• The Journal of the Petrological Society of Korea
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• v.8 no.3
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• pp.171-182
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• 1999

The Myeonbongsan caldera, 10.2X8.0 km, developed within older sequences of sedimentary formations and intermediate composition volcanis in the southern Cheongsong area. Volcanic rocks in the caldera block include lower intermediate volcanics, middle tuffaceous sequences and upper silicic ones. The silicic volcanics, which is named Myeonbongsan Tuff, are composed of crystal-rich ash-flow tuff(300 m) , bedded tuff(30 m) and pumice-rich ash-flow tuff(700 m) in ascending order. Several intrusions dominate the early sequences within the caldera. The caldera collapsed in a trapdoor type when silicic ash-flow tuffs erupted fro major vent area in the caldera. Normal faulting along a ring fault system except the southwestern part dropped the tuffs down to the northrase with a maximum displacement of about 820 m. The Myeonbongsan Tuff is just about 1,030 m thick inside the northeastern caldera, with its base not exposed, and southwestward thinning down. Rhyolitic plug and ring dikes are emplaced along the central vent and the caldera margins, and the ring dikes are cut by plutonic stocks in the southeastern and northwestern parts. The caldera volcanism eviscerated the magma chamber by a series of explosive eruptions during which silicic magma was erupted to form the Myeonbongsan Tuff. Following the last ash-flow eruption, collapse of the chamber roof resulted in the formation of the Myeonbongsan caldera, a subcircular trapdoor-type depression subsiding about 820 m deep. After the collapse, stony to flow-banded rhyolites were emplaced as circular plugs and ring dikes along the central vent and the caldera margins respectively. Finally after the intrusions, another plutons were emplaced as stocks outside the caldera.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.96-110
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• 1997

The Wondong Caldera, formed by the voluminous eruption of the rhyolitic ashflows of the Wondong Tuff which is about 1,550 m thick at the intracaldera and 550 m at the outflow, is a resurgent caldera which shows a dome structure on the central exposure of the caldera. The Wondong caldera volcanism eviscerated the magma chamber by a series of explosive eruptions during which rhyolitic magma was ejected, as small fallouts and voluminous ash-flows, to form the Wondong Tuff. The explosive eruptions began with ash-falls, progressed through pumice-falls and transmitted ash-flows. During the ash-flow phase the initial central vent eruption transmitted into late ring-fissure eruption which accompanied with caldera collapse. Contemporaneous collapse of the roop of the chamber resulted in the formation of the Wondong Caldera, a subcircular depression subsiding about 1,930 deep. Following the collapse, quartz porphyry was intruded as ring dykes along the ring fracture near the southwestern caldera rim. Subsequently the central part of the caldera floor began to be uplifted into a circular resurgent dome by the rising of residual magma. Concurrent with the resurgent doming, the volcaniclastic sediments of Hwajeri Formation were accumulated in the caldera moat and then rhyodacite lava erupted from the initial central resurgent dome and another ash-flow tuff from the northern ring fracture. After the sedimentation, the find-grained granodiorite was intruded as an arc along the eastern ring fracture of the caldera. Finally in the central part, the resurgent magma was emplaced as a hornblende biotite granite stock that formed the central dome.

• The Journal of the Petrological Society of Korea
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• v.26 no.4
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• pp.327-339
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• 2017

The Cretaceous Myeongseongsan Granite in the northwestern Gyeonggi Massif consists of a major pale pink-colored biotite monzogranite and a minor white-colored biotite alkaligranite. Low Sr and high Ba concentrations, negative Eu-anomalies in REE plot, negative Sr anomalies in spider diagram, a negative correlation between Sr and Rb, and positive correlations between Sr and Ba and $Eu/Eu^*$ indicate that a fractional crystallization of both plagioclase and K-feldspar played a significant role during magma evolution. The Myeongseongsan Granite is plotted in I-& S-type granites on I, S, A-type granite classification scheme. While the biotite monzogranite is plotted in unfractionated I-& S-type granite, the biotite alkaligranite is plotted in fractionated I-& S-type granite, which indicates that the biotite alkaligranite is a more differentiated product. In order to elucidate the nature of the protoliths of the peraluminous Myeongseongsan magma, we plotted in $Al_2O_3/TiO_2$ vs. $CaO/Na_2O$ and Rb/Sr vs. Rb/Ba diagrams, and they suggest that the Myeongseongsan Granite was derived from clay-poor metagreywackes and meta-psammites or their igneous counterparts. Whole-rock zircon saturation temperature indicates that the Myeongseongsan magma was melted at $740-799^{\circ}C$.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.75-81
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• 2022

