• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.22-28
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• 2005

The electrical characterstic of earth is the most dominant factor for grounding design and an earth is typically represented by a uniform medium with the specific earth resistivity, which is unique for a specific site. For a hand-working grounding design using a specific earth resistivity requires a process converting a real earth of complex medium into a simple uniform medium In this paper, we suggest a procedure to convert a multi-layered earth s into a simpler uniform earth for grounding design of Myanmar 500[kV] transmission towers.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.1
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• pp.88-94
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• 2012

This study was created to resolve the problems embedded in the formal measuring experiments to determine the earth's size in the current curriculum, to develop an updated measuring experiment to determine the earth's size and to establish its effect. For this study, pre-service elementary teachers, who had attempted the experiment of measuring the size of the earth when they were in middle school, performed the experiments in the existing national curriculum, and their responses, collected through in-depth interviews, were examined. To begin with, the pre-service elementary teachers conducted the experiment of measuring the earth size and they recorded the problems while performing it. At the end, an in-depth interview was administered. Based on the problems, an updated measuring experiment to determine the earth's size was suggested to be applied to the same contents and be analyzed through the in-depth interviews. Common themes which were mutually categorized and analyzed by the two researchers were obtained based on the records produced while conducting the experiment and the in-depth interview data. The teachers mentioned that the experiments for measuring the size of the earth in the current curriculum gave rise to difficulties in measuring precisely the angles between the string and the post. Also, there has been a scientific contradiction that solar altitudes were increased in a high latitude region, instead of decreased. For this reason, an alternative method has been developed to measure the earth's size using the distance and the solar altitude difference of two places. The teachers all agreed that by using the updated measuring experiment, they can acquire more precise measurements and it is easier, faster and consequently more effective than the existing methods. Through the results of this study, I suggest that the newly developed experiment by the researchers can overhaul the problems of the current experiments and it can be an effective alternative to the current experiment.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.169-174
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• 2003

Design of a rational earth volume conversion coefficient is required as the earth volume conversion coefficient may give great influence on construction work volume and construction costs in the civil engineering works where large-scaled earth volume is excavated. However, there are a great deal of difficulties in the calculation of the exact spoil surface earth and Insufficient earth volume by adopting the figures presented on the generally used design specifications which are not the results obtained from the selection tests in calculating the earth volume conversion coefficient. In this connection, it would be desirable to calculate the earth volume conversion coefficient by carrying out large-scaled site test adequate for the relevant environment. In consequence, this study aims at calculating the exact earth volume conversion coefficient of cutting and banking areas of weathering rocks in large-scaled construction sites where land is being developed into home lots. For this, we have excavated the respective 20 sites of the cutting and banking areas in the said site and then calculated the volume after the excavation. As a result, the relative exactness degree of the crossing was calculated at 0.5% in average. The relative exactness degree of 0.5% in the volume may be judged as an exact measurement as it corresponds to 0.17% of the relative exactness degree in the length measurement. We have calculated the exact earth volume conversion coefficient by the use of function ratio as per the wet unit weight and the indoor soil quality test as per volume calculated. And then we have found out minor differences as a result of the comparison and analysis with the earth volume conversion coefficient determined by the dry unit weight test as per sand replacement method. This may be judged as a rational design method for the calculation of earth volume conversion coefficient, as well as high reliability of site test as a precision photogrammetry is adopted for volume measurement of the irregular excavating areas.

• Journal of the Daesoon Academy of Sciences
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• v.25_2
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• pp.45-70
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• 2015

Master Jeungsan understood a general view of Pungsu but actually he used the theory of Pungsu in his own religious perspective, transcending it. The theory of Pungsu is different. But the fact that it is premised on the principle of 'in and yang', the five-element principle, the Book of Changes, energy thought, and To chugi piyung, etc. is generally recognized. The three important elements of Pungsu are mountain, water, and direction or man. Pungsu has formal principles such as Gallyongbeop, Jangpungbeop, Deuksubeop, Jeonghyeolbeop, Jwahyangbeop, and Hyeongukron. etc. In the late of Joseon, Jeungsan established a new traditional thought, understanding Bibopungsu, Gukdopungsu, Minganpungsu, etc. However, he reinterpreted them to be suitable to his religious ideal and let his followers understand them as well. In particular, Jeungsan overcame the previous view on earth and expressed a new perspective to enhance earth up to the level of heaven. In the perspective of the traditional world, earth is lower than heaven, but Jeungsan made it a status equal to heaven. He mentioned that in the past, the culture and history of man was influenced by earth's energy but today, at the age of man respect, he put passive man influenced by earth-condition on the more subjective and active status. Even though he mentioned different Pungsu, Hyeongguk, and Hyeolmyeong, he expressed the shape of Pungsu within the construction of three worlds, the one of heaven and earth transcending good or ill luck or a favorable change in fortune. He practised the expedient of Pungsu from the stand of the construction of heaven and earth instead of the usage of Bibopungsu, Gukdopungsu, and Minganpungsu. He diagnosed that the division of the world is caused by the one of earth and tried to solve it. Moreover, he said that Myeongdang(a propitious site) must be the man-orientation rather than the earth-orientation. It means that Pungsu, stressing the energy of earth and turning one's luck, is changing into the world of man-orientation. In other words, Jeungsan diagnosed the world of Pungsu but he ultimately used Pungsu theory in building up his own view of religious world transcending such a theory.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.2
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• pp.214-225
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• 2017

