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Chiral edge mode in the coupled dynamics of magnetic solitons in a honeycomb latticeJun 09 2017Jul 25 2017Motivated by a recent experimental demonstration of a chiral edge mode in an array of spinning gyroscopes, we theoretically study the coupled gyration modes of topological magnetic solitons, vortices and magnetic bubbles, arranged as a honeycomb lattice. ... More

Interaction Between a Domain Wall and Spin Supercurrent in Easy-cone MagnetsSep 30 2016A domain wall and spin supercurrent can coexist in magnets with easy-cone anisotropy owing to simultaneous spontaneous breaking of Z$_2$ and U(1) symmetries. Their interaction is theoretically investigated in quasi one-dimensional ferromagnets within ... More

Magnetic Domain Walls as Hosts of Spin Superfluids and Generators of SkyrmionsJan 28 2017Jun 21 2017A domain wall in a magnet with easy-axis anisotropy is shown to harbor spin superfluid associated with its spontaneous breaking of the U(1) spin-rotational symmetry. The spin superfluid is shown to have several topological properties, which are absent ... More

Easy-Plane Magnetic Strip as a Long Josephson JunctionFeb 12 2018Spin-torque-biased magnetic dynamics in an easy-plane ferromagnet (EPF) is theoretically studied in the presence of a weak in-plane anisotropy. While this anisotropy spoils U(1) symmetry thereby quenching the conventional spin superfluidity, we show that ... More

Magnetoelectric antiferromagnets as platforms for the manipulation of solitonsJul 07 2017We study the magnetic dynamics of magnetoelectric antiferromagnetic thin films, where an unconventional boundary ferromagnetism coexists with the bulk N\'{e}el phase below the N\'{e}el temperature. The spin exchange between the two order parameters yields ... More

Gauge fields and related forces in antiferromagnetic solitonsJan 18 2017We derive equations of motion for topological solitons in antiferromagnets under the combined action of perturbations such as an external magnetic field and torque-generating electrical current. Aside from conservative forces, such perturbations generate ... More

Topological spin-transfer drag driven by skyrmion diffusionMay 10 2016Jul 22 2016We study the spin-transfer drag mediated by the Brownian motion of skyrmions. The essential idea is illustrated in a two-terminal geometry, in which a thin film of a magnetic insulator is placed in between two metallic reservoirs. An electric current ... More

Mechanical Actuation of Magnetic Domain-Wall MotionJun 17 2016Nov 30 2016We theoretically study the motion of a magnetic domain wall induced by transverse elastic waves in a one-dimensional magnetic wire, which respects both rotational and translational symmetries. By invoking the conservation of the associated total angular ... More

Laser control of magnonic topological phases in antiferromagnetsJul 17 2019We study the laser control of magnon topological phases induced by the Aharonov-Casher effect in insulating antiferromagnets (AFs). Since the laser electric field can be considered as a time-periodic perturbation, we apply the Floquet theory and perform ... More

Gyrotropic elastic response of skyrmion crystals to current-induced tensionsFeb 10 2017Jul 08 2017We theoretically study the dynamics of skyrmion crystals in electrically-insulating chiral magnets subjected to current-induced spin torques by adjacent metallic layers. We develop an elasticity theory that accounts for the gyrotropic force engendered ... More

Symmetry dictated grain boundary state in a two-dimensional topological insulatorJul 04 2019Jul 05 2019Structural imperfections such as grain boundaries (GBs) and dislocations are ubiquitous in solids and have been of central importance in understanding nature of polycrystals. In addition to their classical roles, advent of topological insulators (TIs) ... More

Bidirectional spin-wave-driven domain wall motion in antiferromagnetically coupled ferrimagnetsMay 09 2019We investigate ferrimagnetic domain wall dynamics induced by circularly polarized spin waves theoretically and numerically. We find that the direction of domain wall motion depends on both the circular polarization of spin waves and the sign of net spin ... More

Magnonic topological insulators in antiferromagnetsJul 24 2017Nov 28 2017Extending the notion of symmetry protected topological phases to insulating antiferromagnets (AFs) described in terms of opposite magnetic dipole moments associated with the magnetic N$\acute{{\rm{e}}} $el order, we establish a bosonic counterpart of ... More

