• Steel and Composite Structures
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• 제38권5호
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• pp.583-597
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• 2021

This article develops a nonclassical model to analyze bending response of squared perforated microbeams considering the coupled effect of microstructure and surface stress under different loading and boundary conditions, those are not be studied before. The corresponding material and geometrical characteristics of regularly squared perforated beams relative to fully filled beam are obtained analytically. The modified couple stress and the modified Gurtin-Murdoch surface elasticity models are adopted to incorporate the microstructure as well as the surface energy effects. The differential equations of equilibrium including the Poisson's effect are derived based on minimum potential energy. Exact closed form solution is obtained for bending behavior of the proposed model considering the classical and nonclassical boundary conditions for both uniformly distributed and concentrated loads. The proposed model is verified with results available in the literature. Influences of the microstructure length scale parameter, surface energy, beam thickness, boundary and loading conditions on the bending behavior of perforated microbeams are investigated. It is observed that microstructure and surface parameters are vital in investigation of the bending behavior of perforated microbeams. The obtained results are supportive for the design, analysis and manufacturing of perforated nanobeams that commonly used in nanoactuators, nanoswitches, MEMS and NEMS systems.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제22권1호
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• pp.29-62
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• 2018

We investigate a class of HIV infection models with two kinds of target cells: $CD4^+$ T cells and macrophages. We incorporate three distributed time delays into the models. Moreover, we consider the effect of humoral immunity on the dynamical behavior of the HIV. The viruses are produced from four types of infected cells: short-lived infected $CD4^+$T cells, long-lived chronically infected $CD4^+$T cells, short-lived infected macrophages and long-lived chronically infected macrophages. The drug efficacy is assumed to be different for the two types of target cells. The HIV-target incidence rate is given by bilinear and saturation functional response while, for the third model, both HIV-target incidence rate and neutralization rate of viruses are given by nonlinear general functions. We show that the solutions of the proposed models are nonnegative and ultimately bounded. We derive two threshold parameters which fully determine the positivity and stability of the three steady states of the models. Using Lyapunov functionals, we established the global stability of the steady states of the models. The theoretical results are confirmed by numerical simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권12호
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• pp.4372-4388
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• 2014

Robotic sensor network (RSN) contains mobile sensors and robots providing feasible solution for many multi-agent applications. One of the most critical issues in RSN and its application is how to effectively assign tasks. This paper presents a novel connectivity preserving hybrid task allocation strategy to answer the question particularly for RSN. Firstly, we model the task allocation in RSN to distinguish the discovering and allocating processes. Secondly, a fully distributed simple Task-oriented Unoccupied Neighbor Algorithm, named TUNA, is developed to allocate tasks with only partial view of the network topology. A connectivity controller is finally developed and integrated into the strategy to guarantee the global connectivity of entire RSN, which is critical to most RSN applications. The correctness, efficiency and scalability of TUNA are proved with both theoretical analysis and experimental simulations. The evaluation results show that TUNA can effectively assign tasks to mobile robots with the requirements of only a few messages and small movements of mobile agents.

• Journal of Animal Science and Technology
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• 제44권2호
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• pp.151-164
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• 2002

한우의 근내지방도 또는 임신 여부 등과 같이 이산형 분포의 성질을 갖는 다수의 형질들에 대한 유전모수 및 종축의 유전능력을 평가하기 위한 방법으로써 Threshold 모형하에서 Bayesian 추론방법의 일종인 Gibbs sampling방법을 모의실험을 통하여 알아보았으며 기록이 누락된 다수의 형질을 포함하는 다형질 Threshold 개체모형에서의 종축평가 방법론을 제시하였다. 이산형 형질의 관측치에 대응하는 임의의 잠재변수는 기록을 갖고 있는 형질들에 대한 사전정보를 고려한 사후조건확률분포에서 Gibbs sampling을 할 때 모수에 근접하는 확률분포를 얻을 수 있었으며 이러한 이산형 기록들에 대한 육종가 추정치는 선형모형에서 보다 Threshold 모형에서의 추정치가 실제 모수에 더욱 근접하는 것을 알 수 있었다. 따라서 기록이 누락된 개체들에 대한 이산형 분포를 갖는 형질들에 대하여 선형분포를 갖는 형질들과 함께 동시 유전분석할 때 Threshod 모형이 일반 선형모형 보다 적합함을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권7호
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• pp.2257-2285
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• 2022

