• Journal of the Speleological Society of Korea
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• v.34 no.35
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• pp.32-42
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• 1993

The Paektu-san mountains are geographically situated in the Korea strait to the north of the main peninsula, coordinated between the longitudes of W(127$^{\circ}$15'~128$^{\circ}$00')and E(128$^{\circ}$15'~129$^{\circ}$00'), and between the latitudes of S(41$^{\circ}$15'~42$^{\circ}$00') and N(42$^{\circ}$10'~42$^{\circ}$40'). The volcanic group of the Paektu-san mountains can be devided into 2 main kinds of volcanos by the method investigation, The ashes are mainly made of tremolite, trachte, basalt and pumice, or, a little quartz, labradorite and volcanic glass. These sorts, ratios and forms of the rocks are respectively similar. The Haeven lake is surrounded by 19 peaks. The central volcanic cone is a secant cone in shape, with an altitude of the 1800m to 2749,2m (Chang-kun-bong), an average diameter of 10km, and a shape of an ellipse seen high from the plane. They say there were several eruptions in 1668, 1700 and 1702 A. D. The crystal structure of the rock sample collected at the cave of Mt. Paektu-san is monoclinic. The quantitative analysis of the rock samples in the cave is done by using XRF this time. The chemical compositions by XRF fundamamental parameter analysis is : SiO$_2$: 50.72Wt%, TiO = 2.422Wt%, $Al_2$O$_3$= 17.65Wt%, Fe$_2$O$_3$= 9.371Wt%, CaO = 8.711Wt%, MgO = 4.l19Wt%, MnO = 0.l15Wt%, $K_2$O = 1.369Wt%, Na$_2$O : 3.028Wt% and P$_2$O$_{5}$ = 0.365Wt%. The K-Ar age of the rock sample is also determined to be 0.16Ma. This paper describes some problems experienced in dating young volcanic rocks, and then discusses chemical compositions, X-ray fluorescence analyses and the age of the formation of a lava tunnel such as in Mt. Paektu-san.n.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.1
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• pp.16-27
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• 2018

To predict the influence of volcano eruption on agriculture in South Korea we evaluated the dispersal ranges of the volcanic ashes toward the South Korea based on the possibilities of volcano eruption in Mt. Baekdu. The possibilities of volcano eruption in Mt. Baekdu have been still being intensified by the signals including magmatic unrest of the volcano and the frequency of volcanic earthquakes swarm, the horizontal displacement and vertical uplift around the Mt. Baekdu, the temperature rises of hot springs, high ratios of $N_2/O_2$ and $_3He/_4He$ in volcanic gases. The dispersal direction and ranges and the predicted amount of volcanic ash can be significantly influenced by Volcanic Explosivity Index (VEI) and the trend of seasonal wind. The prediction of volcanic ash dispersion by the model showed that the ash cloud extended to Ulleung Island and Japan within 9 hours and 24 hours by the northwestern monsoon wind in winter while the ash cloud extended to northern side by the south-east monsoon wind during June and September. However, the ash cloud may extent to Seoul and southwest coast within 9 hours and 15 hours by northern wind in winter, leading to severe ash deposits over the whole area of South Korea, although the thickness of the ash deposits generally decreases exponentially with increasing distance from a volcano. In case of VEI 7, the ash deposits of Daejeon and Gangneung are $1.31{\times}10^4g\;m^{-2}$ and $1.80{\times}10^5g\;m^{-2}$, respectively. In addition, ash particles may compact close together after they fall to the ground, resulting in increase of the bulk density that can alter the soil physical and chemical properties detrimental to agricultural practices and crop growth.

• Journal of Forest and Environmental Science
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• v.32 no.2
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• pp.196-204
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• 2016

