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Your search keyword '"Noh, S.‐J."' showing total 149 results
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149 results on '"Noh, S.‐J."'

1. Spin-orbit torque-driven magnetization switching and thermal effects studied in Ta\CoFeB\MgO nanowires

Author

Conte, R. Lo, Hrabec, A., Mihai, A. P., Schulz, T., Noh, S. -J., Marrows, C. H., Moore, T. A., and Kläui, M.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We demonstrate magnetization switching in out-of-plane magnetized Ta\CoFeB\MgO nanowires by current pulse injection along the nanowires, both with and without a constant and uniform magnetic field collinear to the current direction. We deduce that an effective torque arising from spin-orbit effects in the multilayer drives the switching mechanism. While the generation of a component of the magnetization along the current direction is crucial for the switching to occur, we observe that even without a longitudinal field thermally generated magnetization fluctuations can lead to switching. Analysis using a generalized N\'eel-Brown model enables key parameters of the thermally induced spin-orbit torques switching process to be estimated, such as the attempt frequency and the effective energy barrier., Comment: 8 pages, 3 figures

Published
2014
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22. Advancing Data Assimilation in Operational Hydrologic Forecasting: Progresses, Challenges, and Emerging Opportunities

Author

Liu, Yuqiong, Weerts, A, Clark, M, Hendricks Franssen, H.-J, Kumar, S, Moradkhani, H, Seo, D.-J, Schwanenberg, D, Smith, P, van Dijk, A. I. J. M, van Velzen, N, He, M, Lee, H, Noh, S. J, Rakovec, O, and Restrepo, P

Subjects
Earth Resources And Remote Sensing, Meteorology And Climatology
Abstract

Data assimilation (DA) holds considerable potential for improving hydrologic predictions as demonstrated in numerous research studies. However, advances in hydrologic DA research have not been adequately or timely implemented in operational forecast systems to improve the skill of forecasts for better informed real-world decision making. This is due in part to a lack of mechanisms to properly quantify the uncertainty in observations and forecast models in real-time forecasting situations and to conduct the merging of data and models in a way that is adequately efficient and transparent to operational forecasters. The need for effective DA of useful hydrologic data into the forecast process has become increasingly recognized in recent years. This motivated a hydrologic DA workshop in Delft, the Netherlands in November 2010, which focused on advancing DA in operational hydrologic forecasting and water resources management. As an outcome of the workshop, this paper reviews, in relevant detail, the current status of DA applications in both hydrologic research and operational practices, and discusses the existing or potential hurdles and challenges in transitioning hydrologic DA research into cost-effective operational forecasting tools, as well as the potential pathways and newly emerging opportunities for overcoming these challenges. Several related aspects are discussed, including (1) theoretical or mathematical aspects in DA algorithms, (2) the estimation of different types of uncertainty, (3) new observations and their objective use in hydrologic DA, (4) the use of DA for real-time control of water resources systems, and (5) the development of community-based, generic DA tools for hydrologic applications. It is recommended that cost-effective transition of hydrologic DA from research to operations should be helped by developing community-based, generic modeling and DA tools or frameworks, and through fostering collaborative efforts among hydrologic modellers, DA developers, and operational forecasters.

Published
2012
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26. Low-energy D+ and H+ ion irradiation effects on highly oriented pyrolytic graphite.

Author

Kue Park, Jun, Won Lee, Kyu, Hee Han, Jun, Jung Kweon, Jin, Kim, Dowan, Eui Lee, Cheol, Lim, Sun-Taek, Kim, Gon-Ho, Noh, S. J., and Kim, H. S.

Subjects
IRRADIATION, RAMAN spectroscopy, PYROLYTIC graphite, PHOTOELECTRON spectroscopy, PHOTOEMISSION
Abstract

We have investigated the low-energy (100 eV) D+ and H+ ion irradiation effects on the structural and chemical properties of highly oriented pyrolytic graphite (HOPG). Structural disorder due to the ion irradiation was identified by the Raman spectroscopy, the D+ irradiation giving rise to greater structural disorder than the H+ irradiation. Only sp2 bonding was identified in the X-ray photoemission spectroscopy of the D+-irradiated HOPG, indicating no change in the surface chemical structure. The H+ irradiation, on the other hand, gave rise to sp3 bonding and π-π* transition, the sp3 bonding increasing with increasing irradiation dose. It is thus shown that the chemical properties of the HOPG surface may be sensitively modified by the low-energy H+ ion irradiation, but not by the low-energy D+ ion irradiation. [ABSTRACT FROM AUTHOR]

Published
2013
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27. Influence of interface state in Fe/MgO/Fe magnetic tunnel junction system: C modified interfaces-a first principle study.

