• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.269-275
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• 2001

In land navigation applications, two kinds of GPS/DR integration schemes are commonly used; the loosely-coupled integration scheme and the tightly-coupled one. The loosely-coupled integration filter has a simple structure and is easy to implement. When the number of visible satellites is insufficient, however, it cannot calibrate the errors of the DR sensors. On the contrary the tigthly-coupled integration filter can sup-press the growth of the error in the DR output even when the visibility is poor. However, it has larger com-putation load due to the state dimension and is inconsistent because of the variation in the measurement dimension. This paper presents a GPS/DR integration scheme with dual integration mode. During when the number of visible satellites is sufficient, the proposed scheme operates in a loosely-coupled integration mode. When the visibility becomes poor, it is switched into a tightly-coupled integration mode. Consequently, the pro-posed scheme can calibrate the DR sensors even when the visibility is poor. In addition, its computation time remains constant even if the number of visible satellites increases. Field experiment results show that the performance of the proposed integration method is almost similar to that of the tightly-coupled one.

• Korean Journal of Remote Sensing
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• v.18 no.2
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• pp.91-96
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• 2002

The performance characteristics of a satellite imager using a Time Delay and Integration(TDI) Charge Coupled Device (CCD) with fixed integration time is investigated for the variation of satellite altitude and tilt angle. In consequence of the investigation TDI synchronization using tilt imaging is proposed as a solution to compensate geometric performance degradation due to altitude decrease. The tilt angle optimized for the TDI synchronization at decreased altitude is presented. This result can be used for a TDI CCD imager with variable integration time in a certain range as well.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1127-1143
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• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.121-125
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• 2006

A new GPS receiver correlator for the deeply-coupled GPS/INS integration system is proposed in order to the computation time problem of the Kalman filter. The proposed correlator consists of two early, prompt and late arm pairs. One pair is for detecting data bit transition boundary and another is for the correlator value calculation between input and replica signal. By detecting the data bit transition boundary, the measurement calculation time can be made longer than data bit period. As a result of this, the computational time problem of the integrated Kalman filter can be resolved. The validity of the proposed method is given through computer simulations.

• Coupled systems mechanics
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• v.3 no.1
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• pp.1-25
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• 2014

In this work, we present the theoretical formulation, operator split solution procedure and partitioned software development for the coupled thermomechanical systems. We consider the general case with nonlinear evolution for each sub-system (either mechanical or thermal) with dedicated time integration scheme for each sub-system. We provide the condition that guarantees the stability of such an operator split solution procedure for fully nonlinear evolution of coupled thermomechanical system. We show that the proposed solution procedure can accommodate different evolution time-scale for different sub-systems, and allow for different time steps for the corresponding integration scheme. We also show that such an approach is perfectly suitable for parallel computations. Several numerical simulations are presented in order to illustrate very satisfying performance of the proposed solution procedure and confirm the theoretical speed-up of parallel computations, which follow from the adequate choice of the time step for each sub-problem. This work confirms that one can make the most appropriate selection of the time step with respect to the characteristic time-scale, carry out the separate computations for each sub-system, and then enforce the coupling to preserve the stability of the operator split computations. The software development strategy of direct linking the (existing) codes for each sub-system via Component Template Library (CTL) is shown to be perfectly suitable for the proposed approach.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.171-177
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• 2011

In this paper, a square simply supported panel flutter have been considered at high supersonic flow by using coupled fluid-structure (FSI) analysis that based on time domain method. The Reynolds-Average Navier Stokes (RANS) equation with Spalart-Allmaras turbulent model were applied for unsteady flow problems of panel flutter. A fully implicit time marching schemed based on the Newmark direct integration method is used for calculating the coupled aeroelastic governing equations of it. In addition, the SOL 145 solver of MSC.NASTRAN was used to investigate flutter velocity based on PK-method of Piston theory. Our numerical results indicated that there is a good agreement result between Piston Theory in MSC.NASTRAN and coupled fluid-structure analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.186-196
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• 1999

The CPS provides data with long-term stability independent of passed time and the INS provides high-rate data with short-term stability. By integrating these complementary systems, a highly accurate navigation system can be achieved. In this paper, a loosely-coupled GPS/INS integration system is designed. It is a simple structure and is easy to implement and preserves independent navigation capability of GPS and INS. The integration system consists of a NCU, an IMU, a GPS receiver, and a monitoring system. The navigation algorithm in the NCU is designed under the multi-tasking environment based on a real-time kernel system and the monitoring system is designed using the Visual C++. The integrated Kalman filter is designed as a feedback formed 15-state filter, in which the states are position errors, velocity errors, attitude errors and sensor bias errors. The van test result shows that the integrated system provides more accurate navigation solution then the inertial or the GPS-alone navigation system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.974-977
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• 2003

The GPS/INS integration system navigation can provide improved navigation performance and has been widely used as a main navigation system for military and commercial vehicles. When two navigation systems are tightly coupled and the structure is complicated, a fault in either the GPS or the INS can lead to a disastrous failure of the whole integration system. This paper proposes a real-time fault detection method for an AGPS/INS integration system. The proposed fault detection method comprises a BIT and a fault detection algorithm based on chi-square test. It is implemented by real-time software modules to apply the AGPS/INS integration system and van test is carried out to evaluate its performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.848-854
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• 2006

In this study, a computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-\omega$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used flow computing the coupled governing equations of the fluid-structure interaction problem. Detailed FIV responses for different flow conditions are presented with respect to time and vibration characteristics are also physically investigated in the time domain.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.251-256
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• 1994

Integration of intelligent robot workcell is now a hot issue in CIM and robotics area. This piper dealt with relatively low-level essential topics, i.e., multi-robot coordination and real-time communication for the integration of intelligent robot workcell. For the coordination of multi-robot system, the tightly-coupled coordination is proposed using the various sensors. In order to handle the numerous communication data, time-critical communication network (Field-bus) is introduced and investigated. Finally, intelligent robot workcell is suggested using the Mini-MAP and Field-bus.