• Title/Summary/Keyword: Resistivity-temperature relation

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Effect of Preparation Conditions on Tc, Jc in the ($Bi_{1-x}Pb_{x}$)$_2$$Sr_2$$Ca_2$$Cu_{3.6}$$O_{y}$ Superconductors (($Bi_{1-x}Pb_{x}$)$_2$$Sr_2$$Ca_2$$Cu_{3.6}$$O_{y}$ 초전도체의 제작조건에 따른 Tc, Jc의 영향)

  • 황교영;조한대;이서웅;박용필;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1990.10a
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    • pp.31-35
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    • 1990
  • In the ($Bi_{1-x}Pb_{x}$)$_2$$Sr_2$$Ca_2$$Cu_{3.6}$$O_{y}$ (x=0∼0.5) superconductors, DTA and XRD-pattern analyses were performed to obviousely define optimal calcining and sintering temperature. And, understanding behaviors of High-Tc phase with preparation condition of superconductors, that is, calcining and sintering temperature, sintering time, and variation of Pb contents, in order to make single phase of superconductor, microstructure and its composition were analyzed with SEM, XRD, and EDAX. continuously, the cause of phase transition was define with synthetically studying mutural relation between measured electrical resistivity and current density. Also, in order to design enhancement of critical current density, Jc required for realization, samples varied with pressing condition were made, and measured its, Jc.

Characterization of Cesium Assisted Sputtering Process Using Design of Experiment (실험계획법을 이용한 세슘보조 스퍼터링 공정의 특성분석)

  • Min, Chul-Hong;Park, Sung-Jin;Yoon, Neung-Goo;Kim, Tae-Seon
    • Journal of the Korean institute of surface engineering
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    • v.40 no.4
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    • pp.165-169
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    • 2007
  • Compared to conventional Indium Tin Oxide (ITO) film deposition methods, cesium (Cs) assisted sputtering offers higher film characteristics in terms of electrical, mechanical and optical properties. However, it showed highly non-linear characteristics between process input factors and equipment responses. Therefore, to maximize film quality, optimization of manufacturing process is essential and process characterization is the first step for process optimization. For this, we designed 2 level design of experiment (DOE) to analyze ITO film characteristics including film thickness, resistivity and transmittance. DC power, pressure, carrier flow, Cs temperature and substrate temperature were selected for process input variables. Through statistical effect analysis methods, relation between three types of ITO film characteristics and five kinds of process inputs are successfully characterized and eventually, it can be used to optimize Cs assisted sputtering processes for various types of film deposition.

The relation of structural transition, thermal and electrical stability deintercalation of Li- CICs(II) : For Li-EaGDICs and Li-EGDICs (Li-CICs의 Deintercalation에 따른 구조변이와 열적, 전기적 안정성과의 관계(II) : Li-EaGDICs와 Li-EGDICs에 관하여)

  • Oh, Won-Chun;Park, Chung-Oh;Back, Dae-Jin;Ko, Young-Shin
    • Analytical Science and Technology
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    • v.9 no.1
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    • pp.43-51
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    • 1996
  • We have discussed on the deintercalation process of Li-EaGICs and Li-EGICs synthesized under pressure and temperature by spontaneous oxidation reaction of those compounds based on the results of X-ray diffraction, thermal analysis and electrical specific resistivity analysis. According to the results of the X-ray analysis for the intercalation process, we have found that the stage 1 for Li-EaGICs and Li-EGICs were not completly formed, but their lower stages were formed mainly. And from this results of the deintercalation process, we have found that the deintercalation process did not occur any more after 4 weeks, and the Li-EGDICs have more residual lithium metals than LiEaGDICs between the graphite interlayers. According to the thermal decomposition analysis, Li-two compounds had included very hard exothermic reaction. And we have found that these compounds did not occrurred deintercalation reaction above $400^{\circ}C$. According to the results of the electrical specific resistivity measurements, Li-EGDICs have relatively lower electrical specific resistivity than Li-EaGDICs, and Li-EaGDICs showed a formation of the ideal curve. From these results, we can suggest that Li-EaGDICs have a better properties as an anode material secondary than Li-EGICs.

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The evolution of Magnetic fields in IntraClusterMedium

  • Park, Kiwan;Ryu, Dongsu;Cho, Jungyeon
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.1
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    • pp.49.2-49.2
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    • 2015
  • IntraCluster Medium (ICM) located at the galaxy cluster is in the state of very hot, tenuous, magnetized, and highly ionized X-ray emitting plasmas. High temperature and low density make ICM very viscous and conductive. In addition to the high conductivity, fluctuating random plasma motions in ICM, occurring at all evolution stages, generate and amplify the magnetic fields in such viscous ionized gas. The amplified magnetic fields in reverse drive and constrain the plasma motions beyond the viscous scale through the magnetic tension. Moreover, without the influence of resistivity viscous damping effect gets balanced only with the magnetic tension in the extended viscous scale leading to peculiar ICM energy spectra. This overall collisionless magnetohydrodynamic (MHD) turbulence in ICM was simulated using a hyper diffusivity method. The results show the plasma motions and frozen magnetic fields have power law of $E_V^k{\sim}k^{-3}$, $E_M^k{\sim}k^{-1}$. To explain these abnormal power spectra we set up two simultaneous differential equations for the kinetic and magnetic energy using an Eddy Damped Quasi Normal Markovianized (EDQNM) approximation. The solutions and dimensions of leading terms in the coupled equations derive the power spectra and tell us how the spectra are formed. We also derived the same results with a more intuitive balance relation and stationary energy transport rate.

