• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.438-445
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• 2004

This paper presents a new numerical spectral domain algorithm devoted to blocking unsuccessful automatic reclosing onto permanent faults and fault distance calculation. Arc voltage amplitude and fault distance are calculated from the fundamental and third harmonics of the terminal voltages and currents phasors. From the calculated arc voltage amplitude it can be concluded if the fault is transient arcing fault or permanent arcless fault. If the fault is permanent automatic reclosure should be blocked. The algorithm can be applied for adaptive autoreclosure, distance protection, and fault location. The results of algorithm testing through computer simulation and real field record are given.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.808-810
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• 1996

In this paper, neural network, which has learning capability, is used for fault type classification and fault section estimation for high speed relaying. The potential of the neural network approach is demonstrated by simulation using ATP. The instantaneous values of voltages and currents are used the inputs of neural networks. This approach determines the fault section directly. In this paper, back-propagation network(BPN) is used for fault type classification and fault section estimation and can use for high speed relaying because it determines fault section within a few msec.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.26-28
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• 2004

The primary role of ZnO arresters is to protect transmission and distribution equipments against lightning surges. The extremely nonlinear V-I characteristics of the ZnO arrester obviates the need for isolation gaps and consequently it is continuously connected to line voltage. For this reason, ZnO arresters are degraded with time in actual power systems. In this work, the characteristics of the luminous events caused between the ZnO block and electrodes according to the electrode area were investigated. As a result, the luminous events were effected by electrode area and the longer electrode areas were increased, the more luminous events were decreased. Also the reduction of luminous events was fumed up to the degraded ZnO arrester block.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.103-105
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• 1996

This paper describes real time dynamic tests on the digital distance relay using new digital test system including RTDS(Real Time Digital Simulator) in KEPRI. The RTDS is developed by the Manitoba HVDC Research Centre and consists of specialized hardware and software which allows transients simulation of electrical power systems in real time. From high impedance fault test, it is known that the characteristics of distance reach is influenced by load flow. A detailed discussion of relay test using the RTDS simulator, high impedance faults and test results are included in the paper.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.444-450
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• 2008

There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the $8/20{\mu}s$ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.169-171
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• 2004

Available transfer capability(ATC) is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading in power transaction activities. This paper deals with an application of optimization technique for available transfer capability(ATC) calculation and analyzes the results of ATC by considering several constraints. Sequential quadratic programming(SQP) is used to calculate the ATC problem with state-steady security constraints. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.65.6-65
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• 2001

The satellite communication has been widely applied in the various fields included the remote monitoring and control system through the technical progress. In the star network that is a type of the satellite communication network, users can easily use an earth station because of the large scale and high power of the hub station. This type has many profits which are flexible of network configuration, and can conveniently and inexpensively supply various services which is used in the data acquisition and distribution by important communication means for construction of information society. Using these profits, the satellite communication system is applied to the unmaned remote operation field for the remote control and monitor of the water treatment plants But, ...

• Proceedings of the KIEE Conference
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• summer
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• pp.183-185
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• 2004

This paper deals with an application of optimization technique for available transfer capability(ATC) calculation. ATC is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading. Sequential quadratic programming(SQP) is used to calculate the ATC problem with state-steady security constraints. The proposed method is applied to 10 machines 39 buses model systems. The results are discussed and compared to those obtained by continuation power flow(CPF).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1082-1086
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• 2008

Multiple-input multiple-output (MIMO) is an efficient technology to increase data rate in wireless networks due to bandwidth and power limitations. Data transmission rate between transmitter and receiver is determined by channel capacity. MIMO has an advantage of reliable communication over wireless channel because of utilizing the channel capacity properly. In this letter, we drive a new formula, closed form capacity formula, using confluent hypergeometric function.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.365-382
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• 2021

This paper proposes a novel two-way relaying (TWR) approach for a two-relay wireless network based on non-orthogonal multiple access (NOMA), where two terminals exchange messages with a cellular base station (BS) via two intermediate relay stations (RSs). We propose a NOMA-based TWR approach with two relaying schemes, i.e., amplify-and-forward (AF) and decode-and-forward (DF), referred to as NOMA-AF and NOMA-DF. The sum-rate performance of our proposed NOMA-AF and NOMA-DF is analyzed. A closed-form sum-rate upper bound for the NOMA-AF is obtained, and the exact ergodic sum-rate of NOMA-DF is also derived. The asymptotic sum-rate of NOMA-AF and NOMA-DF is also analyzed. Simulation results show that the proposed scheme outperforms conventional orthogonal multiple access based transmission schemes. It is also shown that increasing the transmit power budget of the relays only cannot always improve the sum-rates.