In this study, vegetation succession and the rate of consequent topsoil development were investigated in shallow landslide scars of sedimentary rock slopes covered by volcanic ashes and pumice in Kagoshima prefecture, Japan. Seven shallow landslide scars of different ages were selected as study areas. In the initial period after the occurrence of a shallow landslide, deciduous broad-leaved trees such as Mallotus japonicus or Callicarpa mollis were occupied in the areas. Approximately 30 years after the landslide, evergreen broad-leaved trees such as Cinnamomum japonicum invaded in the areas, already existed present deciduous broad-leaved trees. After 50 years, the summit of the canopy comprised evergreen broad-leaved trees such as Castanopsis cuspidata var. sieboldii and Machilus thunbergii. Moreover, the diversity of vegetation invading the site reached the maximum after 15 years, followed by a decrease and stability in the number of trees. The total basal areas under vegetation increased with time. It was concluded that the vegetation community reaches the climax stage approximately 50 years after the occurrence of a shallow landslide in the study areas, in terms of the Fisher-Williams index of diversity (${\alpha}$) and the prevalence of evergreen broad-leaved trees. Moreover, according to the results of topsoil measurement in the study areas, the topsoil was formed at the rate of 0.31 cm/year. The development of topsoil usually functions to improve the multi-faceted functions of a forest. However, when the increased depth of topsoil exceeds the stability threshold, the conditions for a shallow landslide occurrence are satisfied. Therefore, we indicated to control the depth of topsoil and strengthen its resistance by forest management in order to restrain the occurrence of shallow landslides.

• Journal of the Korean earth science society
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• v.34 no.6
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• pp.515-523
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• 2013

The eastern coast of South Korea is expected to be damaged by volcanic ash when Mt. Baekdusan volcano erupts. Even if the amount of volcanic ash is small, it can be fatal on the agricultural sector withering many plants and causing soil acidification. Thus, in this paper, we aim to estimate agricultural losses caused by the volcanic ash and to visualize them with Google map. To estimate the volcanic ash losses, a damage assessment model is needed. As the volcanic ash hazard depends on the kind of a crops and the ash thickness, the fragility function of damage assessment model should represent the relation between ash thickness and damage rate of crops. Thus, we model the fragility function using the damage rate for each crop of RiskScape. The volcanic ash losses can be calculated with the agricultural output and the price of each crop using the fragility function. This paper also represents the estimated result of the losses in Gangwon province, which is most likely to get damaged by volcanic ashes in Korea. According to the result with gross agricultural output of Gangwon province in 2010, the amount of volcanic ash losses runs nearly 635,124 million wons in Korean currency if volcanic ash is accumulated over four millimeters. This amount represents about 50% of the gross agricultural output of Gangwon province. We consider the damage only for the crops in this paper. However, a volcanic ash fall has the potential to damage the assets for a farm, including the soil fertility and installations. Thus, to estimate the total amount of volcanic ash damage for the whole agricultural sectors, these collateral damages should also be considered.

• Korean Journal of Remote Sensing
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• v.30 no.2
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• pp.303-314
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• 2014

Mt. SAKRAJIMA in southern Kagosima, japan is one of the most active volcanoes in the world. On 18 August 2013, the SAKRAJIMA volcano recently went into the largest scaled eruption with a huge plume of volcanic ash. Therefore, the concern arises if this considerable amount of ashes might flow into the Korea peninsula as well as Japan. In this paper, we performed numeric experiment to analyze how volcanic product resulted from the SAKRAJIMA volcano has impacted on Korea. In order to predict the spread pathway of ash, HYSPLIT model and UM data has been used and 17th September 2013 has been selected as observation date since it is expected that the volcanic ash would flow into the South Korea. In addition, we have detected ash dispersion by using optical Communication, Ocean and Meteorological Satellite- Geostationary Ocean Color Imager (COMS-GOCI) images. As the results, we come to a very satisfactory conclusion that the spread pathway of volcanoes based on HYSPLIT model are matched 63.52 % with ash dispersion area detected from GOCI satellites image.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.293-305
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• 2020

An eruption of Taal Volcano in the Philippines began on January 12, 2020. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) subsequently issued an Alert Level 4, indicating that "a hazardous explosive eruption is possible within hours to days." It was a phreatic eruption and phreatomagmatic eruption from the main crater that spewed ashes to Calabarzon, Metro Manila, some parts of Central Luzon, and Pangasinan in Ilocos Region, resulting in the suspension of classes, work schedules, and flights. By January 26, 2020, PHIVOLCS observed inconsistent, but decreasing volcanic activity in Taal, prompting the agency to downgrade its warning to Alert Level 3. After February 14, Alert status was set to Level 2 because of overall decreasing trend of volcanic activities, but it does not mean that the threat of an eruption has disappeared. In addition, the Alert Level can be raised to Alert Level 3 if there is a symptom of increasing unrest at any time.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.581-588
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• 2013

We developed the three channel lidar system to measure stratospheric aerosols at the Gwangju Institute for Science and Technology (GIST), a suburban site in Republic of Korea. The system provides backscatter coefficient (${\beta}$) at 532 and 1064 nm as well as depolarization ratios (${\delta}$) at 532 nm ($2{\beta}+1{\delta}$) using the doubled Nd:YAG laser wavelength at 532 and 1064 nm. The lidar system is optimized to measure stratospheric aerosols such as volcanic ashes. This paper describes the details of the optical setup, data acquisition system, and analysis method. This study shows an example of measuring stratospheric aerosols emitted by the volcanic eruption which occurred in Mt. Nabro ($13.37^{\circ}$ N, $41.70^{\circ}$ E).

