4,589 research outputs found

    Quantitative Analysis on the Energy and Environmental Impact of the Korean National Energy R&D Roadmap a Using Bottom-Up Energy System Model

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    According to the Paris Agreement at the 21st Conference of the Parties, 196 member states are obliged to submit their Intended Nationally Determined Contributions (INDC) for every 5 years. As a member, South Korea has already proposed the reduction target and need to submit the achievement as a result of the policies and endeavors in the near future. In this paper, a Korean bottom-up energy system model to support the low-carbon national energy R&D roadmap will be introduced and through the modeling of various scenarios, the mid-to long-term impact on energy consumptions and CO2 emissions will be analyzed as well. The results of the analysis showed that, assuming R&D investments for the 11 types of technologies, savings of 13.7% with regards to final energy consumptions compared to the baseline scenario would be feasible by 2050. Furthermore, in the field of power generation, the generation proportion of new and renewable energy is expected to increase from 3.0% as of 2011 to 19.4% by 2050. This research also suggested that the analysis on the Energy Technology R&D Roadmap based on the model can be used not only for overall impact analysis and R&D portfolio establishment, but also for the development of detailed R&D strategies.1100Ysciessciscopu

    On the Csorgo-RƩvƩsz increments of finite dimensional Gaussian random fields

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    In this paper, we establish some limit theorems on the combined Csorgo-RƩvƩsz increments with moduli of continuity for finite dimensional Gaussian random fields under mild conditions, via estimating upper bounds of large deviation probabilities on suprema of the finite dimensional Gaussian random fields.Csorgo-RƩvƩsz increment; Gaussian process; random field; modulus of continuity; quasi-increasing; regularly varying function; large deviation probability.

    Relaxation of superfluid turbulence in highly oblate Bose-Einstein condensates

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    We investigate thermal relaxation of superfluid turbulence in a highly oblate Bose-Einstein condensate. We generate turbulent flow in the condensate by sweeping the center region of the condensate with a repulsive optical potential. The turbulent condensate shows a spatially disordered distribution of quantized vortices and the vortex number of the condensate exhibits nonexponential decay behavior which we attribute to the vortex pair annihilation. The vortex-antivortex collisions in the condensate are identified with crescent-shaped, coalesced vortex cores. We observe that the nonexponential decay of the vortex number is quantitatively well described by a rate equation consisting of one-body and two-body decay terms. In our measurement, we find that the local two-body decay rate is closely proportional to T2/Ī¼T^2/\mu, where TT is the temperature and Ī¼\mu is the chemical potential.Comment: 7 pages, 9 figure

    Observation of a Geometric Hall Effect in a Spinor Bose-Einstein Condensate with a Skyrmion Spin Texture

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    For a spin-carrying particle moving in a spatially varying magnetic field, effective electromagnetic forces can arise due to the geometric phase associated with adiabatic spin rotation of the particle. We report the observation of a geometric Hall effect in a spinor Bose-Einstein condensate with a skyrmion spin texture. Under translational oscillations of the spin texture, the condensate resonantly develops a circular motion in a harmonic trap, demonstrating the existence of an effective Lorentz force. When the condensate circulates, quantized vortices are nucleated in the boundary region of the condensate and the vortex number increases over 100 without significant heating. We attribute the vortex nucleation to the shearing effect of the effective Lorentz force from the inhomogeneous effective magnetic field.Comment: 9 pages, 11 figure

    Highly transmissive subtractive color filters based on an all-dielectric metasurface incorporating TiO2 nanopillars

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    Transmissive subtractive color filters are proposed and demonstrated that take advantage of an all-dielectric metasurface based on a lattice of TiO2 nanopillars (NPs), rendering a high transmission efficiency that exceeds 90%. TiO2 NP elements have been created that exhibit a high aspect ratio. Specifically, a series of lithographic processes are conducted to form a narrow and deep hole in the photoresist, which is accompanied by atomic layer deposition of TiO2. A broad palette of vivid colors encompassing the visible band has been obtained by adjusting the NP diameter for a constant duty ratio of 0.35. For the NP resonator, the electric and magnetic field profiles in conjunction with the scattering cross-sections have been meticulously investigated to theoretically validate that the resonant transmission dips are primarily governed by the simultaneous excitation of an electric dipole and a magnetic dipole via Mie scattering.National Research Foundation of Korea (NRF), funded by the Korean government (MSIP) (No. 2016R1A2B2010170); Kwangwoon University; Australian Research Council Future Fellowship (FT110100853, Dr. Duk-Yong Choi)
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