• Title/Summary/Keyword: Protective material

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Performance Improvement of Protective Relaying for Large Transformer by Using Voltage-Current Trend and Flux-Differential Current Slope Characteristic (전압-전류 추이와 자속-차전류 기울기 특성을 이용한 변압기 보호계전기법의 성능 개선)

  • Park, Chul-Won;Park, Jae-Sae;Jung, Yun-Man;Ha, Kyung-Jae;Shin, Myong-Chul
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.53 no.2
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    • pp.43-50
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    • 2004
  • Percentage differential characteristic relaying(PDR) has been recognized as the principal basis for power transformer protection. Second harmonic restraint PDR has been widely used for magnetizing inrush in practice. Nowadays, relaying signals can contain 2nd harmonic component to a large extent even in a normal state, and 2nd harmonic ratio indicates a tendency of relative reduction because of the advancement of material. Further, as the power system voltage becomes higher and more underground cables are used, larger 2nd harmonic component in the differential current under internal fault is observed. And then, conventional 2nd harmonic restraint PDR exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for performance improvement of conventional protective relaying. This paper proposes an advanced protective relaying algorithm by using voltage-current trend and flux-differential current slope characteristic. To evaluate the performance of the 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 WatATP, 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.

A study on fashion mask design trends for individual safety protection from harmful environments (유해환경으로부터 개인의 안전보호를 위한 패션 마스크 디자인 경향)

  • Dal A Lee;Chan Ho Kim
    • Journal of the Korea Fashion and Costume Design Association
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    • v.24 no.4
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    • pp.101-116
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    • 2022
  • The purpose of this study is to understand the trends of fashion mask designs as a fashion item with characteristics to protect individual health and safety from harmful environments. To this end, the concept, the trend analysis of the domestic and foreign mask markets, the type, characteristics of functional masks, and the design trend of fashion masks were analyzed. Research methods included case studies and literaturte on mask design, fashion magazines, fashion brand websites, fashion collections, and promotional material. First, masks for personal safety were classified as protective function masks from the natural environment, functional masks by industrial groups, masks for protective functions from biohazards, and masks for protective functions from various external activities. Through this analysis, the design trends of fashion masks were analyzed. The functional orientation of structure and functionality, the environmental orientation of sustainable eco-friendly methods, the fashion orientation of individual fashion styling, and the social functional orientation tend to transmit social messages. In the harmful environment of everyday life, items such as fashion masks with functionality and fashion characteristics should be continuously studied to integrate functional and design characteristics that can contribute to the future fashion industry and the fashion market as a sense of unity and responsibility.

Thermal Insulation of Protective Clothing Materials in Extreme Cold Conditions

  • Mohamed Zemzem;Stephane Halle;Ludwig Vinches
    • Safety and Health at Work
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    • v.14 no.1
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    • pp.107-117
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    • 2023
  • Background: Thermophysiological comfort in a cold environment is mainly ensured by clothing. However, the thermal performance and protective abilities of textile fabrics may be sensitive to extreme environmental conditions. This article evaluated the thermal insulation properties of three technical textile assemblies and determined the influence of environmental parameters (temperature, humidity, and wind speed) on their insulation capacity. Methods: Thermal insulation capacity and air permeability of the assemblies were determined experimentally. A sweating-guarded hotplate apparatus, commonly called the "skin model," based on International Organization for Standardization (ISO) 11092 standard and simulating the heat transfer from the body surface to the environment through clothing material, was adopted for the thermal resistance measurements. Results: It was found that the assemblies lost about 85% of their thermal insulation with increasing wind speed from 0 to 16 km/h. Under certain conditions, values approaching 1 clo have been measured. On the other hand, the results showed that temperature variation in the range (-40℃, 30℃), as well as humidity ratio changes (5 g/kg, 20 g/kg), had a limited influence on the thermal insulation of the studied assemblies. Conclusion: The present study showed that the most important variable impacting the thermal performance and protective abilities of textile fabrics is the wind speed, a parameter not taken into account by ISO 11092.

Preparation and characterization of Melamine-Formaldehyde Resin Microcapsules Containing Fragrant Oil

  • Hwang, Jun-Seok;Kim, Jin-Nam;Wee, Young-Jung;Yun, Jong-Sun;Jang, Hong-Gi;Kim, Sun-Ho;Ryu, Hwa-Won
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.11 no.4
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    • pp.332-336
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    • 2006
  • In this study, melamine-formaldehyde microcapsules were prepared via in situ polymerization using peppermint oil as a core material, melamine-formaldehyde as the wall material, Tween 20 as the emulsifier, and poly (vinyl alcohol) as a protective colloid. The melamine-formaldehyde microcapsules prepared in this study were then evaluated with regard to their structures, thermal properties, particle size distributions, morphologies, and release behaviors.

Measurements of Temperature Rise and Temperature Distribution of Samples by Infrared Radiation (적외선 복사에 의한 시료의 온도상승과 온도분포 측정)

  • Han, Jong-Sung;Kim, Ki-Hoon;Kim, Hoon
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2003.11a
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    • pp.133-137
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    • 2003
  • When a light is projected upon a material, part of its radiation energy is absorbed and the rest is reflected or transmitted according to the nature of the material. The molecules of the substance absorbing a light obtains the radiation energy to the wavelength of the light to make photochemical degradation by ultraviolet ray or thermal reactions like physical damage by infrared ray. The degree of damage by radiation energy varies to the substances of materials, the spectral power distribution of the light source and the duration of irradiation. Because the damage brings about a devaluation of material and once damaged, it is irretrievable, it is necessary to minimize the damage and conserve the native quality of a material by a protective lighting system. A measuring system was set up to measure the temperature rise of each sample by infrared radiation from light sources. And the temperature rise and temperature distribution by various infrared lamps were measured with varying time.

