• Korean Journal of Environment and Ecology
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• v.6 no.2
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• pp.134-146
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• 1993

A survey of the Chundong valley forest in Mt. Sobaek was conducted using 20 sample plots of 500$m^2$ size. The classification by TWINSPAN and DCA, CCA ordination techniques were applied to the study area in order to classify them into several groups based on woody plants and environmental variables. By TWINSPAN techniques, the plant community were divided into four groups. The dividing groups are Pinus densiflora community, Qurcus variabilis -Q. mongolica -P. densiflora community, Fraxinus rhynchophylla community. The successional trends of tree species by DCA ordination techniques and DBH class distribution analysis seems to be from P. densiflora through Q. mongolica. Q. variabilis to F rhynchophylla. The correlation between the score of first two axes and soil pH, soil humus, soil calcium concentration, soil magnesium concentration was significantly positive in CCA ordination. The positive correlation between the score of first two axes of F. rhynchophylla community and soil humus, soil magnesium concentration and between ones of P. densiflora community and soil pH were calculated. But there is no correlation between species and environmental variables.

• Bulletin of the Korean Mathematical Society
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• v.57 no.4
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• pp.991-1002
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• 2020

We show that when n > m, the following delay differential equation fⁿ(z)f'(z) + p(z)(f(z + c) - f(z))^m = r(z)e^q(z) of rational coefficients p, r doesn't admit any transcendental entire solutions f(z) of finite order. Furthermore, we study the conditions of α₁, α₂ that ensure existence of transcendental meromorphic solutions of the equation fⁿ(z) + f^n-2(z)f'(z) + P_d(z, f) = p₁(z)e^α₁(z) + p₂(z)e^α₂(z). These results have improved some known theorems obtained most recently by other authors.

• Korean Journal of Environment and Ecology
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• v.24 no.6
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• pp.708-722
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• 2010

This study was carried out to classify vegetation structure of the Hyangjeokbong in the Deogyusan National Park using the gradient analysis and phytosociological method. The vegetation was classified into Quercus mongolica community(Rhododendron schlippenbachii subcommunity, typical subcommunity), Q. serrata community, Q. variabillis community, Pinus densiflora community, Cornus controversa community, Fraxinus mandshurica community and Taxus cuspidata community. Ecological characteristics such as species composition, layer structure, vegetation ratio, and the distribution of individual trees by DBH(diameter at breast height) were significantly different among communities. The order of important value of the forest community with DBH 2cm above plants was Q. mongolica(81.2), F. mandshurica, Q. serrata, P. densiflora, Acer pseudosieboldianum, Q. variabillis, Rhododendron schlippenbachii, C. controversa, T. cuspidata. Distribution of DBH of Q. mongolica and Q. serrata had suggesting a continuous domination of these species over the other species for the time being. In contrast, F. mandshurica appeared limited to the valley of the sheet and a higher frequency of young individuals, suggesting a continuous domination of these species the development of a climax forest terrain. P. densiflora and T. cuspidata had suggesting a continuous domination of these species over the other species for the time being in maintain. Q. variabilis and C. controversa had a formality distribution, suggesting a continuous domination of these species over the other species for the time being. This study examined the correlation between each community and the environment according to DCCA ordination. The Q. mongolica community and T. cuspidata community predominated in the highest elevation habitats which had few moisture, Ca and in the low pH. The Q. serrata community mainly occurred in the low elevation habitats which had many moisture. P. densiflora community predominated in the middle elevation and south-facing slope habitats which had few moisture, Ca and in the low pH. F. mandshurica community predominated in the low elevation habitats which had many moisture, Ca and pH.

• Bulletin of the Korean Mathematical Society
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• v.40 no.3
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• pp.489-501
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• 2003

In this paper we shall consider the nonlinear delay difference equation $\Delta({p_n}{\Deltax_N})\;+\;q_nf(x_{n-\sigma})\;=\;0,\;n\;=\;0,\;1,\;2,\;...$ when (equation omitted). We will establish some sufficient conditions which guarantee that every solution is oscillatory or converges to zero.

