• Title/Summary/Keyword: protective systems

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Protective Effect of Lonicerae Flos Aqueous Extracts on a Pressure Overload-induced Heart Failure Model

  • Shin, Jae-wook;Jang, Woo-seok;Baek, Kyung-min
    • The Journal of Internal Korean Medicine
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    • v.38 no.6
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    • pp.877-890
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    • 2017
  • Objectives: Lonicerae flos (LF), a dried flower part of Lonicera japonica Thunb., has been widely used in Korean medicine as anti-inflammatory and antioxidative agent. The purpose of this study was to determine the cardioprotective effects of LF, through potential antioxidant effects, on the pressure overload (PO)-induced heart failure (HF) in C57BL/6 mice after transverse aortic constriction (TAC) surgery. Methods: Resveratrol (10 mg/kg body weight) or LF (125, 250 or 500 mg/kg body weight) was orally administered, once daily for 14 days, starting 14 days after TAC surgery. Changes in the mortality, body weights, heart weights, histopathology of the heart, and antioxidant defense systems of the heart were analyzed. Results: Marked and noticeable increases of heart weights, mortalities, and hypertrophic, focal, and lytic fibrotic histological changes in the LVs were observed, with destruction of heart antioxidant defense systems after surgery. However, HF signs, induced by TAC surgery through PO, and destruction of heart antioxidant defense systems were significantly and dose-dependently inhibited by 14 days of maintained oral treatment with LF 500, 250 or 125 mg/kg. Treatment with 250 mg/kg LF was comparable to treatment with 10 mg/kg resveratrol. Conclusions: The results in this study suggest that oral administration of LF favorably relieves PO-induced HF following TAC, through increase of heart antioxidant defense systems. The overall effects of 250 mg/kg LF were similar to those of 10 mg/kg resveratrol. More detailed mechanistic studies should be conducted in the future, with screening of the biologically active compounds in LF.

Protective Effects of a Ginseng Component, M altol(2- M ethyl-3- Hydroxy-4- Pyrone) against Tissue Damages Induced By Oxygen Radicals

  • Jae-Gook Shin;Jon
    • Proceedings of the Ginseng society Conference
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    • 1990.06a
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    • pp.45-48
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    • 1990
  • Maltol(2-methyl-3-hydroxy-r-pyrone), a component known to be present in Korean Ginseng root showed an antioxidant action but its potency as an antioxidant was low; about 1150th that of other antioxidants such as p-phenylenediamine , BHA and BHT. However, maltol was able to protect the oxidation adamants in biological systems such as adriamycin-induced membrane damage in isolated cardiomyocytes, parquet-induced toxicities in isolated hepatocytes and repercussion injury in isolated hearts. The antioxidant action of maltol was also shown to be effective in vivo. The antioxidant action of this compound was probably due to the removal of hydroxyl radicals. In view of the roles of oxygen radical in various pathological processes, Korean Ginseng root, which contains several antioxidants including maltol, is expected to have beneficial efforts on the oxygen radical-involved processes. Keywords Maltol, Oxygen free radicals, Lipid preoccupation, Repercussion injury and Korean ginseng

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A Response Characteristics Analysis of Synchronous Machine Generator According to an Exciter Models (여자기 모델에 따른 동기 발전기 단자전압 응답 특성분석)

  • Im, Ik-Heon;Ryu, Hong-U;Kim, Chan-Gi;Kim, Gyeong-Cheol;Kim, Jeong-Hun
    • Proceedings of the KIEE Conference
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    • 1996.07a
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    • pp.368-371
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    • 1996
  • The basic function of an excitation system is to provide direct current to the synchronous machine field winding. In addition, the excitation system performs control and protective functions essential to a satisfactory performance of a power system by controlling the field voltage and thereby the field current. This paper describes the characteristics and modeling of different types of excitation systems and discusses dynamic performances. In this paper, we modified IEEE ACIA and STIA excitation system to simple system. The automatic voltage control system which had been developed by KEPRI is used for experiments and simulations.

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Child Abuse (아동학대)

  • Kim, Choon-Kyung;Lee, Ju-Ok;Song, Young-Joo
    • Korean Journal of Child Studies
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    • v.30 no.6
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    • pp.349-360
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    • 2009
  • During the last ten years, a number of the substantiated child abuse cases, studies, and newspaper articles in relation to child abuse have increased rapidly. Newspaper reports on physical abuse cases decreased, while articles on those of the sexual abuse and negligence increased after the year of 2000. However, the reason of child abuse was less studied, in comparison to the substantial number of research on the policy and the negative effects of child abuse. It is suggested that child abuse studies and policies should be performed from a pre-preventive perspective as well as a pro-protective perspective. The research regarding child abuse has to be conducted in the ecological perspective which includes not only the problems of children and their families, but also sociocultural issues. The results of studies on child abuse should be applied for the actual policy and systems improvement.

