• Korean Journal of Mathematics
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• 제16권3호
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• pp.259-269
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• 2008

The non-existence and existence of the positive solution for the generalized cooperation biological model for two species of animals $${\Delta}u+u(a-bu+g(v))=0\;in\;{\Omega}\\{\Delta}v+v(d+h(u)-cv)=0\;in\;{\Omega}\\u=v=0\;on\;{\partial}{\Omega}$$ are investigated. The techniques used in this paper are elliptic theory, upper-lower solutions, maximum principles and spectrum estimates. The arguments also rely on some detailed properties for the solution of logistic equations.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제12권3호
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• pp.169-178
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• 2005

In this paper we study the existence and local asymptotic limit of the topological Chern-Simons vortices of the CP(1) model in $\mathbb{R}^2$. After reducing to semilinear elliptic partial differential equations, we show the existence of topological solutions using iteration and variational arguments & prove that there is a sequence of topological solutions which converges locally uniformly to a constant as the Chern­Simons coupling constant goes to zero and the convergence is exponentially fast.

• 물과 미래
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• 제23권3호
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• pp.319-328
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• 1990

2차원 하구모델의 매개변수 동정을 BF좌표계로 변환된 ADI-FDM출력 수치모형을 사용하여 수행하였다. 모형에서 기본 방정식을 동수역학식과 수송방정식이 복합된 방정식을 사용하였다. Thompson식이 지배방정식을 사각평면으로 변환 하는데 사용도이ㅓㅆ으며 Thompson의 Elliptic 격자발생기법이 BF 좌표계에서 곡선격자망을 발생하는데 사용되었다. 지배방정식에서 동정될 매개변수는 마찰계수와 분산 정수이다. 출력수치모형은 BF좌표계에서 조석평균 염도 모형이 사용되었다. 최적화 기법으로 영향계수 알고리즘을 적용하였다. 또한 Lumped 모형이 동정에 고려 되었다. 본 연구는 새로운 출력 수치모형이 하구염도 모형의 매개변수 동정에 있어 유용한가를 검토 하는데 중점을 두었다. 제안된 기법은 간단한 가상모형에 실험적인 적용을 통하여 검토되었다. 검토한 결과는 제안된 기법이 하구모형에서 매개변수 동정시 도입될 수 있음을 보여주었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.651-654
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• 2005

In this paper, we designed ECC(Elliptic Curve Cryptographic) Processor with Bus-splitting mothod for embedded SoC. ECC SIP is designed by VHDL RTL modeling, and implemented reusably through the procedure of logic synthesis, simulation and FPGA verification. To communicate with ARM9 core and SIP, we designed SIP bus functional model according to AMBA AHB specification. The design of ECC Processor for platform-based SoC is implemented using the design kit which is composed of many devices such as ARM9 RISC core, memory, UART, interrupt controller, FPGA and so on. We performed software design on the ARM9 core for SIP and peripherals control, memory address mapping and so on.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.729-739
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• 2017

The objective of this study was to optimize minimum-energy impulsive spacecraft intercept using genetic algorithms. A mathematical model was established on two-body system based on f and g solution and universal variable to address spacecraft intercept problem for non-coplanar elliptical orbits. This nonlinear problem includes many local optima due to discontinuity and strong nonlinearity. In addition, since it does not provide a closed-form solution, it must be solved using a numerical method. Therefore, the initial guess is that a very sensitive factor is needed to obtain globally optimal values. Genetic algorithms are effective for solving these kinds of optimization problems due to inherent properties of random search algorithms. The main goal of this paper was to find minimum energy solution for orbit transfer problem. The numerical solution using initial values evaluated by the genetic algorithm matched with results of Hohmann transfer. Such optimal solution for unrestricted arbitrary elliptic orbits using universal variables provides flexibility to solve orbit transfer problems.

• 대한수학회논문집
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• 제10권1호
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• pp.39-48
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• 1995

The ADI method was introduced by Peaceman and Rachford [6] in 1955, to solve the discretized boundary value problems for elliptic and parabolic PDEs. The finite difference discretization of the model elliptic problem $$ (1) -\Delta u = f, \Omega = [0, 1] \times [0, 1] $$ $$ u = 0 on \delta \Omega $$ with 5-point centered finite difference discretization, with n +2 mesh-points in the x - direction and m + 2 points in the y direction, leads to the solution of a linear system of equations of the form $$ (2) Au = b $$ where A is a matrix of dimension $N = n \times m$. Without loss of generality and for the sake of simplicity, we will assume for the remainder of this paper that m = n, so that $N = n^2$.

• 대한수학회논문집
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• 제17권2호
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• pp.349-361
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• 2002

The ill-posed elliptic wave propagation problems can be transformed into well-posed initial value problems of the reflection and transmission operators characterizing the material structure of the given model by the combination of wave field splitting and invariant imbedding methods. In general, the derived scattering operator equations are of first-order in range, nonlinear, nonlocal, and stiff and oscillatory with a subtle fixed and movable singularity structure. The phase space and path integral analysis reveals that construction and reconstruction algorithms depend crucially on a detailed symbol analysis of the scattering operators. Some information about the singularity structure of the scattering operator symbols is presented and analyzed in the transversely homogeneous limit.

• 한국정보통신학회논문지
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• 제6권2호
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• pp.200-206
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• 2002

곡률을 .가진 산란체의 전자파 해석에 유용한 선조합 모델링 기법을 제안한다. 곡률을 가진 2차원 타원형 실린더를 기준으로 곡률 정보가 포함된 선전류에 의해 선조합 모델링한다. 본 논문에서 제안한 선조합 모델링 기법의 우수성은 도체 내부 전계의 크기로 확인하였고, 수치 해석 곁과 기존의 동일 반지름에 의한 방법보다 본 방법은 선전류의 개수를 줄일 수 있을 뿐만 아니라 모멘트법 해의 정확성을 높일 수 있다.

• 한국해안해양공학회지
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• 제6권3호
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• pp.260-265
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• 1994

대규모 흐름이 존재하는 불규칙한 해역에서 새로운 타원형 파동방정식을 유도하고, 유한차분법을 이용한 효율적인 수치모형을 개발하였다. 이때 청원형 방정식은 초기식 문제의 해법과 유사한 방법을 사용하여 해를 구하였다. 이 방법은 불규칙파의 변형을 계산하는 데 특히 효과적이며 수리모형 실험결과(Hiraishi, 1991)와 잘 일치하였다. 마지막으로 수중천퇴가 존재하는 완경사 해역에서 파랑과 흐름의 상호작용에 의한 수치해를 예시하였다.

• Steel and Composite Structures
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• 제36권1호
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• pp.87-101
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• 2020

A multi-scale epoxy/CNT/fiberglass annular sector plate is studied in this paper in the view of determining nonlinear forced vibration characteristics. A 3D Mori-Tanaka model is employed for evaluating multi-scale material properties. Thus, all of glass fibers are assumed to have uni-direction alignment and CNTs have random diffusion. The geometry of annular sector plate can be described based on the open angle and the value of inner/outer radius. In order to solve governing equations and derive exact forced vibration curves for the multi-scale annular sector, Jacobi elliptic functions are used. Obtained results demonstrate the significance of CNT distribution, geometric nonlinearity, applied force, fiberglass volume, open angle and fiber directions on forced vibration characteristics of multi-scale annular sector plates.