• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.286-290
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• 2011

This paper introduces the optimum macro-siting of a potential site for an offshore wind farm around Jeju Island using the RDAPS sea wind model. The statistical model was developed by analyzing the sea wind data from RDAPS model, and the meso-scale digital wind map was prepared. To develop the high resolution spatial calibration model, Artificial Neural Network(ANN) models were used to construct the wind and bathymetric maps. Accuracy and consistency of wind/bathymetric spatial calibration models were obtained using analysis of variance. The optimization problem was defined to maximize the energy density satisfying the criteria of maximum water depth and maximum distance from the coastline. The candidate site was selected through Genetic Algorithm(GA). From the results, it is possible to predict roughly a candidate site location for the installation of the offshore wind jam, and to evaluate the wind resources of the proposed site.

• Advances in aircraft and spacecraft science
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• v.10 no.1
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• pp.83-106
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• 2023

In this work, the static behavior of FGM macro and nano-plates under thermomechanical loading. Equilibrium equations are determined by using virtual work principle and local and non-local theory. The novelty of the current model is using a new displacement field with four variables and a warping function considering the effect of shear. Through this analysis, the considered sandwich FGM macro and nanoplates are a homogeneous core and P-FGM faces, homogeneous faces and an E-FGM core and finally P-FGM faces and an E-FGM core. The analytical solution is obtained by using Navier method. The model is verified with previous published works by other models and very close results are obtained within maximum 1% deviation. The numerical results are performed to present the influence of the various parameters such as, geometric ratios, material index as well as the scale parameters are investigated. The present model can be applicable for sandwich FG plates used in nuclear, aero-space, marine, civil and mechanical applications.

• Environmental Engineering Research
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• v.16 no.1
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• pp.47-51
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• 2011

The oxygen transfer rate is a parameter that characterizes the gas-liquid mass transfer in surface aerators. Gas-liquid transfer mechanisms in surface aeration tanks depend on two different extreme lengths of time; namely, macromixing and micromixing. Small scale mixing close to the molecular level is referred to as micromixing; whereas, macromixing refers to mixing on a large scale. Using experimental data and numerical simulations, macro- and micro-scale parameters describing the two extreme time scales were investigated. A scale up equation to simulate the oxygen transfer rate with micromixing times was developed in geometrically similar baffled surface aerators.

• Transactions of Materials Processing
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• v.21 no.5
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• pp.319-323
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• 2012

In order to predict the internal void closing behavior in open die forging process, multiple scale modeling has been developed and applied. The huge size difference between ingot and inner void makes it almost impossible to simultaneously model the actual loading conditions and the void shape. Multiple scale modeling is designed to integrate macro- and micro- models effectively and efficiently. The void closing behavior was simulated at 39 different locations in a large ingot during upsetting and cogging. The correlation between the closing behavior and variables such as effective plastic strain and maximum compressive strain was studied in order to find an efficient measure for predicting the soundness of the forging.

• Computers and Concrete
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• v.33 no.3
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• pp.325-340
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• 2024

The growing demands for sustainable and high-performance construction materials necessitate a deep understanding of their physicochemical properties by that of these heterogeneities. This paper presents a comprehensive review of the state-of-the-art hierarchical multiscale modeling approach aimed at predicting the intricate physicochemical characteristics of construction materials. Emphasizing the heterogeneity inherent in these materials, the review briefly introduces single-scale analyses, including the ab initio method, molecular dynamics, and micromechanics, through a scale-bridging technique. Herein, the limitations of these models are also overviewed by that of effectively scale-bridging methods of length or time scales. The hierarchical multiscale model demonstrates these physicochemical properties considering chemical reactions, material defects from nano to macro scale, microscopic properties, and their influence on macroscopic events. Thereby, hierarchical multiscale modeling can facilitate the efficient design and development of next-generation construction.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.97-103
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• 2006

A meso-scale analysis method using the natural element method, which is a kind of meshless method, is proposed for the analysis of material damage of brittle microcracking solids such as ceramic materials, concrete and rocks. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The macro elastic moduli of anisotropic as well as isotropic solids containing a number of randomly distributed microcracks are calculated in order to demonstrate the validity of the proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1703-1711
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• 2010