Given that China's resource research, exploration and development and resource economy policies are closely related to Korea's industrial competitiveness in the field of global mineral energy resources, it is important to establish the domestic and overseas resource development strategies. In 2020, China will revise and set standards for mineral resources to ensure efficiency in exploration and development and storage management. China's Ministry of Natural Resources has established the National Mineral Resources Plan (2021-2025), aiming to achieve national goals and strategies, and local governments at all levels are also establishing and implementing regional mineral resources plans. As a result, the supervision and management of geological mineral exploration activities have been strengthened, and the safety of industrial production management in the field of geological mineral exploration and development has been strengthened. China has developed guidelines for high-quality geological exploration, surveying and mapping, improved the level of geological mineral exploration and strengthened the mining supervision and management system. According to China's standardization of mineral resources such as solid mineral resources and petroleum gas mineral resources, a new standard system for resource management will be established in China to improve scientific understanding, rational management and utilization.

• Journal of Korean Society of Forest Science
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• v.104 no.4
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• pp.519-526
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• 2015

This study was investigated to analyze stand structure in Daegu Dodong T.orientalis Forest for conservation Thuja orientalis forest. Results of cluster analysis, it was classified to Quercus variabilis group(A), Quercus variabilis-Quercus mongolica group(B), Pinus densiflora group(C), Thuja orientalis group(D). Charaters of location environments for D group were analyzed that altitude 99.3 m, slope $59^{\circ}$, rock exposure 68.3%, BHA $21.8m^2/ha$ and North West aspects. The MRPP-test, It classified groups, appropriately. Importance value of D group was T. orientalis 85.42, Q. variabilis 1.28, P.densiflora 1.30, Fraxinus rhynchophylla 3.56 etc. DBH classes of D group were expressed inverted-J-shaped curve. H' was resulted in 0.600~0.834, H'max 1.317~1.466, J' 0.456~0.594, D' 0.405~0.544. Indecator species Analysis were conducted that woody plants were 4 taxa, Herbal plants 9 taxa.

• The Journal of the Petrological Society of Korea
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• v.23 no.2
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• pp.45-59
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• 2014

This study has been designed to collate distribution, morphology, petrology of columnar joint in South Korea. Reported columnar joint areas in South Korea are 68, until the present time. These can be divided into five group by geography and volcanic activity. 1) The 16 columnar joint areas are distributed in Hantangang region. The 15 areas in this region are composed of basaltic lava in the Quaternary period, and the other 1 area is composed of volcanic rocks in the Cretaceous period. 2) The 18 columnar joint areas are distributed in Jeju island. Most of them are composed of basaltic lava(alkali basalt and Hawaiite), and the Sanbangsan and Baegrokdam area are composed of trachyte in the Quaternary period. Colonnade, entablature and chisel mark of the columnar joint are typically occur in basaltic lava. 3) The 5 columnar joint areas are distributed into the Ulleung island and Dokdo including Guksubawi. These are consisted of relatively well-formed trachyte columns in the Quaternary period. 4) The 8 columnar joint areas are distributed into the Pohang, Gyeongju and Ulsan region and consist of the Tertiary period volcanic rock. It's shape are dome, radial, horizontal and vertical. The 4 columnar joint areas are reported in the Pyeongtaek and Asan city of Chungcheongnamdo and Gosung of Gangwondo. All of them are the Tertiary period basalt. 5) The 15 columnar joint areas are distributed into the west and south coast region. Those are consisted of various rock type(from basalt to dacite), various occurrences(lava flow to welded tuff), and various diameters(20 cm to several meters). The columnar joint of Mudeung mountain and Juwang mountain are welded tuff in the Cretaceous period. The columnar joint is distributed over a wide area in South Korea, 5 in Gangwondo, 13 in Gyeonggido, 2 in Chungnam, 14 in Gyeongbuk, 1 in Jeonbuk, 10 in Jeonnam, 5 in Gyeongnam, and 18 in Jeju. The columnar joints in South Korea can be arranged in order of formative period, 18 in the Cretaceous period, 12 in the Tertiary period, and 38 in the Quaternary period. By magma series, 36 are belong to alkaline series and 32 are belong to sub-alkaline series.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.1-7
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• 1990