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Detoxification Properties of Surface Aminated Cotton Fabric (아민화 표면 처리된 면직물의 제독 성능 연구)

  • Kim, Changkyu;Kwon, Woong;Jeong, Euigyung
    • Textile Coloration and Finishing
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    • v.32 no.2
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    • pp.73-79
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    • 2020
  • Pursuing the fabric materials for military chemical warfare protective clothing with the improved detoxification properties, this study investigated the simple and effective cotton treatment method using pad-dry-cure process and 3-aminopropyltrimethox ysilane(APTMS) solution for surface amination. Detoxification properties of the untreated and treated cotton fabrics were evaluated via decontamination of chemical warfare agent simulant, DFP(diisopropylfluorophosphate). The surface aminated cotton fabric increased the rate of the hydrolysis of DFP by the factor of 3 and the decontamination ratio reached 88.2% after 24h. Therefore, the surface amination of the cotton fabric with APTMS can be an effective pathway to prepare the material for protective clothing against chemical warfare agents.

Research on the Favorite Design of Motocycle Suits (모터사이클 슈트의 디자인 선호도 조사)

  • 황승희;김여숙
    • Journal of the Korea Fashion and Costume Design Association
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    • v.5 no.1
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    • pp.73-83
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    • 2003
  • Out of a total of 437 subjects surveyed, 83.3 put on motocycle suits when they drive. Though the suits are not comfortable, many motocycle riders put them on for safty reasons. To protect a driver's body, motocycle suits should be patched with protective bands or safty pads in various areas like part of waist, backbone, pelvis and knees. The ratio of dissatisfaction with the preceding motocycle suits was great owing to inconvenience in washing and in posture, especially heavy suits. Their favorite suits were found to be linking or coupled types among two piece styles. Leather was shown to be the preferable material and they wanted designs which the protective bands, or pads can be attatched on each portion for needs of safty against impact but designed for comfort and ease of movenment.

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Effect of Polyopes lancifolia Extract on Oxidative Stress in Human Umbilical Vein Endothelial Cells Induced by High Glucose

  • Min, Seong Won;Han, Ji Sook
    • Preventive Nutrition and Food Science
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    • v.18 no.1
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    • pp.38-44
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    • 2013
  • The protective effect of Polyopes lancifolia extract on high glucose-induced oxidative stress was investigated using human umbilical vein endothelial cells (HUVECs). High concentration of glucose (30 mM) treatment induced HUVECs cell death, but Polyopes lancifolia extract, at concentrations of 25, 50, and 100μg/mL, protected cells from high glucose-induced damage. Furthermore, thiobarbituric acid reactive substances, intracellular reactive oxygen species, and nitric oxide levels increased by high glucose treatment were effectively decreased by treatment with Polyopes lancifolia extract in a dose-dependent manner. Also, Polyopes lancifolia extract treatment reduced the overexpressions of inducible nitric oxide synthase, cyclooxygenase-2, and nuclear factor-kappa B proteins activation that was induced by high glucose in HUVECs. These results indicate that Polyopes lancifolia extract is a potential therapeutic material that will reduce the damage caused by high glucose-induced-oxidative stress associated with diabetes.

Propolis Inhibits UVA-Induced Apoptosis of Human Keratinocyte HaCaT Cells by Scavenging ROS

  • Kim, Han Bit;Yoo, Byung Sun
    • Toxicological Research
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    • v.32 no.4
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    • pp.345-351
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    • 2016
  • Propolis is a resinous material collected by honeybees from several plant sources. This research aimed at showing its protective effect against UVA-induced apoptosis of human keratinocyte HaCaT cells. Using Hoechst staining, it was demonstrated that propolis (5 and 10μg/mL) significantly inhibited the apoptosis of HaCaT cells induced by UVA-irradiation. Propolis also showed the protective effect against loss of mitochondrial membrane potential induced by UVA-irradiaiton in HaCaT cells. Propolis also inhibited the expression of activated caspase-3 induced by UVA-irradiation. To investigate the role of ROS in UVA-induced apoptosis and protection by propolis, the generation of ROS was determined in cells. The results showed that the generation of ROS was markedly reduced in cells pretreated with propolis. Consequently, propolis protected human keratinocyte HaCaT cells against UVA-induced apoptosis, which might be related to the reduction of ROS generation by UVA-irradiation.

A New Technology of Hardening Porous Materials of Titan Powders

  • Belyavin, K.E.;Minko, D.V.;Reshetnikov, N.V.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1012-1013
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    • 2006
  • A technology of hardening porous materials of titan powders has been elaborated. The technology is based on passing alternating current with duration of 101101 s through porous (3540) blanks made by method of Sintering by Electric Discharge (SED) by passing a pulse of current with duration of 105103 s. The influence of technological regimes of porous blanks treatment on their structure and properties is investigated. Geometry and dimension of contact necks between powder particles of obtained samples are evaluated. Variations of porosity and strengths as well as microstructure of porous samples materials before and after treatment are investigated. Optimum range of treatment technological regimes is determined within which porosity of 3035 with maximum strength values.

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