• Journal of the Korean Society of Earth Science Education
• /
• v.8 no.3
• /
• pp.332-345
• /
• 2015

Earth science is the study to explore the planet in which we live. Among these earth science geology of the area it can be the most critical and important study. However, because of the size and scope is too broad temporal spatial eurona covered in geology is true that many students find difficult about the geology field. In this study, in conjunction with landscape formation of geologic time for the concept to be among the core areas of Geology examined the concept and recognize it as the destination for high school students. Is a test tool for the analysis was adapted for use by Jolley (2010) has developed LIFT (The Landscape Identification and Formation Test). Currently we fix the strip to match the country through a validity check of the curriculum. Results of the study were as follows: First, the ability to check the landscape and formation is expected to estimate the time and the liberal arts students was higher than the natural science students. The reason for this seems to be the influence of learning geographical subjects. Second, the concept of geological time was found to lack both natural science and liberal arts students. The reason is that the students in the previous process because it deals with the concept of geologic time from the top of Earth Science Education II seems to be because there was no chance of learning about geological time. Third, the results confirm the confidence of the students surveyed in the landscape formation time natural science students was higher than liberal arts students. The research measured gender boys higher than girls. Fourth, the students on the landscape and geological time was found to have a number of misconceptions. This appears to be due to the students to feel difficulty in thinking of the concept because the need to understand the abstract geologic time. Therefore, it is necessary just to hold misconceptions about the concept of geology students have through the study of the landscape and geological time.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.522-524
• /
• 2003

This paper presents the interactive method of showing geological hazard maps and other related information using the new GIS software developed at the Geological Survey of Japan. The main purpose of the software is to easily provide information about geological hazards to a wide range of users. The software incorporates spatial and a-spatial data to interactively present the time, locations and extent of occurrence of geological hazards and other related information. Queries for hazard information can be easily done. Simulations of the occurrence of a particular geological event like the spread of volcanic ash during major volcanic eruptions can also be easily shown.

• Geomechanics and Engineering
• /
• v.28 no.4
• /
• pp.421-435
• /
• 2022

The necessity of estimating the time and cost required for tunnel construction has led to extensive research in this regard. Since geological conditions are significant factors in terms of time and cost of road tunnels, considering these conditions is crucial. Uncertainties about the geological conditions of a tunnel alignment cause difficulties in planning ahead of the required construction time and costs. In this paper, the continuous-space, discrete-state Markov process has been used to predict geological conditions. The Monte-Carlo (MC) simulation (MCS) method is employed to estimate the construction time and costs of a road tunnel project using the input data obtained from six tunneling expert questionnaires. In the first case, the input data obtained from each expert are individually considered and in the second case, they are simultaneously considered. Finally, a comparison of these two modes based on the technique presented in this article suggests considering views of several experts simultaneously to reduce uncertainties and ensure the results obtained for geological conditions and the construction time and costs.

• Korean Journal of Remote Sensing
• /
• v.39 no.1
• /
• pp.65-76
• /
• 2023

The Gamma Portable Radar Interferometer (GPRI) is a ground-based real aperture radar (RAR) that can acquire images with high spatial and temporal resolution. The GPRI ground-based radar used in this study composes three antennas with a Ku-band frequency of 17.1-17.3 GHz (1.73-1.75 cm of wavelength). It can measure displacement over time with millimeter-scale precision. It is also possible to adjust the observation mode by arranging the transmitting and receiving antennas for various applications: i) obtaining differential interferograms through the application of interferometric techniques, ii) generation of digital elevation models and iii) acquisition of full polarimetric data. We introduced the hardware configuration of the GPRI ground-based radar, image acquisition, and characteristics of the collected radar images. The interferometric phase difference has been evaluated to apply the multi-temporal interferometric SAR application (MT-InSAR) using the first observation campaigns at Pusan National University in Geumjeong-gu, Busan.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.10a
• /
• pp.31-33
• /
• 2005

