• Journal of the Korean earth science society
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• v.31 no.3
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• pp.267-275
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• 2010

The purpose of this study is to investigate student's Acquisition about the conception of the Earth Rotation between difference of their Spatial Sensibility. In this study, four students were selected out of 83 9th graders in Gwangju, Korea. The spatial sensibility test instrument was developed by the Korean Testing Center, and the test instruments of 'the movement of celestial bodies' were developed by Kim (1997). The results were as follows: Students with higher spatial sensibility understood precisely about the Earth's rotation in stereoscopic space. However, those with lower spatial sensibility failed to grasp the Earth's rotation and memorized it as fragmentary concepts. As for gender effect, male student with higher spatial sensibility explained the concepts clearly, while that with lower spatial sensibility has difficulty with the Earth's rotation in relation to the diurnal motion of celestial bodies. On the other hand, female student with higher spatial sensibility explained the concepts correctly in detail, while that with lower spatial sensibility had difficulty explaining the concepts in stereoscopic space. Therefore, students with higher spatial sensibility should be presented with problems in which they form their own solution. Those with lower spatial sensibility should be allowed to understand the phenomena intuitively. In developing teaching methods, female students should interact with the concepts in stereoscopic space directly, while male students should consider the celestial objects from various viewpoints. Then spatial sensibility in relation to the movement of celestial bodies would be expected to improve.

• Journal of The Korean Association For Science Education
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• v.34 no.8
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• pp.703-718
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• 2014

This study sought to investigate learning progressions for astronomical systems which synthesized the motion and structure of Earth, Earth-Moon system, solar system, and the universe. For this purpose we developed ordered multiple-choice items, applied them to elementary and middle school students, and provided validity evidence based on the consequence of assessment for interpretation of learning progressions. The study was conducted according to construct modeling approach. The results showed that the OMCs were appropriate for investigating learning progressions on astronomical systems, i.e., based on item fit analysis, students' responses to items were consistent with the measurement of Rasch model. Wright map analysis also represented that the assessment items were very effective in examining students' hypothetical pathways of development of understanding astronomical systems. At the lower anchor of the learning progression, while students perceived the change of location and direction of celestial bodies with only two-dimensional earth-based view, they failed to connect the locations of celestial bodies with Earth-Moon system model, and they could recognized simple patterns of planets in the solar system and milky way. At the intermediate levels, students interpreted celestial motion using the model of Earth rotation and revolution, Earth-Moon system, and solar system with space-based view, and they could also relate the elements of astronomical structures with the models. At the upper anchor, students showed the perspective change between space-based view and earth-based view, and applied it to celestial motion of astronomical systems, and they understood the correlation among sub-elements of astronomical systems and applied it to the system model.

• Journal of The Korean Astronomical Society
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• v.35 no.2
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• pp.75-85
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• 2002

We present N-body simulations of globular clusters including gravitational field of the Galaxy, in order to study effects of tidal field systematically on the shape of outer parts of globular clusters using NBODY6. The Galaxy is assumed to be composed of central bulge and outer halo. We mvestigate the cluster of multi-mass models with a power-law initial mass function (IMF) starting with different initial masses, initial number of particles, different slopes of the IMF and different orbits of the cluster. We have examined the general evolution of the clusters, the shape of outer parts of the clusters, density profiles and the direction of tidal tails. The density profiles appear to become somewhat shallower just outside the tidal boundary consistent with some observed data. The position angle of the tidal tall depends on the location in the Galaxy as well as the direction of the motion of. clusters. We found that the clusters become more elongated at the apogalacticon than at the pengalacticon. The tidal tails may be used to trace the orbital paths of globular clusters.

• 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.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1048-1049
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• 2015

The sihwa tidal power plant is the first tidal power plant in korea and the biggest of the world. The tidal power turbine is operated by tidal energy. The tidal energy is generated by the relative motion of the earth and celestial masses specially the sun and the moon, which interact via gravitational forces. The tidal power is estimated by the predicted the tidal amplitude and phase. This paper gives a process of estimate of tidal power using Matlab T-tide based on tide prediction. The proposed method is tested using actual recorded data comparing to predicted date.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.673-689
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• 2022

To understand seasonal changes it is necessary to understand the relationship between celestial bodies in a three-dimensional space, and to this end, modeling activities in which students directly construct, use, evaluate, and modify three-dimensional models are important. In this study, the process of elementary school students using globes and light bulbs to model Earth's motion in a three-dimensional space as a cause of seasonal changes was analyzed. Seventeen sixth graders participated in the modeling process. After exploring phenomena and concepts related to seasonal change, students constructed models using globes and bulbs and used them to explain seasonal changes. Video data recording students' modeling process, students' activity sheets, and transcripts of post-interview were used as research data, and data triangulation was conducted. The modeling level analysis framework was also developed based on previous studies. In particular, the framework was developed in detail in this study in consideration of the concept of Earth's motion as well as understanding model and implementing modeling. In the final analysis framework, the 3D modeling level was classified from level 1 to level 3, and student performance that may appear at each level was specified. As a result of the study, there were two main levels of modeling using globes for elementary school students to explain seasonal changes. The rotation and tilt of the axis of rotation and revolution of the earth were considered but the level at which empirical evidence was not used (level 2), the level at which empirical evidence was used to explain seasonal chages (level 3). However, even when students use empirical evidence, it did not lead to the construction of a scientific model. In this study, the cause was explored in relation to the characteristics of the tool used for modeling.

