• Economic and Environmental Geology
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• v.36 no.4
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• pp.275-284
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• 2003

We collected the samples of stream sediments from primary channels in order to establish natural background of major and minor elements for geologic units in the Gurye area. Stream sediments samples having no possibility of contamination effect and representing drainage basins composed of uniform geology, were collected from April to May in 1999, the chemical analysis of which was carried out. The tolerable level was used to investigate the enrichment degree of harmful elements. The contents of Ni and Cr exceeded the tolerance level in some sections. The tolerance level excess of those elements was regarded as the effect of the metamorphic rock which constituted the bed rock of the area. In order to identify the comprehensive enrichment pattern, the tolerable level was used in calculating the enrichment index. The enrichment index of harmful heavy metals showed that Granite gneiss area is 0.39, Porphyroblastic granite gneiss area 0.32, Biotite gneiss area 0.42, Migmatitic gneiss area 0.41, Tuff area 0.30, Andesite area 0.46, Conglomerate area 0.42, and Granite area 0.26. Those results showed that natural background of Gurye area had not been exposed to harmful heavy metal elements.

• 보존과학연구
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• s.32
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• pp.99-112
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• 2011

The three-storied stone pagoda located in Seungansaji temple site consists mainly of medium to fine-grained biotite granite and granitic gneiss, and partly macrocrystalline gneiss, muscovite gneiss and gabbro. The surface of the stone pagoda is extensively colonized by lichen and moss due to surrounding trees and lawns, and severly deteriorated. Therefore, a comprehensive deterioration diagnosis has been carried out and conservation treatment was conducted in this study. For the conservation treatment, dry cleaning is performed throughout all the surface of the pagoda for naturally grown lichen and biological contaminants using a soft brush and wooden knife. Crustose lichen strongly adhere to the surface was removed by wet cleaning using distilled water. Also, protective railings were reinstalled to an appropriate height with taking the distance from the stone pagoda into account. Finally, the ground around the stone pagoda was repaired with clay sand, and dike was installed with a natural gradient to facilitate water drainage.

• Journal of the Korean Geotechnical Society
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• v.37 no.6
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• pp.21-28
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• 2021

The factors of landslides depend on rainfall intensity, duration, and the characteristics of the soil slope. The conventional slope stability analysis has been carried out by assuming that the slope is saturated. But, a site slope consisting of unsaturated ground must be imitated and interpreted in order to explain a proper behavior of the slope due to rainfall. In this study, by using two major categories of soils in Korea, such as granite and gneiss weathered soils, landslide model test and numerical analysis have been compared with the difference of seepage and volumetric water content. In general, the permeability of gneiss weathered soil, which contains a lot of fines content, is slower than that of granite weathered soil. As a result, in extreme rainfall, numerical analysis can show results that can penetrate quickly, resulting in saturation or more dangerous collapse.

• The Journal of the Petrological Society of Korea
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• v.10 no.2
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• pp.106-120
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• 2001

The Busan area in the northeastern part of the Ogcheon metamorphic zone, Korea, consists mainly of Precambrian Busan and Bakdallyeong gneiss complexes, Ogcheon metamorphic rocks and Mesozoic granitoids. The Busan gneiss complex shows Heart-shaped distribution laying down eastward, and is surrounded by the Ogcheon metamorphic rocks in the central part of the Busan area. In this study structural examination on the main constituent rocks (Busan gneiss complex and Ogcheon metamorphic rocks) was conducted to clarify the geological structure of the Ogcheon metamorphic zone in the Busan area. It indicates that the geological structure was formed at least by three phases of deformation. (1) Dl deformation: the formative period of the structural units of WNW trend (Sanjeoteo, Busan-II, Busan-I, and Chungiu nappes) and the mylonitic foliations related to the compression of NNE-SSW direction, (2) D2 deformation: the differential E-W shortening and N-S extension period of the structural units of WNW trend related to the compression of E-W or WNW-ESE directions, (3) D3 deformation: the formative period of the kink or open folds of E-W trend related to the compression of N-S direction in the eastern and southern parts of Busan area where the structural units of N-S or NNE trends reoriented owing to the intense D2 deformation were developed. These three phases of deformation are closely connected with the distribution of the structural units and the Heart-shaped Busan gneiss complex laying down eastward, and in this paper a new geodynamic model to the Heart-shaped Busan gneiss complex is suggested: Dl deformation-the zonal distribution of WNW trend with a constant width, D2 deformation - the formation of convex wedges northeastward and southward, D3 deformation - the formation of concave wedge westward.

