Results for "Seonghoon Woo"

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Large voltage-induced modification of spin-orbit torques in Pt/Co/GdOxNov 22 2014We report on large modifications of current-induced spin-orbit torques in a gated Pt/Co/Gd-oxide microstrip due to voltage-driven O$^{2-}$ migration. The Slonczewski-like and field-like torques are quantified using a low-frequency harmonic technique based ... More
Observation of room temperature magnetic skyrmions and their current-driven dynamics in ultrathin Co filmsFeb 25 2015Magnetic skyrmions are topologically-protected spin textures that exhibit fascinating physical behaviors and large potential in highly energy efficient spintronic device applications. The main obstacles so far are that skyrmions have been observed in ... More
Efficient geometric integrators for nonadiabatic quantum dynamics. II. The diabatic representationMar 12 2019Apr 17 2019Exact nonadiabatic quantum evolution preserves many geometric properties of the molecular Hilbert space. In a companion paper [S. Choi and J. Van\'{\i}\v{c}ek, 2019], we presented numerical integrators of arbitrary-order of accuracy that preserve these ... More
Observation of magnetic skyrmion crystals in a van der Waals ferromagnet Fe3GeTe2Jul 02 2019Since the discovery of long-range magnetic orders in the two-dimensional (2D) van der Waals (vdW) crystals, significant interest on such 2D magnets has emerged, inspired by their appealing physical properties and integration with other 2D family for unique ... More
Efficient geometric integrators for nonadiabatic quantum dynamics in the adiabatic basisFeb 12 2019The split-operator algorithm is popular for nonadiabatic quantum dynamics because it is explicit, easy to implement, and preserves many geometric invariants of the exact evolution; however, the algorithm can only be used in the diabatic basis, or, more ... More
Magnetic skyrmion artificial synapse for neuromorphic computingJul 01 2019Since the discovery of magnetic skyrmions achieved one decade ago, there have been significant efforts to bring the virtual particles into fully functional devices, inspired by their fascinating physical and topological properties suitable for future ... More
Logitron: Perceptron-augmented classification model based on an extended logistic loss functionApr 05 2019Classification is the most important process in data analysis. However, due to the inherent non-convex and non-smooth structure of the zero-one loss function of the classification model, various convex surrogate loss functions such as hinge loss, squared ... More
A decade of skyrmionics: Writing, deleting, reading and processing magnetic skyrmions roward spintronic applicationsJun 11 2019The field of skyrmionics has been actively investigated across a wide range of topics during the last decade. In this topical review, we review and discuss key results and findings in skyrmionics since the first experimental observation of magnetic skyrmions ... More
The Bregman-Tweedie Classification ModelJul 16 2019This work proposes the Bregman-Tweedie classification model and analyzes the domain structure of the extended exponential function, an extension of the classic generalized exponential function with additional scaling parameter, and related high-level ... More
Interval pattern avoidance for arbitrary root systemsNov 11 2006We extend the idea of interval pattern avoidance defined by Yong and the author for $S_n$ to arbitrary Weyl groups using the definition of pattern avoidance due to Billey and Braden, and Billey and Postnikov. We show that, as previously shown by Yong ... More
Some cases on Strassen additive conjectureJun 09 2014Jun 22 2014In this article, we verify the additivity for rank of a sum of coprime monomials and bivariate polynomials generalizing the result in (\cite{CCG}). We also show similar results hold for cactus rank.
A decade of skyrmionics: Writing, deleting, reading and processing magnetic skyrmions toward spintronic applicationsJun 11 2019Jun 12 2019The field of skyrmionics has been actively investigated across a wide range of topics during the last decade. In this topical review, we review and discuss key results and findings in skyrmionics since the first experimental observation of magnetic skyrmions ... More
Multiplicities of the Most Singular Point on Schubert varieties on Gl(n)/B for n=5,6Jul 09 2004We calculate using Macaulay 2 the multiplicities of the most singular point on Schubert varieties on Gl(n)/B for $n=5,6$. The method of computation is described and tables of the results are included.
Catalan numbers and Schubert polynomials for $w=1(n+1)... 2$Jul 09 2004We show that the Schubert polynomial S_w specializes to the Catalan number C_n when $w=1(n+1)...2$. Several proofs of this result as well as a q-analog are given. An application to the singularities of Schubert varieties is given.
