• Nuclear Engineering and Technology
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• 제44권2호
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• pp.103-122
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• 2012

Significant advances in computational performance have occurred over the past two decades, achieved not only by the introduction of more powerful processors but the incorporation of parallelism in computer hardware at all levels. Simultaneous with these hardware and associated system software advances have been advances in modeling physical phenomena and the numerical algorithms to allow their usage in simulation. This paper presents a review of the advances in computer performance, discusses the modeling and simulation capabilities required to address the multi-physics and multi-scale phenomena applicable to a nuclear reactor core simulator, and present examples of relevant physics simulation codes' performances on high performance computers.

• Structural Engineering and Mechanics
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• 제55권1호
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• pp.191-204
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• 2015

Control of the mechanical behavior of composite materials and structures under monotonic and dynamic loads for cracks and damage is a vast and complex area of research. The modeling of the different physical phenomena and behavior characteristics of a composite material during deformation play an important role in the structural design. Our study aims to analyze numerically the energy release rate parameter G of a composite laminated plate (glass or boron / epoxy) cross-ply [$+{\alpha}$, $-{\alpha}$] in the presence of a crack between two circular notches under the effect of several parameters such as fiber orientation ${\alpha}$, the crack orientation ${\beta}$, the orientation ${\gamma}$ of the two considered circular notches and the effect of mechanical properties. Our results show clearly that both notches orientation has more effect on G than the cracks and fibers orientations.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.288-291
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• 2008

Physics based Cellular Automata model is developed and implemented into FEM code. CA model can predict microstructure evolution based on physical phenomena, such as hardening, recovery and recrystallization. This paper outlines the methodology to determine the materials constants for these different phenomena from simpler measurements.

• 전자통신동향분석
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• 제39권4호
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• pp.42-53
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• 2024

Mathematical modeling is the process of representing physical phenomena using equations, and it often describes various scientific phenomena through differential equations. Numerical analysis, which is capable of approximating solutions to partial differential equations representing physical phenomena, is widely utilized. However, in high-dimensional or nonlinear systems, computational costs can substantially increase, leading to potential numerical instability or convergence issues. Recently, Physics-Informed Neural Networks (PINNs) have emerged as an alternative approach. A PINN leverages physical laws even with limited data to provide highly reliable predictive performance and can address the convergence issues and high computational costs associated with numerical analysis. This paper analyzes the weak signals, research trends, patent trends, and case studies of PINNs. On the basis of this analysis, it proposes directions for the development of PINN techniques in the agricultural field. In particular, the application of PINNs in agriculture is expected to be more effective than in other industries because of their ability to reflect real-time changes in biological processes. While the technology readiness level of PINNs remains low, the potential for model training with minimal data and real-time prediction capabilities suggests that PINNs could replace traditional numerical analysis models. It is anticipated that the research and industrial applications of PINN will develop at an increasing pace while focusing on addressing the complexity of mathematical models in agriculture, mathematical modeling and the application of various biological processes; securing key patents related to PINNs; and standardizing PINN technology in the field of agriculture.

• Journal of Power Electronics
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• 제11권3호
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• pp.381-388
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• 2011

This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N- region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제6권1호
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• pp.53-63
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• 2002

This study investigates the impact of Calculator-Based Ranger (CBR) activities in the performance of middle school students' graphing abilities of physical phenomena. Two issues about CBR activities on graphing abilities were addressed in this study; (1) the effect of CBR activities on graphing abilities, and (2) the influence of instructional styles on students' graphing abilities. Following the use of CBR activities, students' graphing abilities were significantly more developed in three components-interpreting, modeling, and transforming. Significant differences were found in students' achievement depending on instructional styles related to differentiation, which is closely connected to transforming distance-time graphs to velocity-time graphs. The findings of this study indicate that CBR activities may enhance students in constructing appropriate webs of related concepts and ability to qualitatively interpret graphs. Using collaborative CBR activities to introduce and explore graphing of physical phenomena is, therefore, recommended for inclusion in the secondary mathematics curriculum.

• 대한기계학회논문집
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• 제17권6호
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• pp.1465-1477
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• 1993

본 연구에서는 분말혼합체의 특성인 항복응력을 포함한 Generalized Newtonian Fluid의 구성 방정식을 도입하고 미끄럼현상을 고려한 신소재의 사출성형 충전과정 해석용 CAE(computer aided engineering)시스템을 개발하였다. 수치모사를 위한 수치해석방법으로는, 유한요소법(finite element method)과 유한차분법(finite difference method)을 함께 사용하였다. 유한요소법과 검사체적법(control volume technique) 을 병용하여 유동의 진행을 수치모사 하였으며, 유한차분법을 사용하여 온도분포를 계산하였다.

• Nuclear Engineering and Technology
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• 제41권1호
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• pp.11-20
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• 2009

Radiation effects on materials are inherently multiscale phenomena in view of the fact that various processes spanning a broad range of time and length scales are involved. A multiscale modeling approach to embrittlement of pressure vessel steels is presented here. The approach includes an investigation of the mechanisms of defect accumulation, microstructure evolution and the corresponding effects on mechanical properties. An understanding of these phenomena is required to predict the behavior of structural materials under irradiation. We used molecular dynamics (MD) simulations at an atomic scale to study the evolution of high-energy displacement cascade reactions. The MD simulations yield quantitative information on primary damage. Using a database of displacement cascades generated by the MD simulations, we can estimate the accumulation of defects over diffusional length and time scales by applying kinetic Monte Carlo simulations. The evolution of the local microstructure under irradiation is responsible for changes in the physical and mechanical properties of materials. Mechanical property changes in irradiated materials are modeled by dislocation dynamics simulations, which simulate a collective motion of dislocations that interact with the defects. In this paper, we present a multi scale modeling methodology that describes reactor pressure vessel embrittlement in a light water reactor environment.

• Nuclear Engineering and Technology
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• 제31권6호
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• pp.51-65
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• 1999

The present review report introduces the existing analysis codes and physical modeling of two-phase flow associated with initiating event of HCDA in Liquid Metal Reactors for the effective study in the future, because the related research has not been systematically carried out in Korea compared with other areas. The description in this report is specifically addressed to the results yielded from careful review of the technical concepts on the two-phase flow modeling in the SAS2A code which was developed in ANL. The report is prepared in 2 parts based on the definite physical phenomena. The liquid slug and gas behavior models are main representations in the part (I) and (II), respectively. In this regard, it is expected that this report provide a fundamental knowledge on the two-phase flow model in LMR and, thus, contribute to establishment of the necessary HCDA analysis technology concerned with the LMR development in Korea.

• 한국대기환경학회지
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• 제15권5호
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• pp.625-638
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• 1999

Air quality modeling for coastal urban region has been composed of a complex system including meteorological, chemical and physical processes and emission characteristics in complex terrain. In this study, we studied about an effect prediction for deposition phenomenon affecting on air quality in Pusan metopolitan metropolitan city. In air quality modeling including ship sources, a situation considered deposition process habe better result than not considered when compared with observed value. Air pollutants emitted into urban air during the daytime nearly removed through urban atmosphere polluted. Also these phenomena correlated concentration variation connent with sea/land breezes and terrain effect. Therefore we conclude that the concentration was low at daytime when deposition flux is high, and deposition effect on industrial complex and Dongrae region is considerable in particular.