• 천문학논총
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• 제34권1호
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• pp.1-16
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• 2019

"Hon-Chon-Jeon-Do" is a woodcut star map with the size of $79.4cm{\times}127.5cm$, and was widely disseminated as it was made into a set with Kim, Jung Ho's "Yeoji-Jeon-Do". This study confirmed that Yixiang kaocheng xubian ("의상고성속편") star catalogue was used as a source to produce the star map, and the stereographic projection was applied with the projection center being the mid-point (Q) between the celestial and ecliptic north poles. The 'mid-circle' around the Q is arisen between the equator and the ecliptic, and on this circle, the hour angle and the ecliptic longitude of a star can be marked using the same scale. This means that the hour of the day and the season of the year can be read on the same dial of the mid-circle, and the application of this character in the practical use was the key point of the star map production. By observing either transits or positions of the 28 xiu (宿), it is easy to find the corresponding season and time by simply reading the dial on the mid-circle. This is just the function of a portable almanac and thus by disseminating it widely, the convenience of the people would have been promoted. For this reason, it can be stated that "Hon-Chon-Jeon-Do" was a practical astronomical tool which was produced by the western astronomical projection method and was used to find time and season. Choi, Han Ki and Kim, Jung Ho are strong candidates for the makers of this star map. The time of production is estimated to be 1848 ~ 1857, and "Hon-Chon-Jeon-Do" could be regarded as a good contributor to popularization of astronomy in the late Joseon Dynasty.

• 충청수학회지
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• 제13권1호
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• pp.101-107
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• 2000

For a continuous map f of the circle to itself, we show that if P(f) is closed, then ${\Gamma}(f)$ is closed, and ${\Omega}(f)={\Omega}(f^n)$ for all n > 0.

• 대한수학회논문집
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• 제15권3호
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• pp.549-553
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• 2000

For a continuous map of the circle to itself, we give necessary and sufficient conditions for the $\omega$-limit set of each nonwandering point to be minimal.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.97-99
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• 2003

Lineament density maps can be used for the quantitative evaluation of relationship between lineaments and groundwater occurrence. There are several kinds of lineament density maps including lineament length density, lineament cross-points density, and lineament counts density maps. This paper reports the usefulness of the representative elementary area (REA) concept for lineament analysis. This concept refers to the area size of the unit circle to calculate the lineament density factors distributed within the circle: length, counts and cross-points counts. The circle is a unit circle that calculates the sum of the lineament length, lineament counts and the number of cross-points within it. The REA is needed to obtain the best representative lineament density map prior to the analysis of relation between lineaments and groundwater well yield or other groundwater characteristics. A basic lineament map for the Yongsangang-Seomjingang watershed of Korea, drawn from aerial black-and-white photographs of 1/20, 000 scale was used for demonstrating the concept. From this study, the conclusions were as follows: (1) the REA concept can be efficiently applied to the lineament density analysis and mapping, (2) for whole Yongsangang-Seomjingang watershed which has 6, 502 lineaments with an average lineament length of 3.3 km, the lower limits of each REA used for drawing the three density maps were about 1.77 $\textrm{km}^2$ (r=750 m) for lineament length density, 7.07 $\textrm{km}^2$ (r=1, 500 m) for lineament counts density, and 4.91 $\textrm{km}^2$ (r=1, 250 m) for lineament cross-points density, respectively, (3) the lineament densities are inversely proportional to the size of REA, and the REA can be calculated with this inversely linear regression model, (4) if the average lineament density values for the whole study area are known, the most accurate density maps can be drawn using the REAs obtained from each linear regression model, and (5) but critical attention should be paid to draw lineament counts density and lineament cross-points density maps because.

• 수산해양기술연구
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• 제29권2호
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• pp.162-167
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• 1993

Wilbrink 본뜨기에서 모우드 라킹 현상과 소모적 궤적의 두 경우에 대한 일반화차원 D 하(n)을 수치 해석적으로 계산하였다. 투닝변수 z=0.03, 소모변수 b=0.9, k 하(d)=0.272313668의 값으로 주어진 소모적 Wilbrink 본뜨기에서 모우드 라킹현상의 경우에는 n～20일 때 D 하(-20) =0.924202의 값을 갖으며, 소모적궤적에서는 D 하(-20) =0.63292와 D 하(+20) =1.89877의 값으로 주어진다. 이때의 값들은 n$\longrightarrow$$\infty$감에 따라 Circle 본뜨기의 D 하($\pm$$\infty$) 값들과 근사적으로 일치한다.

• 대한수학회보
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• 제30권2호
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• pp.239-244
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• 1993

The purpose of this paper is to determine conditions under which equicontinuity of the family of iterates {f$^{n}$ } of a continuous function that maps the circle S$^{1}$ into itself does occur. We shall see that equicontinuity of the family of iterates {f$^{n}$ } occurs only under special cases. Actually, we will show that this happens only for rotations when degree of the function is 1, and for involutions when degree of the function is -1.

• 대한수학회보
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• 제36권4호
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• pp.707-716
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• 1999

In this pater we study the continuity of rotation numbers of liftings of circle maps with degree one. And apply our result to prove that a positively equicontinuous flow of homeomorphisms on the circle $S^1$ is topologically conjugate to a continuous flow of rotation maps.

• Korean Journal of Mathematics
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• 제8권1호
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• pp.27-32
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• 2000

In this paper, we show that for any continuous map $f$ of the circle $S^1$ to itself, (1) $x{\in}{\Omega}(f){\backslash}\overline{R(f)}$, then $x$ is not a turning point of $f$ and (2) if $P(f)$ is non-empty, then $R(f)$ is closed if and only if $AP(f)$ is closed.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제2권2호
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• pp.157-162
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• 1995

Let I be the interval, $S^1$ the circle and let X be a compact metric space. And let $C^{circ}(X,\;X)$ denote the set of continuous maps from X into itself. For any f$f\in\;C\circ(X,\;X),\;let\;P(f),\;R(f),\;\Gamma(f),\;\Lambda(f)\;and\;\Omega(f)$ denote the collection of the periodic points, recurrent points, ${\gamma}-limit{\;}points,{\;}{\omega}-limit$ points and nonwandering points, respectively.(omitted)

• 한국시스템다이내믹스연구
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• 제11권2호
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• pp.77-102
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• 2010

This paper examines a mechanism of the Electronic Territory Expansion and the Information-oriented Society. Especially, a strategy for the territory development based on intelligence is suggested. The strategy is divided into a strategy for the domestic electronic territory and a plan for the global electronic territory. To examine the strategy and the plan, this paper is using the causal map analysis based on the System Thinking Approach. The causal map of the mechanism is characterized by a positive feedback loop. The paper has concluded that it is important to make the positive loops as a virtuous circle. It means that when a society dominates the advantageous position firstly in the field of intelligent and electronic territory, the competitiveness can grow in arithmetical progression.