• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.266-269
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• 2004

A satellite ground control system (SGCS) which monitors and controls a geostationary satellite 24 hours a day has to achieve the system architecture assuring high-level availability and redundancy scheme. The SGCS for Communication, Ocean, and Meteorological Satellite (COMS) is currently being developed in Korea, which will be implemented to satisfy high availability (HA), expansibility, and compatibility in design. In order to implement the system architecture to meet these characteristics, the SGCS for COMS introduces the concept of the real-time distributed system structure based on redundancy scheme for high availability, data replication and sharing, and CORBA middleware.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.118-127
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• 2014

The configuration such as series, parallel and k-out-of-n of a repairable system directly affects its reliability. The maintenance strategy can also affect the overall performance of the system. The objective of this work is to investigate the possible trade-off between the configuration of a repairable k-out-of-n system and its maintenance strategy. The redundancy is considered to be the design decision variables, whereas the preventive maintenance period is considered to be the maintenance decision variables. The optimization model is used to minimize the overall life cycle cost associated with the system, considering constraint on reliability. Finally, genetic algorithm is used to find the optimal values for the decision variables. The result is compared with optimal values for considering redundancy and maintenance respectively.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.2
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• pp.37-50
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• 2003

A next generation small satellite HAUSAT-1, the first picosatellite developed in Korea, is being developed as one of the international CubeSat program by Space System Research Lab. of Hankuk Aviation University. A fault-tolerant incremental design methodology has been addressed in this paper. In this study, the effect of system redundancy on reliability was in details analyzed in accordance with the implementation of fault-tolerant system. Four different system recovery levels are proposed for HAUSAT-1 fault-tolerant system optimization. As a result, the HAUSAT-1 fault-tolerant system architecture design and reliability analysis has acquired about 11% reliability improvement.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1461-1466
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• 2004

Recently Domestic EMU's on board signal systems are gradually changed form Cab signal(Fix Block) to Distance-to-go. Interfaces with on board signal system, TCMS Redundancy structure is mainly required. This paper suggest Manaul/Automatic Driving based on TCMS-ATC interface and design of backup system which is operated by Stan-by Computer when one of it's Local Interface Unit(LIU) is out of oder. For the purpose of Precision Train Stop, Distance-to-go signal system require accuracy speed. Free-axle structure is required for this system This paper suggest Free-axle braking system that lack of brake-force is compensated by the distributed brake-force using TCMS. And one of braking system has out of order, compensation of brake-force for Free-axle system. Then we prove our design to Complete Car Test

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.1
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• pp.1-9
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• 2000

In this paper, a design method of fault-tolerance is presented for the nuclear digital control systems composed of software and hardware. As a quantitative design method measure of fault-tolerance, we used Reliability, Availability and Safety. To implement the proposed fault-tolerance, a prototype system has been devised for the digital control systems and a quantitative method of 'Markovian Model' is applied. The results provide the appropriate degree of redundancy and diversity, and fail-safe.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.527-532
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• 2007

In this paper, we suggest those two design plans for power supply method of Hot Standby Sparing System; one is the plan using MTBF based on Constant Failure Rate, and the plan using Reliability Function is the other. Traditionally, RBD (Reliability Block Diagram) is used for reliability prediction which is required to meet any requirements before system operation. However, the system that has redundancy, such as Hot Standby Sparing System, Is not suitable for system reliability modeling using combination model, such as RBD. In this paper, therefore, we demonstrate that for redundancy controller, redundancy modeling design toward fault occurrence design is more effective to build up a system with higher reliability and achieve the effectiveness of loss cost due to maintenance and failure occurred in operation, rather than combinational modeling design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1877-1886
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• 2010

In this paper, we design a redundancy control circuit for 1T-SRAM repair using electrical fuse programming. We propose a dual port eFuse cell to provide high program power to the eFuse and to reduce the read current of the cell by using an external program supply voltage when the supply power is low. The proposed dual port eFuse cell is designed to store its programmed datum into a D-latch automatically in the power-on read mode. The layout area of an address comparison circuit which compares a memory repair address with a memory access address is reduced approximately 19% by using dynamic pseudo NMOS logic instead of CMOS logic. Also, the layout size of the designed redundancy control circuit for 1T-SRAM repair using electrical fuse programming with Dongbu HiTek's $0.11{\mu}m$ mixed signal process is $249.02 {\times}225.04{\mu}m^{2}$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.33-40
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• 2005

The reliability of flight control system(FCS) for Unmanned Air Vehicle(UAV) is underestimated because of the design restrictions such as small size, low cost and light weight. However because the failure of FCS may cause the loss of aircraft, the reliability of FCS must be analysed and validated whether it meet the reliability requirements in design phase.In this paper the failure rate of subsystems was divided with its function based on the design experience of FCS. The redundancy models which satisfy the system reliability requirements were suggested. These results may be utilized in the hardware design of FCS.

• International Journal of Reliability and Applications
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• v.12 no.2
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• pp.79-94
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• 2011

Redundancy-reliability allocation problems in multi-stage series-parallel systems are addressed in this study. Fuzzy programming techniques are proposed for finding satisfactory solutions. First, a multi-objective programming model is formulated for simultaneously maximizing system reliability and minimizing system total cost. Due to the nature of uncertainty in the problem, the fuzzy set theory and technique are used to convert the deterministic multi-objective programming model into a fuzzy nonlinear programming problem. A heuristic method is developed to get satisfactory solutions for the fuzzy nonlinear programming problem. A Pareto optimal solution is found with maximal degree of satisfaction from the interception area of fuzzy sets. A case study that is related to the electronic control unit installed on aircraft engine over-speed protection system is used to implement the developed approach. Results suggest that the developed fuzzy multi-objective programming model can effectively resolve the fuzzy and uncertain problem when design goals and constraints are not clearly confirmed at the initial conceptual design phase.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.60-71
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• 1996

Mostof existing CAD systems do not provide the advanced function for systematic checking of design and drafting errors in mechanical drawings. We have reported a computer aided drawing check system to single plane projection drawings made by a CAD system. This paper describes a checking method of dimensioning errors in mechanical drawings. The checking items are deficiency and redundancy of dimensions, input-errors in dimension figures and symbols, etc. Checking for deficiency and redundancy of global dimensions has been performed applying Graph Theory. This system has been applied to several examples and we have confirmed the feasibility of this checking method.