• 대한수학회지
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• 제44권6호
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• pp.1329-1338
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• 2007

In this paper, we study the location of zeros and Borel direction for the solutions of linear homogeneous differential equations $$f^{(n)}+A_{n-1}(z)f^{(n-1)}+{\cdots}+A_1(z)f#+A_0(z)f=0$$ with entire coefficients. Results are obtained concerning the rays near which the exponent of convergence of zeros of the solutions attains its Borel direction. This paper extends previous results due to S. J. Wu and other authors.

• 대한수학회보
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• 제33권3호
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• pp.487-496
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• 1996

Let f(z) be an entire function. Then the order $\rho(f)$ of f is defined by $$ \rho(f) = \overline{lim}_r\to\infty \frac{log r}{log^+ T(r,f)} = \overline{lim}_r\to\infty \frac{log r}{log^+ log^+ M(r,f)}, $$ where T(r,f) is the Nevanlinna characteristic of f (see [4]), $M(r,f) = max_{$\mid$z$\mid$=r} $\mid$f(z)$\mid$$ and $log^+ t = max(log t, 0)$.

• 한국환경과학회지
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• 제29권12호
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• pp.1261-1274
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• 2020

The characteristics of ammonia-nitrogen (NH4+-N) adsorption by a zeolitic material synthesized from Jeju scoria using the fusion and hydrothermal method was studied. The synthetic zeolitic material (Z-SA) was identified as a Na-A zeolite by X-ray diffraction, X-ray fluorescence analysis and scanning electron microscopy images. The adsorption of NH4+-N using Jeju scoria and different types of zeolite such as the Z-SA, natural zeolite, and commercial pure zeolite (Na-A zeolite, Z-CS) was compared. The equilibrium of NH4+-N adsorption was reached within 30 min for Z-SA and Z-CS, and after 60 min for Jeju scoria and natural zeolite. The adsorption capacity of NH4+-N increased with approaching to neutral when pH was in the range of 3-7, but decreased above 7. The removal efficiency of NH4+-N increased with increasing Z-SA dosage, however, its adsorption capacity decreased. For initial NH4+-N concentrations of 10-200 mg/L at pH 7, the adsorption rate of NH4+-N was well described by the pseudo second-order kinetic model than the pseudo first-order kinetic model. The adsorption isotherm was well fitted by the Langmuir model. The maximum uptake of NH4+-N obtained from the Langmuir model decreased in the order of Z-CS (46.8 mg/g) > Z-SA (31.3 mg/g) > natural zeolite (5.6 mg/g) > Jeju scoria (0.2 mg/g).

• 한국문헌정보학회지
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• 제32권1호
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• pp.7-26
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• 1998

이 연구에서는 타 도서관의 목록 데이터베이스를 탐색한 후 바로 원하는 자료를 요청할 수 있는 이용자 주도형 상호대차 모형을 제시하고, Z39.50 자료주문 확장서비스를 이용하는 상호대차 요청시스템을 구현하였다. 이 모형에서 이용자의 상호대차 요청은 Z39.50 확장서비스 요청 PDU를 통해 소속도서관으로 전달되며, 소속도서관과 자료의 소장도서관 사이의 상호대차 트랜잭션은 ILL 프로토콜을 이용하여 처리된다. 자료주문 확장서비스 요청 PDU의 파라미터로 ILL-REQUEST PDU를 포함시킴으로써 Z39.50 확장서비스와 ILL 프로토콜을 사용하는 두 단계의 요청과정을 효과적으로 연결할 수 있다.

• 대한수학회보
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• 제37권4호
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• pp.659-668
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• 2000

Let's $S_n(p,\alpha)(p,n\in\ N={1,2,3,\cdots},0\leq\ \alpha<1)$ denote tje c;ass pf fimctopms $f(z)=z^p+a_{p+z}z^{p+n}+\cdots$ which are $\rho$-valently starlike of order $\alpha$ in the unit disk.Some criteria for a function f(z) to be in the class $S_n(\rho,\alpha)$ are given.

• 대한수학회보
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• 제53권1호
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• pp.29-38
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• 2016

For a transcendental entire function f(z) with zero order, the purpose of this article is to study the value distributions of q-difference polynomial $f(qz)-a(f(z))^n$ and $f(q_1z)f(q_2z){\cdots}f(q_mz)-a(f(z))^n$. The property of entire solution of a certain q-difference equation is also considered.