• Korean Journal of Veterinary Research
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• v.36 no.1
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• pp.51-56
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• 1996

Clinical findings of white muscle disease or dystrophia were reported in Hokkaido horses from 1960. This disease was caused by selenium and $\alpha$-tocopherol deficiency. Therefore, this study were conducted to measure serum selenium and $\alpha$-tocopherol levels in Cheju island horses using feedstuffs containing volcanic ashes. The results were as follows : 1. The mean values of serum total selenium and $\alpha$-tocophcrol were $91.90{\pm}49.18ppb$(13.20ppb-193.80ppb) and $0.345{\pm}0.253mg/dl$(0.056mg/dl-1.159mg/dl) in female respectively. There were no significant relation between serum total selenium and $\alpha$-tocopherol levels. 2. 22%(15 of 68) of the horse examined showed selenium levels below 50ppb. 11.8%(8 of 68) showed $\alpha$-tocopherol levels lower than 0.10mg/dl. These results could be useful to diagnose of white muscle disease of Cheju island foals and quality control of feedstuffs of pregnant mares.

• Journal of the Korean Society of Groundwater Environment
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• v.1 no.1
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• pp.33-50
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• 1994

The Hydrogeologic data of 455 water wells comprising geologic log and aquifer test were analyzed to determine hydrogeologic characteristics of the Cheju island. The groundwater. of the Cheju island is occurred in unconsolidated pyroclastic deposits and crinker interbedded in highly jointed basaltic and andesic rocks as high level, basal and parabasal types under unconfined condition. The average transmissivity and specific yield of the aquifer are at about 29,300㎡/day and 0.12 respectively, The total storage of groundwater is estimated about 44 billion cubic meters. Average annual precipitation is about 3,390 million ㎥ among which average recharge is estimated for 1,494 million ㎥ being equivalent 44.1% of total annual precipitation with 638 million ㎥ of runoff and 1,256 million ㎥ of evapotranspiration. Based on groundwater budget analysis, the sustainable yield is about 620 million ㎥(41% of annual recharge)and rest is discharging into the sea. The geologic logs of recently drilled thermal water wells indicate that very low-permeable marine sediments(Sehwa-ri formation) composed of loosely cemented sandy silt derived from mainly volcanic ashes at the 1st stage volcanic activity of the area is situated at the 120${\pm}$68m below sea level. Another low-permeable sedimentary rock called Seogipo-formation which is deemed younger than the former marine sediment is occured at the area covering north-west and western part of the Cheju island at the ${\pm}$70m below sea level. If these impermeable beds art distributed as a basal formation of fresh water zone of the Cheju island, the most of groundwater in the Cheju island will be para-basal type. These formations will be one of the most important hydrogeologic boundary and groundwater occurences in the area.

• Conservation Science in Museum
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• v.12
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• pp.1-7
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• 2011

The seated stone Buddha(Bon5190) of National Museum of Korea initially consisted of some 90 fragments, making it difficult to guess its overall appearance. Under a restoration work which lasted four months, the fragments were joined together, giving shape to a seated Stone Buddha in Bhumisparsa(earth touching) mudra and an associated figure of Bodhisattva missing the face. The statue was made from a single stone block by digging out the center. Traces of lacquer coating and a gilded layer above the lacquer coat were found in various parts. Polarizing microscopy and XRD analysis revealed that the stone was zeolite, a mineral formed through diagenesis of volcanic glassy ashes from trachytic tuff (Nuldaeri) and dacitic tuff (Guryongpo). In Korea, zeolite deposit found mostly in Gyeongsangbuk-do, in places like Yeonil, Guryongpo, Gampo and Ulsan. The restored statue of seated Buddha proved very similar in appearance to the seated stone Buddha of Deoksa Temple in Cheongdo-gun, Gyeongsangbuk-do (housed in Yeongsanjeon Hall). The scroll inside the statue, containing information about the background and circumstances of creation of this Buddhist sculpture, indicates that the monk Seung-ho took part in it as the head sculptor-monk.