• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.913-919
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• 2005

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modem version supersonic jet fighter aircraft. The flight control system utilizes RSS criteria in both longitudinal and lateral-directional axes to achieve performance enhancements and improve stability. Standard CLDA (Control Law Design and Analysis) process is provided that reduce the development period of the flight control system. In addition, if this process is employed in developing flight control laws, it reduces the trial and error development and verification of control laws. This paper details the design process of developing a flight control law for the RSS aircraft, utilizing military specifications, linear and nonlinea, analysis using XMATH and ATLAS(Aircraft, Tim Linear and Simulation), handling quality tests using the HQS (Handling Quality Simulator), and real flight test results to verify aircraft dynamic flight responses.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1175-1182
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• 1999

This paper shows that a well-defined energy function can be developed to reflect the transfer conductances for multi-machine power systems under an assumption that all transmission lines have uniform R/X rations. The energy function is derived by introducing a pure reactive equivalent system for the given system. In this study, a static energy function reflecting transfer conductances is also derived as well as the transient energy function. The proposed static energy function is applied to voltage stability analysis and tested for various sample systems. The test results show that the accuracy of voltage stability analysis can be considerable improved by reflecting transfer conductances into the energy function.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.90-92
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• 2002

The SVC(Static Var Compensator) resulted from the FACTS technology can generate or absorb reactive power rapidly so as to increase the transient and voltage stability. In this paper, the SVC is applied to the power system in order to improve the total transfer capability from a viewpoint of static voltage stability and the effects of application of the SVC to the power system are analyzed. The IPLAN, which is a high level language used with PSS/E program, is employed for determining the total transfer capability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.904-910
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• 2001

Static and oscillatory loss of stability of composite pipes conveying fluid is investigated. The theory of thin walled beams is applied and transverse shear, rotary inertia, primary and secondary warping effects are incorporated. The governing equations and the associated boundary conditions are derived through Hamilton's variational principle. The governing equations and the associated boundary conditions are transferred to eigenvalues problem which provides the information about the dynamic characteristics of the system. Numerical analysis is performed by using extended Gelerkin method. Critical velocity of fluid is investigated by increasing fiber angle and mass ratio of fluid to pipe including fluid.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.42-42
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• 2000

This paper concerns an efficient aperiodic static crab walking algorithm for quadruped walking machine in rough terrain. In this algorithm, the requirements for forward stability margin and backward stability margin could be given differently in order to consider the slope of terrain and disturbances resulting from moving velocity. To restrict the searing regions for motion variables, such as moving distances until a leg is lifted or is placed, the standard leg transferring sequence is decided to be that of wave gaits. standard support pattern is also proposed that enables the quadruped to continue forward motion using the standard leg transferring sequence without falling into deadlock.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.43-53
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• 2006

Aerodynamic shape design of the Mid-sized Aerostat was performed with computational fluid dynamics. Design procedure included determination of hull volume and length, hull shape, tailfin configuration with anhedral and location, tailfin section. For aerodynamic analysis, three dimensional Navier-Stokes equations were applied with Spalart-Allmaras turbulence model. During design procedure, static moment derivatives were mainly considered for the stability of aerostat and structural limitations were also considered for practical application of the designed shape. Aerodynamic analysis of the designed aerostat was carried out and aerodynamic characteristics were compared with those of the TCOM 71m aerostat, one of the most successful commercial aerostats. It was found that the designed KARI Mid-sized Aerostat had better stability characteristics compared to the TCOM 71m aerostat.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.495-505
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• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.743-745
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• 1996

This paper presents an approach for the analysis of static voltage stability in power system. The proposed approach is based on multiple load flow calculation method using the redistribution algorithm of transmission loss, with which more realistic load flow solution can be obtained in the near of voltage collapse point. Some simulation results of the proposed approach show that the accuracy of static voltage stability analysis can be increased.

• The Transactions of the Korean Institute of Power Electronics
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• v.1 no.1
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• pp.47-55
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• 1996

A new generator excitation system using a boost-buck chopper as a kind of static exciters is proposed to overcome the lack of field forcing capability of the bus fed exciter under the input line fault condition. It increases or maintains the generator field current by boosting the field voltage in the case of the input AC line voltage drop during and immediately after a fault. The validity of the proposed excitation system is verified with the computer simulation. The generator stability according to the each difference exciter is tested using a commercial software package-CYME. The simulation results of the stability analysis on the generator with the proposed exciter is better than that of the bus fed exciter. This boost-buck chopper exciter can be simply implemented and controlled by the modern power electronics technology.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.4
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• pp.208-213
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• 2018

In this paper, we studied the control strategy of applying STATCOM(static synchronous compensator) to mitigate the FIDVR(fault induced delayed voltage recovery) phenomenon. The proportion of motor loads is gradually increasing which might affect power system stability. Excessive reactive power consumption by the stall of the motor loads causes FIDVR phenomenon. In addition, the low inertia of the small HVAC(heating, ventilation and air conditioner) unit will not separate itself in the event of a contingency, causing system instability. For this reason, we have developed a control strategy that utilizes STATCOM efficiently through static and dynamic analysis. Case studies on a Korean power system have validated the performance of the proposed scheme under severe contingency scenarios. The results have verified that the proposed strategy can effectively mitigate FIDVR and improve the stability and reliability of the system.