• Title/Summary/Keyword: 자기차폐

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Design of Magnetic Field Compensation System Model for AC Magnetic Field Shielding (교류자기장 차폐를 위한 자기장 상쇄장치 모델의 설계)

  • Choi, Hak-Yun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.7
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    • pp.78-82
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    • 2011
  • In this paper, magnetic field compensation system with an open architecture and can be installed indoors is designed and measured by fabricated. To verify the shielding effectiveness, two rectangular helmholtz coils with 3-axis are fabricated to generate magnetic field and measured magnetic field inside compensation coil for 1~60[Hz], According to measurements, AC shielding effectiveness of compensation system is 96[%] of 1[Hz], 95[%] of 30[Hz] and 90[%] of 60[Hz]. The performance of system therefore can be used as the magnetically shielded room for medical and industrial field.

Development of a HTS SQUID gradiometer system for the measurement of very weak magnetic field in an unshielded environment (비자기차폐환경에서 미세 자기장 측정을 위한 고온초전도 gradiometer 시스템의 개발)

  • Kim, In-Seon;Kim, Jin-Mok;Park, Yong-Ki
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.151-154
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    • 2000
  • We have developed a YBCO SQUID gradiometer system for the measurement of a very weak magnetic field in an unshielded environment. The system consists of a SQUID gradiometer sensor, low noise pre-amp, and FLL(fluxlocked loop) control electronics. The gradiometer sensors have been fabricated on STO bicrystal substrates, and exhibit a magnetic noise of 300 fT/${\surd}$ Hz/cm at 100 Hz. The overall magnetic field noise of the SQUID gradiometer system was about 10 pT/${\surd}$ Hz/cm at 10 Hz without any magnetic shield. The system demonstrated a high stability for a long time, and real-time measurement resolution ${\le}$ 100 pT/cm in the unshielded environments.

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Electroless Ni plating on the polyimide film (폴리이미드 필름에의 무전해 니켈도금)

  • Kim, Yu-Sang;Yun, Hui-Tak
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.316-317
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    • 2015
  • 무전해 도금은 금속이온을 수용액 상태에서 석출시키는 방법으로서 전기를 사용하지 않고 환원제의 자기촉매 방법에 의해 금속을 도금하는 방법이다. 두께를 확보하기 위한 화학적 무전해 도금에서는 환원제를 사용하지만 선택적 도금에서는 환원제를 사용하지 않는 치환도금법이 주로 사용되고 있다. 최근 전자파 차폐, 포장기술의 응용이 확대되면서 정보 통신 스마트폰, 전자기술과 자동차 산업에 많은 고분자 복합도금이 널리 확대되고 있다. 최근 해외에서도 고분자와 비금속재료의 복합도금 기술이 관심을 끌고 있다. 2013년 중국의 J. B. Fei 등은 Ag나노체인 합성물에 필요한 비대칭형의 공유결합으로써 나선형의 자기배열 $AgNO_3$와 멜라민 특성을 보고하였다. 무전해 니켈 복합도금은 내마모성, 내식성과 비금속재료의 선택적인 첨가로 다양한 고분자 첨가물을 적용할 수 있다. 유전상수가 낮고 열적 안정성이 우수하여 노트북 컴퓨터나 스마트폰 표면에 니켈-폴리이미드 복합도금도 개발되고 있다.

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Magnetic Wireless Power Transfer Antenna Using Ferrite (페라이트를 이용한 자기장 무선전력전송 안테나)

  • Ko, Nak-Young;Lee, Bon-Young;Song, Seong-Kyu;Park, Woo-Jin;Seo, Seok-Tae;Bien, Franklin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.7
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    • pp.49-54
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    • 2017
  • In this paper, we propose magnetic field wireless power transfer antenna using Ferrite. It is possible to transfer magnetic field wireless power without independent ground by using characteristic of ferrite in the point that conventional magnetic field wireless power transfer was possible with independent grounding. Ferrite has a shielding effect of magnetic field and reduces leakage power, thereby improving transfer efficiency. We propose an antenna for magnetic field wireless power transfer using ferrite and confirmed that it is transmitted by 5W magnetic field wireless power through experiments. The wireless power transfer proposed in this paper can be applied variously to the Internet of things by using the magnetic field wireless power transfer through the metal.