Deterministic creation and deletion of a single magnetic skyrmion observed by direct time-resolved X-ray microscopyJun 21 2017Apr 06 2018Spintronic devices based on magnetic skyrmions are a promising candidate for next-generation memory applications due to their nanometre-size, topologically-protected stability and efficient current-driven dynamics. Since the recent discovery of room-temperature ... More
Efficient geometric integrators for nonadiabatic quantum dynamics. I. The adiabatic representationFeb 12 2019Apr 17 2019Geometric integrators of the Schr\"{o}dinger equation conserve exactly many invariants of the exact solution. Among these integrators, the split-operator algorithm is explicit and easy to implement, but, unfortunately, is restricted to systems whose Hamiltonian ... More
Spin-orbit torque-driven skyrmion dynamics revealed by time-resolved X-ray microscopyMay 25 2017Magnetic skyrmions are topologically-protected spin textures with attractive properties suitable for high-density and low-power spintronic device applications. Much effort has been dedicated to understanding the dynamical behaviours of the magnetic skyrmions. ... More
A study on the performance of similarity indices and its relationship with link prediction: a two-state random network caseSep 03 2018Sep 05 2018Similarity index measures the topological proximity of node pairs in a complex network. Numerous similarity indices have been defined and investigated, but the dependency of structure on the performance of similarity indices has not been sufficiently ... More
Ideal Strength of Doped GrapheneNov 02 2012Feb 19 2013While the mechanical distortions change the electronic properties of graphene significantly, the effects of electronic manipulation on its mechanical properties have not been known. Using first-principles calculation methods, we show that, when graphene ... More
Vortex Dynamics in an Annular Bose-Einstein CondensateJun 25 2012Jul 25 2012We theoretically show that the topology of a non-simply-connected annular atomic Bose-Einstein condensate enforces the inner surface waves to be always excited with outer surface excitations and that the inner surface modes are associated with induced ... More
Accuracy Test for Link Prediction in terms of Similarity Index: The Case of WS and BA ModelsMar 10 2015Link prediction is a technique that uses the topological information in a given network to infer the missing links in it. Since past research on link prediction has primarily focused on enhancing performance for given empirical systems, negligible attention ... More
A Gröbner basis for Kazhdan-Lusztig idealsSep 03 2009Nov 11 2011Kazhdan-Lusztig ideals, a family of generalized determinantal ideals investigated in [Woo-Yong '08], provide an explicit choice of coordinates and equations encoding a neighbourhood of a torus-fixed point of a Schubert variety on a type A flag variety. ... More
Directional current-current correlation functions in a two-species hard-core bosons in one dimensional finite lattice: An exact diagonalization studyMar 29 2017Jun 01 2018We study a model for two-species hard-core bosons in one dimension. In this model, the same-species bosons have a hard-core condition at the same site, while different-species bosons are allowed to occupy the same site with a local interaction $U$. At ... More
Perturbing Around A Warped Product Of AdS_4 and Seven-EllipsoidJul 06 2009Aug 08 2009We compute the spin-2 Kaluza-Klein modes around a warped product of AdS_4 and a seven-ellipsoid. This background with global G_2 symmetry is related to a U(N) x U(N) N=1 superconformal Chern-Simons matter theory with sixth order superpotential. The mass-squared ... More
Supersymmetric Domain Wall and RG Flow from 4-Dimensional Gauged N=8 SupergravityNov 14 2000Dec 21 2000By studying various, known extrema of 1) SU(3) sectors, 2) SO(5) sectors and 3) SO(3)xSO(3) sectors of gauged N =8 supergravity in four-dimensions, one finds that the deformation of seven sphere \S^7 gives rise to non-trivial renormalization group(RG) ... More
Analytical Gradient Theory for Strongly Contracted (SC-) and Partially Contracted (PC-) N-Electron Valence State Perturbation Theory (NEVPT2)Jul 24 2019Jul 31 2019An analytical gradient theory for single-state N-electron valence state perturbation theory (NEVPT2), using both strongly contracted (SC) and partially contracted (PC) internal contraction schemes, is developed. We demonstrate the utility of the developed ... More
Three-point bounds for energy minimizationMar 02 2011Jun 24 2013Three-point semidefinite programming bounds are one of the most powerful known tools for bounding the size of spherical codes. In this paper, we use them to prove lower bounds for the potential energy of particles interacting via a pair potential function. ... More
Algebraic Singularity Method for Mass Measurements with Missing EnergyOct 07 2009Feb 16 2010We propose a novel generalized method for mass measurements based on phase space singularity structures that can be applied to any event topology with missing energy. Our method subsumes the well-known end-point and transverse mass methods and yields ... More
Bruhat graphs and pattern avoidanceJul 24 2011Jul 19 2013We characterize permutations whose Bruhat graphs can be drawn in the plane and those whose Bruhat graphs can be drawn in the torus. In particular, we show these properties are characterized by avoiding finitely many permutations.
