메뉴 건너뛰기




Volumn 194, Issue 2, 2008, Pages 623-635

Hydrodynamical and radiative transfer modeling of meteoroid impacts into Saturn's rings

Author keywords

Impact processes; Planetary rings; Radiative transfer; Saturn

Indexed keywords


EID: 40849118250     PISSN: 00191035     EISSN: 10902643     Source Type: Journal    
DOI: 10.1016/j.icarus.2007.11.017     Document Type: Article
Times cited : (11)

References (77)
  • 1
    • 40849084596 scopus 로고    scopus 로고
    • Impact flash spectroscopy as a means to characterize asteroid surface composition
    • Abstract 1796
    • Adams M.A., Schultz P.H., Sugita S., and Goguen J.D. Impact flash spectroscopy as a means to characterize asteroid surface composition. Lunar Planet. Sci. XXVIII (1997) Abstract 1796
    • (1997) Lunar Planet. Sci. , vol.XXVIII
    • Adams, M.A.1    Schultz, P.H.2    Sugita, S.3    Goguen, J.D.4
  • 3
    • 0039009996 scopus 로고    scopus 로고
    • Luminous efficiency in hypervelocity impacts from the 1999 lunar Leonids
    • Bellot Rubio L.R., Ortiz J.L., and Sada P.V. Luminous efficiency in hypervelocity impacts from the 1999 lunar Leonids. Astrophys. J. 542 (2000) L65-L68
    • (2000) Astrophys. J. , vol.542
    • Bellot Rubio, L.R.1    Ortiz, J.L.2    Sada, P.V.3
  • 4
    • 0034541730 scopus 로고    scopus 로고
    • Observation and interpretation of meteoroid impact flashes on the Moon
    • Bellot Rubio L.R., Ortiz J.L., and Sada P.V. Observation and interpretation of meteoroid impact flashes on the Moon. Earth Moon Planets 82-83 (2000) 575-598
    • (2000) Earth Moon Planets , vol.82-83 , pp. 575-598
    • Bellot Rubio, L.R.1    Ortiz, J.L.2    Sada, P.V.3
  • 5
    • 0002784257 scopus 로고
    • Unsolved problems in planetary ring dynamics
    • Greenberg R., and Brahic A. (Eds), Univ. of Arizona Press, Tucson
    • Borderies N., Goldreich P., and Tremaine S. Unsolved problems in planetary ring dynamics. In: Greenberg R., and Brahic A. (Eds). Planetary Rings (1984), Univ. of Arizona Press, Tucson 713-734
    • (1984) Planetary Rings , pp. 713-734
    • Borderies, N.1    Goldreich, P.2    Tremaine, S.3
  • 7
    • 0037220525 scopus 로고    scopus 로고
    • Identification of the lunar flash of 1953 with a Fresh Crater on the Moon's surface
    • Buratti B.A., and Johnson L.L. Identification of the lunar flash of 1953 with a Fresh Crater on the Moon's surface. Icarus 161 (2003) 192-197
    • (2003) Icarus , vol.161 , pp. 192-197
    • Buratti, B.A.1    Johnson, L.L.2
  • 8
    • 0030213457 scopus 로고    scopus 로고
    • Light flash and ionization from hypervelocity impacts on ice
    • Burchell M.J., Cole M.J., and Ratcliff P.R. Light flash and ionization from hypervelocity impacts on ice. Icarus 122 (1996) 359-365
    • (1996) Icarus , vol.122 , pp. 359-365
    • Burchell, M.J.1    Cole, M.J.2    Ratcliff, P.R.3
  • 9
    • 0001209932 scopus 로고
    • On the continuous absorption coefficient of the negative hydrogen ion. III
    • Chandrasekhar S., and Breen F.H. On the continuous absorption coefficient of the negative hydrogen ion. III. Astrophys. J. 104 (1946) 430-445
    • (1946) Astrophys. J. , vol.104 , pp. 430-445
    • Chandrasekhar, S.1    Breen, F.H.2
  • 10
    • 0000305841 scopus 로고
    • The disruption of planetary satellites and the creation of planetary rings
    • Colwell J.E. The disruption of planetary satellites and the creation of planetary rings. Planet. Space Sci. 42 (1994) 1139-1149
