• Title, Summary, Keyword: parametric gap function

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ON THE LOWER SEMICONTINUITY OF THE SOLUTION SETS FOR PARAMETRIC GENERALIZED VECTOR MIXED QUASIVARIATIONAL INEQUALITY PROBLEMS

  • HUNG, NGUYEN VAN
    • Bulletin of the Korean Mathematical Society
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    • v.52 no.6
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    • pp.1777-1795
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    • 2015
  • In this paper, we establish sufficient conditions for the solution set of parametric generalized vector mixed quasivariational inequality problem to have the semicontinuities such as the inner-openness, lower semicontinuity and Hausdorff lower semicontinuity. Moreover, a key assumption is introduced by virtue of a parametric gap function by using a nonlinear scalarization function. Then, by using the key assumption, we establish condition ($H_h$(${\gamma}_0$, ${\lambda}_0$, ${\mu}_0$)) is a sufficient and necessary condition for the Hausdorff lower semicontinuity, continuity and Hausdorff continuity of the solution set for this problem in Hausdorff topological vector spaces with the objective space being infinite dimensional. The results presented in this paper are different and extend from some main results in the literature.

Optical and Electrical Properties of Sn-doped ZnO Thin Films Studied via Spectroscopic Ellipsometry and Hall Effect Measurements

  • So, Hyeon Seob;Hwang, Sang Bin;Jung, Dae Ho;Lee, Hosun
    • Journal of the Korean Physical Society
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    • v.70 no.7
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    • pp.706-713
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    • 2017
  • We investigated the optical and the electrical properties of Sn-doped ZnO thin films grown via RF co-sputtering deposition methods at room temperature. Through annealing, the carrier concentrations and mobilities were improved. The ellipsometric angles, ${\Psi}$ and ${\Delta}$, of the ZnO:Sn thin films were measured via spectroscopic ellipsometry. Dielectric functions were obtained from the ellipsometric angles by using the Drude and the parametric optical constant models. With an increase in the Sn doping concentration, the Drude model amplitude increased substantially. The Urbach and the optical gap energies of the ZnO:Sn films were determined using the dielectric functions. The carrier concentrations and the mobilities of the ZnO:Sn thin films were measured using Hall-effect measurements. The effective mass of ZnO:Sn was estimated to be $0.274m_0$, assuming that the carrier concentrations measured via ellipsometry and Hall-effect measurements were the same. A shift in the optical gap energy of the Sn-doped ZnO was found to be due to a combination of the Burstein-Moss effect, electron-electron interactions, and electron-impurity scattering. The discrepancy between the measured and the calculated shifts in the optical gap energy is attributed to Sn-alloying effects.

Estimating the Transmittable Prevalence of Infectious Diseases Using a Back-Calculation Approach

  • Lee, Youngsaeng;Jang, Hyun Gap;Kim, Tae Yoon;Park, Jeong-Soo
    • Communications for Statistical Applications and Methods
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    • v.21 no.6
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    • pp.487-500
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    • 2014
  • A new method to calculate the transmittable prevalence of an epidemic disease is proposed based on a back-calculation formula. We calculated the probabilities of reactivation and of parasitemia as well as transmittable prevalence (the number of persons with parasitemia in the incubation period) of malaria in South Korea using incidence of 12 years(2001-2012). For this computation, a new probability function of transmittable condition is obtained. The probability of reactivation is estimated by the least squares method for the back-calculated longterm incubation period. The probability of parasitemia is calculated by a convolution of the survival function of the short-term incubation function and the probability of reactivation. Transmittable prevalence is computed by a convolution of the infected numbers and the probabilities of transmission. Confidence intervals are calculated using the parametric bootstrap method. The method proposed is applicable to other epidemic diseases in other countries where incidence and a long incubation period are available. We found the estimated transmittable prevalence in South Korea was concentrated in the summer with 276 cases on a peak at the $31^{st}$ week and with about a 60% reduction in the peak from the naive prevalence. The statistics of transmittable prevalence can be used for malaria prevention programs and to select blood transfusion donors.

