• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.1-10
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• 2011

Sanbangsan and Yongmuri Beach as geosites are very wide areas, and tourists have accessed them via various courses; hence the need to double the number of geosite signs and disperse them at each point. The signs should read "Sanbangsan lava dome," "Yongmuri tuff ring," and "Relationship between the Sanbangsan lava dome and Yongmuri tuff ring." The contents of the sign should be systemic, simple, and clear because tourists have to read it in a short time. The viewpoint of the research area can be largely divided into Sanbangsan View, Yongmuri Beach View, Sanbangsan, and Yongmuri Beach View. Three of each viewpoint (total of 9 viewpoints) can be placed. In the geosite of Sanbangsan and Yongmuri Beach are 5 sub-theme views including the boundary sheet of Sanbangsan and Yongmuri tuff ring, xenolith basalt, marine pothole, tafoni, and crossed sedimentary layer. These sub-theme views are important in understating not only the geosite but the overall geopark as well, so they should be developed and utilized aggressively.

• The Journal of the Petrological Society of Korea
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• v.28 no.4
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• pp.307-317
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• 2019

Petrological studies were performed on the Sanbangsan lava dome, located in the southwest of Jeju Island Volcanic Field. According to the lava ejection method, it is 'an internal primitive form' that is gradually pushed up and expanded by continuous magma injection from the bottom to the top of the vent and it corresponds to the 'low lava dome'. The rocks are partly plotted in the field of benmoreite, but mostly plotted in the field of trachyte of the Cox et al.(1979) classification diagram, and also mainly plotted in the field of trachyte of Le Maitre et al.(2002) and Zr/TiO₂-Nb/Y classification diagram. Therefore, the expression that described the rock of Sanbangsan lava dome as 'trachy-andesite' should be corrected to 'trachyte'. The volcanic rocks that consists in the Sanbangsan lava dome are trachyte containing normative quartz and shows differentiation trend in the range of 59.75-63.46 wt.% SiO₂.

• Journal of Ecology and Environment
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• v.38 no.1
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• pp.85-93
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• 2015

In 2013, the epidemics of pine wilt disease caused by the pine wood nematodes (Bursaphelenchus xylophilus) resulted in damages to the forests of black pine (Pinus thunbergii Parl.) trees in Jeju Island, Korea. Among the affected trees, an old black pine tree at Cave Temple on Mt. Sanbangsan was included and died due to the prevalence of pine wilt disease. The tree was on Mt. Sanbangsan, which was designated as a National Scenic Place with the Number 77 and was believed to be more than 400 years old in age. By examining the disc of the tree stem obtained from the height of 2 m, we counted the tree rings from 4 different directions and cross-dated the readings by comparing the records of drought simulated from the BROOK Model. Our analysis indicates that the tree seems to have grown since late 1860s. Contrary to the belief of the general public, we can conclude that the age of the tree was estimated to be at maximum 150 years, which means that it was not the same old tree as was shown in the painting of the Tam-Ra-Sun-Ryeok-Do (an old painting book for the Inspection Tour of Jeju Island) published in 1702. Discussion was extended to the life history of the tree in growth and leaning and the measures to protect the tree species from the damages of the pine wilt disease caused by pine wood nematodes.

• Economic and Environmental Geology
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• v.19 no.2
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• pp.153-163
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• 1986

Paleomagnetic and geological studies of volcanic and sedimentary rocks of Jeju Island have been carried out to determine the position of virtual geomagnetic pole(VGP), and to estimate the geological sequence and their age. As a result of paleomagnetic studies, the reversal polarities are measured in the Sanbangsan trachyte and Hwasun formation, and the normal are the rest. In case of normal polarity, the mean values of declination and inclination are $2.3^{\circ}$ and $48.4^{\circ}$, respectively, and the average value of VGP is $85.4^{\circ}N$ and $79.9^{\circ}W$. The locations of VGP's are coincident with those obtained from world-wide Plio-Pleistocene rocks. The Hwasun formation and Seongsan formation which have been known to be sedimented in the similar time in the 2nd-stage of volcanic eruption, possess reversal and normal polarities, respectively. This fact brings about the result that two formations should be separated in a sense of geological sequence. Consequently, the geological sequence of the 2nd-stage of volcanic eruption is Pyoseonri basalt-Seoguipo hawaiite-Hwasun formation-Seongsan formation-Jungmun hawaiite-Sanbangsan trachyte. Referring to the paleomagnetic studies and the previous and present geological studies, Seoguipo formation corresponds to the Gauss normal epoch, the 2nd-stage of volcanic eruption to Matuyama reversed epoch, and the 3rd-, 4th-, and 5th-stages to Brunhes normal epoch. Therefore, the Seoguipo formation is mostly sedimented during late Pliocene and/or presumably extended to the early Pleistocene. The rocks of the 2nd- to 5th-stage are formed later than this.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.2
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• pp.87-97
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• 2020