Topological Magnon-Phonon Hybrid Excitations in Two-Dimensional Ferromagnets with Tunable Chern NumbersJul 04 2019We theoretically investigate magnon-phonon hybrid excitations in two-dimensional ferromagnets. The bulk bands of hybrid excitations, which are referred to as magnon-polarons, are analytically shown to be topologically nontrivial, possessing finite Chern ... More

A Realization of the Haldane-Kane-Mele Model in a System of Localized SpinsMar 15 2016Sep 20 2016We theoretically study a spin Hamiltonian for spin-orbit-coupled ferromagnets on the honeycomb lattice. We find that the effective Hamiltonian for magnons, a quanta of spin-wave excitations from ordered states, is equivalent to the Haldane model for electrons ... More

End-to-End Pedestrian Collision Warning System based on a Convolutional Neural Network with Semantic SegmentationDec 20 2016Traditional pedestrian collision warning systems sometimes raise alarms even when there is no danger (e.g., when all pedestrians are walking on the sidewalk). These false alarms can make it difficult for drivers to concentrate on their driving. In this ... More

A Polynomial Kernel for Distance-Hereditary Vertex DeletionOct 23 2016A graph is distance-hereditary if for any pair of vertices, their distance in every connected induced subgraph containing both vertices is the same as their distance in the original graph. Distance hereditary graphs are exactly the graphs with rank-width ... More

Cooper-Pair Spin Current in a Strontium Ruthenate HeterostructureFeb 05 2018It has been recognized that the condensation of spin-triplet Cooper pairs requires not only the broken gauge symmetry but also the spin ordering as well. One consequence of this is the possibility of the Cooper-pair spin current analogous to the magnon ... More

Coherent Terahertz Spin-Wave Emission Associated with Ferrimagnetic Domain Wall DynamicsJun 02 2017We theoretically study the dynamics of ferrimagnetic domain walls in the presence of Dzyaloshinskii-Moriya interaction. We find that an application of a DC magnetic field can induce terahertz spin-wave emission by driving ferrimagnetic domain walls, which ... More

Deeply-Recursive Convolutional Network for Image Super-ResolutionNov 14 2015Nov 11 2016We propose an image super-resolution method (SR) using a deeply-recursive convolutional network (DRCN). Our network has a very deep recursive layer (up to 16 recursions). Increasing recursion depth can improve performance without introducing new parameters ... More

Accurate Image Super-Resolution Using Very Deep Convolutional NetworksNov 14 2015Nov 11 2016We present a highly accurate single-image super-resolution (SR) method. Our method uses a very deep convolutional network inspired by VGG-net used for ImageNet classification \cite{simonyan2015very}. We find increasing our network depth shows a significant ... More

Learning Low-Rank Approximation for CNNsMay 24 2019Low-rank approximation is an effective model compression technique to not only reduce parameter storage requirements, but to also reduce computations. For convolutional neural networks (CNNs), however, well-known low-rank approximation methods, such as ... More

Fast domain wall motion induced by antiferromagnetic spin dynamics at the angular momentum compensation temperature of ferrimagnetsMar 22 2017Antiferromagnetic spintronics is an emerging research field which aims to utilize antiferromagnets as core elements in spintronic devices. A central motivation toward this direction is that antiferromagnetic spin dynamics is expected to be much faster ... More

Spin-transfer torques for domain walls in antiferromagnetically coupled ferrimagnetsMar 08 2019Antiferromagnetic materials are outstanding candidates for next generation spintronic applications, because their ultrafast spin dynamics makes it possible to realize several orders of magnitude higher-speed devices than conventional ferromagnetic materials1. ... More

Low magnetic damping of ferrimagnetic GdFeCo alloysJun 13 2018We investigate the Gilbert damping parameter for rare earth (RE)-transition metal (TM) ferrimagnets over a wide temperature range. Extracted from the field-driven magnetic domain-wall mobility, the Gilbert damping parameter was as low as 0.0072 and was ... More

