• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.6
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• pp.64-74
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• 1999

The frequency of earthquake occurrence tends to increase in Korea. Therefore, the stability of pipeline, such as watersupply pipe, gas pipe, and oil pipe etc. across fault zones in Gyoung-sang landmass is very important, expecially , in metropolitan area. There were some examples of the construction of buried pipeline across fault zones in Korea. the interactiion between the buried pipeline across fault zones and the ground is considered. As well, in the interfaces of them, the direct shear numerical analysis model including elasto-plastic joint element is assumed that the retained dilatancy theory in them, otherwise. Also, the other elements are modeled the ground is nonlinear elastic coutinuaus beam, respectively. In this study, the maximum shear force point exist inside retaine zone(anchored zone) during shwar (as fault sliding), and the distribution of pipeline's behavior is all alike them of pipeline buried in ladnsliding grounds. Since the pipeline is not continuous beam but jointed by steel-pipe segments , practically, on acting of a large bending moment or a shear force, then, those are may be unstable. The reaearch on this point may be new approach.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.3
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• pp.146-159
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• 2016

This study used Navier-Stokes Solver(LES-WASS-2D) for analyzing hydrodynamic characteristics with high order in order to analyze self-burial mechanism of pipeline with spoiler under steady flow. For the validity and effectiveness of numerical model used, it was compared and analyzed with the experiment to show flow characteristics around the pipeline with and without the spoiler. And the hydraulic(flow, vortex, and pressure) and force characteristics were numerically analyzed around the pipeline according to the incident velocity, and shape and arrangement of spoiler. Primarily, if the spoiler is attached to the pipeline, the projected area is increased resulting in higher flow velocity toward the back and strong vortex caused by wake stream in the back. Secondly, the spoiler causes vertically asymmetric flow and vorticity fields and thus asymmetric pressure field. It increases the asymmetry of force on the pipe and thus develops large downward fluid force. Both of them are the causes of selfburying of the pipeline with spoiler.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.15-16
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• 2015

해저파이프라인 및 해저케이블 설치해역이 대수심으로 이동함에 따라 육지와는 다른 열악한 시공 환경에 놓이게 된다. 이때 파이프라인 및 케이블이 매설되는 해저지반 상태와 작업이 이루어지는 해역의 해상조건 등은 작업효율에 영향을 미치기 때문에 효율적인 시공이 필요하다. 본 논문은 구조물 매설에 앞서 해저지반 굴삭 작업을 수행하기 위해 ROV 트렌쳐의 하단에 장착되는 워터젯 굴삭기의 작업효율 및 시공성능 추정에 관한 연구이다. 먼저 전산유체해석을 통해 워터젯 굴삭기의 굴삭효율을 극대화할 수 있는 노즐 수량을 정하였고, 모형실험을 수행하여 굴삭기의 시공성능을 예측할 수 있는 최대 굴삭심도 및 최대 굴삭속도를 파악하였다. 이를 바탕으로 실제 운용중인 워터젯 굴삭장비들과 시공성능을 비교 분석하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.451-458
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• 2004

The study was focused on the development of computational scheme in three dimensional configurations by applying effective heat capacity model to the numerical procedure in order to predict the temperature profiles of a buried pipeline and the frozen penetration depth(FPD) of a freezing soil medium. To realize this, the investigator conducted the unsteady state heat transfer analysis, using the commercial code ABAQUS, for the freezing granite soil medium including a pipeline in a closed system. The proposed model took into consideration the phase change effect of in situ pore water in the frozen fringe. The comparison of results obtained by the proposed model and the actual performances was valuable in establishing a level of confidence in the application of introduced theory.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.1-10
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• 1997

The interaction of ground ice features with underlying seabed is one of the major considerations in the design of Arctic pipeline systems. Regarding the development of offshore gas field near Sakhalin Island, which is an ice-infested area, in this paper an ice scour model to determine the burial depth of Arctic offshore pipeline is studied. Using a simplified ice-seabed interaction process, ice scour depth is easily estimated. This nonlinear numerical model can simulate the scouring process for various enviromental parameters such as ice mass, incoming velocity, soil strength. This study also deals with interaction forces during the scouring process in sloping seabed conditions and discusses the ice loads that are transmitted through the seabed soil.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.114-117
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• 2010

