• Title, Summary, Keyword: Electret

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Electret Characteristics of polyethylene terephthalate for electret installation (전기설비용 polyethylene terephthalate의 electret 특성연구)

  • 국상훈;서장수
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.10 no.3
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    • pp.78-85
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    • 1996
  • This paper experience the mechanism for the electret of polyethyleneterephthalate(PET) by using surface potentail measurement means. We investigated the internal charge production and becoming week by evaporating electrode in sample structure of electret coexist with hetero charge and homo charge, as the study based on two charge theory. We expects that the hetero charge consists of the dipole and ion displacement of internality, the homo charge consists of injected charge of externality.

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Collection Performance of an Electret Cabin Air Filter for Fine Particles (자동차용 정전 필터의 미세 입자 포집 특성)

  • Ji, Jun-Ho;Kang, Suk-Hoon;Kim, Dong-Choul;Hwang, Jung-Ho;Yoon, Woong-Sup;Bae, Gwi-Nam
    • Proceedings of the KSME Conference
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    • pp.85-90
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    • 2001
  • This work presents experimental results of filter media test by using particles from $0.02\;to\;0.6{\mu}m$ in diameter and by applying different charging states. In order to investigate the electret filter performance, the collection efficiency and the pressure drop of filter were measured. The face velocities of test filters varied from 2.4 to 20.4 cm/s. Another experiment setup for the cartridge cabin air filter was used to get an collection efficiency in submicron region. After charging level of electret filter severely decreased, the change of collection efficiency was verified. Experimental results show that the reliability of electret filters can be poor in some conditions.

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Development of Infra-sonic Transducer Manufactured by Corona Charging Electret (코로나 대전 일렉트렛트로 제작된 초저주파 변환기의 개발)

  • 송재열;정동회;김상걸;안준호;김성열;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.942-945
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    • 2000
  • Recently, electret applications have placed the focus on polymer thin film because electrical properties of a blend are studied. In this paper, we hale measured the infra sonic frequency by using Electret Sensor. Electret is formed by appling the voltage range of -4[kV] to -8[kV] to PTFE film and the sensor is manufactured by moment method to detect the infra-sonic signal. Electret Infrasonic Transducer, which is designed and manufactured by using of the moment method according to the potential and electric field simulation , shows its promising result, since the average rising rate of sensitivity is 7.68 [dB/oct] under 1[Hz], and the average values are within ${\pm}$ 1 [dB/oct]. As a result, it is believed that the characteristics of acquired transducer can be applied to the medical treatment, the industry, and the animal life researches, and also the study on noise elimination is required.

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Effect of Particle Loading on the Collection Performance of an Electret Cabin Air Filter for Submicron Particles (입자 퇴적이 승용차용 정전 필터의 미세 입자 포집 특성에 미치는 영향)

  • Ji, Jun-Ho;Gang, Seok-Hun;Hwang, Jeong-Ho;Bae, Gwi-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.8
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    • pp.1102-1114
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    • 2002
  • An electret filter is composed of permanently charged electret fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using poly-disperse particles when submicron particles were loaded. Long-term experiments were conducted by applying two different charging states, which were spray electrification and charge equilibrium by bipolar ionization. In order to investigate the effect of particle loading in filter media, NaCl particles were generated from 0.1% and 1% solutions by an atomizer. Liquid DOS particles were used to evaluate the effect of liquid particles on the collection efficiency of an electret filter. The results show significant effect of charge amount and size distribution of loading particles on the collection performance of a filter media in submicron region. Smaller particles loaded in electret fibers cause a more rapid degradation in collection efficiency and have lower minimum efficiency with time. The pressure drop of a filter media do rarely increase when the collection efficiency decreases to the minimum value. For the larger particles charged by spray electrification, which have charge amounts more than that of Boltzmann equilibrium charge distribution, the pressure drop of a filter media slowly increases in comparison with that of equilibrium charged particles. For DOS particles it is shown that the charging level of an electret filter severely decreases and the collection efficiency is below 10% in some particle size range.

