• Journal of the Korean earth science society
• /
• v.37 no.6
• /
• pp.346-358
• /
• 2016

This study built the volcano Data Base(DB) of 289 active volcanoes around the Korean Peninsula, Japan, China (include Taiwan), and Russia Kamchatka area. Twenty nine more hazardous volcanoes including Baekdusan, Ulleungdo and 27 Japanese volcanoes that can cause a widespread ash-fall on the Korean peninsula by potentially explosive eruption were selected. This selection was based on the presence of volcanic activity, whether or not containing dangerous explosive eruption rock types, distance from Seoul, and volcanoes having Plinian eruption history with volcanic explosivity index (VEI) 4 or more. The results of this study are utilized for screening high-risk volcanoes that may affect the volcanic disaster caused by a widespread fallout ash. By predicting the extent of spread of ash caused by these hazardous volcanic activities and by analyzing the impact on the Korean peninsula, we suggest that it should be used for helping to predict volcanic ash damages and conduct hazards mitigation research as well.

• Earthquakes and Structures
• /
• v.15 no.6
• /
• pp.639-654
• /
• 2018

Rocking motion have been used for achieving the 'resilient buildings' against earthquakes in recent studies. Low-rise buildings, unlike the tall ones, because of their small aspect ratio tend to slide rather than move in rocking mode. However, since rocking is more effective in seismic response reduction than sliding, it is desired to create rocking motion in low-rise buildings too. One way for this purpose is making the building's structure rock on its internal bay(s) by reducing the number of bays at the lower part of the building's skeleton, giving it a mushroom form. In this study 'mushroom skeleton' has been used for creating multi-story rocking regular steel buildings with square plan to rock on its one-by-one bay central lowest story. To show if this idea is effective, a set of mushroom buildings have been considered, and their seismic responses have been compared with those of their conventional counterparts, designed based on a conventional code. Also, a set of similar buildings with skeleton stronger than code requirement, to have immediate occupancy (IO) performance level, have been considered for comparison. Seismic responses, obtained by nonlinear time history analyses, using scaled three-dimensional accelerograms of selected earthquakes, show that by using appropriate 'mushroom skeleton' the seismic performance of buildings is upgraded to mostly IO level, while all of the conventional buildings experience collapse prevention (CP) level or beyond. The strong-skeleton buildings mostly present IO performance level as well, however, their base shear and absolute acceleration responses are much higher than the mushroom buildings.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.11
• /
• pp.7-22
• /
• 2021

In this study, inverse analysis was performed on the bi-directional axial compressive load test conducted on drilled shafts. And the bearing capacities were analyzed by numerical analysis of various pile tip ground conditions of silt clay, silt sand, sand silt, sand gravel, weathered rock, and soft rock. The bearing capacities were analyzed using the P-S method, the Davisson method, and the allowable sttlement of 25.4 mm. The minimum allowable bearing capacities analyzed by three methods were found to be 19.64 MN ~ 24.96 MN. At this time, the base resistances were sharing a 2% ~ 12% of a head load, shaft resistance were shared 88% ~ 98% of the head load. The greater the strength of pile tip was found to increase the allowable bearing capacity. However, the difference between the maximum allowable bearing capacity and the minimum allowable bearing capacity was 5.32 MN, and the increase in the allowable bearing capacity was only 27% depending on the pile tip.

• The Journal of Engineering Geology
• /
• v.20 no.2
• /
• pp.121-126
• /
• 2010

Current technology for radioactive waste disposal facility is operated as part of KURT site characterization in terms of reliability assessment is conducted to expand. In this study, a geological model of KURT surrounding area on the basis of flow characteristics of the site-scale hydrogeological study was about. Distributed in the study area into four boreholes were plotted using the stereo net NS, NW, EW, Low-angle fracture group was able to identify the components of geological models and include top soil layer, belt of weathering, Low-angle fracture zone, fracture zone was divided into. Separated by fracture of the hydraulic test of through the groundwater aquifer that provides the flow hydraulic conductivity and insulation hydraulic affecting the slope of the normal distribution for the size and direction by performing statistical analysis of fracture in the direction of local ns The advantage was confirmed. In addition, Low-angle fracture hydraulic conductivity of the value of 3.61e-07 m/s has a value greater than the major fracture, the fracture zones exist in the base rock and base rock and the hydraulic characteristics of the different methods applied and had to have a different interpretation judged by was.

