• 대한치과보철학회:학술대회논문집
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• 2000.04a
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• pp.21-21
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• 2000

• Magazine of korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.11-20
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• 2015

• Magazine of korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.51-54
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• 2019

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.431-450
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• 2011

When a circular vertical shaft is constructed below the groundwater level, additional forces caused by groundwater flow besides horizontal effective stresses will act on the wall. The inward direction of the groundwater flow will be inclined to the vertical wall and its direction will change depending on the wall depth. In this paper, to figure out the effect of seepage forces acting on the circular vertical shaft, the slope of the inclined flow varying with the depth is divided into vertical and horizontal components to derive the coefficient of earth pressure considering the seepage pressure and to obtain the vertical stress by taking the seepage pressure into account. The control volume in this study is assumed to be the same with that of the dry ground condition within which the earth pressure is acting on the wall by the creation of the plastic zone during shaft excavation. An example study shows that the vertical stress increases by about 1.4 times and the horizontal earth pressure increases up to 2.5 times compared to the dry ground condition. The estimated values from the proposed equation considering seepage forces and the calculated values from numerical analysis with "effective stress plus seepage force" show similar values, which verifies appropriateness of the proposed equation to estimate the earth pressure under the seepage condition.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.114-120
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• 2006

The main purpose of this study is to apply spatial analysis using semivariograms to small-loop electromagnetic survey data to assess the extent of seawater intrusion in an experimental watershed. To indicate the extent of seawater intrusion over the study area, vertical electrical soundings at 33 points and electrical conductivity logging in two wells were conducted. From the correlation between resistivities obtained by inversion and the depth of the aquifer at the two wells, the region of seawater intrusion was identified and demonstrated by electrical conductivity logging results obtained over two years. To measure the variation of apparent conductivity with depth, an electromagnetic survey in six frequency bands was adopted. Apparent conductivity mapping with spatial analysis using semivariograms is an effective technique for identifying the region of seawater intrusion at shallow depth.

• Journal of Korean Association for Spatial Structures
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• v.12 no.3
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• pp.71-78
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• 2012

The dynamic behavior of spatial structures is different depending on the aspect ration of arch structure, as the rise-span ratio or open-angle, and these spatial structures show differently the character of seismic response in accordance with stiffness and connection of the lower support structures that are directly influenced by earthquake. Therefore, in this paper, dynamic analysis is conducted for seismic response of single layer arch structures by the influence of column's stiffness and connection, to reflect the different vertical and horizontal vibration mode of single layer arch structures. The vertical response of single layer arch structures is more influence by lower columns and the influence of column's connection rotational stiffness is not large, except to the hinged connections.

• Journal of Cadastre & Land InformatiX
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• v.49 no.2
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• pp.57-66
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• 2019

Recently, as a part of the production of spatial information by smart cities, three-dimensional reproduction of structures for reverse engineering has been attracting attention. In particular, terrestrial LiDAR is mainly used for 3D reproduction of structures, and 3D reproduction research by UAS has been actively conducted. However, both technologies produce blind spots due to the shooting angle. This study deals with vertical structures. 3D model implemented through SfM-based image analysis technology using UAS and reproducibility and effectiveness of 3D models by terrestrial LiDAR-based laser scanning are examined. In addition, two 3D models are merged and reviewed to complement the blind spot. For this purpose, UAS based image is acquired for artificial rock wall, VCP and check point are set through GNSS equipment and total station, and 3D model of structure is reproduced by using SfM based image analysis technology. In addition, Through 3D LiDAR scanning, the 3D point cloud of the structure was acquired, and the accuracy of reproduction and completeness of the 3D model based on the checkpoint were compared and reviewed with the UAS-based image analysis results. In particular, accuracy and realistic reproducibility were verified through a combination of point cloud constructed from UAS and terrestrial LiDAR. The results show that UAS - based image analysis is superior in accuracy and 3D model completeness and It is confirmed that accuracy improves with the combination of two methods. As a result of this study, it is expected that UAS and terrestrial LiDAR laser scanning combination can complement and reproduce precise three-dimensional model of vertical structure, so it can be effectively used for spatial information construction, safety diagnosis and maintenance management.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.57-66
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• 2011

For the lateral load resistance of a RC frame in a medium risk seismic zone, the strength of lower story beams and columns should be larger than those of the upper stories. However, the lateral loads can be accommodated by redistributing design beam moments vertically as well as horizontally so all beams end up with identical strengths. This paper looks at the impact of the vertical redistribution of beam moments to provide identical beam strength over as many floors as possible. Two-bay six-story RC frame was designed with and without vertical beam moment redistribution and its seismic performance were evaluated by using push-over limit analysis and by non-linear time history dynamic analysis. Analytical results show that with the use of vertical beam moment redistribution the increase in the ductility demand is similar to the proportion of moment redistribution applied, but this additional demand is below the ductility capacity of well detailed RC members.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.1
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• pp.49-62
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• 2007

A new earth pressure equation acting on the vertical shafts in cohesionless soils has been proposed by modifying the equations proposed by others. In order to verify the modified equation, model tests which can control uniform wall displacement with depth to radial direction were conducted. Model tests were performed with three different wall friction angles and two different relative densities. The measured values were larger than estimated values when assuming $\lambda=1$ ; smaller than those when assuming $\lambda=1-sin\phi$. The parameter, $\lambda$ is the ratio of tangential stress to vertical stress and is the most critical value in proposed equation. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by reasonably assuming the failure surface of layered soils and using the modified equation. In order to verify the proposed method, in-situ measurement data have been collected from the three in-situ vertical shafts installed in layered soils. Most of earth pressures converted from measured data match reasonably well with estimated values using proposed method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.887-897
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• 2018

3D time history analysis was performed on vertical shaft-tunnel connection to provide insight into the dynamic stress-strain behavior of the connection considering the effects of soil layers, periodic characteristics and wave direction of earthquakes. MIDAS GTS NX based on FEM (Finite Element Method) was used for this study. From this study, it is revealed that the maximum displacement occurred at the upper part of the connection when the long period seismic waves propagate through the tunnel direction in soft ground. Also, stress concentration occurs due to different behaviors of vertical shaft and tunnel, and the stress concentration could be influence for safety on the connection. The results of this study could be useful for the seismic performance design of vertical shaft-tunnel connection.