Which Schubert varieties are local complete intersections?Nov 26 2011We characterize by pattern avoidance the Schubert varieties for GL_n which are local complete intersections (lci). For those Schubert varieties which are local complete intersections, we give an explicit minimal set of equations cutting out their neighborhoods ... More
$γ$ Doradus Pulsations in the Eclipsing Binary Star KIC 6048106Sep 20 2016We present the ${\it Kepler}$ photometry of KIC 6048106 exhibiting O'Connell effect and multiperiodic pulsations. Including a starspot on either of the components, light-curve synthesis indicates that this system is a semi-detached Algol with a mass ratio ... More
Consistent-Histories Description of A World of Increasing EntropyJan 18 1999Sep 01 1999A distinction is made between two kinds of consistent histories: (1) robust histories consistent by virtue of decoherence, and (2) verifiable histories consistent through the existence of accessible records. It is events in verifiable histories which ... More
Formulas for Chebotarev densities of Galois extensions of number fieldsJul 04 2018We generalize the Chebotarev density formulas of Dawsey (2017) and Alladi (1977) to the setting of arbitrary finite Galois extensions of number fields $L/K$. In particular, if $C \subset G = \textrm{Gal}(L/K)$ is a conjugacy class, then we establish that ... More
Domain Wall from Gauged d=4, N=8 Supergravity: Part ISep 03 2001Apr 17 2002By studying already known extrema of non-semi-simple Inonu-Wigner contraction CSO(p, q)^{+} and non-compact SO(p, q)^{+}(p+q=8) gauged N=8 supergravity in 4-dimensions developed by Hull sometime ago, one expects there exists nontrivial flow in the 3-dimensional ... More
The Gauge Dual of A Warped Product of AdS_4 and A Squashed and Stretched Seven-ManifoldAug 18 2009Dec 16 2009Corrado, Pilch and Warner in 2001 have found the second 11-dimensional solution where the deformed geometry of S^7 in the lift contains S^2 x S^2. We identify the gauge dual of this background with the theory described by Franco, Klebanov and Rodriguez-Gomez ... More
Renormalization of Hénon map in arbitrary dimension I : Universality and reduction of ambient spaceJun 07 2015Jun 23 2015Period doubling H\'enon renormalization of strongly dissipative maps is generalized in arbitrary finite dimension. In particular, a small perturbation of toy model maps with dominated splitting has invariant $C^r$ surfaces embedded in higher dimension ... More
Mask formulas for cograssmannian Kazhdan-Lusztig polynomialsNov 04 2010We give two contructions of sets of masks on cograssmannian permutations that can be used in Deodhar's formula for Kazhdan-Lusztig basis elements of the Iwahori-Hecke algebra. The constructions are respectively based on a formula of Lascoux-Schutzenberger ... More
Feedback and the fudamental line of low-luminosity LSB/dwarf galaxiesOct 20 2002Dec 12 2003We study in simple terms the role of feedback in establishing the scaling relations of low-surface-brightness and dwarf galaxies with stellar masses in the range 6x10^5 <M*< 3x10^10 Msun. These galaxies, as measured from SDSS and in the Local Group, show ... More
Power sum decompositions of defining equations of reflection arrangementsApr 26 2013Apr 02 2014We determine the Waring rank of the fundamental skew invariant of any complex reflection group whose highest degree is a regular number. This includes all irreducible real reflection groups.