    • (1994) Planet. Space Sci. , vol.42 , pp. 1139-1149
    • Colwell, J.E.1
  • 12
    • 0033768379 scopus 로고    scopus 로고
    • Fragmentation rates of small satellites in the outer Solar System
    • Colwell J.E., Esposito L.W., and Bundy D. Fragmentation rates of small satellites in the outer Solar System. J. Geophys. Res. 105 (2000) 17589-17599
    • (2000) J. Geophys. Res. , vol.105 , pp. 17589-17599
    • Colwell, J.E.1    Esposito, L.W.2    Bundy, D.3
  • 13
    • 0021534817 scopus 로고
    • New model of Saturn's ionosphere with an influx of water from the rings
    • Connerney J.E.P., and Waite J.H. New model of Saturn's ionosphere with an influx of water from the rings. Nature 312 (1984) 136-138
    • (1984) Nature , vol.312 , pp. 136-138
    • Connerney, J.E.P.1    Waite, J.H.2
  • 14
    • 33748887978 scopus 로고    scopus 로고
    • Ground-based observations of high velocity impacts on the Moon's surface-The lunar Leonid phenomena of 1999 and 2001
    • Abstract 1329
    • Cudnick B.M., Dunham D.W., Palmer D.M., Cook A.C., Venable R.J., and Gural P.S. Ground-based observations of high velocity impacts on the Moon's surface-The lunar Leonid phenomena of 1999 and 2001. Lunar Planet. Sci. XXXIII (2002) Abstract 1329
    • (2002) Lunar Planet. Sci. , vol.XXXIII
    • Cudnick, B.M.1    Dunham, D.W.2    Palmer, D.M.3    Cook, A.C.4    Venable, R.J.5    Gural, P.S.6
  • 16
    • 0000373892 scopus 로고
    • Bombardment of planetary rings by meteoroids: General formulation and effects of Oort cloud projectiles
    • Cuzzi J.N., and Durisen R.H. Bombardment of planetary rings by meteoroids: General formulation and effects of Oort cloud projectiles. Icarus 84 (1990) 467-501
    • (1990) Icarus , vol.84 , pp. 467-501
    • Cuzzi, J.N.1    Durisen, R.H.2
  • 17
    • 0002457920 scopus 로고    scopus 로고
    • Compositional evolution of Saturn's rings due to meteoroid bombardment
    • Cuzzi J.N., and Estrada P.R. Compositional evolution of Saturn's rings due to meteoroid bombardment. Icarus 132 (1998) 1-35
    • (1998) Icarus , vol.132 , pp. 1-35
    • Cuzzi, J.N.1    Estrada, P.R.2
  • 19
    • 0035510973 scopus 로고    scopus 로고
    • Models of the Shoemaker-Levy 9 Impacts. II. Radiative-hydrodynamic modeling of the plume splashback
    • Deming D., and Harrington J. Models of the Shoemaker-Levy 9 Impacts. II. Radiative-hydrodynamic modeling of the plume splashback. Astrophys. J. 561 (2001) 468-480
    • (2001) Astrophys. J. , vol.561 , pp. 468-480
    • Deming, D.1    Harrington, J.2
  • 20
    • 0002710766 scopus 로고
    • Radiative transfer modeling of Saturn's outer B-ring
    • Doyle L.R., Dones L., and Cuzzi J.N. Radiative transfer modeling of Saturn's outer B-ring. Icarus 80 (1989) 104-135
    • (1989) Icarus , vol.80 , pp. 104-135
    • Doyle, L.R.1    Dones, L.2    Cuzzi, J.N.3
  • 22
    • 0002285656 scopus 로고
    • Transport effects due to particle erosion mechanisms
    • Greenberg R., and Brahic A. (Eds), Univ. of Arizona Press, Tucson
    • Durisen R.H. Transport effects due to particle erosion mechanisms. In: Greenberg R., and Brahic A. (Eds). Planetary Rings (1984), Univ. of Arizona Press, Tucson 416-446
    • (1984) Planetary Rings , pp. 416-446
    • Durisen, R.H.1
  • 23
    • 0000697323 scopus 로고
    • Ballistic transport in planetary ring systems due to particle erosion mechanisms. II. Theoretical models for Saturn's A- and B-ring inner edges
