• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.2
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• pp.71-77
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• 2000

A multi-region model for solute transport through saturated soils has been developed to describe preferential flow. The model consists of numerous discrete pore groups, which are characterized by a discrete dispersion coefficient, flow velocity, and porosity . The hydraulic properties for each pore group are derived from a soil's hydraluic conductivity and soil water characteristic functions . Flow in pore group is described by the classical advection-disersion equation (ADE). An implict finite difference scheme was applied to the governing equation that results in a block-tridiagonal system of equations that is very efficient and allows the soil to be divided into any number of pore groups. The numerical technique is derived from methods used to solve coupled equations in fluid dynamics problems and can also be applied to the transport of interacting solutes. The results of the model are compared to the experimental data from published papers. This paper contributes on the characteristics of the method when applied to the parallel porosity model to describe preferential flow of solutes in soil.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.11a
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• pp.109-109
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• 1993

CANDU 원자로 지역별 대표 핵연료봉 1개에 대하여 열행태를 해석할 수 있는 '평균 단일 핵연료(ASF : Averaged Single Fuel)' 모델을 우선 제안하였다. 핵 연료봉 하나를 12 개 동일 체적의 환형 격자로 나누고 시공간을 고려하는 전진 유한 미분 해석을 적용하여 핵연료봉내에서의 열적 변이를 모사 하였다. 핵연료의 전도도 및 비열은 온도에 종속함이 가정되었다. 주어진 열출력에 대하여, 핵연료와 피복관내의 정상상태 온도분포를 산출하였고 주어진 냉각재 온도 및 표면 열 전달 계수에 대하여 핵연료봉 단위 길이당 저장열을 계산하였다. 초기 온도 분포의 임의 값에 대하여, 시간 단계별 열출력 및 열전달 계수 변이에 따른 저장열, 온도 분포, 냉각재료의 출력과 피복관 온도 변이를 계산하였다. 이후 ASF 모델을 CANDU 14개 지역 출력 특성의 실제적 모사 및 해석이 가능하도록, 14개 지역 대표 핵연료봉모델 모두를 동시에 포함하는 '다영역 핵연료(MZF : Multi Zone Fuel)' 모델로 확장하였다.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.3-12
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• 2000

The multi-region model, to describe preferential flow, is an equation representing solute transport in soils by dividing soil into numerous pore groups and using the hydraulic properties of the soil. As the model partial differential equation (PDE) is solved numerically with finite difference methods. a modified equivalent partial differential equation(MEPDE) of the partial differential equation of the multi-region model is derived to analyze the accuracy and consistency of the solution of the model PDE and the Von Neumann method is used to analyze the stability of the finite difference scheme. The evaluation obtained from the MEPDE indicated that the finite difference scheme was found to be consistent with the model PDE and had the second order accuracy The stability analysis is performed to analyze the model PDE with the amplification ratio and the phase lag using the Von Neumann method. The amplification ratio of the finite difference scheme gave non-dissipative results with various Peclet numbers and yielded the most high values as the Peclet number was one. The phase lag showed that the frequency component of the finite difference scheme lagged the true solution. From the result of the stability analysis for the model PDE, it is analyzed that the model domain should be discretized in the range of Pe < 1.0 and Cr < 2.0 to obtain the more accurate solution.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.2
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• pp.78-85
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• 2000

The moment equations of the concentration distribution for the multi-region model are derived using the method of moment. The method originally devised by Aris is to obtain the concentration moments satisfying a given PDE (Partial Differential Equation. The method of moment is used to obtain the first five moments (0th to 4to) that satisfy the model PDE. Each moment of the concentration distribution for the model equation is plotted for the dimensionless time and gave similar results except the skewness and the kurtosis. The results of the analysis show the physical meaning of each moment. The comparisons with the number of regions or the global interaction coefficient give a possibility to determine the parameters of the multi-region model with the analytical concepts.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.600-601
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• 2021

The cyberspace, which is the fifth battle field, should be utilized for multi-domain maneuvering between the cyberspace and the physical space using an electromagnetic spectrum. This becomes a major concept of cyber electronic warfare that combines the characteristics of cyber warfare and electronic warfare. In this study, the concept of cyber electronic warfare is analyzed by using the OSI reference model and examining the threats of the two-layer data link layer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.757-765
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• 2021

To carry out multi-domain operations included in the U.S. Department of Defense's national security strategy in 2018, timely data sharing between C4I systems is critical. Several studies of the Korean military have also raised the problems of interface and standardization between C4I systems, and it is necessary to establish a new plan to solve this problem. In this study, a solution to the problem was derived through case analysis that the U.S. Department of Defense has been pursuing for about 20 years to implement the data strategy after establishing the data strategy in 2003. and by establishing a data strategy suitable for the ROK military C4I system operating environment, developing a data model, selecting a standard for data sharing, and proposing a shared data development procedure, we intend to improve the data sharing capability between ROK military C4I systems.