• Title/Summary/Keyword: TiB2

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The Trapped Field Decay of YBCO Superconductor Composite with Times (시간 경과에 따른 YBCO 초전도 복합체의 포획 자기장 감쇄)

  • Lee, M.S.;Jang, G.E.;Jun, B.H.;Ha, D.W.;Son, M.H.;Han, Y.H.;Park, B.J.
    • Progress in Superconductivity
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    • v.12 no.2
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    • pp.82-87
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    • 2011
  • We studied the trapped field properties of bulk Y-Ba-Cu-O superconductors by applying 3 T of the permanent or $Nb_3Ti$ superconducting magnet. The 28 mm circular type of YBCO bulk superconductor was prepared and then hole at the center of bulk, parallel to the c-axis, was mechanically drilled. Typical size of hole in YBCO bulk was 10 mm in diameter. In order to examine the trapped field variation in terms of different impregnated materials, a hole in YBCO bulk was filled with resin and indium respectively. The trapped field decay due to flux flow was determined in terms of time. Our preliminary result indicates the trapped field value measured on the YBCO without hole after 30 minute by applying 3 T, was 6,500 G, which is much higher than that, 4,500 G, measured on YBCO with hole. Also, we confirmed that the tendency of a trapped field decrement with time was almost the same regardless of the impregnated materials in YBCO.

A Study on the Development of a Control and Monitoring System for Impressed Current Corrosion Protection (선박용 차세대 외부전원방식 제어 및 감시 시스템 UNIT 개발)

  • Kim, Y.B.;Kim, B.Y.;Suh, J.H.;Kim, J.W.
    • Journal of Power System Engineering
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    • v.10 no.2
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    • pp.104-110
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    • 2006
  • Corrosion has been around for all of recorded history. Cathodic protection is the electrical solution to the corrosion problem. Corrosion is not exactly a new topic. It has been around since the beginning of time. Corrosion is simply the loss of material resulting from current leaving a metal, following through a medium, and returning to the metal at a different point. Corrosion takes many forms and has various names, such as oxidation, rust, chemical, and bacteria action. Regardless of the agent, all corrosion is the result of electrical current flow. Various methods are used to treat corrosion or to try to prevent ti. Some of these include chemical treatment. coatings, and electrical current. Especially, proper impressed current can stop corrosive action on the protected surface. In this article, we introduce the Impressed Current Cathodic Protection (ICCP) Control and monitoring system developed by ourselves. The ICCP system is composed of a power supply, anode, reference electrode and controller. The main issue is to control the current flow on the desired value such that it is possible to force a metal to be more negative(cathodic) than the natural state. From the this process, we can achieve the cathodic protection. Of course, in the developed system, the necessary functions are possessed, such as remote control, monitoring of system fault detection etc. Some experimental results show the system performance and usefulness.

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An Application of AHP for the Selection of Optimum Product of BWTS for over 10,000 TEU Container Ship (AHP 기법을 이용한 10,000 TEU 이상 컨테이너선에 적용되는 선박평형수 처리장치 최적제품 선정에 관한 연구)

  • Lee, Sang-Won;Kim, Dong-Joon;Seo, Won-Chul
    • Journal of the Society of Naval Architects of Korea
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    • v.52 no.5
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    • pp.395-406
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    • 2015
  • The Ballast Water Treatment System was developed to prevent the unintended transport of unwanted organisms from one region to another as demanded by the IMO (International Maritime Organization). Although various types of BWTS in the world have been developed until now and applied to various ships, there has been no systematic basis for its selection and installation. Currently, the system selection and installation are as per ship owner’s suggestion or by easy installation point of view by the shipyard. In order to organize, systemize and solve problems related to the selection and installation of BWTS, a definitive study has been performed to come up with the best alternative to derive value and criteria which were to be met for vessels which are to be equipped with BWTS. Multiple criteria were compared alongside each other during the course of this study. Accordingly an AHP (Analytic Hierarchy Process) analysis method for A, B and C companies were done for container ships with size 10,000 TEU and above. Equipment type for “A” company is “Filter, UV & TiO2” combined type. For “B” company it is “Filter & UV” combined type. Finally for “C” company it is “Electrolysis” type. Henceforth, the results of this study aims to come up with the optimum way to select the best and the most suitable BWTS for a certain vessel.