    • Durisen R.H., Bode P.W., Cuzzi J.N., Cederbloom S.E., and Murphy B.W. Ballistic transport in planetary ring systems due to particle erosion mechanisms. II. Theoretical models for Saturn's A- and B-ring inner edges. Icarus 100 (1992) 364-393
    • (1992) Icarus , vol.100 , pp. 364-393
    • Durisen, R.H.1    Bode, P.W.2    Cuzzi, J.N.3    Cederbloom, S.E.4    Murphy, B.W.5
  • 24
    • 0001273155 scopus 로고
    • Measurements of the light flash produced by high velocity particle impact
    • Eichhorn G. Measurements of the light flash produced by high velocity particle impact. Planet. Space Sci. 23 (1975) 1519-1525
    • (1975) Planet. Space Sci. , vol.23 , pp. 1519-1525
    • Eichhorn, G.1
  • 25
    • 0000202063 scopus 로고
    • Analysis of the hypervelocity impact process from impact flash measurements
    • Eichhorn G. Analysis of the hypervelocity impact process from impact flash measurements. Planet. Space Sci. 24 (1976) 771-781
    • (1976) Planet. Space Sci. , vol.24 , pp. 771-781
    • Eichhorn, G.1
  • 26
    • 0001006620 scopus 로고
    • Saturn's rings-3-mm low-inclination observations and derived properties
    • Epstein E.E., Janssen M.A., and Cuzzi J.N. Saturn's rings-3-mm low-inclination observations and derived properties. Icarus 58 (1984) 403-411
    • (1984) Icarus , vol.58 , pp. 403-411
    • Epstein, E.E.1    Janssen, M.A.2    Cuzzi, J.N.3
  • 28
    • 28344449829 scopus 로고    scopus 로고
    • Spoke formation under moving plasma clouds
    • Farmer A.J., and Goldreich P. Spoke formation under moving plasma clouds. Icarus 179 (2005) 535-538
    • (2005) Icarus , vol.179 , pp. 535-538
    • Farmer, A.J.1    Goldreich, P.2
  • 29
    • 0000364226 scopus 로고    scopus 로고
    • Saturn's rings. II. Particle sizes inferred from stellar occultation data
    • French R.G., and Nicholson P.D. Saturn's rings. II. Particle sizes inferred from stellar occultation data. Icarus 145 (2000) 502-523
    • (2000) Icarus , vol.145 , pp. 502-523
    • French, R.G.1    Nicholson, P.D.2
  • 30
    • 0000437118 scopus 로고
    • A model for the formation of spokes in Saturn's ring
    • Goertz C.K., and Morfill G.E. A model for the formation of spokes in Saturn's ring. Icarus 53 (1983) 219-229
    • (1983) Icarus , vol.53 , pp. 219-229
    • Goertz, C.K.1    Morfill, G.E.2
  • 32
    • 0000371162 scopus 로고
    • What are comets made of? A model based on interstellar dust
    • Wilkening L.L. (Ed), Univ. of Arizona Press, Tucson
    • Greenberg J.M. What are comets made of? A model based on interstellar dust. In: Wilkening L.L. (Ed). Comets (1982), Univ. of Arizona Press, Tucson 131-163
    • (1982) Comets , pp. 131-163
    • Greenberg, J.M.1
  • 33
    • 0001404025 scopus 로고
    • Dust-magnetosphere interactions
    • Greenberg R., and Brahic A. (Eds), Univ. of Arizona Press, Tucson
    • Grün E., Morfill G.E., and Mendis D.A. Dust-magnetosphere interactions. In: Greenberg R., and Brahic A. (Eds). Planetary Rings (1984), Univ. of Arizona Press, Tucson 275-332
    • (1984) Planetary Rings , pp. 275-332
    • Grün, E.1    Morfill, G.E.2    Mendis, D.A.3
  • 34
    • 3943050472 scopus 로고
    • Collisional balance of the meteoritic complex
    • Grün E., Zook H.A., Fechtig H., and Giese R.H. Collisional balance of the meteoritic complex. Icarus 62 (1985) 244-272
    • (1985) Icarus , vol.62 , pp. 244-272
    • Grün, E.1    Zook, H.A.2    Fechtig, H.3    Giese, R.H.4
  • 36
    • 40849103469 scopus 로고    scopus 로고
