• Title/Summary/Keyword: Balance Capability

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Experiment of Natural Circulation Loop Using a Cryocooler (극저온냉동기를 이용한 자연순환 루프의 실험)

  • Kim, M.J.;Chang, H.M.
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2194-2199
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    • 2007
  • An experimental study is performed to investigate the thermal and flow characteristics of subcooled liquid nitrogen in a natural circulation loop. Experimental apparatus is designed and constructed such that a closed loop is cooled at the top by a cryocooler and heated nearly at the bottom by cartridge heaters. Steady state is obtained by controlling the heating power to the cartridge heaters and a thin-film heater to reduce the cooling power of the cryocooler. Temperature is measured at several locations of the loop and the mass flow rate through the loop is estimated from the energy balance in terms of the measured temperatures. Experiment is repeated for various values of the vertical height between the cooling and heating parts. The results show that the heat transfer capability of the loop has a maximum at a certain value of height. The optimal height to maximize the heat transfer is in a good agreement with analytical prediction to take into account the buoyancy and viscous forces in the loop.

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Balancing the Cubli Frame with LQR-controlled Reaction Wheel (반작용 휠의 LQR 제어를 통한 Cubli 프레임의 균형유지)

  • Kim, Yonghun;Park, Junmo;Han, Seungoh
    • Journal of Sensor Science and Technology
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    • v.27 no.3
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    • pp.165-169
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    • 2018
  • A single-axis Cubli frame realized simply with an IMU sensor and DC motor is presented herein. To maintain the balance on the Cubli frame, an LQR controller based on a Lagrangian derivation of the dynamics was designed, which utilized the state variables of the frame angle and its angular acceleration, as well as the wheel angle and its angular acceleration. The designed LQR controller showed a settling time balancing capability of approximately two seconds and 40% of the maximum overshoot in Matlab/Simulink simulations. Our experimental results of the fabricated Cubli frame matched with the simulation results. It maintained balancing at the reference position even though an initial offset as well as external disturbance during the balancing was applied.

Power System Security Control Method for Quench Characteristic of High-Temperature Superconducting Cable (초전도 케이블의 퀜치 특성에 대한 계통안전성 제어방식)

  • Lee, Geun-Joon;Hwang, Si-Dol;Lee, Jeong-Phil;Kim, Chang-Hyun;Park, Hye-Chul
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2004.11a
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    • pp.375-380
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    • 2004
  • This paper presents the basic quench protection idea for the HTS(High-Temperature Superconducting) cable. In Korea power system, the transfer capability of transmission line is limited by the voltage stability, and HTS cable could be one of the countermeasure to solve the transfer limit as its higher current capacity and lower impedance[1]. However, the quench characteristic of HTS cable makes HTS cable to loss its superconductivity, and therefore change the impedance of the line and power system operating condition dramatically. This pheonominum threats not only HTS cable safety but also power system security, therefore a proper protection scheme and security control counterplan have to be established before HTS cable implementation. In this paper, the quench characteristics of HTS cable for the fault current based on heat balance equation was established and a proper protection method by FCL(Fault Current Limiter) was suggested.

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Effect of Adjustable Speed Pumped Storage Power Generator on the Frequency Control Against the Intermittence of Wind Turbine Output (풍력발전기 출력변동성에 대비한 가변속 양수발전기의 주파수 제어효과)

  • Park, Min-Su;Chun, Yeong-Han
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.3
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    • pp.338-342
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    • 2014
  • Energy storage is a key issue when integrating large amounts of intermittent and non-dispatchable renewable energy sources into electric power systems. To maintain the instantaneous power balance and to compensate for the influence of power fluctuations from renewable sources, flexible capability for power control is needed. Adjustable Speed Pumped Storage Power Generator is pumped storage unit that is adjustable for pump output adjustments as well as the highest efficiency operations because it has fast response time. In this paper we address the adjustable speed pumped storage power generator for frequency control against the intermittence of wind turbine output and calculate the appropriate capacity of adjustable speed pumped storage power generator.

Study on the Performance Ratio of PV System for Capability (용량별 태양광 시스템의 발전 성능에 관한 연구)

  • Park, Jaegyun;Yi, Somi
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.107.2-107.2
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    • 2011
  • 태양광발전 시스템의 성능 평가는 신뢰할 수 있는 데이터의 취득 및 분석을 통하여 발전성능을 제시할 수 있다. 발전성능에 영향을 미치는 요인으로는 일사량과 온도 등의 환경적인 요인, 시스템 구성에 따른 기술적인 요인에 의해 결정될 수 있다. 특히, 시스템 구성에 의해 결정되는 기술적인 요인은 태양전지 모듈의 어레이 손실 및 BOS의 자체 손실 등을 분석하여 전체 시스템의 발전성능을 분석하여 그 성능을 평가할 수 있다. 본 논문에서는 기 설치된 태양광발전 시스템에서 취득된 데이터를 통하여 용량별, 지역별에 따른 태양광발전 시스템의 성능 분석과 손실 원인을 분석하였다. 분석결과 시스템의 성능은 환경적인 요인과 기술적인 요인에 의해 발전성능이 달라진다는 것을 확인할 수 있었다. 본 논문의 결과는 향후 태양광 발전 시스템의 성능의 기준을 제시하는 연구를 위한 사전연구로써 유용한 자료가 되리라 믿는다.

