• Tunnel and Underground Space
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• 제16권1호
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• pp.58-72
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• 2006

In recent years, not only the occurrences but the magnitude of earthquakes in Korea are on an increasing trend and other sources of dynamic events including large-scale construction, operation of hi띤-speed railway and explosives blasting have been increasing. Besides, the probability of exposure fir rock joints to free faces gets higher as the scale of rock mass structures becomes larger. For that reason, the frictional behavior of rock joints under dynamic conditions needs to be investigated. In this study, a shaking table test system was set up and a series of dynamic test was carried out to examine the dynamic frictional behavior of rock joints. In addition, a computer program was developed, which calculated the acceleration and deformation of the sliding block theoretically based on Newmark sliding block procedure. The static friction angle was back-calculated by measuring yield acceleration at the onset of slide. The dynamic friction angle was estimated by closely approximating the experimental results to the program-simulated responses. As a result of dynamic testing, the static friction angle at the onset of slide as well as the dynamic friction angle during sliding were estimated to be significantly lower than tilt angle. The difference between the tilt angle and the static friction angle was $4.5\~8.2^{\circ}$ and the difference between the tilt angle and the dynamic friction angle was $2.0\~7.5^{\circ}$. The decreasing trend was influenced by the magnitude of the base acceleration and inclination angle. A DEM program was used to simulate the shaking table test and the result well simulated the experimental behavior. Friction angles obtained by shaking table test were significantly lower than basic friction angle by direct shear test.

• Tunnel and Underground Space
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• 제17권4호
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• pp.301-310
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• 2007

The prediction of temperature in the workings for the propriety examination for the development of a deep coal bed and the ventilation design is fairly important. It is quite demanding to obtain precise thermal conductivity of rock due to the variety and the complexity of the rock types contiguous to the coal bed. Therefore, to estimate the thermal conductivity corresponding to this geological situation and complex gallery conditions, a computing program which is TemPredict, is developed in this study. It employs Artificial Neural Network and calculates the climatic conditions in galleries. This advanced neural network is based upon the Back-Propagation Algorithm and composed of the input layers that are acceptant of the physical and geological factors of the coal bed and the hidden layers each of which has the 5 and 3 neurons. To verify TemPredict, the calculated result is compared with the measured one at the entrance of -300 ML 9X of Jang-sung production department, Jang-sung Coal Mine. The difference between the results calculated by TemPredict ($25.65^{\circ}C$) and measured ($25.7^{\circ}C$) is only $0.05^{\circ}C$, which is less than the allowable error 5%. The result has more than 95% of very high reliability. The temperature prediction for the main carriage gallery 9X in -425 ML under construction when it is completed is made. Its result is $28.2^{\circ}C$. In the future, it would contribute to the ventilation design for the mine and the underground structures.

• Journal of Korea Water Resources Association
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• 제44권7호
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• pp.565-576
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• 2011

Within a basin, there are potentially multiple locations that can be used as a washland, given their relatively small size when compared with other hydraulic facilities such a dam. However, it is unreasonable to install washlands in all these potential locations due to economic and environmental considerations. In this study, a new methodology for determination of installation priority of washlands is presented. How to integrate the decision variables in this decision making problem has been a key issue in previous studies because a washland can provide many benefits such as flood reduction, agricultural benefit and recreational benefit. In particular, a methodology is needed to integrate all decision variables realistically, properly and reasonably, in situations where there is not sufficient data for direct integration of all these decision variables such as construction cost or benefits a washland can provide. This new methodology aims to suggest how to integrate methodologies used in previous studies. The suggested methodology uses four different rankings which are determined based on a flood reduction effect, a relative significance index, an economic analysis, and a space planning suitability index. These rankings are integrated to determine a final installation priority ranking of washlands by a multi-dimensional scaling method. The new methodology has been applied to the Anseong river basin, to show its applicability, and the application result compared with those of previous studies.

• Land and Housing Review
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• 제5권1호
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• pp.25-34
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• 2014

This study starts from the fact that we need residential complex for the purpose of public interests, rather than for profits, and find a new perspective on the concept of public-oriented residential complex in the cities that had slow growth. In this study, we 1) propose a new concept of the residential complex that can vitalize regional communities and maintain the interest of the public : 'functional-mix', 'social-mix', 'spatial-mix', 2) produce a model simulation based on the development principles including development direction, types of development, and design guidelines, ; six development principles(goal, concept, development type, spatial structure, space element, spatial hierarchy), diversity of housing types, facilities that can vitalize and contribute the regional communities 3) propose practical methods that can realize and promote the proposed concept and model simulation. ; need to amend the housing construction Law.

• Journal of the Korean earth science society
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• 제21권3호
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• pp.208-218
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• 2000

The popularization and the common use of internet are realizing these days thanks to the development of web. Using the web as a teaching instrument is the Web Based Instruction(WBI). WBI, along with constructivism, has a great influence on the present educational society. However, many problems were found in learners' using the numerous WBI programs in cyber space. Above all, the interaction between teachers and learners is not enough, and searching for the materials on web is not easy. It's very difficult for a teacher to design and construct a WBI program in school teaching. But It is not so difficult to design and construct a WBI program based on interaction. Therefore, if a teacher familiar to students in school makes a web page and provides a cyberspace, the students will interact very easily them in the cyberspace. They can use the e-mail, bulletin board or discuss and chat. The cyberspace will make up for the insufficient interaction in school life. But because this program needs all students have proper material condition, there will be another kind of estranged learners. Thus, this problem can be solved by the cheap-popular PC offering movement backed by the government, and other types of projects systematically.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제16권1호
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• pp.744-754
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• 2015

