• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.384-388
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• 2001

The higher order singularities[1] are systematically examined, and discussed are their complementarity relation with the nonsingular eigenfunctions and their relations to the configurational forces like J-integral and M-integral. By use of the so-called two state conservation laws(Im and Kim[2]) or interaction energy, originally proposed by Eshelby[3] and later treated by Chen and Shield[4], the intensities of the higher order singularities are calculated, and their roles in elasticplastic fracture are investigated. Numerical examples are presented for illustration.

• 대한수학회보
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• 제57권1호
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• pp.219-244
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• 2020

In this paper, we approximate the solution of the coupled nonlinear Schrödinger equations by using a fully discrete finite element scheme based on the standard Galerkin method in space and implicit midpoint discretization in time. The proposed scheme guarantees the conservation of the total mass and the energy. First, a priori error estimates for the fully discrete Galerkin method is derived. Second, the existence of the approximated solution is proved by virtue of the Brouwer fixed point theorem. Moreover, the uniqueness of the solution is shown. Finally, convergence orders of the fully discrete Crank-Nicolson scheme are discussed. The end of the paper is devoted to some numerical experiments.

• 대한수학회논문집
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• 제20권3호
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• pp.589-602
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• 2005

We present the numerical algorithm for the model for high-strain rate deformation in hyperelastic-viscoplastic materials based on a fully conservative Eulerian formulation by Plohr and Sharp. We use a hyperelastic equation of state and the modified Steinberg and Lund's rate dependent plasticity model for plasticity. A two-dimensional approximate Riemann solver is constructed in an unsplit manner to resolve the complex wave structure and combined with the second order TVD flux. Numerical results are also presented.

• 천문학회보
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• 제40권2호
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• pp.38.2-38.2
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• 2015

Development of a new code for magnetohydrodynamic (MHD) phenomena in fusion plasma is under progress through a collaboration between plasma physicists, mathematicians, and astrophysicists. The code employs approaches different from those of existing codes. For instance, it is based on a finite difference scheme of high-order and high accuracy, complying conservation laws. The new code will have characteristics distinguished from those of commonly used code such as M3D and NIMROD. Here we will report the progress of the code development.

• 대한수학회보
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• 제45권1호
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• pp.191-205
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• 2008

In this paper, we construct the analytic solutions and numerical solutions for a two-dimensional Riemann problem for Burgers' equation. In order to construct the analytic solution, we use the characteristic analysis with the shock and rarefaction base points. We apply the composite scheme suggested by Liska and Wendroff to compute numerical solutions. The result is coincident with our analytic solution. This demonstrates that the composite scheme works pretty well for Burgers' equation despite of its simplicity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.86-87
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• 2003

Unstructured grid system is suitable for flows of complex geometries. For problems with moving boundary walls, the grid system must be changed and deformed with time if we use a body fitted grid system. In this paper, a new moving-grid finite-volume method on unstructured grid system is proposed and developed for unsteady compressible flows with shock waves. To assure geometric conservation laws on moving grid system, a control volume on the space-time unified domain is adopted for estimating numerical flux. The method is described and applied for two-dimensional flows.

• 환경영향평가
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• 제12권1호
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• pp.1-8
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• 2003

The Master Plan of Natural Environment Conservation in Korea by Ministry of Environment has been carried out since 1986. The 2nd 10-year survey started in 1997, and there are three major parts in the Master Plan : First, the basic natural environment survey, second, sites in special features of ecological characteristics such as uninhabitable islands, wetlands, etc, and third, biological species featuring status of habitat, and population dynamics. However the information in the Master Plan is very fragmented and collected data are not so abundant due to insufficient man-power and unsynchronized survey time/season. In this regard this paper examined the similar National Biological Survey in USA and compared the differences with the Master Plan in Korea. The Master Plan in Korea should separate the management zone based on hydrological characteristics, and in each zone we should set a management goal in the long term basis. Secondly the species list is not so meaningful that we must concentrate more on research activities. In each taxonomical group we set up hypotheses and research goals. Thirdly local residents and communities should be involved in research so that enhanced biological diversity should benefit people in areas. Lastly legislation and laws should be reexamined and rectified to provide information to the managers that deals with natural resources, expecially when conflicting with economic matters.

