• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.117-129
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• 2009

This paper studied the safety management network system of infrastructure which constructed smart sensors, closed-circuit television(CCTV) and monitoring system. This safety management of infrastructure applied to bridge, cut slop and tunnel, embankment etc. The system applied to technologies of standardization guidelines, data acquirement technologies, data analysis and judgment technologies, system integration setup technology, and IT technologies. It was constructed safety management network system of various infrastructure to improve efficient management and operation for many infrastructure. Integrated safety management network system of infrastructure consisted of the real-time structural health monitoring system of each infrastructure, integrated control center, measured data transmission using i of tet web-based, collecting data using sf ver, early alarm system which the dangerous event of infrastructure occurred. Integrated control center consisted of conference room, control room to manage and analysis the data, server room to present the measured data and to collect the raw data. Early alarm system proposed realization of warning and response within 5 minute or less through development of sensor-based progress report and propagation automation system using the media such as MMS, VMS, EMS, FMS, SMS and web services of report and propagation. Based on this, the most effective u-Infrastructure Safety Management System is expected to be stably established at a less cost, thus making people's life more comfortable. Information obtained from such systems could be useful for maintenance or structural safety evaluation of existing structures, rapid evaluation of conditions of damaged structures after an earthquake, estimation of residual life of structures, repair and retrofitting of structures, maintenance, management or rehabilitation of historical structures.

• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.13-25
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• 2012

Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.

• Journal of the Korean Geosynthetics Society
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• v.13 no.3
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• pp.1-10
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• 2014

Several types of methods such as resistivity survey, ground penetration radar, etc are used for detection of levee leakage and according to the river design guidelines detection of levee leakage is performed by measuring the hydraulic conductivity of levee soil. But, the former can not verify the leakage point and degree of saturation, the latter is an after treatment method. Movable sensor, which is a high-tech TDR system developed since 2000, can obtain directly the dielectric constant profile covering the whole depth of levee. In this study, laboratory and field model experiments were carried out using movable TDR sensor in order to evaluate the applicability as detection system of levee leakage, As the result, movable TDR system has proven to be 3 times more sensitive to water contents than dry unit weight, and the results conclude that the dielectric constant, water contents and density of the ground proved to have a correlation among them, and the dielectric constant is expected to be a basic data on detection of levee leakage.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.223-231
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• 2012

Many cut slopes are located near national highways, resulting in large annual damage to infrastructure from the collapse of cut slopes. Therefore, to effectively maintain cut slopes, high-risk slopes should be identified and monitored. In this paper, we evaluate the effectiveness of the management of cut slopes using the risk score calculated from cut-slope inventory data. The inventory survey, as a simple assessment of the characteristics of various slopes, was performed to collect basic data that could be obtained visually in the field for the management of cut slopes. This method is not a precise survey, and it was composed of the general status and characteristics of cut slopes, the inspector's assessment, and inventory data in order to estimate a risk score for each slope. In this paper, we calculated the risk score by investigating the present status of cut slopes adjacent to 10,461 national roads. In order to evaluate the effectiveness of using risk score data, we compared the score for stable slopes with those of failed cut slopes. Failed cut slopes occurred in sections with the highest risk score. The results show that risk score derived from the inventory survey of cut slopes are useful in the management of cut slopes with risk of failure and in monitoring large numbers of cut slopes.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.97-104
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• 1999

This case study has been prepared to provide the practical data about construction of temporary shoring facilities (i.e. braced sheet pile excavation) and to utilize the case study information effectively for design and construction of future facilities. This case study includes information such as 1) installing measurement devices to monitor the deformation of the sheet pile walls and the subsoil in the vicinity after establishing the criteria for the sheet pile deflection; 2) monitoring the actual movement of the temporary facility after setting up the survey control standard (due to the movement of the temporary facility) : 3) inspecting the suitability of the temporary facility construction: and 4) analyzing and studying the result of the tension test after installing ground anchors.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.145-152
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• 1999

In the applying of the reinforced soil method, it would be possible to obtain reinforcement effect more than before in terms of economic if high water content clayey soils could be used as embanking material. Futhermore it would be possible to expect the expansion of the applying field of reinforced soil method too. In this study, the authors describe the analysis results on the behavior of 5 meter high walls reinforced with nonwoven geotextile having the permeability and woven geotextile or geogrid having large tensile strength on the soil ground. The behavior of the walls were investigated for about 100 days after construction and the deformations of reinforcements, lateral soil pressures, vertical and horizontal displacements of the walls were examined by automatical measuring system. It was found that this kinds of reinforcing system might effectively improve the performance of the steep walls by virtue of the reciprocal action between soil and reinforcements, and it might be concluded that construction of the clayey reinforced soil walls with three kinds of geotextiles could be done successfully even on the comparative weak ground.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10c
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• pp.19-27
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• 2001

Early detection of premonitory symptom of slope movement ensures tremendous saving of lives and repair costs from catastrophic disaster. Therefore, it is essential to constantly monitor the performance and integrity of both reinforced and un-reinforced cut slopes. We developed a novel monitoring system by using tension wire sensors. It's advantages are highly sensitivity, simple installation, large displacement measurement, durability of system, capability of remote sensing. Real-time measurement of slope surface movement is shown graphically and it gives a warning when the monitored value exceeds a given threshold level so that any sign of abnormal slope movement can be easily perceived.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.215-222
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• 2000

The reinforced roadbed should have the ability to spread out the load intensity lower than the bearing capacity of the subgrade of track structure as well as to prevent the softening of roadbed by providing appropriate stiffness in the roadbed, thus fully supports the track structures. Full scale reinforced roadbeds with several different types of monotoring sensors was also constructed to evaluate the performance of each reinforced roadbed through the continuous monitoring while the train operation. In this study, Field tests such as PLT, SASW were also carried out at each reinforced roadbed. The results of the field and lab tests, installation and calibration of sensors, as well as construction condition of the reinforced roadbed are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.605-614
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• 2010

In this paper, the initial behavior of transmission tower was analyzed. This tower was firstly constructed by rock anchor foundation in domestic 154 kV transmission line and wireless real-time monitoring system was installed to obtain the measured data for analysis of the structure behavior. For this purpose, 16 strain gauges was installed in anchors of foundation and strain gauges, clinometers, anemoscope and settlement sensors was installed at superstructure. As the results, the main factor which influence the behavior of superstructure is wind velocity, wind direction, rainfall and temperature change. Especially, the uplift load at stub of transmission structure revealed about 35.4 percentages of design load. Hereafter the long term stability will be analyzed.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.302-305
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• 2005

In this study, settlement characteristics of 38 CFRD was investigated from monitoring data and the method to estimate the dam settlements considering valley shape during constructions was proposed. The construction modulus of dam was found to be dependent on void ratios and valley shape factor. The construction modulus varied with valley shape and decreased with increasing void ratio. Also, the modulus was increased when the shape coefficient was less than 4. The settlement investigation results showed that the total settlement was proportional to the value of the settlement coefficient multiplied by the shape coefficient divided by void ratio.