• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.141-146
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• 2016

Geotechnial engineering projects that requires excavation activity can cause massive ground deformation and this can damage adjacent structures. Depending on the engineering characteristics of ground material and the excavation depth, the ground movement is various. To overcome this issue, the ground deformation is monitored by multiple sensors. Typically, an inclinometer is installed behind the support wall. In this paper, we present an adaptive duty-cycling control mechanism using wireless sensors for monitoring ground deformation in excavations. The proposed mechanism dynamically adjusts the sleep time based on the urgency degree of sensed data from inclinometer. Through analytical evaluation of expected latency time, we confirm our adaptive duty-cycling mechanism has lower latency compared with periodic duty-cycling mechanism under variable conditions.

• Geotechnical Engineering
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• v.11 no.1
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• pp.63-78
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• 1995

Recently, in order to utilize more effectively underground space, deep excavations have been performed on building or subway construction in urban areas. In such excavations, anchors have been used to support the excavation retaining walls because the anchored excavation could provide wide working space for underground construction. The purpose of this paper is to establish empirical equations to be able to estimate the earth pressures acting on anchored excavation retention walls, based on the investigation of field measuring results, which were obtained from twenty seven building construction sites. The prestressed anchor force was measured by load cells which were attached to the anchor head, while the horizontal displacement of excavation walls were measured by inclinometers which were installed right'behind the retention walls. The lateral earth pressures acting on the anchored retention walls, which were estimated from both the measured anchor forces and the horizontal displacement of the walls, showed a trapezoidal distribution. There was some difference between the measured earth pressures acting on the anchored retention walls and the empirical earth pressures given by several empirical equations. Thus, the lateral earth pressures acting on anchored retention walls would be estimated by these empirical equations with some modifications.

• Journal of the Korean Geotechnical Society
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• v.22 no.2
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• pp.19-28
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• 2006

Long-term field observations were performed in three excavation sites in order to investigate the displacement behavior of adjacent ground during overall excavation procedure, where the depths of deep excavations were 15 m$\∼$29 m. In this study, ground settlements and lateral displacements of braced wall measured during installation of retaining wall and removal of bracing were specially focused to evaluate the behavior quantitatively according to three-stage-divided procedure, i.e. pre-excavation, main excavation, and removal of bracing. Through field measurements on three excavation sites, lateral displacements induced during removal of bracing are approximate to 40$\%$ of the amount found during main excavation stage and additional adjacent ground deformation during post-excavation procedure ranges from 18$\%$ to 33$\%$ of that found during main excavation stage, based on the settlement volume. In conclusion, it was quantitatively identified in this study that the deformations of adjacent ground during pre- and post-excavation stage were not negligible.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.559-563
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• 2024

Currently, in Korea, large-scale, deep excavations are being carried out adjacent to structures due to overcrowding in urban areas. for adjacent excavations in urban areas, it is very important to ensure the safety of earth retaining structures and underground structures. accordingly, an automated measurement system is being introduced to manage the safety of subway tunnel structures. however, the utilization of automated measurement system results is very low. existing evaluation techniques rely only on the maximum value of measured data, which can overestimate abnormal behavior. accordingly, in this study, a vast amount of automated measurement data was analyzed using the Gaussian probability density function, a technique that can quantitatively evaluate. highly reliable results were derived by applying probabilistic statistical analysis methods to a vast amount of data. therefore, in this study, the safety evaluation of subway tunnel structures due to adjacent excavation work was performed using a technique that can process a large amount of data.

• Korean Journal of Heritage: History & Science
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• v.52 no.2
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• pp.20-37
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• 2019

Three Inter-Korea summits and a North Korea-USA summit that were previously unexpected provide a basis for an optimistic outlook for the future development of Korean archaeology. While Korean archaeology has witnessed a great advance since the mid-20th century, it also exhibits significant weaknesses in explaining cultural changes in prehistory and the early historical period in the Korean Peninsula due to the paucity of information on archaeological evidence of North Korea. Recent development of favorable conditions for research and excavations of North Korean cultural heritage could be a valuable opportunity for Korean archaeology to overcome the current adversity. Especially, given the expected large-scale SOC industrial project in North Korea, we need to prepare for the systematic research and excavation of archaeological materials. The present essay attempts to provide a suggestion for the joint archaeological expeditions to excavate and manage cultural resources in North Korea based on a critical review of previous salvage excavations in South Korea, such as those conducted before the construction of the Korean rapid transit railway system (KTX). We suggest that professional archaeologists should be included in the project and oversee the planning and design of road and railway constructions and other SOC projects in order to minimize the cost of trial and error processes that were well exemplified by the KTX salvage excavations. The Korean Archaeological Society and North Korean Archaeological Society may organize a common association that will supervise joint archaeological expeditions. Importantly, The Korean Archaeological Society and other related institutions should prepare to build an organization that conducts impending archaeological excavation in North Korea. While we likely face challenges and difficulties during the various stages of archaeological research and excavations in North Korea, only through thorough and systematic preparation can we avoid the destruction of valuable cultural heritage and find an opportunity for the further development of Korean archaeology.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.77-84
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• 2003

