• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.45-50
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• 2009

The differential settlement may be generated by the variation of stresses caused by the soft ground or ground water. The cracks are usually created when the structures are leaned or deformed due to the differential settlement. A grouting method has been mainly used till now to improve the bearing capacity of the ground when the foundation of the structure is deformed by differential settlements. However, when this method is used, it takes too long time to obtain the required strength and the period of the reinforcement effect is not long enough. The advantage of GPCON injection method is to have good mechanical properties and durability, and easy construction. In addition, the GPCON method rapidly fills up the void in soils by injecting some materials into underground and also obtain the increase of bearing and shearing forces due to the expansion. In this paper the restoration capability of the foundation settlement of railway and subway subjected to cyclic loading is analytically and experimentally evaluated using the high density rapidly expansion GPCON in order to investigate the types of deformations and vibrational characteristics.

• Journal of the Korean Geotechnical Society
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• v.18 no.2
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• pp.65-74
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• 2002

The measurement of in-situ stress is essential to estimate the ground displacement and the stress distribution of a tunnel and an underground structure. In this study, the in-situ stress distribution of the Southern Korean peninsula was re-evaluated by the new 380 in-situ data which were determined by overcoring and hydrofracturing methods, and the three-din erosional numerical analysis of tunnelling was performed. The results of in-situ stress distribution show that the distribution of horizontal stress tends to be more irregular in metamorphosed(gneiss) and granite areas than in sedimentary and volcanic areas. The ratio of horizontal to vertical stresses(K-value) in volcanic area is less than 1 below the depth of 150m. The direction and magnitude of three dimensional in-situ stresses were shown simultaneously in a figure for the first time in Korea. The three-dimensional numerical analysis of tunnelling indicates that the orientation and magnitude of displacement around a tunnel are controlled mainly by the difference between the maximum and minimum horizontal stresses.

• Spatial Information Research
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• v.23 no.3
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• pp.113-122
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• 2015

Recently, according to developing advanced construction technologies, buildings has been enlarged such as high-rise buildings or complex buildings associated with underground facilities. The number of indoor activity population has increased very quickly. Because of that, technical requirements for Indoor location based service (Indoor LBS) also have been increased. Although indoor networks have to be constructed for efficient LBSs in indoor space based on OGC IndoorGML, it is not suitable for large and complex space to apply the simple network structure to constructing indoor navigation networks. The indoor navigation network has to be constructed according to logical, physical, and functional constraints for indoor space. In order to do that, subspacing methods are required to partition large and complex indoor space into proper size of subspace. In this paper, we proposed the basic requirements of subspacing in indoor space for creating efficient indoor network, as well the work process of subspacing in indoor space.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.233-247
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• 2005

Most tunnel lining material which has been used in the domestic is a concrete. But many problems as the construction period, the cost, and the crack occurrence for the design, construction, and management were happened in the concrete lining. For this reason, many research institutes like the Korea Highway Corporation recognize the necessity of an alternate material development and grow on the interest for that. So in this study, the seismic behaviour characteristics for the application of the Corrugated Steel Plate Lining in cut-and-cover tunnel are evaluated as several conditions for the backfill height, the cutting slope, and the relative density of backfill soil are changed. The compressive stress which is calculated in the Corrugated Steel Plate Lining by the seismic load is decreased as the backfill height increases and the cut slope grows gentle. Also, the moment shows the tendency of decrease according to the increase of the backfill height. But in the case of the relative density of the backfill soil is small, the moment increases according to the increase of the backfill height and affects the dynamic behaviour characteristic. So it is considered that the relative density of the backfill soil is also the important point. As the result in analyzing the seismic response characteristics of the reinforcement spacing of the Corrugated Steel Plate, the variation in the compressive force is hardly happened, but the moment and the shear force increase on the reinforcement spacing being narrow.

• Korean Journal of Plant Taxonomy
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• v.43 no.3
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• pp.188-195
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• 2013

The morphological characters and scientific names of Korean Artemisia sect. Absinthium were reviewed based on the type specimen, the original description, observation of the living materials and voucher specimens. The form of the habitat, the structure of underground, the leaf shape and capitulum features were valuable characters in identifying the taxa. The sect. Absinthium in Korea was classified as three taxa of A. sieversiana, A. lagocephala, A. fauriei. The illustration and description of each taxa were provided. Particularly, A. fauriei in this section with hair on receptacle and A. fukudo in sect. Abrotanum without hair on receptacle grow in mixed groups on the West shore of Korea. Two species with populations which grow in mixed groups, was observed as being putative hybrid individuals based on morphological characters.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.390-397
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• 2003

A three-dimensional (3D) inversion technique has been developed for interpretation of magnetotelluric (MT) data. The inversion method is based on the linearized least-squares (Gauss-Newton) method with smoothness regularization. In addition to the underground 3D resistivity distribution, static shifts are also treated as unknown parameters in the inversion. The forward modeling is by the staggered-grid finite difference method. A Bayesian criterion ABle is applied to search the optimum trade-off among the minimization of the data misfit, model roughness and static shifts. The method has been applied to several MT datasets obtained at geothermal fields in Japan and other Asian countries. In this paper, two examples will be discussed: one is the data at the Ogiri geothermal area, southwestern Japan, and the other is at the Pohang low-enthalpy geothermal field, southeastern Korea. The inversion of the Ogiri data has been performed stably, resulting in a good fitting between the observed and computed apparent resistivities and phases. The recovered 3D resistivity structure is generally similar to the two-dimensional (2D) inversion models, although the deeper portion of the 3D model seems to be more realistic than that of the 2D model. The 3D model is also in a good agreement with the geological model of the geothermal reservoirs. 3D interpretation of the Pohang MT data is still preliminary. Although the fitting to the observed data is very good, the preliminary 3D model is not reliable enough because the station coverage is not sufficient for a 3D inversion.

