• Tunnel and Underground Space
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• v.21 no.3
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• pp.216-224
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• 2011

In this study, Class II behavior of rock failure process under uniaxial and biaxial compression has been numerically simulated using bonded particle model. Class II behavior of rock was simulated by radial strain controlled uniaxial and biaxial compression tests using a suggested method of ISRM. Micro-parameters used in the simulation were determined based on the laboratory uniaxial compression tests carried out at ${\"{A}}sp{\"{o}}$ Hard Rock Laboratory, Sweden. Class II behavior of ${\"{A}}sp{\"{o}}$ rock was effectively simulated using newly proposed numerical technique in this study, and the results of numerical simulations show good similarity with the complete stress-strain curves for Class II behavior obtained from the laboratory tests.

• Geomechanics and Engineering
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• v.36 no.1
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• pp.51-69
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• 2024

Currently, composite lining mountain tunnels in China are generally classified based on the [BQ] method for the surrounding rock grade. Increasingly, tunnel field construction is replicated indoors for scale down model tests. However, the development of analogous materials for model tests of composite lining tunnels with different surrounding rock grades is still unclear. In this study, typical Class III and V surrounding rock analogous materials and corresponding composite lining support materials were developed. The whole processes of excavation-support dynamics of the mountain tunnels were simulated. Data on the variation of deformations, contact pressures and strains on the surrounding rock were obtained. Finally, a comparative analysis between model tests and numerical simulations was performed to verify the rationality of analogous material development. The following useful conclusions were obtained by analyzing the data from the tests. The main analogous materials of Class III surrounding rock are barite powder, high-strength gypsum and quartz sand with fly ash, quartz sand, anhydrous ethanol and rosin for Class V surrounding rock. Analogous materials for rockbolts, steel arches are replaced by aluminum bar and iron bar respectively with both shotcrete and secondary lining corresponding to gypsum and water. In addition, load release rate of Class V surrounding rock should be less than Class III surrounding rock. The fenestration level had large influence on the load sharing ratio of the secondary lining, with a difference of more than 30%, while the influence of the support time was smaller. The Sharing ratios of secondary lining in Class III surrounding rock do not exceed 12%, while those of Class V surrounding rock exceed 40%. The overall difference between the results of model tests and numerical simulations is small, which verifies the feasibility of similar material development in this study.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.4
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• pp.1-11
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• 2001

This study was carried out to analyze the characteristics of forest environmental and stream morphological factors by using the quantification theory(I) for evaluation of the watershed stability. Present annual mean sediment yield of erosion control dams were investigated in 167 sites of erosion control dam constructed during 1986 to 1999 in Gyeongbuk. The results obtained from this study were summarized as follows; According to the coefficients of partial correlation, each factor affecting to sediment was shown in order of gravel contents, number of first streams order, number of total streams, length of total streams, forest type, length of main stream, parent rock, stand age, soil texture, stream order, slope gradient, soil depth and aspect. Descriptions of class I were as follow; Igneous rock of parent rock, hardwood stands of forest type, less than 20 year of stand age, less than 30cm of soil depth, sandy clay loam of soil texture, more than 41% of gravel contents, south~east of aspect, 2,501~3,500m of length of main stream, 21~25 of number of total streams, 5,501~10,000m of length of total streams, 3 or more than 4 of stream order, more than 16 of number of first stream orders and more than $31^{\circ}$ of slope gradient. Descriptions of class II were as follow; Metamorphic rock of parent rock, coniferous stands of forest type, more than 25 year of stand age, 31~40cm of soil depth, silt loam of soil texture, 11~20% of gravel contents, north~west of aspect, 2,501~3,500m of length of main stream, 16~20 of number of total streams, 3,501~5,500m of length of total streams, 3 of stream order, 11~15 of number of first stream orders and more than $31^{\circ}$ of slope gradient. Descriptions of class III were as follow; Sedimentary rock of parent rock, mixed stands of forest type, more than 25 year of stand age, more than 51cm of soil depth, silty clay loam of soil texture, less than 10% of gravel contents, south~west of aspect, less than 500m of length of main stream, less than 5 of number of total streams, less than 1,000m of length of total streams, less than 1 of stream order, less than 2 of number of first stream orders and less than $25^{\circ}$ of slope gradient. The prediction method of suitable site for erosion control dam divided into class I, II, and III for the convenience of use. The score of class I evaluated as a very unstable area was more than 8.4494. A score of class II was 8.4493 to 6.0452, it was evaluated as a moderate stable area, and class III was less than 6.0541, it was evaluated as a very stable area.