고분자 일렉트렛트와 압전기

  • 이준웅
    • 전기의세계
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    • v.31 no.10
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    • pp.681-688
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    • 1982
  • Electret의 기초적인 System을 이해한다는 것은 새로운 응용면을 개척하는데 중요한 요소가 되는데 이런 점을 고려하여 여기서는 프라스틱 Electret의 현상과 고분자압전기에 대하여 그 개요를 소개한다.

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Energy Dependancy of the Polyethylene Terephthalate Film for Radiation Detector (방사선 검출기용 PET 박막의 에너지 의존성)

  • Back, Geum-Mun;Kim, Keon-Chung;Kim, Wang-Gon;Hong, Jin-Woong;Yi, Byong-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.71-74
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    • 2002
  • Currently small and accurate dosimeters are on the rise. In this study, the feasibility and energy dependency of the electret dosimeter that made of PET (polyethylene terephtalate) were observed by irradiating 4, 6, 15 MV photon beams from the clinical linear accelerator to develop a dosimeter for the clinical field. $10{\times}10cm$ field size of the photon beams were irradiated to the electret dosimeter where the 2.5 cm depth in the polystylene phantom from 100 cm SSD, while 300 DCV was applied to the electret dosimeter. The result showed that the absorbed dose was proportional to the charge linearly, and the volume of a dosimeter could be reduced and the signals were high enough. According to this study, it was found that the polymer electret detector could be produced as a large quantity with a small cost and showed the feasibility of a realtime measurement.

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Numerical analysis of particle behavior around a bipolar charged electret fiber (정전 섬유필터 주위의 입자포집 및 거동에 관한 수치해석적 연구)

  • An, Gang-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.11
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    • pp.1509-1517
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    • 1997
  • Charged and uncharged particle motions and collection characteristics around a bipolar charged rectangular shape electret fiber are studied numerically. Particle inertia, fluid drag, Coulomb force and polarization force are considered to predict the particle motion around the electret fiber. The effects of particle sizes, flow velocities, number of charges and polarities are also systematically investigated. For small size particles, the single fiber collection efficiency is greatly dependent on the charge polarity and the number of charges on a particle. However, particles larger than 5.mu.m do not show charging effect on collection efficiencies in the flow velocity ranges from 1.5 cm/s to 150 cm/s when the maximum charges are within +5 to -10. The results show that a strong electric field gradient at the corner of the bipolar charged fiber plays a very important role on collecting particles regardless of its charge polarity because of the polarization force. It also shows that the most penetrating particle size for a single electret fiber decreases as the flow velocity increases and the number of charges of a particle decreases.

Characteristic Analysis of Electret Filters made by Electrospinning (전기방사를 통한 정전필터제조 및 특성분석)

  • Ahn, Young-Chull;Kim, Gil-Tae;Kim, Seong-Kon;Lee, Jae-Keun;Kim, Jong-Won
    • Proceedings of the SAREK Conference
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    • pp.1134-1138
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    • 2008
  • Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, electrical properties and filtration performance of electrospun filter media are quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. Electrospun filters show same collection efficiency with low pressure drop compare to commercialized HEPA filters. Surface charge potential and surface charge density of electrospun filters are increased with increasing applied voltage. Also collection efficiency of electrospun filters is increased with increasing surface charge potential and surface charge density.

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A study on Improvement of Electric charge storage characteristics using $Teflon^{(R)}FEP$ film ($Teflon^{(R)}FEP$ film을 사용한 전하보존특성 향상에 관한 연구)

  • Kim, Seong-Jun;Lee, Hyeon-Seok;Kwon, Jeong-Yeol;Kim, Ji-Kyun;Lee, Heon-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.539-540
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    • 2006
  • In this paper, We examine that characteristics of formative electret with polymer film and electric charge storage using grid corona discharge. compound polymer of fluorine resin used for material in electret because of high electric charge accumulation, excellent electrical and physical characteristic. All experiments were carried out with circular samples of $Teflon^(R)FEP$ film, 12.5[${\mu}m$] thick. As experiment variables, we used voltage, electrode thickness, discharge electrode gap, and discharge time. According to this variables, we studied on characteristics of formative electret and electric charge storage. Additionally we make a comparative study of the result between the grid corona discharge and needle electrode discharge.

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