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Protective Effects of a Ginseng Component, Malto1(2-Mlethyl-3-Hydrox)-4-Pyrone) against Tissue Damages Induced By Oxygen Radicals (활성산소에 의한 조직손상에 미치는 인삼성분의 보호효과)

  • Jae-Gook Shin;Jon
    • Journal of Ginseng Research
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    • v.14 no.2
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    • pp.187-190
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    • 1990
  • Maltol(2-methyl-3-hydroxy-r-pyrone), a component known to be present in Korean Ginseng root showed an antioxidant action but its potency as an antioxidant was low: about 1150th that of other antioxidants such as pphenylenediamine, BHA and BHT. However, maltol was able to protect the oxidation damages in biological systems such as adriamycin-induced membrane damage in isolated cardiomyocytes, paraquat-induced toxicities in isolated hepatocytes and reperfusion injury in isolated hearts. The antioxidant action of maltol was also shown to be effective in vivo. The antioxidant action of this compound was probably due to the removal of hydroxyl radicals. In view of the roles of oxygen radical in various pathological proceises, Korean Ginseng root which contains several antioxidants including maltol is expected to have beneficial effects on the oxygen radical-involved processes.

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A Special Protection Scheme Against a Local Low-Voltage Problem and Zone 3 Protection in the KEPCO System

  • Yun, Ki-Seob;Lee, Byong-Jun;Song, Hwa-Chang
    • Journal of Electrical Engineering and Technology
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    • v.2 no.3
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    • pp.294-299
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    • 2007
  • This paper presents a special protection scheme, which was established in the KEPCO (Korea Electric Power Corporation) system, against a critically low voltage profile in a part of the system after a double-circuit tower outage. Without establishing the scheme, the outage triggers the operation of a zone 3 relay and trips the component. This sequence of events possibly leads to a blackout of the local system. The scheme consists of an inter-substation communication network using PITR (Protective Integrated Transmitter and Receiver) for acquisition of the substations' data, and under-voltage load shedding devices. This paper describes the procedure for determining the load shedding in the scheme and the experiences of the implementation.

A Study of the Reliability of Distribution System for Malfunction of Protective Relay (보호계전기의 오동작에 의한 배전계통 신뢰도에 대한 연구)

  • Shin, Jung-Jin;Lee, Hee-Tae;Kim, Jae-Chul
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.205_206
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    • 2009
  • Protection system is important part in distribution system. Protection system in power systems can fail either by not responding when they should(failure to operate) or by operating when they should not(false tripping). Customers has dissatisfied that due to the failure of protection system. The reliability of distribution system also has influenced. However, the failure of protection system can reduced by the maintenance. This paper has focused on malfunction of protection system. The approach is based on Markov models.

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Characterization of Mouse Peroxiredoxin III Genomic DNA and Its Expression

  • Lee, Tae-Hoon;Kim, Sun-Uk;Lee, Kyung-Kwang;Yu, Dae-Yeul
    • Proceedings of the KSAR Conference
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    • 2002.06a
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    • pp.64-64
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    • 2002
  • Peroxiredoxins (Prxs) possess protective activity against oxygen radicals generated by thiol-catalyzed oxidative systems. We already reported the genomic structure and its expression of mouse Prx Ⅰ, Ⅱ, and 1-Cys Prx. However, the Prx Ⅲ has not been determined. That was initially defined transiently expressed gene, mouse MER5, of murine erythroleukaemia cell differentiation. In addition, this protein was recently redefined a member of the thiol-specific antioxidant gene family. (omitted)

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A Section Load Management Method using Daily Load Curve in Distribution Systems (일부하 곡선을 이용한 배전계통 구간부하 관리방법)

  • Lim, Seong-Il
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.6
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    • pp.47-52
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    • 2012
  • DAS(Distribution Automation System) is equipped with several software applications such as service restoration, loss minimization, and protective relay coordination. The software applications of DAS are very sensitive to the amount of section load being carried by a particular section of distribution lines. Moreover, each software application requires a different parameter of the section load according to its purpose. Therefore, This paper proposes a new section load management method using real-time measurement data of the distribution lines. In order to provide accurate data to DAS applications, this method considers section loads in terms of the relationship of power versus time. In order to establish that the proposed method is feasible, a performance-testing simulator was developed, and case studies were conducted for a modified real distribution network.

A Study on the Harmonics Effect of Disc-Type Over Current Ground Relay for Emergency Generator Protection (비상발전기 보호용 원판형 지락과전류계전기의 고조파영향에 관한 연구)

  • Kim, Kyung-Chul;Kho, Hun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.6
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    • pp.58-62
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    • 2015
  • When an emergency generator is running, it supplies the power for critical loads. Generator protection requires the consideration of many abnormal conditions that may occur with generators include overvoltages and ground faults. Modern day power systems create harmonics within the electrical network that can have an impact upon the associated protective system. This paper focuses on the analysing of the cause and development of a solution for the malfunction of induction disc type overcurrent ground relay by generation of harmonics during emergency generator operation.