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S-wave Velocity Derivation Near the BSR Depth of the Gas-hydrate Prospect Area Using Marine Multi-component Seismic Data (해양 다성분 탄성파 자료를 이용한 가스하이드레이트 유망지역의 BSR 상하부 S파 속도 도출)

  • Kim, Byoung-Yeop;Byun, Joong-Moo
    • Economic and Environmental Geology
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    • v.44 no.3
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    • pp.229-238
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    • 2011
  • S-wave, which provides lithology and pore fluid information, plays a key role in estimating gas-hydrate saturation. In general, P- and S-wave velocities increase in the presence of gas-hydrate and the P-wave velocity decreases in the presence of free gas under the gas-hydrate layer. Whereas there are very small changes, even slightly increases, in the S-wave velocity in the free gas layer because S-wave is not affected by the pore fluid when propagating in the free gas layer. To verify those velocity properties of the BSR (bottom-simulating reflector) depth in the gas-hydrate prospect area in the Ulleung Basin, P- and S-wave velocity profiles were derived from multi-component ocean-bottom seismic data which were acquired by Korea Institute of Geoscience and Mineral Resources (KIGAM) in May 2009. OBS (ocean-bottom seismometer) hydrophone component data were modeled and inverted first through the traveltime inversion method to derive P-wave velocity and depth model of survey area. 2-D multichannel stacked data were incorporated as an initial model. Two horizontal geophone component data, then, were polarization filtered and rotated to make radial component section. Traveltimes of main S-wave events were picked and used for forward modeling incorporating Poisson's ratio. This modeling provides S-wave profiles and Poisson's ratio profiles at every OBS site. The results shows that P-wave velocities in most OBS sites decrease beneath the BSR, whereas S-wave velocities slightly increase. Consequently, Poisson's ratio decreased strongly beneath the BSR indicating the presence of a free gas layer under the BSR.

Stratigraphic response to tectonic evolution of sedimentary basins in the Yellow Sea and adjacent areas (황해 및 인접 지역 퇴적분지들의 구조적 진화에 따른 층서)

  • Ryo In Chang;Kim Boo Yang;Kwak won Jun;Kim Gi Hyoun;Park Se Jin
    • The Korean Journal of Petroleum Geology
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    • v.8 no.1_2 s.9
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    • pp.1-43
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    • 2000
  • A comparison study for understanding a stratigraphic response to tectonic evolution of sedimentary basins in the Yellow Sea and adjacent areas was carried out by using an integrated stratigraphic technology. As an interim result, we propose a stratigraphic framework that allows temporal and spatial correlation of the sedimentary successions in the basins. This stratigraphic framework will use as a new stratigraphic paradigm for hydrocarbon exploration in the Yellow Sea and adjacent areas. Integrated stratigraphic analysis in conjunction with sequence-keyed biostratigraphy allows us to define nine stratigraphic units in the basins: Cambro-Ordovician, Carboniferous-Triassic, early to middle Jurassic, late Jurassic-early Cretaceous, late Cretaceous, Paleocene-Eocene, Oligocene, early Miocene, and middle Miocene-Pliocene. They are tectono-stratigraphic units that provide time-sliced information on basin-forming tectonics, sedimentation, and basin-modifying tectonics of sedimentary basins in the Yellow Sea and adjacent area. In the Paleozoic, the South Yellow Sea basin was initiated as a marginal sag basin in the northern margin of the South China Block. Siliciclastic and carbonate sediments were deposited in the basin, showing cyclic fashions due to relative sea-level fluctuations. During the Devonian, however, the basin was once uplifted and deformed due to the Caledonian Orogeny, which resulted in an unconformity between the Cambro-Ordovician and the Carboniferous-Triassic units. The second orogenic event, Indosinian Orogeny, occurred in the late Permian-late Triassic, when the North China block began to collide with the South China block. Collision of the North and South China blocks produced the Qinling-Dabie-Sulu-Imjin foldbelts and led to the uplift and deformation of the Paleozoic strata. Subsequent rapid subsidence of the foreland parallel to the foldbelts formed the Bohai and the West Korean Bay basins where infilled with the early to middle Jurassic molasse sediments. Also Piggyback basins locally developed along the thrust. The later intensive Yanshanian (first) Orogeny modified these foreland and Piggyback basins in the late Jurassic. The South Yellow Sea basin, however, was likely to be a continental interior sag basin during the early to middle Jurassic. The early to middle Jurassic unit in the South Yellow Sea basin is characterized by fluvial to lacustrine sandstone and shale with a thick basal quartz conglomerate that contains well-sorted and well-rounded gravels. Meanwhile, the Tan-Lu fault system underwent a sinistrai strike-slip wrench movement in the late Triassic and continued into the Jurassic and Cretaceous until the early Tertiary. In the 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 the Tan-Lu fault until the late Eocene caused a megashear in the South Yellow Sea basin, forming a large-scale pull-apart basin. However, the Bohai basin was uplifted and severely modified during this period. h pronounced Yanshanian Orogeny (second and third) was marked by the unconformity between the early Cretaceous and late Eocene in the Bohai basin. In the late Eocene, the Indian Plate began to collide with the Eurasian Plate, forming a megasuture zone. This orogenic event, namely the Himalayan Orogeny, was probably responsible for the change of motion of the Tan-Lu fault system from left-lateral to right-lateral. The right-lateral strike-slip movement of the Tan-Lu fault caused the tectonic inversion of the South Yellow Sea basin and the pull-apart opening of the Bohai basin. Thus, the Oligocene was the main period of sedimentation in the Bohai basin as well as severe tectonic modification of the South Yellow Sea basin. After the Oligocene, the Yellow Sea and Bohai basins have maintained thermal subsidence up to the present with short periods of marine transgressions extending into the land part of the present basins.

