• Title/Summary/Keyword: 삼각대

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Petrological study on the intermediate to mafic lavas distributed in Janggi area (1): General geology and petrochemical characteristics (장기 지역에 분포하는 중성~염기성 용암에 관한 암석학적 연구(1): 일반 지질 및 암석화학적 특징)

  • 박주희;김춘식;김진섭;성종규;김인수;이준동;백인성
    • The Journal of the Petrological Society of Korea
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    • v.8 no.3
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    • pp.149-170
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    • 1999
  • The volcanic lavas in the Janggi area are plotted on basalt, basaltic andesite and andesite field (SiO$_2$; 48-61 wt.%) in the TAS diagram and belong to subalkaline series. Nineteen chenmical analyses of lavas show two distinct differentiation trends; tholeiitic and calc-alkaline. Calc-alkaline basaltic andesites composed of plagioclase and two-pyroxenes (cpx, opx) in their phenocrysts. Tholeiitics basaltic lavas can be classified into two sub-types. The one is porphyritic basalts composed of plagioclase, clinopyroxene and olivine phenocryst, and the other is aphyric basalt and more evolved lavas (aphyric basaltic andesite) with the same mineral phases. Incompatible elements and REE patterns show the enrichment of LILE and depletion of HFSE. This characteristics indicate that these lavas are evolved from the magmas related to subduction. Howeverm calc-alkaline basaltic andesite lavas show that slightly higher enrichment of LILE and the depletion of HFSE than those of tholeiitic basaltic lavas. On the tectonic discriminant diagram such as Ba/Th and La/Th ratios, calc-alkaline basaltic andesite lavas belong to orogenic medium to high-K suites, whereas tholeiitic basaltic lavas belong to medium-K suites and MORB. On the other diagram, such as La/Yb vs. Th/Yb, the volcanic lavas in the study area plotted in the field of oceanic arc basalt. Tholeiitic basaltic lavas are located in more prinitive environment than calc-alkaline andesitic lavas.

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Application of nightlight satellite imagery for assessing flooding potential area in the Mekong river basin (메콩강 홍수위험분석을 위한 나이트라이트 위성영상 적용성 검토)

  • Try, Sophal;Lee, Daeup;Lee, Giha
    • Journal of Korea Water Resources Association
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    • v.51 no.7
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    • pp.565-574
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    • 2018
  • High population density in deltaic settings, especially in Asia, tends to increase and causes coastal flood risk because of lower elevations and significant subsidence. Large flood annually causes numerous deaths and huge economic losses. In this paper, an innovative technology of spatial satellite imagery has been used as tool to analyze the socio-economic flood-related damage in Mekong river basin. The relationship between nightlight intensity and flood damages has been determined for the period of 1992-2013 with a spatial resolution of 30 arc sec ($0.0083^{\circ}$), which is nearly one kilometer at the equator. Flow path distance was calculated to identify the distance of each cell to river network and to examine how nightlight intensity correlate to the area close to and far from river network. Statistical analysis results highlight the significant correlation between nocturnal luminosity intensity and flood-related damages in countries along the Mekong river (i.e., Cambodia, China, Lao PDR, Thailand, and Vietnam). This result reveals that the areas close to the river network correspond to high human distribution and causes huge damage during flooding. The result may provide key information to the region with respect to decisions, attentions, and mitigation strategies.

Characteristics of Manganese Nodule from the East Siberian Sea (동시베리아해 망간단괴의 특성)

  • Koo, Hyo Jin;Cho, Hyen Goo;Yoo, Chan Min;Jin, Young Keun
    • Journal of the Mineralogical Society of Korea
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    • v.30 no.4
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    • pp.219-227
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    • 2017
  • Manganese (Mn) nodules in the Arctic Sea have been founded in the Kara Sea and Barents Sea, but mineral and chemical compositions have been rarely investigated. In this study, mineralogical and geochemical characteristics of Mn nodules obtained during the Arctic Expedition ARA07C in northern East Siberian Sea were identified, and then genesis of Mn nodules were estimated by using these characteristics. Main manganese oxide minerals constituting the manganese nodule were buserite, birnessite, and vernadite. The Mn nodules generally represent radiated and massive texture, and the layered texture was developed restrictively. The radiated texture, main feature of the manganese nodule in the East Siberian Sea, is mainly composed of cuspate-globular microstructure. Compared with the Mn nodules in Pacific and Indian Oceans, Mn nodules of the East Siberian Sea are abundant in Mn, but Fe is too scarce. There was no difference in the chemical composition and microstructures between outer and inner part of nodule. Therefore, nodules are most likely to have only one genesis during their growth, and all of nodules indicate the diagenetic in $Mn-Fe-(Cu+Ni+Co){\times}10$ ternary diagram. It is considered that the manganese nodules in the East Siberian Sea are characterized by high Mn contents because manganese contents in the Arctic Ocean were mainly resulted from river or coastal erosion and most of them are trapped in the Arctic Ocean.

