• Journal of the Korean earth science society
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• v.21 no.3
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• pp.302-314
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• 2000

Keumseong area in the southern part of the Jecheon city, the Ogcheon Belt, consists of Precambrian Dangdusan Metamorphic Complex, Dori Formation of the Choseon Supergroup, and Jurassic Jecheon Granite. The Dangdusan Metamorphic Complex consists of quartz schist, mica schist. quartzite and pegmatite. The Dori Formation is composed of mainly laminated limestone. The rocks in the study area have been undergone at least three phases of deformations since Paleozoic period. The Dangdusan Metamorphic Complex is outcrop at three areas in the study area, which are exposed along the faults and occurred as inlier within the Dori Formation. Previous authors interpreted the uplift of the Dangdusan Metamorphic Complex by the Dangdusan Fault, but we could not find any evidences related to the Dangdusan Fault. Thus, we interpret the uplift of the Dangdusan Metamorphic Complex due to the D$_2$ Weolgulri and Dangdusan thrusts and post-D$_2$ Jungbodeul, Kokyo and Jungjeonri faults. The uplift of the Busan Metamorphic Complex to the west of the study area was interpreted by ductile deformation. However, the Dangdusan Metamorphic Complex is formed by brittle thrusts and faults in this study. According to deformation sequence, the characters of deformations in the Choseon and Ogcheon suprergroups had been changed from ductile to brittle deformations through the time. Therefore, we interpret the Dangdusan Metamorphic Complex is exposed later than the Busan Metamorphic Complex.

• The Journal of the Petrological Society of Korea
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• v.7 no.3
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• pp.177-189
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• 1998

Proterozoic gneisss complex of the Paju-Gimpo area, Northwestern Gyeonggi Massif, consists of mainly gneiss and schist with locally intercalated quartzite and metamorphic calcareous rocks. Mineral assemblages of the gneiss and schist are classified into two type: sillimanite free (garnet zone) and sillimanite bearing (sillimanite zone) assemblages. In the Goyang area, Kyanite occurs as metastable relict grain in two gneiss samples, in which sillimanite, garnet, biotite, K-feldspar and plagioclase occur. Cordierite bearing mineral assemblages of gneiss are biotite+garnet+sillimanite+cordierite+plagioclase+quartz ($\pm$K-feldspar, muscovite), and represent the upper amphibolite or granulite facies metamorphism. The metamorphic complex has experienced two different regional metamorphism. The prograde metamorphism is a medium-pressure type characteries by kyanite. The peak metamorphic P-T condition of the prograde metamorphism calculated from the kyanite bearing rock is 7.0~9.4 kb and $718~778^{\circ}C$. The retrograde metamorphism, after the prograde metamorphism, is the low-pressure type characteries by occurrence of cordierite. The peak metamorphic P-T condition of later calculated from the cordierite bearing rock is 3.6~5.5 kb and $750~889^{\circ}C$. Together with the occurrence of relict kyanite, garnet+biotite+plagioclase assemblage as relict in the cordierite, and the result of estimated P-T metamorphic conditions indicate a clockwise P-T path.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.157-163
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• 1993

The present study focuses on simulating river profile changes downstream of the Daecheong multipurpose dam by using the computer program HEC-6, which was developed by the United States Army Corps of Engineers. The dam locates at the Keum river, a typical alluvial stream, whose bed material is composed mostly of fine and medium sands. The study reveals that after the completion of dam, a 15 km long reach downstream from the regulatory dam was severely degraded by about 2~3 m. No further severe degradation of this reach is expected, however, because the river-bed of this reach has been well armored since then with gravels and cobbles. Some places in the study reach were degraded locally by 2 m, due mainly to the large-scale gravel mining activities in that reach. On the other hand, a 20 km long reach in downstream study reach is aggraded more or less by 0.5~1 m. Calculation by the computer program HEC-6 is close to measurement for the study river reach. According to the results by HEC-6, the study river reach would remain generally stable in the future, except a few places in the mid-upstream where further river-bed degradation of 1~2 m would occur and a few places in the far downstream where local river-bed aggradations of about 0.5 m would occur.