Buddhist temple construction at East Asia is considered one of the most important architecture activities together with the capital city and palace, where the pagoda is positioned at the center of a Buddhist temple as the most important element of Buddhist architecture enshrining Buddha's Sary. Accordingly, this study was performed to examine the procedure of how to build brick pagodas through the stone pagoda's internal structure between $7^{th}{\sim}9^{th}$ century while disassembling and repairing Andong Jotap-ri five-story brick pagoda. As a result, as the brick pagoda destruction phenomenon, there was a slip phenomenon by side forces, member's plastic temperature, and mixed material differences. Second, like a stone pagoda, brick pagoda is classified and constructed by the design and structural parts. According to the analysis, the design part is formed by the most edge brick, and the structure part places stone material at the buffer zone in the design brick from most edge brick and intra-center, i.e., at the space to support a side force while the top weight is vertically led. When building a brick pagoda, putting a wood pole at inside center plays the role as holding parts. In addition, the center axis is connected to the bottom of the steel pole hole, A steel pole hole has holes to safely settle down and decide the position. Because of them, the steel pole is self-loaded, which may be installed by wood rather than immovable steel.

• Tunnel and Underground Space
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• 제16권4호
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• pp.281-287
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• 2006

Intake of groundwater by tunneling in a mountainous area mostly results from groundwater flow through fractured parts of total rock mass. For reasonable analysis of this phenomenon the representative joint groups 1, 2, and 3 have been selected by previous investigations, geological/geophysical field tests and boring works. Three dimensional fractures were generated by the FracMan and MAFIC which is a three dimensional finite element model has been used to analyse a groundwater flow through fractured media. Monte Carlo simulation was applied to reduce the uncertainty of this study. The numerical results showed that the average and deviation of amounts of groundwater intaked into tunnel per unit length were $5.40{\times}10^{-1}$ and $3.04{\times}10^{-1}m^3/min/km$. It is concluded that tunnel would be stable on impact of groundwater environment by tunneling because of the lower value than $2.00{\sim}3.00m^3/min/km$ as previous and present standard on the application of tunnel construction.

• Tunnel and Underground Space
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• 제28권3호
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• pp.258-276
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• 2018

The accurate and quantitative ground information on the hydraulic conductivity characteristics of rock mass is one of the key factors for evaluation of the hydro-geological behaviour of rock mass around an excavated opening under high water pressure. For tunnel and rock structures in seabed, where the sea acts as an infinite source of water, its importance become greater with increasing construction depth below sea level. In this study, to improve the problems related with poor system configuration and incorrect data acquisition of previous hydraulic packer testing equipment, we newly developed an integrated main frame and 30 bar level waterproof downhole sonde apparatus, which were optimized for deep hydraulic packer test in seabed rock mass. Integration of individual test equipment into one frame allows safe and efficient field testing work on a narrow offshore drilling platform. For the integrated type main frame, it is possible to make precise stepwise control of downhole net injection pressure at intervals of $2.0kg_f/cm^2$ or less with dual hydraulic oil volume controller. To ensure the system performance and the operational stability of the prototype mainframe and downhole sonde apparatus, the field feasibility tests were completed in two research boreholes, and using the developed apparatus, the REV(Representative Elementary Volume) scale deep hydraulic packer tests were successfully carried out at a borehole located in the basalt region, Jeju. In this paper, the characteristics of the new testing apparatus are briefly introduced and also some results from the laboratory and in-situ performance tests are shown.

• Tunnel and Underground Space
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• 제28권3호
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• pp.232-246
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• 2018

In this study, the relationship between in situ seismic wave velocities and RMR (rock mass rating) was investigated in a test bed for the examination of the basis of rock classification (RMR) based on seismic wave velocity. The seismic wave velocity showed a monotonous increase with depth. It was also found that there was no systematic correlation between the seismic wave velocity (Vp) and other parameters (RQD, joint spacing, UCS, rock core Vp, and RMR) collected at the same depth of the same borehole. However, correlative relation was observed among RMR, RQD, and joint spacing. On the other hand, when all the data in the borehole (three holes) are examined without considering the depth, Vp still shows no correlation with RMR parameters (e.g., correlative coefficient for uniaxial compressive strength and joint spacing are 0.039 and 0.091, respectively), but Vp shows weak correlative relation with RMR and RQD (correlative coefficient for RQD and RMR are 0.193 and 0.211, respectively). Thus, it is found that it is difficult to deduce physical properties of rock mass directly from seismic wave velocities, but the seismic wave velocity can be used as a tool to approximate rock mass properties because of weaker correlation between Vp and RMR with RQD. In addition, the velocity value of for soft and moderate rocks suggested by widely used construction standards is slower than that of the observed velocity, implying that the standards need to be examined and revised.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제4권1호
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• pp.17-24
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• 2006

A demonstration facility for advanced spent fuel conditioning process (ACP) is under construction in KAERI. In this hot cell facility, all process equipments and materials are taken in and out only through the rear door. The working table in front of the process rear door is specially designed to be openable for the efficient use of the space. This paper presents the structural safety analysis of the openable working table, for the normal operational load condition and accidential drop condition of heavy object. Both cases are investigated through static and dynamic finite element analyses. The analysis results show that structural safety of the working table is sufficiently assured and the working table is not collapsed even when an object of 500 kg is dropped from the height of 50 cm.