• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.585-594
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• 2011

This paper presents the use of sequential outage checkers to identify the potential cascading processes that might lead to large blackouts. In order to analyze cascading outages caused by a combination of thermal overloads, low voltages, and under-frequencies following an initial disturbance, sequential outage checkers are proposed. The proposed sequential outage checkers are verified using the AEP 9-bus system, New England 39-bus system, and IEEE 118-bus system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.9
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• pp.821-827
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• 2015

Electromagnetic waves which are emitted from the Sun due to solar flare explosion can cause failures in HF radio communications in the day-side area of the Earth, that is so-call as Radio Blackouts. The international scale representing the severity of the Radio Blackouts is determined by the solar X-ray flux which is measured by United States Geostationary Operational Environmental Satellite. However, the scale is not always applicable to HF communication users in the different area on the Earth, because the HF communication effects depend not only on the X-ray strength but also on the subsolar point location. To solve this problem, we developed a HF radio spectrum monitoring system utilizing a spectrum analyzer. This system conducts a real-time measure of the HF spectrum, and automatically calculates signal to noise ratios and the occurrences of the HF blackouts as comparing with the interference level which is described from the ITU recommendation.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.34-35
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• 2006

This paper presents an information collection and a novel inference technique for evaluation of power system operation state. In most developing countries, power demands are steadily increasing and consequently power systems are becoming larger and more complicated. In addition, power system deregulations further complicate the power system operational tasks, which are resulted in prevailing wide area blackouts worldwide. In this paper, we proposed an effective information collection and operating state evaluation methods using a knowledge-based system. The RTS-79 24 bus system is used as a test system. The power system model is composed with JESS templates and included in the knowledge-base as a part of fixed facts. Dynamic informations are collected from various analysis results and actual operational data. Inferences are performed with rules expressed with terms in different abstraction levels. Future research will be concentrated on intelligent contingency selections for preventing wide area blackouts.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1347-1353
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• 2011

While most of the existing protection schemes have been designed with local information around individual components, these local schemes are not considered capable of protecting the modern electric power gird with growing complexity. Recent blackouts in North America and Europe have renewed the emphasis on coordinated protection and control actions to avoid systemwide blackouts, utilizing all of the available grid information. Thus, this paper proposes a new methodology, Agent-based Colored Petri Net (ACPN) modeling for systematically representing, modeling and analyzing information flows and interactions among the entities of the electric power grid. The paper demonstrates its efficacy and accuracy by investigating an ACPN model of a wide area protection system for a typical power grid. The proposed modeling and analysis schemes may further provide a framework to help assure reliability and interoperability of diverse smart grid components.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.103-108
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• 2005

Catastrophic failures in power systems are rare but not uncommon events. Protection systems play an important role in the progression of events during a catastrophic failure. This paper will examine some of the historical records, and suggest possible improvements to protection systems which can have a positive impact on power system performance during catastrophic failures.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.13-17
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• 2018

According to the recent blackouts, large blackouts can be described by cascading outages. Cascading outage is defined by sequential outages from an initial disturbance. Sequential and probabilistic approach are necessary to minimize the blackout damage caused by cascading outages. In addition, conventional cascading outage analysis models are computationally complex and have time constraints, it is necessary to develop the new analytical techniques. In this paper, we propose the advance visualization model for probabilistic analysis of cascading failure risks. We introduce the visualization model for identifying size of cascading and potential outages and estimate the propagation rate of sequential outage simulation. The proposed model is applied to Korean power systems.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.60-61
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• 2006

An unwanted trip of backup distance relays often lead to a blackout. This paper presents investigation report on involvement of backup distance relays in the past blackouts and sensitivity-factor based algorithm to make a distinction between a fault and overload caused by line tripping. A preliminary idea to prevent deterioration of the situation due to unwanted trip of distance relays by utilizing the proposed algorithm is presented.

• Biomolecules & Therapeutics
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• v.24 no.4
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• pp.433-437
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• 2016

Consumption of high doses of ethanol can lead to amnesia, which often manifests as a blackout. These blackouts experienced by ethanol consumers may be a major cause of the social problems associated with excess ethanol consumption. However, there is currently no established treatment for preventing these ethanol-induced blackouts. In this study, we tested the ethanol extract of the roots of Salvia miltiorrhiza (SM) for its ability to mitigate ethanol-induced behavioral and synaptic deficits. To test behavioral deficits, an object recognition test was conducted in mouse. In this test, ethanol (1 g/kg, i.p.) impaired object recognition memory, but SM (200 mg/kg) prevented this impairment. To evaluate synaptic deficits, NMDA receptor-mediated excitatory postsynaptic potential (EPSP) and long-term potentiation (LTP) in the mouse hippocampal slices were tested, as they are known to be vulnerable to ethanol and are associated with ethanol-induced amnesia. SM (10 and $100{\mu}g/ml$) significantly ameliorated ethanol-induced long-term potentiation and NMDA receptor-mediated EPSP deficits in the hippocampal slices. Therefore, these results suggest that SM prevents ethanol-induced amnesia by protecting the hippocampus from NMDA receptor-mediated synaptic transmission and synaptic plasticity deficits induced by ethanol.

• Journal of Preventive Medicine and Public Health
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• v.48 no.3
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• pp.142-150
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• 2015

Objectives: The purpose of this study was to investigate the association between suicidal behavior and patterns of alcohol consumption in Korean adults. Methods: This study was based on data provided by the Korea National Health and Nutritional Examination Survey from 2007 to 2011. A total of 42 347 subjects were included in the study, of whom 19 292 were male and 23 055 were female. Logistic regression analysis was performed to assess the association between patterns of alcohol consumption and suicidal behavior. Results: Among the study subjects, 1426 males (11.3%) and 3599 females (21.2%) had experienced suicidal ideation, and 106 males (0.8%) and 190 females (1.1%) had attempted suicide during the previous 12 months. Alcohol Use Disorders Identification Test (AU-DIT) scores were found to be associated with suicidal ideation in males and associated with both suicidal ideation and suicide attempts in females. Alcoholic blackouts were associated with suicidal ideation and suicide attempts in males, and were also associated with suicidal ideation in females. Conclusions: In this study, we found that certain patterns of alcohol consumption were associated with suicidal behaviors. In particular, only alcoholic blackouts and categorized AUDIT scores were found to be associated with suicidal behavior in males. We therefore suggest that further research is needed to examine this relationship prospectively and in other settings.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.274-275
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• 2011

Fault current problems is considered a serious issue in the power system because large fault currents not only cause many side effects to the equipments of power system but also lead to severe problems, such as blackouts. This paper deals with the structural analysis and 3-phase fault current stability of the future Seoul metropolitan power system. The simulation composition and analysis are performed with the 4th KEPCO power supply planning data using PSS/e. Through the results of the simulations, it can be observed that the future Seoul metropolitan system results in a fault current which exceeds the circuit breaker (CB) rate. This unremovable fault current can cause critical damage to power system. To resolve the problem, the algorithm for the application of Voltage Sourced Converter Back-to-Back High Voltage Direct Current (VSC BTB HVDC) is being proposed. where the most suitable location for solving fault current problem in Seoul metropolitan area is being implemented.