Electric power utilities are facing increasing uncertainties regarding the economic, political, societal, environmental constraints under they operate and plan their future systems. The utilities have to integrate consumers' interruption cost representing reliability worth of electricity into the process of determining the optimum investment level. In order to do so, the estimated outage cost must be included into quantitative index corresponding to system capital and operation investment cost to establish an optimal expansion plan. This paper is a study on the outage cost assessment by using macro approach for calculating IEAR(Interrupted Energy Assessment Rates) and the TRELSS(Transmission Reliability Evaluation for Large-Scale Systems) program was used to calculate EENS(Expected Energy Not Served).

• Corrosion Science and Technology
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• v.3 no.3
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• pp.87-97
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• 2004

This paper presents a new approach with meso scale structure models to express mechanical property, such as stress - strain relationships, of concrete. This approach is successful to represent both uniaxial tension and uniaxial compression stress - strain relationship, which is in macro scale. The meso scale approach is also applied to predict degraded mechanical properties of frost-damaged concrete. The degradation of mechanical properties with frost-damaged concrete was carefully observed. Strength and stiffness in both tension and compression decrease with freezing and thawing cycles (FTC), while stress-free crack opening in tension softening increases. First attempt shows that the numerical simulation can express the experimentally observed degradation by introducing changes in the meso scale structure in concrete, which are assumed based on observed damages in the concrete subjected to FTC. At the end applicability of the meso scale approach to prediction of the degradation by combined effects of salt attack and FTC is discussed. It is shown that clarification of effects of frost damage in concrete on corrosion progress and on crack development in the damaged cover concrete due to corrosion is one of the issues for which the meso scale approach is useful.

• Journal of English Language & Literature
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• v.64 no.3
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• pp.469-481
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• 2018

When literatures and cultures encounter their counterparts in terms of the big data or statistics of a new reconfiguration in the cognitive map, the tangential points of the borderland will be reduced to what Mitchell calls "a mere abstraction on a map," which nevertheless will provide a vast interstitial zone of "intersections, competition, and exclusions." This zone will be the dynamic vortex for the aesthetics, politics, and ethics of cultural translation. The translated discourse will engage in carrying across the disturbing region of untranslatability and demonstrate how the literary texts of world literature reveal enriching but threatening human experience. This dynamic border of vortex will construct the translational space of world literature, transcending the fragmentary untranslatable nature of the hybrid convergence of the ethnic, racial, cultural and national intermixtures and constructing what Pascal Casanova terms "The World Republic of Letters." In this paper, I will demonstrate how the very concept of scale is related to literary space as well as how distance creates a poetics of literary landscapes which looks ahead of world literature. Also, I will attempt to find the possibility to relate the "micro-scale" with the "macro-scale," and to construct the scale politics of representation. "Glocalization" is a convenient theoretical tool for the double movement of the up-scale and down-scale.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.137-145
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• 2014

We present a design sensitivity analysis(DSA) method for multiscale problems based on bridging scale decomposition. In this paper, we utilize a bridging scale method for the coupled system analysis. Since the analysis of full MD systems requires huge amount of computational costs, a coupled system of MD-level and continuum-level simulation is usually preferred. The information exchange between the MD and continuum levels is taken place at the MD-continuum boundary. In the bridging scale method, a generalized Langevin equation(GLE) is introduced for the reduced MD system and the GLE force using a time history kernel is applied at the boundary atoms in the MD system. Therefore, we can separately analyze the MD and continuum level simulations, which can accelerate the computing process. Once the simulation of coupled problems is successful, the need for the DSA is naturally arising for the optimization of macro-scale design, where the macro scale performance of the system is maximized considering the micro scale effects. The finite difference sensitivity is impractical for the gradient based optimization of large scale problems due to the restriction of computing costs but the analytical sensitivity for the coupled system is always accurate. In this study, we derive the analytical design sensitivity to verify the accuracy and applicability to the design optimization of the coupled system.