• The Journal of Engineering Geology
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• v.27 no.3
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• pp.217-231
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• 2017

The subsidence of ground in urban area can be caused by the occurrence of the cavity and the change in ground volumetric water content. The objective of this study is the detection of abnormal area of ground in urban area where the cavity or the change in ground volumetric water content is occurred by the ground penetrating radar signal. GPR survey is carried out on the test bed with a circular buried object. From the GPR survey, the signals filtered by the bandpass filtering are measured, and the methods consisting of gain function, time zero, background removal, deconvolution and display gain are applied to the filtered signals. As a result of application of the signal processing methods, the polarity of signal corresponds with the relation of electrical impedance of the cavity and the ground in test bed. In addition, the relative permittivity calculated by GPR signal is compared with that of predicted by volumetric water content of the test bed. The relative permittivities obtained from two different methods show similar values. Therefore, the abnormal area where the change in ground volumetric water content is occurred can be detected from the results of the GPR survey in case the depth of underground utilities is known. Signal processing methods and estimation of relative permittivity performed in this study may be effectively used to detect the abnormal area of ground in urban area.

• Composites Research
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• v.26 no.4
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• pp.235-244
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• 2013

A volume integral equation method (VIEM) is introduced for the solution of elastostatic problems in an unbounded isotropic elastic solid containing multiple isotropic elliptical fibers of arbitrary orientation subject to uniform stress at infinity. The fibers are assumed to be long parallel elliptical cylinders composed of isotropic elastic material perfectly bonded to the isotropic matrix. The solid is assumed to be under plane strain on the plane normal to the cylinders. A detailed analysis of the stress field at the matrix-fiber interface for square and hexagonal packing of the fibers is carried out for different values of the number, orientation angles and concentration of the elliptical fibers. The accuracy and efficiency of the method are examined through comparison with results obtained from analytical and finite element methods.

• Fire Science and Engineering
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• v.31 no.5
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• pp.19-27
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• 2017

The effects of changes in area and location of fire source, fire growth rate, and volume of compartment on the major fire characteristics, including heat release rate, in closed compartment fires were examined. To this end, a fire simulation using Fire Dynamics Simulator (FDS) was performed for ISO 9705 room with a closed opening. As main result, it was found that the changes in the area and location of fire source did not significantly affect the thermal and chemical characteristics inside the compartment, such as maximum heat release rate, total heat release, maximum temperature at upper layeras well as species concentrations. However, increasinthe fire growth rate and volume of compartment resulted in increase of the maximum heat release rate and total heat release, decrease in the limiting oxygen concentration and increase in the maximum CO concentration. Finally, a methodology for the application of fire growth curves to closed compartment fires was proposed by deriving the correlation of the maximum heat release rate expressed as a function of the fire growth rate and the volume ratio of compartment based on the ISO 9705 room.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.49-55
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• 2016

Field measurement units and a system were constructed and installed in a waste-dump slope at the Imgi mine to investigate and analyze the variations in the unsaturated characteristics of the soil. The field instrumentation system was composed of a data acquisition system (DAS), a solar system, and measuring sensors. The rainfall, matric suction, and volumetric water contents were continuously measured from the units in the instrumented site. The variations in matric suction and volumetric water content were primarily affected by the rainfall intensity. At the surface of the slope, the largest increase and decrease in the changes in matric suction and volumetric water content were observed during the wetting and drying processes, respectively. Also, the matric suction and volumetric water content were 5-35 kPa and 0.12-0.24, respectively. However, the ground water level was not suddenly increased just after rainfall but gradually increased after 2 or 3 days later.

• The Journal of Korean Society for Radiation Therapy
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• v.20 no.2
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• pp.83-89
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• 2008

Purpose: The checking method of target and normal structure are used by MVCBCT, KVCBCT, CT On-rail System, Ultrasound in H&N cancer patient. In case of MVCT, the utilization of bone structure is valuable to check around tissue. But the utilization of soft tissue is not enough. The point of this paper is dose variation in movable parotid and changeable volume of H&N cancer patient of CT On-rail System. Materials and Methods: The object of H&N cancer patient is 5 in this hospital. The selected patient are scanned ARTISTE CT Vision (CT On-ral System) a triweekly. After CT scanning, tranfered coordinates are obtained by movable of parotid gland comparison with planning image. Checking for the changeable volume of parotid gland. A Obtained CT image are tranfered to the RTP System. So dose variation are checked by following changed volume. Results: The changes of target coordinate by the parotid gland movement are X: -0.4~0.4 cm, Y: -0.4~0.3 cm, Z: -0.3~0.3 cm. the volume of GTV is decreased to about 7.11%/week and then both parotid gland volume are shrinked about 4.81%/week (Lt), 2.91%/week (Rt). At the same time, each parotid gland are diminished in radiation dose as 3.66%/week (Lt), 2.01%/week. Conclusion: Images from CT on the rail System which are able to aquire the better quality images of soft tissue in Target area than MVCBCT. After replanning and dose redistribution by required images, It could gain not only the correction of the patient set-tup errors but exact dose distribution. Accordingly, the delivery of compensated dose, It makes that we could do Adaptive Targeting Radiotherapy and need Real Time Adaptive Targeting Radiotherapy by reduce beam delivary time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.881-889
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• 2010

