• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.600-602
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• 2000

This paper deals with finite element analysis of 2GVA superconducting generator which has slitted electrothermal shield in d-axis. Open emf voltage is calculated and three phase fault is considered to Predict the generator parameters by F.E.M. Results show that quick response excitation could be applied to superconducting generator with slitted electrothermal shield.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.969-974
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• 2013

Protection issues in distribution systems which are to be operated in open and closed-loop modes in a smart grid are studied and a generalized protection setting method is proposed to meet the new requirements. The developed setting method assumes a conventional over-current protection scheme for the system with reclosers and over-current relays. In a closed-loop mode, it identifies protective devices that have to be sacrificed in order to maximize protection coordination for bidirectional fault current flow. The proposed setting method has been tested on many systems with different complexity and is proved effective.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.964-966
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• 1998

The TC curve of recloser which used in KEPCO's distribution line is a little different in a pattern with the TC curve of sub-station OCR. So it sometimes fails in protection coordination. And the recloser sometimes does mis-open/close owing to the inrush current of CB reclosing when a fault occurred on the source-side of the recloser. The mis-open/close is another trouble maker. This Paper Present a new delay TC curve of recloser which has the same pattern with the TC curve of OCR, and a new instantaneous TC curve of recloser which doesn't mal-function to the inrush current. In addition, this paper present another two TC curves for the serial positioning of 2 reclosers. So we accomplished the simple protection coordination of OCR-recloser-fuse.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.5
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• pp.538-544
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• 1999

One of the most important requirements for the development of computerized relay setting system is its openness to abbommodate the various changes like new panel additions. This paper describes the relay settein-coordination system(PROSET2000), which has an open system architecture and adopts the dbject oriented programming paradigm. Its main features include the intelligent fault type identification, automatic running of the short circuit analysis, ren-time rulebase modification, automatic documentation, ect.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.15-16
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• 2015

According to 2014 fire statistical yearbook in the National Fire Data System, a main cause of fire is electrical fire except carelessness fire. Joint/contact badness is the one of the main cause of electrical fire. Furthermore, power relays which are used in electric panel board, motor control center and automation controller, are main element of automation system in the industry field. Overload, voltage unbalance and open-phase due to joint/contact badness of terminal make electric accidents or electrical fires. In order to prevent joint/contact badness of terminal, this paper proposes a sensing circuit of chattering, tracking, arc current, voltage unbalance and open-phase etc. Some experimental tests of the proposed apparatus confirm practicality and validity of the theoretical results.

• Journal of Information Processing Systems
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• v.18 no.6
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• pp.741-754
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• 2022

Openstack is widely used as a representative open-source infrastructure of the service (IaaS) platform. The Openstack Identity Service is a centralized approach component based on the token including the Memcached for cache, which is the in-memory key-value store. Token validation requests are concentrated on the centralized server as the number of differently encrypted tokens increases. This paper proposes the practical Byzantine fault tolerance (PBFT) blockchain-based Openstack Identity Service, which can improve the performance efficiency and reduce security vulnerabilities through a PBFT blockchain framework-based decentralized approach. The experiment conducted by using the Apache JMeter demonstrated that latency was improved by more than 33.99% and 72.57% in the PBFT blockchain-based Openstack Identity Service, compared to the Openstack Identity Service, for 500 and 1,000 differently encrypted tokens, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.575-580
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• 2018

This paper discusses system for real-time monitoring of patient waiting time in hospitals based on open-source platform. It is necessary to make use of open-source projects to develop a high-performance stream processing system, which analyzes and processes stream data in real time, with less cost. The Hadoop ecosystem is a well-known big data processing platform consisting of numerous open-source subprojects. This paper first defines several requirements for the monitoring system, and selects a few projects from the Hadoop ecosystem that are suited to meet the requirements. Then, the paper proposes system architecture and a detailed module design using Apache Spark, Apache Kafka, and so on. The proposed system can reduce development costs by using open-source projects and by acquiring data from legacy hospital information system. High-performance and fault-tolerance of the system can also be achieved through distributed processing.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.449-456
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• 2005

Optical burst switching (OBS) overcomes the inefficient resource usage of optical circuit switching and minimizes the optical buffering requirement of optical packet switching. General switch management protocol (GSMP) is an open interface between a label switch and a controller, and it provides connection, configuration, performance, event management and synchronization. GSMP open interface in the OBS network allows the implementation of OBS switch to be simple by separating the data forward plane from the control plane. We defined managed objects to support connection, configuration, performance, and fault management for the management of OBS network in the GSMP open interface. We proposed the network management model, in which the above managed objects are distributed in a controller and an OBS switch according to network management functions. We verified the possibility of connection management using distributed network management model in the GSMP open interface of OBS network by implementing GSMP and network management functions with managed objects of OBS.

• Transactions on Electrical and Electronic Materials
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• v.10 no.2
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• pp.53-57
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• 2009

In this paper we develop a method to observe faults in semiconductor devices and transmission lines by calculating the variation of the reflection function in a dielectric microstrip line that has an open-ended termination containing an optically induced plasma region. It is analyzed with the assumption that the plasma is distributed homogeneously in laser illumination. With the non linear material of degradation, the concentration of the carrier in the part of the material has changed. Since the input wave has produced the phenomenon of reflection, the input signal to the open-ended microstrip lines can be observed on reflection to identify the location of the fault. The characteristic impedances resulting from the presence of plasma are evaluated by the transmission line model. The variation of the reflection wave in the microwave system has been calculated by using an equivalent circuit model. The transient response has been also evaluated theoretically for changing the phase of the variation in the reflection. The variation of characteristic response in differentially localized has been also evaluated analytically.

• Journal of Power Electronics
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• v.19 no.1
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• pp.288-295
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• 2019

Rectifiers are widely used in industrial applications. Although detailed models of rectifiers are usually used to evaluate their performance, they are complex and time-consuming. Therefore, the Average Value Model (AVM) has been introduced to meet the demand for a simple and accurate model. This type of rectifier modeling can be used to simplify the simulations of large systems. The AVM of diode rectifiers has been an area of interest for many electrical engineers. However, healthy diode rectifiers are only considered for average value modeling. By contrast, faults occur frequently on diodes, which eventually cause the diodes to open-circuit. Therefore, it is essential to model bridge rectifiers under this faulty condition. Indeed, conventional AVMs are not appropriate or accurate for faulty rectifiers. In addition, they are significantly different in modeling. In this paper, a novel application of the parametric average value of a three-phase line-commutated rectifier is proposed in which one diode of the rectifier is considered open-circuited. In order to evaluate the proposed AVM, it is compared with experimental and simulation results for the application of a brushless synchronous generator field. The results clearly demonstrate the accuracy of the proposed model.