Deep excavations in the urban areas have been frequently going on in large scale. Soil-nailing and Earth-anchor supporting methods are generally used in deep excavation. These construction methods cause ground disturbances during drilling process, and damages of adjacent structures and ground due to the differential settlement throughout construction period, and unexpected behaviors of supporting system according to the characteristics of drilling machine and ground condition. This article introduces two actual examples of adjacent deep excavation for the construction of university buildings in granitic Seoul area. The important results of construction and measurements obtained using Crawler drilling machine for Soil-nailing and Earth-anchor supporting methods are summarized. And some suggestions are given to improve and develop the technique of design and construction in the deep excavation projects having similar ground condition and supporting method.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.69-76
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• 2003

This paper presents the prediction of deep excavation-induced ground surface movements using artifical neural network(ANN) technique, which is of prime importance in the perspective of damage assessment of adjacent buildings. A finite element model, which can realistically replicate deep excavation-induced ground movements was employed to perform a parametric study on deep excavations with emphasis on ground movements. The result of the finite element analysis formed a basis for the Arificial Neural Network(ANN) system development. It was shown that the developed ANN system can be effecting used for a first-order prediction of ground movements associated with deep-excavation.

• Geomechanics and Engineering
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• v.5 no.2
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• pp.99-118
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• 2013

Construction of the extension project of the Bangkok MRT Blue Line underground railway was recently started in 2011. The construction of approximately 5 km long underground tunnel and 4 deep excavations of underground station are considered to be the most important geotechnical works. The pressuremeter was selected as a high-quality in situ testing of the soil to evaluate design parameters for the project. In addition, other field and laboratory tests such as vane shear and $CK_0U$ triaxial tests were included in the investigation programme. This paper aims to present the ground conditions encountered along the MRT Blue Line extension project as well as the site investigation and interpretation techniques with particular focus on the pressuremeter tests. The results are also compared with the pressuremeter investigation from the previous Bangkok MRT project.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.166-178
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• 1991

Using FLAC, which is an explicit finite difference code written for analysis of problems in geotechnical engineering, a particular example 2 in the Korean Geothechnical Society News has been analysed. The elastoplasticity formulation in FLAC assumes an elastic, perfectly plastic solid in plane strain which conforms to a Mohr-Coulomb yield condition. During tunnel excavations by stages, stresses and diaplacements in region around the tunnel varies according to distance from the face of tunnel and installation of tunnel supports, and soon. In this analysis, the three dimensional support effect of the rock mass during the process of excavation is simulated by using the stress distribution method, and varying the material constants of shotcrete in each stage also considered. The maximum convergency is occured at the crown of the tunnel and estimated to be about 12mm.

• Geotechnical Engineering
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• v.9 no.1
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• pp.59-68
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• 1993

In deep excavations for creation of underground spaces, it would be difficult to predict earth pressure, especially multilayered ground including rock strata. The earth pressures and displacements on the retention walls are measured by load cell, strain gauge and inclinometer which were installed at struts or anchors at 4 deep excavation sites in Seoul area. In this paper, the measured earth pressure from the struts or anchors are compared with Peck's empirical values, and the coefficient of the earth pressures for each strata and horizontal wall displacement are investigated. The coefficient of earth pressure distribution, a(0.65zka), in the flexible and the rigid walls was about 74% and 88% of Peck's value respecitively. The measured earth pressure distributions for the 4 sites showed about 70%∼80% of Peck's empirical values and the average earth pressure coefficients based on the measured data were 0.3 for the felted layer, 0.23 for the weathered rock and 0.19 for the weak rock. The maximum w리1 displacements were found to be less 0.2% of excavation depth.