    • Gurnett, D., Kurth, W., Hospodarsky, G., Persoon, A., Cuzzi, J.N., 2004. Evidence of meteoroid impacts on the rings from Cassini plasma wave measurements. In: American Geophysical Union Fall Meeting. Abstract P51C-06
    • Gurnett, D., Kurth, W., Hospodarsky, G., Persoon, A., Cuzzi, J.N., 2004. Evidence of meteoroid impacts on the rings from Cassini plasma wave measurements. In: American Geophysical Union Fall Meeting. Abstract P51C-06
  • 37
    • 0001744607 scopus 로고
    • Results of Pioneer 10 and 11 meteoroid experiments: Interplanetary and near Saturn
    • Humes D.H. Results of Pioneer 10 and 11 meteoroid experiments: Interplanetary and near Saturn. J. Geophys. Res. 85 (1980) 5841-5852
    • (1980) J. Geophys. Res. , vol.85 , pp. 5841-5852
    • Humes, D.H.1
  • 38
    • 0011463341 scopus 로고
    • Ring torque of Saturn from interplanetary meteoroid impact
    • Ip W.-H. Ring torque of Saturn from interplanetary meteoroid impact. Icarus 60 (1984) 547-552
    • (1984) Icarus , vol.60 , pp. 547-552
    • Ip, W.-H.1
  • 39
    • 3342998048 scopus 로고
    • Polynomial partition function approximations of 344 atomic and molecular species
    • Irwin A.W. Polynomial partition function approximations of 344 atomic and molecular species. Astrophys. J. Suppl. 45 (1981) 621-633
    • (1981) Astrophys. J. Suppl. , vol.45 , pp. 621-633
    • Irwin, A.W.1
  • 40
    • 0000307145 scopus 로고    scopus 로고
    • Observation of expanding vapor cloud generated by hypervelocity impact
    • Kadono T., and Fujiwara A. Observation of expanding vapor cloud generated by hypervelocity impact. J. Geophys. Res. 101 (1996) 26097-26109
    • (1996) J. Geophys. Res. , vol.101 , pp. 26097-26109
    • Kadono, T.1    Fujiwara, A.2
  • 41
    • 0001571959 scopus 로고
    • Electron radiative transitions in a Coulomb field
    • Karzas W.J., and Latter R. Electron radiative transitions in a Coulomb field. Astrophys. J. Suppl. 6 (1961) 167-212
    • (1961) Astrophys. J. Suppl. , vol.6 , pp. 167-212
    • Karzas, W.J.1    Latter, R.2
  • 42
    • 6144277989 scopus 로고
    • A preliminary theoretical line-blanketed model solar photosphere
    • Kurucz R.L. A preliminary theoretical line-blanketed model solar photosphere. Solar Phys. 34 (1974) 17-23
    • (1974) Solar Phys. , vol.34 , pp. 17-23
    • Kurucz, R.L.1
  • 43
    • 41549113251 scopus 로고    scopus 로고
    • Penetration of the heliosphere by the interstellar dust stream during solar maximum
    • 10.1029/2003JA009872
    • Landgraf M., Krüger H., Altobelli N., and Grün E. Penetration of the heliosphere by the interstellar dust stream during solar maximum. J. Geophys. Res. 108 (2003) 10.1029/2003JA009872
    • (2003) J. Geophys. Res. , vol.108
    • Landgraf, M.1    Krüger, H.2    Altobelli, N.3    Grün, E.4
  • 45
    • 0027876823 scopus 로고
    • A direct measurement of the terrestrial mass accretion rate of cosmic dust
    • Love S.G., and Brownlee D.E. A direct measurement of the terrestrial mass accretion rate of cosmic dust. Science 262 (1995) 550-553
    • (1995) Science , vol.262 , pp. 550-553
    • Love, S.G.1    Brownlee, D.E.2
  • 50
    • 40849093577 scopus 로고    scopus 로고
    • Mitchell, C.J., Porco, C.C., 2006. New spokes observed in Saturn's B ring. In: American Geophysical Union Fall Meeting. Abstract P23E-0107
    • Mitchell, C.J., Porco, C.C., 2006. New spokes observed in Saturn's B ring. In: American Geophysical Union Fall Meeting. Abstract P23E-0107
  • 52
    • 0004888046 scopus 로고
    • Plasma clouds in Saturn's rings
