메뉴 건너뛰기




Volumn 114, Issue 11, 2009, Pages

Very low frequency earthquakes related to small asperities on the plate boundary interface at the locked to aseismic transition

Author keywords

[No Author keywords available]

Indexed keywords

ASPERITY; DIP-SLIP FAULT; EARTHQUAKE; MAGNITUDE; MOMENT TENSOR; PHILIPPINE SEA PLATE; PLATE BOUNDARY; PLATE TECTONICS; SEISMIC MOMENT; SEISMOGRAM; SLIP;

EID: 72049100657     PISSN: 21699313     EISSN: 21699356     Source Type: Journal    
DOI: 10.1029/2008JB006036     Document Type: Article
Times cited : (53)

References (44)
  • 1
    • 0016438538 scopus 로고
    • Possibility of a major earthquake in the Tokai district, Japan and its pre-estimated seismotectonic effects
    • doi:10.1016/0040-1951(75)90011-6
    • Ando, M. (1975), Possibility of a major earthquake in the Tokai district, Japan and its pre-estimated seismotectonic effects, Tectonophysics, 25, 69-85, doi:10.1016/0040-1951(75)90011-6.
    • (1975) Tectonophysics , vol.25 , pp. 69-85
    • Ando, M.1
  • 2
    • 53849119176 scopus 로고    scopus 로고
    • Spatiotemporal distribution of verylow frequency earthquakes in Tokachi-oki near the junction of the Kuril and Japan trenches revealed by using array signal processing
    • Asano, Y., K. Obara, and Y. Ito (2008), Spatiotemporal distribution of verylow frequency earthquakes in Tokachi-oki near the junction of the Kuril and Japan trenches revealed by using array signal processing, Earth Planets Space, 60, 871-875.
    • (2008) Earth Planets Space , vol.60 , pp. 871-875
    • Asano, Y.1    Obara, K.2    Ito, Y.3
  • 3
    • 0037201273 scopus 로고    scopus 로고
    • The slip distribution of the 1946 Nankai earthquake estimated from tsunami inversion using a new plate model
    • doi:10.1016/S0031-9201(02)00044-4
    • Baba, T., Y. Tanioka, P. R. Cummins, and K. Uhira (2002), The slip distribution of the 1946 Nankai earthquake estimated from tsunami inversion using a new plate model, Phys. Earth Planet. Inter., 132, 59-73, doi:10.1016/S0031-9201(02)00044-4.
    • (2002) Phys. Earth Planet. Inter. , vol.132 , pp. 59-73
    • Baba, T.1    Tanioka, Y.2    Cummins, P.R.3    Uhira, K.4
  • 5
    • 0031413223 scopus 로고    scopus 로고
    • On the resolution of the isotropic component in moment tensor inversion
    • Dufumier, H., and L. Rivera (1997), On the resolution of the isotropic component in moment tensor inversion, Geophys. J. Int., 131, 595-606, doi:10.1111/j.1365-246X.1997.tb06601.x. (Pubitemid 127548582)
    • (1997) Geophysical Journal International , vol.131 , Issue.3 , pp. 595-606
    • Dufumier, H.1    Rivera, L.2
  • 7
    • 0001815015 scopus 로고
    • Characteristic earthquake and long-term earthquake forecasts: Implications of central California seismicity
    • edited by F. Y. Cheng and M. S. Sheu, Elsevier, Oxford, U. K.
    • Ellsworth, W. L. (1995), Characteristic earthquake and long-term earthquake forecasts: Implications of central California seismicity, in Urban Disaster Mitigation: The Role of Science and Technology, edited by F. Y. Cheng and M. S. Sheu, pp. 1-14, Elsevier, Oxford, U. K.
    • (1995) Urban Disaster Mitigation: The Role of Science and Technology , pp. 1-14
    • Ellsworth, W.L.1
  • 8
    • 84980201951 scopus 로고
    • Upper mantle P structure on the ocean side of the Japan- Kurile arc
    • Fukao, Y. (1977), Upper mantle P structure on the ocean side of the Japan- Kurile arc, Geophys. J. R. Astron. Soc., 50, 621-642.