• 한국습지학회지
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• 제6권1호
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• pp.89-104
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• 2004

새만금 간척사업을 둘러싸고 "개발이냐 보전이냐"에 관한 사회적 논의 이후 1998년 습지보전법을 제정한 바 있다. 그 후 갯벌의 경제적 가치에 대한 논의는 활발하지만 아직까지 우리사회는 갯벌의 일반적 가치를 제시할 만한 연구의 폭과 깊이를 확보하지 못한 상태이다. 이러한 한계를 고려하면서, 본 연구에서는 압막 - 상태 - 영향 - 반응(P - S - I - R)을 활용하여 갯벌 생태 변화를 예측한 다음 갯벌의 경제적 가치를 평가하는 것이 정책적으로 유용함을 제안한다. 한편, 우리 갯벌 가치와 관련한 선행연구결과를 검토한 결과 이를 우리 갯벌의 가치로 환산하여 일반화하기는 한계가 있음이 밝혀졌다. 이러한 한계를 감안하면서 단순평균값으로 갯벌의 가치를 도출한 결과 갯벌의 수산물생산편익은 ha당 4.994백만원, 수질정화편익은 ha당 9.757백만원의 가치를 갖는다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1998년도 학술발표회 논문집
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• pp.3-3
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• 1998

In this pressentation it is argued that the heterogeneity of a hydrologic attribute which may seem to be nonstationary at one scale, may become stationary at a larger scale. The fundamental reason for transformation from nonstationarity to stationarity whith the increase in scale is the phenomenon of coarse-graining of the hydrologic processes with increasing scale. Due to the phenomenon of aliasing, a particular scale hydrologic process heterogeneity which is observed as a nonstationary process at that scale, may be observed as a stationary process at a higher(larger) scale whose size is bigger than the stationary extent of the lower scale heterogeneity. As one goes through a hierarchical sequence of larger and larger scales for observations, one would eliminate nonstationarities which emerge at some lower scales at the expense of losing information on the high frequency fluctuations of the lower scale heterogeneities which will no longer be observed at the larger sampling scales. We call this phenimenon as the "coarse-graining in hydrologic observations". In this presentation, it is also argued that by the coarse-graining of hydrologic processes due to the averaging and aliasing operations at increasing scales, the conservation laws corresponging to these scales may still be quite parsimonious, and need not be more complicated as the scales get larger. It is shown that shen a higher(larger) scale process is formed by averaging a lower(smaller) scale process in time or space, the high frequency components of the lower scale process will be eliminated by the averaging operation. Thereby, the resuliiting average hydrologic dynamics, free from the effects of the high frequency components of the lower scale process, can still be quite simple in form. This is demonstrated by means of some recent upscaling work on the solute teansport conservation equation for hetergeneous aquifers. By means of this solute transport example, it is also shown that for the ensemble average form of a hydrologic conservation equation to be equivalent to its volume-average form at any scale, the parameter functions of that conservation equation at the immediately lower scale must be ergodic.

• 한국환경복원기술학회지
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• 제25권1호
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• pp.11-23
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• 2022

This study aims to systematically review the candidate types for OECMs suitable for domestic conditions in areas related to the Korea Forest Service in order to achieve the goal of establishing the protected areas and OECMs system required by Post-2020 GBF, and to provide basic data for the establishment of the national protected areas system. As a result of the study, the selection criteria for OECMs were presented, and it was found that arboretums·botanical gardens, Natural Recreation Forests, and air holes may correspond to the Candidate Types for OECMs. As a result of evaluating the possible areas for OECMs based on the OECMs selection criteria, in the case of arboretums·botanical gardens, it is judged that only conservation areas can be designated as OECMs, except for areas mainly used by visitors of arboretums·botanical gardens that fall under the BGCI conservation type among national and public arboretums·botanical gardens. However, private and school arboretums·botanical gardens have personal property ownership, so it was judged to have no effective measures to control activities that may adversely affect biodiversity, which showed limitations in designation of OECMs. Natural Recreation Forests was found to meet the OECMs selection criteria. However, private forests have personal property ownership, which limits the designation of OECMs. Therefore, it is necessary to strengthen the function of in-situ conservation in order to meet the OECMs for private and school arboretums·botanical gardens, and private forests that have personal property ownership. To this end, effective measures are needed to achieve biodiversity conservation outcomes, and it is judged that legal control and corresponding support policies (incentives) are needed. In the case of air holes, for sustainable conservation, the management boundary of air holes should be clearly defined based on the preparation of laws and guidelines related to air holes. In addition, it is judged that it is desirable to designate the competent local forest office as the management authority and conduct periodic detailed surveys of air holes, establish and implement the conservation plans based on those.