• Journal of Conservation Science
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• v.27 no.4
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• pp.431-440
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• 2011

The thermal expansion coefficient of epoxy/inorganic additives composites was controlled by changing the amount of the inorganic additives such as talc and fused silica. The epoxy resin comprises hydrogenated bisphenol A (HBA)-based epoxide, difunctional polyglycidyl epoxide (DPE) as a diluent and isophorone-diamine (IPDA) as a crosslinking agent, which was subsequently mixed with inorganic additives (talc and fused silica). The thermal expansion coefficient was decreased by increasing amount of inorganic additives, nearly to fresh granite. Fused silica was more effective than talc in lowering the thermal expansion coefficient. Additionally, lexural and tensile strengths of the composites were getting lower and higher with the amount of the inorganic fillers, respectively. It was thus concluded that an epoxy composite containing inorganic fillers was developed to show much lower thermal expansion coefficient, similar to fresh granite, than the neat epoxy resin, and also proper mechanical strengths for applications.

• Journal of Conservation Science
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• v.11 no.1 s.14
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• pp.15-27
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• 2002

The Buddhist Triad Cave in Gunwi, which consists of porphyritic biotite granite, has been deteriorated by a few weatherings. Origin of the weatherings is rain that can be leaked into the cave. Therefore the author investigates a few possible joints and bypasses leaking water, and reinforces any protective schemes for the rain influx. The porphyritic granite around the cave regularly develops two NEE and NWW joint sets. The NEE joint set could be divided into 4 joint zones among which $J_m\;and\;J_3$ may directly affect the leaking water into the cave. A extensional joint, in northern wall of the cave, runs through the $J_m$ joint zone. A small rain could rarely gets through the bypass, but a heavy rain has a good circulation through the joints to be leaked into the cave for a long time because of its long way. Many joints and cracks, in the ceiling near the cave entrance, immediately get to the $J_3$ joint zone, and have a good circulation of a small rain 10 mm. It is the desirable protective schemes that forbid rains to influx along the ranges from L -9 m to +10 m in the $J_m$ joint zone and upper half circle with radius 5 m in the $J_3$ joint zone. The joint apertures should be filled with a petro-epoxy and petro-filler to stop the water flow.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.489-500
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• 2017

It is not rare that pseudotachylite, dark colored rock with glassy texture, is recognizable in deep core samples drilled up to 900 m from the surface. Pseudotachylite with widths varying few to 20 cm is sharply contacted or interlayered with the host rocks composed of Jurassic granite and Precambrian amphibolite gneiss, showing moderately ductile deformation or slight folding. Pseudotachylite occurring at varying depths in the deep drill core are slightly different in texture and thickness. There is evidence of fault gouge at shallower depths, although brittle deformation is pervasive in most drill cores and pseudotachylite is identified at random depth intervals. Under scanning electron microscope (SEM), it is evident that the surface of pseudotachylite is characterized by a smooth, glassy matrix even at micrometer scale and there is little residual fragments in the glass matrix except microcrystals of quartz with embayed shape. Such textural evidence strongly supports the idea that the pseudotachylite was generated through the friction melting related to strong seismic events. Based on X-ray diffraction (XRD) quantitative analysis, it consists of primary minerals such as quartz, feldspars, biotite, amphibole and secondary minerals including clay minerals, calcite and glassy materials. Such mineralogical features of fractured materials including pseudotachylite indicate that the fractured zone might form at low temperatures possibly below $300^{\circ}C$, which implies that the seismic activity related to the formation of pseudotachylite took place at shallow depths, possibly at most 10 km. Identification and characterization of pseudotachylite provide insight into a better understanding of the paleoseismic activity of deep grounds and fundamental information on the stability of candidate disposal sites for high-level radioactive waste.

• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.293-305
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• 2009

The Gilan-Cheongsong area, which is in contact with Yeongyang and Uiseong Blocks of Gyeongsang Basin, Korea, consists of Precambrian metamorphic rocks, Triassic Cheongsong granite, Cretaceous sedimentary rocks(Iljik, Hupyeongdong, Jeomgok Formations), and Cretaceous igneous rocks(andesite, quartz porphyry, felsite). In this area are developed faults trending in (W)NW, NNW, ENE, NS, (N)NE directions which are representative in the Gyeongsang Basin. We analyzed the geometric and kinematic characteristics of fracture systems to inquire into movement history and sense of these faults in this area. This study suggests that these faults were mainly strike-slip movement. The orientations of fracture sets show ENE, NNW, (W)NW, (N)NE, NS in descending order of frequency. Their prolongation presents (W)NW, NNW, ENE, (N)NE, NS in descending order of predominance, and also agrees with that of faults in this area. The development sequence and movement sense of fracture sets are summarized as follows; (1) (W)NW: dextral shearing $\rightarrow$ (2) (W)NW and NNW: conjugate shearing(the former: dextral, the latter: sinistral) $\rightarrow$ (3) NNW: dextral shearing $\rightarrow$ (4) (W)NW: sinistral shearing $\rightarrow$ (5) ENE: dextral shearing $\rightarrow$ (6) ENE and NS: conjugate shearing(the former: sinistral, the latter: dextral) $\rightarrow$ (7) (N)NE: sinistral shearing, and this result is closely associated with the development sequence and movement sense of faults developed in this area.