• The Journal of the Petrological Society of Korea
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• v.5 no.1
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• pp.52-65
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• 1996

Precambrian metamorphic rocks of the Cheongpyeong-Yangpyeong area, central Gyeonggi massif, comprise gneiss, schist, quartzite and amphibolite. Mineral, assemblages of pelitic gneisses are characterized by biotite + cordierite + garnet + sillimanite + K-feldspar + plagioclase + quartz together with minor muscovite, spinel and corundum, and represent the granulite facies metamorphism. In particular, kyanite occurs as fine-grained relict phase inside plagioclase of three gneiss samples. Metamorphic conditions are estimated from garnet-biotite and garnet-cordierite geothermometers in conjunction with garnet-$Al_2SiO_5$-quartz-plagioclase (GASP) and garnet-rutile-$Al_2SiO_5$-ilmenite (GRAIL) geobarometers. They are 700-$850^{\circ}C$ and 3.2-8.3 kbar, and 580-$690^{\circ}C$ and 2.1-3.2 kbar, respectively, when the core and rim compositions of garnet are use. Garnet of the GASP assemblage increases rimward in the Fe and Mn contents but decreases in the Mg content, whereas its Ca content does not vary significantly. Together with the occurrence of relict kyanite and the result of P-T estimates, compositional zoning patterns of garnet indicate a clockwise P-T history. Moreover, the preservation of high-pressure minerals such as kyanite in plagiocalse, even after the medium-pressure granulite facies metamorphis, suggests a rapid change in P-T conditions.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.689-696
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• 2008

The purpose of this study was to evaluate the alkali-silica reactivity for aggregates in Korea according to test methods: accelerated mortar bar test (AMBT) by ASTM C 1260; chemical test by KS F 2545 (ASTM C 289). The results are as follows: The AMBT (ASTM C 1260) results showed that two (2) igneous rocks (two mica granite and felsite), three (3) sedimentary rocks (arkose, red sandstone and shale), two (2) metamorphic rock (slate and vitric tuff), one (1) mineral (quartz) showed more expansion than 0.1% at 14 days. But, some sedimentary rocks and metamorphic rocks expanded more than 0.1% at 28 days even though they were less than 0.1% at 14 days. Therefore, it is necessary to extend the experimental dates more than 14 days to evaluate the possibility of alkali-aggregate reactivity. The chemical test (KS F 2545) results showed that five (5) igneous rocks (andesite, diabase, granite porphyry, muscovite granite and diorite) were indicative of potentially deleterious expansion, while two (2) igneous rocks (diorite porphyry and quartz porphyry) were possible indicative of expansion, and three (3) igneous rocks (biotite granite, two mica granite and felsite) were indicative of innocuous reactivity. The above results showed that the results from chemical method (KS F 2545) and AMBT (ASTM C 1260) had little relationship.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.280-287
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• 1997

This study was carried out to investigate agricultural status and soil fertility of Bonghwang-cheon watershed area which is located at Chodong-myeon, Milyang-si. The acreage of arable land was about 1,209ha, and the population was 3,706 people. Out of total arable land, paddy was 64.4%, upland 19.6% and orchard 16.0%. Chicken was the largest in the number of livestock and poultry, but pig seems to contribute most severly to water pollution. The geology in the lower stream was alluvium but andesite and derivated materials from it were occupied most upland areas. Tuff was scattered in the small area near by the alluvium of Nakdong river, and diorite and granodiorite were located at the low hill and mountains respectivately. The principal paddy soils in the area were Geumgog, Jisan and Imgog series etc of fine loamy on sloped valleys and fans. The Pyeongtaeg series, fine silty family of imperfectly drained on plain was irrigated by Chodong reservoir. The clayey Honam series on alluvium was distributed along the low hill while Gyuam series, coarse silty alluvial soil way close to Nakdong river. In chemical properties of soils, the vinyl house soils were higher in EC, and orchard soils in OM, $P_2O_5$, exchangeable canons than other soils.

