• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2565-2571
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• 2020

Background: Understanding the behaviour of nuclear fuel claddings by conducting burst test on single cladding tube under simulated loss-of-coolant accident conditions and developing theoretical cum empirical predictive computer codes have been the focus of several investigations. The developed burst criterion (a) assumes symmetrical deformation of cladding tube in contrast to experimental observation (b) interpolates the properties of Zircaloy-4 cladding in mixed α+β phase (c) does not account for azimuthal temperature variations. In order to overcome all these drawbacks of burst criterion, it is reasoned that artificial intelligence technique may be a better option to predict the burst parameters. Methods: Artificial neural network models based on feedforward backpropagation algorithm with logsig transfer function are developed. Results: Neural network architecture of 2-4-4-3, that is model with two hidden layers having four nodes in each layer is found to be the most suitable. The mean, maximum, and minimum prediction errors for this optimised model are 0.82%, 19.62%, and 0.004%, respectively. Conclusion: The burst stress, burst temperature, and burst strain obtained from burst criterion have average deviation of 19%, 12%, and 53% respectively whereas the developed neural network model predicted these parameters with average deviation of 6%, 2%, and 8%, respectively.

• Geomechanics and Engineering
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• v.24 no.3
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• pp.205-213
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• 2021

Water infusion has long been taken as an effective way to eliminate coal burst risk as coal properties can be loosen and soften by water infusion. However, not all industrial trials of water infusion for coal burst prevention have been necessarily effective in all situations as the effectiveness of this method can be affected by water infusion time, coal properties and the parameters of water injection. Hence, some fundamental issues including the effects of water infusion time on burst propensity and energy evolution need to be further discussed. In this paper, four groups of coal specimens with 0 day, 5 days, 10 days, and 15 days water saturation time are tested under uniaxial compression load with the application of AE monitoring. To comprehensively compare the burst behavior of coal specimens under different water saturation time, stress-strain curves, AE counts, fragmentation characteristics and burst propensity of these groups are analyzed. It was found by this research that sufficient water saturation can mitigate the burst behavior of coal samples while insufficient water infusion might cannot reach the burst mitigation aims.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.56-63
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• 2014

In this research, burst tests for axial notched steam generator tubes were conducted. To measure the burst pressure of notched tubes, a burst testing system was manufactured. The tests were conducted under internal pressure at room temperature. Part-through-wall and through-wall notches which have various geometries with different depths and lengths were machined by electro-discharged-machined(EDM) method. The burst pressure decreased exponentially with increasing notch length and decreased almost linearly with increasing notch depth. A comparison of the burst pressure with existing burst pressure solutions for cracked tube show that the existing solution agree well with the test results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1138-1147
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• 2012

In this paper, an efficient power control based MF-TDMA resource allocation scheme is proposed for next generation military satellite communication systems. The proposed scheme has the flexibility is used to support heterogeneous terminals with differ in transmission capabilities. The method can be divided into two parts : burst size calculation and burst structure determination. At first, we estimate the link budget taken into account a dynamic satellite link state variation. Then, applicable ACM level and burst size is chosen. In burst structure determination phase, we reorganize the burst structure in time-frequency domain by controlling limited power, bandwidth, time resources. In particular, we compensate the power spectral density among different terminals to integrate them in same transponder, Furthermore, we increase the packing efficiency by controlling the ACM level of the burst in applicable power spectral density range. Simulation results show that the method increase the spectral efficiency and burst packing efficiency. In addition, slot allocation rejection ratio is successfully reduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.291-298
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• 2016

In this paper, we studied about the radiated emission of EFT(Electrical Fast Transient)/Burst signal, referenced IEC-61000-4-4 of the international EMC standard and its effect on EUT(Equipment Under the Test) when EFT/Burst signal (Conducted noise) induced on a power cable to EUT. Firstly, we set up test sample by the standard and +4 kV standard signal is induced by EFT/Burst signal generator with 1 m length power cable for 1 minute. Consequently, we found not only induced EFT/Burst signal along power line, but also directly radiated emission signal from EFT/Burst signal generator (Radiated emission noise of EFT/Burst). The radiated emission signal of EFT/Burst was 30 dB which is higher than limit of CISPR 22 which is international EMC standard. Moreover, we measured the electric field strength by changing distance from maximum radiated emission point to electric field strength tester. As a result, this electric field strength was 23 V/m which is higher than international EMC standard test level(CISPR 24). Therefore, it was confirmed that the probability of malfunction may be high when radiated emission of EFT/Burst noise exists near the EUT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.41-51
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• 2004

