• 대한수학회지
• /
• 제57권6호
• /
• pp.1451-1470
• /
• 2020

We are concerned with the following elliptic equations: $$\{(-{\Delta})^s_pu={\lambda}f(x,u)\;{\text{in {\Omega}}},\\u=0\;{\text{on {\mathbb{R}}^N{\backslash}{\Omega}},$$ where λ are real parameters, (-∆)^s_p is the fractional p-Laplacian operator, 0 < s < 1 < p < + ∞, sp < N, and f : Ω × ℝ → ℝ satisfies a Carathéodory condition. By applying abstract critical point results, we establish an estimate of the positive interval of the parameters λ for which our problem admits at least one or two nontrivial weak solutions when the nonlinearity f has the subcritical growth condition. In addition, under adequate conditions, we establish an apriori estimate in L^∞(Ω) of any possible weak solution by applying the bootstrap argument.

• Steel and Composite Structures
• /
• 제24권3호
• /
• pp.297-307
• /
• 2017

A unified mathematical model of phase-lag Green-Naghdi magneto-thermoelasticty theories based on fractional derivative heat transfer for perfectly conducting media in the presence of a constant magnetic field is given. The GN theories as well as the theories of coupled and of generalized magneto-thermoelasticity with thermal relaxation follow as limit cases. The resulting nondimensional coupled equations together with the Laplace transforms techniques are applied to a half space, which is assumed to be traction free and subjected to a thermal shock that is a function of time. The inverse transforms are obtained by using a numerical method based on Fourier expansion techniques. The predictions of the theory are discussed and compared with those for the generalized theory of magneto-thermoelasticity with one relaxation time. The effects of Alfven velocity and the fractional order parameter on copper-like material are discussed in different types of GN theories.

• Smart Structures and Systems
• /
• 제18권4호
• /
• pp.707-731
• /
• 2016

A unified mathematical model of the equations of generalized magneto-thermoelasticty based on fractional derivative heat transfer for isotropic perfect conducting media is given. Some essential theorems on the linear coupled and generalized theories of thermoelasticity e.g., the Lord- Shulman (LS) theory, Green-Lindsay (GL) theory and the coupled theory (CTE) as well as dual-phase-lag (DPL) heat conduction law are established. Laplace transform techniques are used. The method of the matrix exponential which constitutes the basis of the state-space approach of modern theory is applied to the non-dimensional equations. The resulting formulation is applied to a variety of one-dimensional problems. The solutions to a thermal shock problem and to a problem of a layer media are obtained in the present of a transverse uniform magnetic field. According to the numerical results and its graphs, conclusion about the new model has been constructed. The effects of the fractional derivative parameter on thermoelastic fields for different theories are discussed.

• East Asian mathematical journal
• /
• 제31권5호
• /
• pp.743-751
• /
• 2015

In this paper, we consider a discrete ratio-dependent predator-prey system with harvesting effect. In order to investigate dynamical behaviors of this system, first we find out all fixed points of the system and then classify their stabilities by using their Jacobian matrices and local stability method. Next, we display some numerical examples to substantiate theoretical results and finally, we show numerically, by means of a bifurcation diagram, that various dynamical behaviors including cycles, periodic doubling bifurcation and chaotic bands can be existed.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제16권3호
• /
• pp.255-258
• /
• 2009

It is well known that for a sequence a = ($a_0,\;a_1$,...) the general term of the dual sequence of a is $a_n\;=\;c_0\;^n_0\;+\;c_1\;^n_1\;+\;...\;+\;c_n\;^n_n$, where c = ($c_0,...c_n$ is the dual sequence of a. In this paper, we find the general term of the sequence ($c_0,\;c_1$,... ) and give another method for finding the inverse matrix of the Pascal matrix. And we find a simple proof of the fact that if the general term of a sequence a = ($a_0,\;a_1$,... ) is a polynomial of degree p in n, then ${\Delta}^{p+1}a\;=\;0$.

