• ETRI Journal
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• v.26 no.6
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• pp.520-534
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• 2004

As the density of memories increases, unwanted interference between cells and the coupling noise between bit-lines become significant, requiring parallel testing. Testing high-density memories for a high degree of fault coverage requires either a relatively large number of test vectors or a significant amount of additional test circuitry. This paper proposes a new tiling method and an efficient built-in self-test (BIST) algorithm for neighborhood pattern-sensitive faults (NPSFs) and new neighborhood bit-line sensitive faults (NBLSFs). Instead of the conventional five-cell and nine-cell physical neighborhood layouts to test memory cells, a four-cell layout is utilized. This four-cell layout needs smaller test vectors, provides easier hardware implementation, and is more appropriate for both NPSFs and NBLSFs detection. A CMOS column decoder and the parallel comparator proposed by P. Mazumder are modified to implement the test procedure. Consequently, these reduce the number of transistors used for a BIST circuit. Also, we present algorithm properties such as the capability to detect stuck-at faults, transition faults, conventional pattern-sensitive faults, and neighborhood bit-line sensitive faults.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.132-132
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• 2015

Virtual metrology (VM) model based on plasma information (PI) parameter for C4F8 plasma-assisted oxide etching processes is developed to predict and monitor the process results such as an etching rate with improved performance. To apply fault detection and classification (FDC) or advanced process control (APC) models on to the real mass production lines efficiently, high performance VM model is certainly required and principal component regression (PCR) is preferred technique for VM modeling despite this method requires many number of data set to obtain statistically guaranteed accuracy. In this study, as an effective method to include the 'good information' representing parameter into the VM model, PI parameters are introduced and applied for the etch rate prediction. By the adoption of PI parameters of b-, q-factors and surface passivation parameters as PCs into the PCR based VM model, information about the reactions in the plasma volume, surface, and sheath regions can be efficiently included into the VM model; thus, the performance of VM is secured even for insufficient data set provided cases. For mass production data of 350 wafers, developed PI based VM (PI-VM) model was satisfied required prediction accuracy of industry in C4F8 plasma-assisted oxide etching process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2279-2284
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• 2011

In most of radial distribution systems, the overcurrent protection coordination is adopted for the protection of apparatus and the improvement of electrical power system reliability. The protection coordination structure in distribution substation is composed of several circuit breakers(CB) with distribution lines originating from one substation bus under one transformer, which trip for their fault current. But sufficient analysis is necessary for the capacity of CB's in distribution systems with several distribution generations(DG). In this paper, a protection coordination method not to exceed the traditional capacity of CB's was proposed and certified through simulation by the PSCAD-EMTDC S/W.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.151-159
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• 2003

According to the records, approximately 50 percent of power failure were caused by lightning. Conventional fault preventive measures against lightning include reduction of the footing resistance of the tower, multiplication of overhead ground wires and unbalanced insulation of the double circuit transmission tower. In addition to these, transmission line arresters have been recently appeared as an alternatives. In this paper an unbalanced insulation method with transmission line arrester was assumed as another countermeasure against simultaneous double circuit trip of 154 kV transmission line by lightning strike. The lightning performance of line arrester was compared with conventional insulation concept using different numbers of porcelain and glass insulator. Larger numbers of insulator simply increase flashover current level by lightning but the lightning performance doesn't proportional to it. EMTP simulation and predictive calculation of lightning failure rate were carried out to evaluate the performance.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.383_384
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• 2009

After the 1970s, the importance of underground transmission systems increased and the construction rate of underground transmission lines also showed increasing trends each year, especially in metropolitan areas. Accordingly the social ripple effects are very large and wide when the fault occurs in underground power system, and the amount of time and money spent to restore the system also increases. So we must ensure stable operation and long-term reliability of the facilities. In Korea's case, long-term reliability tests for EHV power cables and accessories progressed poorly because equipment was not compatible for long-term reliability tests. Therefore we planned to construct a long-term reliability test field for EHV underground cables in order to ensure international quality reliability and optimal power cable operation techniques. The Gochang Underground Cable Test Field is under construction, funded by the Korean government, the govenment's union investment department, KEPCO, KERI and three private cable corporations. This project began in March, 2005 and will be completed by February, 2010. It is designed to promote joint research by incorporating several types of test equipment, construction of operating facilities, and being an internationally certified authority.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.470-473
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power. Therefore, there has been and still is a growing concern (safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline. especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion, limitation of safety voltage and analysis of indiction voltage.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.847-853
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• 2010

