• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.238-267
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• 2023

Studies on Earth's rotation and tide since the 19th century are briefly summarized. The theories of precession, nutation, polar motion, and periodic/secular changes in the rate of rotation are described individually. In addition, a brief review of the Milankovitch theory - the hypothesis of the relationship between the Earth's spin/orbital rotational state and the ice ages - is given. Finally, Earth's tides and their theoretical models are briefly explained. Some detailed technical content is summarized in the appendices.

• Journal of the Korean earth science society
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• v.31 no.2
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• pp.185-204
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• 2010

Inquiring earth science phenomena is characterized by the followings: a big scale of time and space, inaccessibility, uncontrollability, and complexity. Thus, it is very difficult or, in some cases, impossible to investigate them through the actual manipulation in laboratories. Therefore, it is necessary to provide chance for students to experience scientific inquiry without actual manipulation in earth science classes. This study is to explore the role of reasoning based on a thought experiment as a representative model without actual manipulation, and to investigate features of various inquiry models using reasoning in classes. We can make implications when applying for applying each inquiry model to earth science classes, proposing a reasoning-based inquiry model embedded in earth scientific phenomena.

• Journal of the Korean earth science society
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• v.33 no.7
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• pp.672-682
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• 2012

The purpose of this study is to investigate elementary school science gifted students' perceptions about Earth systems and environmental problems. A total of 28 students in the attached center for science gifted education to the university participated in this study. Through the survey, participating students were asked to respond to their self-reported knowledge level, the perceived danger levels, certainty, and tangibility of the selected 13 Earth environmental problems. The DAET (Draw-An-Earth Test)-Checklist were developed and used to analyze the images of the Earth drawn by students. Additional interviews were conducted to clarify the meanings and components of students' image. Results indicated that a total of 80 components regarding Earth systems, 11 components of Earth systems interaction, and 4 components related to Earth systems literacy were identified through the DAET-Checklist and additional interviews. Regarding the students' self-reported knowledge level, they reported that they were most knowledgeable about air pollution, global warming, and water pollution. and they also recognized global warming, air pollution, and water pollution as the most dangerous problem. Results indicated that participants were certain that acid rain, air pollution, and water pollution were problematic, and that acid rain, air pollution, and forest desertification were tangible issues. It is anticipated that this study contributes to understanding the elementary school science gifted students' perceptions toward the selected Earth systems and environmental problems.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1073-1080
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• 2010

In this paper, the centrifuge model tests were conducted for the sake of measuring three dimensional arching earth pressure while two step excavation of the vertical shaft. The results of the centrifuge model tests were compared to newly suggested arching earth pressure equation proposed by Kim et al(2009) and two dimension earth pressure(Rankine). As the results, Measured arching earth pressure revealed about 35 percentages of two dimension earth pressure(Rankine) and almost same as that of newly suggested arching earth pressure equation.

• 한국지구과학회:학술대회논문집
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• 2004.02a
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• pp.58-58
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• 2004

• 한국지구과학회:학술대회논문집
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• 2003.09a
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• pp.69-70
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• 2003

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.467-470
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• 2006

The earth volume which is the basis of all the construction has gone through great development so far with the use of construction machine; however, systematic studies on the related area is in need since the appropriate compound engineering method of earth volume equipments which is a key factor for shortening the project duration and cost reduction is not systematically established and it is dependent on experience. Reasonable mechanical earth volume should take into consideration of performance and characteristics of the equipment, the kind of project, scale and conditions in advance. Also, the optimum compound engineering should be planned by selecting several available scales of equipment. In this study, the earth volume estimate model is established for optimum compound engineering of earth volume equipment for mechanized earth volume equipment loading and moving stage among many stages of earth volume task using system dynamics technique. The optimum compound engineering model of the earth volume equipment produced as a result of this is expected to make reasonable decisions in the shortest time in selecting earth volume facility.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.8
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• pp.1057-1065
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• 2010

