• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.435-436
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• 2015

국내 도심지 전력계통망을 구성하고 있는 지중송전선로는 345kV, 154kV XLPE 케이블로 건설되고 있다. 도심지의 확장과 수요증가로 선로의 대용량화, 대도체화가 진행되고 있고, 송전용량 증대를 위한 신기술도 역시 지속 발전하고 있다. 새로운 신자재, 신공법이 아닌 케이블 재배치, 매설심도 조정 등 시스템 디자인을 통해 허용전류를 극대화하고, 경제적인 대용량 송전선로를 구축하기 위하여 연구한 송전케이블의 관로 최적시공방안을 소개하고자 한다.

• Journal of the Korean GEO-environmental Society
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• v.19 no.8
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• pp.11-17
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• 2018

Recently, road subsidence has been increasing in urban areas, threatening the safety of citizens. In the lower part of the road, various road facilities such as water supply and drainage pipelines and telecommunication facilities are buried, and the deterioration of the facilities causes the road subsidence. Especially, in the case of old sewer which are attracting attention as a main cause of ground subsidence, the risk of subsidence is calculated indirectly through CCTV exploration. Currently, we are finding cavity through GPR exploration. However, it is difficult to find the sewer back cavity because it is explored from the surface of the road. Thus, the nondestructive cavity exploration techniques was investigated in this study and we confirmed the applicability through experiments on the test-bed. In this study a new quantitative method is proposed to detect the cavity around sewer.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.7-7
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• 2019

중요한 사회기반시설물 중 하나인 상수관망시스템은 대부분의 시설물이 지중에 매설되어있기 때문에 지진에 취약하고 복구에 어려움이 크며, 지진 발생 시 대규모 피해로 이어질 우려가 있다. 따라서 상수관망시스템에 대한 지진피해를 최소화하고 재해로부터 신속하게 복구하기 위한 적절한 복구전략을 마련할 필요가 있다. 상수관로에 발생하는 지진피해는 크게 파손과 누수로 구분되며, 대구경 관로가 파손될 경우 대규모 단수 및 피해가 우려되므로 신속한 복구전략이 마련되어야한다. 일반적으로 파손 관로의 복구는 먼저 피해 관로 인근의 제수밸브의 차폐를 통해 통수를 차단한 후 교체 작업을 진행하는 것이 일반적이며, 해당 과정에서 밸브 차폐에 의한 단수구역의 발생이 불가피하다. 이러한 단수구역 발생은 해당 지역의 용수공급능력 저하로 이어지며, 단수구역의 범위 및 단수용량의 규모는 제수밸브의 위치 및 개수에 따라 결정된다. 본 연구에서는 기개발된 상수관망 지진피해복구 시뮬레이션 모형(Choi et al., 2018)을 개선하여 지진피해복구 시 시스템 내 제수밸브의 설치 위치와 개수에 따라 발생되는 단수구역과 단수상황이 상수관로의 용수공급능력(Serviceability)에 미치는 영향을 분석하였다. 개선된 모형은 피해복구에 따른 용수공급능력을 정량적으로 산정할 수 있으며, 피해 관로의 복구 시 제수밸브 차폐에 의해 발생되는 단수구역을 탐색한 후, 수리해석 모의에 적용함으로써 현실적인 용수공급 상황을 모의할 수 있도록 개선되었다. 또한, EPANET3.0의 Full-PDA(Pressure driven analysis)를 이용함으로써 지진과 같은 비정상상황(다수관의 파손에 따른 압력저하)에서 좀 더 현실적인 수리해석이 가능하도록 개선되었다. 본 연구에서는 해당모형을 실제관망에 적용하여 제수밸브 설치개수 및 위치가 지진피해복구에 미치는 영향을 비교 분석하였으며, 또한 효율적인 지진피해복구 방안을 제시하였다.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.13-19
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• 2007

This study examines a cause for damage of synthetic resins straight pipe occurred after pipe construction of underground electric power duct pipelines of ${\bigcirc}$ section work, ${\bigcirc}$ line, ${\bigcirc}{\bigcirc}$ city railroad. For this, we analyzed a parameter used for plan and structural analysis through a literature review. And the site condition was analyzed in detail, and test construction of the pipe line that simulated the site pipe line and test on compaction by watering were performed. In addition, an examination on subsurface settlement influence of foundation ground through a structural safety and a numerical analysis of power transmission pipe line was performed. As a result of the performance, relative density gained by compaction by watering was more than average and relative degree of compaction according to technical specification standard showed the result of about 90% in the case of good compaction by watering.