• Journal of Korean Library and Information Science Society
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• v.36 no.2
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• pp.197-220
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• 2005

This paper examined the structure of internet bookstore users' subjectivity by focusing on their beliefs, values and attitudes.0 methodology was utilized for the study. After constituting 36 Q sample and 28 P sample, data were collect from April 15, 2005 to April 22 2005. The analyses showed 3 types of subjectivity structures. The first one was 'the economic benefit-seeking type.' Those in this type were motivated to use internet bookstores to achieve economic benefits. They paid more attention to the Prices discounted than the web site contents provided by internet bookstores. This type was conspicuously found among college students. The second one was the 'information-seeking type.' People in this category made visits to internet bookstores in order to obtain new information or professional materials. This type was dominantly found among women. The third one was the 'convenience-seeking type.' Those in this type were concerned not only with the accessibility and convenience, but also with such practical issues as delivery, price, applicability, payment, and bonus. This type was conspicuously observed among white collar workers. These findings suggests that in order to make internet bookstores more attractive to users, it is demanded to understand various needs held by users and map out sophisticated marketing strategies on the basis of such a knowledge.

• Kyungpook Mathematical Journal
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• v.57 no.2
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• pp.251-263
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• 2017

The aim of this paper is to investigate the dynamical behavior of the difference equation $$x_{n+1}={\frac{{\alpha}x_n}{{\beta}+{\gamma}x^p_{n-1}x^q_{n-2}}},\;n=0,1,{\ldots}$$, where the parameters ${\alpha}$, ${\beta}$, ${\gamma}$, p, q are non-negative numbers and the initial values $x_{-2}$, $x_{-1}$, $x_0$ are positive numbers. Also, some numerical examples are given to verify our theoretical results.

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.267-276
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• 2017

The purpose of this paper is to investigate the local asymptotic stability of equilibria, the periodic nature of solutions, the existence of unbounded solutions and the global behavior of solutions of the fractional difference equation $$x_{n+1}=\frac{^{{\alpha}x}n-1(k+1)}{{\beta}+{\gamma}x^p_{n-k}x^q_{n-(k+2)}}$$, $$n=0,1,{\dots}$$ where the parameters ${\alpha}$, ${\beta}$, ${\gamma}$, p, q are non-negative numbers and the initial values $x_{-(k+2)}$,$x_{-(k+1)}$, ${\dots}$, $x_{-1}$, $x_0{\in}\mathb{R}^+$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.1-1
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• 2010

In this study, electrical properties of multilayer piezoelectric transformer sintered at $900^{\circ}C$ using pure Ag internel electrode was investigated. This multilayer piezoelectric transformer was fabricated as a ring-dot type. The multilayer piezoelectric transformer should have hight electromechanical coupling factor ($k_p$) and electromechanical qualiy factor ($Q_m$) in order to increase the efficiency of energy conversion between electrical and mechanical energy. The maximum values of $k_p$ and $Q_m$ showed 0.552 and 1320, respectively.

• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.37-44
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• 1993

The collapse of four domestic Fagaceae species was observed in relation with their moisture content(MC), basic density, P (Percent of moisture content saturation of the wood) and Q (Percent of cell cavity volume containing water) and the variation of collapse phenomenon in the cross section of stem was also investigated. The results were summarized as follows : The values of collapse in each species were great in order of Quercus dentata, Quercus variabilis, Quercus aliena and Quercus mongolica and the values were higher in heartwood than in sapwood in all of specimen. MC, basic density, P and Q were important factors which affected on the occurance of collapse and the collapse phenomenon was decreased from pith to bark.

• Communications of the Korean Mathematical Society
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• v.25 no.3
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• pp.385-389
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• 2010

In 1997, Exton, by mainly employing a widely-used process of resolving hypergeometric series into odd and even parts, obtained some new and interesting summation formulas with arguments 1 and -1. We aim at showing how easily many summation formulas can be obtained by simply combining some known summation formulas. Indeed, we present 22 results in the form of two generalized summation formulas for the generalized hypergeometric series $_4F_3$, including two Exton's summation formulas for $_4F_3$ as special cases.