• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3030-3049
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• 2023

With the development and wide application of hybrid network computing modes like cloud computing, edge computing and fog computing, the customer service requests and the collaborative optimization of various computing resources face huge challenges. Considering the characteristics of network environment resources, the optimized deployment of service resources is a feasible solution. So, in this paper, the optimal goals for deploying service resources are customer experience and service cost. The focus is on the system impact of deploying services on load, fault tolerance, service cost, and quality of service (QoS). Therefore, the alternate node filtering algorithm (ANF) and the adjustment factor of cost matrix are proposed in this paper to enhance the system service performance without changing the minimum total service cost, and corresponding theoretical proof has been provided. In addition, for improving the fault tolerance of system, the alternate node preference factor and algorithm (ANP) are presented, which can effectively reduce the probability of data copy loss, based on which an improved cost-efficient replica deployment strategy named ICERD is given. Finally, by simulating the random occurrence of cloud node failures in the experiments and comparing the ICERD strategy with representative strategies, it has been validated that the ICERD strategy proposed in this paper not only effectively reduces customer access latency, meets customers' QoS requests, and improves system service quality, but also maintains the load balancing of the entire system, reduces service cost, enhances system fault tolerance, which further confirm the effectiveness and reliability of the ICERD strategy.

• 대한기계학회논문집A
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• 제20권2호
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• pp.450-460
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• 1996

To investigate the effect of stress wave propagation for crack tip, impact responses of two-dimensional plates with oblique cracks are investigated by a numerical method. In the numerical analysis, the finite element method is used in space domain discretization and the Newmark constant acceleration algorithm is used in time integration. According to the numerical results from the impact response analysis. it is found that the stress fields are bisected at the crack surface and the parts of stress intensity are moved along the crack face. The crack tip stress fields are yaried rapidly. The magnitude of crack tip stress fields are converted to dynamic stress intensity factor. Dynamic sress intensity factor appears when the stress wave has reached at the crack tip and the aspect of change of dynamic stress intensity factor is shown to be the same as the part of the flow of stress intensity.

• Steel and Composite Structures
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• 제41권6호
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• pp.805-820
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• 2021

In this research, the buckling and free vibration of three-phase carbon nanotubes/ fiber/ polymer piezoelectric nanocomposite face sheet sandwich microbeam with microsensor and micro-actuator surrounded in elastic foundation based on modified couple stress theory (MCST) is investigated. Three types of porous materials are considered for sandwich core. Higher order (Reddy) and sinusoidal shear deformation beam theories are employed for the displacement fields. Sinusoidal surface stress effects are extracted for sinusoidal shear deformation beam theory. The equations of motion are derived by Hamilton's principle and then the natural frequency and critical buckling load are obtained by Navier's type solution. The determined results are in good agreement with other literatures. The detailed numerical investigation for various parameters is performed for this microsensor-microactuator. The results reveal that the microsensor-microactuator enhanced by increasing of Skempton coefficient, carbon nanotubes diameter length to thickness ratio, small scale factor, elastic foundation, surface stress constants and reduction in porous coefficient, micro-actuator voltage and CNT weight fraction. The valuable results can be expedient for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

• 대한기계학회논문집
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• 제14권1호
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• pp.96-102
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• 1990

본 연구에서는 압력용기 소재인 SPV 50Q와 고압강관 소재로 사용하는 SPV 50Q 와 고압강간 소재로 사용하는 API 5A-K55에서의 표면균열의 표면방향과 깊이방향 또한 두께 평균에 대한 균열열림을 스트레인 게이지와 CMOD(Crack Mouth Opening Displace- ment)게이지를 이용하여 측정 비교하였다. 또한 표면균열의 균열 열림하중을 측정위 치에 따라 평가하고, 본연구에 사용한 두 소재에 대해 균열 열림을 고려한 표면균열 진전평가가 각 방향에 대해 이루어졌다.

• Composites Research
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• 제24권1호
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• pp.17-23
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• 2011

풀아웃 하중을 받는 복합재 샌드위치 체결부의 파손 거동을 시험으로 연구하였다. 체결의 방식과 코어의 종류를 달리하여 5종류, 총 30개의 시편에 대해 시험을 수행하였다. 시험 결과, 노멕스 하니콤 코어를 사용할 경우 코어의 강성에 의해 지배되는 전단좌굴이 먼저 발생하고, 이후 50~200% 정도의 추가적인 하중을 지지하다가, 면재가 찢어지는 최종파손이 발생하였다. 반면에 PMI 폼을 사용하면 하중 초기에 코어의 전단파손이 발생하며 지지하중도 크게 저하되는 것을 확인하였다. 파손모드를 고려한 설계의 관점에서 볼 때, 노멕스 코어를 사용할 경우 코어의 강성과 면재의 강성 및 강도를 동시에 고려해야 하는 반면, 폼 코어를 사용할 경우 코어의 전단파손 하중을 높이는 것이 가장 중요한 것으로 나타났다.

