• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.41-47
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• 2006

When an underground pipeline runs parallel with DC electric railways, it suffers from electrolytic corrosion caused by the stray current leaked from the railway negative returns, i.e., the rails. Perforation due to the electrolytic corrosion may bring about large-scale accidents even under cathodically protected condition. Traditionally, drainage bonding methods have been widely used as a mitigation method for stray current interference. In particular, the increased adoption of forced drainage method to gas pipelines makes the interference much more sophisticated. In this paper, we analyze the electric interference between pipelines and railways from the results of field investigation carried out in Seoul and Busan.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.62-71
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• 2018

According to own investigation conducted by Korea Gas Safety Corporation Gas Safety Research Institute in 2017, the length of underground pipes in domestic high-pressure gas pipelines is approximately 770km, of which 84% is buried in Ulsan and Yeosu industrial complexes. In particular, 56% of underground pipelines have been in operation for more than 20 years. This suggests urgent management of buried high pressure gas pipelines. PHMSA in US and EGIG in Europe, major causes of accidents in buried gas pipelines are reported as third party damage, external corrosion and loss of pipe wall thickness. Therefore, it is important to evaluate whether the defects affect the remaining life of the pipe when defects occur in the pipe. DNV and ASME have evaluated the residual strength of pipelines through the hydraulic rupture test using pipe specimens with artifact flaws. Once the operating pressure is known through the residual strength of the pipe, the wall thickness at the point at which the pipe ruptures is calculated. If we know the accurate rate of corrosion growth, we can predict the remaining life of pipe. In the study, we carried out experiments with A53 Grade.B and A106 Grade.B, which account for 80% of domestic buried pipes. In order to modify the existing model equation, specimens with a defect depth of 80% to 90% was tested, and a formula expressing the relationship between defect and residual strength was made.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.9-16
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• 2016

Buried pipe system is subject to leak or rupture due to internal and external defects with age. Especially, if the pipeline is designed for pressurized gas, the leak can wreak a devastating on its surrounding area. The current method of setting up underground gas pipeline is based on OGP criteria of applying one tenth of the inner pipe pressure. The criteria is applied irrespective of their burial depth or pipe's properties. At times, even the whole safety measures are totally ignored. Considering the magnitude of possible damage from a gas leakage, a precise analytical tool for the risk assessment is urgently needed. The study was conducted to assess possible scenarios of gas accidents and to develop a computer model to minimize the damage. The data from ETA was analyzed intensively, and the model was developed. The model is capable of predicting jet fire influence area with comprehensive input parameters, such as burial depth. The model was calibrated and verified by the historic accident data from Edison Township, New Jersey, the United States. The statistical model was also developed to compare the results of the model in this study and the existing OGP model. They were in good agreement with respect to damage predictions, such as radiation heat coming from 10 meters away from the heat source of gas flame.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.40-49
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• 2016

When a leak occurs in the buried pipelines, The leak locations are able to detected by using the vibration sensors. These leak detection system, intended for incompressible fluid, such as water, are of using the wave propagation velocity and a signal arrival time delay between the sensors. In this paper, to develop a leak location detection system for a compressible fluid such as gas, the conventional detection methods have been studied, improved, and verified through the experiment using the compressed air. It confirmed that it is possible to detect the leak location for compressible fluid in the buried pipelines and to be applicable to the development of a leak location detection system in buried pipelines for gas.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.83-88
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• 1998

가스배관은 주로 도로를 따라 매설되어 있으며, 최근 지하철공사가 도심지에서 도로를 따라 지속적으로 이루어지고 있으므로 지하철공사시 기존에 매설되어 있는 가스배관이 대기로 노출되고 있다. 노출된 배관의 자중을 지탱해 주기 위하여 전용보를 설치한 후 와이어로프를 이용하여 가스배관을 전용보에 매달아 놓은 상태에서 지하구조물 공사를 하고 있으며, 도로는 임시적으로 철판으로 복공하여 사용하고 있는 실정이다. (중략)

