• 공업화학
• /
• 제21권5호
• /
• pp.527-531
• /
• 2010

Fe계 metal powder를 이용하여 최적화된 전자파차폐 시트를 제조한 후, 제조된 시트에 physical vapor deposition (PVD)법으로 여러 금속들을 증착시켜 최종 전자파차폐용 시트를 제조하였다. 또한 증착된 금속들의 전자파 효율 특성을 분석하기 위하여 polyvinylidene fluoride (PVdF) 나노섬유 막을 시트로 활용하였다. 전기적 특성을 알아보기 위해 4-point probe로 측정하였으며, energy dispersive spectroscopy (EDS)를 이용하여 제조된 sheet에 금속이 증착되었음을 확인하였다. 차폐효율은 전자파차폐효율측정기를 이용하여 측정하였다. 전기저항은 $1000\;{\AA}$일 때 Cu에서 $641.95{\Omega}{\cdot}cm$로 가장 낮은 저항 값을 나타내었다. 전자파 차폐효율은 증착된 금속의 두께의 증가에 따라 증가되었으며, Cu가 $1000\;{\AA}$으로 증착된 sheet가 최고 효율인 32.5 dB을 나타내었다.

• 대한방사선기술학회지:방사선기술과학
• /
• 제43권5호
• /
• pp.383-388
• /
• 2020

High-energy proton accelerators continue to be increasingly used in medical, research and industrial settings. However, due to the high energy of protons, a large number of secondary radiation occurs. Among them, neutrons are accompanied by difficulties of shielding due to various energy distribution and permeability. So In this study, we propose a shielding method that can shield neutrons most efficiently by using multiple-shielding material used as a decelerating agent or absorbent as well as a single concrete shielding. The flux of secondary neutrons showed a greater decrease in the flux rate when heavy concrete was used than in the case of ordinary concrete, and the maximum flux reduction was observed at the front position when using multiple shields. Multiple shielding can increase shielding efficiency more than single shielding however, As the thickness of the multiple shielding materials increased, the decline in flux was saturated. The mixture material showed higher shielding results than the polyethylene when using boron carbonate.

• 전기학회논문지
• /
• 제64권4호
• /
• pp.623-628
• /
• 2015

In this paper, the shield plate was applied to the wireless power transfer (WPT) system. Then we compared transmission efficiency of WPT system between transmitter and receiver coils. The superconductor coil was applied to transmitter and receiver coils in order to increase the transmission efficiency of WPT. The superconductor coil was more effective to power transmission as its current density was higher than normal conductor coil. Efficiency of WPT between transmitter and receiver coils was changed by a quality of shielding. We used the shielding materials such as glass, iron, steels, aluminum etc. The efficiency of WPT system was depended on the shielding materials of transmitter and receiver coils. As a result, magnetic material such as aluminum, iron reduced the magnetic flux density and the efficiency of WPT. remarkably, but in non-magnetic material such as glass and plastic, the efficiency of WPT was unaffected.

• Nuclear Engineering and Technology
• /
• 제50권3호
• /
• pp.462-469
• /
• 2018

The background spectrum of a $3^{{\prime}{\prime}}{\times}3^{{\prime}{\prime}}$ NaI(Tl) well-type scintillation SILENA detector was measured without shielding, in 6 cm thick lead shielding, and with 2 mm thick electrolytic copper covering the detector inside the lead shielding. The relative remaining background of the lead shield lined with copper was found to be ideal for low-level environmental radioactive spectroscopy. The background total count rate in the (20-2160 KeV) was reduced 28.7 times by the lead and 29 times by the Cu + Pb shielding. The effective reduction of background (1.04) by the copper mainly appeared in the energy range from X-ray up to 500 KeV, while for the total energy range the ratio is 1.01 relative to the lead only. In addition, a strong relation between the full-energy peak absolute efficiency and the detector well height was found using gamma-ray isotropic radiation point sources placed inside the detector well. The full-energy peak efficiency at a midpoint of the well (at 2.5 cm) is three times greater than that on the detector surface. The energy calibrations and the resolution of any single energy line are independent of the locations of the gamma source inside or outside of the well.

