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Search Results: 1 - 10 of 424478 matches for " S. K. Kwon "
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Unquenched large orbital magnetic moment in NiO
S. K. Kwon,B. I. Min
Physics , 2000, DOI: 10.1103/PhysRevB.62.73
Abstract: Magnetic properties of NiO are investigated by incorporating the spin-orbit interaction in the LSDA+U scheme. It is found that the large part of orbital moment remains unquenched in NiO. The orbital moment contributes about mu_L = 0.29 mu_B to the total magnetic moment of M = 1.93 mu_B, as leads to the orbital-to-spin angular momentum ratio of L/S = 0.36. The theoretical values are in good agreement with recent magnetic X-ray scattering measurements.
Origin of the giant magnetic moments of Fe impurities on and in Cs films
S. K. Kwon,B. I. Min
Physics , 1999, DOI: 10.1103/PhysRevLett.84.3970
Abstract: To explore the origin of the observed giant magnetic moments ($\sim 7 \mu_B$) of Fe impurities on the surface and in the bulk of Cs films, we have performed the relativistic LSDA + U calculations using the linearized muffin-tin orbital (LMTO) band method. We have found that Fe impurities in Cs behave differently from those in noble metals or in Pd. Whereas the induced spin polarization of Cs atoms is negligible, the Fe ion itself is found to be the source of the giant magnetic moment. The 3d electrons of Fe in Cs are localized as the 4f electrons in rare-earth ions so that the orbital magnetic moment becomes as large as the spin magnetic moment. The calculated total magnetic moment of $M = 6.43 \mu_B$, which comes mainly from Fe ion, is close to the experimentally observed value.
Charge and Orbital Ordering and Spin State Transition Driven by Structural Distortion in YBaCo_2O_5
S. K. Kwon,B. I. Min
Physics , 2000, DOI: 10.1103/PhysRevB.62.R14637
Abstract: We have investigated electronic structures of antiferromagnetic YBaCo_2O_5 using the local spin-density approximation (LSDA) + U method. The charge and orbital ordered insulating ground state is correctly obtained with the strong on-site Coulomb interaction. Co^{2+} and Co^{3+} ions are found to be in the high spin (HS) and intermediate spin (IS) state, respectively. It is considered that the tetragonal to orthorhombic structural transition is responsible for the ordering phenomena and the spin states of Co ions. The large contribution of the orbital moment to the total magnetic moment indicates that the spin-orbit coupling is also important in YBaCo_2O_5.
Absolute Position Determination with Single Vision Using Laser Range Finders
H. S. Woo,K. S. Kwon,B. G. Kim
International Journal of Machine Learning and Computing , 2013, DOI: 10.7763/ijmlc.2013.v3.291
Abstract: With the speed of information networks and the demand for real time service over the past few years, demand for up-to-date spatial information has accordingly been rising. Mobile mapping systems can be efficient equipments that meet such requirements to achieve real-time spatial information. For that, rapid absolute position determination is needed using images obtained from mobile mapping systems. A method has been proposed, which determine the absolute position of single vision in real time using sensor position, attitude information, and distances acquired from laser range finders. The proposed method provides the solution of absolute position with distances of more than 3 measuring points and angles between rays connecting the lens to the road surface. It is expected that the proposed method can perform rapid geospatial data generation from single vision by minimizing separate post-processing for absolute position determination.
Itinerant ferromagnetism in half-metallic CoS_2
S. K. Kwon,S. J. Youn,B. I. Min
Physics , 2000, DOI: 10.1103/PhysRevB.62.357
Abstract: We have investigated electronic and magnetic properties of the pyrite-type CoS_2 using the linearized muffin-tin orbital (LMTO) band method. We have obtained the ferromagnetic ground state with nearly half-metallic nature. The half-metallic stability is studied by using the fixed spin moment method. The non-negligible orbital magnetic moment of Co 3d electrons is obtained as $\mu_L = 0.06 \mu_B$ in the local spin density approximation (LSDA). The calculated ratio of the orbital to spin angular momenta /< S_z > = 0.15 is consistent with experiment. The effect of the Coulomb correlation between Co 3d electrons is also explored with the LSDA + U method. The Coulomb correlation at Co sites is not so large, $U \lesssim 1$ eV, and so CoS_2 is possibly categorized as an itinerant ferromagnet. It is found that the observed electronic and magnetic behaviors of CoS_2 can be described better by the LSDA than by the LSDA + U.
VERTICAL TEMPERATURE AND MOISTURE STRUCTURE IN LOWER ATMOSPHERE RETRIVED FROM TERRA/MODIS
Kim,Y. S; Kwon,B. H; Hong,K. M;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000200058
Abstract: two modis instruments on board the terra and aqua satellites are operational for global remote sensing of the land, ocean and atmosphere. atmospheric sounding data with a high spatial resolution from modis will provide a wealth of useful information. the vertical air temperature and moisture data were retrieved using the modis data, and compared with the radiosonde data obtained in the korean peninsula. the correlation coefficients are 0.99 and 0.89 for air temperature and moisture cases, respectively. air temperature data were relatively good agreement, but the moisture data from modis were underestimated
ESTIMATION OF THE AIR TEMPERATURE OVER THE OCEAN BASED ON SATELLITE DATA
Y. S Kim,B. H Kwon,K. M Hong
Gayana (Concepción) , 2004,
Abstract:
VERTICAL TEMPERATURE AND MOISTURE STRUCTURE IN LOWER ATMOSPHERE RETRIVED FROM TERRA/MODIS
Y. S Kim,B. H Kwon,K. M Hong
Gayana (Concepción) , 2004,
Abstract: Two MODIS instruments on board the Terra and Aqua Satellites are operational for global remote sensing of the land, ocean and atmosphere. Atmospheric sounding data with a high spatial resolution from MODIS will provide a wealth of useful information. The vertical air temperature and moisture data were retrieved using the MODIS data, and compared with the radiosonde data obtained in the Korean Peninsula. The correlation coefficients are 0.99 and 0.89 for air temperature and moisture cases, respectively. Air temperature data were relatively good agreement, but the moisture data from MODIS were underestimated
Weighted L2 inequalities for classical and semiclassical weights
H. S. Jung,K. H. Kwon,D. W. Lee
Journal of Inequalities and Applications , 1997, DOI: 10.1155/s102558349700012x
Abstract: We give weighted L2 Markov-Bemstein or Landau type inequalities for classical and semiclassical weights.
Electronic structure of metallic antiperovskite compound GaCMn$_3$
J. H. Shim,S. K. Kwon,B. I. Min
Physics , 2002, DOI: 10.1103/PhysRevB.66.020406
Abstract: We have investigated electronic structures of antiperovskite GaCMn$_3$ and related Mn compounds SnCMn$_3$, ZnCMn$_3$, and ZnNMn$_3$. In the paramagnetic state of GaCMn$_3$, the Fermi surface nesting feature along the $\Gamma{\rm R}$ direction is observed, which induces the antiferromagnetic (AFM) spin ordering with the nesting vector {\bf Q} $\sim \Gamma{\rm R}$. Calculated susceptibilities confirm the nesting scenario for GaCMn$_3$ and also explain various magnetic structures of other antiperovskite compounds. Through the band folding effect, the AFM phase of GaCMn$_3$ is stabilized. Nearly equal densities of states at the Fermi level in the ferromagnetic and AFM phases of GaCMn$_3$ indicate that two phases are competing in the ground state.
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