• Geotechnical Engineering
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• v.4 no.1
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• pp.7-16
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• 1988

The safety factor has been used widely and uniquely at present to check the safety of the structure . However, probability of failure would be logically attempted to check the reliability of the structure in future Coulomb's theory or Rankine's theory has been applied in practice to retaining earth structure in spite of the fact that the lateral earth pressure, which is the primary factor in the determination of wall structure, depends on the modes of wall movement . This study is concentrated on the two modes of , wall movement (active case rotation about bottom(AB) , active case rotation about top(AT)) of the overturning'failure of vertical wall with horizontal sand backfill . The static active earth pressure is determined by applying each of Coulomb's theory, Dubrova's redistribution theory and Chang's method The earthquake active earth pressure is determined by adding Seed and Whitman's earthquake pressure to the static earth pressure , On the condition that design variables are fixed with each of the above earth pressure, reliability is analyzed using the recently developed method of AFOSM (Advanced First Order Second Moment)

• Journal of the Korean earth science society
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• v.37 no.5
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• pp.309-322
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• 2016

This paper presents an analytical framework of Conceptual Understandings of Earth Systems (CUES) that shows a relationship between disciplinary knowledge of Earth systems and the specific thinking skills required to understand that knowledge. This framework is developed through an extensive literature review of students' and teachers' understandings of earth systems concepts and systems thinking in earth science context. This study first presents the categories of disciplinary knowledge of Earth systems, Earth System Knowledge (ESK). This study then illustrates a relationship between categories of ESK and the ontological categories (Matter, Process, Systems) that has been used to study students' conceptual understandings of Earth systems. Finally, this study presents the CUES framework to show the relationship between disciplinary knowledge and thinking skills. The implications of using this framework for curriculum development, assessment, and teacher education and ESS research are discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.10a
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• pp.29-32
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• 1993

Presengly reinforced earth is widely utilized for earth structure increasingly not only domestic but also in many foreign countries because of its rapidity of construction and economic merits. The study on the reinforced earth has been actively carried out and enlarged in the theoretical aspect. But it has many problems to the application of the field. In this study large scale Pull-out Test was used to analyze reinforced earthe behavior considering deformation character of reinforced earth under the similar condition to the field.

• Journal of The Korean Association For Science Education
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• v.27 no.5
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• pp.367-378
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• 2007

The purpose of this study is to investigate the features of science language in Earth science textbooks and Earth science research articles. We examined two Earth science textbooks and two Earth science articles using the taxonomy of scientific words, the text structure analysis of explanations, the analysis of conjunctive relations and reasoning, and the function of conjunction. The results showed that school science language revealed in Earth science textbooks had high proportion of naming words and the text structures in which definition/exemplification structure and description structure were dominant. Also, internal relations that showed additional arrangement rather than logical inference, were predominant in Earth science textbooks. However, scientists' science language revealed in the Earth science articles had more proportion of process words and concept words than the Earth science textbooks and the schematic structure of explanation texts, such as orientation - implication sequence - conclusion. In addition, the text structures in each sentences of implication -sequence showed cause/effect or problem-solving after description structures. Also each sentences expressed causal or abductive reasoning through the internal relations using verbs or adverbial inflection. It is necessary that we bridge the gap between the two languages for students' authentic use of science language. For the bridging, we propose "interlanguage", which mediates between school science language and scientists' language.

• Journal of the Korean Society of Earth Science Education
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• v.7 no.1
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• pp.11-23
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• 2014

The purpose of this study is to analyze the degree of argumentation structure development and factors of development of preservice teachers through SSI related argumentative writings. The study was conducted with 16 preservice teachers that students taking elementary science education theory class in K university located in Chungbuk. The testees wrote six SSI related argumentative writings (once a week), and we examined the degree of argumentation structure development and the change in the recognition of SSI of the preservice teachers by comparing the writings before and after the experiments. The experimental results showed that argumentation structure of the preservice teachers'writings improved and argument level (argument capability) of them also increased as the number of writing was increased. Factors that affect the argumentation structure improvement are mainly argumentation structure education, a number of writings, feedbacks, and subjects related to SSI. In this aspect, the argumentative writing on SSI has the effect of developing scientific sophistication and enhancing the decision-making power of students, and it has positive impacts in science education.

