• The Korean Journal of Ecology
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• 제28권5호
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• pp.327-333
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• 2005

시화호 내 형성된 위성류 자연 군락의 개체군 특성을 밝히기 위해 매목의 크기, 공간분포 및 뿌리의 생장형태를 국내 최초로 조사하였다. 위성류 군락은 남북으로 약 350 m, 동서로 270 m 범위에 형성되어 있었다. 동일한 뿌리로부터 발생한 줄기는 평균 1.9개이었는데 지면에서 갈라진 줄기를 각각의 개체로 간주하였을 때(줄기 기준) 살아있는 개체는 총 1,398개체이었으며 고사한 것은 114개체로 총 1,512개체가 조사되었다. 지면으로부터 20 cm높이에서의 평균둘레는 $5.9{\pm}3.2$ cm, 평균높이는 $159{\pm}51$ cm이었다. 개체의 둘레 크기를 10계급으로 구분한 결과 두번째로 작은 계급의 개체수 가장 많았으며 크기가 증가할수록 개체수가 감소하였다. 그러나 높이 크기를 10계급으로 구분한 결과는 정규분포에 가까운 형태를 나타냈다. 고사한 개체는 둘레 크기에는 작은 계급에 속하였으나 높이의 크기에서는 상위 2계급만 제외하고 전 계급에 분포하였다. 동일한 지하부를 갖고 있는 개체를 하나로 간주하였을 경우(뿌리 기준) 20 cm 높이에 서의 면적을 10계급으로 구분한 결과 가장 작은 크기의 개체가 대부분을 차지하였고(83.8%), 크기가 증가할수록 개체수가 현저히 감소하였다. 위성류 매목은 군락의 중심에 집중분포를 하였으며 상대적으로 남북 방향이 동서방향보다 더욱 심한 집중분포의 경향을 보였다. 가장 큰 매목의 수령은 8년이었다. 위성류 뿌리의 생장형태는 크게 두 가지인데 하나는 지표면 근처에서 수평 방향으로, 다른 하나는 수직 방향으로 생장하고 있었다.

• East Asian mathematical journal
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• 제32권4호
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• pp.545-563
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• 2016

The aim of this study was to observe processes and implication to a given program for the 20 gifted children grade 5 by making the number from 1 to 100 with natural numbers 4,4,9 and 9. Revelation of creativity, mathematical tendency of students and meaningful responses were observed by the qualitative records of this game activity and the analysis of result. The major result of a study is as follows: The mathematical creativities of students were revealed and developed by this activity. And the mathematical attitude were changed and developed, so student could actively participate. And students could experience collaborative and social composition learning by presentations and discussion, competition with a permissive atmosphere and open-game rule. It was meaningful that mathematical ideas (negative number, square root, factorial, [x]: the largest integer not greater than x, absolute value, percent, exponent, logarithm etc.) were suggested and motivated by students themselves.

• 대한수학회보
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• 제26권2호
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• pp.151-158
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• 1989

Let (H, B, .nu.) be an abstract Wiener space where H is a separable Hilbert space with the inner product <.,.> and the norm vertical bar . vertical bar=.root.<.,.>, which is densely and continuously imbedded into a separable Banach space B with the norm ∥.∥ , and .nu. is a probability measure on the Borel .sigma.-algebra B(B) of B which satisfies (Fig.) where $B^{*}$ is the topological dual of B and (.,.) is the natural dual pairing between B and $B^{*}$. We will regard $B^{*}$.contnd.H.contnd.B in the natural way. Thus we have =(y, x) for all y in $B^{*}$ and x in H. Let $R^{n}$ and C denote the n-dimensional Euclidean space and the complex numbers respectively.ctively.

• 대한수학회보
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• 제53권1호
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• pp.1-20
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• 2016

The general number field sieve (GNFS) is asymptotically the fastest known factoring algorithm. One of the most important steps of GNFS is to select a good polynomial pair. A standard way of polynomial selection (being used in factoring RSA challenge numbers) is to select a nonlinear polynomial for algebraic sieving and a linear polynomial for rational sieving. There is another method called a nonlinear method which selects two polynomials of the same degree greater than one. In this paper, we generalize Montgomery's method [12] using geometric progression (GP) (mod N) to construct a pair of nonlinear polynomials. We also introduce GP of length d + k with $1{\leq}k{\leq}d-1$ and show that we can construct polynomials of degree d having common root (mod N), where the number of such polynomials and the size of the coefficients can be precisely determined.

