• Title/Summary/Keyword: RF Via

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Fabrication of IMT-2000 Linear Power Amplifier using Current Control Adaptation Method in Signal Cancelling Loop (신호 제거 궤환부의 전류 제어 적응형 알고리즘을 이용한 IMT-2000용 선형화 증폭기 제작)

  • 오인열;이창희;정기혁;조진용;라극한
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.1
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    • pp.24-36
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    • 2003
  • The digital mobile communication will be developed till getting multimedia service in anyone, any where, any time. Theses requiring items are going to be come true via IMT-2000 system. Transmitting signal bandwidth of IMT-2000 system is 3 times as large as IS-95 system. That is mean peak to average of signal is higher than IS-95A system. So we have to design it carefully not to effect in adjacent channel. HPA(High Power Amplifier) located in the end point of system is operated in 1-㏈ compression point(Pl㏈), then it generates 3rd and 5th inter modulation signals. Theses signals affect at adjacent channel and RF signal is distorted by compressed signal which is operated near by Pl㏈ point. Then the most important design factor is how we make HPA having high linearity. Feedback, Pre-distorter and Feed-forward methods are presented to solve theses problems. Feed-forward of these methods is having excellent improving capacity, but composed with complex structure. Generally, Linearity and Efficiency in power amplifier operate in the contrary, then it is difficult for us to find optimal operating point. In this paper we applied algorithm which searches optimal point of linear characteristics, which is key in Power Amplifier, using minimum current point of error amplifier in 1st loop. And we made 2nd loop compose with new structure. We confirmed fabricated LPA is operated by having high linearity and minimum current condition with ACPR of -26 ㏈m max. @ 30㎑ BW in 3.515㎒ and ACLR of 48 ㏈c max@${\pm}$㎒ from 1W to 40W.

An Application of Artificial Dielectric Substrate for Design of Size-reduced Directional Couplers (방향성결합기의 소형화를 위한 가유전체 기판구조의 응용)

  • Lim, Jong-Sik;Koo, Ja-Kyung;Lee, Jun;Lee, Jae-Hoon;Ahn, Dal
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.7
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    • pp.3169-3175
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    • 2011
  • This paper describes the design of size-reduced directional coupler using the artificial dielectric substrate and its increased effective permittivity. Directional couplers are widely used in measuring RF power indirectly and coupling signal power. Artificial dielectric substrates have higher effective dielectric constant than standard dielectric substrate due to the lots of metalized via-holes, and the increased effective permittivity results in size-reduction of circuits. As a design example, 15dB directional couplers are designed on the standard substrate and artificial dielectric substrate and their size are compared. The size of the directional coupler using the artificial dielectric substrate is only 1/3 of that designed using the standard substrate, while the performances are preserved. In addition, the measured performances of the size-reduced coupler are well agreed with the simulated ones. The measured coupling coefficient, matching, and insertion loss at 2GHz are -14.62dB, -24.1dB, and -0.38dB, respectively.

Inhibitory Effects of Ginsenosides on Glutamate-Induced Swelling of Cultured Astrocytes

  • Seong, Yeon-Hee;Koh, Sang-Bum;Kim, Hack-Seang
    • Journal of Ginseng Research
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    • v.24 no.3
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    • pp.138-142
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    • 2000
  • Effects of ginsenosides (Rb$_1$, Rb$_2$, Rc, Re, Rg$_1$, Rf) on L-glutamate (glutamate)-induced swelling of cultured astrocytes from rat brain cerebral cortex were studied. Following the exposure to 0.5mM glutamate for 1 hr, the intracellular water space (as measured by [$^3$H]O-methyl-D-glucose uptake) of astrocytes increased by about two-fold. Simultaneous addition of ginsenosides Rb$_2$ and Rc with glutamate reduced the astrocytic swelling in a dose-dependent manner. These ginsenosides at 0.5 mg/ml did not affect the viability of astrocytes for up to 24 hr which was determined by a colorimetric assay (MTT assay) for cellular growth and survival. These ginsenosides at 0.3 mg/ml inhibited the increase of intracellular Ca$\^$2+/ concentration ([Ca$\^$2+/]$\_$i/) induced by glutamate. These data suggest ginsenosides Rb$_2$ and Rc prevent the cell swelling of astrocytes induced by glutamate, maybe via inhibition of Ca$\^$2+/ influx.

