Flow-Aware Link Dimensioning for Guaranteed-QoS Services in Broadband Convergence Networks

Lee, Hoon,Sohraby, Khosrow The Korea Institute of Information and Commucation 2006 Journal of communications and networks Vol.8 No.4

In this work, we propose an analytic framework for dimensioning the link capacity of broadband access networks which provide universal broadband access services to a diverse kind of customers such as patient and impatient customers. The proposed framework takes into account the flow-level quality of service (QoS) of a connection as well as the packet-level QoS, via which a simple and systematic provisioning and operation of the network are provided. To that purpose, we first discuss the necessity of flow-aware network dimensioning by reviewing the networking technologies of the current and future access network. Next, we propose an analytic model for dimensioning the link capacity for an access node of broadband convergence networks which takes into account both the flow and packet level QoS requirements. By carrying out extensive numerical experiment for the proposed model assuming typical parameters that represent real network environment, the validity of the proposed method is assessed.

Simulation and modeling of MEG (Monoethylene Glycol) regeneration for the estimation of energy and MEG losses

Son, Hyunsoo,Kim, Yoori,Park, Sangmin,Binns, Michael,Kim, Jin-Kuk Elsevier 2018 ENERGY Vol.157 No.-

<P><B>Abstract</B></P> <P>MEG (Monoethylene glycol) is a hydrate inhibitor used for the recovery of subsea oil and gas. For practical and economic reasons, it is necessary to extract and re-use the MEG through a regeneration unit which removes hydrocarbons, water and salts. The economic performance of regeneration process depends on MEG losses and the amount of heat and power required for the separation. Since recovering as pure MEG as possible without disturbances induced by salts is important to maintain process sustainability, this study focuses on the modeling and simulation of salt and water removal steps, including the prediction of hydrate inhibitors required for subsea condition. Also, design methods presented in this study systematically provide identification of appropriate configurations and operating conditions, with which the economic performance concerning MEG loss and energy consumption can be systematically evaluated. Models are developed in process simulators and validated with industrial data. Hydrate inhibitor recovery of 99.42% from the reclamation unit considered in this study is comparable to typical recoveries reported in commercial processes in the range of 99.4%–99.5%. It is also found that energy used for the separation of MEG from water in re-concentration unit accounts for at least 60% of total energy consumption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Systematic operational analysis of MEG process for ensuring offshore flow assurance. </LI> <LI> Integrated process modeling for the design of MEG reclamation and re-concentration. </LI> <LI> Multi-period design framework for enhancing operability of MEG process. </LI> </UL> </P>

해저생산플랜트 설계를 위한 흐름 견실성 문제에 대한 소고

조경남(Gyungnam Jo),이성근(Sung Geun Lee),장광필(Kwang Pil Chang),최종근(Jonggeun Choe),김윤호(Yunho Kim),최항순(Hang S. Choi) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

Design and operating guidelines for subsea O&G (oil & gas) production systems have been developed to ensure the control of hydrates, wax and other solids, which may impede flow. System designs are primarily driven by the need to avoid the formation of a hydrate plug in any portion of the system. Remediation of hydrate plugs may require system shut-down for weeks or even months. The design and operating guidelines for controlling of solids and hydro-dynamic slugging in the subsea systems are aimed to secure the flow assurance process.

Thermoresponsive Microcarriers for Smart Release of Hydrate Inhibitors under Shear Flow

Lee, Sang Seok,Park, Juwoon,Seo, Yutaek,Kim, Shin-Hyun American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.20

<P>The hydrate formation in subsea pipelines can cause oil and gas well blowout. To avoid disasters, various chemical inhibitors have been developed to prevent or delay the hydrate formation and growth. Nevertheless, direct injection of the inhibitors results in environmental contamination and cross-suppression of inhibition performance in the presence of other inhibitors against corrosion and/or formation of scale, paraffin, and asphaltene. Here, we suggest a new class of microcarriers that encapsulate hydrate inhibitors at high concentration and release them on demand without active external triggering. The key to the success in microcarrier design lies in the temperature dependence of polymer brittleness. The microcarriers are microfluidically created to have an inhibitor-laden water core and polymer shell by employing water-in-oil-in-water (W/O/W) double-emulsion drops as a template. As the polymeric shell becomes more brittle at a lower temperature, there is an optimum range of shell thickness that renders the shell unstable at temperature responsible for hydrate formation under a constant shear flow. We precisely control the shell thickness relative to the radius by microfluidics and figure out the optimum range. The microcarriers with the optimum shell thickness are selectively ruptured by shear flow only at hydrate formation temperature and release the hydrate inhibitors. We prove that the released inhibitors effectively retard the hydrate formation without reduction of their performance. The microcarriers that do not experience the hydration formation temperature retain the inhibitors, which can be easily separated from ruptured ones for recycling by exploiting the density difference. Therefore, the use of microcarriers potentially minimizes the environmental damages.</P>

Recent advances in ionic liquids as alternative to surfactants/chemicals for application in upstream oil industry

