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The Royal Tombs at Songsanri have played considerable roles in the study of Baekje history since the Royal Tomb of King Muryeong was excavated, in untouched condition, in 1971. However, the stability of the Royal Tombs at Songsanri has been threatened by constant exposure to the external environment and infiltration by rainwater. In this study, behavioral monitoring of the walls was conducted using tilt sensors to obtain very precise data about the deformation of the structurally vulnerable walls, evaluate their behavioral characteristics and the influence of environmental changes on these behaviors, and diagnose the structural stability of the ancient tombs. In tomb no. 5, with the exception of relatively rapid behavioral changes attributed to the stabilization process of the tilt sensors, the walls remained stable. However, abnormal changes were observed at several positions in the walls of tomb no. 6 and the Royal Tomb of King Muryeong. These changes were attributed to environmental changes. Furthermore, the abnormal changes in the walls were found to coincide with increases in the soil water content due to rainfall and artificial environmental changes caused by the investigations in the tombs. These findings are expected to be useful in creating policies and designing countermeasures to preserve these historically and culturally valuable tombs.

This study identifies the technique applied for building the rammed earth wall of the 13th Korean fortress, Ganghwa Jungseong, by analyzing its physical, mineralogical, granulometric, and geochemical characteristics. Furthermore, mutual homogeneities between the rammed earth wall and host rock, top soil, and sub-surface soil collected around the fortress were interpreted. The ground of the rammed earth wall was not created artificially but made via soil preparations containing loamy soils from weathered bedrock. The foundation part was built using various layers of soils having different colors, magnetic susceptibilities, particle sizes, and organic components. In particular, a layer of loamy saprolite was generated to enhance the stability of the foundation and improve ventilation and draining throughout the structure. The body of the wall is composed of silty loam at the bottom and silty loam to loam from the middle to the top. Techniques that alternately harden soils using different particle sizes enable external shock absorption and prevent crack formation owing to temperature changes during winter and summer. The rammed earth wall and the soils around the fortress contained related rock-forming materials had similar magnetic susceptibilities and geochemical characteristics, which indicated that they have a genetically common source. Moreover, the rammed earth wall was built using the soil weathered from the banded gneiss because it was correlated to the banded gneiss constituting the bedrock around the fortress.

This study focused on analyzing and calculating the correction factor between direct and indirect methods for the ultrasonic testing of stone monuments using a customized transducer and couplant. To achieve this goal, the P-wave velocity in 11 rock specimens, including two artificially weathered samples, was measured in a laboratory by applying both direct and indirect methods using an ultrasonic tester. Statistical interpretation of the results revealed that the indirect P-wave velocities were always lower than the direct velocities, with the correction factors between them differing by rock type. The average correction factors produced by the indirect method were 1.50 in the medium- to coarse-grained granite sample, 1.37 in fine-grained granite, 1.58 in fine-grained diorite, 1.38 in medium-grained diorite, 1.59 in sandstone, and 1.71 in marble. In addition, the regression equation and coefficient of determination, R 2 were acceptably high, suggesting a sufficient relationship between the two variables for use in engineering. This study will significantly contribute to improving the reliability of ultrasonic testing for weathering evaluation of a stone monument.

This study focused on the quantitative deterioration evaluation for the Magoksa temple stone pagoda of the thirteenth century in Korea, based on the deterioration map by precise observation and ultrasonic velocity measurements. The stone pagoda is composed mainly of fine-grained quartz diorite with some granodiorite used in the second story and dew bowl, and the replacement stone for restoration in the basement is biotite granite. The deterioration map and the 2D contour map projecting ultrasonic velocity showed that the most serious deterioration was to the north face of the pagoda, which has about 81.2% deterioration rate and a low velocity range compared with the other directions. Thus, it is required to prepare conservation schemes to reduce deterioration and reinforce the structure. It is also required to carry out ground exploitation for calculation of load carrying strength and ground strength together with continuous structural monitoring. The results will be important for the stable and long-term conservation of the pagoda and will further serve to establish scientific conservation systems of stone cultural heritages in the future.

This study focuses on the lithological characterization, quantitative deterioration assessment and conservation treatment of the tenth century rock-carved Buddha statues in Korea. The Buddha statues were carved on light gray macrocrystalline biotite granite, and features microcline phenocrysts and pegmatite patches. The rock-forming minerals are quartz, plagioclase, microcline and biotite showing micrographic and porphyritic textures. Feldspars and biotite in the host rock have been partly altered into sericite and chlorite by weathering. The surface of the Buddha statues is remarkably irregular due to granular disintegration and the differential weathering of the quartz and microcline. In addition, horizontal and vertical cracks in the host rock have promoted mechanical weathering. Biological colonization of the statues was serious, and featured dark gray and yellowish green lichen, dark green bryophyte and some plants. The Buddha statues were evaluated as the highly weathered rock by ultrasonic survey. The lower parts under the influence of water and areas with severely broken surfaces showed a much more advanced weathering grade. Therefore, scientific conservation treatment was carried out for the long-term maintenance and conservation of the Buddha statues. After pretests, dry, wet and chemical cleanings were applied to the statues. Next, joining of cracked parts and surface consolidating were executed. Finally, the site environment was improved by installation of drain and trimming trees around the statues to ensure more stable long-term conservation.