Hyers-Ulam stability of parabolic Möbius difference equationAug 29 2017The linear fractional map $ g(z) = \frac{az+ b}{cz + d} $ on the Riemann sphere with complex coefficients $ ad-bc = 1 $ is and $ a+d = \pm 2 $, then $ g $ is called {\em parabolic} M\"obius map. Let $ \{ b_n \}_{n \in \mathbb{N}_0} $ be the solution of ... More
N=8 Gauged Supergravity Theory and N=6 Superconformal Chern-Simons Matter TheoryJan 29 2009Mar 09 2010By studying the previously known holographic N=4 supersymmetric renormalization group flow(Gowdigere-Warner) in four dimensions, we find the mass deformed Chern-Simons matter theory which has N=4 supersymmetry by adding the four mass terms among eight ... More
Domain Wall from Gauged d=4, N=8 Supergravity: Part IISep 16 2002Nov 10 2003The scalar potentials of the non-semi-simple CSO(p,8-p)(p=7,6,5) gaugings of N=8 supergravity are studied for critical points. The CSO(7,1) gauging has no G_2-invariant critical points, the CSO(6,2) gauging has three new SU(3)-invariant AdS critical points ... More
Holographic N=1 Supersymmetric Membrane FlowsApr 05 2010Jul 25 2010The M-theory lift of N=2 SU(3) x U(1)_R-invariant RG flow via a combinatorical use of the 4-dimensional flow and 11-dimensional Einstein-Maxwell equations was found previously. By taking the three internal coordinates differently and preserving only SU(3) ... More
On positiveness and contractiveness of the integral operator arising from the beam deflection problem on elastic foundationAug 21 2014We provide a complete proof that there are no nontrivial eigenvalues of the integral operator $\mathcal{K}_l$ outside the interval $(0,1/k)$. $\mathcal{K}_l$ arises naturally from the deflection problem of a beam with length $l$ resting horizontally on ... More
Global Classical Solutions to the Relativistic Boltzmann Equation without Angular Cut-offJan 12 2016Jan 22 2016We prove the unique existence and exponential decay of global in time classical solutions to the special relativistic Boltzmann equation without any angular cut-off assumptions with initial perturbations in some weighted Sobolev spaces. We consider perturbations ... More
Understanding Kondo Peak Splitting and the Mechanism of Cohernt Transport in a Single-Electron TransistorFeb 11 2007Oct 01 2007The peculiar behavior of Kondo peak splitting under a magnetic field and bias can be explained by calculating the nonequilibrium retarded Green's function via the nonperturbative dynamical theory (NDT). In the NDT, the application of a lead-dot-lead system ... More
Structure of our Galactic Bulge from CN MeasurementsApr 19 2019The double red clumps (DRCs) are now dominantly believed to be the strong observational line of evidence of the so-called X-shaped Galactic bar structures. Recently, Lee et al. reported a subtle mean \ds\ difference between the DRCs and suggested a dichotomic ... More
Multiple stellar populations of globular clusters from homogeneous Ca--CN photometry. IV. Toward precision populational taggingJan 28 2019Apparently similar but multifaceted photometric systems are currently being used to investigate the multiple stellar populations in globular clusters, without the concrete general agreement on the definition of the multiple populations. In recent years, ... More
Hyers-Ulam stability of hyperbolic Möbius difference equationAug 29 2017Hyers-Ulam stability of the difference equation with the initial point $ z_0 $ as follows $$ z_{i+1} = \frac{az_i + b}{cz_i + d} $$ is investigated for complex numbers $ a,b,c $ and $ d $ where $ ad - bc = 1 $, $ c \neq 0 $ and $a + d \in \mathbb{R} \setminus ... More
Renormalization of $C^r$ Hénon map : Two dimensional embedded map in three dimensionDec 29 2014We study renormalization of highly dissipative analytic three dimensional H\'enon maps $$ F(x,y,z) = (f(x) - \varepsilon(x,y,z),\ x,\ \delta(x,y,z)) $$ where $ \varepsilon(x,y,z) $ is a sufficiently small perturbation of $ \varepsilon_{2d}(x,y) $. Under ... More
Governing Singularities of Schubert VarietiesMar 12 2006Jun 29 2006We present a combinatorial and computational commutative algebra methodology for studying singularities of Schubert varieties of flag manifolds. We define the combinatorial notion of *interval pattern avoidance*. For "reasonable" invariants P of singularities, ... More