Author

Wang, T. X., Li, Y., Lee, K. J., Cho, J. U., Kim, D. K., Noh, S. J., and Kim, Y. K.

Subjects
MAGNETIC tunnelling, MINING engineering, DENSITY functionals, ELECTRIC admittance, MAGNETIC reluctance
Abstract

The Fe/MgO/Fe magnetic tunnel junction with C modified interfaces has been studied based on the first principle density function theory method under a finite bias voltage for thin (five layers) and thick (ten layers) MgO barriers. Positive and negative tunneling magnetic resistance (TMR) ratios are obtained as a function of the interface structure. We found that the tunneling conductance is highly nonlinear for asymmetric systems with C at one side of the barrier, and even a sign reversal of the TMR as a function of the bias was found to be in agreement with experiments. [ABSTRACT FROM AUTHOR]

Published
2011
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32. Electric dipole moment in KH2PO4 systematically modified by proton irradiation.

Author

Jung Kweon, Jin, Eui Lee, Cheol, Noh, S. J., and Kim, H. S.

Subjects
DIELECTRICS, DIPOLE moments, ELECTROCHEMICAL analysis, IMPEDANCE spectroscopy, MAGNETIC dipoles
Abstract

We have carried out an impedance spectroscopy study on a series of proton-irradiated KH2PO4 (KDP) systems. A systematic modification was observed in the transverse dipole moment of the proton-irradiated KDP systems, associated with hydrogen-ion displacements, as obtained from dielectric constant measurements by using a mean-field approximation. Besides, intercorrelation of the charge transport with the dielectric properties was revealed, both having closely to do with the hydrogen-bond modification. [ABSTRACT FROM AUTHOR]

Published
2012
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36. Plasma-Wall Interaction Facilities in Korea

Author

Chung, K.-S., primary, Woo, H.-J., additional, Cho, S.-G., additional, Choi, Y.-S., additional, Han, S.-H., additional, Hong, B.-G., additional, Hong, S.-H., additional, Kim, H.-S., additional, Noh, S.-J., additional, Lho, T., additional, Park, S.-J., additional, and You, H.-J., additional

Published
2013
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37. Advancing data assimilation in operational hydrologic forecasting: progresses, challenges, and emerging opportunities

Author

Liu, Y., primary, Weerts, A. H., additional, Clark, M., additional, Hendricks Franssen, H.-J., additional, Kumar, S., additional, Moradkhani, H., additional, Seo, D.-J., additional, Schwanenberg, D., additional, Smith, P., additional, van Dijk, A. I. J. M., additional, van Velzen, N., additional, He, M., additional, Lee, H., additional, Noh, S. J., additional, Rakovec, O., additional, and Restrepo, P., additional

Published
2012
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40. Effect of hot anisotropic He+ions on the growth and damping of electromagnetic ion cyclotron waves in the inner magnetosphere

Author

Lee, D.‐Y., Noh, S.‐J., Choi, C.‐R., Lee, J. J., and Hwang, J. A.

Abstract

Physics of electromagnetic ion cyclotron (EMIC) waves is complicated by inclusion of heavy ions. In particular, He+ions in the magnetosphere have long been considered to play important roles. Motivated by recent observations, we examine the effect of the inclusion of hot anisotropic He+ions in addition to the usual hot anisotropic protons. We solve the kinetic dispersion relation for this examination and find the following results. First, inclusion of hot anisotropic He+ions leads to the growth of EMIC waves at frequencies below the He+gyrofrequency (He band) and a reduction of the EMIC wave growth rates (or damping of the waves) at frequencies between the proton and He+gyrofrequencies (H band). Second, this effect is more dramatic for higher temperatures of He+that would play a role in damping EMIC waves for both frequency bands and especially for cases without a He+temperature anisotropy. Lastly, the effect is more prominent for cold plasma dominant conditions such as the region inside the plasmasphere or plume than for hot proton dominant conditions such as the region outside the plasmasphere. We propose that this last effect can at least partially explain the satellite observations indicating the preferred (though not exclusive) occurrence of He band waves inside the plasmasphere for the times when hot anisotropic He+ions are supplied from the plasma sheet and ring current. Hot anisotropic He+ions cause increase (decrease) of He+(H+) band EMIC wave growth ratesThis effect is more significant for higher temperatures of He+It is more effective for cold plasma dominant conditions than for hot proton dominant conditions

Published
2017
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