• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.286-296
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• 2016

Offshore CCS technology is to transport and inject $CO_2$ which is captured from the power plant into the saline aquifer or depleted oil-gas fields. The more accumulated injected $CO_2$, the higher reservoir pressure increases. The increment of reservoir pressure make a dramatic change of the operating conditions of transport and injection systems. Therefore, it is necessary to carefully analyze the effect of operating condition variations over the injection period in early design phase. The objective of this study is to simulate and analyze the $CO_2$ behavior in the transport and injection systems over the injection period. The storage reservoir is assumed to be gas field in the East Sea continental shelf. The whole systems were consisted of subsea pipeline, riser, topside and wellbore. Modeling and numerical analysis were carried out using OLGA 2014.1. During the 10 years injection period, the change of temperature, pressure and phase of $CO_2$ in subsea pipelines, riser, topside and wellbore were carefully analyzed. Finally, some design guidelines about compressor at inlet of subsea pipeline, heat exchanger on topside and wellhead control were proposed.

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.17-25
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• 2017

Recently, the need of alternate energy resources is increasing due to the global warming issue. The natural gas buried in the extremely cold regions of Alaska and Siberia is of much interest these days. However, the construction standards are needed to be used in extremely cold regions. Particularly, more research work need to be carried out on the trench stability so that the safety of the workers is ensured and the damage to the construction machinery can also be reduced resulting in smaller construction period. In this study, the process for lowering of the pipelines of 30 and 40 in. diameters in the ground conditions (silt and peat) of Yakutsk, Russia was analyzed. The slopes of the ground surface were considered as $0^{\circ}$, $10^{\circ}$, and $20^{\circ}$ to be excavated in summer and winter. The analysis results show that the weight of pipelayer affects the trench stability. Numerical analysis was performed by considering the types of pipelayers, distance between the trench and pipelayer, and the distance between the pipelayers placed longitudinally along the trench. The results show that as the distance between the pipelayer and the trench decreases, the factor of safety of the slope decreases with an increase in the slope of the ground surface. When the slope of the ground surface was $20^{\circ}$, the breakout surface was anticipated to continue from the pipelayer to the trench boundary. In winter season, stability problem of the trench was not observed when the slope of the ground surface was less than $20^{\circ}$.

• JOURNAL OF ELECTRICAL WORLD
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• s.264
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• pp.18-26
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• 1998

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.230-235
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• 2016

The purpose of this study is to evaluate the gas leakage for a 30-inch ball valve. The ball valve was designed and manufactured for a natural gas transportation through a long-distance pipeline mainly installed in the permafrost region. The gas leakage assessment is based on the pressure testing criteria of international standards. Pressure conditions of the gas leakage test was employed 70 bar, 100 bar, and 110 bar. The amount of the gas leakage at each pressure condition was small and had a value under the pressure testing criteria, ISO 5208. Gas leakage with respect to the test pressure was predicted by the polynomial curve fitting using the experimental results. It is found that the gas leakage rate according to the pressure is proportion to a second order curve.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.337-343
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• 2012

This work investigates the vibrational characteristics of the underground gas pipelines. Experiments were conducted to analyze the effects of various parameters on the vibrational characteristics from the emergency detection point of view. Influences of the various types of impact exerted on the pipe, height of free fall and measuring locations were analyzed. Especially, the difference between the vibrational signal generated by the direct impact on the pipe and the ambient noise was successfully identified. To validate the experimental observation, computer simulation was also performed with constant properties(elasticity, fluid velocity and internal pressure) which are directly conjectured from the accompanying experiment with a real pipe system.