• 한국초전도ㆍ저온공학회논문지
• /
• 제17권1호
• /
• pp.40-43
• /
• 2015

Wireless power transfer technology is using the magnetic resonance recently drawing increased attention. It uses the resonance between transmitter and receiver coils to transfer power. Thus, it can improve the transfer distance and efficiency compared with the existing magnetic induction technique. The authors found from the previous study that the application of the superconductor coil to the magnetic resonance wireless power transfer system improved its efficiency. Its application to real life, however, requires the additional study on the effects of adjacent materials. In this study, the two resonance coils made by superconductor coils were used to aluminum and plastic shielding materials was placed between the coils. S-parameters were analyzed according to the position of the shielding material between the transmitter and receiver coils. As a result, the plastic of shielding material had no effect, but the aluminum of shielding material affected the wireless power transfer due to the shielding effectiveness.

• 한국전기전자재료학회논문지
• /
• 제11권1호
• /
• pp.1-6
• /
• 1998

Polyaniline free standing films are prepared by various processing. The properties of these films such as electrical conductivity and electromagnetic shielding efficiency are investigated. The conductivities of films doped with a camphorsulfonic acid and a silver are found to be 170/cm and 190S/cm, respectively, indicating metallic behavior. The films added silver, which are casted from hydrochloric acid and dodecylbenzensulfonic acid, show that the electromagnetic shielding efficiency are obtained 42∼52dB and 46∼56dB in the frequency range of 10MHz∼1GHz, respectively. This suggests that the films added silver, which is casted from dodecylbenzensulfonic acid, can be used as electromagnetic shielding material.

• 전기학회논문지
• /
• 제65권4호
• /
• pp.684-688
• /
• 2016

The magnetic resonance method requires high quality factor(Q-factor) of resonators. Superconductor coils were used in this study to increase the Q-factor of wireless power transfer(WPT) systems in the magnetic resonance method. The results showed better transfer efficiency compared to copper coils. However, as superconducting coils should be cooled below critical temperatures, they require cooling containers. In this viewpoint, shielding materials for the cooling containers were applied for the analysis of the WPT characteristics. The shielding materials were applied at both ends of the transmitter and receiver coils. Iron, aluminum, and plastic were used for shielding. The electric field distribution and S-parameters (S11, S21) of superconducting coils were compared and analyzed according to the shield materials. As a result, plastic shielding showed better transfer efficiency, while iron and aluminum had less efficiency. Also, the maximum magnetic field distribution of the coils according to the shielding materials was analyzed. It was found that plastic shielding had 5 times bigger power transfer rate than iron or aluminum. It is suggested that the reliability of superconducting WPT systems can be secured if plastic is used for the cooling containers of superconducting resonance coils.

• 한국표면공학회지
• /
• 제39권5호
• /
• pp.210-214
• /
• 2006

In order to enhance the electromagnetic shielding efficiency of commercialized cold-rolled steel sheets, we have prepared Ni deposited steel sheets by the electrodeposition method. Surface alloying with Ni and Fe was achieved on a steel sheet by diffusion annealing process. Shielding effectiveness measurement results showed that annealed Ni electrodeposited steel sheets enhanced the shielding efficiency up to about 3 dB in the frequency range of 20 to 200Hz, compared with that of non-deposited steel sheets.

• 공업화학
• /
• 제25권6호
• /
• pp.613-618
• /
• 2014

본 연구에서는 그래핀 옥사이드의 전기적 특성을 향상시키고자 그래핀 옥사이드에 암모니아수 처리를 이용하여 아민화가 이루어진 그래핀 옥사이드를 제조하였다. 그리고, 아민화된 그래핀 옥사이드의 전기적 특성을 평가하고자 이를 필름으로 제조하여 전자파차폐효율을 측정하였다. 암모니아수 처리 농도가 증가함에 따라 그래핀 옥사이드 표면의 질소 관능기가 증가함을 XPS에 의하여 확인하였으며, 또한, 전자파차폐효율 측정 결과 암모니아수 처리된 그래핀 옥사이드의 전자파차폐효율 특성이 우수함을 확인하였다. 21% 암모니아수 농도로 처리한 그래핀 옥사이드는 2950 MHz 이상에서 -5 dB 이상의 전자파차폐효율을 보여주었으며, 이러한 실험 결과들은 질소 관능기가 그래핀 옥사이드 내에 전자전달을 용이하게 하여 흡수되는 전자파 양을 증가시켰기 때문으로 사료된다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
• /
• pp.240-242
• /
• 2000

This study was investigated absorption properties of electromagnetic wave in thermal sprayed Sr-ferrite coatings. The experiment of this study was ; manufactured thermal spraying powder for improving absorption-efficiency, processed for increasing strength of thermal spray coatings, and measured the electromagnetic wave shielding efficiency. This study was obtained excellent absorption-efficiency by thermal sprayed Sr-ferrite coatings.