• 대한수학회보
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• 제49권2호
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• pp.307-317
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• 2012

We say (W, {${\phi}_1,\;{\ldots}\;,{\phi}_t$}) is a polarizable dynamical system of several morphisms if ${\phi}_i$ are endomorphisms on a projective variety W such that ${\otimes}{\phi}_i^*L$ is linearly equivalent to $L^{{\otimes}q}$ for some ample line bundle L on W and for some q > t. If q is a rational number, then we have the equidistribution of small points of given dynamical system because of Yuan's work [13]. As its application, we can build a polarizable dynamical system of an automorphism and its inverse on a K3 surface and can show that its periodic points are equidistributed.

• 대한수학회보
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• 제27권2호
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• pp.127-131
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• 1990

Let f:R.rarw.R be a continuous function on the real line R, and denote the n-th iterate of f by f$^{n}$ :f$^{1}$=f and f$^{n}$ =f.f$^{n-1}$ for n>1. A point x.mem.R is a periodic point of f of period k>0 if f$^{k}$ (x)=x but f$^{i}$ (x).neq.x for all 01, then it must also have a fixed point, by the intermediate Theorem. Also the question has an intriguing answer which was found by ths Russian mathematician Sharkovky [6] in 1964.

• Wind and Structures
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• 제5권2_3_4호
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• pp.141-150
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• 2002

Numerical simulations based on the ALE finite element method are carried out to examine the aerodynamics of an oscillating circular cylinder when the separated shear flows around the cylinder are stimulated by periodic jet excitation with a shear layer instability frequency. The excitation is applied to the flows from two points on the cylinder surface. The numerical results showed that the excitation with a shear layer instability frequency can reduce the negative damping and thereby stabilize the aerodynamics of the oscillating cylinder. The change of the lift phase seems important in stabilizing the cylinder aerodynamics. The change of lift phase is caused by the merger of the vortices induced by the periodic excitation with a shear layer instability frequency, and the vortex merging comes from the high growth rate, the rapid increase of wave number and decrease of phase velocity for the periodic excitation in the separated shear flows.

• 충청수학회지
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• 제20권3호
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• pp.343-348
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• 2007

In this paper, we show that if a homeomorphism has the pseudo-orbit-tracing-property and its nonwandering set is locally connected, then the limit sets of wandering points whose stable sets have nonempty interior consist of single periodic orbit.

• 충청수학회지
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• 제24권4호
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• pp.863-868
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• 2011

The purpose of this paper is to study the orbit behaviours near almost periodic points. We introduce notions of uniformly recurrent and u-recurrent points and investigate some relationships between these properties.

• 산업경영시스템학회지
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• 제45권3호
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• pp.78-89
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• 2022

The purpose of this study was to propose useful suggestion by analyzing preventive replacement policy under which there are minor and major failure. Here, major failure is defined as the failure of system which causes the system to stop working, however, the minor failure is defined as the situation in which the system is working but there exists inconvenience for the user to experience the degradation of performance. For this purpose, we formulated an expected cost rate as a function of periodic replacement time and the number of system update cycles. Then, using the probability and differentiation theory, we analyzed the cost rate function to find the optimal points for periodic replacement time and the number of system update cycles. Also, we present a numerical example to show how to apply our model to the real and practical situation in which even under the minor failure, the user of system is not willing to replace or repair the system immediately, instead he/she is willing to defer the repair or replacement until the periodic or preventive replacement time. Optimal preventive replacement timing using two variables, which are periodic replacement time and the number of system update cycles, is provided and the effects of those variables on the cost are analyzed.

• 한국추진공학회지
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• 제23권3호
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• pp.18-27
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• 2019

비정상 난류모델 (URANS)를 이용하여 가열된 이중제트의 유동혼합 특성에 대한 수치해석이 수행되었다. 압축성유동에서 난류확산이 크게 나타났고 비압축성 유동의 열확산이 압축성유동의 열확산 보다 크게 얻어졌다. 주파수와 위상궤적을 분석한 결과, 제트간격이 증가함에 따라 주기상태와 준주기상태가 관찰되었다. 제트간격이 클 경우 비정상유동구조가 제트유동 혼합의 특징을 결정하기 때문에 융합점과 결합점의 선형적 변화가 다르게 나타나는 것으로 관찰되었다.

• 대한수학회지
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• 제58권4호
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• pp.873-894
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• 2021

In this paper, we consider the Gudnason model of 𝒩 = 2 supersymmetric field theory, where the gauge field dynamics is governed by two Chern-Simons terms. Recently, it was shown by Han et al. that for a prescribed configuration of vortex points, there exist at least two distinct solutions for the Gudnason model in a flat two-torus, where a sufficient condition was obtained for the existence. Furthermore, one of these solutions has the asymptotic behavior of topological type. In this paper, we prove that such doubly periodic topological solutions are uniquely determined by the location of their vortex points in a weak-coupling regime.

• 산업경영시스템학회지
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• 제43권1호
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• pp.61-69
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• 2020

Systems such as database and socal network systems have been broadly used, and their unexpected failure, with great losses and sometimes a social confusion, has received attention in recent years. Therefore, it is an important issue to find optimal maintenance plans for such kind of systems from the points of system reliability and maintaining cost. However, it is difficult to maintain a system during its working cycle, since stopping works might incur users some troubles. From the above viewpoint, this paper discusses minimal repair maintenance policy with periodic replacement, while considering the random working cycles. The random working cycle and periodic replacement policies with minimal repair has been discussed in traditional literatures by usually analyzing cases for the nonstopping works. However, maintenance can be more conveniently done at discrete time and even during the working cycle in real applications. So, we propose that periodic replacement is planned at discrete times while considering the random working cycle, and moreover provide a model in which system, with a minimal repair at failures between replacements, is replaced at the minimum of discrete times KT and random cycles Y. The average cost rate model is used to determine the optimal number of periodic replacement.

• Structural Engineering and Mechanics
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• 제62권6호
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• pp.719-724
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• 2017

We consider an elastic isotropic plate reinforced by stringers and weakened by a periodic system of rectilinear slots of variable width. The variable width of the slots is comparable with elastic deformations. We study the case when the slots faces get in contact at some area. Determination of parameters characterizing the partial closure of variable width slots is reduced to the solution of a singular integral equation. The action of the stringers is replaced with unknown equivalent concentrated forces at the points of their connection with the plate. The contact stresses and contact zone sizes are found from the solution of the singular integral equation.