• Herbal Formula Science
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• v.10 no.2
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• pp.127-141
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• 2002

Objectives: Haeganjeon(HGJ) has been used for the treatment of liver disease in traditional medicine. The present study was carried out to evaluate the antioxidant and protective effects of HGJ extract on oxidative damage of hepatocytes by tert-butyl hydroperoxide(t-BHP). Methods: In the linoleic acid water-alcohol system, the levels of lipid peroxide(LPO) were determined by TBA method. The scavenging effect of HGJ on ${\alpha},{\alpha}-diphenyl-{\beta}-picrylhydrazyl$(DPPH) radical was determined according to the method of Hatano. In the Fenton system(ferrous ion reaction with hydrogen peroxide), the levels of hydroxyl radical induced LPO in rat liver homogenate were determined according to the method of TBA. Inhibitory effect of HGJ on superoxide generation was measured by xanthine-xanthine oxidase system. In order to evaluate antioxidative activity of HGJ in the liver cell, cultured normal rat liver cells(Ac2F) were prepared and incubated with or without HGJ. After 18hr, cells placed in DMEM medium without serum, and then incubated with 1mM tert-butyl hydroperoxide(t-BHP) for 2hrs. Viable cells were detected by MTT assay. Conclusions: In the linoleic acid autoxidation system, HGJ extract significantly inhibited the time course of the lipid peroxidation. These effects were similar to those of BHA HGJ extracts showed about 70% scavenging effect on DPPH radical. And HGJ extract inhibited the lipid peroxide formation in rat liver homogenate induced by hydroxyl radical derived from Fenton system. In addition, HGJ extract protected the cell death induced by t-BHP and significantly increased cell viability in the normal rat liver cell. These result indicated that HGJ extract might playa protective role against oxidative hepatic cell injury by means of free radical scavenger.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.155-157
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• 2005

Digital relays have numerous advantages over traditional analog relays, such as the ability to accomplish what is difficult or impossible using analog relays. This paper presents the protective relay modeling of generator using Real Time Digital Simulator(RTDS). The developed model is applied to the test system and the simulation results are evident that they performs satisfactory.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.640-642
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• 1995

This paper describes the present state and development prospect on the protective relaying under high resistance earth faults in transmission systems. Especially it is difficult to detect the fault accompanied with high resistance contary to low resistance. In the complicated power system if the detection is failed, power failure will be occured in large area. New technology with respect to such a problem must be developed. This paper introduces research and development trend in home and abroad.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.48-50
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• 1993

One of the most important functions in the distribution automation is the service restoration. This paper proposes the new method which considers not only constraints of voltage, line current and bank capacity but also the operating characteristics of protective devices such as OCR and reclosers.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.233-236
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• 1989

This paper deals with the expert system using network configuration and input information composed of protective relays and tripped circuit breakers. This system has knowlegebase independent on network dimension because network representation consists of the type of the matrix. Therefore, the knowlege of network representation is simplified, the space of knowlege is reduced, the addition of facts to the knowlege is easy and the expansion of facts is possible. In this paper, the network representation is defined to system matrix. This expert system based on the system matrix diagnoses normal, abnormal operations of protective devices as well as possible fault sections. The brach and bound search technique is used: breadth first technique mixed with depth first technique of primitive PROLOG search technique. This system will be used for real time operations. This expert system obtaines the solution using the pattern matching in working memory without no listing approach for rule control. This paper is written in PROLOG, the A.I. language.

• Fire Science and Engineering
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• v.32 no.1
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• pp.81-88
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• 2018

Air and ultra lightweight aerogels were used to lighten the weight of the firefighters' protective clothing. In order to lighten the firefighters' protective clothing composed of 3 layers (outer shell, mid-layer, lining), it was most effective to replace the lining which occupied the largest weight in the total weight with the new materials. Thermal protective performance tests were carried out on flame (ASTM D 4108), radiant heat (KS K ISO 6942) and mixing heat (KS K ISO 17492) of flame and radiation. When the lining felt was replaced with an air layer, the air layer must be at least 3 mm to meet the KFI and ISO standards for the thermal protective performance. However, even if the thickness of the air layer increased to 10 mm, the thermal protective performance was lower than that of the existing products. When the felt was replaced with aerogels, the TPP rating (ASTM D 4108) satisfied the KFI standard at the 2 mm thickness of the aerogels. When the thickness of the aerogels was 3 mm, the TPP rating was improved about 140% compared to the existing products. It was confirmed that not only weight reduction but also thermal protective performance was improved by use of aerogels. However, due to the fragile nature of aerogels, a method of fixing them to a constant thickness between layers constituting a firefighters' protective clothing should be considered in the future.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.370-371
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• 2011

This paper proposed an under-voltage relay algorithm module for a network based protective relay simulator. The simulation system is based on the client-server paradigm. The relaying simulator which consists of server-side relay models and user interface provides network-based simulation environment for a variety of protective relaying algorithms. The performance of the relay algorithm was verified by comparing the results of under-voltage relay algorithm in the simulator with the results of the C language implementation.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.167-173
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• 2011

This paper presents a method for the development of the impedance locus to test the dynamic characteristics of protective relays. Specifically, using the proposed method, the impedance locus can comprise three impedance points, and the speed of impedance trajectory can be adjusted by frequency deviation. This paper is divided into two main sections. The first section deals with the configuration of impedance locus with voltage magnitude, total impedance magnitude, and impedance angle. The second section discusses the control of the locus speed with the means of the deviation between two frequencies. The proposed method is applied to two machine equivalent systems with offline simulation (i.e., PSCAD) and real-time simulation (i.e., real-time simulation environment) to demonstrate its effectiveness.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.382-388
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• 2004

The most widely used primary protection for the internal fault detection of power transformers is current percentage differential relaying(PDR). However, the harmonic components could be decreased by magnetizing inrush when there have been changes to the material of iron core or its design methodology. The higher the capacitance of high voltage status and underground distribution, the more differential current includes the second harmonic component during occurrence of an internal fault. Therefore, the conventional harmonic restraint methods need modification. This paper proposes an advanced protective relaying algorithm by fluxt-differential current slope characteristic and trend of voltage and differential current. To evaluate the performance of proposed algorithm, we have made comparative studies of PDR fuzzy relaying, and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP99, and data collection is made through simulation of various internal faults and inrush. As the results of test. the new proposed algorithm was proven to be faster and more reliable.

• Korean Journal of Pharmacognosy
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• v.25 no.1
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• pp.59-69
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• 1994

Polygonum aviculare L. was extracted by methanol and then fractionated systematically with solvents and column chromatographic method in order to isolate ingredients with anti-lipid peroxidation and liver protectective effects. Among these fractions, ethylacetate soluble part(MWE) showed the strongest in the anti-lipid peroxidation. Furthermore, the crude subtraction(MWE 4) with Rf value near 0.42, which is separated from MWE by column chromatography using a solvent system, inhibited the lipid peroxidation of rat liver in vitro. Moreover, MWE 4 decreased GOT, GPT and TBA value compared with control and suggested high protective effects against hepatotoxicity induced by carbon tetrachloride in mice. The active compounds in MWE 4 were assumed to be flavonoid glucosides.