• The KSFM Journal of Fluid Machinery
• /
• v.14 no.6
• /
• pp.26-34
• /
• 2011

Waterhammer and slamming phenomena can occur when power is cut off due to reversal flow in pipeline and sudden close of check valve. Therefore analysis of reversal flow time, which means the time of reversal flow in pipeline due to pumping station blackout, is needed to protect facilities from waterhammer economically and efficiently. However systematic study on reversal flow time has not been done yet. So theory of reversal flow time analysis is proposed and verified with experiment using several parameters like pump specific speed, motor pole number, and characteristic curve of pipeline in this study.

• Nuclear Engineering and Technology
• /
• v.47 no.6
• /
• pp.719-728
• /
• 2015

Following the Fukushima accident, a special safety inspection was conducted in Korea. The inspection results show that Korean nuclear power plants have no imminent risk for expected maximum potential earthquake or coastal flooding. However long- and short-term safety improvements do need to be implemented. One of the measures to increase the mitigation capability during a prolonged station blackout (SBO) accident is installing injection flow paths to provide emergency cooling water of external sources using fire engines to the steam generators or reactor cooling systems. This paper illustrates an evaluation of the effectiveness of external cooling water injection strategies using fire trucks during a potential extended SBO accident in a 1,000 MWe pressurized water reactor. With regard to the effectiveness of external cooling water injection strategies using fire engines, the strategies are judged to be very feasible for a long-term SBO, but are not likely to be effective for a short-term SBO.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.3
• /
• pp.235-241
• /
• 2020

In this paper, we propose the bus/bypass synchronization phase lock loop (B-Sync PLL) method using each phase voltage controller of a parallel UPS inverter. The B-Sync PLL included in each phase voltage control system of parallel UPS inverters has the transient response and the phase synchronization error at grid normal or blackout. The validity of this method is verified by simulation and experiment. As a result, the parallel UPS inverters using the proposed method confirmed that the output phase was continuously synchronized when a grid blackout, improving the transient response characteristics for stable load power supply and equal load sharing.

• Nuclear Engineering and Technology
• /
• v.28 no.3
• /
• pp.247-256
• /
• 1996

This paper presents a new approach for assessing accident management strategies using containment event trees (CETs) developed during an individual plant examination (IPE) for a reference plant (CE type, 950 MWe PWR). Various accident management strategies to reduce risk have been proposed through IPE. Three strategies for the station blackout sequence are used as an example : 1) reactor cavity flooding only, 2) primary system depressurization only, and 3) doing both. These strategies are assumed to be initiated at about the time of core uncovery. The station blackout (SBO) sequence is selected in this paper since it is identified as one of the most threatening sequences to safety of the reference plant. The effectiveness and adverse effects of each accident management strategy are considered synthetically in the CETs. A best estimate assessment for the developed CETs using data obtained from NUREG-1150, other PRA results, and the MAAP code calculations is performed. The strategies are ranked with respect to minimizing the frequencies of Various containment failure modes. The proposed approach is demonstrated to be very flexible in that it can be applied to any kind of accident management strategy for any sequence.

• Cross-Cultural Studies
• /
• v.20
• /
• pp.225-240
• /
• 2010

Soon after joining the Canadian Confederation in 1867, the province of Quebec adopted the phrase Je me souviens ("As I recall") as its 'national' motto, although many Qu?b?cois do not remember today what they were supposed to memorize, as collective subject, when their government voted this motion. My thesis is that contrary to other countries which have a strong sense of history based on a secular tradition, this process was more complicated in Quebec - as if a collective memory loss lied at the heart of it's history. Through a rereading of Hubert Aquin's cult novel, Trou de m?moire (in its English translation Blackout), first published in 1968, I try to illustrate this paradox and to emphasize the heuristic functions of memory blanks, gaps and lapses in certain postmodern narratives, after the historical breakdown of "the great narratives" (Lyotard). In this perspective, the example of Quebec, through the voice of one of its more gifted yet controversial novelist, can be seen as emblematic of what happens when the mnemonic impossibility of rewriting history opens up new possibilities for writing fiction.

• Journal of information and communication convergence engineering
• /
• v.21 no.1
• /
• pp.62-67
• /
• 2023

This paper proposes an imputation method using a bidirectional k-nearest components search based local linear regression method. The bidirectional k-nearest-components search method selects components in the dynamic range from the missing points. Unlike the existing methods, which use a fixed-size window, the proposed method can flexibly select adjacent components in an imputation problem. The weight values assigned to the components around the missing points are calculated using local linear regression. The local linear regression method is free from the rank problem in a matrix of dependent variables. In addition, it can calculate the weight values that reflect the data flow in a specific environment, such as a blackout. The original missing values were estimated from a linear combination of the components and their weights. Finally, the estimated value imputes the missing values. In the experimental results, the proposed method outperformed the existing methods when the error between the original data and imputation data was measured using MAE and RMSE.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.05a
• /
• pp.467-467
• /
• 1999

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.05a
• /
• pp.174.1-174.1
• /
• 2004

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.10a
• /
• pp.209.2-209
• /
• 2002

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.1
• /
• pp.86-91
• /
• 2014

In the field of shipbuilding and marine, electrical power system is that each of the distributed bus bars is connected electrically. In this way, it would be appropriate to recognize as grid-connecting rather than the redundant bus. Short-circuit capacity of the electric power system will be increased proportionally which is due to the addition of the bus. The increase of short-circuit capacity needs high initial cost associated with equipment and can generate the blackout when the equipment with a physically connected to the bus occurs the electric failure. In order to solve these problems, marine electrical power system in which current limiting reactor has been applied is classified according to the network topology, bus network, star network and ring network. And short circuit analysis for each network is performed by the fault types. The results are presented pros and cons compared to each other.