The compositions of the phenocrystic feldspars of the Sanbangsan trachyte range from labradorite(An_53.6) to andesine(An_35.4), and of the microphenocrysts and laths range from andesine(An_31.2) to oligoclase(An_18.7). Mantled feldspar which forms a thin rim around the phenocrysts and microphenocrysts, is anorthoclase(Or_20.5An_9.4) to sanidine(Or_49.2An_1.4). Phenocrystic plagioclase, which shows a distinct zonal structure, represents an oscillatory zoning in which the An content of the zone repeatedly increases or decreases between andesine (An_39.3) and labradorite (An_51.3) from the core toward the rim, and the rim of the phenocrysts is surrounded by alkali feldspar(Or_31.9-39.4Ab_63.2-57.0An_4.9-3.7), showing the antirapakivi texture. Microphenocryst which does not represent the antirapakivi texture, shows the normal zoning with a decreasing An content (An_36.4→An_25.6) as it moves outward from the center of a crystal. As a result of X-ray mapping of K, Ca, and Na elements for the feldspar phenocrysts representing the typical zonal structure, shows the oscillatory zoning that six zones show the distinctive compositional differences, and the rims are mantled by alkali feldspar to indicate the antirapakivi texture. The groundmass is composed of K-enriched, Ca-poor alkali feldspar. The antirapakivi texture of feldspar which appears in Sanbangsan trachyte, may have been formed in mixing systems as a result of the juxtaposition of near liquidus melt, rich in alkali feldspar components(trachytic magma), with plagioclase phenocrysts and microphenocrysts already crystallized in a more mafic system.

• Economic and Environmental Geology
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• v.27 no.2
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• pp.209-212
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• 1994

Cheju Island was formed by volcanic activity probably related to the inferred geodynamics in the early Quaternary times. Paleostress analysis, in spite of a few fault slip data collected near Sanbangsan trachyte dome (dated 0.87 Ma) represents an extentional tectonic event with the direction ENE-WSW. Joint anayses in the vicinity of Seahwa reveal three extensional tectonic events of directions NW-SE, NE-SW and ENE-WSW. Especially the extensional event with the direction ENE-WSW affected the whole Cheju area during the most recent time.

• Economic and Environmental Geology
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• v.19 no.1
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• pp.25-33
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• 1986

The geology of the Jeju island is characterized by the occurrence of thick voluminous basaltic lava flows and minor trachytic lavas. The land form can be divided topographically into the lava plateau, the shield-shaped Halla volcanic edifice and the parasitic cones whose number is more than 360, which is closely related to the cyclic volcanism of the island. Especially, the trachytic lavas seem to be the latest differentiation products of the cyclic activities and largely classified into two groups (Backlokdam group and Sanbangsan group) on the basis of the occurrence and the petrography. The paleomagnetism and the radiometric age on the two groups of trachyte suggest a lower and an upper time limits of the volcanic stratigraphy of the island. An average age of the trachyte of the Sanbangsan group is $0.733{\pm}0.056m.y.$, and is correlated to a horizon a little lower than the boundary (0.69m.y.) between the Brunches normal epoch and Matuyama reversed epoch. An average age of $0.025{\pm}0.008m.y.$ determined from the Backlokdam trachyte may be corrected to anyone horizon of the Laschamp, or the Lake Biwa, or the Lake Mono excursion. The two groups of trachytes are distributed with the latitude difference of 9'($0.15^{\circ}$), and with age difference of about 0.71 m.y. Assuming that the two trachyte groups were erupted from the same stationary hot spot, the lithosphere comprising the Jeju island is considered to have moved southward with a rate of about 2.3 cm/year.