• Computers and Concrete
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• 제7권5호
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• pp.437-453
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• 2010

CFRP has been widely used for strengthening reinforced concrete members in last decade. The strain transfer mechanism from concrete face to CFRP is a key factor for rigidity, ductility, energy dissipation and failure modes of concrete members. For these reasons, determination of the effective CFRP bonding length is the most crucial step to achieve effective and economical strengthening. In this paper, generalizations are made on effective bonding length by increasing the amount of test data. For this purpose, ANSYS software is employed, and an experimentally verified nonlinear finite element model is prepared. Special contact elements are utilized along the concrete-CFRP strip interface for investigating stress distribution, load-displacement behavior, and effective bonding length. Then results are compared with the experimental results. The finite element model found consistent results with the experimental findings.

• International Journal of Railway
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• 제5권2호
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• pp.71-76
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• 2012

Recently, axle load, operating speed and traffic density on railroads have had a tendency to increase and thereby cause additional pressure applied on used track. These operating conditions frequently result in service failure due to wear caused by wheel-rail contact and fatigue damage under cyclic loading. Among rail defects, the transverse crack, which has been the most dangerous type of fatigue damages, is developed from the subsurface crack near the rail running face and grows perpendicular to the rail surface. Therefore, it is necessary to investigate systematically the growth behavior of transverse crack for rail steel under mixed mode. In this study, the fatigue crack growth behavior of the transverse crack in rail steel was experimentally investigated under mixed-mode variable amplitude loadings.

• Wind and Structures
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• 제31권5호
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• pp.431-443
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• 2020

The modern tall buildings are often constructed as an unconventional plan and as twin buildings. Wind load on the tall building is significantly influenced by the presence of another building in the near vicinity. So, it is imperative to study wind forces on an unconventional plan shaped tall building. Mean wind pressure coefficients of a square and 'H' plan shape tall buildings are investigated using wind tunnel experiments. The experiments were carried out for various wind directions from 00 to 900 at an interval of 300 and various locations of the identical interfering building. The experimental results are presented at the windward face from the viewpoint of effects on cladding design. To quantify the interference effects, interference factors (I.F) are calculated. Mean pressure coefficients of both models are compared for isolated and interference conditions. The results show that pressure reduces with an increase in wind angle till 600 wind direction. The interfering building at full blockage interference condition generates more suction than the other two conditions. The interference factor for both models is less than unity. H-plan building model is subjected to a higher pressure than the square model.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.863-872
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• 2021

The main goal of this research is to understand how small and medium enterprises (SMEs) owners in Oman perceive the factors that drive or impede their growth and sustainability. Based on survey data of 395 SMEs in Oman, factor analysis was conducted to check if all the items load as one factor in each of the constructs. The results show that all the items measuring motivators and barriers loaded significantly for the respective scales, with high reliability (Cronbach alpha for Motivators = 0.991 and Barriers = 0.995). Relationships between the demographic factors of entrepreneurs and firm characteristics were tested and it was found that all the four variables: age of the entrepreneur (p = 0.00), qualification of the entrepreneur (p = 0.00), SME sector (p = 0.00), and age of the firm (p = 0.00) have a significant relationship with both the Motivators and the Barriers. The findings of this study could have significant implications for policymakers in Oman and other Middle Eastern countries. Since SMEs face similar problems and are given priority around the world, the findings could be applicable to other countries, as well. The findings also add important results to the empirical literature on SMEs.

• Ocean Systems Engineering
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• 제6권1호
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• pp.61-97
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• 2016

This is the second of two papers on the 3D numerical modeling of nearshore hydro- and morphodynamics. In Part I, the focus was on surf and swash zone hydrodynamics in the cross-shore and longshore directions. Here, we consider nearshore processes with an emphasis on the effects of oceanic forcing and beach characteristics on sediment transport in the cross- and longshore directions, as well as on foreshore bathymetry changes. The Delft3D and XBeach models were used with four turbulence closures (viz., ${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES) to solve the 3D Navier-Stokes equations for incompressible flow as well as the beach morphology. The sediment transport module simulates both bed load and suspended load transport of non-cohesive sediments. Twenty sets of numerical experiments combining nine control parameters under a range of bed characteristics and incident wave and tidal conditions were simulated. For each case, the general morphological response in shore-normal and shore-parallel directions was presented. Numerical results showed that the ${\kappa}-{\varepsilon}$ and H-LES closure models yield similar results that are in better agreement with existing morphodynamic observations than the results of the other turbulence models. The simulations showed that wave forcing drives a sediment circulation pattern that results in bar and berm formation. However, together with wave forcing, tides modulate the predicted nearshore sediment dynamics. The combination of tides and wave action has a notable effect on longshore suspended sediment transport fluxes, relative to wave action alone. The model's ability to predict sediment transport under propagation of obliquely incident wave conditions underscores its potential for understanding the evolution of beach morphology at field scale. For example, the results of the model confirmed that the wave characteristics have a considerable effect on the cumulative erosion/deposition, cross-shore distribution of longshore sediment transport and transport rate across and along the beach face. In addition, for the same type of oceanic forcing, the beach morphology exhibits different erosive characteristics depending on grain size (e.g., foreshore profile evolution is erosive or accretive on fine or coarse sand beaches, respectively). Decreasing wave height increases the proportion of onshore to offshore fluxes, almost reaching a neutral net balance. The sediment movement increases with wave height, which is the dominant factor controlling the beach face shape.