• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.1
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• pp.19-23
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• 2010

The Electromagnetic Interference could occur due to power line on the telecommunication service. The Countermeasure is practised by legal law. Various affecting factors are described in the law. In this paper, an effect by pipeline especially in the ground, power feeding plant, and curved railway sector is analyzed as environmental factors which are not included in the law. By the practical measurement, it appears that the measured voltages on the spots with underground pipeline are grouped into lower voltage level, induced voltage tends to be high near power feeding plant, and also in the curved railway line. These analytical results can be meaningly considered in the application of countermeasure.

• Journal of Magnetics
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• v.18 no.3
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• pp.357-360
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• 2013

A modified SQI method using magnetic leakage flux (MFL) signal for underground gas pipelines' defect detection and characterization is presented in this paper. Raw signals gathered using MFL signals include many unexpected noises and high frequency signals, uneven background signals, signals caused by real defects, etc. The MFL signals of defect free pipelines primarily consist of two kinds of signals, uneven low frequency signals and uncertain high frequency noises. Leakage flux signals caused by defects are added to the case of pipelines having defects. Even though the SQI (Self Quotient Image) is a useful tool to gradually remove the varying backgrounds as well as to characterize the defects, it uses the division and floating point operations. A modified SQI having low computational complexity without time-consuming division operations is presented in this paper. By using defects carved in real pipelines in the pipeline simulation facility (PSF) and real MFL data, the performance of the proposed method is compared with that of the original SQI.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.33-38
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• 2018

Defects in piping caused by corrosion or external impact of underground piping can lead to high risk of rupture of the piping due to high pressure. Flammable gas can be immediately ignited when discharged from piping, causing a jetfire. The damage of the radiant heat not only threatens the health of the workers who work in the industry but also the health of the people living in the neighboring residential areas. It is important to prevent and prepare before an accident occurs. In this study, three types of flammable gas underground piping accident scenarios were investigated, and the ranges of influence were determined using Phast ver7.2. and finally regression models were formulated to predict the ranges using excel and Matlab.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.66-71
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• 2014

Gas pipelines are the core facilities in the gas facilities and the most pipelines are buried underground and are exposed to the risk of corrosion caused by the soil characteristics and the environmental impact. The anti-corrosion potential and the corrosion status of the underground pipelines are measured periodically in accordance with the relevant laws and regulations. A study on the cathodic protection measurement system was carried out in order to solve the problems of the conventional measurement system. This paper describes the survey on the standards and the specifications of the cathodic protection measurement and the the reference electrode to meet the relevant regulations, and the development of the measuring circuit and the data transmission module to build the cathodic protection measurement system. This study verified the field applicability through the testing of the developed prototype and investigated on the problems of the previous studies and the future research and development direction.

• 한국가스학회:학술대회논문집
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• 2002.05a
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• pp.111-121
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• 2002

천연가스 수송배관은 매설환경시의 방식 및 외부충격 등에 대비하여 배관을 보호할 목적으로 폴리에틸렌(polyethylene)으로 피복(coating)되어 있다. 가스배관이 전국으로 확장됨과 더불어 배관피복 기술도 초기 사용하던 1층(one-layer), 2층피복으로 발전되어 현재는 3층피복시스템을 적용한 배관들이 전국에 매설되고 없다. 그러나 강관에 적용된 폴리에틸렌 피복이 경우에 따라 장기간 사용에 따른 자연균열등이 발생하여 피복의 안정성에 문제를 일으키기도 하므로, 그동안 전국에 매설되어있는 배관 피복재들의 물성변화 여부를 확인하여 천연가스수송용 배관의 내성 데이터베이스를 구축, 향후 배간운영의 신뢰성 평가에 참고하고자 하였다. 이를 위하여 선진외국에서 폴리에틸렌 배관의 내구성과 장기사용 안정성 평가를 위해 오래전부터 활용되고 있는 저속균열저항성(slow crack growth resistance : SCGR) 측정과 배관 피복층의 산화유도시간(OIT : oxidation induction time)을 측정하여 국내 배관 피복재들의 내구성을 평가하고 이를 근거로 하여 국내사용판정에 적합하고 수출도 고려한 폴리에틸렌 물성치의 목표값을 제안하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.765-770
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• 2010

