• Title/Summary/Keyword: Loop space

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Modeling of Grade Change Operations in Paper Mills

  • Ko, Jun-Seok;Yeo, Yeong-Koo;Ha, Seong-Mun;Lim, Jung-Woo;Ko, Du-Seok;Hong Kang
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.35 no.5
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    • pp.46-52
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    • 2003

  • In this work we developed the closed-loop model of a paper machine during grade change with the intention to provide a reliable dynamic model to be used in the model-based grade change control scheme. During the grade change, chemical and physical characteristics of paper process change with time. It is very difficult to represent these characteristics on-line by using physical process models. In this work, the wet circulation part and the drying section were considered as a single process and closed-loop identification technique was used to develop the grade change model. Comparison of the results of numerical simulations with mill operation data demonstrates the effectiveness of the model identified.

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A Unifying Design of $H_\infty$ Controller with PI Xpeed Feedback for High Precision Position Control of Flexible System

  • Chun, Yeonghan;Hori, Yoichi
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.553-557
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    • 1994

  • We propose a design method that uses H$_{\infty}$ optimization method to suppress oscillation of a shaft between motor and load for high precision (0.001 % of reference input) position controls. PI speed control loop was introduced as a minor loop. Standard problem is used for the modeling of the system and Glover-Doyle's algorithm is used for the optimization in the H$_{\infty}$ space. Friction is considered to be an important factor that makes it difficult for the system to reach steady state in short time. In this paper, we propose a hybrid controller that includes PI speed feedback loop, which is expected to have a role to reject torque disturbance like friction.n.n.

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ORIGINS OF THE FLOW AND MAGNETIC STRUCTURE INVOLVED IN THE FORMATION AND ERUPTION OF A SOLAR PROMINENCE

  • Magara, Tetsuya
    • Journal of The Korean Astronomical Society
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    • v.54 no.5
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    • pp.157-170
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    • 2021

  • We investigate flow and magnetic structure of a solar prominence with a focus on how the magnetic field originally determined by subsurface dynamics gives rise to the structure. We perform a magnetohydrodynamic simulation that reproduces the self-consistent evolution of a flow and the magnetic field passing freely through the solar surface. By analyzing Lagrangian displacements of magnetized plasma elements, we demonstrate the flow structure that is naturally incorporated to the magnetic structure of the prominence formed via dynamic interaction between the flow and the magnetic field. Our results explain a diverging flow on a U-loop, a counterclockwise downdraft along a rotating field line, acceleration and deceleration of a downflow along an S-loop, and partial emergence of a W-loop, which may play key roles in determining structural properties of the prominence.

  • https://doi.org/10.5303/JKAS.2021.54.5.157 인용 PDF KSCI

An approach to the coupled dynamics of small lead cooled fast reactors

  • Zarei, M.
    • Nuclear Engineering and Technology
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    • v.51 no.5
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    • pp.1272-1278
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    • 2019

  • A lumped kinetic modeling platform is developed to investigate the coupled nuclear/thermo-fluid features of the closed natural circulation loop in a low power lead cooled fast reactor. This coolant material serves a reliable choice with noticeable thermo-physical safety characteristics in terms of natural convection. Boussienesq approximation is resorted to appropriately reduce the governing partial differential equations (PDEs) for the fluid flow into a set of ordinary differential equations (ODEs). As a main contributing step, the coolant circulation speed is accordingly correlated to the loop operational power and temperature levels. Further temporal analysis and control synthesis activities may thus be carried out within a more consistent state space framework. Nyquist stability criterion is thereafter employed to carry out a sensitivity analysis for the system stability at various power and heat sink temperature levels and results confirm a widely stable natural circulation loop.

  • https://doi.org/10.1016/j.net.2019.03.015 인용 PDF KSCI

Does Second-Generation Suspensory Implant Negate Tunnel Widening of First-Generation Implant Following Anterior Cruciate Ligament Reconstruction?

  • Sundararajan, Silvampatti Ramasamy;Sambandam, Balaji;Singh, Ajay;Rajagopalakrishnan, Ramakanth;Rajasekaran, Shanmuganathan
    • Knee surgery & related research
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    • v.30 no.4
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    • pp.341-347
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    • 2018

  • Purpose: Tunnel widening following anterior cruciate ligament (ACL) reconstruction is commonly observed. Graft micromotion is an important contributing factor. Unlike fixed-loop devices that require a turning space, adjustable-loop devices fit the graft snugly in the tunnel. The purpose of this study is to compare tunnel widening between these devices. Our hypothesis is that the adjustable-loop device will create lesser tunnel widening. Materials and Methods: Ninety-eight patients underwent ACL reconstruction from January 2013 to December 2014. An adjustable-loop device was used in 54 patients (group 1) and a fixed-loop device was used in 44 patients (group 2). Maximum tunnel widening at 1 year was measured by the L'Insalata's method. Functional outcome was measured at 2-year follow-up. Results: The mean widening was 4.37 mm (standard deviation [SD], 2.01) in group 1 and 4.09 mm (SD, 1.98) in group 2 (p=0.511). The average International Knee Documentation Committee score was 78.40 (SD, 9.99) in group 1 and 77.11 (SD, 12.31) in group 2 (p=0.563). The average Tegner-Lysholm score was 87.25 (SD, 3.97) in group 1 and 87.29 in group 2 (SD, 4.36) (p=0.987). There was no significant difference in tunnel widening and functional outcome between the groups. Conclusions: The adjustable-loop device did not decrease the amount of tunnel widening when compared to the fixed-loop device. There was no significant difference in outcome between the two fixation devices. Level of Evidence: Level 3, Retrospective Cohort.

  • https://doi.org/10.5792/ksrr.18.005 인용

Global features of the Cygnus Loop observed with FIMS

  • Seon Kwang-Il;Park Jang-Hyun;Lee Dae-Hee;Jin Ho;Yuk In-Soo;Han Wonyong;Nam Uk-Won;Kim Il-Joong;Shinn Jong-Ho;Ryu Kwang-Sun;Min Kyung W.;Edelstein Jerry;Korpela Erick
    • The Bulletin of The Korean Astronomical Society
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    • v.30 no.1
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    • pp.32.1-32.1
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    • 2005

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A Study on the Optimized Architectural Space Planning by Searching Algorithm Method (탐색적 방법에 의한 건축공간 배치계획 최적화에 대한 고찰)

  • Lim, Myung-Gu;Kim, Su-Young
    • Journal of The Korean Digital Architecture Interior Association
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    • v.1 no.1
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    • pp.51-58
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    • 2001

  • The purpose of this study is to improve productivity of architectural space planning(A.S.P,) by computer system and to optimize ASP. A searching algorithm is the best way to slave optimized A.S.P. Because architectural design is too many various site situations and client's demands to specify the general solving methods. This method seek the best design case in all possibility and to be modeled as this; $\rightarrow$[$\rightarrow$$\rightarrow$