• Spatial Information Research
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• v.12 no.3
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• pp.275-283
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• 2004

In order to effectively, and accurately assess seawater intrusion in coastal area, multidisciplinary data including geophysical, well logging, and hydrogeochemical data should be managed in systematical way. Such systematical management of data is critical key to improve the re-usability of the data as well as the accuracy of the assessment by means of providing a method of synthetic analysis. Therefore, for systematical management of multidisciplinary data in seawater intrusion problem, we have developed a database management system and 3-D visualization interface based on geographic information system in this, study. All geophysical survey, well logging, hydrochemical, as well as drilling, data are classified as attribute data using Microsoft Access, and joined with spatial information based on ArcView. The database management system and 3-D visualization interface to handle these data, also, developed using the script language of ArcView. We think the development of database and 3-D visualization system will improve the efficiency of data management, user-friendliness of data access, and accuracy of data analysis.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.410-415
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• 2003

Ground subsidence has occurred in the downtown of Muan-eup in Korea. Integrated geophysical survey, including two-dimensional resistivity, CSMT(Controlled source magnetotelluric), magnetic, borehole logging, GPR and resistivity tomography, has been conducted to investigate the cause of subsidence and ground conditions. Since the target area is in the city downtown, there were no spaces for surface geophysical methods. To get regional geology and to facilitate the detailed geophysical interpretation in the survey area, two-dimensional resistivity, CSMT and magnetic surveys have been applied in the outer region of the downtown. From these results, we could accurately define the Gwangju fault system and estimate the geologic conditions in the downtown. For the detailed survey of the downtown area, resistivity tomography and borehole logging data have been acquired using a few tens of densely located boreholes. Among these survey results, borehole logging data provided the guide to classification of the rock type and we could define the geologic boundary of granite and limestone formations. From the resistivity tomograms of 42 sections, which are densely located enough to be interpreted in a three-dimensional manner, we could delineate the possible weak zones or cavities in the limestone formations. In particular, resistivity tomograms in the subsided area showed the real image of ground subsidence. The map of hazardous zone has been derived from the joint interpretation of these survey results and we could provide the possible reinforcement strategy in this area.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.81-87
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• 2009

This study aims to evaluate how efficiently time-worn building could be managed by using GPS-based video-logging systems. The digitally georeferencing video data taken by a hand-hold GPS-based video-logging system allows quick retrieval and effective management for the complicate and various superannuated building in urban area. The results of the study are as follows. Georeferencing data are possible to trace observed positions by using GPS linked with video and to provide building crack information anytime that could be used to inspect and analyze the safety hazard diagnosis of buildings. Building crack information were measured by the proposed method that is merged with feature tracking and image mosaic of sequenced images. From the study, it reveals that the georeferencing video technique provides more realistic and reliable information in safety diagnosis and it can also be used as the essential and modern tool in urban building management.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.112-117
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• 2005

Geophysical logging is routinely undertaken as part of most coal mine exploration programs. Currently, the main application for the logs is to determine coal seam depth and to qualitatively estimate coal quality, lithology, and rock strength. However, further information can be obtained, if quantitative log interpretation is made. To assist in the uptake of quantitative interpretation, we discuss log responses in terms of the mineralogy of the clastic sedimentary rocks frequently found in the Australian black coal mining areas of the Sydney and Bowen Basins. We find that the log responses can be tied to the mineralogy with reasonable confidence. Ambiguities in the interpretation will be better resolved if a full suite of logs is run. A method for checking for internal consistency, by comparing calculated and observed velocities, is also described. A key driver for quantitative interpretation is geotechnical characterisation. We propose a classification system for clastic rocks that takes into consideration physical rock properties that can be inferred from geophysical logs.

• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.350-360
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• 2008

Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity is widely used in determination of rock quality in support pattern design of road and railway tunnel construction sites. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test in laboratory, such as P wave velocity, Young's modulus, uniaxial compressive strength (UCS) and electrical resistivity. We correlate each test results and we found out that electrical resistivity has highly related to P wave velocity, Young's modulus and UCS. Next, we accomplished electrical resistivity survey in field site and carried out electrical resistivity logging at in-situ area. We also performed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to RMR data. We found out that electrical resistivity logging data are highly correlate to RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RMR.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.118-127
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• 2010