• 대한수학회보
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• 제35권4호
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• pp.701-707
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• 1998

An operator $T{\in} {{\mathcal L}(H)}$ is generalized k-quasihyponormal if there exist a constant M>0 such that $T^{\ast k}[M^2(T-z)^{\ast}(T-z)-(T-z)(T-z)^{\ast}]T^k{\geq}0$ for some integer $k{\geq}0$ and all $Z{\in} {\mathbf C}$. In this paper, we show that it T is a generalized k-quasihyponormal operator with the property $0{\not\in}{\sigma}(T)$, then T is subscalar of order 2. As a corollary, we get that such a T has a nontrivial invariant subspace if its spectrum has interior in C.

• 대한본초학회지
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• 제31권6호
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• pp.11-20
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• 2016

Objectives : This study aims to examine validity of the following guideline for Zanthoxyli Pericarpium in the Korean Pharmacopoeia regarding foreign materials: "the seeds of Zanthoxyli Pericarpium that are mixed should not exceed 20%." Methods : Varied compliance guidelines for and original plants of Zanthoxyli Pericarpium across countries were compared and contrasted. In order to do this, pharmacopoeias from a number of different countries including Korea were used as references. Results : The weights including seed parts were Z. piperitum 3.48g, Z. schinifolium 2.94g, and Z. bungeanum 2.16g; while the weights of peel parts were Z. piperitum 1.45g, Z. schinifolium 1.69g, and Z. bungeanum 0.98g. In terms of weight, Z. piperitum was the heaviest with its entire part including the seed, whereas Z. schinifolium was the heaviest with its peel part. The proportions of each seed in the whole part were Z. piperitum 58.33%, Z. schinifolium 42.52%, and Z. bungeanum 54.63%. Considering these figures, including seed parts in the guideline up to 20% is inappropriate; however, this guideline is inevitable in order to use seed parts for medicinal purpose. Conclusion : In this article, the author argues if any changes were to made on the guideline for Zanthoxyli Pericarpium with respect to foreign materials - "the seeds of Zanthoxyli Pericarpium that are mixed should not exceed 20%" - its seed part should firsthand be separated from its peel part and be designated as one kind of medicine. Then, revisions on the foreign materials compliance guidelines for Zanthoxyli Pericarpium should also be made.

• Steel and Composite Structures
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• 제39권1호
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• pp.1-20
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• 2021

An exact solution based on refined third-order theory (TOT) has been presented for functionally graded porous curved beams having deep curvature. The displacement field of the refined TOT is derived by imposing the shear free conditions at the outer and inner surfaces of curved beams. The properties of the two phase composite are tailored according the power law rule and the effective properties are computed using Mori-Tanaka homogenization scheme. The equations of motion as well as consistent boundary conditions are derived using the Hamilton's principle. The curved beam stiffness coefficients (A, B, D) are obtained numerically using six-point Gauss integration scheme without compromising the accuracy due to deepness (1 + z/R) terms. The porosity has been modeled assuming symmetric (even) as well as asymmetric (uneven) distributions across the cross section of curved beam. The programming has been performed in MATLAB and is validated with the results available in the literature as well as 2D finite element model developed in ABAQUS. The effect of inclusion of 1 + z/R terms is studied for deflection, stresses and natural frequencies for FG curved beams of different radii of curvature. Results presented in this work will be useful for comparison of future studies.

• 대한수학회논문집
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• 제9권4호
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• pp.927-931
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• 1994

Let G be a cyclic group of order 2 and let $S^1$ denote the unit circle in $R^2$ with the standard metric. We consider smooth G-vector bundles over $S^1$ when G acts on $S^1$ by reflection. Then the fixed point set of G on $S^1$ is two points ${z_0, z_1}$. Let $E$\mid$_{z_0} and E$\mid$_{z_1}$ be the fiber G-representation spaces at $z_0$ and $z_1$ respectively. We associate an orthogonal G-representation $\rho_i : G \to O(n)$ to $E$\mid$_{z_i}, i = 0, 1$. Let det $p\rho_i(g), g \neq 1$, be denoted by det $E$\mid$_{z_i}$ since det $\rho_i(g)$ is independent of choice of $\rho_i$.