Performance Analysis of Access Channel Decoder Implemeted for CDMA2000 1X Smart Antenna Base Station (CDMA2000 1X 스마트 안테나 기지국용으로 구현된 액세스 채널 복조기의 성능 분석)

  • 김성도;현승헌;최승원
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.2A
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    • pp.147-156
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    • 2004
  • This paper presents an implementation and performance analysis of an access channel decoder which exploits a diversity gain due to the independent magnitude of received signals energy at each of antenna elements of a smart antenna BTS (Base-station Transceiver Subsystem) operating in CDMA2000 1X signal environment. Proposed access channel decoder consists of a searcher supporting 4 fingers, Walsh demodulator, and demodulator controller. They have been implemented with 5 of 1 million-gate FPGA's (Field Programmable Gate Array) Altera's APEX EP20K1000EBC652 and TMS320C6203 DSP (digital signal processing). The objective of the proposed access channel decoders is to enhance the data retrieval at co]1-site during the access period, for which the optimal weight vector of the smart antenna BTS is not available. Through experimental tests, we confirmed that the proposed access channel decoder exploitng the diversity technique outperforms the conventional one, which is based on a single antenna channel, in terms of detection probability of access probe, access channel failure probability, and $E_{b/}$ $N_{o}$ in Walsh demodulator.r.r.

The Mixing Ratio Effect of Insert Metal Powder and Insert Brazing Powder on Microstructure of the Region Brazed on DS Ni Base Super Alloy (일방향응고 Ni기 초내열합금 천이액상화산접합부의 미세조직에 미치는 모재와 삽입금속 분말 혼합비의 영향)

  • Ye Chang-Ho;Lee Bong-Keun;Song Woo-Young;Oh In-Seok;Kang Chung-Yun
    • Journal of Welding and Joining
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    • v.23 no.6
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    • pp.99-105
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    • 2005
  • The mixing ratio effect of the GTD-111(base metal) powder and the GNI-3 (Ni-l4Cr-9.5Co-3.5Al-2.5B) powder on TLP(Transient Liquid Phase) bonding phenomena and mechanism was investigated. At the mixing ratio of the base metal powder under $50wt\%$, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid insert metal was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solid phases in the bonded interlayer grew epitaxially from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The number of grain boundaries farmed at the bonded interlayer corresponded with those of base metal. At the mixing ratio above $60wt\%$, the base metal powder melted only at the surface of the powder and the amount of the base metal dissolution was also less at the initial time. Nuclear of solids firmed not only from the base metal near the bonded interlayer but also from the remained base metal powder in the bonded interlayer. Finally, the polycrystal in the bonded interlayer was formed when the isothermal solidification finished. When the isothermal solidification was finished, the contents of the elements in the boned interlayer were approximately equal to those of the base metal. Cr-W borides and Cr-W-Ta-Ti borides formed in the base metal near the bonded interlayer. And these borides decreased with the increasing of holding time.

Effect of CeO2 on piezoelectric properties of PSN-PZT ceramics for a hypersonic sound speaker application (지향성 스피커용 PSN-PZT 세라믹스의 압전 특성에 미치는 CeO2 첨가 효과)

