• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1025-1033
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• 2010

This paper proposes a method to improve and analysis error cause of FI(Fault Indicator) information to be used for detecting fault section in distribution automation system. FI error cause is made by consideration fault current magnitude and time. So, a new method to prevent FI error is proposed to include fault current magnitude, time and direction. Therefore, it's considered network environments that grounded and ungrounded network in distribution automation system. The proposed method is proved by Matlap Simulink. By the result in this research, it's possible to quickly restoration, supplying stability and reliability power to customer.

• IE interfaces
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• v.12 no.3
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• pp.401-405
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• 1999

We present a simulation model to generate the spatial distribution of mobiles in cellular communication network. Three types of spatial distributions are considered; biased, random, and ratio-based distributions. This study also points out and corrects the critical errors performed by Das and Morgera(1997) in getting random location of mobiles. By applying a simple path loss model, the effects of our correction on the signal-to-interference(SIR) ratio are discussed. The numerical results indicate that the variation of SIR in the Das's biased distribution is larger than that of other distributions. As compared with the random distribution, the average SIR error of the biased distribution is 91.1%.

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.42-47
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• 2004

This paper presents the various application programs for the Distribution Automation System (DAS) of the Korea Electric Power Corporation (KEPCO)'s distribution system. These programs are developed to allow for optimal operation in the areas of feeder automation, relay coordination, loss minimization and so on. They are single line diagram auto creation programs for the feeder, service restoration program, protection coordination program, data error detection program, and optimal network reconfiguration program. The details of these programs are presented for validity and effectiveness.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.404-406
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• 2006

본 논문에서는 우주전파를 VLBI 관측시스템으로 관측한 후 고속으로 저장/재생하기 위한 시스템 구축에 관해 소개한다. 한국천문연구원에서는 2001년부터 국내 유일의 VLBI관측 시스템으로써 한국우주전파관측망(Korean VLBI Network; KVN)을 구죽하고 있다. KVN에서는 1Gsps/2bit 우주전파를 샘플링하는 샘플러와 디지털필터로 구성된 자료획득 시스템(Data Acquisition System; DAS)을 갖출 예정이다. 관측된 우주전파는 샘플러와 DAS를 통하여 처리된 데이터를 1Gbps이상의 속도로 기록된다. 본 논문에서는 1Gbps급의 대용량 데이터를 처리할 수 있는 시스템으로써 Mark5B 시스템의 구축과 시스템 구성, VSI-H, 시스템 운용 및 실험결과 등에 대해서 기술하고자 한다.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1315-1320
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• 2016

The present study aims to predict the heat transfer characteristics around a square cylinder with different corner radii using multivariate adaptive regression splines (MARS). Further, the MARS-generated objective function is optimized by particle swarm optimization. The data for the prediction are taken from the recently published article by the present authors [P. Dey, A. Sarkar, A.K. Das, Development of GEP and ANN model to predict the unsteady forced convection over a cylinder, Neural Comput. Appl. (2015) 1-13]. Further, the MARS model is compared with artificial neural network and gene expression programming. It has been found that the MARS model is very efficient in predicting the heat transfer characteristics. It has also been found that MARS is more efficient than artificial neural network and gene expression programming in predicting the forced convection data, and also particle swarm optimization can efficiently optimize the heat transfer rate.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.382-394
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• 2010

Cross-domain event information sharing is a topic of great interest in the area of event based network management. In this work we use data sets which represent actual attacks in the operational Internet. We analyze the data sets to understand the dynamics of the attacks and then go onto show the effectiveness of sharing incident related information to contain these attacks. We describe universal data acquisition system for event based management (UniDAS), a novel system for secure and automated cross-domain event information sharing. The system uses a generic, structured data format based on a standardized incident object description and exchange format (IODEF). IODEF is an XML-based extensible data format for security incident information exchange. We propose a simple and effective security model for IODEF and apply it to the secure and automated generic event information sharing system UniDAS. We present the system we have developed and evaluate its effectiveness.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.63-70
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• 2015

The numerous improved schemes of user authentication based on password have been proposed in order to prevent the data access from the unauthorized person. The importance of user authentication has been remarkably growing in the expanding application areas of wireless sensor networks. Recently, emerging wireless sensor networks possesses a hierarchy among the nodes which are divided into cluster heads and sensor nodes. Such hierarchical wireless sensor networks have more operational advantages by reducing the energy consumption and traffic load. In 2012, Das et al. proposed a user authentication scheme to be applicable for the hierarchical wireless sensor networks. Das et al. claimed that their scheme is effectively secure against the various security flaws. In this paper, author will prove that Das et al.'s scheme is still vulnerable to man-in-the-middle attack, password guessing/change attack and does not support mutual authentication between the user and the cluster heads.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.744-749
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• 2013

The protection switching technology is widely adopted in the fiber-optical transmission equipments based on TDM(Time Division Multiplexing), such as PDH, SDH/SONET. A variety of protection switching algorithms for Ethernet networks and the progress of standardization are summarized in the document. There are several kinds of protection switching algorithms for Ethernet networks, such as STP, RSTP, MSTP and etc. However, since Ethernet signal move through detour route, it causes much time to recover. Accordingly, it is difficult to secure a usability of Ethernet networks and QOS(Quality of Service). Also, if the protection switching protocol standardized by IEEE and ITU-T is used, it remains a inherent network switching time for protection. Therefore, a specific protection switching algorithm for Ethernet are needed for seamless and stable operation of Ethernet networks service for Distribution Automation System(DAS). A reliable protection algorithm with no switching delay time is very important to implement Self-healing service for DAS. This study of FPGA based protection switching algorithm for Ethernet networks shows that in case of faults occurrence on distribution power network, immediate fault isolation and restoration are conducted through interaction with distribution equipments using P2P(Peer to Peer) communication for protection coordination. It is concluded that FPGA based protection switching algorithm for Ethernet networks available 0ms switching time is crucial technology to secure reliability of DAS.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.422_423
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• 2009

DNP 3.0 is the most widely used data communication protocol for electric power control systems. KEPCO(Korea Electric Power Corporation) also uses DNP 3.0 as a data transmission protocol for the DAS(Distribution Automation System) and the SCADA system of the transmmission system. But DNP 3.0 is one of the oldest industrial standard having many restrictions and there are many considerations for optimal design of DNP 3.0 network for the Distribution Automation System.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.354-362
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• 2008

In this paper, a new algorithm of optimal voltage control is proposed for the Distribution Automation System (DAS) based on constants of four terminal network modeling. In the proposed method, the voltage profiles along feeders are estimated from the measurement of the current and power factor by a Feeder Remote Terminal Unit (FRTU) installed at each node. Whenever the voltage profile violates the restriction, the voltage control strategy is applied to keep the voltage levels along the feeders within the pre-specified range through the modification and coordination of the transformer under-load tap changers (ULTC), step voltage regulator (SVR), as well as shunt condenser. In the case studies, the estimation and control of the voltages have been testified in a radial distribution system with 11 nodes.