• Journal of Electrical Engineering and Technology
• /
• 제1권3호
• /
• pp.295-301
• /
• 2006

This paper presents a new two-terminal numerical algorithm for fault location estimation using the synchronized phasor in time-domain. The proposed algorithm is also based on the synchronized voltage and current phasor measured from the PMUs (Phasor Measurement Units) installed at both ends of the transmission lines. In this paper, the algorithm is given without shunt capacitance and with shunt capacitance using II -model and estimated using DFT (Discrete Fourier Transform) and LES (Least Error Squares Method). The algorithm uses a very short data window and classification for real-time transmission line protection. To verify the validity of the proposed algorithm, the Electro-Magnetic Transient Program (EMTP) and MATLAB are used.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
• /
• pp.281-284
• /
• 2004

This paper presents the design and implementation of a QoS based enhanced collaboration system in MDO. This is an efficient distributed communication tool between designers. It supports text communication, audio/video communication, file transfer and XML data sending/receiving. Specially, this system supports a dynamic QoS self-adaptation by using the improved direct adjustment algorithm (DAA+). The original direct adjustment algorithm adjusts the transmission rate according to the congestion level of the network, based on the end to end real time transport protocol (RTP), and controls the transmission rate by using the information of loss ratio in real time transport control protocol (RTCP). But the direct adjustment algorithm does not consider when the RTCP packets are lost. We suggest an improved direct adjustment algorithm to solve this problem. We apply our improved direct adjustment algorithm to our of QoS (Quality of Service) [1] based collaboration system and show the improved performance of transmission rate and loss ratio.

• Journal of Electrical Engineering and Technology
• /
• 제13권6호
• /
• pp.2212-2219
• /
• 2018

This paper describes extended fault location algorithm using estimated remote source impedance. The method uses data only at the local end and the sequence current distribution factors for more accurate estimation. The proposed algorithm can respond to variation of the local and remote source impedance. Therefore, this method is especially useful for transmission lines interconnected to a wind farm that the source impedance varies continuously. The proposed algorithm is very insensitive to the variation in fault distance and fault resistance. The simulation results have shown the accuracy and effectiveness of the proposed algorithm.

• 한국통신학회논문지
• /
• 제27권6B호
• /
• pp.586-592
• /
• 2002

본 논문에서는 이동 접속망에서 발생하는 지연시간을 줄이기 위해 AMC/TDM 무선 데이터 통신에 적합한 새로운 스케줄러 알고리즘을 제안하였다. 새로이 제안된 알고리즘은 비례공정(Proportional fairness) 알고리즘과 M-LWDF(Modified Largest Weighted Delay First) 알고리즘에 기초를 하면서, Xin Liu에 의해 제안된 최소성능보장 알고리즘의 개념을 응용하여 제안되었다. 제안된 알고리즘은 best-effort 서비스뿐만 아니라, QoS 보장서비스에도 적용 가능한 알고리즘으로, 모의실험결과 본 논문에 의해 새로이 제안된 알고리즘을 적용하였을 경우 기존의 비례공정알고리즘이나, M-LWDF알고리즘에 비해 각각 최대 11.5%와 9%의 전송 지연시간을 줄일 수 있었다.

• 한국통신학회논문지
• /
• 제27권2A호
• /
• pp.146-156
• /
• 2002

This paper presents an adaptive H.263+ rate control algorithm for streaming video applications under the networks supporting bandwidth renegotiation, which can communicate with end-users to accommodate their time-varying bandwidth requests during the data transmission. That is, the requests of end-users can be supported adaptively according to the availability of the network resources, and thus the overall network utilization can be improved simultaneously. They are especially suitable for the transmission of non-stationary video traffics. The proposed rate control algorithm communicates with the network to renegotiate the required bandwidth fort the underlying video which are measured based on the motion change information, and choose their control strategies according to the renegotiation results. Unlike most conventional algorithms that control only the spatial quality by adjusting quantization parameters, the proposed algorithm treats both the spatial and temporal qualities at the same time to enhance human visual perceptual quality. Experimental results are provided to demonstrate that the proposed rate control algorithm can achieve superior performance to the conventional ones with low computational complexity under the networks supporting bandwidth renegotiation.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2198-2202
• /
• 2003