• Geotechnical Engineering
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• v.20 no.4
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• pp.38-49
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• 2004

해상 반사법탐사는 해저 지반의 지층구조를 파악하는 기술로서 해저지층에 부존하는 가스나 골재 등 해저자원 탐사와 해저의 저장시설 건설, 파이프라인 설치 등 다양한 해양 토목공사를 위한 지반조사에 사용된다. 해상 반사법탐사의 기본적인 원리는 해수면 근처에서 인공적으로 음파를 발생시켜 해저면 하부의 지층으로 침투시키면 서로 다른 물성을 갖는 지층의 경계면에서 일부 음파는 반사되는데, 이 반사파를 수신하는 것이다. 탐사과정에서 얻어진 트레이스에는 반사파 이외에도 직접파, 다중반사파와 같은 잡음이 섞여있는데 자료처리를 통해 탄성파 단면도를 작성하고, 이를 해석하여 해저지반의 지질학적 구조를 파악하는 것이 해상 반사법탐사의 목적이다.

• Fire Science and Engineering
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• v.22 no.1
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• pp.10-15
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• 2008

In this study, seismic design in sprinkler head pipeline of water extinguishing system has been carried out. This study describes a generation of artificial earthquake wave compatible with seismic design spectrum, and also analyzed the dynamic response spectra by the simulated earthquake motion. This study constructed powerful engineering base for seismic design, and presented seismic design techniques of water and gas extinguishing piping system. Also, this study readied basis that can apply seismic design and performance estimation of fire fighting system and performance rating as well as pipeline of water extinguishing system from result of this research. Hereafter, if additional research by earthquake magnitude and ground kind is approached, reliance elevation, safety raising and performance based design of fire fighting system see to achieve.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.443-448
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• 2014

This paper describes thermal flow characteristics in various pipelines: straight pipeline and curved pipeline. In the permafrost area, pipelines are exposed to an extremely low temperature ($-40^{\circ}C$). 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. In this paper, multi-phase and multi-species analysis was introduced to analyze the flow characteristics of permafrost pipelines on the vertical support members above ground.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.149.1-149.1
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• 2010

가스 하이드레이트는 작은 고체 부피 내에 막대한 양의 가스를 저장할 수 있다는 특징으로 인하여 최근 주목을 받고 있지만, 엔지니어링 분야에서는 천연가스 수송 파이프라인에 blockage problem을 일으키는 해로운 물질로 처음 관심을 받았다. 이러한 문제를 해결하기 위한 방법으로 초기에는 하이드레이트 형성영역을 벗어나도록 온도, 압력을 유지하기도 하였으나, 최근에는 다양한 형성 억제제가 사용되고 있다. 본 연구에서는 기존에 억제제로 알려져 있는 대표적인 알코올 화합물인 에탄올을 이용하여 고압의 메탄과 binary 하이드레이트의 형성 연구를 수행하였다. 다양한 농도의 에탄올을 이용하여 형성된 하이드레이트 샘플은 고체 NMR 분석을 통하여 분자 거동을 자세히 측정하였으며, 분말 XRD 분석을 통하여 헝성된 미세 결정 구조도 확인하였다. 본 연구에서 얻어진 결과는 에탄올 및 알코올 화합물의 가스 하이드레이트 형성 거동 및 binary guest 시스템에서의 tuning 효과에 대한 유용한 정보를 제시할 수 있을 것이라 판단된다.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.106-112
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• 2017

The present study describes flow induced noise generated from a ball valve used for a gas pipeline. Noise generation from a ball valve mainly induces by interference between unstable(or fluctuating) leakage flow and pipe wall when the ball valve is working closed or opened. To measure the positions of the noise source and the amplitude of noise with respect to measuring frequencies, a commercial acoustic camera is introduced. Noise characteristics generated by the ball valve have been performed by four valve opening rates: 30, 50, 70 and 100 percents. It is noted that 100 percent opening rate means that the valve is fully opened. Throughout the experimental measurements using the acoustic camera, the location of the noise source and the noise amplitude with respect to the frequencies for the test ball valve are clearly evaluated. It is found that the dominant frequencies come from the fluctuating flow at the downstream of the ball valve for four opening rates are observed between 3,000Hz and 3,200Hz. Maximum noise amplitude comes from the ball valve reaches 75dB at the valve opening rate of 50 percent.