• Journal of the Korean Association of Geographic Information Studies
• /
• v.22 no.2
• /
• pp.97-106
• /
• 2019

Today, many smart sensor's measurement instruments are used to check the safety situation of various medium and large bridge structures that should be maintained in the construction facilities, but most of them use the method of measuring and confirming the displacement behavior of the bridge at regular intervals. In order to continuously check the safety situation, various measuring instruments are used, but most of them are not able to measure and measure the displacement and behavior of main construction structures at regular intervals. In this study, GNSS and environment smart sensors and drone's image data are transmitted to wireless network so that risk of many bridge's structures can be detected beforehand. As a result, by diagnosing the fine displacement of the bridge in real time and its condition, reinforcement, repair and disaster prevention measures for the structural parts of the bridges, which are expected to be dangerous, and various disasters and accidents can be prevented, and disaster can be prevented could suggest a new alternative.

• Journal of the Korean Geophysical Society
• /
• v.6 no.3
• /
• pp.189-207
• /
• 2003

The purpose of this paper is to analyze the behavior and to study the safety evaluation of the Unmun Dam located in Cheongdo-Gun of GyeongBuk Province, Korea. For this purpose, soil analyses including boring data, geophysical surveys and monitoring the buried geotechnical gauges, such as pore-pressure gauge, earth-pressure gauge, displacement gauge, multi-layer settlement gauge, leakage flow-meter, were conducted. In addition to these data, numerical analyses of behavior of dam were performed to predict and to compare the data which were obtained from the above methods. Since many defects, such as gravel and weathered rock blocks in the dam core, and lots of amounts of leakage, by boring analyses were found, reinforcement by compaction grouting system (CGS) has been conducted in some range of dam. Some geotechnical gauge data were also used to confirm the effects of reinforcement. Analyses of monitoring the data of geotechnical gauges buried in the dam, such as pore-pressure gauge, earth-pressure gauge, displacement gauge, multi-layer settlement gauge, and leakage flow-meter shows the load transfer of dam and the possibility of hydraulic fracturing. As a conclusion, some problems in the dam found. Especially, the dam near spillway shows the high possibility of leakage. It should be pointed out that only the left side of he dam has not a leakage problem. As a whole, the dam has problems of weakness, because of unsatisfactory construction. It is strongly recommended that highly intensive monitoring is required.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.10
• /
• pp.93-100
• /
• 2006

The lateral soil movement in soft grounds undergoing improvement with application of vertical drains is analyzed on the basis of monitoring data at three fields, in which fifty six monitoring sites are located. Based on the investigations, the criterions are suggested to predict the lateral soil movement. In order to predict the lateral soil movement in the improved soft grounds by using the dimensionless parameter R suggested by Marche & Chapuis (1974), it is desirable that the maximum lateral displacement in the soft ground below the toe of embankment should be applied to calculate R instead of the lateral displacement at the toe of embankment. The lateral soil movement may increase rapidly, if the safety factor of slope is less than 1.4 in case of high ratio of H/B (Thickness of soft ground/Embankment width) such as 1.15 or is less than 1.2 in case of low ratio of H/B such as 0.05. Also, the graph suggested by Tschebotarioff (1973), which illustrates the relationship between the maximum height of embankments and the undrained shear strength of soft grounds, can be applied to the evaluation for the possibility of the lateral soil movement due to embankments on soft grounds.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.7
• /
• pp.569-576
• /
• 2014

Sensor node means a device to include sensor, amplifier, and data acquisition (DAQ) equipment. The sensor converts physical signals to electric signals and weak signals from the sensor can be amplified through the amplifier. DAQ equipment converts analog signal to digital signal and collects converted digital signal. Since the sensor node is sensitive to the environment so that selection of mounting position and fixture design of sensor are applied differently depending on the characteristics of a target. This study is about designing and manufacturing sensor node to be used in a machine tool. The environment of machine tool is very severe due to noise, temperature fluctuation, and dust, etc. Hence, the sensor and amplifier must be designed and manufactured by considering the environmental issues. The designed and manufactured sensor node was tested for the reliability and effectiveness of the developed sensor nodes in the study.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.2
• /
• pp.188-196
• /
• 2003