Covariant Functors and Asymptotic StabilityJul 30 2015Let R be a commutative Noetherian ring, I and J ideals of R and M a finitely generated R-module. Let F be a covariant R-linear functor from the category of finitely generated R-modules to itself. We first show that if F is coherent, then the sets of associated ... More

Effects of the globalization in the Korean financial marketsSep 13 2005Nov 15 2005We study the effect of globalization on the Korean market, one of the emerging markets. Some characteristics of the Korean market are different from those of the mature market according to the latest market data, and this is due to the influence of foreign ... More

Transfer Entropy Analysis of the Stock MarketSep 02 2005Sep 29 2005In terms of transfer entropy, we investigated the strength and the direction of information transfer in the US stock market. Through the directionality of the information transfer, the more influential company between the correlated ones can be found ... More

Using atomic layer deposition to hinder solvent decomposition in lithium ion batteries: first principles modeling and experimental studiesOct 06 2012Passivating lithium ion battery electrode surfaces to prevent electrolyte decomposition is critical for battery operations. Recent work on conformal atomic layer deposition (ALD) coating of anodes and cathodes has shown significant technological promise. ... More

Co-occurrence matrix analysis-based semi-supervised training for object detectionFeb 20 2018One of the most important factors in training object recognition networks using convolutional neural networks (CNNs) is the provision of annotated data accompanying human judgment. Particularly, in object detection or semantic segmentation, the annotation ... More

Group dynamics of the Japanese marketAug 03 2007We investigated the network structures of the Japanese stock market through the minimum spanning tree. We defined grouping coefficient to test the validity of conventional grouping by industrial categories, and found a decreasing in trend for the coefficient. ... More

Chaos and unpredictability in evolution of cooperation in continuous timeDec 16 2017Cooperators benefit others with paying costs. Evolution of cooperation crucially depends on the cost-benefit ratio of cooperation, denoted as $c$. In this work, we investigate the infinitely repeated prisoner's dilemma for various values of $c$ with four ... More

Grouping in the stock markets of Japan and KoreaNov 27 2005We investigated the temporally evolving network structures of the Japanese and Korean stock markets through the minimum spanning trees composed of listed stocks. We tested the validity of conventional grouping by industrial categories, and found a common ... More

The dynamics of bimeron skyrmions in easy-plane magnets induced by a spin supercurrentJan 01 2019May 21 2019We theoretically study the interaction of an isolated bimeron skyrmion in quasi-two-dimensional easy-plane magnets with a surrounding spin superfluid associated with spontaneously broken U(1) spin-rotational symmetry, revealing that skyrmion energy depends ... More

Structured Compression by Unstructured Pruning for Sparse Quantized Neural NetworksMay 24 2019Model compression techniques, such as pruning and quantization, are becoming increasingly important to reduce the memory footprints and the amount of computations. Despite model size reduction, achieving performance enhancement on devices is, however, ... More

Network Pruning for Low-Rank Binary IndexingMay 14 2019Pruning is an efficient model compression technique to remove redundancy in the connectivity of deep neural networks (DNNs). Computations using sparse matrices obtained by pruning parameters, however, exhibit vastly different parallelism depending on ... More

The Dynamics of Skyrmions in Easy-Plane Magnets induced by a Spin SupercurrentJan 01 2019We theoretically study the interaction of an isolated bimeron skyrmion in quasi-two-dimensional easy-plane magnets with a surrounding spin superfluid associated with spontaneously broken U(1) spin-rotational symmetry, revealing that skyrmion energy depends ... More

Temperature dependence of magnetic resonance in ferrimagnetic GdFeCo alloysJul 10 2019We provide a macroscopic theory and experimental results for magnetic resonances of antiferromagnetically-coupled ferrimagnets. Our theory, which interpolates the dynamics of antiferromagnets and ferromagnets smoothly, can describe ferrimagnetic resonances ... More

Auto-Meta: Automated Gradient Based Meta Learner SearchJun 11 2018Dec 10 2018Fully automating machine learning pipelines is one of the key challenges of current artificial intelligence research, since practical machine learning often requires costly and time-consuming human-powered processes such as model design, algorithm development, ... More