Achinta Bera,Jatin Agarwal,Maunish Shah,Subhash Shah,Rakesh Kumar Vij 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.82 No.-

The oil industry is in search of the stable chemicals that can be applied in drilling, stimulation, enhancedoil recovery at high temperature and high salinity reservoirs, unconventional heavy oil recovery bysolvent extraction method, andflow assurance. This quest has opened a new category of research on ionicliquids. In the present review, an attempt is made to explore the ongoing research and development onthe application of ionic liquids in the domain of upstream oil industry. The review provides a deep insightinto the progress and status of current research, challenges and utilization of ionic liquids for drilling,stimulation, enhanced oil recovery, unconventional oil recovery, andflow assurance. It is found from theliterature that ionic liquids can be used to prevent shale inhibition, improve clay stabilization and drillingfluid properties, compose fracturingfluids, control wax and asphaltenes deposition, prevent gas hydrateformation, increase additional oil recovery, and improve unconventional oil recovery. It is also expectedthat the current review will open new avenues for the budding researchers and engineers to utilize ionicliquids in upstream oil and gas industry and to acquire profound ideas for its way forward.

초고속 인터넷 접속망에서 보장형 서비스 제공을 위한 경계 노드의 스케줄링 알고리즘 설계 및 성능 분석

노대철,이재용,김병철 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.4C

최근 초고속 인터넷 접속 서비스에 대한 가입자의 욕구는 단순 인터넷 접속 서비스에서 개인화된 서비스로 변화하고 있다. 초고속 인터넷 접속 서비스 제공 사업자 또한 가입자에게 좀 더 고속의 서비스를 제공하기 위해 ADSL에서 메트로 이더넷 기반의 VDSL로 대체하고 있다. 그러나 이러한 메트로 이더넷 기반의 초고속 인터넷 접속망에 이미 설치된 장비들은 트래픽 특성에 따라 가입자를 구별할 수 없어 개인별로 차별화된 서비스를 제공하는 것은 곤란한 실정이다. 이 논문에서는 접속망이 트리 구조일 경우, 접속망 요소들이 Qos 기능을 제공하지 않아도 경계 노드의 플로우별 트래적 쉐이핑으로 특정 하향 플로우에 대하여 Qos를 제공할 수 있음을 보였다. 본 논문에서는 이를 보이기 위해 트러 구조의 접속망에서 보장형 서비스를 제공하기 위한 경제 노드의 스케줄링 알고리즘을 설계하고, 이것의 성능을 분석하였다. 이 스케줄링 알고리즘은 최대 허용 대역폭으로 각 플로우를 쉐이핑하고, 플로우의 SLA에 따라 최소 대역폭을 보장하도록 DRR을 개량하여 설계되었다. 설계된 알고리즘의 성능을 분석하기 위해 다양한 시뮬레이션을 수행하여, 경계 노드에서의 플로우별 트래픽 쉐이핑에 의해 접속망에서의 혼잡 및 손실이 줄어들고, TCP 트래픽 플로우의 성능이 크게 향상되며, CBR 보장형 서비스에 대한 손실의 큰 감소와 더불어 지연 및 지터 특성이 향상되었음을 보였다. Recently, subscribers have strong desire to get QoS based personalized services in high-speed Internet access. Service providers have been rapidly replacing ADSL, cable broadband access networks with Metro-Ethernet based VDSL. But, it is difficult for Motto-Ethernet based broadband access networks to provide QoS based personalized services, because already deployed network elements cannot distinguish subscribers by specific traffic characteristics. In this paper, when the access network has tree topology, we show that it is possible to provide QoS for each downstream flow with only per flow traffic shaping at the edge node without QoS functions in access networks. In order to show that our suggested scheduling algorithm at the edge node can support the assured service in tree topology access networks, we evaluated its performance by simulation. The suggested scheduling algorithm can shape per-flow traffic based on the maximum bandwidth, and guarantees minimum bandwidth per flow by modifying the DRR scheduler. Simulation results show that congestion and loss in the access network elements are greatly reduced, TCP performance is highly enhanced and loss for assured CBR service flows is reduced by only shaping per-flow traffic at the edge node using our proposed scheduling algorithm.