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Experimental Models of Schizophrenia (정신분열병의 실험적 모델)

  • Cheon, Jin-Sook
    • Korean Journal of Biological Psychiatry
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    • v.6 no.2
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    • pp.153-160
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    • 1999
  • Animal models can provide a useful tool for the study of some aspects of psychiatric disorders and their treatment. The four criteria for the evaluation of animal models of psychiatric disorders are as following : 1) similarity of inducing conditions 2) similarity of behavioral state 3) common underlying neurobiological mechanisms 4) reversal by clinically effective treatment techniques. Several animal models have been proposed for schizophrenia : phenylethylamine model, L-dopa model, hallucinogen model, cocaine model, amphetamine model, phencyclidine model, noradrenergic reward system lesion model, reticular stimulation model, social isolation model, conditioned avoidance reaction, catalepsy test, paw test, self-stimulation paradigms, latent inhibition paradigms, blocking paradigms, prepulse inhibition of the startle reflex, rodent interaction, social behavior in monkeys, hippocampal damage, high ambient pressure, and models using selective breeding. Among them, animals with bilateral lesion of the hippocampus may provide an adequate animal model for several symptoms of schizophrenia, and ketamine model can reproduce negative symptoms and cognitive deficits as well as positive symptoms of schizophrenia. In conclusion, no model of schizophrenia is entirely representative of the disease, and findings gleaned from model systems must be cautiously interpreted. Furthermore, the process of developing and validating animal models must work in concert with the process to identify reliable measures of human phenomenology.

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Diagnostic Availability of Estrogen Receptor Alpha mRNA on Cervical Cancer Tissue (자궁경부암 조직에서 에스트로겐 수용체 알파 mRNA의 진단적 유용성)

  • Kim, Geehyuk;Yu, Kwangmin;Kim, Jungho;Kim, Seoyong;Park, Sunyoung;Ahn, Sungwoo;Lee, Ji-Young;Kim, Sunghyun;Park, Ho-Hyun;Lee, Dongsup
    • Korean Journal of Clinical Laboratory Science
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    • v.50 no.4
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    • pp.449-456
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    • 2018
  • Cervical cancer is the fourth most frequently diagnosed cancer in women worldwide. In lower Human Development Index countries, it has the second highest incidence and mortality among cancer in women. Therefore, better diagnosis and treatment systems are needed. Among them, estrogen receptor alpha ($ER-{\alpha}$) mRNA expression has been analyzed with RT-qPCR since several studies reported that $ER-{\alpha}$ is necessary in the maturation of the uterus and is related to cervical cancer. In this study, $ER-{\alpha}$ quantitative analysis was performed on various lesions and normal tissue samples. Based on the receiver operating characteristic (ROC) curve, its sensitivity and specificity were 85% and 75%, respectively, showing higher or similar results to those of conventional HPV tests. In addition, its expression level was analyzed with clinical information. With regression analysis, the R square value between the $ER-{\alpha}$ mRNA expression level and menopause status was 0.5041, indicating a strong correlation. This study was performed as part of a pilot study and suggests that $ER-{\alpha}$ is related to carcinogenesis. Future studies will examine other hormones and menopausal factors with a larger sample size.