Chemically Induced Transformation of CVD-Grown Bilayer Graphene into Single Layer DiamondJan 08 2019Notwithstanding numerous density functional studies on the chemically induced transformation of multilayer graphene into a diamond-like film, a comprehensive convincing experimental proof of such a conversion is still lacking. We show that the fluorination ... More

Young Walls of Type $D^(2)_n+1$ and Strict PartitionsMay 12 2011May 18 2011We show that the number of reduced Young walls of type $D_{n+1}^{(2)}$ with $m$ blocks is independent of $n$ and the same as the number of strict partitions of $m$. Thus the principally specialized character $\chi_n^{\Lambda_0}(t)$ of $V(\Lambda_0)$ over ... More

Vanishing skyrmion Hall effect at the angular momentum compensation temperature of a ferrimagnetSep 03 2018Charged particles exhibit the Hall effect in the presence of magnetic fields. Analogously, ferromagnetic skyrmions with non-zero topological charges and finite fictitious magnetic fields exhibit the skyrmion Hall effect, which is detrimental for applications. ... More

Auslander-Reiten quiver of type D and generalized quantum affine Schur-Weyl dualityJun 17 2014Jun 22 2015We first provide an explicit combinatorial description of the Auslander-Reiten quiver $\Gamma^Q$ of finite type $D$. Then we can investigate the categories of finite dimensional representations over the quantum affine algebra $U_q'(D^{(i)}_{n+1})$ $(i=1,2)$ ... More

The Denominators of normalized R-matrices of types $A_{2n-1}^{(2)}$, $A_{2n}^{(2)}$, $B_{n}^{(1)}$ and $D_{n+1}^{(2)}$Apr 27 2014Jul 03 2014Denominators of normalized $R$-matrices provide important information on finite dimensional representations over quantum affine algebras, and over quiver Hecke algebras by the generalized quantum affine Schur-Weyl duality functors. We compute the denominators ... More

Probing the Band Structure of LaTe_2 Using Angle Resolved Photoemission SpectroscopyMar 21 2007Jun 22 2007With the current interest in the rare-earth tellurides as high temperature charge density wave materials, a greater understanding of the physics of these systems is needed, particularly in the case of the ditellurides. We report a detailed study of the ... More

Finite F-type and F-abundant modulesMar 01 2016In this note we introduce and study basic properties of two types of modules over a commutative noetherian ring $R$ of positive prime characteristic. The first is the category of modules of finite $F$-type. These objects include reflexive ideals representing ... More

Simulation study of dose enhancement in a cell due to nearby carbon and oxygen in particle radiotherapyMar 13 2015The aim of this study is to investigate the dose-deposition enhancement by alpha-particle irradiation in a cellular model using carbon and oxygen chemical compositions.A simulation study was performed to study dose enhancement due to carbon and oxygen ... More

Emergence of robust 2D skyrmions in SrRuO3 ultrathin film without the capping layerOct 03 2018Magnetic skyrmions have fast evolved from a novelty, as a realization of topologically protected structure with particle-like character, into a promising platform for new types of magnetic storage. Significant engineering progress was achieved with the ... More

Atomic-scale observation and manipulation of plaquette antiferromagnetic order in iron-based superconductorAug 02 2016Jun 19 2017The symmetry requirement and the origin of magnetic orders coexisting with superconductivity have been strongly debated issues of iron-based superconductors (FeSCs). Observation of C$_4$-symmetric antiferromagnetism in violation of the inter-band nesting ... More

Landau-Lifshitz theory of the thermomagnonic torqueMay 04 2015We derive the thermomagnonic torque associated with smooth magnetic textures subjected to a temperature gradient, in the framework of the stochastic Landau-Lifshitz-Gilbert equation. Our approach captures on equal footing two distinct contributions: (1) ... More

Pinning of a Bloch point by an atomic latticeJan 28 2013Sep 13 2013Bloch points are magnetic topological defects. The discrete nature of a magnetic lattice creates a periodic potential that can pin a Bloch point. The pinning force is of the order of the exchange constant, a few piconewtons in a typical ferromagnet (permalloy). ... More