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Wheeled Blimp: Hybrid Structured Airship with Passive Wheel Mechanism for Tele-guidance Applications

  • Kang, Sung-Chul;Nam, Mi-Hee;Kim, Bong-Seok
    • Journal of Mechanical Science and Technology
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    • v.18 no.11
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    • pp.1941-1948
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    • 2004
  • This paper presents a novel design of indoor airship having a passive wheeled mechanism and its stationary position control. This wheeled blimp can work both on the ground using wheeled vehicle part and in the air using the floating capability of the blimp part. The wheeled blimp stands on the floor keeping its balance using a caster-like passive wheel mechanism. In tele-guidance application, stationary position control is required to make the wheeled blimp naturally communicate with people in standing phase since the stationary blimp system responds sensitively to air flow even in indoor environments. To control the desired stationary position, a computed torque control method is adopted. By performing a controller design through dynamic analysis, the control characteristics of the wheeled blimp system have been found and finally the stable control system has been successfully developed. The effectiveness of the controller is verified by experiment for the real wheeled blimp system.

Modeling of Turbulent Molecular Mixing by the PDF Balance Method for Turbulent Reactive Flows (난류연소 유동장에서의 확률밀도함수 전달방정식을 이용한 난류혼합 모델링)

  • Moon, Hee-Jang
    • Journal of the Korean Society of Combustion
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    • v.2 no.1
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    • pp.39-51
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    • 1997
  • A review of probability density function(PDF) methodology and direct numerical simulation for the purpose of modeling turbulent combustion are presented in this study where particular attention is focused on the modeling problem of turbulent molecular mixing term appearing in PDF transport equation. Existing mixing models results were compared to those evaluated by direct numerical simulation in a turbulent premixed medium with finite rate chemistry in which the initial scalar field is composed of pockets of partially burnt gases to simulate autoignition. Two traditional mixing models, the least mean square estimations(LMSE) and Curl#s model are examined to see their prediction capability as well as their modeling approach. Test calculations report that the stochastically based Curl#s approach, though qualitatively demonstrates some unphysical behaviors, predicts scalar evolutions which are found to be in good agreement with statistical data of direct numerical simulation.

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TRAJECTORY CONTROL OF ROBOT MANIPULATORS USING VSS THEDORY smoothing modification : SMOOTHING MODIFICATION

  • Hideki Hashimoto;Sim, Kwee-Bo;Jianxin Xu;F. Harashima
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10a
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    • pp.898-904
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    • 1987
  • A new control algorithm using the VSS theory is developed for accurate trajectory control of robot manipulators. This paper focuses on the implementation of VSS controller with smoothing laws in the design of effective tracking control for robotic arms. The VSS controller for multi-linkage robot arm is realized using balance condition and its simplification which possesses powerful smoothing capability to reduce or even remove undesirable chattering and meanwhile keep the robust characteristic to reject system uncertainties. The design principle of selecting different smoothing methods, which aims at achieving trade-off between smoothing and robust behaviors while considering the actual system constraints, is also given and further confirmed through experimental results.

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Intelligent Walking Modeling of Humanoid Robot Using Learning Based Neuro-Fuzzy System (학습기반 뉴로-퍼지 시스템을 이용한 휴머노이드 로봇의 지능보행 모델링)

  • Park, Gwi-Tae;Kim, Dong-Won
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.4
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    • pp.358-364
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    • 2007
  • Intelligent walking modeling of humanoid robot using learning based neuro-fuzzy system is presented in this paper. Walking pattern, trajectory of the zero moment point (ZMP) in a humanoid robot is used as an important criterion for the balance of the walking robots but its complex dynamics makes robot control difficult. In addition, it is difficult to generate stable and natural walking motion for a robot. To handle these difficulties and explain empirical laws of the humanoid robot, we are modeling practical humanoid robot using neuro-fuzzy system based on the two types of natural motions which are walking trajectories on a t1at floor and on an ascent. Learning based neuro-fuzzy system employed has good learning capability and computational performance. The results from neuro-fuzzy system are compared with previous approach.

Mass Standards Calibration through Internet (인터넷을 이용한 표준분동 교정 활용)

  • 이우갑;정진완;김광표
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1109-1112
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    • 2003
  • Information technology has enabled mass standards calibration to be performed through internet. For this, an automatic weight handler was manufactured. During the operation the images of weight operation and the system are provided via the measurement system and a web server. The measurement system consists of a balance, a weight handler, instruments for environment measurement and a PC. The weight handler automatically loads and unloads weights on and from the weighing pan. The weight handler allows 6 series weights to be operated for weight calibration of 100-50-20-20-10-10 gram series weight. This capability could be used for "remote training" for series weight calibration.

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