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with XLPE power cable. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as length ratio of power cable section, arrestor, inserting resistance, charging rate, grounding resistance, etc.. On the other hand sheath voltage on IJ(Insulated Joint) is analyzed to check dangerous condition on cable cover. Analysis is performed by EMTP/ATP. Analysis results show that reclosing can be operated as the single line-to-ground fault occurs on overhead line in 345kV combined transmission line, if the inserting resistance is considered before the operation of main circuit breaker.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.188-188
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• 1999

The embedded atom method (EAM) of Daw and Baskes as a semiempirical method, has been successfully applied to the fcc or nearly filled d-band transition metals due to its computational feasibility and its methodological simplicity. Then Baskes modified the EAM (MEAM) to include directional bonding and applied it to metals, semiconductors, and diatomic gases, all of which have different types of bondings. Here, we present a detailed study of the energetics of adsorption on the fcc(111) surfaces and binary system within the framework of MEAM. In adsorption on fcc(111) surfaces, there are two energetically favored sites, so called, fcc site and hcp site, which may trigger stacking fault in the growth of films and might switch growth mode between 3D growth and layer by layer growth. We scrutinized the role of the hcp sites, which would offer dynamic growth pathways although the dynamics are not yet clear within the limited experimental resolution. Featuring these transient motions in the atomic level should contribute to the understanding the growth mechanisms on fcc(111) surface. And we also applied MEAM for initial stage energetics at the Cr coverage of sub- monolayer on W(110). We hope that recently observed extraordinary growth behavior at the Cr coverage of 0.7 monolayer, self- organized nano-scale lines, can be resolved in this MEAM binary system calculation.

• Progress in Superconductivity and Cryogenics
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• v.6 no.2
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• pp.11-14
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• 2004

YBCO thin films have good characteristics for current limiting materials due to compact size and high current carrying capability. But the irregularities and the extreme thin thickness of YBCO films cause some difficulties in simultaneous quench and thermal shock protection. In order to solve these problems, vertical magnetic field generated from solenoid coil was applied to the YBCO element. And also to minimize the inductance caused by the serial connection of magnetic field source with superconducting elements, magnetic field source was separated from the power lines adapting protective current transformer. In this study, electric field-current (E-I) and quench characteristics of YBCO films were analyzed both by electrical measuring method and observations of bubble propagation. From the experiment results, it was revealed that the magnetic fields generated by surrounding coil could induce the uniform quench distribution for all stripes of current limiting units and finally simultaneous quenches were realized in all serial connection of YBCO elements. In addition, the separation of magnetic field source form electrical network could be good solution for simultaneous quench of YBCO films without any unnecessary effect caused by serial connection.

• Fire Science and Engineering
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• v.15 no.2
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• pp.20-30
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• 2001

The science and technology of seismic hazard mitigation are increasingly being shared among scientists and policy makers around the world. Administrative expertise is also being shared. While there is still tremendous unevenness in technical and administrative capacities and resources, a global community of emergency managers is developing and there is a globalization of expertise. Hazards are better understood, tools for risk assessment are improving, techniques for hazard mitigation are being perfected, and communities and states are implementing more comprehensive disaster preparedness, response, and recovery programs. Priorities are also emerging and hazard mitigation has emerged as the priority of choice in North America and Europe. An increasingly important component of hazard mitigation is resilience, in terms of increased capacities for disaster mitigation and recovery at the community and even individual levels. Each year, more is known about the locations and natures of seismic hazards, although there are still unknown and poorly understood fault lines and limited understanding of related disasters such as tsunamis and landslides. More is known about the impact of earthquakes on the built environment, although nature still provides surprises to confound man's best extorts to reduce risk. More is known about human nature and how people respond to uncertain risk and when confronted by certain catastrophe. However, despite the increased understanding of seismic phenomena and how to protect people and property, there is much that needs to be done to reduce the risk, particularly in major metropolitan areas.