• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1278-1289
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• 2008

Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method (NATM). Successful design, construction and maintenance of NATM tunnel in urban area demands prediction, control and monitoring of surface settlement, gradient and ground displacement with high accuracy. Use of measured displacement for parameter determination has been researched over the years, and one geotechnical engineering principle has been formed as back analysis. In this paper, back analysis of a ground deformational behavior involving nonlinear behavior is discussed. It is of primary importance to make reliable prediction of deformational behavior for shallow tunnels in soft ground. However, predictions made often prove to be incorrect due to complexity of constitutive law and other relevant factors. Back analysis therefore becomes more important, for it may be used to interpret measured displacement to derive nonlinear material characteristics. The paper shows some example in which a deformational mechanism is studied in the light of inhomogeneous distrubution of Young's module, from which a logic is derived to identify two different types of nonlinear constitutive relationships.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.459-465
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• 2013

This paper presents a differential interferometry technique for soil moisture change detection by measuring surface-height variation. COSMO-SkyMed SAR images were used to verify the DInSAR(differential interferometric SAR) technique. The soil penetration depth changes according to soil moisture, that causes phase change of the received signal. The height of soil surface and its displacement can be detected by a radar interferometry technique using phase difference of two received signals. To retrieve displacement variation, one of three SAR images is used as a reference image. Reference image and other two images are processed by the differential interferometry technique in the same area. The soil moisture was measured for the test sites to verify the DInSAR technique. The penetration depth is calculated by using the in-situ measured soil moisture data and it is compared with the displacement values acquired by the DInSAR technique.

• Explosives and Blasting
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• v.38 no.2
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• pp.1-12
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• 2020

Digital Image Correlation is a well-established method for displacements, strains and shape measurements of engineering objects. Stereo-camera 3D Digital Image Correlation (3D-DIC) systems have been developed to match the specific requirements for measurements posed by material and mechanical industries. Although DIC method provides the capabilities of scaling a field-of-view(FOV), dimensions of Geotechnical structure objects in many cases are too big to be measured with DIC based on a single camera pair. It can be the most important issue with applying 3D DIC to the measurement of Geotechnical structures. In this paper, We were present stereo vision conditions in a 3D DIC system that can be measured for large FOV(30×20m) and high precisions(z-displacement 0.5mm) of the ground objects with Stereo-camera DIC systems.

• Composites Research
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• v.30 no.1
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• pp.15-20
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• 2017

In this study, LIPCA-S2 actuator with a piezoelectric single crystal layer and a carbon/epoxy layer was designed and evaluated to increase actuation performance of piezo-composite unimorph actuator. A curvature change model generated by the induced strain of a piezoelectric layer was used to predict the tip displacement of the piezo-composite unimorph cantilever. However, we found that there was big difference between the predicted and the measured tip displacement of LIPCA-S2 cantilever actuator when we used the previous linear prediction model. A new prediction model considering the change of piezoelectric strain coefficient and elastic modulus for the compression stress variation of the PMN-29PT single crystal layer was used and it was found that the difference between the predicted and the measured tip displacement reduced considerably.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.19 no.1
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• pp.49-54
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• 2013

Background: The purposed of this study is to examine the static and dynamic plantar foot pressure in chronic low back pain patients and normal adults. Methods: The subjects were divided into a group of 30 patients with chronic low back pain and a control group of 30 healthy persons. While static posture and dynamic posture at comfortable walking speeds, the low back pain group and the control group measured their plantar foot pressure and the trajectory of their center of pressure (COP) using the Matscan(R) system. Independent t-tests were measured to compare differences in plantar foot pressure characteristics between the left side and right side of the low back pain group and the control group. Results: In the comparison of differences in plantar foot pressure characteristics between the left side and right side of the low back pain group and the control group, the anteroposterior (AP) displacement of COP showed significant differences (p<.05). Although the low back pain group and the control group did not show any significant differences in leg length, weight distribution, mediolateral (ML) displacement of COP, static contract area, dynamic contract areas (p>.05), increases in the contract area values were shown in the hind foot in general. Conclusion: In this study, it was shown that patients with chronic low back pain were walking with short AP displacement of the COP as a compensatory action to avoid pain.

