• Title/Summary/Keyword: Dynamic Strategy

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Study on the Characteristic of Dynamic Postural Control during Horizontal Translation of Support Surface (지지면의 수평 진동에 따른 동적 자세 제어 특성에 관한 연구)

  • Oh, G.Y.;Piao, Y.J.;Kwon, T.K.;Kim, N.G.
    • Journal of Biomedical Engineering Research
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    • v.30 no.6
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    • pp.495-502
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    • 2009
  • This paper investigated the effects of dynamic postural control for maintaining upright standing on a support surface during continuous sinusoidal horizontal translation in anterior-posterior direction. 15 healthy young subjects participated in this experiment. The analysis of body movement was analyzed using Ariel Performance Analysis System. Motion pattern was analyzed by seven markers on subject's body. Position of markers were head, chest, hip, right knee, left knee, right ankle and left ankle. Seven different frequencies of support surface were employed ; 0.1, 0.25, 0.5, 0.75, 1, 1.5 and 2Hz at 2cm of moving path of motionbase. The experiments were performed dynamic postural reponses at the condition of eye open. The results showed that median frequency of the knee, ankle were increased in all frequency bands. Following the frequency of perturbation increased, postural control strategy was changed from ankle strategy to combined strategy. The experiment results could be applied to the dynamic postural training for the elderly and the rehabilitation training for the patients to improving the ability of postural control.

An Improved Generation Maintenance Strategy Analysis in Competitive Electricity Markets Using Non-Cooperative Dynamic Game Theory (비협조 동적게임이론을 이용한 경쟁적 전력시장의 발전기 보수계획 전략 분석)

  • 김진호;박종배;김발호
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.9
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    • pp.542-549
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    • 2003
  • In this paper, a novel approach to generator maintenance scheduling strategy in competitive electricity markets based on non-cooperative dynamic game theory is presented. The main contribution of this study can be considered to develop a game-theoretic framework for analyzing strategic behaviors of generating companies (Gencos) from the standpoints of the generator maintenance-scheduling problem (GMP) game. To obtain the equilibrium solution for the GMP game, the GMP problem is formulated as a dynamic non-cooperative game with complete information. In the proposed game, the players correspond to the profit-maximizing individual Gencos, and the payoff of each player is defined as the profits from the energy market. The optimal maintenance schedule is defined by subgame perfect equilibrium of the game. Numerical results for two-Genco system by both proposed method and conventional one are used to demonstrate that 1) the proposed framework can be successfully applied in analyzing the strategic behaviors of each Genco in changed markets and 2) both methods show considerably different results in terms of market stability or system reliability. The result indicates that generator maintenance scheduling strategy is one of the crucial strategic decision-makings whereby Gencos can maximize their profits in a competitive market environment.

Performance Evaluation of Hash Join Algorithms Supporting Dynamic Load Balancing for a Database Sharing System (데이타베이스 공유 시스템에서 동적 부하분산을 지원하는 해쉬 조인 알고리즘들의 성능 평가)

  • Moon, Ae-Kyung;Cho, Haeng-Rae
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.12
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    • pp.3456-3468
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    • 1999
  • Most of previous parallel join algorithms assume a database partition system(DPS), where each database partition is owned by a single processing node. While the DPS is novel in the sense that it can interconnect a large number of nodes and support a geographically distributed environment, it may suffer from poor facility for load balancing and system availability compared to the database sharing system(DSS). In this paper, we propose a dynamic load balancing strategy by exploiting the characteristics of the DSS, and then extend the conventional hash join algorithms to the DSS by using the dynamic load balancing strategy. With simulation studies under a wide variety of system configurations and database workloads, we analyze the effects of the dynamic load balancing strategy and differences in the performances of hash join algorithms in the DSS.

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Synchronous PI Decoupling Control Scheme for DVR against a Voltage Sag in the Power System

  • Kim, Myung-Bok;Lee, Seung-Hoon;Moon, Gun-Woo;Youn, Myung-Joong
    • Journal of Power Electronics
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    • v.4 no.3
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    • pp.180-187
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    • 2004
  • This paper proposes a new control strategy for the dynamic voltage restorer (DVR). It is based on a synchronous PI decoupling control strategy which features fast response time and low steady state error. Therefore, the proposed control strategy produces faster action time against voltage sag and guarantees more than enough compensation for reduced supply voltage. Experimental results, implemented with the TMS320C3${\times}$DSP control unit, are shown to validate the effectiveness of the proposed control strategy.

A Novel Efficiency Optimization Strategy of IPMSM for Pump Applications

  • Zhou, Guangxu;Ahn, Jin-Woo
    • Journal of Electrical Engineering and Technology
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    • v.4 no.4
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    • pp.515-520
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    • 2009
  • According to the operating characteristics of pump applications, they should exhibit high efficiency and energy saving capabilities throughout the whole operating process. A novel efficiency optimization control strategy is presented here to meet the high efficiency demand of a variable speed Permanent Magnet Synchronous Motor (PMSM). The core of this strategy is the excellent integration of mended maximum torque to the current control algorithm, based on the losses model during the dynamic and the grade search method with changed step by fuzzy logic during the steady. The performance experiments for the control system of a variable speed high efficiency PMSM have been completed. The test results verified that the system can reliably operate with a different control strategy during dynamic and steady operation, and the system exhibits better performance when using the efficiency-optimization control.