Matter-wave frequency comb generation in dissipatively coupled microcavitiesSep 12 2018Optical frequency combs generated from mode-locked lasers have revolutionized high-precision metrology and spectroscopy. Recently, chip-scale and energy efficient micro-combs have been produced using microresonators and quantum cascade lasers via cascaded ... More
On the metallicity distribution of the peculiar globular cluster M22Aug 30 2016In our previous study, we showed that the peculiar globular cluster (GC) M22 contains two distinct stellar populations, namely the Ca-w and Ca-s groups with different physical properties, having different chemical compositions, spatial distributions and ... More
Multiple Stellar Populations of Globular Clusters from Homogenous Ca by Photometry I. M22 (NGC 6656)May 30 2015We investigate the multiple stellar populations in one of peculiar globular clusters (GCs) M22 using new ground-based wide-field Ca by and HST/WFC3 photometry with equivalent passbands, confirming our previous result that M22 has a distinctive red-giant ... More
Multiple stellar populations of globular clusters from homogeneous Ca-Cn photometry. II. M5 (NGC 5904) and a new filter systemJun 24 2017Using our ingeniously designed new filter systems, we investigate the multiple stellar populations of the RGB and AGB in the GC M5. Our results are the following. (1) Our cn_jwl index accurately traces the nitrogen abundances in M5, while other color ... More
Analytical Gradient Theory for Strongly Contracted (SC-) and Partially Contracted (PC-) N-Electron Valence State Perturbation Theory (NEVPT2)Jul 24 2019The analytical gradient theory for single-state N-electron valence state perturbation theory (NEVPT2), with both strong contracted (SC-) and partially contracted (PC-) internal contraction schemes, is developed. The SC-NEVPT2 analytical gradients exhibit ... More
On the zeros of a class of modular functionsJul 11 2018Jul 13 2018We generalize a number of works on the zeros of certain level 1 modular forms to a class of weakly holomorphic modular functions whose $q$-expansions satisfy \[ f_k(A, \tau) \colon = q^{-k}(1+a(1)q+a(2)q^2+...) + O(q),\] where $a(n)$ are numbers satisfying ... More
Towards An N=1 SU(3)-Invariant Supersymmetric Membrane Flow In Eleven-Dimensional SupergravityJan 21 2010Apr 08 2010The M-theory lift of N=1 G_2-invariant RG flow via a combinatoric use of the 4-dimensional RG flow and 11-dimensional Einstein-Maxwell equations was found some time ago. The 11-dimensional metric, a warped product of an asymptotically AdS_4 space with ... More
Nonperturbative Dynamical Theory and A Scheme for Nonequilibrium TransportJan 31 2007Aug 10 2007We develop a nonperturbative dynamical theory (NDT) that is useful for treating nonequilibrium transport in a system with strong correlation. We apply our NDT to the single-impurity Anderson model in equilibrium to check its reliability by comparing with ... More
Hyers-Ulam stability of loxodromic Möbius difference equationAug 28 2018Hyers-Ulam of the sequence $ \{z_n\}_{n \in \mathbb{N}} $ satisfying the difference equation $ z_{i+1} = g(z_i) $ where $ g(z) = \frac{az + b}{cz + d} $ with complex numbers $ a $, $ b $, $ c $ and $ d $ is defined. Let $ g $ be loxodromic M\"obius map, ... More
Invariant space under Hénon renormalization : Intrinsic geometry of Cantor attractorAug 20 2014Jun 23 2015Three dimensional H\'non-like map $$ F(x,y,z) = (f(x) - \epsilon (x,y,z),\ x,\ \delta (x,y,z)) $$ is defined on the cubic box $ B $. An invariant space under renormalization would appear only in higher dimension. Consider renormalizable maps each of which ... More
MgII Line Variability of High Luminosity QuasarsFeb 25 2008Apr 02 2008We monitored five high-luminosity quasars with lambda L_{3000A} > 10^45 erg s^-1 at 0.4 < z < 0.6 to measure flux variability of the MgII 2798 line and explore feasibility of reverberation mapping using MgII. Over the two year monitoring program, imaging ... More
Multiple Stellar Populations of Globular Clusters from Homogeneous Ca--CN--CH Photometry. V. $cn^\prime_{\rm JWL}$ as a Surrogate $cn_{\rm JWL}$ Index and NGC 6723Aug 19 2019We introduce new color indices $cn^\prime_{\rm JWL}$ (= $Ca_{\rm CTIO} - Ca_{\rm JWL}$) and $ch_{\rm JWL}$ [=$(JWL43 - b) - (b-y)$], accurate photometric measures of the CN band at $\lambda$3883 and the CH G band, respectively, in the study of the multiple ... More