• Journal of the Korean Geosynthetics Society
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• v.13 no.3
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• pp.39-47
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• 2014

In this study, the full scale model tests were performed with track-roadbed system such as Ho-nam high speed railway. The measured data gives good similar a roadbed pressure with equivalent depth to the Odemark's theory. In the case of earth pressures have a under 50 kPa at upper-subgrade applying 330 kN static loading. Results of cyclic loading tests did not differ significantly from those of static loading test. The elastic displacement at HSB layer has a level of 1/100 compared to the 1 mm that it was evaluation criteria for speed up of High Speed Railway. Elastic displacement at subgrade layer was measured a level of 1/175. The dynamic characteristics of track-roadbed with loading frequency level were linearly increased under 35 Hz, while the wheel loading, displacement and acceleration of roadbed were decreased loading frequency above 35 Hz.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.18-28
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• 2007

Three diesel engines were fueled with BDF 20, a blend of 80% diesel fuel and 20% biodiesel fuel by volume, and run in excess of 200 h to evaluate their combustion characteristics and durability. The engines used for this study were a 4-cylinder 2476-cc displacement IDI diesel engine(Engine 1), a 4-cylinder l732-cc displacement IDI diesel engine(Engine 2), and a single cylinder 673-cc displacement DI diesel engine(Engine 3). Engine dynamometer testing was performed on each engine at regularly scheduled intervals to monitor the performance and exhaust emissions, which were sampled at 1h intervals for analysis, The peak combustion pressure with BDF 20 increased in Engines 1 and 3 over that measured when burning pure diesel fuel, but that in Engine 2 remained constant. Combustion parameters, such as the maximum combustion pressure and corresponding crank angle, did not change over the long-term dynamometer testing. The BSFC with BDF 20 in Engine 1 was less than that measured with pure diesel fuel. The amount of smoke produced with BDF 20 was less for all engines ; the greatest reduction was observed for Engine 3. The NOx emissions were lower in the IDI engines than the DI engine. The traditional trade-off between smoke and NOx emissions was maintained for BDF 20 fuel for Engines 1 and 3. There was not a big difference in the $CO_2\;and\;O_2$ emissions for BDF 20, as compared to pure diesel fuel, but more $CO_2$ was exhausted by Engine 1 than by Engines 2 or 3 and less $O_2$ was exhausted by Engine 1 than by Engines 2 or 3. The engine parts remained clean, except for some carbon attached to the area surrounding the nozzle hole of the DI diesel engine.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.187-196
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• 2016

We conducted three-dimensional finite element analysis to predict the presence of upcoming fault zones during tunneling. The analysis considered longitudinal displacements measured at tunnel face, and used 28 numerical models with various fault attitudes. The x-MR (moving range) control chart was used to analyze quantitatively the effects of faults distributed ahead of the tunnel face, given the occurrence of a longitudinal displacement. The numerical models with fault were classified as fault gouge, fault breccia, and fault damage zones. The width of fault cores was set to 1 m (fault gouge 0.5 m and fault breccia 0.5 m) and the width of fault damage zones was set to 2 m. The results, suggest that fault centers could be predicted at 2~26 m ahead of the tunnel face and that faults could be predicted earliest in the 45° dip model. In addition, faults could be predicted earliest when the angle between the direction of tunnel advance and the strike of the fault was smallest.

• Journal of the Korean GEO-environmental Society
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• v.13 no.8
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• pp.25-33
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• 2012

Although it is important to reflect the accurate information of the ground condition in the tunnel design, the analysis and design are conducted by limited information because it is very difficult to consider various geographies and geotechnical conditions. When the tunnel is under construction, examination of accurate safety and prediction of behavior are overcome the limits of predicting behavior by Artificial Neural Network in this study. First, construct the suitable structure after the data of field was made sure by the multi-layer back propagation, then apply with algorithm. Employ the result of measured data from database, and consider the influence factor of tunnel, like supporting pattern, RMR, Q, the types of rock, excavation length, excavation shape, excavation over, to carry out the reliable analysis through field applicability of Artificial Neural Network. After studying, using the ANN model to predict the shearing displacement, convergence displacement, underground displacement, Rock bolt output follow the excavation over of tunnel construction field, then determine the field applicability with ANN through field measured value and comparison analysis when tunnel is being constructed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.97-105
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• 2010

The displacements of steel deck bridge due to construction step are measured, and three dimensional analysis with full modeling is carried out to compare with the measured results. Three dimensional structural analyses considering construction step by large block construction method are accomplished with verified model. The conclusions are as follows. 1. Comparing the data of grid analysis with the result of 3D full modeling in steel deck bridge, the design method using grid analysis has a limit for describing the displacements of curved bridge. The analysis of 3D full modeling has been proved as more accurate method. The differentiation of results in two methods is about 10%~20%. 2. It is verified that the maximum displacement of during construction is 1.7 times larger than the displacement of final construction. 3. The bridge behavior considering the construction step is somewhat different from that of final stage in whole structure and the displacement and stress during construction is larger than that of final construction. Therefore, it needs the reasonable structural design considering the construction step to get economical efficiency and a high competitive construction.