    • (1977) Geophys. J. R. Astron. Soc. , vol.50 , pp. 621-642
    • Fukao, Y.1
  • 9
    • 33845612688 scopus 로고    scopus 로고
    • Short-term slow slip and correlated tremor episodes in the Tokai region, central Japan
    • doi:10.1029/2006GL026579
    • Hirose, H., and K. Obara (2006), Short-term slow slip and correlated tremor episodes in the Tokai region, central Japan, Geophys. Res. Lett., 33, L17311, doi:10.1029/2006GL026579.
    • (2006) Geophys. Res. Lett. , vol.33
    • Hirose, H.1    Obara, K.2
  • 10
    • 56449085299 scopus 로고    scopus 로고
    • Three-dimensional seismic velocity structure and configuration of the Philippine Sea slab in southwest Japan estimated by double-difference tomography
    • doi:10.1029/2007JB005274
    • Hirose, F., J. Nakajima, and A. Hasegawa (2008), Three-dimensional seismic velocity structure and configuration of the Philippine Sea slab in southwest Japan estimated by double-difference tomography, J. Geophys. Res., 113, B09315, doi:10.1029/2007JB005274.
    • (2008) J. Geophys. Res. , vol.113
    • Hirose, F.1    Nakajima, J.2    Hasegawa, A.3
  • 11
    • 0029500392 scopus 로고
    • Thermal constraints on the seismogenic portion of the southwestern Japan subduction thrust
    • doi:10.1029/95JB00153
    • Hyndman, R. D., and K. Wang (1995), Thermal constraints on the seismogenic portion of the southwestern Japan subduction thrust, J. Geophys. Res., 100, 15,373-15,392, doi:10.1029/95JB00153.
    • (1995) J. Geophys. Res. , vol.100
    • Hyndman, R.D.1    Wang, K.2
  • 12
    • 34247598456 scopus 로고    scopus 로고
    • A scaling law for slow earthquakes
    • doi:10.1038/nature05780
    • Ide, S., G. C. Beroza, and T. Uchide (2007a), A scaling law for slow earthquakes, Nature, 447, 76-79, doi:10.1038/nature05780.
    • (2007) Nature , vol.447 , pp. 76-79
    • Ide, S.1    Beroza, G.C.2    Uchide, T.3
  • 13
    • 34548020994 scopus 로고    scopus 로고
    • Mechanism of deep low frequency earthquakes: Further evidence that deep non-volcanic tremor is generated by shear slip on the plate interface
    • DOI 10.1029/2006GL028890
    • Ide, S., D. R. Shelly, and G. C. Beroza (2007b), Mechanism of deep low frequency earthquakes: Further evidence that deep non-volcanic tremor is generated by shear slip on the plate interface, Geophys. Res. Lett., 34, L03308, doi:10.1029/2006GL028890. (Pubitemid 47277585)
    • (2007) Geophysical Research Letters , vol.34 , Issue.3
    • Ide, S.1    Shelly, D.R.2    Beroza, G.C.3
  • 14
    • 53749101739 scopus 로고    scopus 로고
    • Bridging the gap between seismically and geodetically detected slow earthquakes
    • doi:10.1029/2008GL034014
    • Ide, S., K. Imanishi, Y. Yoshida, G. C. Beroza, and D. R. Shelly (2008), Bridging the gap between seismically and geodetically detected slow earthquakes, Geophys. Res. Lett., 35, L10305, doi:10.1029/2008GL034014.
    • (2008) Geophys. Res. Lett. , vol.35
    • Ide, S.1    Imanishi, K.2    Yoshida, Y.3    Beroza, G.C.4    Shelly, D.R.5
  • 15
    • 33644759710 scopus 로고    scopus 로고
    • Dynamic deformation of the accretionary prism excites very low frequency earthquakes
    • DOI 10.1029/2005GL025270
    • Ito, Y., and K. Obara (2006a), Dynamic deformation of the accretionary prism excites very low frequency earthquakes, Geophys. Res. Lett., 33, L02311, doi:10.1029/2005GL025270. (Pubitemid 43336987)
    • (2006) Geophysical Research Letters , vol.33 , Issue.2
    • Ito, Y.1    Obara, K.2
  • 16
    • 33745685110 scopus 로고    scopus 로고
    • Very low frequency earthquakes within accretionary prisms are very low stress-drop earthquakes
    • DOI 10.1029/2006GL025883
    • Ito, Y., and K. Obara (2006b), Very low frequency earthquakes within accretionary prism are very low stress-drop earthquakes, Geophys. Res. Lett., 33, L09302, doi:10.1029/2006GL025883. (Pubitemid 43997529)
    • (2006) Geophysical Research Letters , vol.33 , Issue.9
    • Ito, Y.1    Obara, K.2
  • 17
    • 33845340774 scopus 로고    scopus 로고
    • Performance of regional distance centroid moment tensor inversion applied to the 2004 mid-Niigata Prefecture earthquakes, Japan
    • doi:10.1111/j.1365-246X.2006.03109.x
    • Ito, Y., S. Sekiguchi, T. Okada, R. Honda, K. Obara, and S. Hori (2006), Performance of regional distance centroid moment tensor inversion applied to the 2004 mid-Niigata Prefecture earthquakes, Japan, Geophys. J. Int., 167, 1317-1331, doi:10.1111/j.1365-246X.2006.03109.x.
