• Title/Summary/Keyword: RAFT

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Performance Analysis and Optimization of OpenDaylight Controller in Distributed Cluster Environment (분산 클러스터 환경에서 오픈데이라이트 컨트롤러 성능 분석 및 최적화)

  • Lee, Solyi;Kim, Taehong;Kim, Taejoon
    • KIPS Transactions on Computer and Communication Systems
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    • v.6 no.11
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    • pp.453-462
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    • 2017
  • OpenDaylight is an SDN (Software Defined Networking) open source framework, which is popular in network fields recently. This paper analyzes the performance of a controller cluster architecture by focusing on distributed datastore and Raft leader election algorithm. In addition, we propose an enhanced version of Raft algorithm in order to improve the performance of distributed datastore by distributing shard leaders over controller cluster. This paper compares the conventional Raft algorithm with the proposed version of the Raft algorithm. Moreover, we compare the performance of distributed datastore according to shard roles such as leader and follower. Experimental results show that Shard leaders provide better performance than followers and Shard updating requests need to be distributed over multiple controllers. So, by using proposed version of Raft algorithm, controller performance can be improved. The details of the experiment results are cleary described.

Load Sharing Ratio of Raft in Piled Raft on Granular Soils by Model Test (모형실험에 의한 조립토 지반에 설치된 말뚝지지 전면기초에서 래프트의 하중분담률)

  • Kwon, Ohkyun
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.3
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    • pp.67-75
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    • 2007
  • This study was undertaken in order to investigate the load bearing capacity of raft in a piled raft through the laboratory model tests, the numerical and analytical analyses. The model tests were conducted about a piled raft, the free-standing pile group, a single pile, as well as a shallow foundation under equal conditions. The pile spacing and length, group type and soil conditions were varied in the laboratory model tests. The experimental results were compared with those by the commercial program, DEFPIG, conventional methods and Phung's method. According to this study, the behavior of piled raft was affected by pile spacing, length and soil conditions. Phung's method proved to be reliable for estimating the experimental results.

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Numerical Investigation on Piled Raft Foundation on Sandy Soils (사질토 지반에 시공된 말뚝전면기초의 수치해석연구)

  • Ahn, Tae-Bong
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.6
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    • pp.67-72
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    • 2012
  • Finite element method was used to compare un-piled and piled raft foundation behaviors on sandy soils in this study. The soil parameters were estimated from SPT tests of 25 boreholes. Based on these soil parameters, a finite element analysis was conducted on un-piled and piled raft foundations. For the un-piled raft, the normalized settlement parameter for raft sizes of $8m{\times}8m$ and $15m{\times}15m$ ranged from 1.02~1.15 and 0.64~0.81, respectively. The raft thickness affects differential settlement and bending moments, but has little effect on load sharing or maximum settlement. Pile spacing greatly affected the maximum settlement, the differential settlement, the bending moment in the raft, and the load shared by the piles, while the differential settlement, the maximum bending moment and the load sharing are not affected very much by increasing the pile lengths.

Behavior of piled rafts overlying a tunnel in sandy soil

  • Al-Omari, Raid R.;Al-Azzawi, Adel A.;AlAbbas, Kadhim A.
    • Geomechanics and Engineering
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    • v.10 no.5
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    • pp.599-615
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    • 2016
  • The present research presents experimental and finite element studies to investigate the behavior of piled raft-tunnel system in a sandy soil. In the experimental work, a small scale model was tested in a sand box with load applied vertically to the raft through a hydraulic jack. Five configurations of piles were tested in the laboratory. The effects of pile length (L), number of piles in the group and the clearance distance between pile tip and top of tunnel surface (H) on the load carrying capacity of the piled raft-tunnel system are investigated. The load sharing percent between piles and rafts are included in the load-settlement presentation. The experimental work on piled raft-tunnel system yielded that all piles in the group carry the same fraction of load. The load carrying capacity of the piled raft-tunnel model was increased with increasing (L) for variable (H) distances and decreased with increasing (H) for constant pile lengths. The total load carrying capacity of the piled raft-tunnel model decreases with decreasing number of piles in the group. The total load carrying capacity of the piles relative to the total applied load (piles share) increases with increasing (L) and the number of piles in the group. The increase in (L/H) ratio for variable (H) distance and number of piles leads to an increase in piles share. ANSYS finite element program is used to model and analyze the piled raft-tunnel system. A three dimensional analysis with elastoplastic soil model is carried out. The obtained results revealed that the finite element method and the experimental modeling are rationally agreed.