A Control Strategy for Flywheel Energy Storage / Recovery System with Induction Machine (유도기를 이용한 플라이휠 에너지 저장 및 재생 시스템 제어 기법)

  • Son Jang-Kyung;Lee Hong-Hee;Nho Eui-Cheol;Kim Heung-Gun;Chun Tae-Won
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.5
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    • pp.494-500
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    • 2005
  • The paper proposed a control strategy for flywheel energy/recovery system with induction machine at the dynamic UPS system using the flywheel stored mechanical energy. The performances for the vector controlled induction generator are compared with those for the induction generator using slip control method. The strategy to improve the transient responses for dc link capacitor voltage is suggested at the transition from the motoring mode to the generating mode. The strategy Proposed by the paper is verified with experiment results using 32bit DSP.

A Dynamic Power Distribution Strategy for Large-scale Cascaded Photovoltaic Systems

  • Wang, Kangan;Wu, Xiaojie;Deng, Fujin;Liu, Feng
    • Journal of Power Electronics
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    • v.17 no.5
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    • pp.1317-1326
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    • 2017
  • The cascaded H-bridge (CHB) multilevel converter is a promising topology for large-scale photovoltaic (PV) systems. The output voltage over-modulation derived by the inter-module active power imbalance is one of the key issues for CHB PV systems. This paper proposed a dynamic power distribution strategy to eliminate the over-modulation in a CHB PV system by suitably redistributing the reactive power among the inverter modules of the CHB PV system. The proposed strategy can effectively extend the operating region of the CHB PV system with a simple control algorithm and easy implementation. Simulation and experimental results carried out on a seven-level CHB grid-connected PV system are shown to validate the proposed strategy.

PREREQUISITE OF SUPERIOR PERFORMANCE : MANAGING COALIGNMENT IN A DYNAMIC CONDITION

  • Yoo, Jae-Wook;Seong, Byeong-Chan
    • Management & Information Systems Review
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    • v.25
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    • pp.35-55
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    • 2008
  • We draw on well-established thinking in the complementary fields of organization theory and strategic management to develop a model explaining why fit among a firm's competitive strategy, its structure, and its technology is a prerequisite for superior performance. The contributions of this theoretical treatise are twofold. Firstly, it helps reduce the disconnect in thinking that exists between the strategy and organization-theory literatures on business-level issues. Secondly, it reveals the importance of managing the coalignment among strategy, structure, and technology which, in turn, forces recognition that competitive advantage does not exist in a static state but in a dynamic condition.

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Knowledge-driven Dynamic Capability and Organizational Alignment: A Revelatory Historical Case

  • Kim, Gyeung-Min
    • Asia pacific journal of information systems
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    • v.20 no.1
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    • pp.33-56
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    • 2010
  • The current business environment has been characterized as less munificent, highly uncertain and constantly evolving. In this environment, the company with dynamic capability is reported to be more successful than others in building competitive advantage. Dynamic capability focuses on the link between a dynamically changing environment, strategic agility, architectural reconfiguration, and value creation. Being characterized to be flexible and adaptive to market circumstance changes, an organization with dynamic capability is described to have high resource fluidity, which represents business process, resource allocation, human resource management and incentives that make business transformation faster and easier. Successful redeployment of the resources for dynamic adaptation requires organizational forms and reward systems to be well aligned with firm's technological infrastructures and business process. The alignment is considered to be an executive level commitment. Building dynamic capability is knowledge driven; relying on new knowledge to reconfigure firm's resources. Past studies established the link between the effective execution of a knowledge-focused strategy and relevant setting of architectural elements such as human resources, structure, process and information systems. They do not, however, describe in detail the underlying processes by which architectural elements are adjusted in coordinated manners to build knowledge-driven dynamic capability. In fact, understandings of these processes are one of the top issues in IT management. This study analyzed how a Korean corporation with a knowledge-focused strategy aligned its architectural elements to develop the dynamic capability and thus create value in the dynamically changing markets. When the Korean economy was in crisis, the company implemented a knowledge-focused strategy, restructured the organization's architecture by which human and knowledge resources are identified, structured, integrated and coordinated to identify and seize market opportunity. Specifically, the following architectural elements were reconfigured: human resource, decision rights, reward and evaluation systems, process, and IT infrastructure. As indicated by sales growth, the reconfiguration helped the company create value under an extremely turbulent environment. According to Ancona et al. (2001), depending on the types of lenses the organization uses, different types of architecture will emerge. For example, if an organization uses political lenses focusing on power, influence, and conflict. the architecture that leverage power and negotiate across multiple interest groups would emerge. Similarly, if an organization uses economic lenses focusing on the rational behavior of organizational actors making choices based on the costs and benefits of action, organizational architecture should be designed to motivate and provide incentives for the actors (Smith, 2001). Compared to this view, information processing perspectives consider architecture to be designed to maximize the capacity of information processing by the actors. Using knowledge lenses, the company studied in this research established architectural elements in a manner that allows the firm to effectively structure knowledge resources to form dynamic capability. This study is revelatory single case with a historic perspective. As a result of this study, a set of propositions and a framework are derived, which can be used for architectural alignment.

MINNs for FE model updating of a steel box girder bridge (강박스 거더교의 FE 모델 개선을 위한 평균값 반복 신경망)

  • Vu, Thuy Dung;Cui, Jintao;Kim, Doo-Kie;Koo, Ki-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2011.04a
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    • pp.57-60
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    • 2011
  • Updating model parameters are required in order to simulate the actual behavior of the dynamic structure. A new strategy, mean-iterative neural networks (MINNs) has been proposed in this paper for model parameter updating of a steel box girder bridge. With new strategy for structural dynamic model updating, it offers many advantages such as potential savings of computational effort, more consistent in reaching convergence. The dynamic response obtained from the experimental test on a two span continuous bridge is used as the target for model updating. And the presented algorithm is applied to update the model parameters. These results show a good possible of using MINNs in practice for dynamic model updating.

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