• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.870-877
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• 2014

Geostationary satellites undergo various orbital perturbations and this results in location change. Therefore, all the geostationary satellites use the thruster in order to control the location change. For this purpose, the suitable amount of liquid propellant is mounted and the amount of propellant is reduced as time goes by. This means that the lifetime of the satellite depends on the residual propellant amount. Therefore precise residual propellant gauging is very important for the mitigation of economic losses arised from premature removal of satellite from its orbit, satellites replacement planning, slot management and so on. In this paper, we introduce the propellant gauging methods used in the geostationary satellites and the propellant gauging method studied in the laboratory level.

• Steel and Composite Structures
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• v.25 no.4
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• pp.485-496
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• 2017

In this paper, damage detection has been introduced as an optimization problem and a two-step method has been proposed that can detect the location and severity of damage in truss structures precisely and reduce the volume of computations considerably. In the first step, using the residual force vector concept, the suspected damaged members are detected which will result in a reduction in the number of variables and hence a decrease in the search space dimensions. In the second step, the precise location and severity of damage in the members are identified using the genetic algorithm and the results of the first step. Considering the reduced search space, the algorithm can find the optimal points (i.e. the solution for the damage detection problem) with less computation cost. In this step, the Efficient Correlation Based Index (ECBI), that considers the structure's first few frequencies in both damaged and healthy states, is used as the objective function and some examples have been provided to check the efficiency of the proposed method; results have shown that the method is innovatively capable of detecting damage in truss structures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4957-4976
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• 2016

This paper investigates the error performance of the amplify-and-forward (AF) relaying systems in the context of full-duplex (FD) communication. In addition to the inherent self-interference (SI) due to simultaneous transmission and reception, coexistent FD terminals may cause crosstalk. In this paper, we utilize the information exchange via the crosstalk channel to construct a particular distributed space-time code (DSTC). The residual SI is also considered. Closed-form pairwise error probability (PEP) is first derived. Then we obtain the upper bound of PEP in high transmit power region to provide more insights of diversity and coding gain. The proposed DSTC scheme can attain full cooperative diversity if the variance of SI is not a function of the transmit power. The coding gain can be improved by lengthening the frame and proper power control. Feasibility and efficiency of the proposed DSTC are verified in numerical simulations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.207-210
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• 1998

Electrical properties such as space charge distribution and electrical conduction of XLPE/VLDPE blends were studied. When the VLDPE is blended, residual charge inside XLPE increases. In case of electrical conduction characteristics, there were no changes in electrical conduction mechanism, space charge limited conduction. XLPE/VLDPE blend including crosslinking coagent showed relatively small current density. It might be due to the carbonyl group in crosslinking coagent.

• Bulletin of the Korean Mathematical Society
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• v.47 no.2
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• pp.287-293
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• 2010

It is well known that there is a residual subset J of the space of $C^1$-diffeomorphisms on a compact Riemannian manifold M such that the maps f $\mapsto$ chain recurrent set of f and f $\mapsto$ number of chain components of f are continuous on J. In this paper we get the flow version of the above results on diffeomorphisms.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1463-1467
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• 2005

This paper proposes an analytical redundancy technique for fault diagnostics of the sensor in steer-by-wire system. We use incorporating vehicle dynamics modeling into the design of a diagnostic system for steer-by-wire system. The use of a model of vehicle dynamics improves the speed and accuracy of the diagnoses. The proposed fault diagnostics algorithm is based on parity-space methods to generate residuals. To reduce the effects of modeling uncertainty and dynamic transients, the residuals are subject to filtering. We construct diagnostic system consisting residual threshold for detection and isolator with using the directional residual vector.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.48-55
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• 2006

A multi-filter fusion technique is proposed and this technique is applied to the INS/GPS integrated system. IIR-type EKF and FIR-type RHKF filter are fused to provide the advantages of these filters based on the adaptive mixing probability calculated by the residuals and the residual covariance matrices of the filters. In the INS/GPS, this fusion filter can provide more robust navigation information than the conventional stand-alone filter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.27-33
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• 2003

A method for the retardation of fatigue crack growth using ring indentation at the vicinity of a crack is examined. Residual stresses near crack tip are evaluated using fracture mechanics approach using the Bueckner weight function. The motivation is to develop a simple and effective method for obtaining an increase in fatigue lives to total failure of materials with crack. Fatigue testing of aluminum specimen showed that the retardation effects are observed after the application of the method.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.34.3-34.3
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• 2009

We have investigated the recent star formation history of the nearby galaxies using the SDSS optical and Galex UV data. To everyone's surprise, we found that roughly 30 percent of elliptical galaxies had a residual star formation in the last billion years, suggesting that residual star formation has been common even in ellipticals. Galaxy evolution models based on semi-analytic prescriptions including AGN feedback reasonably reproduce the star formation properties of elliptical galaxies. However, we found that the current galaxy models miserably fail to reproduce the star formation properties of satellite disc galaxies in cluster environments. Satellite disc galaxies in models are overly star-formation quenched in comparison to observation. Detailed investigations led us to conclude that this is due to the use of inaccurate prescriptions for the gas content evolution in the model. I present a solution to the problem by adopting more realistic physical prescriptions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1841-1852
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• 1992

With the wide application of fiber-reinforced composite material in aircraft, space structures and robot arms, the design and manufacture of composite joints have become a very important research area because they are often the weakest areas in composite structures. In this study, the effects of the adhesive thickness, residual thermal stress on the torque capacity of the tubular single lap joints were studied. The torque capacity of the adhesive joints were experimentally determined and found to be inversely proprotional to the adhesive thickness. In order to match the experimental results to the theoretical analyses, the elastic-perfectly plastic material properties of the adhesive were used in the closed form solution. Also, the residual thermal stress of the joints were calculated by the finite element method and it was proved that the residual thermal stress could play an important role in the thick adhesive joints.