    • (2006) Geophys. J. Int. , vol.167 , pp. 1317-1331
    • Ito, Y.1    Sekiguchi, S.2    Okada, T.3    Honda, R.4    Obara, K.5    Hori, S.6
  • 18
    • 33846576514 scopus 로고    scopus 로고
    • Slow earthquakes coincident with episodic tremors and slow slip events
    • DOI 10.1126/science.1134454
    • Ito, Y., K. Obara, K. Shiomi, S. Sekine, and H. Hirose (2007), Slow earthquakes coincident with episodic tremors and slow slip events, Science, 315, 503-506, doi:10.1126/science.1134454. (Pubitemid 46175751)
    • (2007) Science , vol.315 , Issue.5811 , pp. 503-506
    • Ito, Y.1    Obara, K.2    Shiomi, K.3    Sekine, S.4    Hirose, H.5
  • 19
    • 0037831199 scopus 로고    scopus 로고
    • Low-frequency continuous tremor around the Moho discontinuity away from volcanoes in the southwest Japan
    • doi:10.1029/2002GL015981
    • Katsumata, A., and N. Kamaya (2003), Low-frequency continuous tremor around the Moho discontinuity away from volcanoes in the southwest Japan, Geophys. Res. Lett., 30(1), 1020, doi:10.1029/2002GL015981.
    • (2003) Geophys. Res. Lett. , vol.30 , Issue.1 , pp. 1020
    • Katsumata, A.1    Kamaya, N.2
  • 20
    • 0009405137 scopus 로고    scopus 로고
    • On the real-time monitoring of the long-period seismic wavefield
    • Kawakatsu, H. (1998), On the real-time monitoring of the long-period seismic wavefield, Bull. Earthquake Res. Inst. Univ. Tokyo, 73, 267-274.
    • (1998) Bull. Earthquake Res. Inst. Univ. Tokyo , vol.73 , pp. 267-274
    • Kawakatsu, H.1
  • 21
    • 2542638085 scopus 로고    scopus 로고
    • High pore fluid pressure may cause silent slip in the Nankai Trough
    • DOI 10.1126/science.1096535
    • Kodaira, S., T. Iidake, A. Kato, J. Park, T. Iwasaki, and Y. Kaneda (2004), High pore fluid pressure may cause silent slip in the Nankai Trough, Science, 304, 1295-1298, doi:10.1126/science.1096535. (Pubitemid 38697420)
    • (2004) Science , vol.304 , Issue.5675 , pp. 1295-1298
    • Kodaira, S.1    Iidaka, T.2    Kato, A.3    Park, J.-O.4    Iwasaki, T.5    Kaneda, Y.6
  • 22
    • 0037037755 scopus 로고    scopus 로고
    • NIED seismic moment tensor catalogue for regional earthquakes around Japan: Quality test and application
    • DOI 10.1016/S0040-1951(02)00375-X, PII S004019510200375X
    • Kubo, A., E. Fukuyama, H. Kawai, and K. Nonomura (2002), NIED seismic moment tensor catalogue for regional earthquakes around Japan: Quality test and application, Tectonophysics, 356, 23-48, doi:10.1016/S0040-1951(02)00375-X. (Pubitemid 35198141)
    • (2002) Tectonophysics , vol.356 , Issue.1-3 , pp. 23-48
    • Kubo, A.1    Fukuyama, E.2    Kawai, H.3    Nonomura, K.4
  • 23
    • 0036624037 scopus 로고    scopus 로고
    • Characteristic smallearthquake sequence off Sanriku, northeastern Honshu
    • doi:10.1029/2001GL014632
    • Matsuzawa, T., T. Igarashi, and A. Hasegawa (2002), Characteristic smallearthquake sequence off Sanriku, northeastern Honshu, Japan, Geophys. Res. Lett., 29(11), 1543, doi:10.1029/2001GL014632.