• Journal of the Speleological Society of Korea
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• v.19 no.20
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• pp.29-62
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• 1989

Cheju Island, which was formed by volcanic activity, is an oval in its shape with the major axis 80km and the minor axis of 40km. The island holds in its heart Mt. Hanala rising 1,950m above the sea. Petrological study of this volcanic island has been made actively by Sang-Man Lee, Chong-Kwang Won and Moon-Won Li. The chronological measurements of the island by Chong-Kwan Won and Moon-Won Lee showed that it is composed of Sanbangsan trachytes and Backlokdam trachytes(25,000 year ago). These reports are based on the chemical analysis and the rediometric chronological measurements on the ground. However, there has been no reports about the inside of caves. We made an (composition) analysis of the inside of Manjang Cave by the fundamental parameter method in X-ray fluorescence spectrometry. The fundamental parameter method in X-ray fluorescence spectrometry is nondestructive analysis. and it enables us to make the values processed by a computer. The results obtained by this methods are as follows: SiO$_2$(49％), $Al_2$O$_3$(17％), Fe$_2$O$_3$(13％), CaO(8.1％), MgO(5.5％), Na2O(3.6％), TiO$_2$(2.1％), $K_2$O(0.86％), P$_2$O$_{5}$(0.28％), and MnO(0.20％) respectively. The data obtained by the fundamental parameter method in X-ray fluorescene was compared with the data provided by Chong-Kwan Won and Moon-Won Lee. Our measurement was made by K-Ar-method in cooperation with T. ITAYA. The samples are of 30,000-420,000 years ago. The composition of the values of our underground analysis with the existing values obtained by the analyses on the ground produced new data about Cehju volcanic island.d.

• Journal of the Speleological Society of Korea
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• v.21 no.22
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• pp.17-56
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• 1990

Cheju Island, which was formed by volcanic activity, is an oval in its shape with the major axis of 80km and the minor axis of 40km. The island holds in its heart Mt. Hanla rising 1,950m above the sea. Petrological study of this volcanic island has been made actively by Sang-Man Lee, Chong-Kwan won and Moon-Won Lee. The chronological measurements of the island by Chong-Kwan Won and Moon-Won Lee showed that it is composed of Sanbangsan trachytes and Backlokdam trachytes(25,000 year ago). These reports are based on the chemical analysis and the rediometric chronological measurements on the ground. However, there has been no reports about the inside of caves. We made an (composition) analysis of the inside of Manjang Cave by the fundamental parameter method in X-ray fluorescence spectrometry. The fundamental parameter method in X-ray fluorescence spectrometry is nondestructive analysis, and it enables us to make the values processed by a computer. The results obtained by this methods are as follows : SiO$_2$(49％), $Al_2$O$_3$(17％), Fe$_2$O$_3$(13％), CaO(8.1％), MgO(5.5％), Na$_2$O(3.6％), TiO$_2$(2.1％), $K_2$O(0.86％), P$_2$O$_{5}$(0.28％), and MnO(0.20％), respectively. The data obtained by the fundamental parameter method in X-ray fluorescence was compared with the data provided by Chong-Kwan and Moon-Won Lee. Our measurement was made by K-Ar-method in cooperation with T.ITAYA. The samples are of 30,000～420,000 year ago. The composition of the values of our underground analysis with the existing values obtained by the analyses on the ground produced new data about Cheju volcanic island.d.

• Korean Journal of Plant Taxonomy
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• v.45 no.2
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• pp.158-168
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• 2015

A study of the genus Pilea in Korea including five taxa was carried out using molecular phylogenetic methods. The majority of members of the genus Pilea in Korea are annual herbs, and they live in moist habitats, flowering in summer and fruiting in autumn. The results of a phylogenetic analysis using nrDNA and cpDNA supported the recognition of P. japonica, P. peploides, and P. taquetii. Pilea taquetii from Mt. Sanbangsan in Jeju was nested within P. hamaoi and P. mongolica clade instead of the P. taquetii clade, with P. taquetii from Mt. Jirisan also separated from the P. taquetii clade. This indicates that the separation is not geographical isolation, but is instead related to taxonomic problems. Therefore, further study of the P. taquetii group is necessary.