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Suppressive Effect of CYTG on Collagen Induced Arthritis(CIA) in DBA1/J Mice (CYTG 처방이 콜라겐 유발 관절염 모델에 미치는 효과)

  • Choi, Sung-Wook;Kim, Yong-Chan;Kim, Kyoung-Shin;Kim, Byoung-Soo;Lim, Jong-Soon;Kang, Jung-Soo
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.21 no.1
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    • pp.62-69
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    • 2007
  • To evaluate effect of CYTG on inhibiting the occurrence of arthritis, we performed the experiments including production of inflammatory cytokine and immunoglobulin in collagen arthritis model. The results were obtained as fellows. CYTG group showed inhibitory effect on arthritis incidence than control group for four weeks. Arthritis index of CYTG group reduced compared with control group. In CYTG group, production of cytokines which show suppressive effect on inflammation(IL-2, COX-2) was increased and which promotes inflammation(IL-10) was decreases in spleen. In CYTG group, production of immunoglobulin (IgG-RF) was reduced compared with control, and rate of CD3+CD69+T cell is lower in lymph node and CD4+CD25+ T cell is higher in lymph node and spleen. And synovial infiltration in the knee were observed in the controls (PBS-treated mice), whereas CYTG-treated mice exhibited significantly reduced histologic evidence of destruction and inflammation. So, the histopathological scoring average of CYTG group was 2.5 compared with control group(CIA mice) 4.5. It was thought that our data express high effect via immune system specially through the controling the inflammatory cytokines and immunoglobulins. CYTG could be usefully applied for the prevention and treatment of RA, and also is expected to be clinically helpful on the treatment of RA through modification.

Effect of Isotropic Strain on Properties of Amorphous Magnetic films (아몰퍼스자성박막의 특성에 미치는 등방성 스트레인의 영향)

  • 신광호;김흥근;김영학;사공건
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.478-480
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    • 2001
  • Fe-base amorphous films exhibit large saturation magnetostriction and soft magnetic Properties, which make them suitable for strain sensor applications. Most important material properties for the performance of these elements are the superior soft magnetic properties, such as high permeability and small coercive force, as well as magnetoelastic properties. It is well known that the strain generated in film deposition and/or post-heat treatment processes is one of important material properties, which effects on the soft magnetic properties of the film via magnetoelastic coupling. In this study, the effect of an isotropic strain in plane of magnetic films have been performed experimently. Amorphous films with the composition of (F $e_{90}$ $Co_{10}$)$_{78}$S $i_{l2}$ $B_{10}$ were employed in this study. The film with 5${\mu}{\textrm}{m}$ thick was deposed onto the polyimide substrate with 50${\mu}{\textrm}{m}$ thick by virtue of RF sputtering. The film was subject to post annealing with a static magnetic field with 500Oe magnetic field intensity at 35$0^{\circ}C$ for 1 hour. The polyimide substrate with the film was bonded with an adhesive on PZT piezoelectric substrate with 600${\mu}{\textrm}{m}$ thick in applying voltage of 500V. The change in MH loops of films due to the isotropic strain was measured by using VSM. The coercive force was evaluated from MH loops. It has shown in the results that M-H loops of films are subject to change considerably with a dc voltage, resulting of the magnetization rotation from normal to plane direction as the applied voltage is changed from 500V to 250V.50V.V.

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Dielectric Properties of Continuous Composition Spreaded $BaTiO_3-SrTiO_3$ Thin Films Prepared by Off-Axis RF Magnetron Sputtering System

  • Kim, Yoon-Hoe;Jung, Keun;Yoon, Seok-Jin;Park, Kyung-Bong;Choi, Ji-Won
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.326-326
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    • 2010
  • The dielectric properties of continuous composition spreaded (CCS) $BaTiO_3-SrTiO_3$ (BST) thin filmsgrown at room temperature and annealed at different temperature ($350^{\circ}C$ and $550^{\circ}C$) were investigated. Moreover, electrical properties (leakage current and breakdown voltage) of CCS BST thin films were also investigated. The aluminum top-electrode, sized by $200{\times}200\;{\mu}m2$ and apart from each other by $300\;{\mu}m$, were deposited on the CCS BST thin films by the DC sputtering system. The dielectric properties of the CCS BST thin films were significantly influenced depending on the distance from $BaTiO_3$ and $SrTiO_3$ targets which was attributed to the $BaTiO_3-SrTiO_3$ composition ratio. The maps of dielectric constants and loss tangents were plotted via $1500\;{\mu}m$ - step measuring. The specific points showing the dielectric constant (k: ~300) and loss tangent (tand: ~0.008) at 1 MHz were found.

