• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.354-356
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• 2001

The demand of the power and gas energy have been rapidly increasing with the industralization, therefore, the area where buried pipelines run parallel with the adjacent power lines and cross them increases in Seoul as well as other cities. These situation cause AC interference from the power lines. However, there aren't any standards to preserve the pipelines from AC interference in Korea. We just use other country's criteria directly. Other developed countries have used the various AC interference mitigation methods such as lumped grounding. cancellation wires and gradient control wires etc.. This paper introduces the steel plate method which is using for AC interference mitigation method in Korea and investigates the effects of mitigation methods through case study by computer simulation.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3169-3171
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• 2000

Most metal structures such as gas pipelines. oil pipelines, hot water pipelines and power cables etc. are buried in underground. Normally. metal structures corrode in underground by the electrochemical reaction. Then, metal structures need to be protected against corrosion. Cathodic protection is one of useful methods to protect metal structures against corrosion. In this paper we do the design of anode shape using Boundary Element Method. So we analysis the current density of anode surface and the potential distribution in the electrolyte. Therefore we seek to maximize the anode life and the safety of metal structures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1131-1137
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• 2012

Subsea pipelines have been operated with buried depths of 1.2-4m underneath the seabed to prevent buoyancy and external impacts. Therefore, they have to show resistance to both the soil load and the hydrostatic pressure. In this study, the structural integrity of a subsea pipeline subjected to soil load and hydrostatic pressure was evaluated by using FE analyses. A parametric study showed that the internal pressure increased the plastic collapse depth by increasing the resistance to plastic collapse. The hoop stress increased with an increase in the buried depth for the same water depth; however, the hoop stress decreased with an increase in the water depth for the same buried depth.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.16-23
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• 2015

The industrialization and urbanization forced to increase the density of pipelines such as water supply, sewers, and gas pipelines. The materials used for the existing pipe lines are mostly composed of concretes and steels, but it is true that the development for more durable and efficient materials has been continued performed to produce long lasting pipe lines. Recently, underground pipes serve in diverse applications such as sewer lines, drain lines, water mains, gas lines, telephone and electrical conduits, culverts, oil lines, etc. In this paper, we present the result of investigation pertaining to the structural behavior of unplasticized polyvinyl chloride (PVC-U) flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, pipe stiffness, 4-point bending test, experimental and analytical studies are conducted. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is about 8% although there are significant variations in the mechanical properties of the pipe material. In addition, it was found by the 4-point bending test there is no problem in the connection between the pipes by coupler.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1326-1333
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• 2006

Purpose of this research is a development for the curve fitted equations that can improve practical calculation and work application when seismic performance has been evaluated and this work has been made a study of the dynamic response under various boundary conditions of buried pipelines to compare the dynamic behavior of concrete pipe and steel pipe, FRP pipe. This research have been developed curve fitted equations that can be improving efficiency and practicality. Using a nonlinear least square method, and after testing several different exponential equations, Proposed the curve fitted equations to give the best result and constant value by the propagation velocities. With these results, dynamic response analysis and seismic performance evaluation have been achieved on concrete pipe, steel pipe and FRP pipe that have a various boundary conditions. Degree of a polynomial expression and coefficient value by propagation velocity have been calculated when using the curve fitting equations.

• Journal of Ocean Engineering and Technology
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• v.34 no.3
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• pp.194-201
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• 2020

In this study, an optical-fiber sensor was used to measure loads that could act in an environment similar to the loading conditions that exist in an actual pipe. The structure and the installation method of the optical-fiber strain sensor were applied considering the actual large pipe and the buried pipe environment. Load tests were performed using a displacement sensor and sandbags to determine the deflection of the pipe according to the external load, and the linear measurement results were verified. Considering the conditions that could exist in the actual pipe, the test method was presented, and the strain of the buried pipe generated at this time was measured.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.83-88
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• 2017

We have examined the effect of values of subgrade reaction coefficient on the dynamic responses(displacement and strain responses) of the buried concrete pipeline of which the end boundary condition is the fixed ends. We have carried out the dynamic analysis of mode superposition method with representative values of coefficient of subgrade reaction applicable to the classified rock masses. We have found that the effect of subgrade reaction coefficient on the dynamic responses of the pipeline appears noticeable for the seismic waves having relatively high frequency and low apparent propagation velocity.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.41-47
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• 2006

This paper introduces stress monitoring system for buried gas pipeline in poor ground. During the six months of improvement construction of poor ground, maximum settlement of gas pipeline is about 40 cm. This value represents relative small compared to the initial settlement estimation of ground improvement construction plan, 90 cm. Also, this paper includes the result of finite element analysis of gas pipeline to confirm safety of pipelines in poor ground. The stress monitoring system for gas pipeline was developed to guarantee the safety of buried gas pipeline in poor ground. Eventually, the ground improvement workings are ended safely and it is proved that the pipeline has no safety problem.

• Corrosion Science and Technology
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• v.2 no.3
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• pp.161-163
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• 2003

With the development of Chinese petroleum and gas industry, about 20,000 km long-distance pipeline and 250,000 km gathering pipeline have been constructed in China. After operating for many years, most of the coatings on buried pipelines have aged so severe that the steel pipes are subject to corrosion environment underground. Focusing on the need of external coating for buried pipeline rehabilitation, a new type of coating has been developed. The development and application of the coatings has been introduced in this paper.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.328-337
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• 2005

This work reports results of our study on the dynamic responses of the buried pipelines both along the axial and the transverse directions under various boundary end conditions. We have considered three cases, i.e., the free ends, the fixed ends, and the fixed-free ends for the axial direction, and three more cases including the guided ends, the simply supported ends, and the supported-guided ends for the transverse direction. In order to investigate the effect of the boundary end conditions for the dynamic responses of the buried pipeline, we have devised a computer program to find the solutions of the formulae on the dynamic responses (displacements, axial strains, and bending strains) under the various boundary end conditions considered in this study. The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. The former is identified by a slight change in its behavior before the sinusoidal-shaped seismic wave travels along the whole length of the pipeline whereas the latter by the complete form of a sinusoidal wave when the wave travels throughout the pipeline. The transient response becomes insignificant as the wave speed increases. We have observed a resonance when the mode wavelength matches the wavelength of the seismic wave, where the mode number(k) of resonance for the axial direction is found to be $\overline{\omega}/{\pi}V+1/2$ for the fixed-free ends, $\overline{\omega}/{\pi}V+1$ for the free ends, and $\overline{\omega}/{\pi}V$ for the fixed ends, respectively. By adding 10 more modes to the mode number(k) of resonance, we were able to study all the dynamic responses of the buried pipeline for the axial direction. On the other hand, we have not been able to observe a resonance in the analysis for the transverse direction, because the dynamic responses are found to vanish after the seventh mode. From the results of the dynamic responses at the many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement and the strain and its position.