pursue the best effect. And we presented a single-layer/multi-layered rubbed copy together.

In this study, RTI(Reflectance Transformation Imaging) technology was first applied. It uses lighting to shoot from various angles and read letters according to the direction of light. The front and rear of Monument were divided into three areas: upper, middle, and lower, and the left and right sides were divided into two areas: upper and lower. Chungju Goguryeo Monument is not easy to distinguish between each letter and the bumps of the stone; and the shape of the letter is better recognized when color is visible. So, the resource book contains images using Diffuse Gain in rendering mode.

In addition, three-dimensional modeling work on Monument was carried out using various scanners. The digital model of Monument has relatively well represented the overall shape and inscription, and the quality of polygon mesh and RGB texture mapping was also excellent. This was used for precise measurement of Monument, digital reading of inscriptions, and production of 3D printing replicas. In particular, each letter was rendered in various ways, and the traces of the letters and the depth of the stroke were found in the parts that could not be distinguished by the eyes of the human. The 500 letters confirmed by NAHF and the Society for Korean Ancient History were made into photographs, RTI, rubbing, and 3D images and published in the resource book. So, not only experts but also the general public can see the form of letters.

In addition, the transcripts and readings of the reading session, photographs and rubbing at the time of the discovery in 1979, and the rubbing produced by the Goguryeo Research Society in 2000 were included. It is a comprehensive resource book for Chungju Goguryeo Monument.

The Results and Meaning of the Study

One of the achievements of this study is that a new reading has been presented for the controversial part. We have read eight letters, '永樂七年歲在丁酉', written on the top of the Monument, which has been discussed about the specific form and existence of letters. In addition, the existing '十二月廿三(五)日甲寅' was modified to '十二月廿七日庚寅' in the 7th row of the front. And there are the letters '辛酉年' of the 3th row on the left side, which was the main clue to the Monument's age. We read the letters in '功二百六十' this time.

Result of reading Chungju Goguryeo Monument

Through this, it seems to be able to provide clues to solve some controversial problems. First, it will be able to end the controversy about the beginning of the inscription. The year '永樂七年歲在丁酉' is identified at the top of the front, and it leads to '五月中' in the text. Therefore, the front can be seen as the first side. Also, the date of the construction of Chungju Goguryeo Monument has been variously estimated from the Gwanggaeto the Great after the 5th century to the King Munja of the 6th century. However, since the number '永樂七年' has been confirmed, it is possible that Monument was built in 397 or not far from this.

This study is meaningful in that it applied advanced science technology to history and archaeology and presented a new method to study ancient inscription on a stone monument. If we build an online platform dedicated to Chungju Goguryeo Monument so that researchers can easily access the results, it is expected that more objective and advanced readings will be presented as the usability increases. And there are King Gwanggaeto Monument and Jian Goguryeo Monument, which are the monuments of the Goguryeo period in China. These can also be conducted jointly with Korea and China by applying the latest method developed by NAHF. The issue of awareness of Goguryeo history is emerging as a pending issue. This is a good research project in terms of jointly investigating the resources that Korea and China can share.