• Tunnel and Underground Space
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• v.27 no.6
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• pp.387-392
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• 2017

Recently, road cave-ins, also referred to as ground sinking, have become a problem in urban environments. Public utility facilities such as sewage pipelines, communications pipes, gas pipes, power cables, and other types of underground structures are installed below the roads. It was reported that cave-ins are caused by the aging and lack of proper maintenance of underground facilities, as well as by construction problems. A road cave-in is first initiated by the formation of cavities typically induced by the breakage of underground pipelines. The cavities then grow and reach the base of the pavement. The traffic load applied at the surface of the roads causes an abrupt plastic deformation. This type of accident can be considered as a type of disaster. A road cave-in can threaten both human safety and the economy. It may even result in the loss of human life. In the city of Seoul, efforts to prevent damage before cave-ins occur have been prioritized, through a method of discovering and repairing joints through the 3D GPR survey.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.102-109
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• 2005

In this study, a prototype model of earthquake loss estimation method will be proposed for the quantitative and qualitative damage evaluation of buried pipeline subjected to Permanent Ground Deformation(PGD) due to liquefaction. With this objective, domestic and foreign status of the arts related with earthquake loss estimation method is summarized at first. Domestic development of computer aided earthquake loss estimation method seems to be difficult for the time being. Thus, referring to HAZUS : Earthquake Loss Estimation Methodology which is developed by FEMA (Federal Emergency Management Agency) and NIBS (National Institute of Building Sciences), earthquake loss estimation procedure of buried pipeline subjected to PGD due to liquefaction are proposed, and then exemplary loss estimation are executed. Considering that there have been no practical earthquake loss estimation method and procedure in Korea, the research accomplishments such as above are considered to be helpful for the substantial development of earthquake loss estimation method of buried pipeline subjected to PGD due to liquefaction.

• 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.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.358-365
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• 2006

In this study, fragility curves of continuous buried pipelines subjected to transverse PGD (permanent ground deformation) due to liquefaction are proposed. For the waterworks system, continuos buried pipelines made of ductile iron, poly ethylene, and poly vinyl chloride are analyzed and fragility curves are drawn. Fragility curves are based on the repetitive analyses results and formulated with the dominant factors of behaviour of buried pipeline. With the use of fragility curves, engineers can estimate the status of damage of buried pipeline without overall knowledge of relevant features. Especially, fragility curves proposed in this study will act as a major module of earthquake loss estimation method. Moreover, critical value of magnitude and width of transverse PGD (by which the full damage status of buried pipelines are induced) are estimated. With the use of regression curves of these values, pre evaluation of seismic safety of buried pipelines located within liquefaction hazardous region will be possible.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.4
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• pp.341-353
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• 2022

Pipelines are buried in urban area, and the position (depth and orientation) of buried pipeline should be clearly identified before ground excavation. Although various geophysical methods can be used to detect the buried pipeline, it is not easy to identify the exact information of pipeline due to heterogeneous ground condition. Among various non-destructive geo-exploration methods, ground penetration radar (GPR) can explore the ground subsurface rapidly with relatively low cost compared to other exploration methods. However, the exploration data obtained from GPR requires considerable experiences because interpretation is not intuitive. Recently, researches on automated detection technology for GPR data using deep learning have been conducted. However, the lack of GPR data which is essential for training makes it difficult to build up the reliable detection model. To overcome this problem, we conducted a preliminary study to improve the performance of the detection model using finite difference time domain (FDTD)-based numerical analysis. Firstly, numerical analysis was performed with homogeneous soil media having single permittivity. In case of heterogeneous ground, numerical analysis was performed considering the ground heterogeneity using fractal technique. Secondly, deep learning was carried out using convolutional neural network. Detection Model-A is trained with data set obtained from homogeneous ground. And, detection Model-B is trained with data set obtained from homogeneous ground and heterogeneous ground. As a result, it is found that the detection Model-B which is trained including heterogeneous ground shows better performance than detection Model-A. It indicates the ground heterogeneity should be considered to increase the performance of automated detection model for GPR exploration.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.43-50
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• 2015

Lightweight Foamed Soil (LWFS) is a useful material for underground pipe backfill because of reusability of excavated soil and no compaction effect. In this research, a pilot test is carried out and monitoring results are analyzed to investigate behaviors of a flexible pipe, when LWFS is applied as a backfill material. Simultaneously, they are compared with another test case which is backfilled with Saemangeum dredged soil. As a result, the vertical earth pressure of the case backfilled with LWFS slurry presents that decreases as much as 25.6% in comparison with dredged soil and it is only within 10% after solidification. In case backfilled with dredged soil, the horizontal earth pressure is more than 3.6 times of the case used by LWFS and the vertical and horizontal deformation is more than 3.2 and 2.6 times of the case, respectively. It presents excellent effects on earth pressure and deformation reduction of LWFS. The stresses measured at the upper side of the pipe generally present compressive aspects in case backfilled with dredged soil. However, they present tensile aspects in case of LWFS. It is because of negative moment occurred at the center of the pipe due to the buoyancy from LWFS slurry. Conclusively, LWFS using Saemangeum dredged soil is very excellent material to use near the area in comparison with the dredged soil. However, the countermeasure to prevent the buoyancy is required.