• Journal of the Korean earth science society
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• v.42 no.3
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• pp.325-343
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• 2021

This study aims to develop two science education programs using Angbuilgu and ancient astronomical data, are Korean astronomical heritage, and explore its educational possibility through the pilot application. Considering the TSK compositional characteristics of Angbuilgu and ancient astronomical data, linkage with science curriculum, and linkage with NOS, Angbuilgu was developed as a hands-on activity for elementary school students and ancient astronomical data as a science inquiry activity for middle and high school students. The educational availability of the developed program was confirmed by pilot application to elementary and high school groups. Through the Angbuilgu activity, the students refined their conceptual knowledge by correcting misconceptions about the solar motion by season and then confirmed the possibility of connection with the concept of the celestial coordinate system. Students recognized the scientific value of Angbuilgu and understood the nature of interactions STS. In the ancient astronomical data activity, students experienced inductive and deductive inquiry methods and utilized various information and strategies. Through the activities, students improved their scientific understanding and attitude towards TSK.

• Publications of The Korean Astronomical Society
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• v.36 no.3
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• pp.79-95
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• 2021

This study aims to develop a restoration model of an armillary sphere of Tongcheon-ui (Pan-celestial Armillary Sphere) by referring to the records of Damheonseo (Hong Dae-Yong Anthology) and the artifact of an armillary sphere in the Korean Christian Museum of Soongsil University. Between 1760 and 1762, Hong, Dae-Yong (1731-1783) built Tongcheon-ui, with Na, Kyung-Jeok (1690-1762) designing the basic structure and Ann, Cheo-In (1710-1787) completing the assembly. The model in this study is a spherical body with a diameter of 510 mm. Tongcheon-ui operates the armillary sphere by transmitting the rotational power from the lantern clock. The armillary sphere is constructed in the fashion of a two-layer sphere: the outer one is Yukhab-ui that is fixed; and the inner one, Samsin-ui, is rotated around the polar axis. In the equatorial ring possessed by Samsin-ui, an ecliptic ring and a lunar-path ring are successively fixed and are tilted by 23.5° and 28.5° over the equatorial ring, respectively. A solar miniature attached to a 365-toothed inner gear on the ecliptic ring reproduces the annual motion of the Sun. A lunar miniature installed on a 114-toothed inner gear of the lunar-path ring can also replay the moon's orbital motion and phase change. By the set of 'a ratchet gear, a shaft and a spur gear' installed in the solstice-colure double-ring, the inner gears in the ecliptic ring and lunar-path ring can be rotated in the opposite direction to the rotation of Samsin-ui and then the solar and lunar miniatures can simulate their revolution over the period of a year and a month, respectively. In order to indicate the change of the moon phases, 27 pins were arranged in a uniform circle around the lunar-path ring, and the 29-toothed wheel is fixed under the solar miniature. At the center of the armillary sphere, an earth plate representing a world map is fixed horizontally. Tongcheon-ui is the armillary sphere clock developed by Confucian scholars in the late Joseon Dynasty, and the technical level at which astronomical clocks could be produced at the time is of a high standard.

• Journal of the Korean earth science society
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• v.32 no.7
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• pp.902-912
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• 2011

The purpose of this study was to investigate the effects of teaching based on analysis of a hierarchy of the concepts associated with astronomical observation as well as each learner's status of knowledge through analytical methods of the knowledge state. A test instrument was developed to measure high school students' concepts associated with astronomical observation before instruction. The learners' psychological hierarchy associated with astronomical observation that the participants possessed showed the order of 'motion of the earth${\rightarrow}$coordinate system${\rightarrow}$astronomical observation (mechanism of the telescope${\rightarrow}$installation of the telescope${\rightarrow}$observation through the telescope)', and so was the hierarchy of teaching (70.6%). The learners' knowledge state that is supposed to be similar each other in the ability of observing celestial bodies was different even through they scored the same on the concept test. There were cases with the knowledge state well-structured and not well-structured, which suggests that differentiated instruction with appropriate teaching-learning prescriptions be prepared. An analysis of the knowledge state can play the role of both preparing individualized learning prescriptions and formative evaluation. In the unit dealing with astronomical observation of Earth ScienceI, teaching according to the psychological hierarchy of learners rather than the order in which the textbook syllabi were presented scored significantly higher (p<0.05) on the level of concept achievements. This result suggests that the teacher can help students achieve more efficient in learning by analyzing the learner's knowledge state and reordering the syllabi of the textbook in teaching the concepts associated with astronomical observation.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.489-500
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• 2005

The objective of this study is to examine the cognitive process that undergoes a middle student’s conceptual change about the universe by the cognitive conflict, using science history materials as a teaching strategy. Four eighth graders were selected and classified by three cognitive level. Students were interviewed and conducted to an inquiry activities regarding their viewpoint about the universe after each class, and their conceptual change patterns were analysed from pre-test and post-test. This study showed that each student held dissimilar astronomical preconceptions and various misconceptions about celestial motion. Students at the formal operational stage and transitional stage experienced the conceptual change from geocentricism to heliocentricism by instructional model upon the science history materials. Student at the concrete operational stage had either unscientific conception, no conception, or could not have a conceptual change even when being presented with an environment that arouses cognitive conflict ($R^2$: Phase change of Venus and its Rise and set time). They ended up having a cognitive change from geocentricism to heliocentricism by solving another problem ($R^2$: Relation between visible diameter and position of Mars). After the instruction, a conceptual achievement progress was reported with a $10\%$ improvement. Therefore, the instruction model based upon science history was effective on student’s scientific conceptual change.