The first accurate estimate of the Earth's circumference was made by the Hellenism scientist Eratosthenes (276-195 B.C.) in about 240 B.C. The simplicity and elegance of Eratosthenes' measurement of the circumference of the Earth by mathematics abstraction strategies were an excellent example of ancient Greek ingenuity. Eratosthenes's success was a triumph of logic and the scientific method, the method required that he assume that Sun was so far away that its light reached Earth along parallel lines. That assumption, however, should be supported by another set of measurements made by the ancient Hellenism, Aristarchus, namely, a rough measurement of the relative diameters and distances of the Sun and Moon. Eratosthenes formulated the simple proportional formula, by mathematic abstraction strategies based on perfect sphere and a simple mathematical rule as well as in the geometry in this world. The Earth must be a sphere by a logical and empirical argument of Aristotle, based on the Greek word symmetry including harmony and beauty of form. We discuss the justification of these three bold assumptions for mathematical abstraction of Eratosthenes's experiment for calculating the circumference of the Earth, and justifying all three assumptions from historical perspective for mathematics and science education. Also it is important that the simplicity about the measurement of the earth's circumstance at the history of science.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1796-1801
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• 2007

This paper presents electric potential rise on the surface of the earth due to ground currents. It is the aim of this paper to propose fundamental data relevant to the earth surface potentials depending on the soil structures. The earth potential rise, touch and step voltages in the immediate vicinity of the ground rod of a distribution pole were measured and analyzed. The results described in this paper are based on laboratory measurements which were intended to simulate conditions existing in actual installations. As a result, the earth surface potential rise, touch and step voltages strongly depend on the soil structure. The highest earth surface potential occurred in the vicinity of the top of ground rod. When the ground rod was installed in the distance range of $1{\sim}1.5\;m$ from distribution pole, the highest touch voltages appeared near the place of 1 m on the straight line connecting the distribution pole to ground rod.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.159-166
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• 1999

As the spatial resolution of remote sensing satellites becomes higher, very accurate determination of the position of a LEO (Low Earth Orbit) satellite is demanding more than ever. Non-symmetric Earth gravity is the major perturbation force to LEO satellites. Since the orbit propagation is performed in the celestial frame while Earth gravity is defined in the terrestrial frame, it is required to convert the coordinates of the satellite from one to the other accurately. Unless the coordinate conversion between the two frames is performed accurately the orbit propagation calculates incorrect Earth gravitational force at a specific time instant, and hence, causes errors in orbit prediction. The coordinate conversion between the two frames involves precession, nutation, Earth rotation and polar motion. Among these factors, unpredictability and uncertainty of Earth rotation, called UTI-UTC, is the largest error source. In this paper, the effect of UTI-UTC on the accuracy of the LEO propagation is introduced, tested and analzed. Considering the maximum unpredictability of UTI-UTC, 0.9 seconds, the meaningful order of non-spherical Earth harmonic functions is derived.

• Journal of the Korean earth science society
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• v.38 no.5
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• pp.357-366
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• 2017

Urban planning and engineering undergraduate students need to understand the earth physical systems and that how human beings interact with the earth systems to planning and engineering urban area. The eco-friendly or geo-friendly design and planning of an urban area is a critical issue not only for economic benefits but more importantly for the sustainable future of urban life. However, little study has been done dealing with the urban engineering students' understanding of the earth as a system and what pedagogical approach is appropriate to improve their understanding of the earth as a system. This study is to investigate the impact of a purposely designed ESS course on urban engineering students' understanding of the earth as a system and their perceptions about the instructional approaches of the course on their learning competency. This study utilized a mixed-methodology with three main data sources: concept maps, student's perception survey about their learning competency, and course contents. Both the survey and concept maps were analyzed quantitatively as well as qualitatively. The result of this study showed that the urban engineering students' experience of team-based research about the topic they chose based on their own interest had a positive impact on their understanding of the earth as a system and their learning competency. The results of this study suggest that structuring and presenting the earth system contents in the context of engineering students' understanding and their future career be effective not only for the improvement of students' content knowledge but also for the enhancement of their learning competency such as creativity and problem-solving skills in everyday life situation.

• Journal of the Korean Society of Earth Science Education
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• v.13 no.3
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• pp.297-304
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• 2020

This study is to find out experiments of Earth's revolution and which experiment is effective by school level. Researcher investigated and developed eight experiments for students to learn Earth's revolution. Twenty six pre-service teachers did these experiments, discuss about them, chose an effective experiment of Earth's revolution and wrote the reason why. As a result, they thought that an experiment of seasonal constellations is effective for elementary school students, an experiment of seasonal star's spectrum is effective for secondary school students and an experiment of the superior planets' retrograde motion is effective for university students. Pre-service teachers gave reasons such as hands-on experience, connection with textbooks, background knowledge and higher-level thinking.

• Journal of the Korean earth science society
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• v.26 no.4
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• pp.336-346
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• 2005

This study identifies and compares science content standards that are approved by departments of education in six states: California, Connecticut, Michigan, New Jersey, Texas, and Virginia. Specifically, the study examines the goals/visions, the organizing/progression principles, the strands of science content, and earth science content found in the states curriculum standards compared to National Science Education Standards. Although many states followed the recommendations of NSES or Project 2061, the format and content of the state science standards reviewed are very diverse. The diversity seems to reflect the diverse perspectives and needs of the states. The results of this study provide Korean educators and teachers with useful models or examples to incorporate Korean national science curriculum guides into the science curriculum frameworks of their regions or schools.