Astrometrically Registered Simultaneous Observations of the 22 GHz H$_2$O and the 43GHz SiO masers towards R Leonis Minoris using KVN and Source/Frequency Phase ReferencingAug 15 2014Oxygen-rich Asymptotic Giant Branch (AGB) stars can be intense emitters of SiO ($v$=1 and 2, J=1$\rightarrow$0) and H$_2$O maser lines at 43 and 22 GHz, respectively. VLBI observations of the maser emission provide a unique tool to probe the innermost ... More

Topological Effects on Quantum Phase Slips in Superfluid Spin TransportNov 08 2015We theoretically investigate effects of quantum fluctuations on superfluid spin transport through easy-plane quantum antiferromagnetic spin chains in the large-spin limit. Quantum fluctuations give rise to decaying of spin supercurrent by unwinding the ... More

U(1) symmetry of the spin-orbit coupled Hubbard model on the Kagome latticeJul 14 2015Oct 29 2015We study the symmetry properties of the single-band Hubbard model with general spin-orbit coupling (SOC) on the Kagome lattice. We show that the global U(1) spin-rotational symmetry is present in the Hubbard Hamiltonian owing to the inversion symmetry ... More

The East-Asian VLBI NetworkDec 11 2015The East-Asian VLBI Network (EAVN) is the international VLBI facility in East Asia and is conducted in collaboration with China, Japan, and Korea. The EAVN consists of VLBI arrays operated in each East Asian country, containing 21 radio telescopes and ... More

A broad HCO+ absorption line associated with the circumnuclear torus of NGC 1052Feb 22 2019In the circumnuclear region of the nearby radio galaxy NGC~1052. Our $\lambda$3mm VLBI observations with the Korean VLBI Network have spatially resolved the broad HCO$^{+}$ absorption at a velocity range of 1350--1850 km~s$^{-1}$ against a double-sided ... More

Fast Vortex Oscillations in a Ferrimagnetic Disk near the Angular Momentum Compensation PointMay 25 2017Jun 30 2017We theoretically study the oscillatory dynamics of a vortex core in a ferrimagnetic disk near its angular momentum compensation point, where the spin density vanishes but the magnetization is finite. Due to the finite magnetostatic energy, a ferrimagnetic ... More

Classification based Grasp Detection using Spatial Transformer NetworkMar 04 2018Robotic grasp detection task is still challenging, particularly for novel objects. With the recent advance of deep learning, there have been several works on detecting robotic grasp using neural networks. Typically, regression based grasp detection methods ... More

Polynomial splittings of correction terms and doubly slice knotsNov 23 2016We show that if the connected sum of two knots with coprime Alexander polynomials is doubly slice, then the Ozsv\'ath-Szab\'o correction terms as smooth double sliceness obstructions vanish for both knots. Recently, Jeffrey Meier gave smoothly slice knots ... More

Single dish performance of KVN 21-m radio telescopes:Simultaneous observations at 22 and 43 GHzOct 18 2011We report simultaneous multi-frequency observing performance at 22 and 43 GHz of the 21-m shaped-Cassegrain radio telescopes of the Korean VLBI Network (KVN). KVN is the first millimeter-dedicated VLBI network in Korea having a maximum baseline length ... More

High-performance monolayer MoS2 field-effect transistor with large-scale nitrogen-doped graphene electrodes for Ohmic contactJul 18 2019A finite Schottky barrier and large contact resistance between monolayer MoS2 and electrodes are the major bottlenecks in developing high-performance field-effect transistors (FETs) that hinder the study of intrinsic quantum behaviors such as valley-spin ... More

Secondary Upsilon invariants of knotsOct 17 2016The knot invariant Upsilon, defined by Ozsvath, Stipsicz, and Szabo, induces a homomorphism from the smooth knot concordance group to the group of piecewise linear functions on the interval [0,2]. Here we define a set of related secondary invariants, ... More