Clay mineralogical properties, soil formation and classification for the limestone derived soil were discussed from the 4 soil series, Pyeongchang, Anmi, Yulgog, and Mungyeong, distributed over the area of Bangjeol-Ri, Yeongweol-Eup, Gangweon-Do. The results are as follows; 1. Kaolinite and Al-interlayered vermiculite were the main clay minerals and other minerals were illite, vermiculite, and chlorite. 2. CEC of topsoil ranged from 10.5 to 22.9me/100g and that of sub-soil ranged from 10.0 to 23.8me/100g. CEC seemed to be increased with descending from topograpical position and had slightly significant positive correlation. 3. Lithologic changes as a runction of soil depth showed smooth change for Pyeongchang, discontinuity for Anmi, unpredictability for Yulgog, and uniformity for Mungyeong series. 4. According to the new system of soil taxanomy Pyeongchang series was classified as Typic Hapludalfs, Anmi as Fluventic Eutrochrepts, Yulgog as Fluvaquentic Eutrochrepts, and Mungyeong as Aeric Haplaquepts.

• The Journal of Engineering Geology
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• v.24 no.2
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• pp.247-260
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• 2014

Rock masses at the site for the $2^{nd}$ step construction of the KAERI Underground Research Tunnel (KURT) are divided into six units to establish a rock mechanics model that is dependent on the geological characteristics and degree of joint development. The site primarily consists of three granitic units (G1, G2, and G3), two dykes (D1 and D3), and a fault zone of poor rock mass quality (F3). The F3 unit crosses the tunnel at the beginning of the site of $2^{nd}$ step construction. The rock masses of each unit are classified by RMR (Rock Mass Rating), Q-system, and RMi (Rock Mass Index), all based on borehole logging data. The deformation modulus, rock mass strength, cohesion, and friction angle for each unit are calculated using established empirical relationships. The representative rock mass classification and geotechnical parameters for the rock mass units are established, and a rock mechanics model for the site is proposed, which will be useful in the design and stability analysis of the $2^{nd}$ step construction of KURT.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.229-248
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• 2019

This study was carried out to investigate the flora of Mt. Jaamsan on the Gyeongsang supergroup, Korea. From the results of eight field surveys from March to October 2017, we have identified 530 total taxa, representing 483 species, eight subspecies, 35 varieties, two forms, and two hybrids, which were placed in 325 genera and 110 families. The plant formation of Mt. Jaamsan is the deciduous broad-leaved and conifer mixed forests, which are the common ones in the middle part of the Korean Peninsula. Most of the mountain is covered with young secondary forest, which is mainly composed of Quercus spp., and Pinus. Out of these 530 taxa, 12 are endemic to Korea, 17 taxa are listed on the Korean Red List of threatened species, 65 are floristic target species, and 55 are invasive alien species. The percentage of naturalized index(NI) and urbanization index (UI) were 10.4% and 17.2%, respectively. Mt. Jaamsan has a high plant diversity, including endemic and rare species, which consist of geomorphological landscapes. We considered that the composition and distribution of species are affected by the different environmental factors according to the sedimentary rocks, drying ridges, valleys, and streams. Together with the rocks and soils were the substrate type that play a major role in providing the unique habitats for sun plants in the area.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.277-289
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• 2019

This study was designed to analyze vegetation units using a phytosociological method and to identify the ecological characteristics of each vegetation unit, for forest vegetation from Misiryeong to Danmokryeong of Baekdudaegan, in which, in total, 150 plots were surveyed during May to October 2016. Using community classification according to phytosociology, the Quercus mongolica community group was classified at the top level of a vegetation hierarchy that was classified into an Abies koreana community and a Carpinus cordata community. The A. koreana community was divided into Thuja koraiensis and A. koreana typical groups. The T. koraiensis group was subdivided into Pinus pumila and Betula chinensis subgroups. The C. cordata community was divided into Sasa borealis and C. cordata typical groups. Thus, this forest vegetation comprised one community group, two communities, four groups, and two subgroups and indicated five vegetation units. After analyzing the correlations among the five vegetation units classified by this plant sociological method and the environmental factors like altitude, bare rock, number of present species, and coverage of tree layer with a coincidence method, the A. koreana community and C. cordata typical group were found to be distributed above 1,000 m in altitude, and the S. borealis group was distributed below 1,000 m in altitude. Except for vegetation unit 1, vegetation units tended to be mainly distributed where there was less than 20% bare rock. There was no typical tendency in the number of species present; vegetation unit 5 showed the most abundance among the vegetation units. Coverage by the tree layer mostly exceeded 60%, except for vegetation unit 1.