• Journal of the Korean earth science society
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• v.32 no.6
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• pp.640-653
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• 2011

We simulate the propagation of earthquake waves in the continental margin of Antarctica using the elastic wave modeling algorithm, which is modified to be suitable for acoustic-elastic coupled media and earthquake source. To simulate the various types of earthquake source, the staggered-grid finite-difference method, which is composed of velocity-stress formulae, can be more appropriate to use than the conventional, displacement-based, finite-difference method. We simulate the elastic wave propagation generated by earthquakes combining 3D staggered-grid finite-difference algorithm composed of displacement-velocity-stress formulae with double couple mechanisms for earthquake source. Through numerical tests for left-lateral strike-slip fault, normal fault and reverse fault, we could confirm that the first arrival of P waves at the surface is in a good agreement with the theoretically-predicted results based on the focal mechanism of an earthquake. Numerical results for a model made after the subduction zone in the continental margin of Antarctica showed that earthquake waves, generated by the reverse fault and propagating through the continental crust, the oceanic crust and the ocean, are accurately described.

• Economic and Environmental Geology
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• v.40 no.4
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• pp.473-490
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• 2007

Strata of the Kachi-1 well, Kunsan Basin, offshore western Korea, were analyzed by using integrated stratigraphy approach. As a result, five distinct unconformity-bounded units are recognized in the well: Triassic, Late Jurassic-Early Cretaceous, Early Cretaceous, Late Cretaceous, and Middle Miocene units. Each unit represents a tectono-stratigraphic unit that provides time-sliced information on basin-forming tectonics, sedimentation, and basin-modifying tectonics of the Kunsan Basin. In the late Late Jurassic, development of second- or third-order wrench faults along the Tan-Lu fault system probably initiated a series of small-scale strike-slip extensional basins. Continued sinistral movement of these wrench faults until the Late Cretaceous caused a mega-shear in the basin, forming a large-scale pull-apart basin. However, in the Early Tertiary, the Indian Plate began to collide with the Eurasian Plate, forming a mega-suture zone. This orogenic event, namely the Himalayan Orogeny, continued by late Eocene and was probably responsible for initiation of right-lateral motion of the Tan-Lu fault system. The right-lateral strike-slip movement of the Tan-Lu fault caused the tectonic inversion of the Kunsan Basin. Thus, the late Eocene to Oligocene was the main period of severe tectonic modification of the basin. After the Oligocene, the Kunsan Basin has maintained thermal subsidence up to the present with short periods of marine transgressions extending into the land part of the present basin.

• Economic and Environmental Geology
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• v.47 no.1
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• pp.71-85
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• 2014

To study biogeochemical characteristics and origin organic matter, sediment samples were taken from Site of 1249C and Stie 1251B of ODP Leg 204. Data of Rock-Eval, isotope, and element analysis generally indicate dominance of marine organic matter in sediments deposited under marine sedimentary environment. Only Rock-Eval data are somewhat different from those of others owing to under-maturation of organic matter. Samples of Site 1249C show high content of gas hydrate, whereas Site 1251B low content of gas hydrate in some intervals of the core. This result may be accounted to different location of two cores and presence of transportation passage (Horizon A, BSR 2) of thermogenic gas in the core, 1249 C. However, Site 1251B Located in the basin of low accumulation of gas hydrate is presumed to be limited in the gas hydrate production. Because not only transportation passage is limited to move thermogenic gas from the core, but also gas supply was not enough. Therefore, the biogenic gas that resulted from diagenesis of there sediment is superior.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.358-365
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• 1998