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The Effects of $Sb_2O_3$ on the Radiation Properties of a Far-Infrared in Semiconducting PTC Thermistor (반도성 PTC 서미스터의 원적외선 방사특성에 미치는 $Sb_2O_3$의 영향)

  • Cho, H.S.;Song, M.J.;Shin, Y.D.;Jang, S.H.;Park, C.B.
    • Proceedings of the KIEE Conference
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    • 1991.11a
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    • pp.278-281
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    • 1991
  • 1) The specimen with 0.175[mol%] of additive $Sb_2O_3$ was minute and didn't appear porosity. The relation between the ratio of resistivity at $160^{\circ}C$ to that at $121^{\circ}C$ of the specimen with 0.175[mol%] of additive $Sb_2O_3$ was $3{\times}10^4$ and it's great value from among specimens. 2) The curie temperature of the specimen with 0.2 [mol%] of additive $Sb_2O_3$ was $140^{\circ}C$ AND it's great value from among specimens and those of other were $121^{\circ}C$ in all therefore, the specimen with above 0.2[mol%] of additive $Sb_2O_3$ is not match for PTCR 3) The variation of radiation properties of the specimen with 0.2[mol%] of additive $Sb_2O_3$ was very steep in the range of far-infrared $5{\sim}10[{\mu}m]$ but radiation percentage was very high of 0.92 in the range of $10[{\mu}m]$.

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The relation of structural transition and electrical property by deintercalation of Li-Carbon intercalation compounds (I) : For the formation of Li-GFDICs and Li-PCDICs (리튬-탄소층간화합물의 Deintercalation에 따른 구조변이와 전기적 성질과의 관계(I) : Li-GFDICs와 Li-PCDICs의 생성에 대하여)

  • Oh, Won-Chun;Baek, Dae-Jin;Ko, Young-Shin
    • Analytical Science and Technology
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    • v.8 no.2
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    • pp.131-138
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    • 1995
  • We have discussed on the structural transition and its effect on the electrical property of Li-GFDICs and Li-PCDICs occuring during the deintercalation process of Li-Graphite Fiber Intercalation Compounds(Li-GFICs) and Li-Petroleum Cokes Intercalation Compounds(Li-PCDICs) synthesized under pressure and temperature by spontaneous oxidation by air circulation. The analytical results were obtained by X-ray diffraction and electrical specific resistivity measurements. According to X-ray analysis, we have found that the major stage of Li-GFICs was stage 2 and those of Li-PCICs were stage 1 and stage 2, respectively. And from this results of the deintercalation process, we have found that the deintercalation process did not occur any more after 5th week of Li-GFDICs and after 3rd week of Li-PCDICs. According to the results of the electrical specific resistivity measurements, Li-GFDICs showed little variation to 3rd week and rising in the steady curve after 4th week, while Li-PCDICs showed a rising in the steady curve to 3rd week and a declining curve after 3rd week. Therefore from these results, we can consider that graphite fiber and petroleum cokes as a substrate can be also used as an anode material of battery because they have good intercalation-deintercalation reactivity with lithium.

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Magnetoresistive Effect in Ferromagnetic Thin Films( II) (강자성체 박막(Co-Ni)의 자기-저항효과에 관한 연구(II))

  • Chang, C.J.;Yoo, J.Y.;Nam, S.W.;Son, D.R.
    • Journal of Sensor Science and Technology
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    • v.3 no.1
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    • pp.68-77
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    • 1994
  • Grid type 70Ni-30Co thin films on slide glass at $250^{\circ}C$ has been fabricated to develope. From fabricated sensors using above process, we investigated the relation of temperature, resistivity, line width to magnetoresistance and we obtained the following results after observation of coercive force, saturated magnetization, maxium usable sensitivity, delay time, slew rate, white noise, resolution of the sensors. We confirmed that the $600{\AA}$ thin film at $250^{\circ}C$ formed crystalized magnetic anisotropy spontaneously and the sensor using the thin film had capability of detecting magnetic field with sensitivity of 230 nT. In these devices, the magnetoresistance change was increased linearly in ${\pm}10$ Oe range, and the magnetoresistance effect was increased when the ratio between line width and length was increased. When the devices was soldered using indium, the temperature-resistivity coefficient showed $8{\times}10^{-3}/deg$ and increased during the specific properties as magnetic field sensor were weakened. In this studies, the coercive forces of the films were about 5.1 A/cm and saturated magnetizations were 0.64 T, and the delay time in these devises was $5{\mu}s$ and slew rate showed 0.39 $Oe/{\mu}s$ and white noise was -120 dB.

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Microstructural Characterization for Structural Health Monitoring of Heat-Resisting Rotor Steels (로터용 내열강의 구조 건전성 모니터링을 위한 미세 조직 평가)

  • Kim, C.S.;Byeon, Jae-Won;Park, Ik-Keun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.2
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    • pp.177-183
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    • 2008
  • The typical heat-resisting rotor steels such as 2.25CrMo, 9CrMo and 12CrW steel were experimentally studied in order to understand their materials degradation under high temperature and pressure during the long-term service, and then use the basic studies for the structural health monitoring. In order to monitor the materials degradation, it was conducted by the isothermal aging for 2.25CrMo steel, creep-fatigue for 9CrMo steel and creep for 12Cr steel with the incremental step test. The ultrasonic wave properties, electrical resistivity and coercivity were interpreted in relation to microstructural changes at each material and showed strong sensitivity to the specific microstructural evolution.