• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.2
• /
• pp.98-106
• /
• 2013

This paper proposes fault tolerant control laws using sliding mode control and adaptation laws for a satellite with reaction wheel faults. Considering system parameter errors and faults uncertainties in the dynamics of satellite, the control laws were designed. It was assumed that only reaction wheel failures occurred as faults. The reaction wheel faults were reflected in the multiply form. Because the proposed control laws satisfy the Lyapunov stability theorem, the stability is guaranteed. Through computer simulation, it was assured that the proposed adaptive sliding mode controller has a better performance than the existing sliding mode controller under unstable angular rates.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.11
• /
• pp.2846-2859
• /
• 1994

This work deals with kinematic analysis of fault-tolerant 3 degree-of-freedom spherical modules which have force redundancies in its parallel structure. The performance of a redundantly actuated four-legged module with no actuator failure, a single actuator failure, partial and half failure of dual actuator are compared to that of a three-legged module, in terms of maximum force transmission ratio, isotropic characteristics, and fault-tolerant capability. Additionally, a system with an excess number of small floating actuators is considered, and the contribution of these small actuators to the force transmission and fault-tolerant capability is evaluated. This study illustrates that the redundant actuation mode allows significant saving of input actuation effort, and also delivers a fault tolerance.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.4
• /
• pp.315-321
• /
• 2012

The utility-interactive inverter with critical loads should supply continuous and stable voltage to critical loads even during the grid fault. The conventional control method which performs current control for grid-connected mode and voltage control for stand-alone mode undergoes the critical load voltage variation during grid fault. The critical load voltage may have large transient when the inverter performs mode transfer after the islanding detection. Recently, the indirect current control method which does not have the transient state during not only islanding detection but also the mode transfer has been proposed. However, since the voltage control is maintained even during the grid-connected mode it is difficult to detect the islanding. This paper proposes an active anti-islanding method suitable for the indirect current control method which does not have NDZ(Non-Detection Zone).

• The Journal of Engineering Geology
• /
• v.19 no.3
• /
• pp.277-285
• /
• 2009

In order to assess the fault behavior by the geometric analysis of fault slip, the study area between Yangsan city and Shinkwang-myon, Pohang city along the strike of the Yangsan fault is divided into 5 domains($A{\sim}E$ domains) based on the strike change of main fault, the type of fault termination, the cyclic variation of fault zone width, deformation pattern of fault rocks and angular deviation of secondary shears. And, we would apply the relationship between the mode of fault sliding and the resultant deformation texture obtained from previous several experimental studies of simulated fault gouge to the study of the Yangsan fault. To understand sliding behavior of the fault we measured the data of fault attitude and fault slip, and analyzed relationships between the main fault and secondary Riedel shear along the Yangsan fault. The sliding behavioral patterns in each section were analyzed as followings; the straight sections of A, D and E domains were analyzed as the creeping section of stably sliding. In contrast, the curved section of B domain was analyzed as the locked section of stick-slip movement.

• Journal of Power Electronics
• /
• v.19 no.4
• /
• pp.968-979
• /
• 2019

Recently, there has been increased interest in the study of multiphase machines due to their higher fault-tolerant capability when compared to their conventional three-phase counterparts. For six-phase machines, stator windings configured with a single isolated neutral (1N) provide significantly more post-fault torque/power than two isolated neutrals (2N). Hence, this configuration is preferred in applications where post-fault performance is critical. It is well known that min-max injection has been commonly used for three-phase and multiphase machines in healthy condition to maximize the modulation limit. However, there is a lack of discussion on min-max injection for post-fault condition. Furthermore, the effects in terms of the common-mode voltage (CMV) in modulating signals has not been discussed. This paper investigates the effect of min-max injection in post fault-tolerant control on the voltage and speed limit of a symmetrical six-phase induction machine with single isolated neutral. It is shown that the min-max injection can minimize the amplitude of reference voltage, which maximizes the modulation index and post-fault speed of the machine. This in turn results in a higher post-fault power.

• The Journal of the Korea Contents Association
• /
• v.2 no.1
• /
• pp.86-97
• /
• 2002

In this thesis, we propose a high-speed information network management mode based on layering and partitioning concepts of ITU-T G.805 We describe an information mood of the configuration of VP and VC networks and an information mode to manage faults in high-speed information networks. In order to efficient manage faults, us distinguish between an alarm with a fault that has negative effects on services and an alarm with an alert that barely affects services. Thus, we propose two types of computational models to treat all of these alarms, a fault alarm processing system and an alert alarm processing system. We also describe procedures of alarm processing and we describe the scope and processing course of NMS and SubNMS when rerouting a fault VP and VC fault connection. Lastly, we describe the implementation and analysis of the performance of the proposed fault alarm processing system. We compare the alarm processing tire of each priority according to the alarm occurrence ratio.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.05a
• /
• pp.46-48
• /
• 2006

We investigated the analysis of operation mode of three-phase flux-lake type superconducting fault current limiter(SFCL). The structure of the integrated three-phase flux-lock type SFCL consisted of three-phase flux-lock reactor wound on an iron core with the same turn between coil 1 and coil 2 in each phase. When the SFCL is operated under the normal condition, the flux generated in the iron core is zero because the flux generated between two coils of each single phase is canceled out. Therefore, the SFCL's impedance is zero and the SFCL has negligible influence on the power system, However, if a fault occurs in any single-phase among three phases, the flux generated in the iron core is not zero any more. The flux makes elements of all phase-quench irrespective of the fault type, which reduces the current of fault phase as well as the current of sound phase.

• Journal of Information Processing Systems
• /
• v.2 no.3 s.4
• /
• pp.163-169
• /
• 2006

So far, little research has been conducted into developing a QAPM (Quality Assurance Process Model) for telecommunications applications on the basis of TMN. This is the first trial of the design of TMN-based QAPM on fault management with UML. A key attribute of the QAPM is that it can easily identify current deficiencies in a legacy system on the basis of TMN architecture. Using an empirical comparison with the legacy systems of a common carrier validates the QAPM as the framework for a future mode of the operation process. The results indicate that this paper can be used to build ERP(Enterprise Resource Planning) for a telecommunications fault management solution that is one of the network management application building blocks. The future work of this paper will involve applying the QAPM to build ERP for RTE (Real Time Enterprise) fault management solution and more research on ERP design will be necessary to accomplish software reuse.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.339-342
• /
• 2001

In this paper, the characteristics of the shielded inductive superconducting fault current limiter(FCL) were simulated and analyzed to search for the parameter to determine FCL operation, Fault current limiting operation can be executed as resistive or inductive type, which is determined by iron-core radius and the number of the primary coil turns. It was considered through this paper that the operation of each was compared and examined about the merit of each mode.

• Journal of Power System Engineering
• /
• v.13 no.1
• /
• pp.59-64
• /
• 2009

Electronic control system of the engine is composed of various sensors and actuators, This paper is concerned with fault analysis for the stable operation of it. We suggest the technology that can systematically and reliably analyze fault causes of sensors and actuators by using the fault generating program. In results, we can acquire the systematic road map of occurring faults as well as the valuable information related to the operations of sensors and actuators. These results should be very useful to get the classification of fault causes, develop an electronic control system of engine, and review control strategies of it.