• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.78-99
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• 2020

The Buddha triad and 16 Arhat statues carved on the rock surface at Seongbulsa temple is the only domestic remaining example of all 16 Arhats, so its academic value is very high. However, it is severely damaged and so required a stability evaluation through study of digital documentation and precise diagnosis for the purpose of comprehensive conservation. This process established that the Buddha statues were of similar scale, while the Arhats showed a wide variety of sizes, and the two kith and kin in the volume were larger than the Arhats. It was estimated that the statues of food for Buddha are similar to the Arhat statues, and most of the statues are well-formed. The rock used to carve the Buddha statues is banded gneiss with distinct foliation, alternating between white bands of quartz and feldspar and black bands composed of biotite. The Buddha statues have been damaged by physical weathering, discoloration, and biological contamination. In damage evaluations, joint (3.6 crack index), peeling (5.2%), exfoliation (1.7%), and falling off (0.1%) were observed on the rock surface of the Buddha statues. In particular, due to severe biological weathering, stage 9 and 10 biological coverage of the rock surface accounted for 57.5% of the total area, and stages 5 to 8 also accounted for a high share at 22.3%. The discoloration factors were shown to be dark brown and white with Fe, Ca, and S, and a large amount of C detected in the blackened contaminants, and the damage weight high in all areas. Discontinuities in different directions were identified in the rock surface. Analysis of potential rock failure types indicated that there is a possibility of plane and toppling failure, but wedge failure is unlikely to occur. The mean ultrasonic velocity of the main rock surface was 2,463m/sec, the lower part of the left side with a large number of joints was relatively low, and the highly weathered (HW) type to the completely weathered (CW) type concentrated distribution, showing weak properties. For the Buddha statues, conservation treatment is required for about 14.9% of micro cracks and 58.9% of exfoliation cracks. In addition, in order to improve the conservation environment of the Buddha statues, maintenance of drainage and ground preparations for the rock surface gradient and plants are necessary, and protection facilities should be reviewed for long-term conservation and management purposes.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.545-557
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• 2017

The study is about the efficient alternative to concrete surface in the field of visual inspection technology for deteriorated infrastructure. By combining industrial drones and deep learning based image analysis techniques with traditional visual inspection and research, we tried to reduce manpowers, time requirements and costs, and to overcome the height and dome structures. On board device mounted on drones is consisting of a high resolution camera for detecting cracks of more than 0.3 mm, a lidar sensor and a embeded image processor module. It was mounted on an industrial drones, took sample images of damage from the site specimen through automatic flight navigation. In addition, the damege parts of the site specimen was used to measure not only the width and length of cracks but white rust also, and tried up compare them with the final image analysis detected results. Using the image analysis techniques, the damages of 54ea sample images were analyzed by the segmentation - feature extraction - decision making process, and extracted the analysis parameters using supervised mode of the deep learning platform. The image analysis of newly added non-supervised 60ea image samples was performed based on the extracted parameters. The result presented in 90.5 % of the damage detection rate.

• Journal of Conservation Science
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• v.17 s.17
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• pp.39-56
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• 2005

The Gwangtonggyo(bridge) on the Cheonggyecheon(river) is mainly composed of biotite granite with coarse grain. The rock consists mainly of quartz, plagioclase, microcline, orthoclase and biotite with lesser amount of muscovite, sericite and chlorite. Muscovite and sericite may be formed from feldspars and chlorite from biotite by alteration(including weathering). These rocks are relatively deteriorated by weathering, polluted water running the river and heavy traffic. The main phenomena of damages are surface exfoliation, grain separation, deceleration, pollution of organic and heavy chemical elements, cracks and breakage. These phenomena have been analyzed by polarized microscope, XRD and SEM/EDX. The analyzed results show organic pollution and secondarily formed gypsum and apatite on the rock surface and micro-pores. NaCl and $CaCO_3$ as rock salt and calcite probably may be formed secondarily in some points. Also heavy chemical elements such as Cr, Pb, Pd, W, La, Zn and Nd are polluted in some samples. The contacts between rocks are generally breakdown in small scale or cracks are developed due to mainly load and vibration shock of heavy traffic.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.445-451
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• 2017