Parametric study of porous media as substitutes for flow-diverter stent

  • Ohta, Makoto;Anzai, Hitomi;Miura, Yukihisa;Nakayama, Toshio
    • Biomaterials and Biomechanics in Bioengineering
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    • v.2 no.2
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    • pp.111-125
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    • 2015
  • For engineers, generating a mesh in porous media (PMs) sometimes represents a smaller computational load than generating realistic stent geometries with computer fluid dynamics (CFD). For this reason, PMs have recently become attractive to mimic flow-diverter stents (FDs), which are used to treat intracranial aneurysms. PMs function by introducing a hydraulic resistance using Darcy's law; therefore, the pressure drop may be computed by test sections parallel and perpendicular to the main flow direction. However, in previous studies, the pressure drop parallel to the flow may have depended on the width of the gap between the stent and the wall of the test section. Furthermore, the influence of parameters such as the test section geometry and the distance over which the pressure drops was not clear. Given these problems, computing the pressure drop parallel to the flow becomes extremely difficult. The aim of the present study is to resolve this lack of information for stent modeling using PM and to compute the pressure drop using several methods to estimate the influence of the relevant parameters. To determine the pressure drop as a function of distance, an FD was placed parallel and perpendicular to the flow in test sections with rectangular geometries. The inclined angle method was employed to extrapolate the flow patterns in the parallel direction. A similar approach was applied with a cylindrical geometry to estimate loss due to pipe friction. Additionally, the pressure drops were computed by using CFD. To determine if the balance of pressure drops (parallel vs perpendicular) affects flow patterns, we calculated the flow patterns for an ideal aneurysm using PMs with various ratios of parallel pressure drop to perpendicular pressure drop. The results show that pressure drop in the parallel direction depends on test section. The PM thickness and the ratio of parallel permeability to perpendicular permeability affect the flow pattern in an ideal aneurysm. Based on the permeability ratio and the flow patterns, the pressure drop in the parallel direction can be determined.

A Numerical and Experimental Study for Fry-drying of Various Sludge (슬러지 유중 건조에 대한 전산 해석 및 실험적 연구)

  • Shin, Mi-Soo;Kim, Hey-Suk;Kim, Byeong-Gap;Hwang, Min-Jeong;Jang, Dong-Soon;Ohm, Tae-In
    • Journal of Korean Society of Environmental Engineers
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    • v.32 no.4
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    • pp.341-348
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    • 2010
  • The basic principle of fry drying process of sludge lies in the rapid pressure change of sludge material caused by the change of temperature between oil and moisture due to the difference of specific heat. Therefore, the rapid increase of pressure in drying sludge induces the efficient moisture escape through sludge pores toward heating oil media. The object of this study is to carry out a systematic investigation of the influence of various parameters associated with the sludge fry drying processes on the drying efficiency. To this end, a series of parametric experimental investigation has been made together with the numerical calculation in order to obtain typical drying curves as function of important parameters such as drying temperature, sludge diameter, oil type and sludge type. In the aspect of frying temperature, especially it is found that the operation higher than $140^{\circ}C$ was favorable in drying efficiency regardless of type of waste oil employed in this study. The same result was also noted consistently in the investigation of numerical calculation, that is, in that the sludge particle drying was efficiently made over $140^{\circ}C$ irrespective of the change of particle diameter. As expected, in general, the decrease of diameter in sludge was found efficient both experiment and numerical calculation in drying due to the increased surface area per unit volume. In the investigation of oil type and property, the effect of the viscosity of waste oil was found to be more influential in drying performance. In particular, when the oil with high viscosity, a visible time delay was noticed in moisture evaporation especially in the early stage of drying. However, the effect of high viscosity decreased significantly over the temperature of $140^{\circ}C$. There was no visible difference observed in the study of sludge type but the sewage sludge with a slightly better efficiency. The numerical study is considered to be a quite useful tool to assist in experiment with more detailed empirical modeling as further work.