Development of Index of Park Derivation to Promote Inclusive Living SOC Policy (포용적 생활 SOC 정책 추진을 위한 공원결핍지수 개발 연구)

  • Kim, Yong-Gook
    • Journal of the Korean Institute of Landscape Architecture
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    • v.47 no.5
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    • pp.28-40
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    • 2019
  • In order to resolve the imbalances in the supply of living SOCs according to socio-economic status, location, and population groups, the discussions on inclusive city policies are expanding. The purpose of this study is to propose an Index of Park Derivation (IPD) as an alternative indicator for the promotion of an inclusive urban park policy that can be applied in the 7 major metropolitan cities to select a region with a relatively high park needs. The main research results are as follows. First, the concept of an inclusive urban park policy is defined as "a policy to supply to manage high-quality park services with priority given to areas with low socio-economic and environmental status, such as a large amount of elderly, children, low-income families, areas vulnerable to disasters, such as heat and fine dust, and population groups." Second, we developed the index of park derivation (IPD), which is a combination of 17 variables including park service level, demographic characteristics, economic and educational level, health level, and environmental vulnerability. The variables that constitute the index of park deprivation (IPD) can be applied to SOC policies outside the parks, such as sports facilities, daycare centers, kindergartens, and public libraries. Third, applying index of park deprivation (IPD) to 1,148 Eup/Myeon/dong areas of the 7 metropolitan cities resulted in areas with relatively high park service needs. This study implies that the central and the local government suggest an alternative index to promote an inclusive urban park policy based on statistical and geographical information and data that can be easily accessed and utilized.

Petrochemistry of the Pink Hornblende Biotite Granite in the Galmal-Yeongbug Area of the North Gyeonggi (경기북부 갈말-영북일대 백악기 홍색 각섬석흑운모화강암의 암석화학)

  • Yun, Hyun-Soo;Hong, Sei-Sun;Kim, Jeong-Min
    • The Journal of the Petrological Society of Korea
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    • v.15 no.4 s.46
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    • pp.167-179
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    • 2006
  • Division of granites in the Galmal-Yeonbug area, northern Gyeonggi, can be grey hornblende biotite granite (JHBG), biotite granite (JBG) and pink hornblende biotite granite (CHBG) by lithofacies. JHBG of small stock occurs as medium-grained with grey color and minute sphene. JBG occurs as medium-grained and light grey to grey in the north-east part of the area. The main study target CHBG covers in the north-southeast part of the area, and occurs medium-to coarse-grained with pink color. CHBG shows partly minute miaroles, and pegmatitic pocket with druse texture. From the mineral age data (K-Ar method). JHBG and JBG and CHBG are the igneous activity products of Daebo orogeny with different Jurassic and Bulgugsa disturbance of Cretaceous, respectively. And the age data also agree with geologic occurrences and interpretations of the granites in the field. CHBG consists of quartz, plagioclase, alkali-feldspar, biotite, hornblende, allanite, apatite, zircon, some calcite and opaques. Among them, alkalifeldspar and calcite occur characteristically in mostly perthitic othoclase and secondary filling of minutely miarolitic cavity, respectively. In modal analysis and QAP diagram, CHBG plots in granite field, and especially boundary of monzo-and syeno-granite fields. From the major oxide variations, molar A/CNK, $SiO_{2}\;vs\;K_{2}O$, AMF and so on, CHBG belongs to the acidic, peraluminous and high-K calc-alkaline, and was late differentiation product of single granitic magma. Barium and strontium have also dominantly differentiation trend, and in CaO vs Sr and $K_{2}O$ vs Sr, Sr was more participitated in the fractionation of plagioclase than that of alkali-feldspar. Normalized REE concentrations to chondrite value have parallel and gradual LREE enrichment and HREE depletion patterns, and weak Eu negative anomalies and narrow ranges of normalized Eu can suggest that plagioclase fractionations occurred mildly in the whole CHBG.