Cyber-physical systems (CPS) have been growing exponentially due to improved cloud-datacenter infrastructure-as-a-service (CDIaaS). Incremental expandability (scalability), Quality of Service (QoS) performance, and reliability are currently the automation focus on healthy Tier 4 CDIaaS. However, stable QoS is yet to be fully addressed in Cyber-physical data centers (CP-DCS). Also, balanced agility and flexibility for the application workloads need urgent attention. There is a need for a resilient and fault-tolerance scheme in terms of CPS routing service including Pod cluster reliability analytics that meets QoS requirements. Motivated by these concerns, our contributions are fourfold. First, a Distributed Non-Recursive Cloud Model (DNRCM) is proposed to support cyber-physical workloads for remote lab activities. Second, an efficient QoS stability model with Routh-Hurwitz criteria is established. Third, an evaluation of the CDIaaS DCN topology is validated for handling large-scale, traffic workloads. Network Function Virtualization (NFV) with Floodlight SDN controllers was adopted for the implementation of DNRCM with embedded rule-base in Open vSwitch engines. Fourth, QoS evaluation is carried out experimentally. Considering the non-recursive queuing delays with SDN isolation (logical), a lower queuing delay (19.65%) is observed. Without logical isolation, the average queuing delay is 80.34%. Without logical resource isolation, the fault tolerance yields 33.55%, while with logical isolation, it yields 66.44%. In terms of throughput, DNRCM, recursive BCube, and DCell offered 38.30%, 36.37%, and 25.53% respectively. Similarly, the DNRCM had an improved incremental scalability profile of 40.00%, while BCube and Recursive DCell had 33.33%, and 26.67% respectively. In terms of service availability, the DNRCM offered 52.10% compared with recursive BCube and DCell which yielded 34.72% and 13.18% respectively. The average delays obtained for DNRCM, recursive BCube, and DCell are 32.81%, 33.44%, and 33.75% respectively. Finally, workload utilization for DNRCM, recursive BCube, and DCell yielded 50.28%, 27.93%, and 21.79% respectively.

• 한국정보통신학회논문지
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• 제4권5호
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• pp.907-917
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• 2000

본 논문은 통신망간 상호접속시 합리적인 접속료를 산정하기 위해 필요한 통신망비용모형의 수립방안을 제시하고 있다. 현재 우리나라의 통신망간 상호접속료는 기본적으로 전부배부비용방식에 의해 산정하고 있다. 이 방식은 실제발생비용을 토대로 한 회계자료에 의해 접속료를 산정하는 방식이므로 회계자료관련 문제점뿐만 아니라 효율적인 사업운영을 고려하지 못하다는 단점을 가지고 있다. 이에 주요선진국에서는 경제적 비용을 토대로 장기증분비용기준방식의 도입에 대한 검토를 하면서 합리적인 통신망비용모형의 개발에 연구를 집중하고 있다. 우리나라의 경우 현재 전면경쟁환경의 조성과 대외개방압력의 증대 등 통신환경변화로 인하여 장기증분비용기준방식의 도입여부와 함께 통신망비용모형 개발의 필요성이 요구되고 있다. 이에 본 논문에서는 합리적인 접속료 산정을 위한 통신망비용모형의 수립방안을 제시하고 있다. 기본적으로 비용을 자본비용과 운영비용으로 구분하고 각 비용특성별 비용발생원인을 파악한 후 현재의 상호접속제도와 통신회계제도를 감안하여 합리적인 비용산정방법을 검토하고 있다.

• Computers and Concrete
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• 제19권5호
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• pp.501-507
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• 2017

The predictive utility of a damage model depends heavily on its particular choice of a damage variable, which serves as a macroscopic approximation in describing the underlying micromechanical processes of microdefects. In the case of spatially perfectly randomly distributed microcracks or microvoids in all directions, isotropic damage model is an appropriate choice, and scalar damage variables were widely used for isotropic or one-dimensional phenomenological damage models. The simplicity of a scalar damage representation is indeed very attractive. However, a scalar damage model is of somewhat limited use in practice. In order to entirely characterize the isotropic damage behaviors of damaged materials in multidimensional space, a system theory of isotropic double scalar damage variables, including the expressions of specific damage energy release rate, the coupled constitutive equations corresponding to damage, the conditions of admissibility for two scalar damage effective tensors within the framework of the thermodynamics of irreversible processes, was provided and analyzed in this study. Compared with the former studies, the theoretical formulations of double scalar damage variables in this study are given in the form of matrix, which has many features such as simpleness, directness, convenience and programmable characteristics. It is worth mentioning that the above-mentioned theoretical formulations are only logically reasonable. Owing to the limitations of time, conditions, funds, etc. they should be subject to multifaceted experiments before their innovative significance can be fully verified. The current level of research can be regarded as an exploratory attempt in this field.

• 가정과삶의질연구
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• 제4권1호
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• pp.49-69
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• 1986

This study aimed to fine out the rational quantity of kitchen utensils and appliances Questionnair was distributed to families of 469 of middle school students. I studied status of kitchen work centers, quantity and the kinds of kitchen utensils. The results were as follows. 1. the status of kitchen :1) The percentage of western style work centers was significantly higher than the average level of Seoul. 2) The length and the height of work centers were below standard. 3) Arrangement of work centers was relatively correct, however, the kinds of kitchen work centers were not fully equipped. 2. The quantity of kitchen utensils: The socio-economic status were the main factor of the quantity of kitchen utensils. Educational level, income level and floor space were strongly corrected to the quantity of kitchen utensils.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.703-706
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• 2004

Grid computing represents the fundamental computing shift from a localized resource computing model to a fully-distributed virtual organization with shared resources. Accounting is one of the main obstacles to widespread adoption of the grid. Accounting has until recently, been a sparsely-addressed problem, particularly in practice. In this paper, we design and implement the accounting information gathering system. Implemented system is based on OGSA, following GSAX framework of RUS-WG in GGF. And the schema of gathered and serviced accounting information is following Usage Record Fields of UR-WG in GGF. Also, the accounting information integrating and monitoring tool for system management in the grid environment are implemented.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.89-94
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• 2002

n general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.