Piled Raft Foundations (말뚝지지 전면기초)

  • Kwon, Oh-Kyun;Lee, Whoal
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.11a
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    • pp.102-117
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    • 2002
  • The general design practice for piled footings is based on the assumption that the piles are free-standing, and that all the external loads are carried by the piles, with any contribution of the footing being ignored. This approach is not reasonable, because the footing itself is actually in direct contact with the soil, and thus carries a significant fraction of the loads. In the case of not considering the bearing capacity of footing, the bearing capacity of group piles can be evaluated conservatively in the designing the group piles. There are a number of reasons why the idea of piled raft design with considering the capacity of footing has not become widely used. One of the reasons is the lack of reliable calculation methods for estimating the behavior of piled raft. In this study the bearing capacity, settlement, load distribution, etc. of piled raft footing are studied.

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A Study on The Settlement Behavior of Foundations for Light-weight Structures on Clay Deposits (연약지반에서 경량구조물 기초의 침하거동에 관한 연구)

  • Lee, Kwang-Yeol;Chung, Chin-Gyo;Yun, Sung-Tae
    • Proceedings of the Korean Geotechical Society Conference
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    • 2007.09a
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    • pp.692-700
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    • 2007
  • There are several types of foundations for light-weight structures, such as low story buildings, on soft clay deposits. Those foundations, such as piled raft, compensated foundation, mat foundation, floating foundation are commonly used rather then end-bearing piles to get more benefits on the construction and cost savings. In this study, settlement behaviors are computed and compared for several types of foundations on soft clay deposits. Also, theoretical expressions of parameters for piled raft system were provided with co-relations for design purposes. The predictions of settlements of piled rafts foundation are proposed based on the pile dimensions and design loads. From this study, the piled raft foundations is more benefits for reducing the settlement of clay deposits, and it is found that the piled raft system is applicable and effective on thick clay deposits, and that differential settlements of the foundation should be managed by designing the configuration of pile lengths.

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A Study on Interaction Factor of Granular Compaction Piled Raft (조립토 Piled Raft의 상호작용계수에 관한 연구)

  • 신방웅;채현식;김홍택;강인규;박사원
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.269-276
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    • 2000
  • Granular compaction piled raft systems have been effectively used in soft ground foundation to improve not only settlement but also bearing capacity. In the present study, to examine the behavior characteristics and bulging failure zone on granular compaction piled raft system, carbon rod tests have been performed. The test results are compared with the zone of bulging failure and the effects of pile-pile interaction obtained from the analytical approaches. In addition, parametric studies are peformed with considering pile slenderness ratio, Poisson's ratio and load sharing ratio.

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An Effect of Insulated Raft on Longterm Hot Water Storage (Insulated Raft가 장기온수저장에 미치는 영향)

  • Pak, Ee-Tong;Cho, Woon
    • Solar Energy
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    • v.17 no.1
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    • pp.79-91
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    • 1997
  • Thermal energy storage system used a storage tank is a reasonable method to solve energy problem. In thermal energy storage system, energy collected from many types of heat source is stored in a storage tank and then supply to load at the time is in demand. In this study, flow characteristics and storage efficiency were analysed by using a insulated raft in longterm hot water storage system. From the experiment it is found that insulated raft has a important role in longterm hot water storage system and storage efficiency can be obtained to 96% using inletport type and insulated raft together.

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Optimum pile arrangement in piled raft foundation by using simplified settlement analysis and adaptive step-length algorithm

  • Nakanishi, Keiji;Takewaki, Izuru
    • Geomechanics and Engineering
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    • v.5 no.6
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    • pp.519-540
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    • 2013
  • This paper presents an optimal design method for determining pile lengths of piled raft foundations. The foundation settlement is evaluated by taking into account the raft-pile-soil interaction. The analysis of settlement is simplified by using Steinbrenner's equation. Then the total pile length is minimized under the settlement constraint. An extended sequential linear programming technique combined with an adaptive step-length algorithm of pile lengths is used to solve the optimal design problem. The accuracy of the simplified settlement analysis method and the validity of the obtained optimal solution are investigated through the comparison with the actual measurement result in existing piled raft foundations.

A Priority-based Raft Algorithm Used in Distributed Controllers in SDN (SDN 분산 컨트롤러에 사용되는 우선순위 기반 Raft 알고리즘)

  • Yoo, Seung-Eon;Kim, Se-Jun;Kim, Kyung-Tae;Youn, Hee-Young
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2018.01a
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    • pp.9-10
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    • 2018
  • SDN 환경에서 여러 컨트롤러의 동기화는 중요한 문제로 대두되었다. 모든 컨트롤러의 네트워크 상태가 동일한지 여부를 확인하려면 컨트롤러를 효율적으로 동기화하기 위한 합의과정이 필요하다. 하지만 합의 과정에서 일어나는 지도자 선출과정이 임의적이기 때문에 시스템 상에서 시간지연이 일어날 수 있다. 본 논문에서 제안하는 우선순위 기반 Raft 알고리즘은 동기화 프로세스를 제어하는 강력한 지도자를 선택하여 동기화로드에서 시간을 절약할 수 있다.

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