• Title/Summary/Keyword: load-balanced

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An Influence of Groundwater Flow on Performance of Closed Borehole Heat Exchangers (Part-2) (지하수류가 밀폐형 천공 지중 열교환기 성능에 미치는 영향(2))

  • Hahn, Jeongsang;Kiem, Youngseek;Lee, Juhyun;Lee, Byoungho;Hahn, Chan
    • Journal of Soil and Groundwater Environment
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    • v.21 no.6
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    • pp.114-127
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    • 2016
  • An increase of groundwater flux in BHE system creates that ground temperature (locT) becomes lower in summer and higher in winter time. In other words, it improves significantly the performance of BHE system. The size of thermal plume made up by advection driven-flow under the balanced energy load is relatively small in contrast to the unbalanced energy load where groundwater flow causes considerable change in the size of thermal plume as well ground temperature. The ground temperatures of the up gradient and down gradient BHEs under conduction only heat transport are same due to no groundwater flow. But a significant difference of the ground temperature is observed between the down gradient and up gradient BHE as a result of groundwater flow-driven thermal interference took placed in BHE field. As many BHEs are designed under the obscure assumption of negligible groundwater flow, failure to account for advection can cause inefficiencies in system design and operation. Therefore including groundwater flow in the design procedure is considered to be essential for thermal and economic sustain ability of the BHE system.

Performance Analysis of Load Balanced Metadata Catalog Service (부하분산 메타데이터 카탈로그 서비스의 성능 분석)

  • Ahn, Sunil;Lee, Sehoon;Kim, Namgyu;Hwang, Soonwook
    • Proceedings of the Korea Contents Association Conference
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    • 2007.11a
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    • pp.555-559
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    • 2007
  • AMGA is a metadata catalogue service which offers access to metadata for files stored on the Grid. We evaluated the performance of AMGA and analyzed overhead in the current AMGA implementation. It had 700% poor throughput (read/insert per second) compared with the direct DB access. The biggest overhead was in managing GSI/SSL Connections, degrading throughput about 350%. We alsomeasured the throughput of load-balanced AMGA services, and it showed linear throughput improvement when we increased the number of AMGA server. In addition, we measured the throughputin the WAN environment, and it showed the number of the maximum connections that an AMGA server can handle is the most critical factor in the throughput.

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A Symmetric Carrier Technique of CRPWM for Voltage Balance Method of the Flying Capacitor Multi-level Inverter (플라잉 커패시터 멀티-레벨 인버터의 커패시터 전압 균형을 이루기 위한 캐리어 비교방식의 대칭 기법)

  • 전재현;김태진;강대욱;현동석
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.12
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    • pp.624-631
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    • 2003
  • This paper presents a simple carrier symmetric method for the voltage balance of flying capacitors in FCMLI(flying capacitor multi-level inverter). To achieve the voltage balance of flying capacitors, the utilization of each carrier must be balanced during a half-cycle of the switching period such as PSPWM(Phase-Shifted PWM). However, the CRPWM(Carrier Redistribution PWM) method causes the fluctuation of flying capacitor voltages because the balanced utilization of carriers is not achieved. Moreover, it does not consider that the load current change has an influence on flying capacitor voltages by assuming that the current flows into the load. To overcome the drawbacks of CRPWM, it is modified by the technique that carriers of each band are disposed symmetrically at every fundamental period. Firstly, the CRPWM method is reviewed and the theory on voltage balance of flying capacitors is analyzed. The proposed method is introduced and is verified through the experiment result.

A Symmetric Carrier Technique of CRPWM for Voltage Balance Method of the Flying Capacitor Multi-level Iinverter (플라잉 커패시터 멀티-레벨 인버터의 커패시터 전압 균형을 이루기 위한 캐리어 비교방식을 이용한 캐리어 대칭 기법)

  • Jeon J.H.;Kim T.J.;Kang D.W.;Hyun D.S.
    • Proceedings of the KIPE Conference
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    • 2003.07b
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    • pp.606-610
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    • 2003
  • This paper presents a simple carrier symmetric method for the voltage balance of flying capacitors in FCMLI(flying capacitor multi-level inverter). To achieve the voltage balance of flying capacitors, the utilization of each carrier must be balanced during a half-cycle of the switching period such as PSPWM(Phase-Shifted PWM). However, the CRPWM(Carrier Redistribution PWM) method causes the fluctuation of flying capacitor voltages because the balanced utilization of carriers is not achieved. Moreover, it does not consider that the load current change has an influence on flying capacitor voltages by assuming that the current flows Into the load. To overcome the drawbacks of CRPWM, it is modified by the technique that carriers of each band are disposed symmetrically at every fundamental period. Firstly, the CRPWN method is reviewed and the theory on voltage balance of flying capacitors is analyzed. The proposed method Is introduced and is verified through the experiment result.