    • (2002) Japan, Geophys. Res. Lett. , vol.29 , Issue.11 , pp. 1543
    • Matsuzawa, T.1    Igarashi, T.2    Hasegawa, A.3
  • 24
    • 0034957684 scopus 로고    scopus 로고
    • Crustal velocity field of southwest Japan: Subduction and arc-arc collision
    • Miyazaki, S., and K. Heki (2001), Crustal velocity field of southwest Japan: Subduction and arc-arc collision, J. Geophys. Res., 106(B3), 4305-4326, doi:10.1029/2000JB900312. (Pubitemid 32608603)
    • (2001) Journal of Geophysical Research B: Solid Earth , vol.106 , Issue.3 , pp. 4305-4326
    • Miyazaki, S.1    Heki, K.2
  • 25
    • 21844443999 scopus 로고    scopus 로고
    • Geometry of the seismic Philippine Sea slab beneath the region from Ise Bay to western Shikoku, southwest Japan
    • in Japanese with English abstract
    • Miyoshi, T., and K. Ishibashi (2004), Geometry of the seismic Philippine Sea slab beneath the region from Ise Bay to western Shikoku, southwest Japan (in Japanese with English abstract), J. Seismol. Soc. Jpn., 2(57), 139-152.
    • (2004) J. Seismol. Soc. Jpn. , vol.2 , Issue.57 , pp. 139-152
    • Miyoshi, T.1    Ishibashi, K.2
  • 26
    • 0037205006 scopus 로고    scopus 로고
    • Nonvolcanic deep tremor associated with subduction in southwest Japan
    • doi:10.1126/science. 1070378
    • Obara, K. (2002), Nonvolcanic deep tremor associated with subduction in southwest Japan, Science, 296, 1679-1681, doi:10.1126/science. 1070378.
    • (2002) Science , vol.296 , pp. 1679-1681
    • Obara, K.1
  • 27
    • 33645309042 scopus 로고    scopus 로고
    • Non-volcanic deep low-frequency tremors accompanying slow slips in the southwest Japan subduction zone
    • doi:10.1016/j.tecto.2005.04.013
    • Obara, K., and H. Hirose (2006), Non-volcanic deep low-frequency tremors accompanying slow slips in the southwest Japan subduction zone, Tectonophysics, 417, 33-51, doi:10.1016/j.tecto.2005.04.013.
    • (2006) Tectonophysics , vol.417 , pp. 33-51
    • Obara, K.1    Hirose, H.2
  • 28
    • 21844454484 scopus 로고    scopus 로고
    • Very low frequency earthquakes excited by the 2004 off Kii peninsula earthquakes: A dynamic deformation process in the large accretionary prism
    • Obara, K., and Y. Ito (2005), Very low frequency earthquakes excited by the 2004 off the Kii peninsula earthquakes: A dynamic deformation process in the large accretionary prism, Earth Planets Space, 57, 321-326. (Pubitemid 40959318)
    • (2005) Earth, Planets and Space , vol.57 , Issue.4 , pp. 321-326
    • Obara, K.1    Ito, Y.2
  • 29
    • 70549112138 scopus 로고    scopus 로고
    • Characteristic activity and migration of episodic tremor and slow-slip events in central Japan
    • Obara, K., and S. Sekine (2009), Characteristic activity and migration of episodic tremor and slow-slip events in central Japan, Earth Planets Space, 61(7), 853-862.
    • (2009) Earth Planets Space , vol.61 , Issue.7 , pp. 853-862
    • Obara, K.1    Sekine, S.2
  • 30
    • 16644376328 scopus 로고    scopus 로고
    • Episodic slow slip events accompanied by non-volcanic tremors in southwest Japan subduction zone
    • doi:10.1029/2004GL020848
    • Obara, K., H. Hirose, F. Yamamizu, and K. Kasahara (2004), Episodic slow slip events accompanied by non-volcanic tremors in southwest Japan subduction zone, Geophys. Res. Lett., 31, L23602, doi:10.1029/2004GL020848.
