• Korean Journal of Crystallography
• /
• v.12 no.1
• /
• pp.31-36
• /
• 2001

결정학의 핵심 과제는 위상(phase) 문제의 해결이다. 이 위상 묹를 해결하는 한 방법으로 요즘의 고속 컴퓨터를 사용하는 시행착오법(trial and error method)을 가상해 볼 수 있다. 간단한 예를 들면, centrosymmetric인 삼사정계(triclinic system)에 속한 비교적 작은 유기화합물인 경우, 전형적으로 3000개 정도의 회절 강도가 측정된다. Centrosymmetric 공간군(space group)의 구조 인자(structure factor)는 위상이 0°이거나 180°이기 때문에, 구조 인자는 "+"이거나 "-"부호를 가지므로 3000개 각각에 두 가지 부호를 배당할 수 있다. 이 3000개의 부호를 조합할 수 있는 개수는 2/sup 3000/개로 이 개수만큼의 Fourier 지도들을 작도하면 그 중의 하나는 옳은 것이다. Fourier 지도 한 개를 작도하는데 1분이 소요된다고 가정하면, 이들을 모두 계산하는데 2/sup 2981/년의 계산 시간이 소요된다. (참고로 2/sup 10/=1084). 따라서 시행착오법으로는 도저히 불가능함을 알 수 있다. 더구나, noncentrosymmetricc 공간군에서는 더욱 어렵게 된다. 그리하여 위상 문제를 해결하려는 많은 시도가 행해졌는데, 그것들 중의 하나가 Patterson 방법이다.

• The Mathematical Education
• /
• v.15 no.2
• /
• pp.15-18
• /
• 1977

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.6
• /
• pp.785-791
• /
• 2021

In this paper, we propose a methodology for estimating the optimal traversable destination from the location-based information of the object recognized by the mobile robot to perform the object delivery service. The location estimation process is to apply the generalized Voronoi graph to the grid map to create an initial topology map composed of nodes and links, recognize objects and extract location data using RGB-D sensors, and collect the shape and distance information of obstacles. Then, by applying the hybrid approach that combines the center of gravity and thinning method, the optimal moving position for the service robot to perform the task of grabbing is estimated. And then, the optimal node information for the robot's work destination is updated by comparing the geometric distance between the estimated position and the existing node according to the node update rule.

• Communications of Mathematical Education
• /
• v.15
• /
• pp.23-28
• /
• 2003

실수계와 n-차원 벡터 공간을 대수적 특성, 순서적 특성 그리고 위상적 특성을 중심으로 전개하고, 실변수 실가 함수와 n-차원 벡터 공간을 정의역으로 하는 실가함수를 연속성 (미분가능성), 단조성 그리고 볼록성을 중심으로 내용을 다룬다. 특히 실생활과 관련하여 이론을 전개하여 학습을 지도할 수 있는 교육과정을 개발하고, 직관적인 사고와 수리 논리적인 사고의 적절한 배합을 통해 학습자들이 적극적으로 학습에 임할 수 있는 교수 학습 방법을 개발하는 것을 목적으로 한다.

• Journal of Korean Society for Geospatial Information Science
• /
• v.7 no.1 s.13
• /
• pp.41-52
• /
• 1999

In order to correct mismatches between neighboring digital maps, the middle line method has been widely used. However, it may result in not only a corruption of the topological consistency between the objects near to boundaries but also degeneration of accuracy. In this paper, we propose two edge-matching methods to overcome the problem of the middle line method. The first method is based on the rubber sheeting, which performs an elastic transformation for the objects located around the boundaries. The second method transforms the geometry of objects by the function of the distance from the boundary. These methods have important advantages that they preserve the topology of the original maps and improve tile accuracy, compared with the previous methods.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.12 no.1
• /
• pp.43-52
• /
• 1994

This paper outlines a new approach to the line generalization when preparing small scale map on the basis of existing large scale digital map. Line generalizations are conducted based on Douglas algorithm using 1/25,000 scale topographic maps of southeastern JEJU island which produced by National Geographic Institute to analyze the fitness to the original and problems of graphical representation. Compare to the same scale map which was generated by manual method, a verity of small, but sometimes significant errors ＆ modification of topological relationship have been detected. The research gives full details of three algorithms that operationalize the smallest visible object method, together with some empirical results. A comparison of the results produced by the new algorithms with those produced by manual generalization and Douglas method of data reduction is provided. Also this paper presents the preliminary results of an relationships between the size of smallest visual object and requiring data storages for each algorithms.