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Flexural behavior of ultra high performance concrete beams reinforced with high strength steel

  • Wang, Jun-Yan;Gu, Jin-Ben;Liu, Chao;Huang, Yu-Hao;Xiao, Ru-Cheng;Ma, Biao
    • Structural Engineering and Mechanics
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    • v.81 no.5
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    • pp.539-550
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    • 2022
  • A detailed experimental program was conducted to investigate the flexural behavior of ultra high performance concrete (UHPC) beams reinforced with high strength steel (HSS) rebars with a specified yield strength of 600 MPa via direct tensile test and monotonic four-point bending test. First, two sets of direct tensile test specimens, with the same reinforcement ratio but different yield strength of reinforcement, were fabricated and tested. Subsequently, six simply supported beams, including two plain UHPC beams and four reinforced UHPC beams, were prepared and tested under four-point bending load. The results showed that the balanced-reinforced UHPC beams reinforced with HSS rebars could improve the ultimate load-bearing capacity, deformation capacity, ductility properties, etc. more effectively owing to interaction between high strength of HSS rebar and strain-hardening characteristic of UHPC. In addition, the UHPC with steel rebars kept strain compatibility prior to the yielding of the steel rebar, further satisfied the plane-section assumption. Most importantly, the crack pattern of the UHPC beam reinforced with HSS rebars was prone to transform from single main crack failure corresponding to the normal-strength steel, to multiple main cracks failure under the condition of balanced-reinforced failure, which validated by the conclusion of direct tensile tests cooperated with acoustic emission (AE) source locating technique as well.

Load Balanced Volume Rendering System for Concurrent Users in Multi-CPU Server Environment (다중 CPU 서버 환경에서 동시 사용자를 위한 부하조절 기반 볼륨 가시화 시스템)

  • Lee, Woongkyu;Kye, Heewon
    • Journal of Korea Multimedia Society
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    • v.18 no.5
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    • pp.620-630
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    • 2015
  • This research suggests a load balancing method for a volume rendering system which supports concurrent users. When concurrent users use a volume rendering server system, the computational resources are occupied by a particular user by turns because each process consumes the computational resources as much as possible. In this case, the previous method shows acceptable throughput but the latency is increased for each user. In this research, we suggest a method to improve the latency without performance degradation. Each process makes concessions for taking the resources according to the number of users connected to the system. And we propose a load balancing method in the dynamic situation in which the number of users can vary. Using our methods, we can improve the latency time for each user.

A Load Balancing Model for Improving Performance of Web-Based Information System (웹 정보시스템의 서비스 성능 향상을 위한 부하균형 모델 제안)

  • Kim, Su-Jeong;Baek, Seung-Gu;Kim, Jong-Geun
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.11S
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    • pp.3179-3189
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    • 1999
  • In this paper, different methods of integrating heterogeneous network information systems into the Web are observed by comparing a cliented Java CGI model with a server-oriented CGI model. In addition, a load balanced(LB, for short) CGI model is proposed, which combines two models and decides its course of action depending on the load state of the web server, and compared with the other two models. Performance evaluation models for three models are also presented. The results of computer simulations indicate that the LB CGI model performs consistently well irrespective of system load or server performance.

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A STUDY ON THE REACTIVE POWER COMPENSATION OF THREE PHASE UNBALANCED LOAD FOR VAR SYSTEM (VAR 시스템에 의한 3 상 불평형 부하의 무효전력 보상에 관한 연구)

  • Jung, Yon-Taek;Seo, Young-Soo;Kim, Young-Bong;Kim, Han-Soo;Lee, Bong-Joo
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.531-534
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    • 1989
  • In this paper, the way that input voltage and input line current as a control variable is provided as one unit is projected. Till no, have denied with three phase balanced load. But, in that case, total power factor compensation is difficult, for to control each phase at unbalanced load. Therefor, in this paper suggest of the scheme that three phase unbalanced load is controlled by each phase and input total power factor is compensated unit input factor. therefore, in this paper suggest that three phase unbalanced load is controlled and the method in compensation of unit input factor to be attended by unbalanced load. Besides, the object of control is calculating quantity for input voltage and input line current for the point at issuse make to improve of control method at unbalanced load. As a result, control system of each phase could maintain as a unit input total power factor has been state diviation error of 2% with unbalanced load.

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Croup Load Balancing Algorithm Using State Information Inference in Distributed System (분산시스템에서 상태 정보 추론을 이용한 그룹 부하 균등 알고리즘)

  • 정진섭;이재완
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.8
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    • pp.1259-1268
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    • 2002
  • One of the major goals suggested in distributed system is to improve the performance of the system through the load balancing of whole system. Load balancing among systems improves the rate of processor utilization and reduces the turnaround time of system. In this paper, we design the rule of decision-making and information interchange based on knowledge based mechanism which makes optimal load balancing by sharing the future load state information inferred from past and present information of each nodes. The result of performance evaluation shows that utilization of processors is balanced, the processing time is improved and reliability and availability of systems are enhanced. The proposed mechanism in this paper can be utilized in the design of load balancing algorithm in distributed operating systems.

An Output Voltage Balance Control of Grid Connected Inverter by Phase Current Control at Critical Load Unbalanced Condition (계통연계 인버터의 주요 부하 불평형 시 상전류 제어를 통한 부하 상전압 평형 제어)

  • Tae-Hyeon Park;Hag-Wone Kim;Kwan-Yuhl Cho;Joon-Ki Min;Won-Il Choi
    • The Transactions of the Korean Institute of Power Electronics
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    • v.28 no.1
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    • pp.22-29
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    • 2023
  • A grid-connected inverter can be used in grid-connected or stand-alone modes. Generally, a grid-connected inverter operates in a grid-connected mode, but the inverter operates in stand-alone mode if grid faults occur. In the stand-alone mode, the grid-connected inverter must supply electric power to a critical load that needs to receive stable power even though grid faults occur. Generally, three-phase loads are used as critical loads, but a single phase is configured in some cases. In these conditions, the critical load is required to unbalance the load power consumption, which makes the three-phase load voltage unbalancd. This unbalanced voltage problem can cause fatal problems to the three-phase critical loads, and thus must be addressed. Hence, this paper proposes an algorithm to solve this unbalanced voltage problem by the individual phase current control. The proposed method is verified using Psim simulation and experiments.