• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.529-546
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• 2011

A deterministic tuberculosis model for theoretically assessing the potential impact of the combined effects of case detection in the presence of treatment is formulated. The qualitative features of its equilibria are analyzed and it is found that the disease-free equilibrium may not be globally asymptotically stable when the reproduction number is less than unity. This disease threshold number is further used to assess the impact of active TB case finding alone and in conjunction with treatment. A critical threshold parameter ${\Theta}$ say for which case detection will have a positive impact is derived. Using the Centre Manifold theory, the model may exhibit the phenomenon of backward bifurcation (coexistence of a locally stable endemic equilibrium with a stable disease-free equilibrium) when the reproduction number is less than unity. It is shown that the possibility of backward bifurcation occurring decreases with increase case detection. Graphical representations suggest that increase in case finding accompanied by treatment of detected TB cases, result in a marked decrease of TB cases (both latent and active TB).

• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.731-770
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• 1997

We study Diriclet forms and related subjects for the Gibbs measures of classical unbounded sping systems interacting via potentials which are superstable and regular. For any Gibbs measure $\mu$, we construct a Dirichlet form and the associated diffusion process on $L^2(\Omega, d\mu), where \Omega = (R^d)^Z^\nu$. Under appropriate conditions on the potential we show that the Dirichlet operator associated to a Gibbs measure $\mu$ is essentially self-adjoint on the space of smooth bounded cylinder functions. Under the condition of uniform log-concavity, the Gibbs measure exists uniquely and there exists a mass gap in the lower end of the spectrum of the Dirichlet operator. We also show that under the condition of uniform log-concavity, the unique Gibbs measure satisfies the log-Sobolev inequality. We utilize the general scheme of the previous works on the theory in infinite dimensional spaces developed by e.g., Albeverio, Antonjuk, Hoegh-Krohn, Kondratiev, Rockner, and Kusuoka, etc, and also use the equilibrium condition and the regularity of Gibbs measures extensively.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.73-73
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• 2003

We report here the results on N-acetyl-N'-methylamide of alanine (Ac-Ala-NHMe) calculated using the ab initio molecular orbital method with the self-consistent reaction field (SCRF) theory at the HF level with the 6-3l+G(d) basis set to investigate the conformational preference of alanine depending on the backbone torsion angles $\square$ and$\square$ in the gas phase, chloroform, and water. There are seven local minima (LM) in the gas phase and two additional LM are found in chloroform and water. These two additional LM A (an $\square$-helical structure) and F (a polyproline structure) are stabilized only in solutions. In the gas phase, the lowest LM is the conformation C with a C$\sub$7/ intramolecular hydrogen bond and the relative conformational energies range from 0.3 to 6.0 ㎉/mol. In chloroform, the lowest LM is the conformation E (an extended structure) and the relative conformational energies range from 0.7 to 4.9 ㎉/mol. In particular, we identified 14 possible transition states connecting between seven LM in the gas phase. The search for transition states probable in chloroform and water is now in progress.

• Earthquakes and Structures
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• v.3 no.5
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• pp.767-781
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• 2012

The residual capacity against collapse of a main shock-damaged bridge can be coupled with the aftershock ground motion hazard to make an objective decision on its probability of collapse in aftershocks. In this paper, a steel tower suspension bridge with a main span of 2000 m is adopted for a case-study. Seismic responses of the bridge in longitudinal and transversal directions are analyzed using dynamic elasto-plastic finite displacement theory. The analysis is conducted in two stages: main shock and aftershocks. The ability of the main shock-damaged bridge to resist aftershocks is discussed. Results show that the damage caused by accumulated plastic strain can be ignored in the long-span suspension bridge. And under longitudinal and transversal seismic excitations, the damage is prone to occur at higher positions of the tower and the shaft-beam junctions. When aftershocks are not large enough to cause plastic strain in the structure, the aftershock excitation can be ignored in the seismic damage analysis of the bridge. It is also found that the assessment of seismic damage can be determined by superposition of damage under independent action of seismic excitations.

• Current Optics and Photonics
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• v.8 no.1
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• pp.97-104
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• 2024

In aerial cameras, image quality is easily affected by weather, temperature, and the attitude of the aircraft. Aiming at this phenomenon, based on the theory of two-step zoom optical systems, a dual-band optical-despun two-step zoom optical system is designed. The system has a small field of view of 2.00° × 1.60°, and a large field of view of 4.00° × 3.20°. In the zoom process, the wavelength range is 0.45-0.70 ㎛ and 0.75-1.10 ㎛, and the size of the optical system is 168 mm (L) × 90 mm (W) × 60 mm (H). The overall lens weight is only 170.8 g, which has advantages for miniaturization and light weight. At the Nyquist frequency of 104 lp/mm, the modulation transfer function of the visible-light optical system is more than 0.44, and that of the near-infrared optical system is more than 0.30, both of which have good imaging quality and tolerance characteristics in the range of -45 to 60 ℃.