Parameter Estimation for Thurstone Choice ModelsApr 29 2017We consider the estimation accuracy of individual strength parameters of a Thurstone choice model when each input observation consists of a choice of one item from a set of two or more items (so called top-1 lists). This model accommodates the well-known ... More

Non-splittability of the rational homology cobordism group of 3-manifoldsNov 15 2012The smooth rational homology cobordism group of rational homology three spheres, T, contains subgroups T_p generated by 3-manifolds with first homology p-torsion, where p is a prime. Rochlin's theorem and gauge theoretic methods show that the inclusion ... More

Identities from representation theoryApr 30 2018We give a new Jacobi--Trudi-type formula for characters of finite-dimensional irreducible representations in type $C_n$ using characters of the fundamental representations and non-intersecting lattice paths. We give equivalent determinant formulas for ... More

Optimal Cluster Recovery in the Labeled Stochastic Block ModelOct 20 2015May 21 2016We consider the problem of community detection or clustering in the labeled Stochastic Block Model (LSBM) with a finite number $K$ of clusters of sizes linearly growing with the global population of items $n$. Every pair of items is labeled independently ... More

Mechanical Actuation of Magnetic Domain-Wall MotionJun 17 2016We theoretically study the motion of a magnetic domain wall induced by transverse elastic waves in a one-dimensional magnetic wire, which respects both rotational and translational symmetries. By invoking the conservation of the associated total angular ... More

Thermally-Activated Phase Slips in Superfluid Spin Transport in Magnetic WiresSep 02 2015We theoretically study thermally-activated phase slips in superfluid spin transport in easy-plane magnetic wires within the stochastic Landau-Lifshitz-Gilbert phenomenology, which runs parallel to the Langer-Ambegaokar-McCumber-Halperin theory for thermal ... More

Identification of the Au coverage and structure of the Au/Si(111)-5x2 surfaceMay 19 2014We identify the atomic structure of the Au/Si(111)-5x2 surface by using density functional theory calculations. With seven Au atoms per unit cell, our model forms a bona fide 5x2 atomic structure, which is energetically favored over the leading model ... More

On embeddings of the Grassmannian $Gr(2,m)$ into the Grassmannian $Gr(2,n)$Sep 22 2016Feb 15 2017In this {paper}, we consider holomorphic embeddings of $Gr(2,m)$ into $Gr(2,n)$. We study such embeddings by finding all possible total Chern classes of the pull-back of the universal bundles under these embeddings. Using the relations between Chern classes ... More

Nonlocal Spin Transport Mediated by a Vortex Liquid in SuperconductorsJun 20 2018Departing from the conventional view on superconducting vortices as a parasitic source of dissipation for charge transport, we propose to use mobile vortices as topologically-stable information carriers for spin transport. To this end, we start by constructing ... More

The First Very Long Baseline Interferometry Image of 44 GHz Methanol Maser with the KVN and VERA Array (KaVA)Jun 09 2014Jun 11 2014We have carried out the first very long baseline interferometry (VLBI) imaging of 44 GHz class I methanol maser (7_{0}-6_{1}A^{+}) associated with a millimeter core MM2 in a massive star-forming region IRAS 18151-1208 with KaVA (KVN and VERA Array), which ... More

Topological spin transport by Brownian diffusion of domain wallsJul 31 2015Dec 16 2015We propose thermally-populated domain walls (DWs) in an easy-plane ferromagnetic insulator as robust spin carriers between two metals. The chirality of a DW, which serves as a topological charge, couples to the metal spin accumulation via spin-transfer ... More

Propulsion of a domain wall in an antiferromagnet by magnonsJun 23 2014We analyze the dynamics of a domain wall in an easy-axis antiferromagnet driven by circularly polarized magnons. Magnons pass through a stationary domain wall without reflection and thus exert no force on it. However, they reverse their spin upon transmission, ... More

Mechanical Actuation of Magnetic Domain-Wall MotionJun 17 2016Nov 02 2016We theoretically study the motion of a magnetic domain wall induced by transverse elastic waves in a one-dimensional magnetic wire, which respects both rotational and translational symmetries. By invoking the conservation of the associated total angular ... More

