• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.323-324
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• 2015

Voltage sag phenomenon is known as one of the important problems that brought huge economic losses in the modern industry. The voltage sag assessment is to predict an annual expected sag frequency (ESF) at concerned consumers caused by fault in the system. An area of severity (AOS) assessment is defined as a set of the fault positions that can result in the voltage sag bigger than certain level for multi-concerned buses simultaneously. This paper introduces how to determine a method for evaluating the voltage sag performance based on the AOS assessment.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.37-40
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• 2008

This paper presents the results of a simulation to analyze the effects of voltage sag on high-pressure discharge lamp(400[W]). In this paper, voltage sag is considered a reduction between 0 and 0.9[p.u] in nominal voltage magnitude, with duration between 0.01 and 90cycle. The simulation results depict the characteristics of the lamp about operating limits during voltage sag by the magnitude and duration of sag in CBEMA curve.

• Journal of Power Electronics
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• v.2 no.3
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• pp.162-170
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• 2002

Voltage sag detection algorithm for voltage sag corrector is proposed in this paper. To quantify the standard of voltage unbalance under the faulted conditions, the 3-phase unbalanced voltages are decomposed into two balanced 3-phase symmetrical components of the positive and negative sequence voltages, which is defined by the magnitude factor (MF) and unbalance factor (UF). It is analyzed that MWF and UF values are given as the dc constant values even though under the voltage unbalance condition. This paper also proposes the control scheme of the instantaneous voltage sag corrector based on this detection algorithm. The validity of the proposed algorithm is verified through the EMTDC simulation and experiments.

• Journal of the Korea Convergence Society
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• v.4 no.1
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• pp.33-41
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• 2013

This paper presents an adaptive recursive least squares algorithm (ARLS) for detecting voltage sag and voltage swell events in power systems. Different methods have been developed to detect voltage sag and voltage swell. Some of them use window techniques, which are too slow when voltage sag or swell mitigation is required. Others depend on the extraction of a single non-stationary sinusoidal signal out of a given multi-components input signal, and therefore they don't consider the harmonic components in calculating the voltage root mean square value (rms). The method, proposed in this paper, is capable of estimating the voltage rms taking into account all harmonic components. The method is tested by applying it to different, simulated signals using ATP program, and compared with voltage sag detection algorithms.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.50-57
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• 2011

This paper proposes a boost type single-phase inverter system to compensate the voltage sag appeared on source side. The proposed system is composed of a boost converter, a PWM inverter, and a bypass diode. If the voltage sag has appeared in input voltage, the boost converter would be operated to compensate it in the proposed system. The boost converter would not be operated when the magnitude of input voltage is more than 0.9 pu. The output voltage is kept constant by a direct-quadrature frame controller in the inverter. A 300 W class boost type inverter system was simulated, and the validity of the proposed system was verified by carrying out experiments.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.11
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• pp.558-565
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• 2000

In this paper, we propose a method for mitigating for mitigating the effect of voltage of voltage sag in radial power distribution systems using load transfer switching (LTS). The term of LTS is defined that the weakness load points for voltage sag transfer to the alternative source during the fault clearing practices. The sequenced of proposed LTS method is divided into the search of weakness points for voltage sag using the risk assessment model and transfer behavior of weakness points. The search of weakness point is carried out using the risk assessment model of voltage sag and Monte Carlo simulation method and the historical reliability data in Korea Electric Power Corporation (KEPCO) are also used. Through the case studies, we verify the effectiveness of proposed LTS method and present the searching method of effective application points of LTS method using the risk assessment model.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.128-130
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• 2003

In recent years, both utilities and users have expressed their deep concerns about the quality of electric power. Expressed, voltage sag which is one of power quality disturbance is very serious power quality problem on the power system. Voltage sag is a decrease to between 0.1 and 0.9 pu in rms voltage magnitude on the power system for durations from 0.5 cycles to 1 minute. These voltage sags are usually caused by fault condition, overload, and starting of large motors. In this paper, different types of voltage sags are simulated by using EMTP. This paper describes the distinctive characteristic for various sag origins, proposes the effective technique for voltage sag detection using EMTP.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.191-200
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• 2002

When power consumption increases, power supply must be efficient and reliable for good power quality. The studies on compensation system of power quality are processing actively. Voltage sag among of factors for power quality is generally PI dual control that voltage sag compensation is used. But this control is no more available since of 120[KHz] ripple rejection. So we proposed the control algorithm using PID control in 3-phase unbalanced power system and the series voltage compensator, when voltage sag occurs.

• Archives of Pharmacal Research
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• v.28 no.7
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• pp.848-853
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• 2005

Synurus deltoides was previously found to possess significant anti-inflammatory activity especially against chronic inflammation, and strong analgesic activity in vivo. In this study, new anti-inflammatory formulation containing S. deltoides extract as a major ingredient was prepared and in vivo activity was evaluated. The plausible action mechanism was also investigated. The new formulation (SAG) contains 1 part of S. deltoides extract, 0.9 part of Angelica gigas extract and 0.9 part of glucosamine sulfate (w/w). SAG inhibited dose-dependently edematic response of arachidonic acid (AA)- and 12-O-tetradecanoyl 13-acetate (TPA)-induced ear edema in mice, which is an animal model of acute inflammation. SAG showed 44.1 % inhibition of AA-induced ear edema at an oral dose of 50 mg/kg. In an animal model of chronic inflammation, SAG clearly reduced the edematic response of 7 -day model of multiple treatment of TPA (38.1 % inhibition at 200 mg/kg/day). Furthermore, SAG (50-800 mg/kg/day) as well as S. deltoides extract (285 mg/kg/day) significantly inhibited prostaglandin $E_2$ production from the skin lesion of the animals of 7-day model. These results were well correlated with in vitro finding that SAG as well as S. deltoides extract reduced cyclooxygenase (COX)-1- and COX-2-induced prostanoid production, measured in mouse bone marrow-derived mast cells. Therefore, these results suggest that SAG possesses anti-inflammatory activity in vivo against acute as well as chronic inflammatory animal models at least in part by inhibition of prostaglandin production through COX-1/COX-2 inhibition. And COX inhibition of SAG is possibly contributed by S. deltoides extract among the ingredients. Although the anti-inflammatory potencies of SAG were less than those of currently used anti-inflammatory drugs, this formulation may have beneficial effect on inflammatory disorders as a neutraceutical.

• Parasites, Hosts and Diseases
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• v.49 no.3
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• pp.207-212
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• 2011

Rapid serodiagnostic methods for Toxoplasma gondii infection in cats are urgently needed for effective control of transmission routes toward human infections. In this work, 4 recombinant T. gondii antigens (SAG1, SAG2, GRA3, and GRA6) were produced and tested for the development of rapid diagnostic test (RDT). The proteins were expressed in Escherichia coli, affinity-purified, and applied onto the nitrocellulose membrane of the test strip. The recombinant SAG1 (rSAG1) showed the strongest antigenic activity and highest specificity among them. We also performed clinical evaluation of the rSAG1-loaded RDT in 182 cat sera (55 household and 127 stray cats). The kit showed 0.88 of kappa value comparing with a commercialized ELISA kit, which indicated a significant correlation between rSAG1-loaded RDT and the ELISA kit. The overall sensitivity and specificity of the RDT were 100% (23/23) and 99.4% (158/159), respectively. The rSAG1-loaded RDT is rapid, easy to use, and highly accurate. Thus, it would be a suitable diagnostic tool for rapid detection of antibodies in T. gondii-infected cats under field conditions.