• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.2019-2029
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• 2001

Up to now a wide variety of researches on inpipe inspection robots have been introduced, but it still seems to be difficult to construct a robot providing mobility sufficient to navigate inside the complicated configuration of underground pipelines. This paper introduces a robot called MRINSPECT IV(Multifunctional Robotic Crawler for inpipe inSPECTion IV) for the inspection of urban gas pipelines with a nominal 4-inch inside diameter. The proposed robot can freely move along the basic configuration of pipelines such as along horizontal or vertical pipelines. Moreover it can travel along reducers, elbows, and steer in the branches by modulating the speeds of driving modules. Especially, its capability for steering in tile three-dimensional pipeline configuration has a competative edge over the other ones and provides excellent mobility in navigation. Its critical points in the design and construction are introduced and results of experiments are given.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.75-80
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• 2008

According to the Integrated Notice on City Gas Safety Management Standards, materials for bedding and foundation which are around the pipe should be sands or fine grade soil without large particle that is more than 19 mm size. However, sands are mostly used at gas pipeline construction sites and this causes a shortage of sands and an increase of construction costs. It even causes the disruption of natural environment. In order to improve the standards of backfill material, we have researched regulations in other countries and investigated the pipeline construction sites to survey the present state of backfilling. We also have studied what the bedding and foundation materials affect on buried gas pipelines. Lastly, we have suggested suitable materials for bedding and foundation besides sands. We are sure this paper help the government amend the Notice about backfill materials.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.33-43
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• 2016

Grinding, weld deposition, type A sleeve, type B sleeve, composite sleeve, hot tapping and clamp are used as the method to repair the buried pipelines in the United States, UK and Europe. In the event of defect to the pipeline, they have repaired the pipeline through the fitness-for-service assessments. In addition, they have guidelines for the possible repair methods to apply to each type of damage, which is occurred due to the 3rd party construction or corrosion. According to the KGS FS551, Safety Validation in Detail including ECDA(External Corrosion Direct Assessment) as one method of integrity management should be carried out for the old pipeline which supply natural gas as the middle pressure in Korea. Where a defect on the pipelines is found, on the result of Safety Validation in Detail, the pipelines should be repaired or replaced by new piping. However, there are no guidelines or regulations regarding the repair and reinforcement of pipeline, so that, cutting the damaged pipeline and replacing it as a segment of new pipe is the only way in Korea until now. We have suggested pipeline repair methods including type A, B sleeve, composite sleeve, after the survey of foreign repair method and standards including the method of United States and the United Kingdom, and after analysis of the results on pipeline repair test including type A, type B sleeve and composite sleeve.

• Proceedings of the KIEE Conference
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• 2005.11c
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• pp.53-55
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• 2005

Because of the continuous growth of energy consumption and also the tendency to site power lines and pipelines along the same route, the close proximity of power lines and buried metallic pipelines has become more and more frequent. The lightning strokes collected by an electric substation or power line tower might cause arcing through the soil to an adjacent gas pipeline. This paper gives the review of the breakdown mechanism and the standards of separation distance between lower and pipelines.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.131-147
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• 2015

In modern society, as to the underground urban infrastructure facilities(communication electricity water and sewage gas etc.) were contained many risks because of excavating. The exact position of underground facilities and the attribute information should be built in order to prevent accidents. As the result of analyzing the public surveying results from 2004 to 2009, it shows that low detecting rate of water pipeline which is only 52.4%, because the exploration of electromagnetic induction only detect metal pipeline and positioning survey only detect new pipeline before burying. Therefore development and verification of the correct and efficient exploration techniques are needed to improve the detecting rate. In this study, determined based on the location measurement results for the non-metal pipes and metal pipes before burial. It was compared with values that obtained through the ground penetrating radar and electromagnetic induction detecting. As a result, detecting rate of the concrete section showed a 100%, unpaved section showed a 94.7%, asphalt section showed 60%. So it confirmed the applicability of the ground penetrating radar at underground facilities detecting.

• Journal of the Korean Magnetics Society
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• v.15 no.6
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• pp.325-331
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• 2005

The magnetic Hut leakage (MFL) type nondestructive testing (NDT) method is widely used to detect corrosion and defects, mechanical deformation of the underground gas pipelines. The object pipeline is magnetically saturated by the magnetic system with permanent magnet and yokes. Because of the strong magnetic field enough to saturate the pipe, there could be distortion of the sensing signals because of the magnetization of the pipeline itself, To detect the defects precisely, the sensing signals are need to be compensated to eliminate the distortions coming from the media hysteresis. In this paper, the magnetizations of the pipeline in MFL type NDT are analyzed by Preisach model and 3D FEM. The distortions of the sensing signals are analyzed.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.651-656
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• 2014

Corrosion has a significant influence upon the reliability assessment and the maintenance planning of gas pipeline. Corrosion defects occurred on the underground pipeline can be obtained by conducting periodic in-line inspection (ILI). However, little study has been done for practical use of ILI data. This paper deals with remaining lifetime prediction of the gas pipeline in the presence of corrosion defects. Because a pipeline parameter includes uncertainty in its operation, a probabilistic approach is adopted in this paper. A pipeline fails when its operating pressure is larger than the pipe failure pressure. In order to estimate the failure probability, this paper uses First Order Reliability Method (FORM) which is popular in the field of structural engineering. A well-known Battelle code is chosen as the computational model for the pipe failure pressure. This paper develops a Matlab GUI for illustrating failure probability predictions Our result indicates that clustering of corrosion defects is helpful for improving a prediction accuracy and preventing an unnecessary maintenance.

• Journal of the Korean Magnetics Society
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• v.26 no.1
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• pp.24-30
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• 2016

MFL (Magnetic flux leakage) type nondestructive testing has been used for inspection of underground gas pipelines to find metal defects by detecting magnetic leakage signal. Because the underground gas pipeline is exposed by environment such as high pressure with great humidity, external defects are easily formed on the surface of pipelines and they are being grouped respectively. These adjacent defects cause the signal distortion of leakage flux so that it is hard to estimate the shape information of defects. In this paper, we performed to study of the signal distortion and compensating method for multiple defects in MFL type nondestructive testing system by using 3D FEM simulation. This paper proposes the basic algorithm of defect signal analysis on multiple defects on the surface of 30 inch diameter pipeline.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.311-316
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• 2010

Defects positioning of underground gas pipelines using MFL(magnetic flux leakage) inspection which is one of non-destructive evaluation techniques is proposed in this paper. MFL signals acquired from MFL PIG(pipeline inspection gauge) have nonlinearity and distortion caused by various external disturbances. SQI(self quotient image), a compensation technique for nonlinearity and distortion of MFL signal, is used to correct positioning of pipeline defects. Through the experiments using artificial defects carved in the KOGAS pipeline simulation facility, it is found that the performance of proposed defect detection is greatly improved compared to that of the conventional DCT(discrete cosine transform) coefficients based detection.

• Journal of the Korean Institute of Gas
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• v.23 no.1
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• pp.62-69
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• 2019

The high pressure underground pipelines of industrial states such as Ulsan, Yeosu consist with not only the pipelines for the utility support such as Raw material of petrochemical industry and steam, but also high pressure pipelines of toxic, flammable gas intricately like a web. Therefore, in this study, based on in-depth comparison analysis of industrial estate pipelines, and underground city gas pipelines' safety management status, excavation frequency, excavation depth, patrol period which are pipe damage impact factor by the other construction are analyzed. And, as a result, risk changes and correlations due to risk reduction strategy of the other construction are compared to be presented the safety inspection operation model for the high pressure underground pipelines of industrial estates.