해저 석유생산시스템에서 유동안정성 확보를 위한 왁스집적 제어기술

임종세,강판상,유승렬 한국자원공학회 2013 한국자원공학회지 Vol.50 No.2

Wax has been serious problem of flow assurance in low temperature environment such as subsea petroleum production system. In reservoir condition, wax is liquid phase, however, it can be crystallized at the temperature under wax appearance temperature. Wax crystal tends to be agglomerated and deposited containing oil, which becomes wax deposits. Wax deposition mechanisms in subsea petroleum production system are molecular diffusion, shear stripping reduction, aging, particle diffusion & inertia effect, shear dispersion, brownian diffusion and gravity settling. Commonly, temperature gradient between internal wall and center flow is major influential factor on wax deposition among oil composition, pressure, flow rate and roughness of flow line wall. To mitigate wax deposition in the subsea production system, thermal management, wax inhibitor and pigging have been widely applied. These technologies and applications at King field, Gannet D field and Cottonwood field are investigated in this study. 해저와 같은 저온환경에서 석유생산 시 빈번히 집적되는 왁스는 저류층에서 석유에 용해되어 있으나 석유의 온도가 왁스생성온도 이하가 되면 결정으로 석출된다. 왁스결정은 서로 결합하면서 오일 등을 함유한 왁스고형물이 되고 석유생산 환경에 따라 분자확산, 전단응력효과, 왁스경화, 확산관성효과, 전단확산, 브라운확산, 중력침전으로 유동관 내벽에서부터 집적된다. 온도, 석유성분, 압력, 유량, 유동관 내벽 거칠기가 왁스집적에 영향을 미칠 수 있으나 일반적으로 유동관 내벽의 온도와 유동단면적 중앙의 온도구배가 왁스집적에 가장 큰 영향을 미친다. 석유의 온도감소율이 커서 왁스집적속도가 가장 빠른 유동관에서의 주요 왁스집적 제어기술은 유동관을 단열 또는 석유를 가열하여 왁스생성온도 이상으로 유지시키는 열제어법, 왁스결정의 성장을 막거나 용해시키는 왁스억제제 주입법, 유동관에 집적된 왁스를 긁어 제거하는 피깅이 있고 이들을 멕시코 만에 위치한 King 유전, Gannet D 유전과 북해에 위치한 Cottonwood 유전의 해저 석유생산시스템에 적용한 사례를 조사하였다.

인터넷 쇼핑몰의 고객충성도 영향요인에 관한연구: 서비스품질과 플로우경험을 중심으로

강문식,김효정 한국인터넷전자상거래학회 2006 인터넷전자상거래연구 Vol.6 No.2

…This research investigates the determinants of customer Loyalty on Internet shopping mall. We propose a theoretical model consisting of independent factors such as tangibility, reliability, responsiveness, assurance, empathy, flow experience, and dependent factors such as satisfaction and loyalty.For examining the relationships proposed by the research model, a field study using a survey methodology for data collection was conducted. The data were analyzed using AMOS based on the structural equation modeling, a second-generation multivariate technique, which has gained distinct advantages over other technique. The result shows that tangibility, reliability, assurance, empathy, flow experience, satisfaction, loyalty have significant effects on the satisfaction and tangibility, reliability, assurance, satisfaction have significant effects on the customer loyalty in Internet business.

OLGA를 이용한 해저 가스 유전의 Slugging 예측

백경록(Kyung-Lok Baek),박상민(Sang-Min Park),박진후(Jin-Hoo Park),장광필(Kwang-Pil Chang) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

As a recognized critical issue in design and operation of subsea oil/gas systems, flaw assurance is an engineering analysis process to assure that hydrocarbon fluids are transferred economically and safely from resemoir to the end user during the life of a project. One of the flow assurance challenges is prediction of the slugging in the subsea pipelines which could potentially block the flow path of hydrocarbon fluids because slugging greatly affects the design of receiving facilities such as separators and slug catchers. Tire facilities can be flooded and damaged if the slug is larger than the receiving capacity of the facilities. Tlw'efore, quantifying the slug volume is a essential part in the design of subsea production plants. The pui'pose of this paper is to analyze the effect of Operating conditions on slug volume in the subsea pipeline system using multiphase flaw simulation code, OLGA. It is shewn that the slug volumes into the separator through the subsea pipelines are affected by the operating conditions, ramp-up scenarios, and tend to be created lower for the conditins of applying the two step ramp-up scenarios rather than the single step and linear ramp-up scenarios.

가스 하이드레이트와 파이프라인 유동 안정성

김용헌(Kim, Yong-Heon),양성오(Yang, Sung-Oh) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.06

Natural gas hydrate has been a major problem for its plugging nature in the pipeline. With the demand of deep-water production, the importance of flow assurance technology, preventing hydrate, asphaltene and wax in the pipeline becomes bigger Kinetic models combined with the flow simulator are being developed to explain the nature of hydrate plug formation in the pipeline. To simulate the hydrate plug formation, each stage including the nucleation, growth and agglomeration should be considered. The hydrate nucleation is known to be stochastic and is believed hard to be predicted. Recent publications showed hydrate growth and agglomeration can be observed rigorously using a particle size analyzer. However properties of the hydrate should be investigated to model the growth and agglomeration. The attractive force between hydrate particles, supposed to be the capillary force, was revealed to be stochastic. Alternative way to model the hydrate agglomeration is to simulate by the discrete element method. Those parameters, particle size distribution, attractive force, and growth rate are embedded into the kinetic model which is combined Into the flow simulator. When compared with the flowloop experimental data, hydrate kinetic model combined into a flow simulator showed good results. With the early results, the hydrate kinetic model is promising but needs more efforts to improve it.