• Journal of the Korean earth science society
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• v.30 no.7
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• pp.897-908
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• 2009

Inscriptions are integral parts of the current science textbooks, and become medium that makes sense of scientific concepts effectively. This study analyzed the inscriptions from five science textbooks at the secondary level in terms of its type, function, and structures. Analyzing types of inscriptions resulted that the ratio of frequently used photographs and illustrations were much higher than that of graphs and tables used. In case of function analysis, illustrative and complementary functions were dominant in terms of frequency and ratio, whereas explanatory, decorative and inquisitive functions were relatively rare. Inscriptions of single structure was much more than multiple structure. Multiple structure of pair and series were mainly used for representing contrast and sequence, respectively. The proportion of inscriptions in type, function and structure across the textbooks was significantly different. Based on the results, it was suggested that semiotic study about the function and the structure of inscriptions need to be carried out in earth science area to better understand the pedagogical implications of inscriptions in school science.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.5
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• pp.513-522
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• 2015

This study is to confirm the effect of pre-installed pipe-roof by measuring earth pressure acting on the underpass. In recently developed trenchless methods pre-inserted steel pipes before ground excavation to form pipe-roof are connected each other with re-bars and filled with mortar. In this study, focusing on the Upgraded Pipe Roof Structure method (UPRS) and Front-Jacking, earth pressure around pipe-roof is measured after insertion of steel pipe to ensure the effect of earth pressure reduction. In case of the UPRS earth pressure is considerably reduced because of the reinforced effect of pipe-roof. In case of the Front-Jacking in which the whole underpass structure is pushed into the ground, earth pressure is not reduced as expected, because the pre-installed pipes are not needed to be reinforced.

• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.191-201
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• 1999

The interpretation of resistivity data has, so far, mainly been made under the assumption that the earth is of relatively simple structure and then using one or two-dimensional inversion scheme. Since real earth structure and topography are fully three-dimensional and very complicated In nature, however, such assumptions often lead to misinterpretation of the earth structures. In such situations, three-dimensional inversion is probably the only way to get correct image of the earth. In this study, we have developed a three-dimensional inversion code using the finite element solution for the forward problem. The forward modeling algorithm simulates the real field situation with irregular topography. The inverse problem is solved iteratively using the least-squares method with smoothness constraint. Our inversion scheme employs ACB (Active Constraint Balancing) to enhance the resolving power of the inversion. Including Irregular surface topography in the inversion, we can accurately define the earth structures without artifact in the numerical tests. We could get reasonable image of earth structure by Inverting the real field data sets taken over highway bridge construction site.

• The Bulletin of The Korean Astronomical Society
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• v.26 no.1
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• pp.36.1-36.1
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• 2001

• Geomechanics and Engineering
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• v.23 no.3
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• pp.207-215
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• 2020

This paper presents a kinematic limit analysis for passive earth pressure of rigid retaining structures considering the unsaturation of the backfill. Particular emphasis in the current work is focused on the effects of the spatial change in the degree of saturation on the passive earth pressure under different steady-infiltration/evaporation conditions. The incorporation of change of effective unit weight with degree of saturation is the main contribution of this study. The problem is formulated based on the log-spiral failure model rather than the linear wedge failure model, in which both the spatial variations of suction and soil effective unit weight are taken into account. Parametric studies, which cover a wide range of flow conditions, soil types and properties, wall batter, back slope angle as well as the interface friction angle, are performed to investigate the effects of these factors on the passive pressure and the corresponding shape of potential failure surfaces in the backfill. The results reveal that the flow conditions have significant effects on the suction and unit weight of the clayey backfill, and hence greatly impact the passive earth pressure of retaining structures. It is expected that present study could provide an insight into evaluation of the passive earth pressure of retaining structures with unsaturated backfills.