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Search Results: 1 - 10 of 332648 matches for " K. C. Yeong "
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A Study on Similarity Computations in Template Matching Technique for Identity Verification
Lam, S. K.,,Yeong,,C. Y.,,Yew
International Journal on Computer Science and Engineering , 2010,
Abstract: This paper describes a study on the development of a human face verification system by merely using template matching (TM) as the main verification engine. In contrast to common face recognition techniques, our approach for the identity verification (face recognition) consists of matching the facial features extracted from the detected face. These facial features namely left eye, right eye and mouth regions; are detected using a system known as EMoTracker. As TM is sensitive to lighting, this study considered different type of lighting directions and similarity computation in TM. Three types of TM functions are evaluated in this paper: Sum of Squared Difference, Cross Correlation and Correlation Coefficient. In the experiments, YaleB Database is used. Based on the observation esults, using Correlation Coefficient is shown to be the most reliable similarity computation to handle different lighting conditions using TM.
Hadronic Invariant Mass Spectrum in B -> X_u l nu Decay with Lepton Energy Cut
K. K. Jeong,C. S. Kim,Yeong Gyun Kim
Physics , 2000, DOI: 10.1103/PhysRevD.63.014005
Abstract: We discuss the implications of charged lepton energy cut to the hadronic invariant mass spectrum in charmless semileptonic B decays. Charged-lepton energy cut is inevitable in order to remove secondary leptonic events such as b -> c, tau -> l, and to identify the chaged leptons at detectors experimentally. We consider three possible lepton energy cuts, E_l^{cuts} = 0.6,1.5,2.3 GeV, and found that with the most probable cuts E_l^{cut} = 1.5 GeV and M_X^{max} = 1.5~(1.86) GeV, 45 ~ 60 % ~(58 ~ 67 %) of decay events survive. Therefore, B -> X_u l nu decay events can be efficiently distinguished from B -> X_c l nu decay events. We also discuss the possible model dependence on the results.
Wave Propagation in Lossy and Superconducting Circular Waveguides
K. H. Yeap,C. Y. Tham,K. C. Yeong,H. J. Woo
Radioengineering , 2010,
Abstract: We present an accurate approach to compute the attenuation of waves, propagating in circular waveguides with lossy and superconducting walls. A set of transcendental equation is developed by matching the fields at the surface of the wall with the electrical properties of the wall material. The propagation constant kz is found by numerically solving for the root of the equation. The complex conductivity of the superconductor is obtained from the Mattis-Bardeen equations. We have compared the loss of TE11 mode computed using our technique with that using the perturbation and Stratton’s methods. The results from the three methods agree very well at a reasonable range of frequencies above the cutoff. The curves, however, deviate below cutoff and at millimeter wave frequencies. We attribute the discrepancies to the dispersive effect and the presence of the longitudinal fields in a lossy waveguide. At frequencies below the gap, the superconducting waveguide exhibits lossless transmission behavior. Above the gap frequency, Cooper-pair breaking becomes dominant and the loss increases significantly.
Attenuation in Rectangular Waveguides with Finite Conductivity Walls
K. H. Yeap,C. Y. Tham,G. Yassin,K. C. Yeong
Radioengineering , 2011,
Abstract: We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E) and the magnetic field (H) at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity ε, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion.
Mesoscopic Phase Coherence in a Quantum Spin Fluid
Guangyong Xu,C. Broholm,Yeong-Ah Soh,G. Aeppli,J. F. DiTusa,Ying Chen,M. Kenzelmann,C. D. Frost,T. Ito,K. Oka,H. Takagi
Physics , 2008, DOI: 10.1126/science.1143831
Abstract: Mesoscopic quantum phase coherence is important because it improves the prospects for handling quantum degrees of freedom in technology. Here we show that the development of such coherence can be monitored using magnetic neutron scattering from a one-dimensional spin chain Y2BaNiO5, a quantum spin fluid where no classical, static magnetic order is present. In the cleanest samples, the quantum coherence length is 20 nm, almost an order of magnitude larger than the classical antiferromagnetic correlation length of 3 nm. We also demonstrate that the coherence length can be modified by static and thermally activated defects in a quantitatively predictable manner.