    • Morfill G.E., and Goertz C.K. Plasma clouds in Saturn's rings. Icarus 55 (1983) 111-123
    • (1983) Icarus , vol.55 , pp. 111-123
    • Morfill, G.E.1    Goertz, C.K.2
  • 53
    • 28344436281 scopus 로고    scopus 로고
    • Spoke formation under moving plasma clouds-The Goertz-Morfill model revisited
    • Morfill G.E., and Thomas H.M. Spoke formation under moving plasma clouds-The Goertz-Morfill model revisited. Icarus 179 (2005) 539-542
    • (2005) Icarus , vol.179 , pp. 539-542
    • Morfill, G.E.1    Thomas, H.M.2
  • 54
    • 0001171243 scopus 로고
    • Some consequences of meteoroid impacts on Saturn's rings
    • Morfill G.E., Fechtig H., Grün E., and Goertz C.K. Some consequences of meteoroid impacts on Saturn's rings. Icarus 55 (1983) 439-447
    • (1983) Icarus , vol.55 , pp. 439-447
    • Morfill, G.E.1    Fechtig, H.2    Grün, E.3    Goertz, C.K.4
  • 56
    • 0000064106 scopus 로고
    • A micrometeorite erosion model and the age of Saturn's rings
    • Northrop T.G., and Connerney J.E.P. A micrometeorite erosion model and the age of Saturn's rings. Icarus 70 (1987) 124-137
    • (1987) Icarus , vol.70 , pp. 124-137
    • Northrop, T.G.1    Connerney, J.E.P.2
  • 57
    • 0000203774 scopus 로고
    • Stability of negatively charged dust grains in Saturn's ring plane
    • Northrop T.G., and Hill J.R. Stability of negatively charged dust grains in Saturn's ring plane. J. Geophys. Res. 87 (1982) 6045-6051
    • (1982) J. Geophys. Res. , vol.87 , pp. 6045-6051
    • Northrop, T.G.1    Hill, J.R.2
  • 58
    • 0036080931 scopus 로고    scopus 로고
    • Cometary delivery of biogenic elements to Europa
    • Pierazzo E., and Chyba C. Cometary delivery of biogenic elements to Europa. Icarus 157 (2002) 120-127
    • (2002) Icarus , vol.157 , pp. 120-127
    • Pierazzo, E.1    Chyba, C.2
  • 59
    • 0031161460 scopus 로고    scopus 로고
    • A reevaluation of impact melt production
    • Pierazzo E., Vickery A.M., and Melosh H.J. A reevaluation of impact melt production. Icarus 127 (1997) 408-423
    • (1997) Icarus , vol.127 , pp. 408-423
    • Pierazzo, E.1    Vickery, A.M.2    Melosh, H.J.3
  • 60
    • 4244107344 scopus 로고
    • The periodic variation of spokes in Saturn's rings
    • Porco C.C., and Danielson G.E. The periodic variation of spokes in Saturn's rings. Astron. J. 87 (1982) 826-833
    • (1982) Astron. J. , vol.87 , pp. 826-833
    • Porco, C.C.1    Danielson, G.E.2
  • 62
    • 0012859187 scopus 로고    scopus 로고
    • Dynamical evolution of the Prometheus-Pandora system
    • Poulet F., and Sicardy B. Dynamical evolution of the Prometheus-Pandora system. Mon. Not. R. Astron. Soc. 322 (2001) 343-355
    • (2001) Mon. Not. R. Astron. Soc. , vol.322 , pp. 343-355
    • Poulet, F.1    Sicardy, B.2
  • 64
    • 0030424053 scopus 로고    scopus 로고
    • Effect of impact angle on vaporization
    • Schultz P.H. Effect of impact angle on vaporization. J. Geophys. Res. 101 (1996) 21117-21136
    • (1996) J. Geophys. Res. , vol.101 , pp. 21117-21136
    • Schultz, P.H.1
  • 66
    • 0032491602 scopus 로고    scopus 로고
    • Detection of centimeter-sized meteoroid impact events in Saturn's F ring
    • Showalter M.R. Detection of centimeter-sized meteoroid impact events in Saturn's F ring. Science 282 (1998) 1099-1102
    • (1998) Science , vol.282 , pp. 1099-1102
    • Showalter, M.R.1
  • 68
    • 0033604793 scopus 로고    scopus 로고
    • Spectroscopic characterization of hypervelocity jetting: Comparison with a standard theory
