• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.803-806
• /
• 1997

The AC induced voltage on underground pipelines not only do harm to workers and instruments, but also cause big trouble in some case. This paper gives the mechanisms, examples, and countermeasure for the AC induced voltages which are caused by the resistive coupling between the grounding system of the 22.9kV distribution power system and the underground pipeline.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2015.11a
• /
• pp.224-226
• /
• 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 Korean Institute of Gas
• /
• v.20 no.5
• /
• pp.40-49
• /
• 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.

• Journal of the Korean Institute of Gas
• /
• v.10 no.3 s.32
• /
• pp.20-26
• /
• 2006

The survey team has conducted the on-the-site inspection of 53 bridges to which LNG gas pipelines are attached, to ascertain their level of safety, durability and any defect by adapting a method of computer data input process and precision analysis. In this way, we could estimate an effective corrective action on the defective gas pipelines found through this survey. Our survey team has analyzed carefully these 2 defective lines selectively out of 10 lines, which are considered to be most seriously weak. According to our elaborate analysis these two pipelines go over 70% of the set standard stress based on our Safety Manual Scale. We have taken corrective actions on these lines by repairing/replacing/obsolete damaged lines to ensure the distress of the bridges involved with the pipelines and could secure safety.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.3
• /
• pp.201-205
• /
• 2015

This paper describes thermal flow characteristic in various pipelines: straight pipeline and curved pipeline. In the Arctic and ocean area, pipelines are exposed to a extremely low temperature ($0{\sim}-40^{\circ}C$). In this situation, three-dimensional flow analysis should be analyzed to investigate thermal effects such as pressure drop, temperature change, velocity deficit and distribution change of liquid droplet of internal fluid. Also, due to freezing of water droplet, impingement erosion is expected in the curved pipeline. The stability of the pipelines can be influenced by impingement erosion. In this paper, multi-phase and multi-species analysis was introduced to analyze the flow characteristics and impingement erosion of Arctic and ocean pipelines.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.34 no.1
• /
• pp.44-52
• /
• 2014

Leakage is an important factor to be considered for the management of underground water supply pipelines in a smart water grid system, especially if the pipelines are aged and buried under the pavement or various structures of a highly populated city. Because the exact detection of the location of such leaks in pipelines is essential for their efficient operation, a new methodology for leak location detection based on frequency band variation, windowing filters, and probability is proposed in this paper. Because the exact detection of the leak location depends on the precision of estimation of time delay between sensor signals due to leak noise, some window functions that offer weightings at significant frequencies are applied for calculating the improved cross-correlation function. Experimental results obtained by applying this methodology to an actual buried water supply pipeline, ~ 253.9 m long and made of cast iron, revealed that the approach of frequency band variation with those windows and probability offers better performance for leak location detection.

• Smart Structures and Systems
• /
• v.26 no.4
• /
• pp.507-520
• /
• 2020

In order to achieve effective corrosion monitoring of buried metal pipelines, a Novel nondestructive Testing (NDT) methodology using ultra-long (250 mm) Polymer Optical Fiber (POF) sensors coated with the Fe-C alloy film is proposed in this study. The theoretical principle is investigated to clarify the monitoring mechanism of this method, and the detailed fabrication process of this novel POF sensor is presented. To validate the feasibility of this novel POF sensor, exploratory research of the proposed method was performed using simulated corrosion tests. For simplicity, the geometric shape of the buried pipeline was simulated as a round hot-rolled plain steel bar. A thin nickel layer was applied as the inner plated layer, and the Fe-C alloy film was coated using an electroless plating technique to precisely control the thickness of the alloy film. In the end, systematic sensitivity analysis on corrosion severity was further performed with experimental studies on three sensors fabricated with different metal layer thicknesses of 25 ㎛, 30 ㎛ and 35 ㎛. The experimental observation demonstrated that the sensor coated with 25 ㎛ Fe-C alloy film presented the highest effectiveness with the corrosion sensitivity of 0.3364 mV/g at Δm = 9.32 × 10^-4 g in Stage I and 0.0121 mV/g in Stage III. The research findings indicate that the detection accuracy of the novel POF sensor proposed in this study is satisfying. Moreover, the simple fabrication of the high-sensitivity sensor makes it cost-effective and suitable for the on-site corrosion monitoring of buried metal pipelines.

• Journal of the Korean Institute of Gas
• /
• v.21 no.6
• /
• pp.30-38
• /
• 2017

Established in the 1960s, high pressure underground pipelines in Ulsan and Yeosu industrial estate are underground as toxic gas as well as combustible gas that is heavier than city gas and low combustion range. Especially, industrial pipelines occupy more than 20 years old pipes. In this way, the industrial estate pipeline was installed before the introduction of the supervision of construction, However, unlike the city gas pipeline, the pipeline is managed without any legal obligation. In this study, the safety management status of high pressure underground pipelines and urban gas underground pipelines in the industrial estate is analyzed and comparison of laws, extent of damage impact, using the pipe inspection model for pipe inspection of high pressure piping system with the existing piping system. it is intended to cuntribute to improving the safety of industrial estate are underground pipeline.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.11 no.1
• /
• pp.59-66
• /
• 2011

Lifeline Damages induced by earthquake loading brings not only a structure damage but the communication problems by the interruption of various energy utilities such as electric power, gas, and water resources. Earthquake loss estimation systems in USA and Japan, called as HAZUS (Hazard in US) and HERAS (Hazards Estimation and Restoration Aid System), respectively, have been established for the purpose of efficient responding to the earthquake hazard. Sufficient damage records are required to establish these systems. However, there are insufficient data set of damage records obtained from previous earthquakes in Korea. In this study, according to the construction specifications of the pipelines in both Korea and USA, the behavior of both ductile and brittle pipelines embedded in dense sand overlying various soils, such as clay, sand, and gravel were examined with respect to the pipeline characteristics under various earthquake loadings. The applicability of pipeline damage prediction used in HAZUS program to Korea has been investigated.

• Journal of the Korean GEO-environmental Society
• /
• v.22 no.11
• /
• pp.23-29
• /
• 2021

Recently, ground subsidence has been steadily occurring mainly in downtown areas, threatening the safety of citizens. Under the road, various underground facilities such as water supply pipe, sewage pipe, and communication pipe are buried. Due to the aging of these underground facilities and the reckless development of the underground, it is acting as a cause of ground subsidence. Although there is a result of analyzing the risk of ground subsidence according to the deterioration of the existing pipeline, there is no result of analyzing the risk of ground subsidence using the density of pipelines indicating ground disturbance. Therefore, in this study, the density of the underground space was analyzed using the data of six types of representative underground pipelines in Seoul, and a study was conducted on whether there is a correlation with the ground subsidence. As a result, it was found that the density of underground facilities is high in the area where the ground subsidence occurred, indicating that the density of pipelines have an effect on the ground subsidence.