    • (2004) Geophys. Res. Lett. , vol.31
    • Obara, K.1    Hirose, H.2    Yamamizu, F.3    Kasahara, K.4
  • 31
    • 13744260694 scopus 로고    scopus 로고
    • A densely distributed high-sensitivity seismograph network in Japan: Hi-net by National Research Institute for Earth Science and Disaster Prevention
    • DOI 10.1063/1.1854197, 021301
    • Obara, K., K. Kasahara, S. Hori, and Y. Okada (2005), A densely distributed high-sensitivity seismograph network in Japan: Hi-net by National Research Institute for Earth Science and Disaster Prevention, Rev. Sci. Instrum., 76, 021301, doi:10.1063/1.1854197. (Pubitemid 40238171)
    • (2005) Review of Scientific Instruments , vol.76 , Issue.2 , pp. 213011-2130112
    • Obara, K.1    Kasahara, K.2    Hori, S.3    Okada, Y.4
  • 33
    • 0019677497 scopus 로고
    • A negative search for an ultra-slow component to the source of the Yunnan earthquakes of May 29, 1976
    • doi:10.1016/0031-9201 (81)90009-90011
    • Okal, E. A., and L. M. Stewart (1981), A negative search for an ultra-slow component to the source of the Yunnan earthquakes of May 29, 1976, Phys. Earth Planet. Inter., 26, 208-216, doi:10.1016/0031-9201 (81)90009-90011
    • (1981) Phys. Earth Planet. Inter. , vol.26 , pp. 208-216
    • Okal, E.A.1    Stewart, L.M.2
  • 34
    • 0028193696 scopus 로고
    • Modified frequency-wavenumber algorithm for regional seismograms using Filon's quadrature: Modeling of Lg waves in eastern North America
    • doi:10.1111/j.1365-246X.1994.tb04680.x
    • Saikia, C. K. (1994), Modified frequency-wavenumber algorithm for regional seismograms using Filon's quadrature: Modeling of Lg waves in eastern North America, Geophys. J. Int., 118, 142-158, doi:10.1111/j.1365-246X.1994. tb04680.x.
    • (1994) Geophys. J. Int. , vol.118 , pp. 142-158
    • Saikia, C.K.1
  • 35
    • 36448940156 scopus 로고    scopus 로고
    • Slow slip events and seismic tremor at circum-pacific subduction zones
    • DOI 10.1029/2006RG000208
    • Schwartz, S., and J. Rokosky (2007), Slow slip events and seismic tremor at circum-pacific subduction zones, Rev. Geophys., 45, RG3004, doi:10.1029/2006RG000208. (Pubitemid 350168236)
    • (2007) Reviews of Geophysics , vol.45 , Issue.3
    • Schwartz, S.Y.1    Rokosky, J.M.2
  • 36
    • 0027836424 scopus 로고
    • A model for the motion of the Philippine Sea plate consistent with NUVEL-1 and geological data
    • doi:10.1029/93JB00782
    • Seno, T., S. Stein, and A. E. Gripp (1993), A model for the motion of the Philippine Sea plate consistent with NUVEL-1 and geological data, J. Geophys. Res., 98(B10), 17,941-17,948, doi:10.1029/93JB00782.
    • (1993) J. Geophys. Res. , vol.98 , Issue.B10
    • Seno, T.1    Stein, S.2    Gripp, A.E.3
  • 37
    • 33746111182 scopus 로고    scopus 로고
    • Low-frequency earthquakes in Shikoku, Japan, and their relationship to episodic tremor and slip
    • doi:10.1038/nature04931
    • Shelly, D. R., G. C. Beroza, S. Ide, and S. Nakamura (2006), Low-frequency earthquakes in Shikoku, Japan, and their relationship to episodic tremor and slip, Nature, 442, 188-191, doi:10.1038/nature04931.
    • (2006) Nature , vol.442 , pp. 188-191
    • Shelly, D.R.1    Beroza, G.C.2    Ide, S.3    Nakamura, S.4
  • 38
    • 33947235171 scopus 로고    scopus 로고
    • Non-volcanic tremor and low-frequency earthquake swarms
    • doi:10.1038/ nature05666
    • Shelly, D. R., G. C. Beroza, and S. Ide (2007), Non-volcanic tremor and low-frequency earthquake swarms, Nature, 446, 305-307, doi:10.1038/ nature05666.