To offer the basic information for sustainable production of forest resources and conservation of the global environment, change in potential natural vegetation (PNV) associated with climate change due to doubling atmospheric carbon dioxide ($2{\times}CO_2$) was estimated with the global natural vegetation mapping system based an K${\ddot{o}}$ppen scheme. The system interpolates climate data spherically to each grid cell, determines the vegetation types onto the grid cell, and produces potential vegetation map and area on the globe and continents. The climate data consist of the current, ($1{\times}CO_2$) climate prior to AD 1958 observed at some 2,000 stations and the doubling ($2{\times}CO_2$) climate estimated from Meteorological Research Institute of Japan. The vegetation zone under the $2{\times}CO_2$ climate scenario expanded mainly toward the poles due to the rise in temperature. The changed PNV area on the globe amounts to 1/3 (4.91 billion (G) ha) of the total land area (15.04 Gha). Kappa statistic for judging agreement between the patterns of vegetation distribution under $1{\times}CO_2$ climate and $2{\times}CO_2$ climates shows good agreement (0.63) for the globe as a whole. The most stable areas are desert and ice. The potential forest area (PFA) was estimated at 6.82 Gha of the land area in $2{\times}CO_2$ climate scenario. In terms of continental changes in PFA, North America and Asis are increased under the $2{\times}CO_2$ climate. However, the potential forest arms of the other continents are decreased by the climate. Europe has no change in the PFA. Especially, the expansion of desert area in Oceania would be accelerated by the $2{\times}CO_2$ climate.

• The Journal of the Petrological Society of Korea
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• v.16 no.2 s.48
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• pp.82-99
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• 2007

The Paleogene dikes intruding into the late Cretaceous granodiorite are pervasively observed in the Irun-myeon, eastern Geoje Island. They are classified into three groups: NW-trending acidic dike swarm and WNW- (A-Group) and $NS{\sim}NNE-trending$ (B-Group) basic dike swarms. Based on their cross-cutting relationships, the earliest is the acidic dike group and fellowed by A- and B-Groups in succession. The acidic dikes seem to have intruded into tension gashes induced by the sinistral strike-slip faulting of the Yangsan fault system during the late $Cretaceous{\sim}early$ Paleogene. In terms of rock-type, orientation, age, and geochemistry, A-Group and B-Group are intimately correlated with the intermediate and basic dike swarms in the Gyeongju-Gampo area, respectively. These results significantly suggest that the corresponding dike swarms are genetically related. Based on the K-Ar and Ar-Ar age data, A- and B- Groups were intruded during $64{\sim}52\;Ma$ and $51{\sim}44\;Ma$, respectively. The result means that the direction of tensional stress in and around the SE Korean peninsula was changed abruptly from NNE-SSW to $EW{\sim}WNW-ESE$ at about 51 Ma. Considering the tectonic environments during the Paleogene, it is interpreted that A-Group was injected along the WNW-trending tensional fractures developed under an regional sinistral simple shear regime which was caused by the north-northwestward oblique subduction of the Pacific plate beneath the Eurasian plate. Meanwhile, the regional stress caused by the collision of India and Eurasia continents at about 55 Ma was likely propagated to the East Asia at about 51 Ma, and then the East Asia including the Korean peninsula was extruded eastwards as a trench-rollback and the dip of downgoing slab of the Pacific plate was abruptly steepened. As a result, the strong suction-force along the plate boundary produced a tensional stress field trending EW or WNW-ESE in and around the Korean peninsula, which resultantly induced B-Group to intrude passively into the study area.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.27-38
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• 1999