Analytical Gradient Theory for Strongly Contracted (SC-) and Partially Contracted (PC-) N-Electron Valence State Perturbation Theory (NEVPT2)Jul 24 2019Sep 01 2019An analytical gradient theory for single-state N-electron valence state perturbation theory (NEVPT2), using both strongly contracted (SC) and partially contracted (PC) internal contraction schemes, is developed. We demonstrate the utility of the developed ... More
Fused Trees: Simple BST balancing method by partial & scheduled rebuildsSep 01 2017This paper proposes a simple method to balance a binary search tree, as an attempt to develop the simplest and most explicit procedure. For a given constant $k$ in (0, 0.5), a rebuilt subtree of size $n$ rebuilds itself again after $\max(1,\left\lfloor ... More
Are There Any New Vacua of Gauged N=8 Supergravity in Four Dimensions?Apr 14 2009Dec 23 2009We consider the most general SU(3) singlet space of gauged N=8 supergravity in four-dimensions. The SU(3)-invariant six scalar fields in the theory can be viewed in terms of six real four-forms. By exponentiating these four-forms, we eventually obtain ... More
NtMalDetect: A Machine Learning Approach to Malware Detection Using Native API System CallsFeb 15 2018May 19 2018As computing systems become increasingly advanced and as users increasingly engage themselves in technology, security has never been a greater concern. In malware detection, static analysis, the method of analyzing potentially malicious files, has been ... More
Multiple stellar populations of globular clusters from homogeneous Ca--CN photometry. III. NGC 6752Jan 29 2019Jan 30 2019We present a multiple stellar population (MSP) study of the globular cluster (GC) NGC~6752. We show that our new photometric CN index accurately traces the CN and the nitrogen abundances in cool giants, finding the discrete double red giant branch (RGB) ... More
A Simple Balanced Search Tree with No Balance CriterionSep 01 2017Aug 07 2019We present a method that maintains a balanced binary search tree without using any tree balance criterion at all, with the ultimate aim of maximum simplicity. In fact, our method is highly intuitive, and we only need to add minimal extra code and a simple ... More
When is a Schubert variety Gorenstein?Sep 25 2004Nov 21 2005A (normal) variety is Gorenstein if it is Cohen-Macualay and its canonical sheaf is a line bundle. This property, which measures the ``pathology'' of the singularities of a variety, is thus stronger than Cohen-Macualayness, but is also weaker than smoothness. ... More
Current-driven dynamics and inhibition of the skyrmion Hall effect of ferrimagnetic skyrmions in GdFeCo filmsMar 30 2017Jan 30 2018Magnetic skyrmions are swirling magnetic textures with novel characteristics suitable for future spintronic and topological applications. Recent studies confirmed the room-temperature stabilization of skyrmions in ultrathin ferromagnets. However, such ... More
Efficient geometric integrators for nonadiabatic quantum dynamics. II. The diabatic representationMar 12 2019May 10 2019Exact nonadiabatic quantum evolution preserves many geometric properties of the molecular Hilbert space. In a companion paper [S. Choi and J. Van\'{\i}\v{c}ek, 2019], we presented numerical integrators of arbitrary-order of accuracy that preserve these ... More
An Energy-Efficient FPGA-based Deconvolutional Neural Networks Accelerator for Single Image Super-ResolutionJan 18 2018Dec 18 2018Convolutional neural networks (CNNs) demonstrate excellent performance in various computer vision applications. In recent years, FPGA-based CNN accelerators have been proposed for optimizing performance and power efficiency. Most accelerators are designed ... More
Poisson's Ratio of Layered Two-dimensional CrystalsJul 27 2015We present first-principles calculations of elastic properties of multilayered two-dimensional crystals such as graphene, h-BN and 2H-MoS2 which shows that their Poisson's ratios along out-of-plane direction are negative, near zero and positive, respectively, ... More
AI4AI: Quantitative Methods for Classifying Host Species from Avian Influenza DNA SequenceFeb 26 2018Avian Influenza breakouts cause millions of dollars in damage each year globally, especially in Asian countries such as China and South Korea. The impact magnitude of a breakout directly correlates to time required to fully understand the influenza virus, ... More