    • (2007) Nature , vol.446 , pp. 305-307
    • Shelly, D.R.1    Beroza, G.C.2    Ide, S.3
  • 39
    • 43449116400 scopus 로고    scopus 로고
    • Simple relationship between seismic activity along Philippine Sea slab and geometry of oceanic Moho beneath southwest Japan
    • doi:10.1111/j.1365-246X.2008.03786.x
    • Shiomi, K., M. Matsubara, Y. Ito, and K. Obara (2008), Simple relationship between seismic activity along Philippine Sea slab and geometry of oceanic Moho beneath southwest Japan, Geophys. J. Int., 173, 1018-1029, doi:10.1111/j.1365-246X.2008.03786.x.
    • (2008) Geophys. J. Int. , vol.173 , pp. 1018-1029
    • Shiomi, K.1    Matsubara, M.2    Ito, Y.3    Obara, K.4
  • 40
    • 0036507541 scopus 로고    scopus 로고
    • Feasibility of real-time broadband waveform inversion for simultaneous moment tensor and centroid location determination
    • DOI 10.1785/0120000294
    • Tajima, F., C. Megnin, D. S. Dreger, and B. Romanowicz (2002), Feasibility of real-time broadband waveform inversion for simultaneous moment tensor and centroid location determination, Bull. Seismol. Soc. Am., 92, 739-750, doi:10.1785/0120000294. (Pubitemid 34617141)
    • (2002) Bulletin of the Seismological Society of America , vol.92 , Issue.2 , pp. 739-750
    • Tajima, F.1    Megnin, C.2    Dreger, D.S.3    Romanowicz, B.4
  • 41
    • 18844465854 scopus 로고
    • How good are our best models? Jackknifing, bootstrapping, and earthquake depth
    • doi:10.1029/89EO00156
    • Tichelaar, B. W., and L. J. Ruff (1989), How good are our best models? Jackknifing, bootstrapping, and earthquake depth, Eos Trans. AGU, 70(20), 593, doi:10.1029/89EO00156.
    • (1989) Eos Trans. AGU , vol.70 , Issue.20 , pp. 593
    • Tichelaar, B.W.1    Ruff, L.J.2
  • 42
    • 0002173390 scopus 로고
    • Hypocenter determination method of the Kanto-Tokai observational network for microearthquakes
    • in Japanese with English abstract, Natl. Res. Inst. for Earth Sci. and Disaster Prevent, Tsukuba, Japan
    • Ukawa, M., M. Ishida, S. Matsumura, and K. Kasahara (1984), Hypocenter determination method of the Kanto-Tokai observational network for microearthquakes (in Japanese with English abstract), Res. Note 53, 88 pp., Natl. Res. Inst. for Earth Sci. and Disaster Prevent, Tsukuba, Japan.
    • (1984) Res. Note 53
    • Ukawa, M.1    Ishida, M.2    Matsumura, S.3    Kasahara, K.4
  • 43
    • 34250722735 scopus 로고    scopus 로고
    • Scaling relationship between the duration and the amplitude of non-volcanic deep low-frequency tremors
    • DOI 10.1029/2007GL029391
    • Watanabe, T., Y. Hiramatsu, and K. Obara (2007), Scaling relationship between the duration and the amplitude of non-volcanic deep low-frequency tremors, Geophys. Res. Lett., 34, L07305, doi:10.1029/2007GL029391. (Pubitemid 46957868)
    • (2007) Geophysical Research Letters , vol.34 , Issue.7
    • Watanabe, T.1    Hiramatsu, Y.2    Obara, K.3
  • 44
    • 0000456913 scopus 로고    scopus 로고
    • New, improved version of the generic mapping tools released
    • doi:10.1029/98EO00426
    • Wessel, P., and W. H. F. Smith (1998), New, improved version of the generic mapping tools released, Eos Trans. AGU, 79, 579, doi:10.1029/98EO00426.
    • (1998) Eos Trans. AGU , vol.79 , pp. 579
    • Wessel, P.1    Smith, W.H.F.2


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.