The errors between track segments or at the cross-over points of shipborne gravity were successfully reduced by applying a cross-over error adjustment technique using satellite gravity. The integration of shipborne and satellite altimeter-implied free-air gravity anomalies after the cross-over error adjustment resulted in a high resolution gravity map which contains both short and long wavelength components. The successful adjustment of the cross-over errors in the shipborne gravity using the satellite gravity suggests that the shipborne gravity can be combined with the satellite anomalies characterized by a stable and long wavelength component. The resulting free-air anomaly map is evenly harmonized with both short and long wavelength anomalies. Thus the corrected anomaly map can be better used for the geological interpretation. Free-air anomalies with more than 140 mGal in total variations generally correspond to the seafloor topographic changes in their regional patterns. A series of gravity highs are aligned from the Korea Plateau to the Oki Island, which are interpreted to be caused by seamounts or volcanic topographies. The gravity minima along the western and southern shelf edge are associated not only with the local basement morphology and thick sediment fill at the continental margin, but also possibly with the crustal edge effect known for passive continental margins. Series of NE-trending linear anomalies are possibly caused by a swarm of volcanic intrusions followed the initial opening of the Ulleung Basin. The linear high anomalies in the Ulleung Plateau are terminated by the straightly NNW-trending anomalies with a sharp gradient in its western boundary which indicates a fault-line scarp. The opposite side adjoined with the fault-line scarp shows no correlation with the fault-line scarp in geometry indicating that the block might be horizontally slided from the north. A gravity high in contrast to the deepening in seafloor toward the northeastern central Ulleung Basin is probably responsible for the thin crust and shallow seated mantle. The gravity minima along the western and southern shelf edge are associated not only with the local basement morphology and thick sediment fill at the continental margin, but also possibly with the crustal edge effect known for passive continental margins. Series of NE-trending linear anomalies are possibly caused by a swarm of volcanic intrusions followed the initial opening of the Ulleung Basin. The linear high anomalies in the Ulleung Plateau are terminated by the straightly NNW-trending anomalies with a sharp gradient in its western boundary which indicates a fault-line scarp. The opposite side adjoined with the fault-line scarp shows no correlation with the fault-line scarp in geometry indicating that the block might be horizontally slided from the north. A gravity high in contrast to the deepening in seafloor toward the northeastern central Ulleung Basin is probably suggestive of a thin crust and shallow seated mantle.

• Korean Journal of Environment and Ecology
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• v.11 no.1
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• pp.84-99
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• 1997

Amphibian and Reptilian specimens which were surveyed in Gyebangsan during both from Apr. 26, 1995 to Oct. 15, 1995 and from Apr. 13, 1996 to July 28, 1996 were observed 9 Species in 5 Families on 2 Orders and 10 Species in 3 Families, 5 Fimilies, 9 Species and Reptiles were 2 Suborders, 3 Families on 2 Suborders, respectively. Bombina orientalis was revealed dominant species and Bufo stejnegeri was distributed abundant on this investigation area than other survey studies. Relatively large number of larvae of Rana dybowskii were found among the stream and small ponds at the Suchung-gol valley. There were 5 species of Specific wildlife species in Korea as Hynobius leechii, Rana dybowskii, Onchodactylus fischeri, Bufo stejnegeri and Bufo bufo gargarizans. Meanwhile Bufo stejnegeri were endemic species in Korea. 6 Species among 10 Species which were observed Reptiles in this survey Scincella laterale laterale, Dinodon rufozonatus rufozonatus, Agkistrodon brevicaudus, Agkistrodon saxatilis, Amphiesma vibakari ruthveni and Enhydris rufodorsata were Specific wildlife in Korea. Scincella laterale laterale and Takydromus amuriensis were habitated very abundant in Suchung-gol region. Habitat density of Takydromus amureinsis at Suchung-gol region was 36 individuals/ha. Total number of pressed to death individuals caused by press on the road from May to July, 1995 were 404 specimens in 10 Species. The 1,2,3 and 4 Stations where were found the largest number of death individuals caused by press on the road should considered to construct Eco-corridor to reduced the death individuals with small pipes beneath the road as a migration route. Onchodactylus fischeri have around 500m as moving distance and home range for lifelong and it were the climax of broad-leaved tree and highly moisture area that abundantly region of Onchodactylus fischeri.

