• KCID journal
• /
• v.3 no.2
• /
• pp.44-52
• /
• 1996

To make a real hydraulic simulation model, Hazen-Williams' coefficient must be calibrated using the measured discharges and hydraulic head loss. In this paper, calibrating method of Hazen-Williams' coefficient was proposed for pipeline system. The calibra

• Structural Engineering and Mechanics
• /
• v.6 no.3
• /
• pp.291-304
• /
• 1998

This paper deals with the non-axisymmetric dynamic response of an imperfectly bonded buried orthotropic pipeline subjected to longitudinal wave (P-wave) excitation. An infinite cylindrical shell model, including the rotary inertia and shear deformation effects, has been used for the pipeline. For some cases comparison of axisymmetric and non-axisymmetric responses have also been furnished.

• Smart Structures and Systems
• /
• v.15 no.2
• /
• pp.245-258
• /
• 2015

A methodology based on distributed fiber optic sensors is proposed to detect the lateral buckling for subsea pipelines in this study. Uncontrolled buckling may lead to serious consequences for the structural integrity of a pipeline. A simple solution to this problem is to control the formation of lateral buckles among the pipeline. This firms the importance of monitoring the occurrence and evolution of pipeline buckling during the installation stage and long-term service cycle. This study reports the experimental investigations on a method for distributed detection of lateral buckling in subsea pipelines with Brillouin fiber optic sensor. The sensing scheme possesses the capability for monitoring the pipeline over the entire structure. The longitudinal strains are monitored by mounting the Brillouin optical time domain analysis (BOTDA) distributed sensors on the outer surface of the pipeline. Then the bending-induced strain is extracted to detect the occurrence and evolution of lateral buckling. Feasibility of the method was validated by using an experimental program on a small scale model pipe. The results demonstrate that the proposed approach is able to detect, in a distributed manner, the onset and progress of lateral buckling in pipelines. The methodology developed in this study provides a promising tool for assessing the structural integrity of subsea pipelines.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.3
• /
• pp.1756-1763
• /
• 2014

A water pipeline buried under the riverbed could be exposed by bed erosion, therefore safe crossing sections should be analyzed for preventing damages due to the exposure of pipelines. In this study, flow and bed changes have been simulated using a two-dimensional numerical model for selecting the optimized section of pipeline crossing in the Geum River. As a result of simulation with the 20-year recurrence flood, sediment deposition has been distributed overall in the channel and bed erosion over 2 m has occurred near bridge piers. For the extreme flood simulation, the channel bed near the bridge piers has been eroded down to the buried depth. Therefore, within 140 m upstream of the bridge piers, bed erosion affects a buried pipeline in safety due to bridge pier effects and the crossing section over 150 m upstream of bridge piers is selected as a safe zone of a water pipeline.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.12 s.243
• /
• pp.1574-1585
• /
• 2005

In this paper, a spectral element model is developed for the uniform straight pipelines conveying internal unsteady fluid. Four coupled pipe-dynamics equations are derived first by using the Hamilton's principle and the principles of fluid mechanics. The transverse displacement, the axial displacement, the fluid pressure and the fluid velocity are all considered as the dependent variables. The coupled pipe-dynamics equations are then linearized about the steady state values of the fluid pressure and velocity. As the final step, the spectral element model represented by the exact dynamic stiffness matrix, which is often called spectral element matrix, is formulated by using the frequency-domain solutions of the linearized pipe-dynamics equations. The FFT-based spectral dynamic analyses are conducted to evaluate the accuracy of the present spectral element model and also to investigate the structural dynamic characteristics and the internal fluid transients of an example pipeline system.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.1
• /
• pp.37-45
• /
• 2018

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.

• Journal of the Korean Institute of Gas
• /
• v.7 no.2 s.19
• /
• pp.14-21
• /
• 2003

Frequency analysis of city gas pipeline was studied and then the method to give frequencies of failure by the third-party digging, corrosion, ground movement, and equipment failure which were known to be the major cause of risk of city gas pipeline. The failure by the third-party digging was analyzed by fault tree analysis and the failure by corrosion was analyzed by applying equation calculating remaining strength with time. The failure by ground movement was evaluated by applying modified model which was induced through weighing factors with basic failure rate model. The failure rate of equipment was calculated with both generic and specific data

• Structural Engineering and Mechanics
• /
• v.87 no.3
• /
• pp.211-219
• /
• 2023

The structural health of a pipeline is usually assessed by visual inspection. In addition to the fact that this method is expensive and time consuming, inspection of the whole structure is not possible due to limited access to some points. Therefore, adopting a damage detection method without the mentioned limitations is important in order to increase the safety of the structure. In recent years, vibration-based methods have been used to detect damage. These methods detect structural defects based on the fact that the dynamic responses of the structure will change due to damage existence. Therefore, the location and extent of damage, before and after the damage, are determined. In this study, fuzzy genetic algorithm has been used to monitor the structural health of the pipeline to create a fuzzy automated system and all kinds of possible failure scenarios that can occur for the structure. For this purpose, the results of an experimental model have been used. Its numerical model is generated in ABAQUS software and the results of the analysis are used in the fuzzy genetic algorithm. Results show that the system is more accurate in detecting high-intensity damages, and the use of higher frequency modes helps to increase accuracy. Moreover, the system considers the damage in symmetric regions with the same degree of membership. To deal with the uncertainties, some error values are added, which are observed to be negligible up to 10% of the error.

• Publications of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.37-39
• /
• 2017

We present the first results of a new data analysis pipeline for processing extragalactic AKARI/IRC images. The main improvements of the pipeline over the standard analysis are the removal of Earth shine and image distortion correction. We present the differential number counts of the AKARI/IRC S11 filter in the IRAC validation field. The differential number counts are consistent with S11 AKARI NEP deep and $12{\mu}m$ WISE NEP number counts, and with a phenomenological backward evolution galaxy model, at brighter fluxes densities. There is a detection of fainter galaxies in the IRAC validation field.