The data transmission of MVB(Multifunction Vehicle Bus) of TCN(Train Network Communication) is divided into the periodic transmission phase and the sporadic transmission phase. TCN standard defines the event-polling method for the message transfer in the sporadic phase. However, since the event-polling method does not use pre-scheduling to the priority of the messages to be transmitted, it is inefficient for the real-time systems. To schedule message transmission, a master node should know the priority of message to be transmitted by a slave node prior to the scheduling the sporadic phase, but the existing TCN standard does not support any protocol for this. This paper proposes the slave frame bit-stuffing algorithm, with which a master node gets the necessary information for transmission scheduling and includes the simulation results of the event-polling method and the proposed algorithm.

• Journal of Electrical Engineering and Technology
• /
• 제12권5호
• /
• pp.1798-1804
• /
• 2017

This paper presents an approach of the Gustafson-Kessel (GK) clustering algorithm's performance in fault identification on power transmission lines. The clustering algorithm is incorporated in a scheme that uses hybrid intelligent technique to combine artificial neural network and a fuzzy inference system, known as adaptive neuro-fuzzy inference system (ANFIS). The scheme is used to identify the type of fault that occurs on a power transmission line, either single line to ground, double line, double line to ground or three phase. The scheme is also capable an analyzing the fault location without information on line parameters. The range of error estimation is within 0.10 to 0.85 relative to five values of fault resistances. This paper also presents the performance of the GK clustering algorithm compared to fuzzy clustering means (FCM), which is particularly implemented in structuring a data. Results show that the GK algorithm may be implemented in fault identification on power system transmission and performs better than FCM.

• 전기학회논문지
• /
• 제65권6호
• /
• pp.955-961
• /
• 2016

Fault location estimation is an important element for rapid recovery of power system when fault occur in transmission line. In order to calculate line impedance, most of fault location algorithm uses by measuring relaying waveform using DFT. So if there is a calculation error due to the influence of phasor by DC offset component, due to large vibration by line impedance computation, abnormal and non-operation of fault locator can be issue. It is very important to implement the robust fault location algorithm that is not affected by DC offset component. This paper describes an enhanced fault location algorithm based on the DC offset elimination filter to minimize the effects of DC offset on a long transmission line. The proposed DC offset elimination filter has not need any erstwhile information. The phase angle delay of the proposed DC offset filter did not occurred and the gain error was not found. The enhanced fault location algorithm uses DFT filter as well as the proposed DC offset filter. The behavior of the proposed fault location algorithm using off-line simulation has been verified by data about several fault conditions generated by the ATP simulation program.

• 조명전기설비학회논문지
• /
• 제30권1호
• /
• pp.28-37
• /
• 2016

Fault locating is an important element to minimize the damage of power system. The computation error of fault locator may occur by the influence of the DC offset component during phasor extraction. In order to minimize the bad effects of DC offset component, this paper presents an improved fault location algorithm based on a DC offset removal filter for short fault in a double circuit transmission line. We have modeled a 154kV double circuit transmission line by the ATP software to demonstrate the effectiveness of the proposed fault locating algorithm. The line to line short faults were simulated and then collected simulation data was used. It can be seen that the error rate of fault locating estimation by the proposed algorithm decreases than the error rate of fault locating estimation by conventional algorithm.

• Journal of information and communication convergence engineering
• /
• 제10권4호
• /
• pp.365-371
• /
• 2012

In recent years, researchers have been attracted to clustering methods to improve communication and data transmission in a network. Compared with traditional wireless networks, wireless sensor networks are energy constrained and have lower data rates. The concept of implementing a clustering algorithm in an existing project on gateway relocation is being explored here. Low energy adaptive clustering hierarchy (LEACH) is applied to an existing study on relocating a gateway. The study is further improved by moving the gateway to a specific cluster based on the number or significance of the events detected. The protocol is improved so that each cluster head can communicate with a mobile gateway. The cluster heads are the only nodes that can communicate with the mobile gateway when it (the mobile gateway) is out of the cluster nodes' transmission range. Once the gateway is in range, the nodes will begin their transmission of real-time data. This alleviates the load of the nodes that would be located closest to the gateway if it were static.