• Journal of the Korean association of regional geographers
• /
• v.15 no.1
• /
• pp.86-98
• /
• 2009

Han-Ki Choi($1803{\sim}1877$), who was a scholar in Joseon dynasty, understood geography into a synthetic category of chorography, cartography, earth science and fengshui. He focused on chorography and map as a leading position in geography. The purpose of the research of Han-Ki Choi was to examine the way of Heaven, and then to make clear the way of Humanity. The identity of the geography for Han-Ki Choi was a practical science that useful for the ruling over the country and the welfare of people. He emphasized the nature of relationship with humans in geography. The system of Han-Ki's Chi-hak came from the basis of a geography, on the contrary, his geographical works were accomplished on the ground of the Chi-science. The chorography, Chi-hak of the earth and the earth science were composed into systematic organization for achieving the goal of the Chi-geography.

• Journal of The Korean Association For Science Education
• /
• v.35 no.2
• /
• pp.289-301
• /
• 2015

This study noted that elementary school students were unable to accurately comprehend the principles of moon phase changes and that teachers themselves lacked a full understanding of it as well. Therefore, this study classifies conception types through 161 5th grade respondents and suggests how to change students' conception types through the use of reconstructed teaching and learning materials (that have been developed in existing studies). It verified the changes in the learning achievement of 129 5th grade respondents and analyzed how to think about reconstructed teaching and learning materials through four teacher respondents and four 5th grade respondents from the same study. The results of this study are as follows: First, the conception types on moon phase changes were classified into C and W types. W types consisted of W1, W2, W3, W4, and W5 types. Students had difficulty in understanding the principles of a waxing crescent moon and first quarter phase changes. Second, the group taking classes, which implemented reconstructed teaching and learning materials, showed greater improvement in learning achievement posttest and long-term tests compared to those who have not. Finally, teachers and students reacted positively to the reconstructed teaching and learning materials as shown in exit survey results. In conclusion, it is suggested that teachers are better off utilizing reconstructed teaching and learning materials so that elementary school students may fully understand the principles of moon phase changes rather than just memorizing the results.

• Journal of Korean Society for Geospatial Information Science
• /
• v.17 no.1
• /
• pp.149-155
• /
• 2009

To quantitatively analyze the positioning error due to the ionosphere over the Korean peninsula, we created 2-dimensional ionosphere map using 44 permanent Global Positioning System(GPS) stations operated by Ministry of Land, Transport, and Maritime Affairs. We estimated Vertical Total Electron Content(VTEC) in a fine rectangular grids of $0.1^{\circ}{\times}0.1^{\circ}$ resolution. The observables we used were phase-leveled pseudoranges which are linear combinations of pseudoranges and carrier phases. VTECs were computed for five days during January 25-29, 2003 using the data from 45 permanent stations. In comparison with the Global Ionosphere Map of the Center for Orbit Determination in Europe, RMS differences were at the level of 8 TECU(TEC Unit).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.14 no.1
• /
• pp.27-38
• /
• 1996

Non-scale digital map have important role in the field of GIS and other application area which using geographical data in recently against conventional map restricted by scale and information. The main objective of this study is to develope the automated map production system for small scale map in conjuction with generalization techniques in a digital environment. We will intend to develope algorithms and programs for each generalization operators based on specific terrain feature with vector data. This study will be performed aspects related to an data model development of generalization process, focussing on priority for processing sequency with maintaining vector topology, and error analysis for generalized digital data.