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RISS 인기검색어
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- 저자 : SEO DONGHYUN (검색결과 2 건)
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Design of compact integrated antennas for wirelss headset application
SEO DONGHYUN 한양대학교 대학원 2008 국내석사
Miniaturization of an antenna is a key issue for headset application in order to integrate antenna with a module. In this thesis, the novel compact antennas for wireless headset are proposed. Before going with the details of an antenna design, basic theories about a helical antenna, important characteristics of an inverted-F antenna (IFA) and antenna miniaturization technologies are reviewed. A PCB integrated helical antenna and an integrated modified inverted-F antenna (IFA) on LTCC module operating in 2.4 GHz Bluetooth band are proposed. The first antenna is a two-wire helical type with shorting pin on the circuit board. To obtain the required bandwidth, modified two-wire helical technique is utilized. The other antenna is a modified IFA which is integrated with LTCC module. In order to obtain the enough bandwidth, modified shorting strip is used. The proposed antennas provide good return loss and radiation characteristics in the frequency band of interest. Effects of human head on the antenna performance are also discussed.
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Seo, Donghyun 서울시립대학교 일반대학원 2019 국내석사
강유전성을 갖는 PVDF-TrFE thin film은 저비용, 저온, 용액 공정이 가능하여 Energy harvesting 소자, 압전센서, FeRAM 등 많은 전자소자에 응용될 수 있다. 하지만 갈수록 소형화되는 전자소자들에 맞추어 더 높은 값의 잔류분극을 갖는 강유전체 물질이 필요하게 되었다. 일반적으로 잔류분극값을 높이려면 Coervice field 또한 증가하게 되는데 높은 Coervice field 를 갖는 강유전체 필름은 전자소자에 응용하기에 많은 문제점을 갖고 있다. 본 연구에서는 PVDF-TrFE 파우더를 유기용매 (MEK, DMF) 에 녹여 만든 용액에 소량의 은과 토르말린을 첨가하여 스핀코팅 방식으로 손쉽게 Coervice voltage 의 변화 없이 PVDF-TrFE 복합필름의 잔류분극 값을 높였다. 증가한 잔류분극 값은 은과 토르말린을 첨가한 복합필름에서 같은 방식으로 만든 PVDF-TRFE 필름에 비해 각각 최대 30.3%, 14.02% 증가함을 확인하였다. 또한 XRD 분석을 통해 첨가된 불순물들이 PVDF-TrFE 필름의 결정구조를 크게 변화시키지 않음을 확인하였다. P(VDF-TrFE) thin film with ferroelectric properties can be applied to many electrical devices, such as energy harvesting device, piezoelectric sensor, ferroelectric random access memory (FeRAM), etc., as it enables low-cos, low-temperature, and solution process. However, as these electrical devices become smaller and smaller, researchers have to find another ferroelectric materials which have a large remanent polarization(Pr). In general, if some ferroelectric materials have a large remanent polarization, it also have a large coercive field or voltage(Ec). As a large coercive voltage is disadvantage for practical devices applications, it is hard to solve the problem. In this study, I fabricated P(VDF-TrFE) composite films by spin-coating and solution methods adding small amount of silver nanoparticle(Ag) and tourmaline power. The solution was made by dissolving P(VDF-TrFE) powder in an organic solvent (MEK, DMF). And I was able to obtain the P(VDF-TrFE) composite films with increased polarization in a simple way, without changing a coercive voltage. I observed that a remanent polarization of the P(VDF-TrFE) composite films adding Ag and tourmaline was increased up to 30.3% and 14.02%, respectively, over the P(VDF-TrFE) film made by a same way. Also, I confirmed that added impurities do not significantly change the crystalline structure of the film through a XRD analysis.
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