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Research of Liquid Crystal Alignment on Tantalum Oxide by Using Ion Beam Irradiation (이온빔 조사를 사용한 탄탈륨 산화막에서의 액정 배향에 대한 조사)

  • Lim, Ji-Hun;Oh, Byeong-Yun;Lee, Won-Kyu;Lee, Kang-Min;Na, Hyun-Jae;Park, Hong-Kyu;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.300-300
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    • 2008
  • In this study, the advanced DuoPIGatron-type ion beam (IB) system was applied to inorganic thin film for aligning liquid crystal (LC). LC alignment on $Ta_2O_5$ via IB irradiation was embodied. As a result of IB irradiation, the homogeneously aligned liquid crystal display (LCD) on $Ta_2O_5$ was observed with low pretilt angles. The $Ta_2O_5$ were deposited on indium-tin-oxide coated Coming 1737 glass substrates by rf magnetron sputtering at $200^{\circ}C$. The deposition process resulted in forming very uniform thin film on glass substrates without any defects. To confirm the application of the inorganic alignment on modem display optical devices, we fabricated twisted nematic LCD and measured optical property and response time. As a result of the experiment, the electro optical characteristics of the LCD fabricated by using IB irradiation on $Ta_2O_5$ alignment layer were similar with the other LCD fabricated by using rubbing process.

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Dielectric Properties of $Ta_2O_5-SiO_2$ Thin Films Deposited at Room Temperature by Continuous Composition Spread (상온에서 연속 조성 확산법에 의해 증착된 $Ta_2O_5-SiO_2$ 유전특성)

  • Kim, Yun-Hoe;Jung, Keun;Yoon, Seok-Jin;Song, Jong-Han;Park, Kyung-Bong;Choi, Ji-Won
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.2
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    • pp.35-40
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    • 2010
  • The variations of dielectric properties of $Ta_2O_5-SiO_2$ continuous composition spread thin films prepared by off-axis radio-frequency magnetron sputtering were investigated. The dielectric maps of dielectric constant and loss were plotted via 1500 micron-step measuring. The specific points showing superior dielectric properties of high dielectric constant (k~19.5) and loss (tan${\delta}$<0.05) at 1 MHz were found in area of the distance of 16 mm and 22 mm apart from $SiO_2$ side in $75{\times}25mm^2$ sized Pt/Ti/$SiO_2$/Si(100) substrates.

Effects of Carbon Nitride Surface Layers and Thermal Treatment on Field-Emission and Long-Term Stability of Carbon Nanotube Micro-Tips (질화탄소 표면층 및 열처리가 탄소 나노튜브 미세팁의 전계방출 및 장시간 안정성에 미치는 영향)

  • Noh, Young-Rok;Kim, Jong-Pil;Park, Jin-Seok
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.1
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    • pp.41-47
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    • 2010
  • The effects of thermal treatment on CNTs, which were coated with a-$CN_x$ thin film, were investigated and related to variations of chemical bonding and morphologies of CNTs and also properties of field emission induced by thermal treatment. CNTs were directly grown on nano-sized conical-type tungsten tips via the inductively coupled plasma-chemical vapor deposition (ICP-CVD) system, and a-$CN_x$ films were coated on the CNTs using an RF magnetron sputtering system. Thermal treatment on a-$CN_x$ coated CNT-emitters was performed using a rapid thermal annealing (RTA) system by varying temperature ($300-700^{\circ}C$). Morphologies and microstructures of a-$CN_x$/CNTs hetero-structured emitters were analyzed by FESEM and HRTEM. Chemical composition and atomic bonding structures were analyzed by EDX, Raman spectroscopy, and XPS. The field emission properties of the a-$CN_x$/CNTs hetero-structured emitters were measured using a high vacuum (below $10^{-7}$ Torr) field-emission measurement system. For characterization of emission stability, the fluctuation and degradation of the emission current were monitored in terms of operation time. The results were compared with a-$CN_x$ coated CNT-emitters that were not thermally heated as well as with the conventional non-coated CNT-emitters.

Performance and analysis of wireless power charging system from room temperature to HTS magnet via strong resonance coupling method

  • Chung, Y.D.;Lee, C.Y.;Lee, S.Y.;Lee, T.W.;Kim, J.S.
    • Progress in Superconductivity and Cryogenics
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    • v.18 no.1
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    • pp.41-45
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    • 2016
  • The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.