• Economic and Environmental Geology
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• v.41 no.3
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• pp.299-314
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• 2008

The NE-trending Honam shear zone is a broad, dextral strike-slip fault zone between the southern margin of the Okcheon Belt and the Precambrian Yeongnam Massif in South Korea and is parallel to the trend of Sinian deformation that is conspicuous in Far East Asia. In this paper, we report geochemical and isotopic(Sr and Nd) data of mylonitic quartz-muscovite Precambrian gneisses and surrounding foliated hornblende-biotite granitoids near the Myeongho area in the Yecheon Shear Zone, a representative segment of the Honam Shear Zone. Foliated hornblende-biotite granitoids commonly plot in the granodiorite field($SiO_2=61.9-67.1\;wt%$ and $Na_2O+K_2O=5.21-6.99\;wt%$) on $SiO_2$ vs. $Na_2O+K_2O$ discrimination diagram, whereas quartz-muscovite Precambrian orthogneisses plot in the granite field. The foliated hornblende-biotite granitoids are mostly calcic and calc-alkalic and are dominantly magnesian in a modified alkali-lime index(MALI) and Fe# [$=FeO_{total}(FeO_{total}+MgO)$] versus $SiO_2$ diagrams, which correspond with geochemical characteristics of Cordilleran Mesozoic batholiths. The foliated hornblende-biotite granitoids have molar ratios of $Al_2O_3/(CaO+Na_2O+K_2O)$ ranging from 0.89 to 1.10 and are metaluminous to weakly peraluminous, indicating I type. In contrast, Paleoproterozoic orthogneisses have peraluminous compositions, with molar ratios of $Al_2O_3/(CaO+Na_2O+K_2O)$ ranging from 1.11 to 1.22. On trace element spider diagrams normalized to the primitive mantle, the large ion lithophile element(LILE) enrichments(Rb, Ba, Th and U) and negative Ta-Nb-P-Ti anomalies of foliated hornblende-biotite granitoids and mylonitized quartz-muscovite gneisses in the Yecheon Shear Zone are features common to subduction-related granitoids and are also found in granitoids from a crustal source derived from the arc crust of active continental margin. ${\varepsilon}_{Nd}(T)$ and initial Sr-ratio ratios of foliated hornblende-biotite granitoids with suggest the involvement of upper crust-derived melts in granitoid petrogenesis. Foliated hornblende-biotite granitoids in the study area, together with the Yeongju Batholith, show not changing contents of specific elements(Ti, P, Zr, V and Y) from shear zone to the area near the shear zone. These results suggest that no volume changes and geochemical alterations in fluid-rich foliated hornblende-biotite granitoids may occur during deformation, which mass transfer by fluid flow into the shear zone is equal to the mass transfer out of the shear zone.

• The Journal of Engineering Geology
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• v.18 no.1
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• pp.45-54
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• 2008

Based on the data obtained from field investigation and soil testing to slope hazards occurrence section and non-occurrence section in gneiss area, a prediction technique was developed by the use of a decision tree model, which is one of the statistical analysis methods. The slope hazards data of Seoul and Kyonggi Province, which were induced by heavy rainfall in 1998, were 104 sections in gneiss area. The number of data applied in developing prediction model was 61 sections except a vacant value. Among these data, the number of data occurred slope hazards was 34 sections and the number of data non-occurred slope hazards was 27 sections. The statistical analyses using the decision tree model were applied to chi-square statistics, gini index and entrophy index. As the results of analyses, a slope angle, a degree of saturation and an elevation were selected as the classification standard. The prediction model of decision tree using entrophy index is most likely accurate. The classification standard of the selected prediction model is composed of the slope angle, the degree of saturation and the elevation from the first choice stage. The classification standard values of the slope angle, the degree of saturation and elevation are $17.9^{\circ}$, 52.1% and 320 m, respectively.

