• 대한수학회보
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• 제45권1호
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• pp.169-190
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• 2008

Second-order parabolic equations with variable coefficients are considered on $\mathbb{R}^d$ and $C^1$ domains. Existence and uniqueness results are given in $L_q(L_p)$-spaces, where it is allowed for the powers of summability with respect to space and time variables to be different.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제8권1호
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• pp.71-78
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• 2001

In 1984, Johnson[A bounded convergence theorem for the Feynman in-tegral, J, Math. Phys, 25(1984), 1323-1326] proved a bounded convergence theorem for hte Feynman integral. This is the first stability theorem of the Feynman integral as an $L(L_2 (\mathbb{R}^N), L_2(\mathbb{R}^{N}))$ theory. Johnson and Lapidus [Generalized Dyson series, generalized Feynman digrams, the Feynman integral and Feynmans operational calculus. Mem, Amer, Math, Soc. 62(1986), no 351] studied stability theorems for the Feynman integral as an $L(L_2 (\mathbb{R}^N), L_2(\mathbb{R}^{N}))$ theory for the functional with arbitrary Borel measure. These papers treat functionals which involve only a single integral. In this paper, we obtain the stability theorems for the Feynman integral as an $L(L_1 (\mathbb{R}^N), L_{\infty}(\mathbb{R}^{N}))$theory for the functionals which involve double integral with some Borel measures.

• 영어어문교육
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• 제10권2호
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• pp.1-23
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• 2004

This article reports a bi-directional interlanguage study designed to investigate the initial state of L2 acquisition with regard to English and Korean wh-questions. Based on the UG system in line with the minimalist theory, it was hypothesized that the L2 initial state is characterized by the most economical form of syntax in which no overt wh-movement to Spec-CP is assumed. Results of the early interlanguage study showed that 1) L1 Korean learners of L2 English predominantly produced wh-questions with the fronted wh-word, but without productive wh-movement to the Spec-CP position; and 2) L1 English learners of L2 Korean overwhelmingly produced wh-questions with the wh-word remaining in-situ. These results were interpreted as supporting the minimalist account of the L2 initial grammar in that no overt syntactic wh-movement were adopted in early interlanguages of both English and Korean regardless of the learner's L1.

• 대한수학회지
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• 제37권3호
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• pp.359-369
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• 2000

Let X be an integral Gorenstein projective curve with g:=pa(X) $\geq$ 3. Call $G^r_d$ (X,**) the set of all pairs (L,V) with L$\epsilon$Pic(X), deg(L) = d, V $\subseteq$ H^0$(X,L), dim(V) =r+1 and V spanning L. Assume the existence of integers d, r with 1 $\leq$ r$\leq$ d $\leq$ g-1 such that there exists an irreducible component, , of $G^r_d$(X,**) with dim($\Gamma$) $\geq$ d - 2r and such that the general L$\geq$$\Gamma$ is spanned at every point of Sing(X). Here we prove that dim( ) = d-2r and X is hyperelliptic.

• Journal of applied mathematics & informatics
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• 제20권1_2호
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• pp.479-483
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• 2006

For any fixed $\lambda\leq-\frac{1}{2}$, there exists $f(\eta){\in}C^1[0,+\infty)$ which satisfies the following nonlinear boundary value problem f'+ff'+$\lambda(l-f'^2)=0$ a.e.in $(0,+\infty)$, f(0)=0, f'(0) = 0, $f'(+\infty)=1$, which arises in boundary layer theory in fluid mechanics.

• 한국수학사학회지
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• 제24권4호
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• pp.1-6
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• 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.

• 물과 미래
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• 제19권2호
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• pp.131-138
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• 1986

단일유공벽의 수리학적 특성 및 동력학적 특성에 대해서 이론 및 실험적으로 연구하였다. 굴구의 이론식을 응용하여 연구한 바에 의하면 산란파항은 파력에 거의 영향을 주지 못함을 알 수 있고 실험에 의한 연구에 의하면 유공율의 변화에 따른 파력의 거동은 매우 민감한 것으로 나타났지만 구멍의 지름에 대한 벽두께의 비(l/D)는 좀 특이한 현상을 보인다. l/D의 값이 작은 범위에서는 유공벽의 구멍을 orifice라고 할 수 있으므로, 파력이 l/D의 변황에 거의 영향을 받지 않고, 이 때의 에너지 손실계수는 굴구의 식을 이용하면 1.0으로 나타난다. 그러나 l/D의 값이 큰 범위에서는 구멍내의 흐름을 관수로의 흐름이라고 볼 수 있으므로 파력이 l/D에 민감하고 이 때의 f는 1.5로 나타났다.

• 대한수학회보
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• 제36권1호
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• pp.171-181
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• 1999

In this note, we will prove that the operator-valued function space integral as an operator from $L_p\;to\;L_{p'}$ (1

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.620-620
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• 2013

When $MoS_2$ is thinned to single layer (1L), photoluminescence (PL) quantum yield drastically increases due to emergence of direct band gap. A recent theory predicts that the electronic structure of 1L $MoS_2$ is very sensitive to its lattice constants. We investigated the response of 1L $MoS_2$ to biaxial tensile strain using spatially resolved PL and Raman spectroscopy. Changes in the lattice constants were monitored by the Raman frequency of the in-plane ($E^1{_2g}$) mode. Systematic correlations between PL and Ramanspectral features, revealed in the preliminary results, will be further tested with samples on other substrates and against thermal stress. The results will also be discussed in regard to the theory which predicts that 1L $MoS_2$ becomes an indirect semiconductor at small tensile strain and turns metallic when further extended.

• Educational Technology International
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• 제13권1호
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• pp.1-25
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• 2012

Despite the relatively short history of Social Network Sites or Services (SNS), it has quickly gained popularity with more than seven hundred million users all over the globe. The SNS emerged as one of the strongest cultural influences for the contemporary society. The SNS would provide both chances and challenges for Education. The main purpose of the article was to explore the way education react and adapt to the emergence of social network and SNS. It tried to provide major theoretical grounds that bridge education and social network. In the due process, the researchers have examined the curriculum and instructional design process of education from the perspective of disruptive and sustainable aspect of SNS technology. Consequently, four major theoretical grounds were identified and reviewed: Gibson's theory of affordance, Vygotsky's social constructivism, Rha's human visual intelligence theory, and the network theory. By investigating these theories, the educational potentials of social network and SNS were emerged. The SNS was viewed as a new medium with abundant potentials of expanding the learning space, empowering the affective aspects of learning, and facilitating the formation of group intelligence. Finally, some future implications and challenges of SNS were suggested.