  • Choi, J.B.;Song, K.H.;Kim, H.J.;Hwang, S.I.;Yoo, K.S.
    • Journal of Sensor Science and Technology
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    • v.17 no.2
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    • pp.127-132
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    • 2008
  • The effect of $CeO_2$ as a sintering additive on the microstructure and the piezoelectric property of yPb$(Sb_{0.5}Nb_{0.5})O_3$-(1-y)Pb$(Zr_{0.52}Ti_{0.48})O_3$ ($0{\leq}y{\leq}0.1$, PSN-PZT) for a hypersonic sound speaker (HSS) application was investigated. The samples were sintered at $1250^{\circ}C$ for 2 h. The crystal structure and surface morphology of the samples were examined using XRD and FE-SEM, respectively. Study on the influence of $CeO_2$ additives on the dielectric and piezoelectric properties indicated that the $CeO_2$-added PSN-PZT system had a high piezoelectric properties. The optimized results of ${\varepsilon}_r=1209$, $K_p$=52% $d_{33}$=351(pC/N) and $Q_m$=1230.16 were obtained at 0.4 wt.% $CeO_2$-added PSN-PZT.

Microstructure properties with variation of doped amount $Pr_{2}O_{3}$ of BSCT ceramics ($Pr_{2}O_{3}$ 첨가량에 따른 BSCT 세라믹의 미세구조 특성)

  • Noh, Hyun-Ji;Lee, Sung-Gap;Park, Sang-Man;Yun, Sang-Eun;Kim, Ji-Eun;Lee, Young-Hie
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1283-1284
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    • 2007
  • The barium strontium calcium titanate((Ba,Sr,Ca)$TiO_3$) powders prepared by the sol-gel method and $MnCO_3$ as acceptor were mixed oxide method. The microstructure was investigated with variation of $Pr_{2}O_{3}$ amount. The BSCT powder and $Pr_{2}O_{3}$ were mixed with organic vehicle(Ferro. B75001). BSCT thick films were fabricated by the screen-printing method on alumina substrates. The bottom electrode was Pt and upper electrode was Ag, respectively. All BSCT thick films were sintered at $1420^{\circ}C$, for 2h. The result of the differential thermal analysis(DTA), exothermic peak at around $654^{\circ}C$ due to the formation of the polycrystalline perovskite phase. In the X-ray diffraction(XRD) patterns, all BSCT thick films showed the typical perovskite polycrystalline structure and no pyrochlore phase was dbserved. The microstructure investigated by scanning electron microscope(SEM). Pore and grain size of BSCT thick films were decreased with increasing amount of $Pr_{2}O_{3}$ dopant. And the average grain size and thickness of BSCT thick films doped with 0.1 mol% $Pr_{2}O_{3}$ was $3.09{\mu}m$, $60{\mu}m$, respectively. The relative dielectric constant decreased and dielectric loss decreased with increasing amount of $Pr_{2}O_{3}$ dopant, the values of the BSCT thick films no doped with $Pr_{2}O_{3}$ were 7443 and 4 % at 1 kHz, respectively.

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Interaction between RuO2 and Carbon Nanotubes - Photoemission and X-ray Absorption Study

  • Lee, Seung-Youb;Kim, Yoo-Seok;Jeon, Chel-Ho;Ihm, Kyu-Wook;Kang, Tai-Hee;Park, Chong-Yun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.567-567
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    • 2012
  • Since the carbon nanotubes (CNTs) have extraordinary material properties, many researchers are trying to make a practical application in various fields [1]. In particular, the high surface area of CNTs was fascinated for nano-template on the catalytic system. $RuO_2$ coated CNTs are useful functional nano-composites in many applications, including super capacitors, fuel cells, biosensors, and field emitters. However, the research of interaction between CNTs and $RuO_2$ was not satisfied with various fields [2]. In this study, we will introduce the change of chemical and electrical state of $RuO_2$/CNTs at different temperatures by synchrotron radiation photoemission spectroscopy (SRPES). The t-MWCNTs used in this experiment were grown on the Ni/TiN/Si substrates by chemical vapor deposition. $RuO_2$ of 4-20 nm in thickness was deposited on the t-MWNTs by sputter. The SRPES measurements were carried out at the 4B1 beamline of the Pohang Accelerator Laboratory in Korea. The result of XPS measurement indicates that the deposited $RuO_2$ on the CNTs was reduced into pure Ru at above $300^{\circ}C$. And we confirmed that the effective work function of $RuO_2$/CNTs was decreased with increasing temperature.

