• Computers and Concrete
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• 제13권4호
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• pp.483-499
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• 2014

Most of the methods presented in the literature to define the target service stresses (Objective Service Stage, OSS) of cable-stayed bridges rarely include the time-dependent phenomena effects. Nevertheless, especially in concrete structures, this assumption might be on the unsafe side because time-dependent phenomena usually modify service stresses. To fill this gap, this paper studies the time-dependent phenomena effects into service stresses of concrete cable-stayed bridges. After illustrating the important role of these phenomena in an asymmetrical cable-stayed bridge without backstay, a new method to include their effects into the OSS is presented. An important issue to be considered in this method is the target time in which the OSS is defined to be achieved. The application of this method to two different structures showed the convenience of defining the OSS to be achieved at early times because that way the envelope of service stresses is reduced.

• 충청수학회지
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• 제31권3호
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• pp.287-308
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• 2018

This paper deals with blow-up phenomena for an initial boundary value problem of a quasilinear parabolic equation with time-dependent coefficient in a bounded star-shaped region under nonlinear boundary flux. Using the auxiliary function method and differential inequality technique, we establish some conditions on time-dependent coefficient and nonlinear functions for which the solution u(x, t) exists globally or blows up at some finite time $t^*$. Moreover, some upper and lower bounds for $t^*$ are derived in higher dimensional spaces. Some examples are presented to illustrate applications of our results.

• 새물리
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• 제68권11호
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• pp.1225-1230
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• 2018

Schwinger pair production of electrons and positrons in a strong electric field is a prediction of nonperturbative quantum field theory, in which the out-vacuum is superposed of multi-particle states of the in-vacuum. Solving the Dirac or Klein-Gordon equation in the background field, though a linear wave equation, and finding the pair-production rate is a difficult or nontrivial job. The phase-integral method has recently been introduced to compute the pair production in space-dependent electric fields, and a complex analysis method has been employed to calculate the pair production in time-dependent electric fields. In this paper, we apply the complex analysis method to a Sauter-type electric field and other hyperbolic-type electric fields that vanish in the past and future and show that the Stokes phenomena in pair production occur when the time-dependent frequency for a given momentum has finite simple poles (polons) with pure imaginary residues.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.250-251
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• 2014

This paper investigates the stick-slip phenomena on spinning shaft. The modeling of the shaft is considered only torsional direction with nonlinear friction. The friction is adopted a negative friction-velocity slope. Based on the model, a nonlinear equation of motion is derived and analyze the stick-slip phenomena. In order to analyze the time dependent response, the nonlinear formulations are numerically solved by nonlinear Newmark method. The numerical results reveal the stick-slip phenomena on the spinning shaft system.

• Management Science and Financial Engineering
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• 제4권2호
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• pp.1-13
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• 1998

The Shortest Path Problem in Time-dependent Networks, where the travel time of each link depends on the time interval, is not realistic since the model and its solution violate the Non-passing Property (NPP:often referred to as FIFO) of real phenomena. Furthermore, solving the problem needs much more computational and memory complexity than the general shortest path problem. A new model for Time-dependent Networks where the flow speeds of each link depend on time interval, is suggested. The model is more realistic since its solution maintains the NPP. Solving the problem needs just a little more computational complexity, and the same memory complexity, as the general shortest path problem. A solution algorithm modified from Dijkstra's label setting algorithm is presented. We extend this model to the problem of Minimum Expected Time Path in Time-dependent Stochastic Networks where flow speeds of each link change statistically on each time interval. A solution method using the Kth-shortest Path algorithm is presented.

• 호남수학학술지
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• 제43권4호
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• pp.667-678
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• 2021

Blow-up phenomena for a nonlocal reaction-diffusion system with time-dependent coefficients are investigated under null Dirichlet boundary conditions. Using Kaplan's method with the comparison principle, we establish new blow-up criteria and obtain the upper bounds for the blow-up time of the solution under suitable measure sense in the whole-dimensional space.

• Structural Engineering and Mechanics
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• 제61권3호
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• pp.317-323
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• 2017

This work presents a new strategy to model stress dependent relaxation process in large deformation. The strategy is relied on the fact that in some particular soft materials undergoing large deformation, e.g., elastomers, rubbers and soft tissues, the relaxation time depends strongly on stress levels. To simplify the viscoelastic model, we consider that the relaxation time is the function of previous elastic deviatoric stress state experienced by materials during loading. Using the General Maxwell Model (GMM), we simulate numerically conditions with the constant and the stress dependent relaxation time for uniaxial tension and compression loading. Hence, it can be shown that the proposed model herein not only can represent different relaxation time for different stress level but also maintain the capability of the GMM to model hysteresis phenomena.

• 대한수학회논문집
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• 제23권1호
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• pp.67-80
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• 2008

Feynman's operational calculus for noncommuting operators was studied via measures on the time interval. We investigate some properties of Feynman's operational calculi which include a variety of blends of discrete and continuous measures in the time dependent setting.

• 한국멀티미디어학회논문지
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• 제24권3호
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• pp.468-480
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• 2021

Realistic real-time rain streaks rendering has been treated as a very difficult problem because of various natural phenomena. Also, in creating and managing a large number of particles, a large amount of computer resources had to be used. Therefore, in this paper, we propose a more efficient real-time rain streaks rendering algorithm by generating view-dependent rain particles and expressing a large amount of rain even with a small number. By creating a 'rain space' dependent on the field of view of the camera moving in real time, particles are rendered only in that space. Accordingly, even if a small number of particles are rendered, since the rendering is performed in a limited space, an effect of rendering a very large amount of particles can be obtained. This enables very efficient real-time rendering of rain streaks.

• 대한전자공학회논문지
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• 제26권10호
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• pp.1571-1575
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• 1989

Nonlinear beam coupling phenomena in photorefractive materials are analyzed as a function of the input beam intensities. Signal beam saturation and pump beam depletion are shown to be the intensity-dependent functions of these materials. Utilizing these phenomena in a photorefractive BaTiO3 crystal, optical logic processors such as AND, OR, NOT, etc., are implemented.