• Korean Journal of Environment and Ecology
• /
• v.26 no.6
• /
• pp.923-933
• /
• 2012

The purpose of this study targeting Choansan(Mt.) Neighborhood Park in Seoul of South Korea, whose level of visitation and use pressure has been recently increasingly high, was to understand distribution and damage status of forest trail and accordingly, set up direction of how to improve forest trail in urban area. With regards to current damage on forest trail in Choansan(Mt.) Neighborhood Park, the damaged trail with road width of over 2m and with erosion depth of over 30cm amounted to 20.3% and 36.3% respectively. And the trail section with bare land erosion, root exposure or rock exposure and the section whose impact rating class exceeded IV occupied 47.0% and 70.6%, indicating the forest trail was severely damaged. The severely injured trail route mainly included the main forest trail formed along the main ridge, the byroad connected to the main forest trail and the steep forest trail in low-lying area. Based on the study results, five types of restoration of forest trail in Choansan(Mt.) Neighborhood Park were offered, including prevention of forest trail extension, stabilization of forest trail base, maintenance of forest trail surface, vegetation restoration after closing forest trail and maintenance. Ecological restoration was additionally offered. The prevention of forest trail extension was planned to prevent expanded width of forest trail where bare land was exposed. The stabilization of forest trail base was planned to prevent erosion in the forest trail and exposure of roots. The maintenance of forest trail surface was planned in a way to protect the severely damaged forest trail surface by using wood deck and wood stairs and surfacing the road.

• Journal of the Mineralogical Society of Korea
• /
• v.31 no.1
• /
• pp.57-65
• /
• 2018

The geology of Hidalgo state in Mexico is formed by a Precambrian metamorphic rock base which discordantly supports a strong Paleozoic sedimentary rock sequence. Triassic-Jurassic and Cretaceous sedimentary rocks overlie the above-mentioned rocks at a discordant angle. These Mesozoic rocks are in turn covered by a Cenozoic structure which is marine at its base. At the top, the structure changes to andesitic and basaltic composition volcanic rocks. And, a great variety of mineral deposits, both metallic and nonmetallic, is present in Hidalgo state. The host rocks of these deposits are also very varied in age from Mesozoic to Tertiary. Mineralization age corresponds to Tertiary in 90% of the area. Hidalgo state occupies as an important place in national silver and manganese production. Main mineral deposits correspond to argentiferous veins hosted in sedimentary rocks. Following in order of importance are lead and zinc, as well as some small iron deposits. There is evidence of tin and molybdenum mineralization, but these deposits have not been exploited because of their low grade and volume. And, Hidalgo state has different types of nonmetallic mineral deposits such as sedimentary, hydrothermal, metamorphic and volcanic origins.

• Journal of the Geological Society of Korea
• /
• v.54 no.5
• /
• pp.567-578
• /
• 2018

A nondestructive petrological investigation was carried out to identify the original location and form of the Gyeongju Seated Stone Buddha with Square Pedestals in the Blue House (so-called Stone Buddha in the Blue House). The Statue is a representative stone Buddha statue of Silla (9th century) but its original location is controversial and some parts were missing. Based on the petrological observation, magnetic susceptibility and gamma spectrometry, its stone material was identified as medium-grained alkali feldspar granite. This kind of granites are widely found in the Namsan, Gyeongju. It is very likely that the Namsan granites are the source of rock of the Stone Buddha. The Yudeoksa (Igeosaji temple site) and Namsan are possible to be the original home of the Buddha Statue since there are petrologically identical alkali feldspar granite outcrop distributed in Namsan and stone heritage made of the same stone type in both places. An investigation on the square middle stone base in the Chuncheon National Museum reveals that it is less likely to be the missing part of the Buddha statue as the stone base is fine- to medium-grained pink feldspar granite and has different magnetic susceptibility from the Buddha statue. This study confirmed the contribution and significance of petrological investigation to identification of stone heritage in Korea.