Multi-hop Data Fragmentation in Unattended Wireless Sensor NetworksJan 17 2019In this work, we analyze the advantages of multi-hop data fragmentation in unattended wireless sensor networks (UWSN) and propose a lightweight protocol to achieve it. UWSN has recently become an important aspect in various areas of sensor networks where ... More
X-ray Scaling Relation in Early-Type Galaxies: Dark Matter as a Primary Factor in Retaining Hot GasApr 23 2013Aug 27 2013We have revisited the X-ray scaling relations of early type galaxies (ETG) by investigating, for the first time, the LX,Gas - MTotal relation in a sample of 14 ETGs. In contrast to the large scatter (by a factor of 102-103) in the LX,Total - LB relation, ... More
X-ray Properties of Young Early Type Galaxies: I. X-ray Luminosity Function of LMXBsApr 14 2010Aug 05 2010We have compared the combined X-ray luminosity function (XLF) of LMXBs detected in Chandra observations of young, post-merger elliptical galaxies, with that of typical old elliptical galaxies. We find that the XLF of the 'young' sample does not present ... More
Chandra X-ray Observations of NGC 1316 (Fornax A)Jun 20 2002Dec 23 2002We report the results of the Chandra ACIS sub-arcsecond resolution X-ray observation of the archetypal merger radio galaxy NGC 1316 (Fornax A). We confirm the presence of fine sub-structures in the hot Interstellar Medium (ISM). Some of these are likely ... More
Two Growing Modes Lead to the Morphology-Quiescence Relation in GalaxiesOct 29 2018Quiescence in galaxies correlates strongly with the central density/morphology of the stellar distribution. We investigate two possible explanations for this morphology-quiescence relation: 1) the central density results from a dissipative core-building ... More
Intrinsic spin-orbit torque in an antiferromagnet with a weakly noncollinear spin configurationMar 16 2018Apr 03 2018An antiferromagnet is a promising material for spin-orbit torque generation. Earlier studies of the spin-orbit torque in an antiferromagnet are limited to collinear spin configurations. We calculate the spin-orbit torque in an antiferromagnet whose spin ... More
Adaptive Weight Decay for Deep Neural NetworksJul 21 2019Aug 07 2019Regularization in the optimization of deep neural networks is often critical to avoid undesirable over-fitting leading to better generalization of model. One of the most popular regularization algorithms is to impose L-2 penalty on the model parameters ... More
Quantification of Macroscopic Quantum Superpositions within Phase SpaceJan 06 2011May 11 2011Based on phase-space structures of quantum states, we propose a novel measure to quantify macroscopic quantum superpositions. Our measure simultaneously quantifies two different kinds of essential information for a given quantum state in a harmonious ... More
Effects of squeezing on quantum nonlocality of superpositions of coherent statesOct 21 2009We analyze effects of squeezing upon superpositions of coherent states (SCSs) and entangled coherent states (ECSs) for Bell-inequality tests. We find that external squeezing can always increase the degrees of Bell violations, if the squeezing direction ... More
Exploring the relationship between technological improvement and innovation diffusion: An empirical testApr 12 2017May 31 2018Different technological domains have significantly different rates of performance improvement. Prior theory indicates that such differing rates should influence the relative speed of diffusion of the products embodying the different technologies since ... More
A Note on Preconditioning by Low-Stretch Spanning TreesMar 16 2009Boman and Hendrickson observed that one can solve linear systems in Laplacian matrices in time $\bigO{m^{3/2 + o (1)} \ln (1/\epsilon)}$ by preconditioning with the Laplacian of a low-stretch spanning tree. By examining the distribution of eigenvalues ... More
Analytical derivative coupling for multistate CASPT2 theoryJan 09 2017May 03 2017The probability of non-radiative transitions in photochemical dynamics is determined by the derivative couplings, the couplings between different electronic states through the nuclear degrees of freedom. Efficient and accurate evaluation of the derivative ... More