• 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.23 no.4
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• pp.375-383
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• 2014

Precambrian granitic gneisses and Cambrian meta-sedimentary rocks are prevalently distributed in the eastern part of the Taebaegsan region, and biotite granitic batholith of the Jurassic period (?) is found in the southern part of Uljin-si. But small scale leucocratic granitic stocks which commonly found here and there have been rather neglected in the previous studies. The presence of leucocratic granites could be differentiated from the older granitic rocks and biotite granite through the outcrop characteristics, mineral species and geochemical compositions. For the effective comparison between the older granitic rocks and leucocratic ones, pale gray to gray coloured Hongjesa granitic gneiss with granular texture was selectively chosen. The Hongjesa granitic gneiss and biotite granite usually have rather plenty of coloured minerals such as biotite and chlorites. But the leucocratic granites often show sericitic alteration due to the albitization and greisenisation during the post-magmatic alteration, and shows rather bright appearance because of poor amount of coloured minerals. Since all of granitic rocks passed rather high degrees of magmatic differentiation, they belong to calc-alkalic and peraluminous in their characters. Among the alkali elements of the leucocratic rocks $K_2O$ shows higher increase than those of the other granitic rocks, and $Na_2O$ only represents slight decrease than those of the Hongjesa granitic gneiss and Uljin granite. On the other hand, CaO and total Fe content are clearly decreased than those of the Hongjesa granitic gneiss and Uljin granite.

• Journal of Korean Society of Forest Science
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• v.104 no.4
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• pp.588-597
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• 2015

This study was carried out to identify the reasons of the landslide by land creeping in South Korea in order to provide basic information for establishing the management plan for prevention. Total 29 sites of landslide areas caused by land creeping were observed in South Korea. Among them, the soil-composition of most frequent landslide areas occurred by land creeping was colluvium landslide as 75.9% (22 sites), followed by clay soil landslide as 10.3% (3 sites), bedrock landslide as 6.9% (2 sites), and weathered rock landslide as 6.9% (2 sites). According to the types of parental rocks, the investigated landslide areas were divided into 3 types: 1) metamorphic rocks including schist, phylite, migmatitic gneiss, quartz schist, pophyroblastic gneiss, leucocratic granite, mica schst, banded gneiss and granitic gneiss, 2) sedimentary rocks including limestone, sandstone or shale and mudstone, 3) igneous rocks such as granite, andesite, rhyolite and masanite. As a result, it was noticed that the landslides occurred mostly at the metamorphic rocks areas (13 sites; 44.8%), followed by sedimentary rock areas (12 sites; 41.4%), and igneous rock areas (4 sites; 13.8%). Looking at the direct causes of the landslide, the anthropological activities (71%) such as cut slopes for quarrying, construction of country house, plant, and road, farming of mountain top, and reservoir construction were the biggest causes of the landslides, followed by the land creeping landslides (22%) caused by geological or naturally occurred (22%), and cliff erosions (7%) by caving of rivers and valleys.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.371-379
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• 2008

In this study, seismic elastic wave and dynamic elastic modulus properties are investigated by down-hole seismic tests that were applied to the 11 gneiss area. The research results show that the realtionship between the two properties are $V_s=0.5589{\times}V_p$ in gneiss. The relationship between the two properties are separated into two groups. Group 1 is influenced mainly by the specific gravity of rock, but group 2 is influenced mainly by the joint aperture. As weathering progresses, group 1 clearly shows a decreasing tendency. In fresh and slightly weathered rock-mass, correlations between $V_p$ and dynamic elastic modulus is expressed in linear line but in moderately-highly weathered rock-mass, correlations between $V_p$ and dynamic elastic modulus is expressed curve as a quadratic function. Correlations between $V_s$ and dynamic elastic modulus are analyzed similar with a $V_p$ case.