• Structural Engineering and Mechanics
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• v.92 no.2
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• pp.163-172
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• 2024

This paper intends to analyze the nonlinear forced vibrations of functionally graded material (FGM) beams with initial geometrical defects in hygro-thermal ambiences. For this purpose, we assume that the correlation properties of the material alter along the thickness direction in succession and the surface of the beam is subjected to humid and thermal loads. Based on the Euler Bernoulli beam theory and geometrical non-linearity, we use the Hamiltonian principle to formulate a theoretical model with consideration of the hygrothermal effects. Galerkin's technique has been proposed for the control equations of discrete systems. The non-linear primary resonances are acquired by applying the modified Lindstedt-Poincare method (MLP). Verify the reliability of the data obtained through comparison with literature. The non-linear resonance response is reflected by amplitude-frequency response curves. The numerical results indicate that the resonances of FGM beams include three non-linear characteristics, namely hard springs, soft springs and soft-hard spring types. The response modalities of the structure may transform between those non-linear characteristics when material properties, spring coefficients, geometric defect values, temperature-humidity loads and even the external stimulus generate variations.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.2
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• pp.85-94
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• 2005

It has been reported and verified in many design experiences that a judicious utilization of the page and burst access modes supported by DRAMs contributes a great reduction in not only the DRAM access latency but also DRAM's energy consumption. Recently, researchers showed that a careful arrangement of data variables in memory directly leads to a maximum utilization of the page and burst access modes for the variable accesses, but unfortunately, found that the problems are not tractable, consequently, resorting to simple (e.g., greedy) heuristic solutions to the problems. In this parer, to improve the quality of existing solutions, we propose 0-1 ILP-based techniques which produce optimal or near-optimal solution depending on the formulation parameters. It is shown that the proposed techniques use on average 32.2%, l5.1% and 3.5% more page accesses, and 84.0%, 113.5% and 10.1% more burst accesses compared to OFU (the order of first use) and the technique in [l, 2] and the technique in [3], respectively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.23-36
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• 1990

The various composite materials have been developed with the development of high strength material and the increasement of composite material usage. Therefore many researchers have studied about the stress analysis and the fracture mechanics for composite materials through the experiment or the theory. Among the experimental methods, the photoelastic experiments have been used for the stress analysis of the isotropic structures or the anisotropic structures. To analyze the stresses in the orthotropic material with photoelastic experiment, the basic physical properties ( $E_{L}$, $E_{T}$, $G_{LT}$ , .nu.$_{LT}$ ) and the basic stress fringe values ( $f_{L}$, $f_{T}$, $f_{LT}$ )are needed, therefore the relationships between the basic physical properties and the stress fringe values were derived in this paper. When the stress fringe value is very large, it was assured by the experiment that the relationships are established both in the room temperature and in the high temperature (T = 130.deg. C). Therefore the basic physical properties can be obtained from the relationships by measuring stress fringe values instead of measuring the basic physical properties.rties.

• Wind and Structures
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• v.19 no.3
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• pp.339-352
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• 2014

This paper discusses the appropriate duration for basic gust wind speeds in wind loading codes and standards, and in wind engineering generally. Although various proposed definitions are discussed, the 'moving average' gust duration has been widely accepted internationally. The commonly-specified gust duration of 3-seconds, however, is shown to have a significant effect on the high-frequency end of the spectrum of turbulence, and may not be ideally suited for wind engineering purposes. The effective gust durations measured by commonly-used anemometer types are discussed; these are typically considerably shorter than the 'standard' duration of 3 seconds. Using stationary random process theory, the paper gives expected peak factors, $g_u$, as a function of the non-dimensional parameter ($T/{\tau}$), where T is the sample, or reference, time, and ${\tau}$ is the gust duration, and a non-dimensional mean wind speed, $\bar{U}.T/L_u$, where $\bar{U}$ is a mean wind speed, and $L_u$ is the integral length scale of turbulence. The commonly-used Durst relationship, relating gusts of various durations, is shown to correspond to a particular value of turbulence intensity $I_u$, of 16.5%, and is therefore applicable to particular terrain and height situations, and hence should not be applied universally. The effective frontal areas associated with peak gusts of various durations are discussed; this indicates that a gust of 3 seconds has an equivalent frontal area equal to that of a tall building. Finally a generalized gust response factor format, accounting for fluctuating and resonant along-wind loading of structures, applicable to any code is presented.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1559-1571
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• 2008

A rule was developed to constrain the annual rate of inbreeding to a predefined value in a population with different lifetimes between sires and dams, and to maximize the selection response over generations. This rule considers that the animals in a population should be divided into sex-age classes based on the theory of gene flow, and restricts the increase of average inbreeding coefficient for new offspring by limiting the increase of the mean additive genetic relationship for parents selected. The optimization problem of this rule was formulated as a quadratic programming problem. Inputs for the rule were the BLUP estimated breeding values, the additive genetic relationship matrix of all animals, and the long-term contributions of sex-age classes. Outputs were optimal number and contributions of selected animals. In addition, this rule was combined with the optimization of emphasis given to QTL, and further increased the genetic gain over the planning horizon. Stochastic simulations of closed nucleus schemes for pigs were used to investigate the potential advantages obtained from this rule by combining the standard QTL selection, optimal QTL selection and conventional BLUP selection. Results showed that the predefined rates of inbreeding were actually achieved by this rule in three selection strategies. The rule obtained up to 9.23% extra genetic gain over truncation selection at the same rates of inbreeding. The combination of the extended rule and the optimization of emphasis given to QTL allowed substantial increases in selection response at a fixed annual rate of inbreeding, and solved substantially the conflict between short-term and long-term selection response in QTL-assisted selection schemes.