• The Korean Journal of Ecology
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• v.28 no.5
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• pp.327-333
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• 2005

For the first time in Korea, plant size, distribution pattern and root growth form of Tamarix chinensis were surveyed at natural stand in Shiwha Lake, from June to July in 2005. T, chinensis grew in the range of 350 m towards north-south and 270 m in east-west direction. The mean number of stems germinated from same root system was 1.9. On the stem base, the numbers of living and dead plants were 1,398 and 114, respectively. Mean perimeter and height of 1,398 plants were $5.9{\pm}3.2$ cm and $159{\pm}51$ cm, respectively. By dividing into 10 classes based on the perimeter size, the largest number of plants were included in the second smallest class category. However, by dividing into 10 classes on the bases of plant height, variation in the number of plants along the height showed normal distribution curve. The heights of dead plants were small in perimeter but diverse in height. On the root base, the number of plants was the greatest in the smallest size class, and conspicuously decreased with size increment. Distribution of T. chinensis was clumped pattern. Age of the largest plant was 8-year. T. chinensis had two types of root growth. One was horizontal growth in the periphery of soil surface, and the other vertical growth.

• East Asian mathematical journal
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• v.32 no.4
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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.

• Bulletin of the Korean Mathematical Society
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• v.26 no.2
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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.

• Bulletin of the Korean Mathematical Society
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• v.53 no.1
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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.

• Korean Journal of Medicinal Crop Science
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• v.15 no.5
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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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• v.1 no.2
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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.

• Korean Journal of Pharmacognosy
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• v.2 no.1
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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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• v.20 no.1
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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.

• Communications of Mathematical Education
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• v.23 no.4
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• pp.1079-1092
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• 2009

The purpose of this study is to investigate Newton's binomial theorem that was on epistemological basis of the emergent background and developmental course of infinite series and power series. Through this investigation, it will be examined how finding the approximate of square root of given numbers, the method of the inverse method of fluxions by Newton, and Gregory and Mercator series were developed in the course of history of mathematics. As the result of this study pedagogical analysis and discussion of the history of mathematics on Newton's binomial theorem will be presented.

• Structural Engineering and Mechanics
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• v.41 no.3
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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.