• 한국약용작물학회지
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• 제15권5호
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• pp.315-318
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• 2007

An effective rapid propagation method was established through in vitro cultures of the medicinal plant, Cudrania tricuspidata. In vitro plantlets were obtained from in vitro germinated seeds. The various levels of cytokinins (BAP, Kinetin and TDZ) were tested on multiple shoot formation from plantlets. BAP (1.0 mg/l) treatment induced highest number of multiple shoots. Single shoot cultures gave higher initial shoot numbers than 5 shoots per culture. Among the various culture media, the shoot elongation was optimal on 2 MS basal medium without growth regulators. The IAA (2.0 mg/l) treatment induced highest number of roots. IBA (2.0 mg/l) treatment more promoted in vitro root growth than other concentrations. Rooted shoots were transferred directly to small pots with an artificial soil and successfully acclimatized.

• Plant Resources
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• 제1권2호
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• pp.109-112
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• 1998

Aloe in vitro culture was attempted to induce callus and regeneration ability from different explant sources onto MS medium with 0.5mg/l NAA plus 1.0mg/l BA. Anthers that no developed any callus and plant regeneration, while only four out of 274 filament explants induced calli at cut edge without regenerated plants. Twenty ovary explants regenerated four direct plantlets without via callus from the base of epidermal tissues. Regenerated plants on the root tip gave 2n=14 of chromosome numbers.

• 생약학회지
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• 제2권1호
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• pp.29-34
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• 1971

A comparative study on Angelica and Cnidium, the two genera of Umbelliferae growing in Korea, was carried about the cytology and fertility of pollen. The somatic chromosome number of Umbelliferae was found almost to be 2N=22. Both species of Kang-whal and Chun-gung were found to be in polyploid with different chromosome numbers each other. The pollen fertility among the species of Angelica was high, but Toh-chun-gung was zero percent. The species of Angelica have been generated with pollen fertility, but species of Cnidium with only root or rootlet.

• Journal of Biosystems Engineering
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• 제20권1호
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• pp.66-72
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• 1995

A numerical study for a two dimensional multi-impingement jet with crossflow of the spent fluid has been carried out. To study the flow characteristics especially in the jet flow region, three different distributions of mass flow rate at 5-jet exits were assumed. For each distribution, various Reynolds numbers ranging from laminar to turbulent flows were considered. Calculations drew the following items as conclusion. 1) A periodical fully developed flow was observed from the third protrusion. This was also observed from previous experimentally by Whidden at al. The Nessult number at the protrusion surface increased mildly as going downstream. 2) The low Reynolds number turbulence model of Launder and Sharma was found to be adequate for the prediction of fluid flow and heat transfer characteristics of two dimensional multi-jet configuration. 3) The Nusselt number at the protrusion surface was nearly proportional to the square root of the Reynolds number.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제23권4호
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• pp.1079-1092
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• 2009

본 연구는 무한급수와 멱급수의 발생 배경과 발달 과정의 인식론적 토대가 되었던 뉴턴의 이항정리(binomial theorem)의 개념을 살펴보고, 그 발달 과정에서 얻어진 제곱근의 근삿값 구하는 방법, 뉴턴의 역유율법을 이용한 정적분 구하는 방법, 그리고 메르카토어 급수와 그레고리 급수의 발견 과정을 알아보고자 한다. 이 과정을 통하여 뉴턴의 이항정리가 가지는 수학사의 교수법적 논의를 제시하고자 한다.

• Structural Engineering and Mechanics
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• 제41권3호
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• pp.349-363
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• 2012

Fuzzy logic based control has recently been proposed for regulating the properties of magnetorheological (MR) dampers in an effort to reduce vibrations of structures subjected to seismic excitations. So far, most studies showing the effectiveness of these algorithms have focused on the use of a single MR damper. Because multiple dampers would be needed in practical applications, this study aims to evaluate the effects of multiple individually tuned fuzzy-controlled MR dampers in reducing responses of a multi-degree-of-freedom structure subjected to seismic motions. Two different fuzzy-control algorithms are considered, a traditional controller where all parameters are kept constant, and a gain-scheduling control strategy. Different damper placement configurations are also considered, as are different numbers of MR dampers. To determine the robustness of the fuzzy controllers developed to changes in ground excitation, the structure selected is subjected to different earthquake records. Responses analyzed include peak and root mean square displacements, accelerations, and interstory drifts. Results obtained with the fuzzy-based control schemes are compared to passive control strategies.