• Economic and Environmental Geology
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• v.18 no.3
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• pp.277-288
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• 1985

Mineral composition and grain size analyses of the sandstone from the Early Jurassic Daedong Group distributed in Mungyeong, Daecheon, Kimpo and Yeoncheon areas were made for the study of provenances and depositional environments. The most of the analyses are obtained from Mungyeong area, with some preliminarly works from Daecheon, Kimpo and Yeoncheon areas. All sandstones from the study area are characterized by high content of quartz ranging from 59.8 to 87.2 percent of total constituents. Many of quartz which has rounded dust ring seems to come from aeolian sediments. Content of feldspar is very low except Daecheon area where it ranges from 1.8 to 10.0 percent. Sandstones from Mungyeong, Kimpo and Yeoncheon areas are classified as quartz and quartzose arenite/wacke, while those from Daecheon area are classified as quartzose and lithic arenite/wacke. According to the character of the sandstones, provenance could be quartzose sandstone and quartzite. Results of grain size analysis of C-M and sorting versus skewness suggest that depositional environment seems to be fluvial, while log-probability curve pattern lacustrine environment. It is hard to derive a definite conclusion of sedimentary environment by the grain size analysis.

• The Journal of the Petrological Society of Korea
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• v.26 no.3
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• pp.255-269
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• 2017

Five year term monitoring investigating variation of allochthonous originated gravels are has been conducted in the beach gravel deposit of the Island Dokdo natural reserve which takes purity and uniqueness with enormous attention though a number of areas. The beach gravel deposits near the dock of the Dongdo and near the accommodation facility of the Seodo comprise various types of gravels including basalt, trachyte, and tuff from the Dokdo itself, and granite, rhyolite, gneiss, quartzite, marble, and concrete from elsewhere. The types of the allochthonous gravels on the basis of the study in 2011 and in 2016 shows no difference, so is the ranking of abundance of the allochthonous gravels; granite-concrete-gneiss in turn on the Dongdo, concrete-gneiss-granite in turn on the Seodo. Nevertheless, the relative ratio of the allochthonous gravel area against the total area is decreased. While it is suspected that the disintegrated facility and the influx of material for construction are the main 2 reasons for the contamination by allochthonous gravel, diminished total contamination ratio indicate that supervising allochthonous material has been improved; at least not worse during the 5 years. On the other hand, it is inferred that gradual influence of rockfall also has been made the gravel beach changed. Therefore, consistent rockfall investigation must be inquired.

• Spatial Information Research
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• v.20 no.3
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• pp.39-50
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• 2012

The objective of this study is the quantitative analysis of climate change effects by performing several statistical analyses with hydrometeorological data sets for past 30 years in Geum river watershed. Temperature, precipitation, relative humidity data sets were collected from eight observation stations for 37 years(1973~2009) in Geum river watershed. River level data was collected from Gongju and Gyuam gauge stations for 36 years(1973~2008) considering rating curve credibility problems and future long-term runoff modeling. Annual and seasonal year-to-year variation of hydrometeorological components were analyzed by calculating the average, standard deviation, skewness, and coefficient of variation. The results show precipitation has the strongest variability. Run test, Turning point test, and Anderson Exact test were performed to check if there is randomness in the data sets. Temperature and precipitation data have randomness and relative humidity and river level data have regularity. Groundwater level data has both aspects(randomness and regularity). Linear regression and Mann-Kendal test were performed for trend test. Temperature is increasing yearly and seasonally and precipitation is increasing in summer. Relative humidity is obviously decreasing. The results of this study can be used for the evaluation of the effects of climate change on water resources and the establishment of future water resources management technique development plan.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.459-470
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• 2008

Types of slope failure related to cut slope stability are interpreted through case analyses, and also factors affecting structurally controlled instability investigated, which are developed by geologic structures along a national road No. 25 across the Cheongwon and Boeun-Guns, Chungbuk. Engineering properties such as orientation, persistence, roughness and uniaxial compressive strength of joints are analyzed by square-inventory method in three areas with well-preserved outcrops. The study area is located in Ogcheon folded bet, and are composed of quartz-schist and quartzite in the Midongsan Formation and phyllite in the Ungyori Formation. Flexural beds by folding, schistosity and cleavage besides joints are developed due to slight metamorphism. Various types of joints developed by folding are formed such as strike-parallel, strike-perpendicular, wedge and wrench joint sets by both initially regional and later superposed folding. Factors of slope instability are created by crossing the orientations of joint, cleavage, bedding and slope one another. In the case that the orientation of a slope is coincident with one of beds, factors causing large-scale failure including plane failure are increased greatly. Also in the region that orientations of the slope and bed are crossed each other at high angle, only local and minor failures are shown in the slope.