In this study, the behavior of underground pipeline subjected to pile driving is examined using the verified finite element model based on the field experiment. Young's modules of surface soil is varied and elastic modulus of the other soil layer is fixed. The pile driving force model proposed by Mounir E. Mabsout in 1999 was used and it was functions of time and of force. The forcing function applied on this study considers the kinetic energy of ram located at 1.2m height with 7 tonf. The 3-layered pipeline is composed of steel(inner) pipe, PUR(Polyurethane Resin, filler) and HDPE(outer) pipe, and the length/diameter of main steel pipe is 20m/0.8m(O.D). It is used for district heating pipes in Korea. The results are expressed in terms of Von Mises stress, displacement, and vibration velocity for each soil condition. From the results of the analyses, PUR which is originally intended as a thermal insulation of inner pipe shows performance as a structural member which distributes external pressure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.963-971
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• 2022

Water pipeline network in local and metropolitan area is buried underground, by which it is hard to know the degree of pipe aging and leakage. In this study, assuming various sensor combinations installed in the water pipeline network, the optimal algorithm was derived by predicting the water flow rate and pressure through artificial intelligence algorithms such as linear regression and neuro fuzzy analysis to examine the possibility of detecting pipe leakage according to the data combination. In the case of leakage detection through water supply pressure prediction, Neuro fuzzy algorithm was superior to linear regression analysis. In case of leakage detection through water supply flow prediction, flow rate prediction using neuro fuzzy algorithm should be considered first. If flow meter for prediction don't exists, linear regression algorithm should be considered instead for pressure estimation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.134-141
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• 2011

There have been increased economic and societal demands to continuously monitor the integrity and long-term deterioration of civil infrastructures to ensure their safety and adequate performance throughout their life span. However, it is very difficult to continuously monitor the structural condition of the pipeline structures because those are placed underground and connected each other complexly, although pipeline structures are core underground infrastructures which transport primary sources. Moreover, damage can occur at several scales from micro-cracking to buckling or loose bolts in the pipeline structures. In this study, guided wave measurement can be achieved with a self-sensing circuit using a piezoelectric active sensor. In this self sensing system, a specific frequency-induced structural wavelet response is obtained from the self-sensed guided wave measurement. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented using the damage indices extracted from the guided wave features. Different types of structural damage artificially inflicted on a pipeline system were investigated to verify the effectiveness of the proposed SHM approach.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.171-178
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• 2010

Pipeline structure is one of core underground infrastructure which transports primary sources. Since the almost pipeline structures are placed underground and connected each other complexly, it is difficult to monitor their structural health condition continuously. In order to overcome this limitation of recent monitoring technique, recently, a Ubiquitous Sensor Network (USN) system based on on-line and real-time monitoring system is being developed by the authors' research group. In this study, real-time pipeline health monitoring (PHM) methodology is presented based on electromechanical impedance methods using USN. Two types of damages including loosened bolts and notches are artificially inflicted on the pipeline structures, PZT and MFC sensors that have piezoelectric characteristics are employed to detect these damages. For objective evaluation of pipeline conditions, Damage metric such as Root Mean Square Deviation (RMSD) value was computed from the impedance signals to quantify the level of the damage. Optimal threshold levels for decision making are estimated by generalized extreme value(GEV) based statistical method. Throughout a series of experimental studies, it was reviewed the effectiveness and robustness of proposed PHM system.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.379-381
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• 2003

The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. This causes induced voltages on underground metallic pipelines due to the power line currents. This could cause AC corrosion in the pipeline, which could in turn lead to disastrous accidents, such as gas explosion or oil leakage. This paper investigates for the limitation of induced voltage on the buried metal structures which is used in the inside and outside of the country. And then we measure the earth resistance and leakage current of 22.9kV distribution lines and pipe to soil potential of near pipelines in Seoul Korea. Hereby we can see the leakage current flowing through the earthing electrode have an effect on near pipelines.