• Journal of the Korean Society of Earth Science Education
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• v.6 no.1
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• pp.69-77
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• 2013

The study aims to figure out pre-service elementary teachers' knowledge understanding on 'stratum and rock' as well as teaching-learning types on the same topic. A total of 65 seniors in an advanced science education course at B University of Education joined the research to fulfill the purpose above. With PCK classification framework, the study examined pre-service teachers' knowledge understanding on 'stratum and rock' while it analyzed how the teachers would teach the given topic to students. The results of the study are presented as follows. First, it was observed that the pre-service elementary teachers have a great understanding on 'stratum and rock' that would be taught via a science textbook for elementary fourth graders. However, regarding terms in 'shale and limestone', they appeared to have a relatively short understanding. Second, PCK elements of the pre-service teachers related to 'stratum and rock' were analyzed and according to the results, the teachers would be interested in teaching model selecting in the teaching-learning strategy field while they would be well aware of how important it is for them to perform an experiment in a teaching process. The teachers also appeared to understand that the teacher question can be mutual complementary during class. However, it turned out that the teachers would have a very much low understanding on learners' prior knowledge as they particularly believe that learning could be significantly affected by the learners' perception level as well as their learning interest and motive. Third, the pre-service elementary teachers were told to design teaching plans on 'stratum and rock' so that the study could find out what learning-teaching methods the teachers would adopt to teach the topic. It was learned that the teachers would proceed with the class basically by giving the learners a descriptive explanation on the topic and also by using pictures and drawings to enhance the learners' understanding during the class.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.330-354
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• 2024

In site characterization of high-level radioactive waste, discontinuity(joint) distribution and rock mass classification, which are key evaluation parameters in the rock engineering field, were evaluated using deep boreholes in the Wonju granite and Chuncheon granite, which belong to Mesozoic Jurassic era. To evaluate joint distribution characteristics, fracture zones and joint surfaces extracted from ATV data were used, and major joint sets were evaluated along with joint frequency according to depth, dip direction, and dip. Both the Wonju and Chuncheon granites that were studied showed a tendency for the frequency of joints to increase linearly with depth, and joints with high angles were relatively widely distributed. In addition, relatively large amounts of weathering tended to occur even in deep depth due to groundwater inflow through high-angle joints. RQD values remained consistently low even at considerable depth. Meanwhile, joint groups with low angles showed different joint characteristics from joint sets with high angles. Rock mass classification was performed based on RMR system, and along with rock mass classification for 50 m intervals where uniaxial compressive strength was performed, continuous rock mass classification according to depth was performed using velocity log data and geostatistical techniques. The Wonju granite exhibited a superior rock mass class compared to the Chuncheon granite. In the 50 m interval and continuous rock mass classification, the shallow part of the Wonju granite showed a higher class than the deep part, and the deep part of the Chuncheon granite showed a higher class than the shallow part.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.213-224
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• 2005

The safety factor of a tunnel considering the failure of supports is important because the failure of supports might cause the collapse of the tunnel. In the previous studies, shotcrete was modelled as beam elements and the failure of the shotcrete was checked according to the allowable working stress concept. In this study, shotcrete was modelled by both beam elements and continuum (elasto-plastic) elements. Safety factors of tunnels were estimated by two dimensional numerical analysis with varying rock mass class, coefficient of lateral pressure, thickness of shotcrete, rock bolt reinforcement and excavation method. Also the study suggested not only a proper amount of supports but also modelling method.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.3
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• pp.225-234
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• 2012

The Purpose of this study is searching the effect of the flow level increasing by using flow learning on scientific achievement and attitude toward science in 4rd grade elementary school student's scientific learning factors, and the better way to approach scientific institude than now in used. Participants included 52 elementary school students. For this study, two classes were divided into experimental class and control class. The control class takes a regular instructions and the experimental class takes a flow learning instructions. Two chapter were selected, 'Plant's World' and 'Fossil and Rock', for this study. Students were treated for 18 hours. The results were as follows: First, flow learning related program about plant's world, fossil and rock is increasing 4rd grade elementary school students' flow level in science class. Second, students are not increasing their scientific achievement according to increasing their flow level. Third, students are not increasing their attitude toward science according to increasing their flow level. But in attitude toward scientific inquiry, adoption of attitude toward science and preference of job related science subordinated, students are increasing subordinate factors of attitude toward science.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.494-507
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• 2021