Liquid-assisted cleaning technology utilizing a nanosecond laser pulse is effective for removing submicron particulates from a variety of solid substrates. In the technique, saturated vapor is condensed on a solid surface to form a thin liquid film and the film is evaporated explosively by laser heating. The present work studies the role of liquid-film evaporation in the cleaning process. First, optical interferometry is employed for in-situ monitoring the displacement of the laser-irradiated sample in the cleaning process. The experiments are performed for estimating the recoil force exerted on the target with and without liquid deposition. Secondly, time-resolved visualization and optical reflectance probing are also conducted for monitoring the phase-change kinetics and plume dynamics in vaporization of thin liquid layers. Discussions are made on the effect of liquid-film thickness and dynamics of plume and acoustic wave. The results confirm that cleaning force is generated when the bubble nuclei initially grow in the strongly superheated liquid.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2006.06a
• /
• pp.277-280
• /
• 2006

Many industrial fields were constructed on the reclaimed land which was used to be a tidal land. Because the industrial fields stand on weak basement, they are likely to be influenced by surface subsidence. Therefore, the surface subsidence monitoring is required for civil protection. In this study, a novel method to monitor land displacement, PSInSAR technique, was applied to monitor the land subsidence of Incheon Port, which happened a decade ago. Although the land was reclaimed more than 20 years ago, quite a bit of deformation was observed during six years. The maximum subsidence rate reached to 30 mm/year. JERS-1 data was exploited in this study.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.8
• /
• pp.167-180
• /
• 2004

In this study finite element analysis using hyperbolic model was performed to predict the characteristics of stress-strain behaviour on concrete face earth dam (CFED : a tentative name) raised with coarse-grained materials corresponding to the face slab bedding zone of concrete face rockfill dam (CFRD). The results of finite element analysis were compared with field monitoring data, and the comparison showed a good agreement. And, the analysis results including locus of maximum displacement, maximum stress, stress concentration, and irregular load transfer would be used to devise rational field monitoring schemes for construction management and quality control during construction of CFED.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.706-711
• /
• 2001

This paper represents a relaxation matching algorithm based on global structure constraint satisfaction. Relaxation matching algorithm is a conventional approach to the matching problem. However, we confronted some problems such as null-matching and multi-matching problems by just using the relaxation matching technique. In order to solve the problems, in this paper, the matching problem is regarded as constraint satisfaction problem, and a relaxation matching algorithm is proposed based on global structure constraint satisfaction. The proposed algorithm is applied a landslide picture to show the effectiveness. When the algorithm is processed at landslide inspecting and monitoring system, motion parameters such as displacement area and its direction are computed. Once movement is recognized, displacements are estimated graphically with statistical amount in the image plane. Simulation has been done to prove the proposed algorithm by using time-sequence image of landslide inspection and monitoring system.

• Spatial Information Research
• /
• v.17 no.3
• /
• pp.301-307
• /
• 2009

Recently, the various studies has been focused on evaluating the damage and stability of long span bridge through measuring and monitoring to ensure the stability and usability. But, even if various studies are performed, it is hard to predict and evaluate the real motion of structure. The aim of this study is check the application of GPS to the motion monitoring of long span bridge by comparing data acquired form RTK-GPS and laser displacement meter.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.5
• /
• pp.9-13
• /
• 2009

Modal parameters including resonant frequencies and mode shapes are heavily utililized in most damage identification throries for structural health monitoring. However, extracting modal parameters from dynamic responses needs postprocessing which inevitably involves errors in curve-fitting resonants as well as transforming the domain of responses. In this paper, the applicability of a damage identification method based on free vibration responses to the in-sevice responses is experimentally verified. The experiment is performed via applying periodic and nonperiodic moving loads to a simply supported beam and displacement responses are measured. The moving load is simulated using steel balls and a downhill device. The damage identification results show that the in-service response may be applicable to identifying damage in the beam.