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.224-226
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• 2015

지하 매설 배관의 장기적 사용은 배관의 안전성과 건전성이 확보되어야 한다. 이를 위하여 진단, 평가, 보수에 대한 기술을 확보하고 지속적인 모니터링이 필요한 상태이다. 본 연구는 이러한 배관에 대한 건전성 평가를 활용하여 보수우선순위에 따라 배관을 관리할 수 있게 하는 기술을 개발하는 것이다. 이를 위하여 평가를 할 수 있는 모델에 대한 연구 그리고 모델을 실제 도시가스회사의 시스템과 연계하기 위한 기술 개발에 대한 연구가 진행되었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.5
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• pp.65-76
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• 2010

In this paper, earthquake fragility analysis has been comparatively performed with regard to a buried gas pipeline of API X65 which has been widely used in Korea. For this purpose, a nonlinear time-history analyses has been carried out for 15 different analytical models of a buried gas pipeline in terms of the selected 12 sets of earthquake ground motions with 0.1g of scaling interval. Following that, earthquake fragility analyses have been conducted using the maximum axial strain of the pipeline obtained from the nonlinear time-history analyses. Parameters under consideration for subsequent earthquake fragility analyses are soil conditions, end-restraint conditions, burial depth and the type of pipeline. Comparative analyses reveal that whereas the first three parameters influence the fragility curves, particularly soil conditions amongst the three parameters, the last parameter has a little effect on the curves. In all, the present study can be considered as a benchmark fragility analysis of a buried gas pipeline in the absence of an earthquake fragility analysis of the pipeline and thus is expected to be a useful source regarding earthquake fragility analyses of a buried gas pipelines.

• Journal of the Korean Institute of Gas
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• v.2 no.2
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• pp.26-33
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• 1998

The thickness of buried gas pipeline is determined mainly with internal pressure and location factor according to the requirements of ANSI B3l.8. But the stress of buried gas pipeline is determined by not only internal stress but also external loads. The change of burying and environmental conditions, therefore, may result in increasing stress of pipeline. In order to avoid the decrease of safety degree resulting from change of environmental condition, the evaluation of stress level shall be necessary. The reliable equations have been developed for calculating stress of buried pipeline from internal pressure, earth load, vehicle load, ground subsidence. But they are very difficult to understand and use for non-specialist. For easy calculation of non-specialist, the new computer program to calculate stress of buried natural gas pipeline have been developed. The program can calculate maximum stress resulted from earth load, vehicle load, thermal load, four type ground subsidence. The stress is calculated by the equations and extrapolation of the graph resulted from FEM. In this paper, as the series of paper I, the operating method and the functions of the program is explained.

• Journal of the Korean Institute of Gas
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• v.23 no.2
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• pp.9-16
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• 2019

The frequency of major accidents which has probability of occurrence at the high pressure underground pipeline of industrial estate such an Ulsan, Yeo-ju by the other construction such as an excavation work will be compared to city gas underground pipeline to derive the basic event by the FTA and present. Also, Observe and analyze the pipe damage impact factor such as an excavation frequency, patrol cycle. As a result, It contributes to the safety improvement of high pressure gas buried pipeline due to obtain importance and sensitivity of the pipe damge impact factors.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.421-424
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• 2010

최근 노후한 기존 구조물의 교체 및 건물 증축으로 인하여, 도심지 내 공사 현장 및 주변 지반에 매설된 지중 배관은 차량 이동 하중 및 건설 장비 하중 등의 진동에 노출이 되어있는 실정이다. 이러한 장비하중이 매설배관에 미치는 영향을 분석, 예측하기 위하여 실증 실험 결과를 토대로 모델을 검증하고 수치해석을 수행하였다. 그 결과 최대 발생 응력은 외관은 $270^{\circ}$에서, 내관은 $180^{\circ}$에서 발생 하였으며, 이는 폴리우레탄 보온재의 하중 분산 효과로 설명 할 수 있다.