• Economic and Environmental Geology
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• v.9 no.1
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• pp.45-73
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• 1976

This study has been made for the enlargement of a previous work of 1964 which was carried out by an author of this work emphasizing the stratigraphy, micropaleontology, depositional environment, and structural tectonics of the studied area. The stratigraphic sequences of the area are groupped into four units: (1) basement of Pre-Cretaceous, (2) lower sediments of Late Cretaceous, (3) upper sediments of Late Cretaceous and (4) igneous rocks of Late Cretaceous and Tertiary (?). The oldest rocks consisting of schists and gneisses of Pre-Cambrian and schistose granite' of Jurassic age are exposed at the base of this area on which the thick Cretaceous sediments were deposited. These old rocks are unconformably overlain by the lower sedimens of Late Cretaceous composed of three members, an alternation of black shale and tuffaceous sediments, fine tuff and rhyollite flow in ascending order. The oily material was found from the black shales of the alternation m"ember as semi-solid greaselike material, oily order and microscopic granular spherical material and oily stain. The lower sediments are also overlain, in low-angleunconfromity, by the 'upper sediments having three members, an alternation of volcanic conglomerate and andesitic tuff, rhyollitic tuff and andesite flow in the same order. The igneous suit of diabase, diorites, biotite granite, porphyritic granite and porphyries of the latest Cretaceous and small exposure of pitchstone of Tertiary (?) intruded into the pre-existed rocks above mentioned. Considerable amount of ostra- coda microfossils have been chemically extracted from the black shales of the lower sediments and the identification of the fossils suggests that the depositional environment of the sediments were under fresh or brackish water condition. The distribution of the geology and its tectonic data also suggest a combination of dome and basin structures in the area of San-i peninsula and Jin-do as shown in fig. 8. Between these two units an anticlinal structure was constructed. As a result of this study, a seismic survey in a district between U-su-yong and north coast of Jin-do is recommended to determine the underground features.

• Explosives and Blasting
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• v.24 no.1
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• pp.63-69
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• 2006

Building tunnels means dealing with what rock is encountered. Relocation of the site of the underground structure is rarely possible. Tunneling engineers and miners have to cope with the quality of the rock mass as it is. Different tunneling philosophies and different rock classification methods have been developed in various countries. Most of the rock classification methods are based on the response of the rock mass to the excavation. Tunnel support requirements could be assessed analytically, supplemented by rock mass classification predictions, and verified by measurements during construction. Rock mass classifications on their own should only be used for preliminary, planning purposes and not for final tunnel support. Design of blast pattern in tunneling projects in Korea is also mostly prepared according to the general rock classification methods such as RMR or Q. They, however, do not take into account the blast performance, and as a consequence, produce poor blasting results. In this paper, the methods of general rock classification and blast design for tunnel excavation in Korea are reviewed, and efforts to develop a new classification method, reflecting the blasting performance, are presented.

• Tunnel and Underground Space
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• v.27 no.5
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• pp.253-262
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• 2017

The purpose of this paper is to analyze the crack characteristics by performing the compression test of the rock and concrete specimens. The experiments are carried out by using strain sensors which can measure length change and the AE sensor which can detect the elastic wave from the crack. The crack volumetric strain calculated from measured strain is shown in different shape on the rock and the concrete specimens. This is because the specimens have a different degree of brittleness. However, the crack volumetric strain associated with the fracture and damage was similar to accumulated AE energy of the two specimens. This means that the AE sensor can assess damage in real time without damaging the structure.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.58-68
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• 2017

According to the development of optical technology, the capacity of LIDAR equipments has been greatly improved to get rock mass characteristics precisely and accurately enough and it has been lightened and popularized so that it can be easily used in the field. In this study, we examined the applicability of roughness measurement for joints in a rock slope using LIDAR technique. A triangular irregular network was constructed using LIDAR and a patch, which is a plane structure of discontinuity on rock mass measured from LIDAR scanning, was extracted to estimate the roughness of the rock slope. Four different kinds of roughness parameters were analyzed to find out their correlation with JRC for various point intervals. Among them, $R_s$ parameter was used to measure the roughness of a patch. Regression analysis between four roughness parameters and JRC with respect to point interval was performed. All the roughness parameters decreased with the increase of point interval. In addition, the parameter value showed greater decrease for rougher surfaces. A method of roughness measurement using $R_s$ parameter on rock slope discontinuities was suggested which showed slight overestimation of the real roughness value.