Topological Transport of Vorticity in Heisenberg MagnetsOct 24 2018Dec 21 2018We study a robust topological transport carried by vortices in a thin film of an easy-plane ferromagnetic insulator between two metal contacts. A vortex, which is a nonlocal topological spin texture in two-dimensional magnets, exhibits some beneficial ... More

Jet Kinematics of the Quasar 4C +21.35 from Observations with the KaVA Very Long Baseline Interferometry ArrayApr 05 2019We present the jet kinematics of the flat spectrum radio quasar (FSRQ) 4C +21.35 using time-resolved KaVA very long baseline interferometry array radio maps obtained from September 2014 to July 2016. During two out of three observing campaigns, observations ... More

Thermophoresis of an Antiferromagnetic SolitonMar 26 2015Jul 08 2015We study dynamics of an antiferromagnetic soliton under a temperature gradient. To this end, we start by phenomenologically constructing the stochastic Landau-Lifshitz-Gilbert equation for an antiferromagnet with the aid of the fluctuation-dissipation ... More

Atomic and electronic structure of the $\sqrt{3}$$\times$$\sqrt{3}$ silicene phase on Ag(111): density-functional calculationsFeb 26 2016Density-functional theory calculations are used to verify the atomic structure of the $\sqrt{3}$$\times$$\sqrt{3}$ silicene phase grown on the Ag(111) surface. Recent experimental studies strongly suggested that the previous double-layer silicene model ... More

Majorana Fermion Rides on a Magnetic Domain WallFeb 07 2015We propose using a mobile magnetic domain wall as a host of zero-energy Majorana fermions in a spin-orbit coupled nanowire sandwiched by two ferromagnetic strips and deposited on an $s$-wave superconductor. The ability to control domain walls by thermal ... More

Topological Transport of Vorticity in Heisenberg MagnetsOct 24 2018May 09 2019We study a robust topological transport carried by vortices in a thin film of an easy-plane ferromagnetic insulator between two metal contacts. A vortex, which is a nonlocal topological spin texture in two-dimensional magnets, exhibits some beneficial ... More

Spin Analogues of Superconductivity and the Integer Quantum Hall Effect in an Array of Spin ChainsJan 06 2017Motivated by the successful idea of using weakly-coupled quantum electronic wires to realize the quantum Hall effects and the quantum spin Hall effects, we theoretically construct two systems composed of weakly-coupled quantum spin chains, which can exhibit ... More

Magnetic Domain Wall Floating on a Spin SuperfluidAug 02 2016We theoretically investigate the transfer of angular momentum between a spin superfluid and a domain wall in an exchange coupled easy-axis and easy-plane magnetic insulator system. A domain wall in the easy-axis magnet absorbs spin angular momentum via ... More

Stabilization of the skyrmion crystal phase in thin-film antiferromagnetsJun 17 2018We investigate the formation and stability of the skyrmion crystal phase in antiferromagnetic thin films subjected to fieldlike torques such as, e.g., those induced by an electric current in CuMnAs and Mn$_{2}$Au via the inverse spin-galvanic effect. ... More

On embeddings of the Grassmannian $Gr(2,m)$ into the Grassmannian $Gr(2,n)$Sep 22 2016In this paper, we consider holomorphic embeddings of $Gr(2,m)$ into $Gr(2,n)$. We can study such embeddings by finding all possible total Chern classes of the pull-back of the universal bundles under these embeddings. To do this, we use the relations ... More

Incorporating User Interaction into Imperative LanguagesAug 16 2015Adding versatile interactions to imperative programming -- C, Java and Android -- is an essential task. Unfortunately, existing languages provide little constructs for user interaction. We propose a computability-logical approach to user interaction. ... More

Logic Programming with Macro ConnectivesAug 13 2015Jun 21 2016Logic programming such as Prolog is often sequential and slow because each execution step processes only a single, $micro$ connective. To fix this problem, we propose to use $macro$ connectives as the means of improving both readability and performance. ... More