    • Sugita S., and Schultz P.H. Spectroscopic characterization of hypervelocity jetting: Comparison with a standard theory. J. Geophys. Res. 104 (1999) 30825-30845
    • (1999) J. Geophys. Res. , vol.104 , pp. 30825-30845
    • Sugita, S.1    Schultz, P.H.2
  • 69
    • 0141857715 scopus 로고    scopus 로고
    • Interactions between impact-induced vapor clouds and the ambient atmosphere. 1. Spectroscopic observations using diatomic molecular emission
    • 10.1029/2002JE001959 5051
    • Sugita S., and Schultz P.H. Interactions between impact-induced vapor clouds and the ambient atmosphere. 1. Spectroscopic observations using diatomic molecular emission. J. Geophys. Res. 108 (2003) 10.1029/2002JE001959 5051
    • (2003) J. Geophys. Res. , vol.108
    • Sugita, S.1    Schultz, P.H.2
  • 70
    • 0032566387 scopus 로고    scopus 로고
    • Spectroscopic measurements of vapor clouds due to oblique impacts
    • Sugita S., Schultz P.H., and Adams M.A. Spectroscopic measurements of vapor clouds due to oblique impacts. J. Geophys. Res. 103 (1998) 19427-19441
    • (1998) J. Geophys. Res. , vol.103 , pp. 19427-19441
    • Sugita, S.1    Schultz, P.H.2    Adams, M.A.3
  • 71
    • 1542289015 scopus 로고    scopus 로고
    • Intensities of atomic lines and molecular bands observed in impact-induced luminescence
    • 10.1029/2003JE002156 5140
    • Sugita S., Schultz P.H., and Hasegawa S. Intensities of atomic lines and molecular bands observed in impact-induced luminescence. J. Geophys. Res. 108 (2003) 10.1029/2003JE002156 5140
    • (2003) J. Geophys. Res. , vol.108
    • Sugita, S.1    Schultz, P.H.2    Hasegawa, S.3
  • 72
    • 0012492211 scopus 로고
    • On the nature of the spokes in Saturn's rings
    • Tagger M., Henriksen R.N., and Pellat R. On the nature of the spokes in Saturn's rings. Icarus 91 (1991) 297-314
    • (1991) Icarus , vol.91 , pp. 297-314
    • Tagger, M.1    Henriksen, R.N.2    Pellat, R.3
  • 73
    • 40849103467 scopus 로고    scopus 로고
    • Thompson, S.L., Lauson, H.S., 1972. Improvements in the chart-D radiation-hydrodynamic code. III. Revised analytical equation of state. Report SC-RR-710714, Sandia National Laboratories, Albuquerque, NM
    • Thompson, S.L., Lauson, H.S., 1972. Improvements in the chart-D radiation-hydrodynamic code. III. Revised analytical equation of state. Report SC-RR-710714, Sandia National Laboratories, Albuquerque, NM
  • 75
    • 0036752081 scopus 로고    scopus 로고
    • Lightcurves of 1999 Leonid impact flashes on the Moon
    • Yanagisawa M., and Kisaichi N. Lightcurves of 1999 Leonid impact flashes on the Moon. Icarus 159 (2002) 31-38
    • (2002) Icarus , vol.159 , pp. 31-38
    • Yanagisawa, M.1    Kisaichi, N.2
  • 76
    • 0000890516 scopus 로고
    • Saturn's rings: Particle size distributions for thin layer models
    • Zebker H.A., Marouf E.A., and Tyler G.L. Saturn's rings: Particle size distributions for thin layer models. Icarus 64 (1985) 531-548
    • (1985) Icarus , vol.64 , pp. 531-548
    • Zebker, H.A.1    Marouf, E.A.2    Tyler, G.L.3
  • 77
    • 0342309754 scopus 로고
    • A finite difference scheme for time-dependent spherical radiation hydrodynamics problems
    • Zinn J. A finite difference scheme for time-dependent spherical radiation hydrodynamics problems. J. Comput. Phys. 13 (1973) 569-590
    • (1973) J. Comput. Phys. , vol.13 , pp. 569-590
    • Zinn, J.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.