Because of the supply-demand problem of aggregate, recently, the construction sites using 100% crushed sand are increasing and the use of low quality aggregate such as farmland sand is increasing too. When the low quality aggregate is used, the various quality defect of concrete such as the strength reduction, the increase of shrinkage and bleeding can be occurred. Therefore, in this study, the performance improvement PC admixture was developed to minimize the quality defect of plain concrete of basement parking area, when the low quality aggregate was used at the plain concrete of basement parking area. The slump loss to elapsed time test, the compressive strength test, the bleeding test and the drying shrinkage test were carried out.

• Journal of Conservation Science
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• v.26 no.2
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• pp.121-132
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• 2010

The Bukjiri Maaeyeoraejwasang (National Treasure No. 201) consists of two-mica granite in medium size, which was the simbol of power in the region of the Silla period. Magnetic susceptibility of the host rock was measured as 0.41(${\times}10^{-3}$ SI unit), which has the similar range with surrounding outcrop. The Buddha developed parallel discontinuous plane of NE to SW strike and damaged seriously by exfoliation, granular disintegration and brown discoloration as 41.5%, 16.7% and 40.0%, respectively. As a result of the ultrasonic velocity, which was relatively weak values as 1,629m/s (Buddha area) and 1,549m/s (surrounding outcrop), improved about 900m/s compared to last treatment. From the results of the evaluation for slope stability, identified the possibility of toppling failure in the Buddha, and planar and wedge failure in host rock. Therefore, we suggest for the safely conservation of the Buddha, continuance monitoring for understand behavior of discontinuity system of the surface, and necessitate foundation reinforcement method for the rock which has the danger of collapse.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.355-368
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• 2002

The multi-storied Daewonsa stone pagoda (Treasure No. 1112) in the Sancheong, Korea was studied on the basis of deterioration and geological safety diagnosis. The stone pagoda is composed mainly of granitic gneiss, partly fine-grained granitic gneiss, leucocratic gneiss, biotite granite and ceramics. Each rock of the pagoda is highly exfoliated and fractured along the edges. Some fractures in the main body and roof stones are treated by cement mortar. This pagoda is strongly covered with yellowish to reddish brown tarnish due to the amorphous precipitates of iron hydroxides. Dark grey crust by manganese hydroxides occur Partly, and some Part coated with white grey gypsum and calcite aggregates from the reaction of cement mortar and rain. As the main body, roof and upper part of the pagoda, the rocks are developed into the radial and linear cracks. Surface of this pagoda shows partly yellowish brown, blue and green patchs because of contamination by algae, lichen, moss and bracken. Besides, wall-rocks of the Daewonsa temple and rock aggregates in the Daewonsa valley are changed reddish brown color with the same as those of the pagoda color. It suggests that the rocks around the Daewonsa temple are highly in iron and manganese concentrations compared with the normal granitic gneiss which color change is natural phenomena owing to the oxidation reaction by rain or surface water with rocks. Therefore, for the attenuation of secondary contamination, whitening and reddishness, the possible conservation treatments are needed. Consisting rocks of the pagoda would be epoxy to reinforce the fracture systems for the structural stability on the basements.

• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.405-413
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• 2012

This study demonstrates the consolidation effect of ethylsilicate consolidants considering material characteristics and weathering degree of Samneunggyeseongakyukjonbul(rock-carved Yukjonbul Buddha in Samneung Valley) in Namsan, Gyeongju. The buddha statue is composed of alkali feldspar granite and contains numerous sets of joint with exfoliation and granular disintegration, therefore the statue is necessary to be treated for surface strength. The laboratory and in-situ tests of consolidation effect showed more increase of ultrasonic velocity that KSE 300, a relatively highly concentrated consolidant, performed more increase of ultrasonic velocity and decrease of porosity than others after treatments in weathered granite. And the consolidated rock with OH 100 was more resistant to salt weathering. For the buddha statues, KSE 300 is more applicable to enhance surface strength because it showed higher consolidation effect for long term than OH 100 and the statues has not been weathered by salts.

