• Korean Journal of Culture and Social Issue
• /
• v.21 no.3
• /
• pp.419-455
• /
• 2015

In study I, Domain-Specific Risk Taking Scale(DOSPERT) was translated into Korean and was validated that it had 6 factors structure and showed adequate reliability and validity, using the data had been collected from 438 participants. In study 2, two research problems were examined using the data had been collected from 497 participants who were different from study I. First, the mediation effect of sensation seeking and perceived benefit on the relationship between narcissism and risk-taking were examined. Using path analysis, it found that sensation seeking and perceived benefit mediated the relationship between NPI narcissism and risk-taking fully, and between PNI narcissism and risk-taking partially. Seceond, the moderate effect of contingencies of self-worth(CSW) on the relationship between perceived benefit-risk and risk-taking was examined. Using multi-group analysis, it found that virtue CSW moderated the relationship between perceived benefit-risk and total risk-taking, various CSWs moderated the relationships between perceived benefit-risk and 6 sub domains of risk-taking. These results were compared with previous studies of risk-taking and discussed the relevance of the narcissistic type.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.1
• /
• pp.18-29
• /
• 2015

State Estimation (SE) is the basis of a variety of advanced applications used in most modern power systems. An SE problem formed with enough phasor measurement units (PMUs) data is simply a linear weighted least squares problem requiring no iterations. Thus, designing a minimum-cost placement of PMUs that guarantees observability of a power system becomes a worthy challenge. This paper proposes an equivalent integer linear programming method for substation-oriented optimal PMU placement (SOOPP). The proposed method uses an exhaustive search to determine a globally optimal solution representing the best PMU placement for that particular power system. To obtain a more comprehensive model, contingencies and the limitation of the number of PMU measurement channels are considered and embodied in the model as changes to the original constraints and as additional constraints. The proposed method is examined for applicability using the IEEE 14-bus, 118-bus and 300-bus test systems. The comparison between SOOPP results and results obtained by other methods reveals the excellence of SOOPP. Furthermore, practical large-scale power systems are also successfully analyzed using SOOPP.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.541-548
• /
• 2017

An increasing concern is paid to short-term voltage stability with the growth of penetration of induction motor loads. Reactive power reserve(RPR) of power system is critical to improve voltage stability. A definition of short-term voltage stability-related RPR(SVRPR) is proposed. Generators vary their contributions to voltage stability with their location and system condition, etc. Voltage support coefficient based on the second-order trace sensitivity method is proposed to evaluate SVRPR's contribution to short-term voltage stability. The evaluation method can account for the generator's reactive support in transient process and the contingency severity. Then an optimization model to improve short-term voltage stability is built. To deal with multiple contingencies, contingency weight taking into account both its probability and severity is proposed. The optimization problem is solved by primal dual interior point method. Testing on IEEE_39 bus system, it is indicated that the method proposed is effective. Short-term voltage stability is improved significantly by the way of SVRPR optimization. Hence, the approach can be used to prevent the happening of voltage collapse during system's contingency.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2002.02a
• /
• pp.285-290
• /
• 2002

Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such short circuits are increasing higher. The Maximum short circuit current of modern power system is becoming so large that circuit breaker are not expected th be able to shut down the current in the future. In order to cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for future power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element(resistor or reactor). The introduction merits of the SFCL were investigated quantitatively by RTDS/EMTDC from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparison characteristics for two type SFCL. Desired design specification and operation parameters of SFCL were also given qualitatively by the performance evaluation of the two type SFCL in the power system.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.4
• /
• pp.484-492
• /
• 2011

Power system analyses, which involve the handling of massive data volumes, necessitate the use of effective visualization methods to facilitate analysis and assist the user in obtaining a clear understanding of the present state of the system. This paper introduces an interface that compensates for the limitations of the visualization modules of dynamic security assessment tools, such as PSS/e and TSAT, for power system variables including generator rotor angle and frequency. The compensation is made possible through the automatic provision of dynamic simulation data in visualized and tabular form for better data intuition, thereby considerably reducing the redundant manual operation and time required for data analysis. The interface also determines whether the generators are stable through a generator instability algorithm that scans simulation data and checks for an increase in swing or divergence. The proposed visualization methods are applied to the dynamic simulation results for contingencies in the Korean Electric Power Corporation system, and have been tested by power system researchers to verify the effectiveness of the data visualization interface.

