• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.190-207
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• 2015

In the combustion engineering, to decrease pollution and increase production efficiency, and to optimally keep solid burning material amount constant in a burner online, it needs a smart method to detect the amount variation of the burning materials in a high temperature environment. This paper presents an online machine vision system for automatically measuring and detecting the burning material amount inside a burner or a boiler. In the camera-protecting box of the system, a sub-system for cooling is constructed by using the cooling water circulation techqique. In addition, the key and intelligent step in the system is to detect the pile profile of the variable burning material, and the algorithm for the pile profile tracing was studied based on the combination of the gey level (color) discontinuity and similarity based image segmentation methods, the discontinuity based sub-algorithm is made on the quaternion convolution, and the similarity based sub-algorithm is designed according to the region growing with multi-scale clustering. The results of the two sub-algoritms are fused to delineate the final pile profile, and the algorithm has been tested and applied in different industrial burners and boilers. The experiements show that the proposed algorithm works satisfactorily.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.98-106
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• 2003

To construct pile-supported wharf structures that must support heavy horizontal loads, both vertical piles and batter piles are used. Batter piles are used to secure the bearing capacity against the horizontal loads. However, past case histories have shown that the heads of batter piles are vulnerable because these heads are subjected to excessive axial loads during earthquakes. Therefore, the aseismatic reinforcement method must be developed to prevent batter pile heads from breaking due to excessive seismic loads. Two different connecting methods of either inserting rubber or ball-bearing between batter pile head and upper plate were proposed to improve the aseismatic efficiency. Three large-scale pile head models(rubber type model, ball-bearing type model, and fixed type model) were manufactured and horizontal loading tests were peformed for these models. The results showed that the force-displacement relationship of the fixed type model was linear, but that of the rubber type model and the ball-bearing type model was bilinear. The increase in the horizontal displacement led to the increase in the horizontal stiffness of the rubber type models and the decrease in that of the ball-bearing type model. Compared with the values for fixed type model, the damping ratios of the rubber type model and the ball-bearing type model increased about 33~185％ and 263~269％, respectively.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.21-32
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• 2022

Steel pile foundations are widely used for offshore constructions due to their high bearing capacity and efficiency. Typically, offshore structures that have reached the end of their design life are required to be demolished. However, pile foundations are often left on site due to technical and economic limitations. The pile left on the site not only pollutes the environment, but can also cause obstacles for the construction of new structures. Therefore, research is required to completely eliminate these foundations at the site. In this study, a new type of double-wall pile foundation that can drastically reduce the pull-out load was conceptually proposed, and a series of model tests were performed to validate the performance of the double-wall pile foundation. The installation and extraction of the double-wall pile were simulated in dry sand in the model test, and the measured up-lift load was compared to that of the conventional pile. According to the result, the maximum up-lift load induced by the decommissioning of the double-wall pile was reduced by 45% when compared to the traditional pile in dense sand. This study verified the mechanism for reducing the up-lift load of the double-wall foundation and confirmed the possibility of completely decommissioning a pile that has reached the end of its nominal service life.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.6 no.2
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• pp.9-14
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• 2010

The ground source heat pump system is increasingly being considered as an alternative to traditional heating and cooling systems to reduce the emission of ground house gases. In this paper, A series of numerical analysis for energy piles has been performed focusing on heat transfer efficiency, performance and thermal stress. Results of numerical analyses for the W-shape type shows more efficient heat exchange transfer than the coil type. From results of the thermo-mechanical analysis, it is shown that the concentration of thermal stress occurs around the circulating pipe and the interfaces between different materials. The largest deformation caused by thermal stress is observed in the energy pile.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.21-35
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• 2016

It is a current trend that the concrete track is applied for high speed railway. In the case of the railway embankment constructed on soft ground, the damage to concrete track which is sensitive to settlement such as distortion and deflection could be caused by very small amount of long term settlement. Pile Supported Embankment method can be considered as the effective method to control the residual settlement of the railway embankment on soft ground. The Geosynthetics is used inside of the embankment to maximize the arching effect transmitting the load of the embankment to the top of the piles. But, PHC piles that are generally used for bridge structures are also applied as the pile supporting the load of embankment concentrated by the effect of the Geosynthetics. That is very low efficiency in respect of pile material. So, in this study, the cast in place concrete pile was selected as the most suitable pile type for supporting the embankment by a case study and the optimum mixing condition of concrete using a by-product of industry was induced by performing the mixing designs and the compressive strength designs. And it is shown that the cast in place pile with the optimum mixing condition using the by-product of industry is 2.8 times more efficient than the PHC pile for the purpose of Pile Supported Embankment by the finite element analysis method.

