• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.5-15
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• 2023

The evaluation of passive earth pressure plays a crucial role in the design of earth-retaining structures such as retaining walls and temporary earth-retaining walls to withstand horizontal earth pressure. In the earth pressure theory, active and passive earth pressures represent the earth pressures at the limit state, where the wall displacement reaches the maximum allowed displacement. In the design of earth-retaining structures, the passive earth pressure is considered as the resisting force. In this context, the limit displacement at which passive earth pressure occurs is significantly greater than that associated with the active earth pressure. Therefore, it is irrational to apply this displacement directly to the calculation of passive earth pressure. Instead, it is necessary to consider the mobilized passive earth pressure exerted at the allowable horizontal displacement to evaluate the structural stability. This study proposes an allowable wall displacement, denoted as 0.002 H (where H represents the excavation depth), based on a literature review that focuses on sandy soils. To calculate the mobilized passive earth pressure from the wall displacement, a semi-empirical equation is proposed. By analyzing the obtained data on mobilized passive earth pressure, a reduction factor applicable to Rankine's passive earth pressure is proposed for practical application in sandy soils under different wall movement types.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.129-138
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• 1994

It is well recognized that accurate analysis of lateral earth pressure is very signficant factor which determines the design amount of braced cut walls and braced systems. Many researchers, Peck, Terzaghi-Peck and so on, make a study about lateral earth pressure to act on the flexible walls. But these studies trouble accurate to multy layered systems like inland areas in Korea. This study is compared with the field messurement data to estimate the earth pressure distributions in multy layered areas and the empirical earth pressure distributions. The conclusions are as follows : At final excavation depth, the lateral earth pressure which messured by field instrument is smaller than the empirical earth pressure. (About 1.85~5.32 times). In the case of considering the soft rock layer to the final excavation depth, the messured earth pressure is safe to be compared with empirical earth pressure. The messured earth pressure distributions are like that the upper soil layer is small the middle soil layer is large, the rock mass layer is very small.

• Journal of the Korean earth science society
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• v.23 no.2
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• pp.188-193
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• 2002

Various research methods have been used in science depending on the various contexts. This implies that certain methods or inferences may be more frequently used in earth science. The purpose of the study are to explore the contexts of earth science, and the inferences frequently used in earth science. The context earth science research is quite different from that of other areas of natural science in terms of its time scale, space scale, accessibility, complexity, and controllability. The purpose of earth science research is twofold: historical and causal. The inferences frequently used in earth science are abduction and prediction. Abductive inferences go from the resulting state to controlling state. Predictive inferences go from hypothesis to expected data.

• Journal of Korean Elementary Science Education
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• v.30 no.2
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• pp.204-212
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• 2011

This research is about the six graders' preconceptions in elementary school about a cause of the seasonal change before learning. The result of this research is that the patterns of six graders's preconceptions in elementary school are earth's rotation, earth's revolution, the distance between the earth and the sun and the location factor between the sun and our country, which are mixed up with two more things. Especially many patterns of students explain the seasonal change of our country using the change of location of our country by earth's rotation, the location factor between the earth and the sun and the distance between the earth and the sun by earth's revolution.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1073-1074
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• 2006

In this paper, we perform a simulation to verify the earth resistance values in Common Earth Network. The simulation is performed on the assumption that certain shorts are occurred in common earth network. Furthermore, from the result, we confirmed that very small earth resistance values in common earth network are given, by carrying out practical measurements in railway sections where common earth network is composed. From the effect, we could discover that the construction of common earth network is in a disadvantageous position on the financial aspect, while it is the most desirable way of construction for the purpose of Earth.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.269-274
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• 2005

This paper is studied on earth network configuration when common earth is applied to electrified railway system. And the permitted capacity of buried earth cable used for configuring common earth network and application plan of existing individual earth system when common em1:h network is applied to existing electrification line improvement are studied. For this, the configuration of common earth network is examined according to the SNCF regulation, and the interface between common earth and individual earth is analysed on the basis of the existing track circuit used in electrified line.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.653-660
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• 1999

Any mechanical system has a natural oscillation which can be excited, and the earth is no exception. The earth can oscillate in an indefinite number of normal modes of oscillation, rather like a giant bell. The various free modes are generally sparated into two categoridal modes and toroidal modes. Clearly the toroidal modes will produce no perturvation of the gravity field and no vertical acceleration on the surface of the earth. Hence only spheroidal modes can be detected with a gravimeter. EarthTide gravimeter was installed at AIMST in order to observe free modes of the earth. Eight major earthquakes including chinese earthquake (magnitude 7.3) with free oscillations of the earth are observed during one year (1998. 8. 1∼1999.7.31). And then the earth tides components were eilminated from earthquake records using a numerical Butterworth highpass filter. Spectral analysis of gravity readings repersent that 48 observations of shheroidal modes. The relationships between instrumental observations and theoretical predictions based on the Gutenberg earth model agree well those resulting from free oscillation in Korea.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.497-500
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• 2005

Research and development of remote sensing technique is necessary so that more accurate and extensive information may be obtained. To achieve this goal, the synthesized technique which integrates the high resolution optic and SAR image, and topographical information was examined to investigate the quantitative/qualitative characteristics of the Earth's surface environment. For this purpose, high-precision DEMs of Jeju-Island was generated and data fusion algorithm was developed in order to integrate the multi-spectral optic and polarimetric SAR image. Three dimensional land-cover and two dimensional soil moisture maps were generated conclusively so as to investigate the Earth's surface environments and extract the geophysical parameters.

• Journal of the Korean earth science society
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• v.27 no.7
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• pp.730-744
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• 2006

The United States curriculum reform movement has recently started in each area of science education. The initiatives on curriculum reform stem from a notion that the low rate of science curricula offered in schools has been a serious problem. The schools in the United States are not only facing a lack of offerings within science curricula but also low enrollment in science courses, especially in physics, chemistry, and earth science. This trend resulted in low performances on international achievement tests including TIMSS and PISA. This paper introduces the efforts to solve existing problems through curriculum reform; including ChemCom, BioCom, EarthComm, and Active Physics. In this paper, a discussion is presented to show how the curricula can help address the status quo in science education. More specifically, this paper focuses on curriculum reform in high school earth science (EarthComm), providing a closer look at the scope and sequence of the reform movement. EarthComm was chosen because it was released based on the development of the National Science Education Standards (NRC, 1996). Consequently, EarthComm became a curriculum that espoused the visions of the Standards, which has been guiding the reform of the US curriculum. At the end of this paper, two research outcomes of the EarthComm curriculum implementation in schools are discussed in terms of student learning and differences from conventional curricula.

• Journal of the Korean Society of Earth Science Education
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• v.7 no.2
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• pp.159-168
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• 2014

This study was designed to 10 questions as development of GAP program for ninety high school students(each student of 30 with achievement as high, medium, and low categories), it was analyzed the perception of Earth scientist. High school students have a positive perception about a course in Earth science, but they have lack of knowledge about Earth scientist as a career man, and they can't recognize Earth scientist as a career. A failure of learning of Earth science for Students with low level achievement leads to a negative perception about Earth scientist and disconnection to future career. School education should provide an opportunity to encounter Earth scientist for students and it is badly in need of effort to connect to the job training program.