Operation and maintenance (OAM) in optical burst switching (OBS) networks has not yet been addressed even though OBS has been gaining research interest in recent years. In this paper, we defined five OBS functions such as Burst Termination (BT), Burst Transmission (BTX), Burst Switching (BSW), Routing and Switching Control (RSC), and Protection and Restoration (PAR). A functional model for OBS networks and an OAM architecture are designed to meet the operational requirements. We present the first framework to realize OAM in OBS networks, including OAM activities, OAM-capable OBS nodes such as ingress edge, core, and egress edge nodes, OAM information and communication models and protocols. A number of examples of possible network failures are pointed out and the corresponding reactions to these using the proposed OAM architecture are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.72-84
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• 2005

Optical burst switching networks usually employ one-way reservation by sending a burst control packet with a specific offset time, before transmitting each data burst Same. Due to such a Property, burst-contentions occur when multiple bursts contend for the same wavelength in the same output link simultaneously in a node, leading to burst losses, eventually degrading the quality of service. Therefore, in this paper, we propose a dynamic routing algorithm using minimum local state information in order to decrease burst-contentions. In this proposed scheme, if burst loss rate exceeds a threshold value at a certain node, a new alternative routing path is chosen according to burst priority and location of burst generation, which enables the contending bursts to detour around the congested link. Moreover, for reducing the effect of sending bursts on the primary path due to the alternative path, we also apply a minimum path-cost based routing on link-cost concept. Our simulation results show that proposed scheme improves the network performance in terms of burst loss probability and throughput by comparing with conventional one.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.1
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• pp.76-83
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• 2000

A measurement technique of a sea height of burst is introduced for a proximate test using the image recognition of video cameras. In the burst of fuse on the ocean, the burst center of fuse, the sea surface level and the height of calibration poles are measured by the process of image obtained from cameras. Finally, the height of burst of fuse can be computed by Hough transform algorithm. The error compensation algorithms are proposed to eliminate the errors caused by camera level and environmental parameters. As a result of experiment, it has been proved that the proposed measurement system shows the recognition of the center point of the burst image with ${\pm}$0.5m error.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.177-180
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• 2000

Optical burst switching(OBS) is a new switching paradigm to supporting bursty traffic on the Internet efficiently. OBS separates burst level and control level. To handle data burst efficiently, the scheduling schemes in optical burst switching systems must keep track of future resource availability when assigning arriving data bursts to wavelength channels. In this paper, we evaluate the performance of three scheduling schemes which are called Horizon, Single-gap and Multiple-gap, as a basic study for the future research of Optical Internet. Thus, firstly, we analyze the trade-off between the performance and the processing overhead of each scheme. In addition, the performance of OBS system which uses Multiple-gap scheduling is evaluated in detail under various network size. We use simulation for performance evaluation in terms of burst loss rate(BLR), wavelength channel utilization and the number of management data.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2047-2053
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• 2020

Single-tube burst tests on hydrogenated Zircaloy-4 nuclear fuel cladding under simulated loss-of-coolant accident are conducted to evaluate the impact of hydrogen on burst parameters. The heating rate and initial pressure are varied from 5 K/s to 150 K/s and 5 bar-80 bar, respectively. The hydrogen concentration in the cladding is in the range of 0-2000 wppm. Burst stress is lower for hydrogenated cladding in α-phase. A significant loss of ductility is observed in α-phase and lower α + β-phase for hydrogenated cladding. However, the burst strain is higher for hydrogenated cladding in β-phase. There is a sigmoidal dependency of rupture area with initial stress and rupture area is larger for hydrogenated cladding. A novel burst stress correlation for hydrogenated Zircaloy-4 cladding has been proposed.