• 충청수학회지
• /
• 제34권1호
• /
• pp.1-15
• /
• 2021

In the recent papers, S'anchez-Reyes [Appl. Math. Model. 40 (2016), 1676-1682] described the method for finding a minimal surface through a geodesic, and Li et al. [Appl. Math. Model. 37 (2013), 6415-6424] studied the approximation of minimal surfaces with a geodesic from Dirichlet function. In the present article, we consider an isoparametric surface generated by Frenet frame of a curve introduced by Wang et al. [Comput. Aided Des. 36 (2004), 447-459], and give the necessary and sufficient condition to satisfy both geodesic of the curve and minimality of the surface. From this, we construct minimal surfaces in terms of constant curvature and torsion of the curve. As a result, we present a new approach for constructions of the minimal surfaces from a prescribed closed geodesic and unclosed geodesic, and show some new examples of minimal surfaces with a circle and a helix as a geodesic. Our approach can be used in design of minimal surfaces from geodesics.

• East Asian mathematical journal
• /
• 제25권3호
• /
• pp.263-277
• /
• 2009

In this paper, we conduct a questionnaire survey on the actual conditions and the test on the basic scholastic ability of the students who register for the course, Introduction of Business Mathematics. We want to find the ways to improve the teaching-learning methods for this course. Especially, the registered students have difficulties in the following the course because they have not studied Calculus in their high school. So we give them several assignments on the Webwork system, an internet based homework management system, and analyze its effect on the students' scholastic achievement. And we propose a teaching-learning method suitable for the course.

• 충청수학회지
• /
• 제37권2호
• /
• pp.57-66
• /
• 2024

In this paper, we study how the Hilbert polynomial, associated with a reduced closed subscheme X of codimension 2 in ℙ^N, reveals geometric information about X. Although it is known that the Hilbert polynomial can tell us about the scheme's degree and arithmetic genus, we find additional geometric information it can provide for smooth varieties of codimension 2. To do this, we introduce the concept of Gotzmann coefficients, which helps to extract more information from the Hilbert polynomial. These coefficients are based on the binomial expansion of values of the Hilbert function. Our method involves combining techniques from initial ideals and partial elimination ideals in a novel way. We show how these coefficients can determine the degree of certain geometric features, such as the singular locus appearing in a generic projection, for smooth varieties of codimension 2.

• 한국수학사학회지
• /
• 제24권4호
• /
• pp.1-6
• /
• 2011

조선의 가장 위대한 산학자 홍정하(洪正夏)의 저서 $\ll$구일집(九一集)$\gg$(1724)에 들어있는 최소공배수를 구하는 법을 조사하여 홍정하의 수론에 대한 업적을 밝혀낸다. 홍정하는 두 자연수 a, b의 최대공약수 d와 최소공배수 l 에 대하여 l = $a\frac{b}{d}$=$b\frac{a}{d}$, $\frac{a}{d}$, $\frac{b}{d}$는 서로 소인 것을 인지하여, 자연수 $a_1,\;a_2,{\ldots},a_n$의 최대공약수 D에 대하여, $\frac{a_i}{D}$($1{\leq}i{\leq}n$)도 서로 소이고, 이들의 최소공배수 L도 서로 소인 $c_i(1{\leq}i{\leq}n)$가 존재하여 L = $a_ic_i(1{\leq}i{\leq}n)$임을 보였다. 이 결과는 조선에서 얻어낸 수론에 관한 수학적 업적 중에 가장 뛰어난 것 중의 하나이다. 홍정하가 수학적 구조를 밝혀내는 과정을 드러내는 것이 이 논문의 목적이다.

• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제24권2호
• /
• pp.325-344
• /
• 2010

본 연구는 중학생을 대상으로 학생들이 경험적 증명과 연역적 증명에 대한 선호를 결정할 때 영향을 미치는 요인을 분석하였다. 47명의 중학생에게 설문지를 통하여 자료를 수집하고 응답들을 분석한 결과, 경험적 증명과 연역적 증명의 선호에 영향을 미치는 요인들로 측정, 수학적 원리, 다양한 예를 통한 검증과정에 대한 인식들이 공통적으로 나타났다. 이 요소들은 경험적 증명과 연역적 증명의 선호와 비선호를 결정짓는 요인으로써, 선호하는 증명에 따라 상호 배타적으로 나타나지 않고 증명 선호에 영향을 미쳤다. 이를 통해 본 연구에서는 학생들이 특정 증명을 선호할 때, 한 증명에 대한 비선호와 다른 증명에 대한 선호가 동시에 작용할 수 있다는 결론과 함께 한 증명에 대한 선호요인을 보는 것만으로는 학생들의 증명 선호 이유를 정확히 파악할 수 없을 것이라는 가능성을 제언한다.