$b \to s γ$ decays in the Left-Right Symmetric Model
C. S. Kim,Yeong Gyun Kim
Physics , 1999, DOI: 10.1103/PhysRevD.61.054008
Abstract: We consider $b \to s \gamma$ decays in the Left-Right Symmetric Model. Values of observables sensitive to chiral structure such as the $\Lambda$ polarization in the $\Lambda_b \to \Lambda \gamma$ decays and the mixing-induced CP asymmetries in the $B_{d,s} \to M^0 \gamma$ decays can deviate in the LRSM significantly from the SM values. The combined analysis of $P_\Lambda$ and $A_{CP}$ as well as ${\cal BR}(b \to s \gamma)$ can be used to determine the model parameters.
Better Bell Inequality Violation by Collective Measurements
Yeong-Cherng Liang,Andrew C. Doherty
Physics , 2006, DOI: 10.1103/PhysRevA.73.052116
Abstract: The standard Bell inequality experiments test for violation of local realism by repeatedly making local measurements on individual copies of an entangled quantum state. Here we investigate the possibility of increasing the violation of a Bell inequality by making collective measurements. We show that nonlocality of bipartite pure entangled states, quantified by their maximal violation of the Bell-Clauser-Horne inequality, can always be enhanced by collective measurements, even without communication between the parties. For mixed states we also show that collective measurements can increase the violation of Bell inequalities, although numerical evidence suggests that the phenomenon is not common as it is for pure states.
Bounds on Quantum Correlations in Bell Inequality Experiments
Yeong-Cherng Liang,Andrew C. Doherty
Physics , 2006, DOI: 10.1103/PhysRevA.75.042103
Abstract: Bell inequality violation is one of the most widely known manifestations of entanglement in quantum mechanics; indicating that experiments on physically separated quantum mechanical systems cannot be given a local realistic description. However, despite the importance of Bell inequalities, it is not known in general how to determine whether a given entangled state will violate a Bell inequality. This is because one can choose to make many different measurements on a quantum system to test any given Bell inequality and the optimization over measurements is a high-dimensional variational problem. In order to better understand this problem we present algorithms that provide, for a given quantum state, both a lower bound and an upper bound on the maximal expectation value of a Bell operator. Both bounds apply techniques from convex optimization and the methodology for creating upper bounds allows them to be systematically improved. In many cases these bounds determine measurements that would demonstrate violation of the Bell inequality or provide a bound that rules out the possibility of a violation. Examples are given to illustrate how these algorithms can be used to conclude definitively if some quantum states violate a given Bell inequality.
Stationary Vector Autoregressive Representation of Error Correction Models  [PDF]
Yun-Yeong Kim
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.22027
Abstract: The paper introduces a stationary vector autoregressive (VAR) representation of the error correction model (ECM). This representation explicitly regards the cointegration error a dependent variable, making the direct implementation of standard dynamic analyses using standard VAR models possible, particularly with respect to the cointegration error. Of course, an ECM does not have an explicit VAR form, and thus, it is not convenient for conducting such dynamic analyses. In this regard, we transform the original nonstationary VAR model into a VAR model with the cointegration error and stationary variables. Finally, we employ the model to dynamically analyze the real exchange rate between the US dollar and the Japanese yen.
Optimal Foreign Exchange Risk Hedging: A Mean Variance Portfolio Approach  [PDF]
Yun-Yeong Kim
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.31001
Abstract:


This paper introduces the optimal foreign exchange risk hedging model following a standard portfolio theory. The results indicate that a lower level of risk can be achieved, given a specified level of expected return, from using optimization modeling. In the paper the expected hedging return is defined from the expected cost of the foreign currency using a specified hedging strategy minus the expected cost of the foreign currency when it is purchased form the spot market. The focal point of the technique is its ability to identify optimal combinations of hedging vehicles, those are currency options, forward contracts, leaving the position open (foreign exchange risk hedging tools suggested by the US. Department of Commerce) in a closed form.


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