• The Journal of the Petrological Society of Korea
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• v.19 no.1
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• pp.67-87
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• 2010

This article deal with petrotectonic setting and petrogenesis from petrography and chemical analyses of the Cretaceous volcanic and intrusive rocks in the Cheolwon basin. The volcanic rocks are composed of basalts in Gungpyeong Formation, Geumhaksan Andesite, and rhyolitic rocks (Dongmakgol Tuff, Rhyolite and Jijangbong Tuff), and intrusive rocks, Bojangsan Andesite, granite porphyry and dikes. According to petrochemistry, these rocks represent medium-K to high-K basalt, andesite and rhyolite series that belong to calc-alkaline series, and generally show linear compositional variations of major and trace elements with increase in $SiO_2$ contents, on many Harker diagrams. The incompatible and rare earth elements are characterized by high enrichments than MORB, and gradually high LREE/HREE fractionation and sharp Eu negative anomaly with late strata, on spider diagram and REE pattern. Some trace elements exhibit a continental arc of various volcanic arcs or orogenic suites among destructive plate margins on tectonic discriminant diagrams. These petrochemical data suggest that the basalts may have originated from basaltic calc-alkaline magma of continental arc that produced from a partial melt of upper mantle by supplying some aqueous fluids from a oceanic crust slab under the subduction environment. The andesites and rhyolites may have been evolved from the basaltic magma with fractional crystallization with contamination of some crustal materials. Each volcanic rock may have been respectively erupted from the chamber that differentiated magmas rose sequentially into shallower levels equivalenced at their densities.

• Journal of the Mineralogical Society of Korea
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• v.30 no.1
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• pp.11-19
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• 2017

Reddish brown clay-silt sediments covered granitoid weathering crust in the Jangdongri area, Naju, Korea. Mineralogical and geochemical properties of the ~2 m sediment section were investigated. The sediments were composed mainly of quartz (50%) and clay minerals (45%) with minor contents of K-feldspar, goethite, hematite, and gibbsite. The clay minerals were illite, illite-smectite mixed-layers, vermiculite, hydroxy-Al vermiculite, kaolinite, and halloysite. Mineral composition varied little through the section with the minor upward enrichment of plagioclase and chlorite. Abundant illitic clay minerals indicated the remote source of the sediments because clays derived by granite weathering in Korea were dominated by kaolin minerals. A comparison with the mineral composition of Asian dust (Hwangsa) suggested that plagioclase and K-feldspar disappeared by chemical weathering after deposition, resulting in the quartz and clay-rich sediments. Plagioclase and chlorite altered to kaolin and vermiculite, respectively. Goethite and hematite derived by the weathering of iron-bearing minerals stained the sediment to reddish brown color. The mineralogical and geochemical properties of the reddish brown clay-silt sediments were consistent with those of eolian deposits identified in Korea, supporting eolian origin of the Jangdongri sediments, requiring future confirmation including age dating and isotopic analysis.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.51-55
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• 2013

Among various construction methods, deep soil stabilization by chemical method have been widely used in order to improve soft ground. Dynamic variables using ground(such as sand, weathered granite soil and rock) -structure interaction design affected by dynamic load and cyclic load were studied a lot. However, there is something yet to learn about earthquake resistant design regarding reinforced ground by grout. Therefore, in this study using RC test, the correlation between shear strain and shear modulus with change of water content and injection rate in normal portland cement and clay was compared and analyzed by using Ramberg-Osgood model normalization As the result, dynamic coefficient was considerably affected by water content and grout injection rate.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.487-494
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• 2005

In order to estimated a reason of soil slope failure new measurement technology is demanded to measure a variation of volumetric water content which is a key physical parameter for understanding the slope failure in the field. In this study a laboratory soil tank test were conducted to use RDB and ADR measurement probes for measuring the variation of volumetric water content. These experiments were compared with two physical parameters as volumetric water content and pressure water head which are estimated to the compacted weathered granite soil under the artificial rainfall, 7.5mm/hour, in the whole of two stages. From the results the variation of volumetric water content and pressure water head is represented to nearly similar travel time.

• Journal of the Mineralogical Society of Korea
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• v.26 no.2
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• pp.111-118
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• 2013

Diagenetic black chert nodules occur in the Paleozoic dolostone in Susan, Jecheon, Korea. They reacted with dolomite to form alteration rim around the nodules during the contact metamorphism probably related to the intrusion of biotite granite. In the earlier stage of alteration, talc and calcite replaced both the chert and dolomite, which were subsequently replaced by tremolite. Significant mass of tremolite occurs along the horizon enriched with chert nodules. Scanning electron microscopy and optical microscopy of the tremolite specimens revealed the elongated morphology of diverse aspect ratios coexisting in several mm scale. Non-asbestiform tremolite columns were also common as well as asbestiform fibrous bundles. Quantitative estimation of asbestos should be more cautious for naturally occurring materials because all the tremolite particles in the outcrop are not asbestiform. The occurrence of asbestiform tremolite in the Susan area indicates that a combination of chert-bearing dolostone, heat source, and aqueous fluids is one of the geological environments for the formation of asbestiform tremolite.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.329-337
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• 2019

Bottled water companies in Korea are required to conduct an environmental impact assessment of their drinking water supply at least six months before the expiration of their five-year marketing and production license. The water level drawdown, production well water quality, and monitoring well observation results are the most important items that are evaluated in the assessment report. Here we evaluate the relationship between well drawdown and pumping capacity with pumping time from the production wells of bottled water manufacturers located in Cretaceous granite (site A) and Precambrian gneiss (site B). The method to reduce the pumping capacity is more effective in decreasing the drawdown than the method to simultaneously control the pumping and recovery times. Furthermore, the monitoring data from the pH monitoring sensors that were installed in Precambrian gneiss (site C) yield pH values that increase with time and eventually plateau at a certain value. We therefore propose that pH monitoring is either discontinued or improved to provide more reliable and usable results.