• Title/Summary/Keyword: Critical current

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Relationship between Critical Thinking Disposition, Clinical Decision Making and Job Satisfaction of Cancer Center Nurses (암전문병원 간호사의 비판적 사고성향, 임상 의사결정능력, 직무만족도에 관한 연구)

  • Jung, Sam-Chul;Jung, Duk-Yoo
    • Journal of Korean Academy of Nursing Administration
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    • v.17 no.4
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    • pp.443-450
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    • 2011
  • Purpose: This study was a descriptive correlation study to increase understanding of, and relationships among critical thinking disposition, clinical decision making and job satisfaction of cancer center nurses. Method: The participants in this study were 150 nurses working in one cancer center located in Gyeonggi Province. The statistic program, SPSS WIN17.0 was used for data analysis and data were analyzed using t-test, ANOVA, and Pearson correlation. Results: The critical thinking disposition of the participants showed statistically significant differences according to areas of practice (F=4.426, p=.005), and current position (F=9.346, p=.000). For clinical decision making of the participants, statistically significant differences were found according to current position (F=10.667, p=.000). Furthermore, for job satisfaction, there were statistically significant differences according to income (F=6.779, p=.002), length of career (F=2.701, p=.033) and current position (F=5.423, p=.005). There were significant positive correlations for critical thinking disposition with clinical decision making, and with job satisfaction. Conclusions: The results of the study indicate that to improve clinical decision making and job satisfaction of cancer center nurses, it is necessary to increase critical thinking disposition. To make this change, appropriate programs are needed to increase critical thinking and clinical decision making of general cancer center nurses.

A study on the magnetic properties of high Tc superconductor $Y_{1-x}Yb_xBa_2Cu_3FyOy$ (고온 초전도체 $Y_{1-x}Yb_xBa_2Cu_3FyOy$의 자기적 성질에 관한 연구)

  • 김재욱;김채옥
    • Electrical & Electronic Materials
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    • v.9 no.6
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    • pp.578-583
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    • 1996
  • The magnetic properties have been investigated for the system of $Y_{1-x}$Yb$_{x}$Ba$_{2}$Cu$_{3}$F$_{y}$O$_{y}$ with x=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5. In the magnetic hysteresis measurements, the values of the magnetic critical current densities are in the range of 10$^{4}$-10$^{5}$ A/cm$^{2}$ at the maximum external field 1.4 T. The upper critical field is over 100 T. The critical current density is estimated by the magnetization width .DELTA.M through the Bean critical state model. As the field strength is increased, the .DELTA.M diminishes slowly. The .DELTA.M for the fluorinated sample also decreases slowly with increasing field. It is considered that the large J, value results from this type is due to enhanced pinning center in grain boundary.y.ary.y.

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The Computer Simulation on the Characteristics of the Non-Inductive Superconducting Fault Current Limiter (무유도성 초전도전류제한기의 특성 해석 및 컴퓨터 시뮬레이션)

  • 주민석;이상진;오윤상;고태국
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.43 no.7
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    • pp.1050-1060
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    • 1994
  • This paper is a study on the computer simulation of the characteristics of the superconducting fault current limiter. Input variable parameters are apparent power, load resistance value, line resistance value and so on. Initial fault current 2 times larger than the trigger current is required to reduce the switching time of SFCL. The propagation velocity increases abruptly, the transport current is several times larger than the ciritical current. In this paper, the switching time is calculated to be 323$\mu$ sec, and the initial fault current is 19 times larger than the critical current. Because the trigger coils are bifilar winding, they have little impedance in superconducting state. After fault occurred, the limiting coil acts as a superconducting reactor and the trigger coils quench at a critical current. Without the SFCL in the circuit, fault current after the load impedence is shorted might be increased to 1100A. The fault current is, therefore, successfully limited by the superconducting limiting coil to 100A determined by the coil inductance.

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Non-contact critical current measurement of superconducting coated conductor using Hall Probe (Hall Probe를 이용한 초전도선재의 비접촉 임계전류 측정 방법)

  • Kim, Ho-Sup;Oh, Sang-Soo;Lee, Nam-Jin;Ha, Dong-Woo;Baik, Seung-Kyu;Ko, Rock-Kil;Ha, Hong-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.12-12
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    • 2010
  • The hall probe measurement system was used to measure the critical current distribution of superconducting coated conductor. The system consists of reel to reel moving apparatus, 7 array hall probe, a rotary encoder and permanent magnet. The magnetic field profile across the width of superconducting coated conductor using Bean's critical state model was calculated. The effect of various parameters of the formulas on the magnetic field distribution and the effect of shape and size of artificial defects, which were formed on the surface of SmBa2Cu3O7-d(SmBCO) coated conductor using laser marking system, on the hall probe magnetic field signal of the hall probe measurement system was investigated.