Intersection theoretic properties on the moduli space of genus 0 stable maps to a semipositive symplectic 4-manifoldFeb 14 2005Feb 03 2008We characterize transversality, non-transversality properties on the moduli space of genus 0 stable maps to a semipositive symplectic manifold of dimension 4, when GW([point],...,[point]) is enumerative. In particular, we show that the intersection theoretic ... More

Study on the microwave ion source of 100-MeV proton linacJun 14 2016A microwave ion source is used as an ion source of 100-MeV proton accelerator at Korea Multipurpose Accelerator Complex (KOMAC). The specifications of the ion source are 50 keV in energy and 20 mA in peak current. The plasma is operated in CW mode using ... More

Real aspects of the moduli space of genus zero stable mapsMay 08 2003Dec 14 2007We show that the moduli space of genus zero stable maps is a real projective variety if the target space is a smooth convex real projective variety. We show that evaluation maps, forgetful maps are real morphisms. We analyze the real part of the moduli ... More

Real Gromov-Witten invariants on the moduli space of genus 0 stable maps to a smooth rational projective spaceOct 18 2004Dec 14 2007We characterize transversality, non-transversality properties on the moduli space of genus 0 stable maps to a rational projective surface. If a target space is equipped with a real structure, i.e, anti-holomorphic involution, then the results have real ... More

Structural Conditions for Full MHD EquationsOct 23 2007Jul 02 2008In this paper, we investigate the characteristic structure of the full equations of magnetohydrodynamics (MHD) and show that it satisfies the hypotheses of a general variable-multiplicity stability frame- work introduced by Metivier and Zumbrun, thereby ... More

A devil's staircase from rotations and irrationality measures for Liouville numbersSep 11 2007From Sturmian and Christoffel words we derive a strictly increasing function $\Delta:[0,\infty)\to\mathbb{R}$. This function is continuous at every irrational point, while at rational points, left-continuous but not right-continuous. Moreover, it assumes ... More

Combinatorial Auslander-Reiten quivers and reduced expressionsSep 16 2015In this paper, we introduce the notion of combinatorial Auslander-Reiten (AR) quivers. Combinatorial AR quivers can be understood as a generalization of AR quivers and each combinatorial AR quiver realizes a convex partial order on a set of positive roots ... More

Topologically slice knots of smooth concordance order twoDec 29 2012May 14 2014The existence of topologically slice knots that are of infinite order in the knot concordance group followed from Freedman's work on topological surgery and Donaldson's gauge theoretic approach to 4-manifolds. Here, as an application of Ozsvath and Szabo's ... More

From vertical-cavities to hybrid metal/photonic-crystal nanocavities: Towards high-efficiency nanolasersSep 01 2011We provide a numerical study showing that a bottom reflector is indispensable to achieve unidirectional emission from a photonic-crystal (PhC) nanolaser. First, we study a PhC slab nanocavity suspended over a flat mirror formed by a dielectric or metal ... More

Real-Time, Highly Accurate Robotic Grasp Detection using Fully Convolutional Neural Networks with High-Resolution ImagesSep 16 2018Robotic grasp detection for novel objects is a challenging task, but for the last few years, deep learning based approaches have achieved remarkable performance improvements, up to 96.1% accuracy, with RGB-D data. In this paper, we propose fully convolutional ... More

Down-Scaling with Learned Kernels in Multi-Scale Deep Neural Networks for Non-Uniform Single Image DeblurringMar 25 2019Multi-scale approach has been used for blind image / video deblurring problems to yield excellent performance for both conventional and recent deep-learning-based state-of-the-art methods. Bicubic down-sampling is a typical choice for multi-scale approach ... More

Catalan triangle numbers and binomial coefficientsJan 25 2016We prove that any binomial coefficient can be written as weighted sums along rows of the Catalan triangle. The coefficients in the sums form a triangular array, which we call the {\em alternating Jacobsthal triangle}. We study various subsequences of ... More

Monoidal categories of modules over quantum affine algebras of type A and BOct 18 2017We construct an exact tensor functor from the category $\mathcal{A}$ of finite-dimensional graded modules over the quiver Hecke algebra of type $A_\infty$ to the category $\mathscr C_{B^{(1)}_n}$ of finite-dimensional integrable modules over the quantum ... More