Two experiments were conducted to compare the effects of feeding a newly-developed rare earth mineral-yeast product, zinc oxide (ZnO) or antibiotics on the performance, nutrient digestibility and serum parameters of weanling pigs. In experiment 1, 150 crossbred barrows (24 d old and 6.28 kg BW) were fed one of five dietary treatments consisting of an unsupplemented basal diet or the basal diet supplemented with antibiotics (33 ppm tiamulin and 100 ppm chlortetracycline), ZnO (1,500 or 2,500 ppm) or 0.1% peptide-bound rare earth mineral-yeast. In experiment 2, 576 crossbred barrows (28 d old and 7.20 kg BW) were fed the same diets as those used in experiment 1 modified only by the addition of 1.0% Celite 545 to all diets as a digestibility marker. However, the negative control was not included. In experiment 1, weight gain was significantly lower (p<0.05) for pigs fed the negative control than for pigs fed diets supplemented with antibiotics, ZnO, or rare earth mineral-yeast. Pig performance did not differ between pigs fed the four supplemented diets. In experiment 2, there were no differences in performance between pigs fed diets supplemented with antibiotic, ZnO or rare earth mineral-yeast. The digestibility of dry matter, crude protein, calcium, phosphorus and energy were significantly (p<0.01) higher on the rare earth mineral-yeast diet than on diets supplemented with ZnO. In addition, pigs fed the diet supplemented with rare earth mineral-yeast had significantly (p<0.05) higher digestibility of histidine, lysine, threonine and valine than pigs fed the ZnO supplemented diets. Digestibility coefficients for pigs fed antibiotics tended to be intermediate to those of pigs fed rare earth mineralyeast or ZnO. In conclusion, the performance of pigs fed rare earth mineral-yeast was basically equal to that of pigs fed antibiotics or ZnO indicating that rare earth mineral-yeast can be successfully used as a growth promoter in diets fed to nursery pigs. The effects of rare earth mineral-yeast appeared to be mediated through improvements in nutrient digestibility.

• Journal of the Korean earth science society
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• v.30 no.1
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• pp.96-110
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• 2009

The ESE (Earth Systems Education) teaching module was developed to teach an "Earth and Star" unit for the 8th grade (aged 14) students. The planet remodeling activity was developed as a sub-ESE teaching module. The main point of this activity was that students were supposed to remodel planets for life to live on. The purpose of this study was to visualize students' thought and to interpret their understandings through their drawings and writings. A framework of analysis with four categories was designed and applied to analyze students' cognitive structure. In order to explore students' cognitive contents, the analyzing factors were classified into two domains: subsystems of the earth systems and use of science & technology. Results revealed via the planet remodeling activity that students' cognitive characteristics were impacted by ESE activities such as Earth literacy.

• Journal of the Korean earth science society
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• v.29 no.2
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• pp.175-188
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• 2008

The purposes of this study were to develop an Earth systems-based earth science module and to investigate the effects of field application. The module was applied to two classrooms of a total of 76 second-year high schoolers, in order to investigate the effectiveness of the developed module. Data was collected from observations in earth science classrooms, interviews, and questionnaires. The findings were as follows. First, the Earth systems-based earth science module was designed to be associated with the aims of the national Earth Science Curriculum and to improve students' Earth science literacy. The module was composed of two sections for a total of seven instructional hours for high schoolers. The former sections included the understanding of the Earth system through the understanding of each individual component of the system, its characteristics, properties and structure. The latter section of the module, consisting of 4 instructional hours, dealt with earth environmental problems, the understanding of subsystems changing through natural processes and cycles, and human interactions and their effects upon Earth systems. Second, the module was helpful in learning about the importance of understanding the interactions between water, rock, air, and life when it comes to understanding the Earth system, its components, characteristics, and properties. The Earth systems-based earth science module is a valuable and helpful instructional material which can enhance students' understanding of Earth systems and earth science literacy.