• Journal of applied mathematics & informatics
• /
• v.8 no.2
• /
• pp.327-343
• /
• 2001

This is a survey article on finite element a posteriori error estimates with an emphasize on gradient recovery type error estimators. As an example, the error estimator based on the ZZ patch recovery technique will be discussed in some detail.

• 제어로봇시스템학회:학술대회논문집
• /
• 1988.10a
• /
• pp.518-523
• /
• 1988

A Teaching and Operating Expert System (TOES) was designed in order to perform a task effectively which is inaccessible to man. Once an error occurs in the middle of the task operation, the automatic mode is converted into a manual mode. After recovering the error by the manual mode, the manual mode should be converted into the automatic mode. It was necessary to improve the manual mode in order to increase the availability of a man-robot system, a part of the human interface technique. Therefore, the Error Recovery Expert System must be constructed and developed.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.12 no.4
• /
• pp.239-246
• /
• 2017

Time synchronization between distributed embedded systems in the Real Time Locating System (RTLS) based on Time Difference of Arrival (TDOA) is one of the most important factors to consider in system design. Clock jitter error between each system causes many difficulties in maintaining such a time synchronization. In this paper, we implemented a system to synchronize clocks between FPGA based distributed embedded systems using the recovery clock of CDR (clock data recovery) used in high speed serial communication to solve the clock jitter error problem. It is experimentally confirmed that the cumulative time error that occurs when the synchronization is not performed through the synchronization logic using the CDR recovery clock can be completely eliminated.

• Journal of Digital Contents Society
• /
• v.4 no.2
• /
• pp.139-146
• /
• 2003

This paper explains the design and implementation of the ERA(Error Recovery Agent). ERA is a system that is suitable for detecting, sharing and recovering software error based on multimedia distance education system. This system consists of an ED, ES, and ER. ED detects an error by hooking techniques. ES is an agent which is an error sharing system for distributed multimedia distance education system. We propose how an error application can be treated and recovered as 'media' in a multimedia collaborative environment.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.4
• /
• pp.135-141
• /
• 2000

The major role of temperature sensors in thermal error compensation system of machine tools is improving machining accuracy by supplying reliable temperature data on the machine structure. This paper presents a new method for fault diagnosis of temperature sensors and recovery of faulted data to establish the reliability of thermal error compensation system. The detection of fault and its location is based on the correlation coefficients among temperature data from the sensors. The multiple linear regression model which is prepared using complete normal data is also used fur the recovery of faulted data. The effectiveness of this method was tested by comparing the computer simulation results and measured data in a CNC machining center.

• Journal of Digital Contents Society
• /
• v.9 no.4
• /
• pp.785-790
• /
• 2008

Our Digital Carousel enables user to share media objects through media synchronization mechanism. We implemented the Digital Carousel so that the users participated in collaborative work may refer shared media or error objects as the same view to others. In this paper, we discuss a method for increasing reliability through fault tolerance. We describe the design and implementation of the ER running on distributed multimedia environment. ER is a system which is able to recover automatically a software error based on distributed multimedia. This paper explains a performance analysis of an error recovery system running on distributed multimedia environment using the rule-based DEVS modeling and simulation techniques. In DEVS, a system has a time base, inputs, states, outputs, and functions.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.10
• /
• pp.2618-2629
• /
• 1999

In this paper, we describe the design and implementation of the FDRA(Fault Detection Recovery based on Agent) running on distributed multimedia environment. DOORAE is a good example for distributed multimedia and multimedia distance education system among students and teachers during lecture. It has primitive service agents. Service functions are implemented with objected oriented concept. FDRA is a multi-agent system. It has been environment, intelligent agents interact with each other, either collaboratively or non-collaboratively, to achieve their goals. The main idea is to detect an error by using polling method. This system detects an error by polling periodically the process with relation to session. And, it is to classify the type of error s automatically by using learning rules. The merit of this system is to use the same method to recovery it as it creates a session. FDRA is a system that is able to detect an error, to classify an error type, and to recover automatically a software error based on distributed multimedia environment.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.403-406
• /
• 2003

In this paper, we have proposed a carrier recovery algorithm of OFDM/QPSK-DMR(Orthogonal Frequency Division Multiplexing/Quadrature Phase Shift Keying Modulation-Digital Microwave Radio)system using BL-PSF(Band Limited-Pulse Shaping Filter) and have analyzed the carrier phase MSE(Mean Square Error) performance of OFDM/QPSK and single carrier DMR systems. The existing OFDM/QPSK-DMR system using windowing requires training sequence or CP(Cyclic prefix) to synchronize a receive. carrier frequency. Because in the OFDM/QPSK-DMR system using BL-PSF there is no training sequence or CP(Cyclic Prefix), we also propose a carrier recovery useful to the system. The simulation results confirm that the proposed carrier recovery algorithm has the same carrier phase MSE(Mean Square Error) performance for the single carrier DMR system under AWGN(Additive White Gaussian Noise) environment.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.394-397
• /
• 2003

In this paper, we have proposed a clock recovery algorithm of OFDM/QPSK-DMR(Orthogonal Frequency Division Multiplexing/Quadrature Phase Shift Keying Modulation-Digital Microwave Radio)system using BL-PSF(Band Limited-Pulse Shaping Filter) and have analyzed the clock phase error variance performance of OFDM/QPSK and single carrier DMR systems. The existing OFDM/QPSK-DMR system using the windowing requires training sequence or CP(Cyclic Prefix) to synchronize a receiver clock frequency Because there is no training sequence or CP(Cyclic prefix) in our proposed DMR system, the proposed clock recovery algorithm is useful to the OFDM/QPSK-DMR system using BL-PSF, The simulation results confirm that the proposed clock recovery algorithm has the same clock phase error variance performance in a single carrier DMR system under AWGN(Additive White Gaussian Noise) environment.

• Journal of Advanced Navigation Technology
• /
• v.11 no.4
• /
• pp.479-484
• /
• 2007

This paper explains the design and implementation of the FRA(Fault Recovery Agent). FRA is a system that is suitable for recovering software error for multimedia distance education based on home network environment. In terms of distributed multimedia systems, the most important catagories for quality of service are a timeless, volume, and reliability. In this paper, we discuss a method for increasing reliability through fault tolerance. This paper explains a performance analysis of an error recovery system running on distributed multimedia environment using rule-based DEVS modeling and simulation techniques. In DEVS, a system has a time base, inputs, states, outputs, and functions. The proposed method is more efficient than the other method in comparison with error ration and processing time.