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Effects of the Introduction of UV Irradiation and Rapid Thermal Annealing Process to Sol-Gel Method Derived Ferroelectric Sr0.9Bi2.1Ta1.8Nb0.2O9 Thin Films on Crystallization and Dielectric/Electrical Properties (UV 노광과 RTA 공정의 도입이 Sol-Gel 법으로 제조한 강유전성 Sr0.9Bi2.1Ta1.8Nb0.2O9 박막의 결정성 및 유전/전기적 특성에 미치는 영향)

  • 김영준;강동균;김병호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.1
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    • pp.7-15
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    • 2004
  • The ferroelectric SBT thin films as a material of capacitors for non-volatile FRAMs have some problems that its remanent polarization value is relatively low and the crystallization temperature is quite high abovc 80$0^{\circ}C$. Therefore, in this paper, SBTN solution with S $r_{0.9}$B $i_{2.1}$T $a_{1.8}$N $b_{0.2}$$O_{9}$ composition was synthesized by sol-gel method. Sr(O $C_2$ $H_{5}$)$_2$, Bi(TMHD)$_3$, Ta(O $C_2$ $H_{5}$)$_{5}$and Nb(O $C_2$ $H_{5}$)$_{5}$ were used as precursors, which were dissolved in 2-methoxyethanol. SBTN thin films with 200 nm thickness were deposited on Pt/Ti $O_2$/ $SiO_2$/Si substrates by spin-coating. UV-irradiation in a power of 200 W for 10 min and rapid thermal annealing in a 5-Torr-oxygen ambient at 76$0^{\circ}C$ for 60 sec were used to promote crystallization. The films were well crystallized and fine-grained after annealing at $650^{\circ}C$ in oxygen ambient. The electrical characteristics of 2Pr=11.94 $\mu$C/$\textrm{cm}^2$, Ps+/Pr+=0.54 at the applied voltage of 5 V were obtained for a 200-nm-thick SBTN films. This results show that 2Pr values of the UV irradiated and rapid thermal annealed SBTN thin films at the applied voltage of 5 V were about 57% higher than those of no additional processed SBTN thin films. thin films.lms.s.s.

High-Efficiency a-Si:H Solar Cell Using In-Situ Plasma Treatment

  • Han, Seung Hee;Moon, Sun-Woo;Kim, Kyunghun;Kim, Sung Min;Jang, Jinhyeok;Lee, Seungmin;Kim, Jungsu
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.230-230
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    • 2013
  • In amorphous or microcrystalline thin-film silicon solar cells, p-i-n structure is used instead of p/n junction structure as in wafer-based Si solar cells. Hence, these p-i-n structured solar cells inevitably consist of many interfaces and the cell efficiency critically depends on the effective control of these interfaces. In this study, in-situ plasma treatment process of the interfaces was developed to improve the efficiency of a-Si:H solar cell. The p-i-n cell was deposited using a single-chamber VHF-PECVD system, which was driven by a pulsed-RF generator at 80 MHz. In order to solve the cross-contamination problem of p-i layer, high RF power was applied without supplying SiH4 gas after p-layer deposition, which effectively cleaned B contamination inside chamber wall from p-layer deposition. In addition to the p-i interface control, various interface control techniques such as thin layer of TiO2 deposition to prevent H2 plasma reduction of FTO layer, multiple applications of thin i-layer deposition and H2 plasma treatment, H2 plasma treatment of i-layer prior to n-layer deposition, etc. were developed. In order to reduce the reflection at the air-glass interface, anti-reflective SiO2 coating was also adopted. The initial solar cell efficiency over 11% could be achieved for test cell area of 0.2 $cm^2$.

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