One-loop Gauge Couplings in Orbifold Field TheoriesNov 30 2003Jan 04 2004We discuss the gauge coupling renormalization in orbifold field theories in which the 4-dimensional graviton and/or matter fields are quasi-localized in extra dimension to generate hierarchically different mass scales and/or Yukawa couplings. In such ... More
Two Growing Modes and the Morphology-Quiescence Relation in GalaxiesOct 29 2018May 15 2019Quiescence in galaxies correlates strongly with the central density/morphology of the stellar distribution. We investigate two possible explanations for this morphology-quiescence relation: 1) the central density results from a dissipative core-building ... More
On the cohomology of compact unitary group Shimura varieties at ramified split placesOct 02 2011In this article, we prove results about the cohomology of compact unitary group Shimura varieties at split places. In nonendoscopic cases, we are able to give a full description of the cohomology, after restricting to integral Hecke operators at p on ... More
A System Dynamics Analysis of National R&D Performance Measurement System in KoreaJan 16 2019Peer review is one of useful and powerful performance measurement process. In Korea, it needs to increase quality of R&D performance, but bibliometric evaluation and lack of peers have opposite effect. We used system dynamics to describe Korean R&D performance ... More
Bell-state measurement and quantum teleportation using linear optics: two-photon pairs, entangled coherent states, and hybrid entanglementApr 04 2013We review and compare Bell-state measurement and quantum teleportation schemes using linear optics with three different types of resources, i.e., two-photon pairs, entangled coherent states and hybrid entangled states. Remarkably, perfect teleportation ... More
Moiré phonons in the twisted bilayer grapheneMay 23 2019Aug 16 2019We study the in-plane acoustic phonons in twisted bilayer graphenes using the effective continuum approach. We calculate the phonon modes by solving the continuum equation of motion for infinitesimal vibration around the static relaxed state with triangular ... More
Sato-Tate theorem for families and low-lying zeros of automorphic $L$-functionsAug 09 2012Nov 15 2014We consider certain families of automorphic representations over number fields arising from the principle of functoriality of Langlands. Let $G$ be a reductive group over a number field $F$ which admits discrete series representations at infinity. Let ... More
Endoscopy and cohomology of U(n,1)Apr 13 2018By assuming the endoscopic classification of automorphic representations on inner forms of unitary groups, which is currently work in progress by Kaletha, Minguez, Shin, and White, we bound the growth of cohomology in congruence towers of locally symmetric ... More
Phantom elements and its ApplicationsJun 29 2001In our previous work, a relation between Tsukiyama problem about self homotopy equivalence was found by using a generalization of phantom map. In this note, fundamental result is established for such a generalization. This is the first time one can deal ... More
A census of ionized gas outflows in type 1 AGNs: gas outflows in AGNs. VAug 10 2018We present a systematic study of ionized gas outflows based on the velocity shift and dispersion of the [O III] {\lambda}5007 $\AA$ emission line, using a sample of ~ 5000 Type 1 AGNs at z < 0.3 selected from Sloan Digital Sky Survey. This analysis is ... More
Far-infrared and accretion luminosities of the present-day active galactic nucleiMay 21 2015We investigate the relation between star formation (SF) and black hole accretion luminosities, using a sample of 492 type-2 active galactic nuclei (AGNs) at z < 0.22, which are detected in the far-infrared (FIR) surveys with AKARI and Herschel. We adopt ... More
One loop gauge couplings in AdS5Aug 09 2002Jan 10 2004We calculate the full 1-loop corrections to the low energy coupling of bulk gauge boson in a slice of AdS5 which are induced by generic 5-dimensional scalar, Dirac fermion, and vector fields with arbitrary Z_2 times Z_2' orbifold boundary conditions. ... More
Costly bilingualism model in a population with one zealotJul 17 2013We consider a costly bilingualism model in which one can take two strategies in parallel. We investigate how a single zealot triggers the cascading behavior and how the compatibility of the two strategies affects when interacting patterns change. First, ... More