• Journal of Ocean Engineering and Technology
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• v.31 no.2
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• pp.103-110
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• 2017

The temperature of subsea pipeline, approximately as high as $100^{\circ}C$, is significantly higher than the temperature of surrounding sea water and sediment. In this reason, heat can be lost from the subsea pipeline to cause serious operation problem. Therefore it is important that the subsea pipeline must be designed to ensure that heat loss is small enough. Heat loss of unburied pipeline is higher than buried pipeline. For that purpose, trenching and backfilling system is a commonly used method for maintaining flow assurance in subsea pipeline installation. For this commonly used method, knowing thermal conductivity of backfill is essential to protect a heat loss of pipeline. This paper presents thermal conductivity of backfill soil using laboratory model test and numerical analysis for various backfill. In conclusion, it can be seen that higher the sand content of the man-made backfill sample, the higher the thermal conductivity. On the other hand, as the water content increases, the thermal conductivity becomes smaller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.5
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• pp.131-139
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• 2001

In this paper, aerials gas pipeline vibrations due to the passing of vehicles have been measured, and peak values and characteristics of vibration were analyzed. In order to develop isolation system for gas pipeline, six cases with various support condition and hanging method were tested. The hanger used instead of wore rope isolated almost all vibrations transmitted from main beam. In the results of test, we could decrease response of vibration velocity from 49 % to 56 % and response of vertical vibration acceleration from 49 % to 60 %, because hanger instead of wire rope was used and rubber pads instead of wooden shield plates at support positions for Proofing horizontal vibration were used.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.153-156
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• 2002

FFT/IFFT block is very important module to determine the performance of OFDM system. This block has been implemented using several FFT algorithms such as radix-2, radix-4 etc. However SRFFT algorithm has not been implemented because of the complexity for implementation. This paper proposes a serial-pipeline SRFfT for OFDM system. The serial-pipeline SRFFT is optimized to use a serial input and serial output. We have implemented the SRFFT block using anam 0.25 Um five-metal process. The simulation show that the SRFFT block can operate about 200MHz. This architecture could be adapted to IEEE 802.lla wireless LAN standard.

• 연구논문집
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• s.31
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• pp.135-147
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• 2001

The wall-thickness of insulated pipelines can be easily evaluated by measuring the gamma-ray transmission intensity because this intensity is inversely proportional to the thickness of insulated pipeline. The main purpose of this study is to develop the nondestructive and filmless on-line inspection system of corrosion by measuring the wall thickness of insulated pipeline. The inspection system is constructed with radioisotope, 64 channel photo diode array detector, crawler system and data taking and operating software. The traditional off-line radiographic method carried out by exposing film cassettes can be replaced by this cost-effective on-line digital imaging method and the application will be greatly expected especially in the chemical and petrochemical industries.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.13-19
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• 2008

A camprehensive review of the expansion behavior of marine pipelines due to thermal and pressure change is presented based on research work over the last 10 years. The review is organized into five main sections, namely free expansion with uniform temperature, free expansion with temperature gradient, expansion with end restraints, expansion of pipe-in-pipe system, and lateral deviation (snaking). Based on the accumulated knowledge of the interactions between the soil and pipeline behavior, a whole pipeline system can be modeled by an accurate finite element method (FEM). This methodology requires a comprehensive understanding and engineering verification of the expansion behavior of marine pipelines.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.905-910
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• 1991

This paper presets a leakage detection method based on modeling the leakage in pipeline systems. For gas pipeline systems, a method based on the state space model is suggested. For liquid pipeline systems, an experiment based on the static model equation was performed. In the experiment, it was possible to detect the leak and to diagnosis the leak situation within the error of .+-.3%.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.10 no.1
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• pp.1-6
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• 2011

The Underground pipeline facility is a general but most important facility in modern world, but its maintainability has been left behind. An automated and intelligent management technology is needed to prevent the wast of social resource and security. In this paper, we introduce Pipeline Health Monitoring(PHM) with Ubiquitous Sensor Network(USN) for inexpensive structure safety monitoring system, and improve its utility by inventing the advanced impedance converter.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.403-416
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• 2003

There are common features, in both imaging surveys and image processing, between astronomical observations and remote sensing. Handling large amounts of data, in an easy and fast way, has become a common issue. Implementing pipeline software can be a solution to the problem, one which allows the processing of various kinds of data automatically. As a case study, the development of pipeline software for the EIS (European Southern Observatory Imaging Survey) is introduced. The EIS team has been conducting a sky survey to provide candidate targets to the 250 VLTs (Very Large Telescopes) observations. The survey data have been processed in a sequence of five major data corrections and reductions, i.e. preprocessing, flat fielding, photometric and astrometric corrections, source extraction, and coaddition. The processed data are eventually distributed to the users. In order to provide automatic processing of the vast volume of observed data, pipeline software has been developed. Because of the complexity of objects and different characteristic of each process, it was necessary to analyze the whole works of the EIS survey program. The overall tasks of the EIS are identified, and the scheme of the EIS pipeline software is defined. The system structure and the processes are presented, and in-depth flow charts are analyzed. During the analyses, it was revealed that handling the data flow and managing the database are important for the data processing. These analyses may also be applied to many other fields which require image processing.

• Journal of Mechanical Science and Technology
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• v.15 no.9
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• pp.1302-1310
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• 2001

This paper introduces modeling and simulation results for pipeline inspection gauge (PIG) with bypass flow control in natural gas pipeline. The dynamic behaviour of the PIG depends on the different pressure across its body and the bypass flow through it. The system dynamics includes: dynamics of driving gas flow behind the PIG, dynamics of expelled gas in front of the PIG, dynamics of bypass flow, and dynamics of the PIG. The bypass flow across the PIG is treated as incompressible flow with the assumption of its Mach number smaller than 0.45. The governing nonlinear hyperbolic partial differential equations for unsteady gas flows are solved by method of characteristics (MOC) with the regular rectangular grid under appropriate initial and boundary conditions. The Runge-Kuta method is used for solving the steady flow equations to get initial flow values and the dynamic equation of the PIG. The sampling time and distance are chosen under Courant-Friedrich-Lewy (CFL) restriction. The simulation is performed with a pipeline segment in the Korea Gas Corporation (KOGAS) low pressure system, Ueijungboo-Sangye line. Simulation results show us that the derived mathematical model and the proposed computational scheme are effective for estimating the position and velocity of the PIG with bypass flow under given operational conditions of pipeline.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.725-736
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• 2016

There is a growing concern on the improvement of water distribution pipeline for multi-regional water supply system in Korea along with its aging infrastructure. Rehabilitation of large diameter pipeline is more efficient in cost and time compared to replacement with trenching. The procedure for rehabilitation are diagnosis, cleaning, spraying coating material, and final inspection. The internal state of pipeline was carefully diagnosed and got C grade, which required rehabilitation. We found that 17,274,787,000 Korean won could be saved after pipe surface coating because of increased C coefficient of Hazen-Williams equation. Optimal coating material was D polyurea. We also found optimal distance between spraying nozzle and pipe wall to be 70 - 80 cm, which were critical factors for coating quality. This study also illustrated the time for spray drying to be more than 30 min. These results could be used in the quality control process during rehabilitation of aged pipelines.