• Title/Summary/Keyword: Insertion loss

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A dual-frequency and dual-polarization antenna with enhanced isolation between two ports using mushroom-like EBGs (버섯모양 EBG를 이용하여 두 포트 사이의 고립도를 향상시킨 이중대역 이중편파 안테나)

  • Lee, Dong-Hyun;Kim, Jae-Hee;Jang, Jong-Hoon;Park, Wee-Sang
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.5
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    • pp.70-75
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    • 2007
  • A dual-frequency dual-polarization (DFDP) antenna with high isolation between two ports by embedding $2{\times}1$ mushroom-like electromagnetic bandgap (EBG) cells is proposed. The equivalent circuit of a suspended microstrip line over $2{\times}1$ EBG cells is introduced. The numerical analysis from the equivalent circuit and measured results show that the microstrip line with embedded EBG cells has a distinctive and sharp rejection band and provides near 0 dB insertion loss outside the rejection band. By embedding the EBG cells under feedlines of a conventional DFDP antenna, the isolation between two ports of the antenna is enhanced more than 20 dB, as compared to that of a conventional DFDP antenna. The proposed DFDP antenna is fabricated and measured. The simulated and measured results show a good agreement. The measured polarization purity and gain of the antenna are 25 dB and 5.77 dBi at lower band, and 35 dB and 7.13 dBi at higher band, respectively.

Performance of CWDM Fabricated by the PLC-AWG Technology (평판형 AWG 기술을 이용한 광대역 파장다중화/역다중화 소자의 제작 및 특성)

  • Moon, H.M.;Kwak, S.C.;Hong, J.Y.;Lee, K.H.;Kim, D.H.;Kim, J.J.;Choi, S.Y.;Lee, J.G.;Lee, J.H.;Lim, K.G.;Kim, J.B.
    • Korean Journal of Optics and Photonics
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    • v.18 no.3
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    • pp.185-189
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    • 2007
  • A novel technology for CWDM (Coarse Wavelength Division Multiplexer) utilizing a PLC (Planar Lightwave Circuit)-AWG (Arrayed Waveguide Grating) fabrication process is proposed. BPM (Beam Propagation Method) Simulation results on the employed parabolic-horn-type input slab waveguide of AWG and the performance of the 20 nm-channel spacing CWDM with flattened passband are presented. Waveguides of $0.75{\triangle}%$ have been used in this experiment and the insertion loss at the peak wavelength is 3.5 dB for a Gaussian spectrum and is 4.8 dB for a flat-top spectrum. The bandwidth at 3 dB is better than 10 nm and 13 nm for Gaussian and flat-top spectra, respectively.

Design of Multilayer Radome with Particle Swarm Optimization (Particle Swarm Optimization을 이용한 다층 구조 레이돔 설계)

  • Lee, Kyung-Won;Hong, Ic-Pyo;Park, Beom-Jun;Chung, Yeong-Chul;Yook, Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.7
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    • pp.744-751
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    • 2010
  • In this paper, the design of multilayer radome within, the insertion loss, -0.3 dB in X-band with PSO was carried out based on two cases. The first is that, deciding material constant of skin and core, each layer thickness of c-sandwich radome with PSO is found and the second is that, deciding material constant and thickness of the skins of both sides, the material constant and thickness of three layers between skins of both sides using PSO is decided. The performance of the designed radome almost agreed with the required performance. It was showed that the radome design applying PSO algorithm is easy and fast and the optimum radome is also designed in combination of the various parameters of radome. From these results, the radome having various performance can be designed except the tedious calculation and also be applied to various radome structure.

A Planar Implementation of a Negative Group Delay Circuit (평면 구조의 마이너스 군지연 회로 설계)

  • Jeong, Yong-Chae;Choi, Heung-Jae;Chaudhary, Girdhari;Kim, Chul-Dong;Lim, Jong-Sik
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.3
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    • pp.236-244
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    • 2010
  • In this paper, a planar structure negative group delay circuit(NGDC) is proposed to overcome the limited availability of the component values required for the prototype lumped element(LE) NGDC design. From the prototype LE circuit analysis, general design equations and the conditions to obtain the NGD are derived and illustrated. Then the LE circuit is converted into the planar structure by applying the transmission line resonator(TLR) theory. As a design example, the LE NGDC and the proposed planar structure NGDC are designed and compared. To estimate the commercial applicability, 2-stage reflection type planar NGDC with -5.6 ns of total group delay, -0.2 dB of insertion loss, and 30 MHz of bandwidth together with 0.1 dB and 0.5 ns of the magnitude and group delay flatness, respectively, for Wideband Code Division Multiple Access(WCDMA) downlink band is fabricated and demonstrated. Also, to show the applicability of the proposed NGDC, we have configured a simple signal cancellation loop and obtained good loop suppression performance.

