• Computers and Concrete
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• 제27권1호
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• pp.55-62
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• 2021

The concrete fatigue analysis can be performed with the use of fracture mechanics. The fracture mechanics defines the fatigue crack propagation as the relationship of crack growth rate and stress intensity factor. In contrast to metal, the application of fracture mechanics to concrete is more complicated and therefore many authors have introduced empirical expressions using Paris law. The topic of this paper is development of a new prediction of fatigue crack propagation for concrete using rheological-dynamical analogy (RDA) and finite element method (FEM) in the frame of linear elastic fracture mechanics (LEFM). The static and cyclic fatigue three-point bending tests on notched beams are considered. Verification of the proposed approach was performed on the test results taken from the literature. The comparison between the theoretical model and experimental results indicates that the model proposed in this paper is valid to predict the crack propagation in flexural fatigue of concrete.

• Journal of Information Processing Systems
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• 제16권6호
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• pp.1447-1458
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• 2020

This paper describes a structured overlay network scheme based on multiple different time intervals. Many types of data (e.g., sensor data) can be requested at specific time intervals that depend on the user and the system. These queries are referred to as "interval queries." A method for constructing an overlay network that efficiently processes interval queries based on multiple different time intervals is proposed herein. The proposed method assumes a ring topology and assigns nodes to a keyspace based on one-dimensional time information. To reduce the number of forwarded messages for queries, each node constructs shortcut links for each interval that users tend to request. This study confirmed that the proposed method reduces the number of messages needed to process interval queries. The contributions of this study include the clarification of interval queries with specific time intervals; establishment of a structured overlay network scheme based on multiple different time intervals; and experimental verification of the scheme in terms of communication load, delay, and maintenance cost.

• Ocean Systems Engineering
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• 제12권2호
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• pp.247-265
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• 2022

In the present study, we focus on the CFD simulations for the performance and the rotor-generated wake of a model-scale wind turbine which was designed for wave tank experiments. The CFD simulations with fully resolved rotor geometry are performed using MARIN's community-based open-source CFD code ReFRESCO. The absolute formulation method (AFM) is leveraged to model the rotating wind turbine. The k - ω SST turbulence model is adopted in the incompressible Reynolds Averaged Navier-Stokes (RANS) simulations. First, the thrust and torque coefficients, C_T and C_P, are calculated at different Tip Speed Ratios (TSR), and the results are compared against the experimental data and previous numerical results. The pressure distribution of the turbine blades at the 70% span is obtained and compared to the results obtained by other tools. Then, a verification study aiming at quantifying the discretization uncertainty of the turbine performance with respect to the grid resolution in the wake region is performed. Last, the rotor-generated wake at the TSR of 7 is presented and discussed.

• Coupled systems mechanics
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• 제10권6호
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• pp.475-490
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• 2021

With glass becoming a structural material there is a whole new approach for loading and ensuring the safety of construction. Due to its brittle nature, it is necessary to predict all possible problems so that structural integrity would not be endangered. In this paper, different approaches to modelling the glass elements are presented with references to the advantages, disadvantages, and application of each of them. The intention is clear, there is a need to improve and simplify the design guidelines. Given the increasing use of glass in construction it is not practical to produce experimental tests each time when the verification is needed. Today, architecture is bringing us different types of structures and every project presents a new challenge for engineers. A practical and simple approach is crucial for progress and efficiency. In this paper, different approaches to modelling glass are presented with an emphasis on soft body impact.

• Journal of information and communication convergence engineering
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• 제20권4호
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• pp.273-279
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• 2022

Owing to the need to establish a cooperative-intelligent transport system (C-ITS) environment in the transportation sector locally and abroad, various research and development efforts such as high-tech road infrastructure, connection technology between road components, and traffic information systems are currently underway. However, the current central control center-oriented information collection and provision service structure and the insufficient road infrastructure limit the realization of the C-ITS, which requires a diversity of traffic information, real-time data, advanced traffic safety management, and transportation convenience services. In this study, a network construction method based on the existing received signal strength indicator (RSSI) selected as a comparison target, and the experimental target and the proposed intelligent edge network compared and analyzed. The result of the analysis showed that the data transmission rate in the intelligent edge network was 97.48%, the data transmission time was 215 ms, and the recovery time of network failure was 49,983 ms.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.568-573
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• 1996

In this paper, A design strategy of the Surface Mounting Device for accurate and better performance is studied. Analytical Modeling. Sensitivity analysis and optimization are being conducted. The ANSYS software and experimental method are used for verification of the analytical equations withboundary conditons. Through the sensitivity analysis, the most dominant design parameters can be detected. The optimum design parameters for performing given performing given perfomances are selected by using the optimization algorithm. The design tool based on the design strategy for the analysis, modeling and optimization will be useful for a re-design and better perofrmance of the SMD.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1789-1794
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• 2003

As a new approach to analyze shear behaviors in the shear plane and chip-tool friction behaviors in the chip-tool contact region during an end milling process, this paper introduces a method to transform an end milling process to an equivalent oblique cutting process. In this approach, varying undeformed chip thicknesses and cutting forces in the up-and down-end milling process are replaced with the equivalent ones of oblique cutting. Accordingly, in the current paper, the shear and friction characteristics of end milling operations, up- and down-end milling, have been analyzed based on the equivalent oblique cutting models. Two series of cutting tests, up- and down-end milling tests and the equivalent oblique cutting tests to that, have been carried out to verify the validity of the analyses. And using the results of cutting tests the cutting characteristics of the up- and down-end milling processes have been thoroughly investigated.

• 한국정밀공학회지
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• 제14권2호
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• pp.120-128
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• 1997

In this paper, A design strategy of the Surface Mounting Device for accurate and better performance is studied. Analytical modeling, sensitivity analysis, and optimization are being conducted. The ANSYS software and experimental method are used for the verification of the analytical equations with boundary conditions. Through the sensitivity analysis, the most dominant design parameter can be detected. The optimum design parameters for improving the given performances are selected by using the optimiza- tion algorithm. The design tool based on the design strategy for the analysis, modeling, and optimization will be useful for are-design and better improving of the SMD.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.54-55
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• 2021

This study compared the fire safety standards for windows of Korea, the U.S. and Japan to prevent fire expansion through exterior wall openings, and conducted experiments using PVC and aluminum window frames, which are widely used in Korea.The experiment is KS F 2845 which combines frames of the same thickness and area with single-window form and 1 hour fire resistance glass with 8T thickness. Experiments showed that the PVC window was about 9 minutes and the aluminum window was about 26 minutes. However, in Korea, there are no test standards for windows installed at the opening of the exterior wall. In addition, fire safety standards for windows shall be established along with the designation of fire prevention zones.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.59-60
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• 2022

According to the recent issue regarding the shortage of concrete supply, it is common to appoint various concrete suppliers and allow mixed pouring according to the specification requirements. Moreover, if the concrete is mixed inevitably a strength and property test is carried out for verification. Therefore, in this research, multiple concrete suppliers were selected and each required raw material was collected for the test of all variable mixed design. Through the test, the property of the unhardened and hardened concrete was quantitatively evaluated.