With the increasing use of TBM, research has recently been conducted in Korea to analyze TBM data with machine learning techniques to predict the ground in front of TBM, predict the exchange cycle of disk cutters, and predict the advance rate of TBM. In this study, classification prediction of rock characteristics of slurry shield TBM sites was made by combining traditional rock classification techniques and machine learning techniques widely used in various fields with machine data during TBM excavation. The items of rock characteristic classification criteria were set as RQD, uniaxial compression strength, and elastic wave speed, and the rock conditions for each item were classified into three classes: class 0 (good), 1 (normal), and 2 (poor), and machine learning was performed on six class algorithms. As a result, the ensemble model showed good performance, and the LigthtGBM model, which showed excellent results in learning speed as well as learning performance, was found to be optimal in the target site ground. Using the classification model for the three rock characteristics set in this study, it is believed that it will be possible to provide rock conditions for sections where ground information is not provided, which will help during excavation work.

• Journal of the Korean Society of Costume
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• v.58 no.6
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• pp.69-84
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• 2008

Considering that star reflects the image of current society, analyzing fashion of celebrity is to read ideal type and demands of beauty of the era. Especially the rock music-represents youth culture that last on present day-born in 1960's, and it is considered to a significant decade in pop music history. Thus this research will analysis rock star's fashions in iconological view of E. Panofsky. The aim of this document is Clarifying how the fashion of pop stars appeared and what formed its worth. As a result of analyzing fashions of rock star in 1960's, it is available to find these sameness and difference. The Mods borrowed images of the past, and introduce the elite modernism and shows very urban style. The Folky and the Psychedelic showed post-structuralism propensity against industrial society, in the case of the Folky it induced styles that symbolize labor class to realize social worth. And as an aftereffect of war and repulsion of commercial worth, they embody nature-returning peasant look so that it shows pastoral mood in total. The Psychedelic express somewhat struggling escapism and it generated illusionary images with quests to superego and glorification to psychedelic status. The Folky and the Psychedelic are same in the side of introducing existentialism, this occurred by using ethnic factor. But the Folky showed plain outlook by pop propensity, on the other hand, the Psychedelic showed magnificent outlook such as optical art, pop art, and futurism ought to express merrymaking culture. And common feature of these is introduction of unisex mod which is came after the change of gender role. Thus each star or group has professed special ideology into their culture and it is reflected to acts which is including music and dress style. This affair is analyzed like these two things. The mass of people schemes their identity with inducing special ideology to their culture at the first. And the purpose to archive cultural hegemony in inter-social class at the next.

• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.415-424
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• 2006

This study was carried out to analyze the characteristics of forest watershed factors by using the quantification theory(I) for evaluation and prediction of the failure hazard area. Present $sediment(m^3/yr/ha)$ of erosion control dams were investigated in 95 sites of erosion control dam constructed during 1986 to 1999 in Gyeongnam province. The results obtained from this study were summarized as follows; General condition of class I(Very hazard area) were as follow; Igneous rock in parent rock, coniferous in forest type, below 20year in stand age, below 30cm in soil depth, SCL in soil texture, $31{\sim}40%$ in gravel contents, $S{\sim}E$ in aspect, $2,501{\sim}3,600m$ in length of main stream, $26{\sim}30$ in number of total streams, $6,601{\sim}10,000m$ in length of total streams, over 3 in stream order, over 16 in number of first streams order and over $31^{\circ}$ of slope gradient. General condition of class IIl(hazard area) were as follow; Metamorphic rock in parent rock, hardwood in forest type, over $21{\sim}24year$ in stand age, $31{\sim}40cm$ in soil depth, SiCL or SCL in soil texture, $11{\sim}20%$ in gravel contents, $S{\sim}W$ in aspect, $1,501{\sim}2,600m$ in length of main stream, $6{\sim}10$ in number of total streams, $3,501{\sim}5,500m$ in length of total streams, 2 in stream order, $6{\sim}10$ in number of first streams order and over $31^{\circ}$ of slope gradient. General condition of class III(Un hazard area) were as follow; Sedimentary rock in parent rock, mixed in forest type, over 25year in stand age, $41{\sim}50cm$ in soil depth, SiCL in soil texture, below 10% in gravel contents, $N{\sim}W$ in aspect, below 500m in length of main stream, below 5 in number of total streams, below 1,000m in length of total treams, below 1 in stream order, below 2 in number of first streams order and below $25^{\circ}$ of slope gradient. The prediction method of suitable for failure hazard area divided into class I, II, and III for the convenience of use. The score of class I evaluated as a very hazard area was over 4.8052. A score of class II was 4.8051 to 2.5602, it was evaluated as a hazard area, and class III was below 2.5601, it was evaluated as a un hazard area.