• Journal of Conservation Science
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• v.26 no.4
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• pp.349-360
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• 2010

The Yeongsheon Sinwoldong three-storied stone pagoda (Treasure No. 465) composed mainly of drusy alkali-granite. The major rock-forming minerals are biotite, quartz, amphiboles, orthoclase and plagioclase. Yellowish brown and black discoloration are formed at the eight sculpture Buddha of the stylobate. A broken rock fragments in the roof material were repaired using epoxy resin and cement mortar in the past. As a result of the infrared thermography analysis from the pagoda, cracks and exfoliation were not serious. Also, P-XRF analysis showed that concentration of Fe (mean 5,599ppm) and S (mean 3,270ppm) were so high in yellowish discoloration parts. Black discoloration area was detected highly Mn (mean 2,155ppm) concentration around the eight sculpture Buddha of the stylobate. The main reason for these are inorganic contaminants from disengaged rock ingredient and organic contaminants from withered plant body. Degree of physical weathering is relatively high in the southern and northern side. The eastern and western side had similar with weathering condition. The northern and eastern side were serious discoloration and biological weathering relatively. Therefore, we suggest that the pagoda need to do cleaning of biological contaminant and conservation treatment to weakened materials of rock and long term monitoring.

• Korean Journal of Heritage: History & Science
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• v.43 no.3
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• pp.4-25
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• 2010

This study was carried out on scientific conservation treatment based on material characteristics, provenance interpretation, and deterioration diagnosis for seven-storied Jungwon Tappyeongri stone pagoda in Chungju. As a result, main rock of the pagoda is biotite granite with magnetite-series (average $5.86{\times}10^{-3}$ SI unit), containing partly basic xenolith, pegmatite veinlet and feldspar phenocryst. As a result of the provenance presumption of the host rock, a rock around the Songgang stream was identified the same origin. Therefore the rock is appropriate for materials of the pagoda restoration. The deterioration assessment suggested that the pagoda was seriously exfoliated (2.7 to 5.5%), discolored (39.8 to 58.9), and contaminated with repair materials (3.5 to 9.4%), and bioorganisms (19.3 to 24.4%). Accordingly, conservation treatment was carried out based on preliminary investigation for stable conservation of the pagoda. Overall processes were sequentially proceeded by restoration of the replacement stone, cleaning, joining and consolidation. This study sets up an integrated conservation system from preliminary investigation to conservation treatment of the pagoda. Also, the study will contribute for establishing the future-oriented customized conservation treatment.

• Korean Journal of Heritage: History & Science
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• v.44 no.3
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• pp.92-111
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• 2011

This study focus on the restoration stone selection of break-out part based on material characteristics analysis and the conservational safety diagnosis using various nondestructive techniques for Jungdong and Banjukdong Stone Auariums. As a result, the original rocks of the stone aquariums body are porphyritic granodiorite with magnetite-series having igneous lineation, microcline phenocryst, veinlet and basic xenolith. As a result of the provenance presumption of the host rock, a rock around Gamgokri area in Nonsan City was identified the genetically same rock. Therefore, the rock is appropriate for restoration materials of the break-out part. The deterioration assessment showed that the stone aquariums were highly serious scaling, scale off and blackening. Particularly, the front face of Banjukdong stone aquarium needs reinforcement of structural crack (760mm) caused from igneous lineation of biotite. Blackening contaminants on the stone aquariums surface occurred by combining iron oxide, manganese oxide and clay mineral. Also, major factors of efflorescence contaminants were identified as calcite (Jungdong stone aquariums) and gypsum (Banjukdong stone aquariums). The physical characteristics of stone aquariums appeared that the original and new stone is third (moderately weathered) and second grade (slightly weathered), respectively. This study sets up an integrated conservation system from material analysis to restoration stone selection and conservational safety diagnosis of Jungdong and Banjukdong stone aquariums.