A volume integral equation method (VIEM) is introduced for solving the elastostatic problems related to an unbounded isotropic elastic solid; this solid is subjected to remote uniaxial tension, and it contains multiple interacting isotropic inclusions. The method is applied to two-dimensional problems involving long parallel cylindrical inclusions. A detailed analysis of the stress field at the interface between the matrix and the central inclusion is carried out; square and hexagonal packing of the inclusions are considered. The effects of the number of isotropic inclusions and different fiber volume fractions on the stress field at the interface between the matrix and the central inclusion are also investigated in detail. The accuracy and efficiency of the method are clarified by comparing the results obtained by analytical and finite element methods. The VIEM is shown to be very accurate and effective for investigating the local stresses in composites containing isotropic fibers.

• Composites Research
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• v.31 no.4
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• pp.161-170
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• 2018

Cylindrical composite lattice structures are manufactured by filament winding process. The fiber volume fraction non-uniformity and resin rich layers that can occur in the manufacturing process affect the stiffness and strength of the structure. Through the cross-section examination of the hoop and helical ribs, which are major elements of the composite lattice structure, we observed the fiber volume fraction non-uniformity and resin rich layers. Based on the results of the cross-section examination, the stiffness of the ribs was analyzed through the experimental and theoretical approaches. The results show that the fiber volume fraction non-uniformity and resin rich layers have an obvious influence on the rib stiffness of composite lattice structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.59-71
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• 2012

A volume integral equation method (VIEM) is introduced for the solution of elastostatic problems in unbounded isotropic elastic solids containing multiple interacting isotropic or anisotropic diamond-shaped inclusions subject to remote uniaxial tension. The method is applied to two-dimensional problems involving long parallel diamond-shaped cylindrical inclusions. A detailed analysis of the stress field at the interface between the matrix and the central inclusion is carried out for square and hexagonal packing of the inclusions. The effects of the number of isotropic or anisotropic diamond-shaped inclusions and of the various fiber volume fractions for the circular inclusions circumscribing its respective diamond-shaped inclusion on the stress field at the interface between the matrix and the central inclusion are also investigated in detail. The accuracy and efficiency of the method are examined through comparison with results obtained using the finite element method.

• Journal of the Korean GEO-environmental Society
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• v.12 no.3
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• pp.63-67
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• 2011

Recently, the application of unsaturated-soil theory is concerned in practice. Most characteristics of unsaturated-soil is the relationship between volumetric water contents and matric suction. Usually the volume water contents is estimated by the relationship between gravity water contents and volume water contents because of the difficulty of measurement of volumetric water contents. In this case, the water exists in only void of soil, and the relationship between gravity water contents and volume water contents is calculated by only water in void, but in fact, the water exists in the particle of the soil. So the real volume water contents is different with calculated volume water contents derived by the relationship containing only void water. The object of this research is to revise the relationship between volume water contents and gravity water contents by using the absorptivity tests of the soil particle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3794-3801
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• 2010

This study evaluated the linear dimensional changes with the factor of time and thickness using of three commercially available tissue conditioners (Coe-Comport, Visco-Gel, Soft-Liner). The thickness of materials were changed (1.5mm, 3.0mm) and the percentage changes in dimension were measured at 1h(baseline), 12h, 24h, 3 days and 7days after specimen preparation. The obtained data were analyzed by ANOVA with the SAS/PC statistical package. From the results, large differences appear between the various tissue conditioners. The results suggested that the period recommended for forming functional impression would be 36h to 3days after insertion in the mouth. Depending on the type of tissue conditioner over time, as there were significant differences in the elastic change(p<0.05). Tissue conditioner of the 1.5mm, 3.0mm thickness were significantly different by the dimensional stability(p<0.05). Elastic deformation of the ideal itself, and resilient when compared only the look, Visco-Gel 3.0mm group, stability was the most stable volume. In addition, it is important to select tissue conditioners suitable for functional impression because of the wide range of dimensional stability among the materials.