Treatment of crown-root fracture with a modified crown fragment reattachment technique (변형된 치관부 파절편 재부착술식을 이용한 치관치근파절의 치료)

  • Song, Chang-Won;Song, Min-Ju;Shin, Su-Jung;Park, Jeong-Won
    • Restorative Dentistry and Endodontics
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    • v.35 no.5
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    • pp.395-400
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    • 2010
  • The development of adhesive dentistry has allowed that the crown fragment reattachment can be another option in the treatment of crown fracture. However, additional crown lengthening procedure or extrusion of the tooth may be necessary in the treatment of crown root fracture because subgingival fracture line in close proximity to the alveolar bone leads to challenges for restorative procedure and the violation of the biologic width. This case report presents a modified crown fragment reattachment technique of crown root fracture with pulp exposure, which was done without additional crown lengthening procedures. After the endodontic treatment, the patient was treated using a post insertion and the fragment reattachment technique, which made it possible to preserve the space for the biologic width and maintain a dry surgical field for adequate adhesion through the modification of the fractured coronal fragment. Since a coronal fracture was occurred and reattached afterward, it was observed that the coronal fragment was well maintained without the additional loss of periodontal attachment through 2-year follow up.

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.

Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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Fabrication and optical characteristics of 50 ㎓ narrow band pass filter for fiber optical communication using dual ion beam sputtering technique (이중 이온빔 스퍼터링 방식을 사용한 채널 간격 50 ㎓ 광통신용 협대역 투과 필터의 제작 및 특성)

  • 김회경;김명진
    • Korean Journal of Optics and Photonics
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    • v.14 no.3
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    • pp.331-337
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    • 2003
  • This paper represents 50 ㎓ narrow band pass filters for fiber optical communication fabricated by dual ion beam sputtering method. We have analyzed the characteristics of the TA$_2$ $O_{5}$ and $SiO_2$ single layers in order to optimize the process conditions for the 50 ㎓ narrow band pass filters, and controlled the film thickness uniformity to less than 0.1 nm deviation by dual peak spike filter pre-deposition. We designed and fabricated 50 ㎓ narrow band pass filters that consist of 216 layers including 4 cavities based on quarter wave optical thickness. Class substrates with high thermal expansion coefficients were used to reduce the film stress. Anti-reflection coating at the rear side of the substrate was also needed to reduce the optical thickness errors of the Optical Monitoring System caused by multiple beam interference between the front side and the rear side of substrate. The optical characteristics of this 50 ㎓ narrow band pass filters are insertion loss of 0.40 ㏈, pass band ripple of 0.20 ㏈, and pass bandwidth at -0.5 ㏈ of 0.20 nm. and isolation bandwidth at -25 ㏈ of 0.6 nm, which satisfy specifications of dense WDM system in fiber optical communications.tions.

Design and fabrication of Ka-band high-power, high-efficiency spatial combiner using TM01 mode Transducer (TM01 모드 변환을 이용한 Ka 대역 고출력 고효율 공간 결합기 설계 및 제작)

  • Kim, Hyo-Chul;Cho, Heung-Rae;Lee, Ju-Heun;Lee, Deok-Jae;An, Se-Hwan;Lee, Man-Hee;Joo, Ji-Han;Kim, Hong-Rak
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.21 no.6
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    • pp.25-32
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    • 2021
  • In this study, it proposes a mode converter that is relatively easy to implement and can shorten the transmission line length of the final combining port and it was fabricated and tested by applying it to an 8-way spatial combiner. The proposed mode converter converts the signal converted from the doorknob-shaped circular disk connected to the ground into the TM01 mode by opening it in the circular waveguide. The 8-way waveguide spatial combiner is designed and implemented so that 8 signals input from the H-plane are combined in a circular waveguide at the center, and the final combining mode is TM01. The test results confirmed excellent performance with an insertion loss of less than 0.4dB and a combining efficiency of 95% or more. In addition, it was confirmed that it is suitable for high output by calculating the breakdown voltage and discharge threshold power of the new mode conversion structure through electric field analysis. The results confirmed through this study are expected to be applicable to high-power, high-efficiency SSPA in various fields in the future.

Development of Fiber-end-cap Fabrication Equipment (대구경 광섬유 엔드캡 제작장비 개발)

  • Lee, Sung Hun;Hwang, Soon Hwi;Kim, Tae Kyun;Yang, Whan Seok;Yoon, Yeong Gap;Kim, Seon Ju
    • Korean Journal of Optics and Photonics
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    • v.32 no.2
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    • pp.49-54
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    • 2021
  • In this paper, we design and construct the equipment to manufacture large-diameter optical fiber end caps, which are the core parts of high-power fiber lasers, and we fabricate large-diameter optical fiber end caps using the home-made equipment. This equipment consists of a CO2 laser as a fusion-splice heat source, a precision stage assembly for transferring the position of a large-diameter optical fiber and an end cap, and a vision system used for alignment when the fusion splice is interlocked with the stage assembly. The output of the laser source is interlocked with the stage assembly to control the output, and the equipment is manufactured to align the polarization axis of the large-diameter polarization-maintaining optical fiber with the vision system. Optical fiber end caps were manufactured by laser fusion splicing of a large-diameter polarization-maintaining optical fiber with a clad diameter of 400 ㎛ and an end cap of 10×5×2 ㎣ (W×D×H) using home-made equipment. Signal-light insertion loss, polarization extinction ratio, and beam quality M2 of the fabricated large-diameter optical fiber end caps were measured to be 0.6%, 16.7 dB, and 1.21, respectively.