에너지자원(석유, 천연가스, 전기) 이송과 정보전달(해저광케이블)을 위한 다양한 형태의 해저 매설관이 해저면에 설치되어 운영이 되고 있다. 이들 매설관은 지진 또는 해저사면의 유실과 같은 자연재해로 인해 파괴되는 일들이 빈번하게 발생되고 있다. 그 외 태풍 등에 의해 발생되는 파랑하중에 의해서도 이들 매설관이 종종 파괴되는 일이 발생되기도 한다. 태풍 등에 의한 파랑하중은 해저지반에 과다한 과잉간극수압을 발생시켜 지반 액상화를 유발 세굴을 발생시키는데 이로 인해 매설관 하부에는 과도한 인장응력이 유발되어 매설관의 파괴 문제가 야기된다. 만약 석유수송 해저매설관이 파괴되면 경제적?산업적 측면에서 직접적인 피해 이외에도 해양환경에 미치는 영향은 매우 크다고 볼 수 있다. 따라서 파랑하중에 의한 해저매설관 주변 지반의 거동 분석 및 안정성 평가에 관한 연구가 요구된다.

• Journal of the Korean Magnetics Society
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• v.16 no.6
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• pp.305-308
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• 2006

Magnetic flux leakage (MFL) pigs are traditionally used for the detection of gross corrosion on steel pipelines used for the transmission of natural gas. Alternative nondestructive evaluation (NDE) modalities are required for the detection of stress corrosion cracking (SCC) which tends to exist in colonies oriented axially along the length of the pipeline. This paper describes the use of multiphase rotating magnetic fields in the remote region of the probe as a possible SCC detection mechanism. Details of a prototype pig and test rig are given and the challenges associated with the finite element modeling of the device are discussed. Initial experimental results show that this novel NDE modality is sensitive to axially oriented tight cracks.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.151-153
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• 2013

최근 해양에너지플랜트 및 도서지역을 연결시키기 위한 해저 파이프라인 및 통신, 전력 케이블 매설공사가 빈번하게 이루어지고 있다. 특히, 연안항로를 가로지르는 해저케이블 매설공사에는 준설장비를 동원하여 해저부를 굴착하고 케이블을 부설한 후 상단을 덮어 보호하는 일련의 작업과정이 행해지며 이 과정에서 해저저질의 상태, 준설심도, 조류 또는 연안류의 흐름강도, 수심, 통항선박 등 다양한 조건에 따라 단면의 굴착심도 및 폭이 결정되며, 작업의 순서 또는 방법에 따라 여굴의 정도도 변하게 된다. 본 연구에서는 우리나라 서해안 실제해역에서 연안 도서를 연결하는 전력, 통신망의 개통을 위한 해저케이블 부설과 관련한 굴착단면의 실태를 실제 현장여건과 관련해서 적정단면과 준설물량의 산정을 다루어 해저환경변화에 대처하기 위한 기초자료를 제공하고자 하였다. 이를 위하여 대상해역에서 주요설계 지침에 따른 해저부 굴착단면의 평가와 적정단면을 검토하였으며, 이 단면에 따른 준설 적정물량을 산정하여 작업공정에 활용할 수 있도록 하였다.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.158-165
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• 2003

The object of this work is to develop an assessment system for pipeline integrity. The internal algorithm and the database of the system are described in this paper. The system consists of four module applications; the effect of corrosion in pipeline, crack, SCC (stress corrosion cracking) and fatigue module. The database of the system is separated to mainly four parts; geometry of pipeline, material properties, boundary condition and general properties. This system may give a guideline for maintenance and modifications.

• Journal of Ocean Engineering and Technology
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• v.30 no.4
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• pp.310-319
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• 2016

If a spoiler was attached to the pipeline investigated in a previous study, a strong flow and vortex at the lower part caused scouring and thus an asymmetric pressure distribution, which assisted in the analysis of the self-burial structure where a down force was applied to the pipe. However, only the fluid-pipe interaction was considered, excluding the medium (seabed), when practically burying the pipeline. Thus, this study applied a numerical model (LES-WASS-2D) to directly analyze the non-linear interactions among the fluid, pipe, and seabed in order to perform numerical simulations of a pipeline with a spoiler installed on the seabed. This allowed the self-burial mechanism of a pipeline with a spoiler to be analyzed in the same context as the previous study that considered only the fluid-pipe interaction. However, when a pipeline was installed on the seabed, a strong flow and vortex were found at the front of the bottom, and a spoiler accelerated the fluid resistances. This hydraulic phenomenon will reinforce the scouring and down force on the pipeline. In the general consideration of the numerical analysis results by the specifications and arrangements of the spoiler, a pipeline with a spoiler was found to be the most effective for the self-burial function.