Comparison of SE Evaluation Methods for HEMP Shelters (HEMP 방호시설의 SE 평가방법의 비교)

  • Chung, Yeon-Choon;Lee, Jongkyung;Kwun, Suk-Tai
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.11
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    • pp.1197-1200
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    • 2014
  • Two test standards to be applied for evaluating shielding effectiveness of HEMP protection facilities, MIL-STD-188-125-1 and IEEE std. 299, provide different test results in spite of the same facility. In particular, at the frequency range of 10 kHz~20 MHz, it is confirmed that the test results by the IEEE Std. 299 are about 20~30 dB lower than the evaluated results by MIL-STD-188-125-1. These results are due to the different measurement conditions specified in the two test standards. Therefore, IEEE Std. 299 can be applied for the shortening of test distance, but the required SE performance based on MIL-STD-188-125-1 must be modified.

Satellite Anomalies due to Spce Environment Events (우주환경 이벤트에 의한 위성의 이상현상)

  • Park, Jae-Woo;Jeong, Cheol-Oh
    • Journal of Satellite, Information and Communications
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    • v.6 no.2
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    • pp.102-106
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    • 2011
  • Space Environment including Solar activities such as Solar explosion, Corona Mass Ejection(CMS) is always not friendly for human. Especially it may be fatal to artificial satellites. The lifetime of geostationary communication satellites are reducing due to plasma such as electrons, protons etc. emitting from Sun. This is because the active components constituting communication satellite are easily affected by plasma. Even though the radiation shielding on the components can be a way to prevent, the cost will be high. So the appropriate shielding is necessary and the study on space environment is also. In this study spacecraft anomalies will be investigated from low earth orbit to deep space spacecraft and the correlation between spacecraft anomalies and space environment events including space explosion, geomagnetic storms etc is analyzed.

Improvement of Electromagnetic Shielding Structure for Reduction of the Leakage Magnetic Field in WPT System (WPT 시스템의 누설자계 감소를 위한 전자파 차폐구조 개선)

  • Kim, Jongchan;Lee, Seungwoo;Kang, Byeong-Nam;Hong, Ic-Pyo;Cho, In-Kui;Kim, Nam
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.1
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    • pp.61-68
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    • 2017
  • In this paper, we propose an improved magnetic field shielding structure to reducing the magnetic field generated in the wireless power transfer system operating at a low frequency band. The proposed structure consists of the magnetic material and the conductive material, magnetic field cancelling effect for power transfer is minimized while improving the leakage magnetic field cancelling effect by optimizing the various design parameters in the proposed structure. We analyzed and verified the efficiency of the wireless power transfer system and the reduction effect of the leakage magnetic field through computer simulation and measurement. Analysis results show that power transfer efficiency of the wireless power transfer system utilizing the proposed structure is 77 %, which is maintained at the conventional power transfer efficiency. In addition, compared with the structure maintaining high power transfer efficiency, leakage magnetic field strength is reduced to 29~37 % at the nearest point.

Analysis of ELF Magnetic Field Reduction Ratio on Passive Loop Using Scale Down Model of Transmission Line (축소 모델을 이용한 수동 루프 송전선 자기장 저감율 분석)

  • Cho, Yeun-Gyu;Myung, Sung-Ho;Lee, Jae-Bok;Chang, Sug-Hun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.12 s.115
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    • pp.1231-1239
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    • 2006
  • In this research magnetic field reduction effect of each passive loop was analyzed by using the scale down models of transmission lines. This paper examined magnetic field reduction effect of the passive loop that will be applied to actual facility through the experiment, which is about double vertical transmission line and horizontal transmission line. Consequently, by confirming the fact that magnetic field reduction effect can be obtained to 50 % by passive loop without reactive compensation, we insured technology about application of passive loop. And the case of 3 turns of loop showed two times reduction effect than that of 1 turns of loop in reducing magnetic field. Vertical passive loop is more efficient than horizontal passive loop in the aspect of reducing magnetic field on double vertical transmission lines. What is more, vertical passive loop showed good effect of reducing magnetic field in a far distance as well as in a short distance.