• Journal of Korean Medical classics
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• v.17 no.4
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• pp.64-68
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• 2004

당(唐)나라 고종시대(高宗時代)(7세기후반기(世紀後半期))에 유행(流行)했던 양상선(楊上善)이 선주(選注)한 "황제내경태소(黃帝內経太素)"가 일본(日本)에 전(傳)해진 것은 현종시대(玄宗時代)(8세기전반기(世紀前半期))였을 것으로 추측된다. 그 후 "태소(太素)"는 중국(中國) 송대(宋代)에는 이미 거의 모두 유실(流失)되었다. 일본(日本)에서도 점차 확실하게 전승(傳承)되지 못했지만 강호시대말기(江戶時代末期)에 이르러 경도(京都)의 인화사(仁和寺) 서고(書庫)에서 재발견(再發見)되었다. 따라서 지금 볼 수 있는 "태소(太素)"에 수록된 내용들은 모두 인화사(仁和寺)에 저장된 고권자초본(古卷子抄本)(이하(以下)에서 인화사본(仁和寺本)이라고 약칭(略稱))으로부터 유래(由來)해온 것이다. 이 초본(抄本)은 1165~1168년(年)에 단파뢰기(丹波頼基)가 직접(直接) 쓴 것이다. 그가 기초로 삼았던 원본은 일세대전(一世代前)의 단파헌기(丹波憲基)가 쓴 것이다. 이에 대하여 살펴본 결과, 인화사본(仁和寺本) "태소(太素)"의 정리(整理)에서 최초에 초사(抄寫)할 때 착오(錯誤)가 있었다는 것을 고려(考慮)할 필요성(必要性)이 일반고의적이상(一般古医籍以上)으로 크다고 말할 수 있으며, "소문(素問), "영추(靈樞)"와의 이동점(異同點)에 대해서도 교기(校記)할 필요(必要)가 없는 것을 응당 지적(指摘)해내야 한다. 그중 상당한 부분(部分)은 옮겨쓴 사람이 일본인이기 때문에 발생한 것이라 할 수 있다. 이런 것들은 일본인(日本人)에 의하여 교정(校正)하는 것이 더 편리(便利)하다고 생각된다. 단지 대륙(大陸)의 문화(文化)가 고대일본(古代日本)에 전입(轉入)되는 과정에서 고대한국인(古代韓國人)의 작용이 컸을 것으로 생각된다. 따라서 "태소(太素)"초본(抄本)에도 "일본적(日本的)인 착오(錯誤)"외에 "고대한국적(古代韓國的)인 착오(錯誤)"가 있을 가능성도 있다. 금후(今後) 이에 대한 많은 연구가 진행되기를 바란다.

• Analytical Science and Technology
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• v.25 no.1
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• pp.7-13
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• 2012

The real-time monitoring of radon ($^{222}Rn$) concentrations has been carried out to evaluate the background concentration level of atmospheric radon in Gosan site, Jeju Island. The mean concentration of radon for the recent 10 years was 2831 $mBq/m^3$ (0.077 pCi/L), which was 19.5 time lower than that of indoor radon in Korea. The seasonal concentrations were 2657, 2071, 3249, 3384 $mBq/m^3$ respectively for spring, summer, fall, and winter seasons. In monthly comparison, the radon concentrations were high in October and low in July. The hourly concentrations have increased during the nighttime, showing 3666 $mBq/m^3$ at 7 a.m., and decreased relatively during the daytime, showing 2755 $mBq/m^3$ at 2~3 p.m. From the back trajectory analysis, the radon concentrations showed higher values when the air mass was moved from the Asia continent to Jeju area, on the other hand, it showed low values when it was moved from the North Pacific Ocean.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.519-533
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• 2012

This study investigates a neotectonic context of the past 5 Ma for the Otway Ranges along the southern Victoria coast, SE Australia by evaluating the distribution and development of marine terraces along the mountainous coastal area. Uplift rate derived from low terrace deposits using OSL dating method is determined to evaluate the extent to which mild intraplate tectonism has the capability to influence the geomorphic evolution of continental interiors. This study also investigates the stratigraphic relationship between Quaternary marine terraces and Pliocene strandlines, which suggests a change of tectonic activity in the Late Neogene. The intensified tectonic response is well addressed in terms of an increase of the Australian intraplate stress level due to the change of relative motion and increased forces in the boundary between the Australian and Pacific plate.