Resistivity logging instruments are designed to measure the electrical resistivity of a formation, and this can be directly interpreted to provide a water-saturation profile. However, resistivity logs are sensitive to borehole and shoulder-bed effects, which often result in misinterpretation of the results. These effects are emphasised more in the presence of tool eccentricity. For precise interpretation of short- and long-normal logging measurements in the presence of tool eccentricity, we simulate and analyse eccentricity effects by combining the use of a Fourier series expansion in a new system of coordinates with a 2D goal-oriented high-order self-adaptive hp finite-element refinement strategy, where h denotes the element size and p the polynomial order of approximation within each element. The algorithm automatically performs local mesh refinement to construct an optimal grid for the problem under consideration. In addition, the proper combination of h and p refinements produces highly accurate simulations even in the presence of high electrical resistivity contrasts. Numerical results demonstrate that our algorithm provides highly accurate and reliable simulation results. Eccentricity effects are more noticeable when the borehole is large or resistive, or when the formation is highly conductive.

• Tunnel and Underground Space
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• v.12 no.3
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• pp.179-188
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• 2002

This study is to understand the effect of the vibration and the stress changes due to the excavation of 2 arch parts of a tunnel, which is a Gyungbu Express Railway tunnel, on the tunnel itself and adjacent slopes in advance, and to analyze the stability. For the estimation of ground conditions, borehole tests, borehole camera logging and seismic logging were performed. Ground properties at a specific location were determined as input constants by performing 2 dimensional analyses with possible ranges of uncertain ground properties. Static and pseudo-static (due to blasting vibration) factors of safety were calculated. The behavior of the tunnel and its vicinity due to the tunnel excavation were predicted by 3 dimensional analyses. It was also tested whether the support system was proper.

• Journal of Forest and Environmental Science
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• v.33 no.4
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• pp.281-294
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• 2017

Tropical forests constitute almost half of the global forest cover, account for 35% of the global net primary productivity and thereby have potential to contribute substantially to sequester atmospheric $CO_2$ and offset climate change impact. However, deforestation and degradation lead by unsustainable management of tropical forests contribute to the unprecedented species losses and limit ecosystem services including carbon sequestration. Sustainable forest management (SFM) in the tropics may tackle and rectify such deleterious impacts of anthropogenic disturbances and climatic changes. However, the existing dilemma on the definition of SFM and lack of understanding of how tropical forest sustainability can be achieved lead to increasing debate on whether climate change mitigation initiatives would be successful. We reviewed the available literature with a view to clarify the concept of sustainability and provide with a framework towards the sustainability of tropical forests for enhanced carbon stock and climate change mitigation. We argue that along with securing forest tenure and thereby reducing deforestation, application of reduced impact logging (RIL) and appropriate silvicultural system can enhance tropical forest carbon stock and help mitigate climate change.

• The Journal of Engineering Geology
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• v.24 no.3
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• pp.423-429
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• 2014

Development of a reservoir pressure core sampler (PCS) with a built-in data logging system (DLS) for recording real-time temperature and pressure observations is critical in domestic hydrocarbon production to accurately measure and monitor reserves of shale gas, coalbed methane, and gas-hydrate. Another purpose of this new technology is to minimize the loss of gas from the core as the drill core is collected. This is accomplished by maintaining the pressure of the sample from the moment the drill core is obtained at depth, thus allowing an accurate analysis of shale gas, coalbed methane gas, and gashydrate within the core. Currently, the United States and European countries have monopolized the development and marketability of PCS technologies. We are thus developing a reservoir PCS by analyzing the operating principle and mechanisms of the existing PCS, and by conducting tests on the existing PCS. We further aim to develop a PCS with a maximum operating pressure of 100 bar, a maximum operating temperature of $-20^{\circ}C$ to $40^{\circ}C$, and a pressure loss rate of 10%.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.294-298
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• 1993

The relationship between pH and the activity of ferrous iron in the reduced soil under water-logging was investigated theoretically and experimentally. The results of this study revealed, contrary to hitherto assumed, that the $pH-Fe^{+{+}}$ relationship in the commonly occurring rice soils under reduced condition is close to that in $FeCO_3-CO_2-H_2O$ system, being remote from that in $Fe_3(OH)_8-H_2O$ system and $Fe(OH)_2-H_2O$ system. This indicates that the activity of ferrous iron in the reduced rice soils under water-logging is likely to be governed by $FeCO_3$, neither by $Fe_3(OH)_8$, nor by $Fe(OH)_2$.