• Journal of Korea Multimedia Society
• /
• v.5 no.3
• /
• pp.323-330
• /
• 2002

Recently, the existing embedded real-time operating systems(RTOSs) are being developed in terms of various modified versions in every application fields. Major characteristics and difference of these OSs lie in their distinct development of mechanisms which can be used in various environment and task-scheduling function which can control time-limited contingencies. In this paper, we design and implement round/robin scheduling algorithm based on time-sharing with equal-priority for multiple tasks which are provided preemptive and priority task allocation function in $\mu{C/OS-II}$ version 2.03. We propose the most important event-ready list structure in $\mu{C/OS-II}$; kernel, and provide the running result for multiple tasks with equal priority for the proposed structure.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.65 no.4
• /
• pp.255-261
• /
• 2016

Korean Power System are operating a load shedding system to prevent voltage instability phenomenon caused by severe line contingencies. In order to apply the load shedding scheme should be selected a location, amount, delay time. Current load shedding system is load shedding amount that has been calculated in the steady-state analysis to load shed the total amount in first level, load shedding amount calculated in advance, it is possible to perform an unnecessary load shedding. In this paper, set a multi-level load shedding control strategy step-by-step selection of load shedding amount for the prevention of excessive load shedding. In addition, through a voltage resilience analysis of the power system by applying motor load ratio and sensitivity parameter to selection the multi level load shedding ratio and delay time. For this reason, to take advantage of the limit data of interchange power, by utilizing interface power flow data to set a multi-level load shedding control strategy for the stabilization of the Korean Power System.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.5
• /
• pp.1689-1696
• /
• 2017

In recent academic and industrial circles of the Republic of Korea, the securement of available reactive power reserve against the line faults is at issue. Thus, simulations have been performed for the securing of effective reactive power reserve (effective Q) to prepare for the line faults and improve reactive power monitoring and control methods. That is, a research has been conducted for the fast-decoupled Newton-Raphson method. In this study, a method that distinguishes source and sink regions to carry out faster provision of information in the event of line fault has been proposed. This method can perform quantification with the formula that calculates voltage variations in the line flow. The line flow and voltage changes can be easily induced by the power flow calculation performed every second in the operation system. It is expected that the proposed method will be able to contribute to securement of power system stability by securing efficient reactive power. Also, the proposed method will be able to contribute to prepare against contingencies effectively. It is not easy to prepare quickly for the situation where voltage drops rapidly due to the exhaustion of reactive power source by observing voltage information only. This paper's simulation was performed on the large scale Korean power system in steady state.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.3
• /
• pp.393-401
• /
• 2020

According to the research and investigations performed on Port Facilities for cargo-works of hazardous materials around the Port of Busan, a conclusion was drawn that the manually operating foam tower monitors are ineffective as they are hard to access due to the radiant heat under contingency circumstances such as a fire. Moreover, in some cases, the effective range of Foam Tower Monitors are insufficient to reach docked ships and manifolds where hazardous materials are being unloaded. In addition, Dangerous Goods freights are inadequately and inefficiently stored regardless properties of hazardous substances due to complicated local regulations, and some are equipped with inapplicable facilities for docked ships. Therefore, in order to effectively counteract the contingencies and obtain safety, it would be recommended to install adequate facilities.

• Journal of Korean Library and Information Science Society
• /
• v.33 no.4
• /
• pp.1-18
• /
• 2002

Library and information science(LIS) has been focused on the issues of information poverty and barriers and their relations, mainly in terms of current information users. However, potential users usually out of sight in library and information services undoubtedly are to be developed as legitimate clientele. In this regard, this paper attempts to shed light on some factors related to the methodological underpinnings of LIS. Ethnographic research is particularly highlighted. Since the mid 1980s, as full-fledged research of analyzing the contingencies of information use as situated in particular times and places. md using that analysis to inform user-centered information systems design LIS researchers and practitioners have been exploring possible use of ethnographic approaches, especially in studies investigating information world of the socially marginalized. This Paper addresses issues in conducting ethnographic studies in the discipline. This paper also discusses the experiences in conducting ethnographic based research md how the results of their studies may be or have been useful in improving information services fir specific populations.