레이저 유기 형광법을 이용한 자기장이 인가된 유도결합플라즈마의 전기장 특성 연구

  • Song, Jae-Hyeon;Kim, Hyeok;Jeong, Jae-Cheol;Hwang, Gi-Ung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.474-474
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    • 2010
  • 현재 반도체시장의 확장으로 인해서 기존의 300mm 웨이퍼에서 450mm의 웨이퍼를 사용하는 공정으로 변화하는 추세이다. 450mm 웨이퍼로 대면적 화되면서 기존 300mm 공정 때보다 훨씬 효율적인 플라즈마 소스 즉, 고밀도이고, 고균등화(high uniformity) 플라즈마 소스를 필요로 한다. 본 논문에서는 고밀도 플라즈마 소스인 유도 결합형 플라즈마(Inductively Coupled Plasma ; ICP)에 축 방향의 약한 자기장을 인가시킨 자화된 유도결합형 플라즈마(Magnetized Inductively Coupled Plasma : MICP)[1]를 제안하여 기존 ICP와의 차이점을 살펴보았다. 실험 방법으로 레이저 유기 형광법(Laser Induced Fluorescence : LIF)[2]을 이용하여 플라즈마 쉬스(Sheath) 내의 전기장을 외부 자기장의 변화에 따라 높이별로 측정하고 그 결과로부터 쉬스의 전기적 특성을 살펴보았다. 플라즈마의 특성상 탐침이나 전극에 전압을 인가하면 그 주위로 디바이 차폐(Debye Shielding)현상이 일어나서 플라즈마 왜곡이 일어난다. 그렇기에 플라즈마, 특히 플라즈마 쉬스의 특성을 파악하기 위해서 레이저라는 기술을 사용하였다. 레이저는 고가의 장비이고 그 사용에 많은 경험지식(know-how)를 필요로 하지만 플라즈마를 왜곡시키지 않고, 플라즈마의 밀도, 온도, 전기장 등 많은 상수(parameter)들을 얻어 낼 수 있다. 또한 3차원적으로 높은 분해능을 가지고 있는 장점이 있다. 강한 전기장이 있는 곳에서 입자들의 고에너지 준위가 전기장의 세기에 비례하여 분리되는 Stark effect[3] 이론을 이용하여 플라즈마 쉬스내의 전기장을 측정하였다. 실험은 헬륨가스 700mTorr 압력에서 이루어졌다. 기판의 파워를 50W에서 300W까지 변화시키면서 기판에 생기는 쉬스의 전기장의 변화를 살펴보았고, 자기장을 인가한 후 동일한 실험을 하여 자기장의 유무에 따른 플라즈마 쉬스의 전기장 변화를 살펴보았다. 실험결과 플라즈마 쉬스의 전기장의 변화는 기판의 파워와 플라즈마 밀도에 크게 의존함을 알았다. 기판의 파워가 커질수록 쉬스의 전기장은 커지고, 기판에 생기는 Self Bias Voltage역시 음의 방향으로 커짐을 확인 하였다. 또한 자기장을 걸어주었을 경우 쉬스의 두께가 얇아짐으로써 플라즈마의 밀도가 증가했음을 확인 할 수 있었다.

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Canine MR Images from 3T Active-Shield MRI System (3T 능동차폐형 자기공명영상 장비로부터 얻어진 개의 자기공명영상)

  • Choe, Bo-Young;Park, Chi-Bong;Kang, Sei-Kwon;Chu, Myoung-Ja;Kim, Euy-Neyng;Lee, Hyoung-Koo;Suh, Tae-Suk
    • Progress in Medical Physics
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    • v.12 no.2
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    • pp.113-124
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    • 2001
  • For veterinary imaging diagnosis, we obtained MR images of the canine brain, spine, kidney and pelvis from 3T MRI system which was equipped with the world first 3T active shield magnet. Spin echo (SE) and fast Spin Echo (FSE) images were obtained from the canine brain, spine, kidney and pelvis of normal and sick dogs using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. In addition, we employed a homemade saddle shaped RF coil. Typical common acquisition parameters were as follows: matrix=512$\times$512, field of view (FOV)=20cm, slice thickness=3 w, number of excitations (NEX)=1. For T1-weighted MR images, we used TR=500 ms, TE=10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE=108 ms. Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.57 system. The high resolution images acquired in this study represent more than a 4-fold increase in in-plane resolution relative to conventional images obtained with a 20 cm field of view and a 5 mm slice thickness. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter The present results demonstrate that the MR images from 3T system could provide better diagnostic quality of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods. Moreover, MRI technique could begin to apply for veterinary medicine in Korea.

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