• Journal of the Korea Society of Computer and Information
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• v.27 no.5
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• pp.11-19
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• 2022

In this paper, we propose a fault tolerant embedded system using memory redundancy on the full-virtualization based virtual machine monitor. The proposed virtual machine monitor first virtualizes main memory of embedded system utilizing efficient shadow page table scheme so that the embedded system runs as a virtual machine on the virtual machine monitor. The virtual machine monitor makes the backup of the embedded system run as another virtual machine by copying memory contents of the embedded system into memory space of backup system according to predefined schedules. When an error occurs in the target virtual machine, the corresponding standby virtual machine takes the role of target virtual machine and continues its operation. Performance evaluation studies show that such backups and switches of virtual machines are performed with minor performance degradation.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.667-673
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• 2010

The near fault ground motion (NFGM) is characterized by a single long period velocity pulse with large magnitude. NFGMs have been observed in recent strong earthquakes, Northridge (1994), Japan Kobe (1995), Turkey Izmit (1999), China Sichuan (2008), Haiti (2010) etc. These strong earthquakes have caused considerable damage to infrastructures because the epicenter was close to the urban area, called as NFGM. Extensive research for the far field ground motion (FFGM) have been carried out in strong seismic region, but limited research have been done for NFGM in low or moderate seismic regions because of very few records. The purpose of this research is to investigate and analyze the seismic response of reinforced concrete bridge piers subjected to near-fault ground motions. The seismic performance of six RC bridge piers depending on three confinement steel ratios and three superstructure mass was investigated on the shaking table. From these experimental results, it was confirmed that the reduction of seismic performance was observed for test specimens with lower confinement steel ratio or more deck weight. The displacement ductility of RC bridge piers in terms of the stiffness degradation is proposed based on test results the shaking table.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.265-272
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• 2003

As VLSI systems become integrated at large-scale, logic fault or delay fault may result from crosstalk noise originated from cross coupling capacitance which exists between two adjacent wires. Because designers in industry do not have means to prevent crosstalk problems, they should check and adjust unsatisfactory designs after all designs are completed, if necessary. In this paper, we analyze how spacing, slew rate, line width, and line length influence the crosstalk, and suggest some solutions for the various factors that nay cause crosstalk problems. we also propose how to optimize the designs by using standardization of noise tables.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.959-962
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• 2002

This paper presents a method of constructing the universal multiple processing element unit(UMPEU) based on De Bruijn Graph. The proposed method is as following. Firstly we propose transformation operators in order to construct the De Bruijn graph using properties of graph. Secondly we construct the transformation table of De Bruijn graph using above transformation operators. Finally we construct the De Bruijn graph using transformation table. The proposed UMPEU is capable of constructing the De Bruijn geraph for any prime number and integer value of finite fields. Also the UMPEU is applied to fault-tolerant computing system, pipeline class, parallel processing network, switching function and its circuits.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.415-422
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• 2013

In this paper, we present Self-Checking look-up-table (LUT) based on Scalable Error Detection Coding (SEDC) scheme for use in fault-tolerant reconfigurable architectures. SEDC scheme has shorter latency than any other existing coding schemes for all unidirectional error detection and the LUT execution time remains unaffected with self-checking capabilities. SEDC scheme partitions the contents of LUT into combinations of 1-, 2-, 3- and 4-bit segments and generates corresponding check codes in parallel. We show that the proposed LUT with SEDC performs better than LUT with traditional Berger as well as Partitioned Berger Coding schemes. For 32-bit data, LUT with SEDC takes 39% less area and 6.6 times faster for self-checking than LUT with traditional Berger Coding scheme.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.146-149
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• 1995

A new method for grouping of relevant and equivalent inputs of a logical circuit was proposed by the authors by making use of pseudorandom M-sequence correlation. The authors show in this paper that it is possible to estimate the input grouping from a part of correlation functions when we admit small percentage of error, whereas it is impossible to reduce the data necessary to estimate the grouping by use of the truth table method. For example in case of 30-input logic circuit, the number of correlation functions necessary to calculate can be reducible from 1.07 * 10$^{9}$ to 465.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.199-206
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• 2006

Internet telephony provides voice communication services with added flexibility for multimedia extension at a lower cost compared to traditional telephone systems. We implemented an internet telephony system as an overlay network without a centralized server, using a distributed hash table (DHT). Compared to the current server-based internet telephony system, our system is fault-tolerant, scalable, and can be flexible extended to various services and advanced to integrated service. To demonstrate the high flexibility of our DHT-based internet telephony system, we made our system cooperate with web servers. Web users can check up others' online stales and establish voice communication sessions to online users at a mouse click. This technology can be applied to more complex services such as multimedia messaging or video conference service.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1302-1307
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• 2013

MOV(Metal Oxide Varistor) is the most important part of SPD(Surge Protective Device) which can protect electric facilities from an impulse current such as a lightning. So far, the fault of MOVs have decided only by surge count without considering magnitude of surge current and an amount of input energy. This paper proposed the fault prediction algorithm for the MOV using look up table made by surge count and input current data which have non-linear characteristics for input current and are estimated by high voltage experimental results. Proposed algorithm was proved by experiment on verification at a high voltage laboratory.

• Structural Engineering and Mechanics
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• v.37 no.3
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• pp.267-283
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• 2011

Although earthquakes generate random cyclic lateral loading on structures, a quasi-static cyclic loading pattern with gradually increasing amplitude has been commonly used in the laboratory tests because of its relatively low cost and simplicity compared with pseudo-dynamic and shake table tests. The number, amplitudes and sequence of cycles must be chosen appropriately as important parameters of a quasi-static cyclic loading pattern in order to account for cumulative damage matter. This paper aims to reach a new cyclic displacement pattern to be used in quasi-static tests of well-confined, flexure-dominated reinforced concrete (RC) columns. The main parameters of the study are sectional dimensions, percentage of longitudinal reinforcement, axial force intensity and earthquake types, namely, far-fault and near-fault.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.1-8
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• 2017

In this paper, we propose a fault tolerance technique which enables embedded systems to run without interruption while its operating system and tasks fail. In order to improve reliability, the proposed scheme makes an embedded system run as a virtual machine on virtual machine monitor. It also prepares a contingency virtual machine at which periodical backups of the embedded system are saved. When an error occurs in the main virtual machine, the corresponding standby virtual machine takes a role of the main virtual machine and continues its operation. Especially such backups and switches of virtual machines are performed with minor performance degradation by manipulating page table entries in virtual machine monitor. By conducting performance evaluation studies, we show that the proposed scheme makes embedded system robust against errors while it does not degrade the performance of the system significantly.