• Geomechanics and Engineering
• /
• v.38 no.1
• /
• pp.69-77
• /
• 2024

The development of shield-driven cross-river tunnels in China is witnessing a notable shift towards larger diameters, longer distances, and higher water pressures due to the more complex excavation environment. Complex geological formations, such as fault and karst cavities, pose significant construction risks. Real-time adjustment of shield tunneling parameters based on parameter prediction is the key to ensuring the safety and efficiency of shield tunneling. In this study, prediction models for the torque and thrust of the cutter plate of ultra-large diameter slurry shield TBMs is established based on integrated learning algorithms, by analyzing the real data of Heyan Road cross-river tunnel. The influence of geological complexities at the excavation face, substantial burial depth, and high water level on the slurry shield tunneling parameters are considered in the models. The results reveal that the predictive models established by applying Random Forest and AdaBoost algorithms exhibit strong agreement with actual data, which indicates that the good adaptability and predictive accuracy of these two models. The models proposed in this study can be applied in the real-time prediction and adaptive adjustment of the tunneling parameters for shield tunneling under complex geological conditions.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.257-267
• /
• 2006

The earth retaining wall systems for excavation works in a populated urban area or a poor soil deposit can be limited due to various restriction. Thus there are various methods to be applied for them such as the soldier pile method, the diaphragm wall with counterfort and so on. In this study, the self-supported earth retaining wall using the DCM(Deep Cement Mixing) method, including its merits, demerits and some important characteristics occured in the design and the construction stage, was introduced. It might be reference for the other design and construction procedures using the DCM method.

• Tunnel and Underground Space
• /
• v.5 no.3
• /
• pp.214-222
• /
• 1995

Geological events which are undetected by the surface geophysical or geological survey phase can cause many problems, especially when the tunnel is excavated by TBM. To detect the geological events ahead of tunnel face, a seismic method applied from VSP method is used. Generally uniaxial geophone has been used in surface seismic survey. But this time, triaxial geophone is used to reduce the noise of tunnel wave. DME(Dip moveout Enhancement) filter and diffraction stack method are used. Applying these techniques to the road tunnel in construction, it is proved that the geological events ahead of tunnel face is fairly well predicted. From the seismic trace, Vp and Vs which are related to the rock property can be also obtained. Rock property and proper support design can be dedced from these parameters.

• Geomechanics and Engineering
• /
• v.31 no.5
• /
• pp.519-527
• /
• 2022

Shear failure in soil is the primary cause of most geotechnical structure failures or instability. Soil water content is a significant factor affecting soil shear strength. In this study, the shear strength of samples with different water contents was tested. The shear strength, cohesion, and internal friction angle decreased with increasing water content. Based on the variation of cohesion and internal friction angle, the water content zone was divided into a high-water content zone and low-water content zone with a threshold water content of 15.05%. Cohesion and internal friction angle have a good linear relationship with water content in both zones. Environmental Scanning Electron Microscopy (ESEM) test presented that the aggregates size of the compacted loess gradually increases with increasing water content. Meanwhile, the clay in the compacted loess forms a matric that envelops around the surface of the aggregates and fills the inter-aggregates pores. A quantitative analysis of bound water and free water under different water contents using a nuclear magnetic resonance (NMR) test was carried out. The threshold water content between bound water and free water was slightly below the plastic limit, which is consistent with the results of shear strength parameters. Combined with the T2 distributions obtained by NMR, one can define a T2 relaxation time of 1.58 ms as the boundary point for bound water distribution without free water. Finally, the effects of bound water and free water on shear strength parameters were analyzed using linear regression analysis.

• Geomechanics and Engineering
• /
• v.16 no.2
• /
• pp.113-124
• /
• 2018

Under repeated loading, the residual stresses within the subgrade and subsoil can accelerate the deformation of the road structures. In this paper, a series of laboratory cyclic loading model tests and small-scale model tests were conducted to investigate the dynamic stress response within soils under different loading conditions. The experimental results showed that a dynamic stress accumulation effect occurred if the soil showed cumulative deformation: (1) the residual stress increased and accumulated with an increasing number of loading cycles, and (2) the residual stress was superimposed on the stress response of the subsequent loading cycles, inducing a greater peak stress response. There are two conditions that must be met for the dynamic stress accumulation effect to occur. A threshold state exists only if the external load exceeds the cyclic threshold stress. Then, the stress accumulation effect occurs. A higher loading frequency results in a higher rate of increase for the residual stress. In addition to the superposition of the increasing residual stress, soil densification might contribute to the increasing peak stress during cyclic loading. An increase in soil stiffness and a decrease in dissipative energy induce a greater stress transmission within the material.