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Effective Charge Number and Critical Current Density in Eutetic SnPb and Pb Free Flip Chip Solder Bumps (SnPb와 무연 플립칩 솔더의 유효전하수와 임계전류밀도)

  • Chae, Kwang Pyo
    • Journal of Welding and Joining
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    • v.23 no.5
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    • pp.49-54
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    • 2005
  • The effective charge number and the critical current density of electromigration in eutetic SnPb and Pb Free $(SnAg_{3.8}Cu_{0.7)$ flip chip solder bumps are studied. The effective charge number of electromigration in eutectic SnPb solder is obtained as 34 and the critical current density is $j=0.169{\times}({\delta}_{\sigma}/{\delta}_x})\;A/cm^2,\;where\;({\delta}_{\sigma}/{\delta}_x})$ is the electromigration-induced compressive stress gradient along the length of the line. While the effect of electromigration in Pb free solder is much smaller than that in eutectic SnPb, the product of diffusivity and effective charge number $DZ^{\ast}$ has been assumed as $6.62{\times}10^{-11}$. The critical length for electromigration are also discussed.

Effect of External Reinforcement on Stress/strain Characteristics of Critical Current in Ag Alloy Sheathed Bi-2212 Superconducting Tapes (Bi-2212 초전도 테이프에서 임계전류의 응력/변형률 특성에 미쳐는 외부강화의 영향)

  • ;K. Katagiri
    • Progress in Superconductivity and Cryogenics
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    • v.3 no.1
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    • pp.6-10
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    • 2001
  • Stress/stram dependencies of the critical current $I_c$ in AgMgNi sheathed multifilamentary Bi(2212) superconducting tapes were evaluated at 77K, 0T. The external reinforcement was accomplished by soldering Ag-Mg tapes to sin91e side or both sides of the sample. With the external reinforcement. the strength of tapes increased but $I_c$, decreased The $I_c$, degradation characteristic according to the external reinforcement was improved markedly in terms of the stress although it appeared less rectal.table on the basis of the strain. Effects of external reinforcement were discussed in a viewpoint of monitoring sensitivity of cracking in superconducting filaments by considering n-value representing the transport behavior of the current. It is closely associated with the location of them relative to the voltage-monitoring region in the tape.

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Over critical current characteristics of HTS tapes (고온초전도 선재의 과전류 통전 특성)

  • 임성우;황시돌;최용선;최효상;현옥배;유재무
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.241-244
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    • 2002
  • We investigated over critical current characteristics of HTS tapes fabricated by KIMM. The critical current (Ic) of the HTS tapes was 68A/cm. In order to acquire over current I-V characteristics of HTS tapes, we applied AC that is 2-7 times of Ic to these tapes. When applied AC whose peak value is twice of Ic, we found out that total resistance of HTS tapes aid not change. In case of 3 times of Ic, resistances of HTS tapes began to increase slowly. However, superconducting regions of them were maintained stably in this condition. In addition, 280 $A_{peak}$was applied, superconducting regions began to be decreased gradually. Finally, 0.62m$\Omega$ of resistance was measured in HTS tapes which was applied AC correspond to 7 times of Ic at first cycle.

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Redox Reaction on Polarization Curve Variations of Polymer with Enzymes

  • Park, Chil-Nam
    • Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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    • v.4 no.3
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    • pp.165-171
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    • 2000
  • Experiments were carried out to measure variations in the oxidation potential and current density using the polarization curves of polycarbonate. The results were then examined to identify the influences affecting the oxidation potential related to various conditions, such as temperature, pH, and oxydase(citrate and lipase). The lines representing the active anodic and cathodic dissolution shifted only slightly in the potential direction relative to temperature, pH, and the effect of the enzyme. The Tafel slope for the anodic and cathodic dissolution was determined such that the reversibility polarization was indicated as being effected by various conditions. The slope of the polarization curves describing the active-to-passive transition region shifted noticeably in their direction. Also, by varying the conditions, the optimum conditions for the most ready transform were identified, including temperature, pH, oxidation rate, and resistance of oxidation potential. The critical oxidation sensitivity(I(sub)r/I(sub)f) of the anodic current density peak and maximum passive current density was also determined, which is used in measuring the critical corrosion sensitivity of a polycarbonate.

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Measurement and Analysis of the Flux Profiles of the Coated Conductors using Magneto-optical Image and Scanning Hall Probe (Coated conductor에서 magneto-optical image와 scanning hall probe를 이용한 flux profile의 측정 및 분석)

  • Lee, H.Y.;Kwak, K.S.;Rhyee, J.K.;Yoo, J.;Youm, D.
    • Progress in Superconductivity
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    • v.11 no.2
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    • pp.128-134
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    • 2010
  • The magnetic flux profiles in SmBCO and YBCO coated conductors(CC) in the presence of the external field were comparatively investigated by magneto-optic image and scanning hall probe measurements. The current distributions calculated by using the inversion method from measured field profiles show that the decrease of current densities near the edges of SmBCO CC is more significant than those of YBCO CC. Through the comparison of the numerical analysis based on Kim's critical state model and the Brandt and Indenbom's solution, we found that this feature is related to their different field dependant properties of the critical current densities.