• Geotechnical Engineering
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• v.7 no.1
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• pp.41-52
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• 1991

A study of the effects of dynamic pile-soil-structure interactions on the response of super- structures, supported by group piles, are presented in this paper. The dynamic impedance functions of single pile generated by soil-pile interactions are obtained and compared among others using the methods proposed by Novak, Gazetas, and Kuhlemeyer, and using the equivalent cantilever method. Group pile effects are also considered by the following approaches : neglecting interaction effects : group efficiency ratio concept : static interaction approach . and dynamic interaction approach. The responses of a nuclear containment structure are obtained by using the elastic half-space analysis, based on the impedance functions mentioned above. Main conclusions drawn from this study are as follows : 1. The numerical results of the impedance functions calculated by each method were quite different : the Novak's was the smallest, and the Kuhlemeyer's the highest. Considering group effects, similar values in each approach were obtained for the stiffness : the difference was very big for the damping. 2. The top displacement of the structure was reduced by 20% or more by pile installations. However, the base shear force, the base moment, and the resonance frequency were increased by more than two times due to stiffening effect of the ground by pile installations. 3. Whether frequency dependant impedence functions or frequency independant functions were used, the responses of the structure were not so much affected by the choice of the impedance functions. 4. The reduction effect of the top displacement increased with the increase of the maximum ground acceleration.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.29-30
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• 2009

In this study, analyzing loads transferred to the piles, both easily constructed and mechanically improved pile head design method for the PHC pile is presented. To compare with mechanical capacity of the existing and proposed method, tensile, compression, moment, and shear tests are performed with 11 pieces of full-scaled blocks. As a result, mechanical capacities of the proposed method is superior to those of existing one in all aspects and work efficiency as well.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.194-198
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• 2008

The necessities of development of foundation having minimized occupying area and construction time are required for overpass in the downtown area by which bimodal tram will pass a crossway. We are studying a single column drilled pier foundation which is continuous from pier to pile foundation. Due to the increased resisting moment by reinforced steel which is ranged from the upper part of pile to lower part of column above ground, it can be possible to make a smaller pile-section and lessen the bar reinforcing. And for the excavation work is possible with smaller equipment, this foundation has a improved constructability and economical efficiency. This foundation needs smaller amount of concrete and has a small self-weight. It has an effect on improving resistance against earthquake due to improved ductility in addition to improved rigidity by interaction between concrete and steel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6C
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• pp.231-239
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• 2010

This paper presents the thermal conduction analysis (using ABAQUS ver 6.10 and FLUENT ver 6.3.26) of geothermal energy for PHC, steel and copper energy piles by considering subsurface environment, thermal efficiency of grouting materials, and fluid velocity of circulating fluid. Results show that higher thermal efficiency for copper pile is observed followed by steel and PHC piles depending on the grouting materials and subsurface condition. The fluid velocity of 0.6m/s presents most efficient outflow temperature (275.4K) and heat exchange rate (103.1W/m) for the case of PHC pile during 8 hours operation. Analysis of operation schedule concludes that 16 hours of stand-by allows charging geothermal energy following 8 hours operation in winter season is most appropriate with 0.1K of temperature difference from the steady-state condition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.361-375
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• 2015

An energy pile is one of the novel ground heat exchangers (GHEX's) that is a economical alternative to the conventional closed-loop vertical GHEX. The combined system of both a structural foundation and a GHEX contains a heat exchange pipe inside the pile foundation and allows a working fluid circulating through the pipe, inducing heat exchange with the ground formation. In this paper, a group of energy piles equipped with parallel U-type (5, 8 and 10 pairs) heat exchange pipes was constructed in a test-bed by fabricating in large-diameter cast-in-place concrete piles. In addition, a closed-loop vertical GHEX with 30m depth was constructed nearby to conduct in-situ thermal response tests (TRTs) and to compare with the thermal performance of the cast-in-place energy piles. A series of thermal performance tests was carried out with application of an artificial cooling and heating load to evaluate the heat exchange rate of energy piles. The applicability of cast-in-place energy piles was evaluated by comparing the relative heat exchange efficiency and heat exchange rate with preceding studies. Finally, it is concluded that the cast-in-place energy piles constructed in the test-bed demonstrate effective and stable thermal performance compared with the other types of GHEX.