Geochemistry of Granites in the Southern Gimcheon Area of Korea (김천남부에 분포하는 화강암류의 지구화학)

  • 윤현수;홍세선
    • The Journal of the Petrological Society of Korea
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    • v.12 no.1
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    • pp.16-31
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    • 2003
  • The granites in the southern Gimcheon area can be divided into two parts, marginal hornblende biotite granodiorite (Mgd) and central biotite granodiorite to granite (Cgd). Mgd and Cgd are gray in color and display gradational contact relations and are mainly composed of coarse-grained and medium-grained rocks, respectively. Mgd has more frequent and larger mafic enclaves than Cgd, and the two granites partly show parallel foliation at thire contact with gneisses. From representative samples of the granites, K-Ar biotite ages of 197∼207 Ma were obtained. Considering the blocking temperature of biotite, it is suggested that the emplacement age of the granitic magma was probably late Triassic. The anorthite contents of plagioclases in Mgd display less variation than those of Cgd, indicating that Mgd crystallized within a narrow range of temperatures. In the Al$\_$total/-Mg diagram, the biotites from the granites plot within the subalkaline field, and the smooth slope indicates differentiation from a single magma. All amphiboles from the granites belong to magnesio-hornblende. The linear trends of major oxides, AFM and Ba-Sr-Rb indicate that Mgd and Cgd were fractionally differentiated from a single granitic magma body crystallizing from the margin inwards. The relations of modal (Qz+Af) vs. Op, K$_2$O vs. Na$_2$O, Fe$_2$ $O_3$ vs. FeO, Fe$\^$+3/(Fe$\^$+3/+Fe$\^$+2/) and K/Rb vs. Rb/Sr show that they belong to I-type and magnetite-series granitic rocks developed by the progressive melting products of fixed sources. REE data, normalized to chondrite value, have trends of enriched LREE and depleted HREE together with weakly negative Eu anomalies.

Petrochemical Study on the Cretaceous Volcanic Rocks in Kageo island, Korea (가거도(소흑산도)의 백악기 화산암류에 대한 암석화학적 연구)

  • 김진섭;백맹언;성종규
    • The Journal of the Petrological Society of Korea
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    • v.6 no.1
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    • pp.19-33
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    • 1997
  • This study reports the results about the petrography and geochemical characteristics of 10 representative volacanic rocks. The Cretaceous volcanic rocks distributed in the vicinity of the Kageo island composed of andesitic rocks, dacitic welded tuff, and rhyolitic rocks in ascending order. Sedimentary rock is the basement in the study area covered with volcanic rocks. Andesitic rocks composed of pyroclastic volcanic breccia, lithic lapilli tuff and cryptocrystallin lava-flow. Most dacitic rocks are lapilli ash-flow welded tuff. Rhyolitic rocks consists of rhyolite tuff and rhyolite lava flow. Rhyolite tuff are lithic crystal ash-flow tuff and crystal vitric ash-flow tuff with somewhat accidental fragments of andesitic rocks, but dacitic rocks. The variation of major and trace element of the volcanic rocks show that contents of $Al_2O_3$, FeO, CaO, MgO, $TiO_2$ decrease with increasing of $SiO_2$. On the basis of Variation diagrams such as $Al_2O_3$ vs. CaO, Th/Yb vs. Ta/Yb, and $Ce_N/YB_N$ vs. $Ce_N$, these rocks represent mainly differentiation trend of calc-alkaline rock series. On the discriminant diagrams such as Ba/La and La/Th ratio, Rb vs. Y + Nb, the volcanic rocks in study area belongs to high-K Orogenic suites, with abundances of trace element and ternary diagram of K, Na, Ca. According to the tectonic discriminant diagram by Wood, these rocks falls into the diestructructive continental margin. K-Ar ages of whole rocks are from andesite to rhyolite $97.0{\pm}6.8~94.5{\pm}6.6,\68.9{\pm}4.8,\61.5{\pm}4.9~60.7{\pm}4.2$ Ma, repectively. Volcanic rocks in study area show well correlation to the Yucheon Group in terms of rock age dating and geochemcial data, and derived from andesitic calc-alkaline magma that undergone low pressure fractional crystallization dominated plagioclase at <30km.

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A study on the smile of Korean Youth compared with twenty years ago (20년전과 비교한 한국청년의 미소 변화에 관한 연구)

  • Beom, Seung-Gyun;Jung, Ji-Hye;Kim, Tae-Young;Lee, Kyung-Eun;Dong, Jin-Keun
    • The Journal of Korean Academy of Prosthodontics
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    • v.50 no.3
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    • pp.162-168
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    • 2012
  • Purpose: Teeth are generally exposed when people smiling. Moreover, the exposed teeth and soft tissue when smiling becomes an important guideline for esthetically prosthetic restoration. This research is to compare and find out differences of Korean young men's smile living in presence and twenty years ago. Materials and methods: Subjects, 100 young men (50 male and 50 female), were required about several aspects; normally developed physical condition, no psychological or genetic disorders, a fine face with no loss of teeth, no experience in orthodontic or prosthetic treatment, relatively normal occlusion, aged between 20-29. The photos of the subject at rest position and front face when fully smiled were taken three times. 100 photos (50 male and 50 female) were chosen at random from the 240 university students' smile photos taken by Yoon and his colleagues in 1991. By Hulsey's method of measuring smile, several factors; the change of upper lip curvature, the change of the relation between the upper lip and teeth, parallelism between Mx. incisor and lower lip, contact relation between Mx. incisor and lower lip and teeth displayed in a smile, were measured and analyzed. Meanwhile, ten dentists assessed aesthetic evaluation about men and women's smile for twice and recorded and compared smile score. The -test (P<.05) was used to compare the measured value. The difference of smile score was analyzed by t-test (P<.05). Results: The smile score calculated in 2011 (60.22) was higher than that of 1991 (52.80). Among five measurement categories, the noticeable difference was distinguished from two factors; the change of upper lip curvature and contact relation between Mx. incisor and lower lip. Conclusion: The Korean young men's smile has been considerably improved for twenty years. And it is found that the change of upper lip curvature plays an important role, that is, the smile formed with an ascended labial commissure has been increased significantly.