• Economic and Environmental Geology
• /
• v.48 no.1
• /
• pp.15-24
• /
• 2015

Extensive base-metal and/or gold bearing ore mineralizations occur in the Pacitan mineralized district of the south western portions in the East Java, Indonesia. Metallic ore bodies in the Pacitan mineralized district are classified into two major types: 1) skarn type replacement ore bodies, 2) fissure filling hydrothermal ore bodies. Skarn type replacement ore bodies are developed typically along bedding planes of limestone as wall rock around the quartz porphyry and are composed mineralogically of skarn minerals, magnetite, and base metal sulfides. Hydrothermal ore bodies differ mineralogically in relation to distance from the quartz porphyry as source igneous rock. Hydrothermal ore bodies in the district are porphyry style Cu-Zn-bearing stockworks as proximal ore mineralization and Pb-Zn(-Au)-bearing fissure filling hydrothermal veins as distal ore mineralization. Sulfur isotope compositions in the sulfides from skarn and hydrothermal ore bodies range from 6.7 to 8.2‰ and from 0.1 to 7.9‰, respectively. The calculated ${\delta}^{34}S$ values of $H_2S$ in skarn-forming and hydrothermal fluids are 0.9 to 7.1‰ (5.6-7.1‰ for skarn-hosted sulfides and 0.9-6.8‰ for sulfides from hydrothermal deposits). The change from skarn to hydrothermal mineralization would have resulted in increased $SO_4/H_2S$ ratios and corresponding decreases in ${\delta}^{34}S$ values of $H_2S$. The calculated ${\delta}^{18}O$ water values are: skarn magnetite, 9.6 and 9.7‰; skarn quartz, 6.3-9.6‰; skarn calcite, 4.7 and 5.8‰; stockwork quartz, 3.0-7.7‰; stockwork calcite, 1.2 and 2.0‰; vein quartz, -3.9 - 6.7‰. The calculated ${\delta}^{18}O_{water}$ values decrease progressively with variety of deposit types (from skarn through stockwork to vein), increasing paragenetic time and decreasing temperature. This indicates the progressively increasing involvement of isotopically less-evolved meteoric waters in the Pacitan hydrothermal system. The ranges of ${\delta}D_{water}$ values are from -65 to -88‰: skarn, -67 to -84‰; stockwork, -65 and -76‰; vein, -66 to -88‰. The isotopic compositions of fluids in the Pacitan hydrothermal system show a progressive shift from magmatic hydrothermal dominance in the skarn and early hydrothermal ore mineralization periods toward meteoric hydrothermal dominance in the late ore mineralization periods.

• International Journal of Highway Engineering
• /
• v.12 no.1
• /
• pp.1-8
• /
• 2010

Construction of road closed to mountains is inevitable in Korea because the mountainous region in Korea is more than 70% in area. Recently, due to global warming, typhoons or heavy rainfalls frequently occur, and accordingly, mountain roads are seriously damaged by landslides, debris flows, and uplift pressure below pavement. in this study, damage on pavement by uplift pressure was investigated. Various influencing factors such as slope angle, reinforcement of slope surface, thickness of soil cover underlain by rock, and types of drainage system were considered to evaluate uplift pressure acting on the bottom of pavement. Raising of water table up to the surface of slope may depend on the duration and intensity of rainfall. It shows that the installation of subdrain can reduce the uplift water pressure. Therefore, It is concluded that the use of subdrain system is effective to decrease uplift pressure and cement treated base is more endurable than typical crushed-stone base.

• Economic and Environmental Geology
• /
• v.34 no.5
• /
• pp.447-460
• /
• 2001

The geothermal waters from the Busan area belong to Na-CI type and are characterized by much higher EC (921 ~6,520${\mu}$S/cm) and TDS (608-3,390 mg/L) than other geothermal waters in Korea. The concentration of majorions shows a weakly positive relationship with temperature except for Mg ion. The concentrations of the major cat ions have the order of Na>Ca>K>Mg. Ca ion is enriched and Mg ion is depleted compared with seawater. All Br concentrations of geothermal water are lower than those of seawater, showing a positive relationship with temperature. Generally geochemical characteristics of geothermal waters of the Busan area indicate that these waters have relatively increased Ca and Sr contents and depleted Mg, Na and K contents caused by seawater interaction with wall rock at depth during deep circulation of seawater. Base on the relationship between major ions and temperature, saline geothermal waters are diluted and are cooled by mixing of groundwaters during ascent. Isotope study and reaction path modeling of the overall geochemical system are required in order to better quantify the evolution and origin of geothermal waters in the Busan area.