• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2008.05a
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• pp.73-73
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• 2008

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2008.05a
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• pp.74-74
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• 2008

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2007.10a
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• pp.574-574
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• 2007

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2007.10a
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• pp.626-626
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• 2007

• Journal of Power Electronics
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• v.18 no.2
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• pp.467-481
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• 2018

Modular multilevel converter (MMC)-based high-voltage direct current (HVDC) presents attractive technical advantages and contributes to enhanced system operation and reduced oscillation damping in dynamic MMC-HVDC systems. We propose an advanced small-signal multi-terminal MMC-HVDC based on dynamic phasors and state space for power system stability analysis to enhance computational accuracy and reduce simulation time. In accordance with active and passive network control strategies for multi-terminal MMC-HVDC, the matchable small-signal stability models containing high harmonics and dynamics of internal variables are conducted, and a related theoretical derivation is carried out. The proposed advanced small-signal model is then compared with electromagnetic-transient and traditional small-signal state-space models by adopting a typical multi-terminal MMC-HVDC network with offshore wind generation. Simulation indicates that the advanced small-signal model can successfully follow the electromechanical transient response with small errors and can predict the damped oscillations. The validity and applicability of the proposed model are effectively confirmed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.40-47
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• 2017

In this paper, a small signal model for grid-connected inverter with unipolar pulse width modulation method is presented. Small-signal analysis allows to predict the stability and dynamics of the inverter. To regulate output voltage and to achieve power factor correction, inverter has two control loops. Loop gains are useful to identify the stability for multi-loop controlled system. Based on small-signal model, controllers are designed to improve audio susceptibility and output impedance characteristics. Proposed small-signal model and controllers are verified by PSIM simulation and experiments.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2007.05a
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• pp.99-99
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• 2007

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2007.05a
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• pp.120-120
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• 2007

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.851-859
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• 2021

Small PWR can be used for power generation and heating. Considering that small PWR has the characteristics of flexible operating conditions and complex operating environment, the controller designed based on single power level is difficult to achieve the ideal control of small PWR in the whole range of core power range. To solve this problem, a flexible switching controller based on fuzzy controller and LQG/LTR controller is designed. Firstly, a core fuzzy multi-model suitable for full power range is established. Then, T-S fuzzy rules are designed to realize the flexible switching between fuzzy controller and LQG/LTR controller. Finally, based on the core power feedback principle, the core flexible switching control system of small PWR is established and simulated. The results show that the flexible switching controller can effectively control the core power of small PWR and the control effect has the advantages of both fuzzy controller and LQG/LTR controller.

• Journal of the Korean Institute of Educational Facilities
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• v.20 no.6
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• pp.11-20
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• 2013

According to the decrease in birth rate and reduction of population, many schools in rural area have brought about the r decrease of number of student, and environment of education have became deteriorated. Accordingly, small schools be required improvement, and it should be altered placement of schools because it change number of student, distance and time of attending school, and formation of school zone are changed by alternating of human and physical environment. Merger and abolition of small schools are inevitable for change of placement standard to school and qualitative improvement of environment of education in rural area. This study researches the user's satisfaction at the boarding middle school following the merge and abolition of small schools in rural area. Finally, it reports the results of satisfaction research: the users are generally satisfied with education and student school life in the unified dormitory school.