A Preliminary research on Sixth-century Wooden Buddha Images from Funan (6세기 푸난 목조불상에 대한 시론(試論))

  • Noh, Namhee
    • MISULJARYO - National Museum of Korea Art Journal
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    • v.99
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    • pp.10-29
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    • 2021
  • This paper is an introductory study of the wooden Buddha images excavated in the Mekong Delta in present-day southern Vietnam. Approximately thirty examples of wooden Buddha images have been recovered in the Mekong Delta. As they were found among the major historic sites of Funan (the first kingdom in Southeast Asia), including Oc Eo, and likely date to the sixth century, they can be regarded as the works of Funan. Similarly to stone Buddha images, these wooden examples are considered important for their demonstration of aspects of early Buddhist sculpture in Southeast Asia. Most of these Funan wooden Buddha images are presumed to have been produced around the sixth century based on radiocarbon dating and their stylistic characteristics. This paper analyzed the iconography and style of eight examples whose forms are relatively recognizable. The eight images can be divided into four types according to their postures, dress styles, and hand gestures. They all share features of the Sarnath style of the Gupta period in India as seen in their slender bodies and the outer robe that clings to the body. However, some display a South Indian style of Buddha images in their upright posture, style of wearing a monastic robe with the right shoulder exposed, and making the vitarka mudra (preaching gesture) that is often seen in Sri Lankan Buddha images. This suggests that Buddhist sculptors in Funan devised a new style by incorporating the principal styles of Indian Buddhist sculpture. Another notable feature of these Funan images is their material, namely, wood. While none of the contemporaneous Hindu sculptures discovered from the same historic sites are made of wood, numerous Buddhist sculptures are. This paper postulates that the use of wood in Buddhist sculptures was promoted for reasons beyond ease of carving. According to the Buddhist literature, the first-ever Buddha image was the so-called 'Udayana image' made out of sandalwood. This image and its story was well-known in the Southern Dynasty of China around the sixth century. Interestingly, some auspicious sandalwood images of the Buddha was believed to have been brought into the Southern Dynasty from Funan. This suggests the possibility that the legend of the Udayana image might have been known in Funan as well and resulted in the production of wooden sculptures there.

Elemental Composition of Authigenic Siderites in the Early Holocene Coastal Sediments, Western Coast of Korea and Their Depositional Implication (한국 서해 초기현세 퇴적물중 자생 능철석의 원소 성분과 퇴적학적 의미)

  • Cho, J.W.;Lim, D.I.
    • Journal of the Korean earth science society
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    • v.23 no.8
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    • pp.697-706
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    • 2002
  • Authigenic siderite grains, ranging 100 to 250-${\mu}$m in diameter, are abundant in an about 8,600-year-old sediment layer in Namyang Bay, west coast of Korea. The siderites exhibit the aggregated spherulitic morphology with well-developed rhombs on the grain surfaces. They consist mostly of FeCO$_3$ (average, 65%) and MnCO$_3$ (average, 22%) with low Mg/Ca ratio (less than 0.4) in their bulk composition. A series of compositional ternary discrimination diagrams, together with high Mn and low Mg contents, show that only meteoric porewater was involved in siderite precipitation, assuming that depositional environment of host sediment is an organic-rich freshwater system. Considering a series of results such as radiocarbon age, authigenic Mn-rich siderite and lithological features, siderite-hosting sediment (unit Tl) is interpreted as freshwater swamp or bog deposition, infilling the topographic depressions that locally existed before the formation of mid-to-late Holocene tidal deposits. Center-to-margin compositional variation within individual grain is very systematic; Mn and Ca decrease towards the margin of a siderite grain, while Fe and Mg increase. It suggests that the spherulitic siderites were precipitated in this sedimentary layer in a series during the early diagenesis of MnOx-FeOx reduction under steady-state.