• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1191-1194
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• 2004

최근 항공우주산업을 비롯한 자동차, 선박, 철강, 건설, 전기, 국방, 금속산업 등 산업의 현장에서 첨단소재들을 널리 사용하고 있으며, 특히 비자성 금속재료에 대한 도전율 특성의 정밀분석이 요구되고 있다. 따라서 본 연구는 비자성 재료의 전기 도전율에 대해 널리 사용되고 있는 3가지의 측정방법을 통하여 정확한 측정과 함께 비교 분석하였으며, 이 측정 방법에 따라 평가된 도전율 측정결과는 0.5 %이내의 정확도에서 일치하고 있는 것으로 나타났다.

• Electrical & Electronic Materials
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• v.6 no.4
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• pp.318-323
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• 1993

본 연구에서는 rf magnetron 스퍼터링으로 (100) 사파이어 기판에 퇴적시킨 YBa$_{2}$Cu$_{3}$$O_{7-x}$박막을 열처리하기 위하여 급속 열처리 방법을 사용하였다. XRD, AES, 그리고 4단자 비저항 측정법을 사용하여 급속 열처리로 형성시킨 초전도체 박막과 기판사이의 상호확산을 조사하였다. 제조된 박막은 91K에서 Tc(onset)를 80K에서 Tc(zero)를 나타내었다. AES 분석 결과, 급속 열처리 방법의 경우 YBa$_{2}$Cu$_{3}$$O_{7-x}$ HTS 박막과 기판사이의 계면에서 항호확산이 감소되는 것을 확인하였다. XRD 분석 결과, 급속 열처리에 의해 형성된 HTS 박막은 주로 c-축이 기판의 표면에 수직인 구조를 가지고 있었다.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.41-47
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• 2002

La/sub 1-x/Ca/sub x/MnO₃ manganese oxide were grown using the floating zone image furnace with halogen lamps as heat source. The growth condition was 4∼6 mm/hr growth rate in air atmosphere, 45∼50 rpm and 20∼25 rpm of rotation rate of feedrod and growing crystal, respectively. Characterization analyses of the crystal were carried out using XRD, SEM, and EPMA. Orientation of crystal was determined using EBSD. The electromagnetic properties were measured with Quantum Design PPMS by 4 point probe method and resulted MR value of 462% at 215 K.

• Electrical & Electronic Materials
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• v.6 no.5
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• pp.407-416
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• 1993

무산소동을 안정화 모재로한 Cu/Nb-Ti 빌렛트를 제작한 다음 간접 열간방식의 압출에 의해 얻어진 봉재를 인발한 후 신선과 열처리를 반복하여 단심 및 다심 Nb-Ti 초전도 선재를 제조하였다. 가공 조직을 조사한 결과, 단심 선재의 경우 Nb-Ti 심의 단면이 균일하게 가공된 것을 확인하였으며 다심선재의 경우는 신선가공에 의하여 다소 불균질한 필라멘트부분이 관찰되었다. 4.2K, 자장하에서 4단자법으로 직선형 단척시료의 임계전류를 측정하여 가공 열처리 조건에 따른 임계전류밀도의 자장특성을 조사하였는데 열처리시간을 길게하고 가공도를 높인 시료일수록 자장하의 임계전류밀도가 높게 나타나는 것을 확인하였다. 4.2K, 5T 자장하에서 각각 4 x $10^{5}$A/$cm^{2}$ 및 2 x $10^{5}$A/$cm^{2}$의 임계전류밀도를 나타내는 Nb-Ti 단심 및 다심 초전도선재를 제작 할 수 있었다.있었다.

• Elastomers and Composites
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• v.35 no.3
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• pp.188-195
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• 2000

The conducting composites were prepared by emulsion polymerization with poly (acrylonitrile-co-butadiene) (NBR) as a matrix and polypyrrole (PPY) as a conducting polymer. Among several surfactants, the electrical conductivity of the composite which was polymerized by dodecyl sodium sulfate (DSS) was the best. The film of composite was prepared by compression molding. The electrical conductivity was measured by 4 probes method as a function of PPY and temperature. When the content of PPY was 25 wt%, the electrical conductivity of composite was increased up to 1.17 S/cm. The percolation threshold showed at the vicinity of 15 wt% PPY content.

• Journal of the Korean Magnetics Society
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• v.7 no.3
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• pp.134-139
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• 1997

Magneto-impedence (MI) were measured in amorphous $Co_{66}Fe_4NiB_{14} Si_{15}$ ribbons at 100 kHz as a function of the angle from ribbon axis. The samples were prepared using etching method, with the angle deviated from ribbon axis, 0$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$ and 90$^{\circ}$. The MI measured in 60$^{\circ}$ sample increased with the increasing magnetic fields. The dip in profile appears at H = 0 above the angle of 30$^{\circ}$. The maximum values of MI and their dips are increased with the cutting angle, but the maximum value of MI decreased at 90$^{\circ}$. The increase of MI with the angle was analyzed in terms of the transverse magnetic permeability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.137-141
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• 2004

저항특성이 다른 ITO박막의 구조특성과 표면특성을 XRD와 AFM(atomic force microscopy), SEM(scanning electron microscopy)을 이용하여 관측하였다. 접촉방식인 4단자 법을 사용하여 ITO박막의 표면전기저항을 측정하였다. 관측된 구조 및 표면특성을 바탕으로 비파괴 비접촉방식을 이용한 근접장 마이크로파 현미경을 이용하여 얻은 ITO박막의 표면저항특성과 비교 연구하였다.

• Journal of Applied Reliability
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• v.8 no.4
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• pp.155-166
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• 2008

PTH cracks are caused by the mismatch of coefficient of thermal expansion(CTE) between polymer and laminated materials, and are one of the main failure mechanisms of multi layer boards. In spite of its importance, it is usually hard to measure or detect them because of its small size and invisibility. To detect PTH cracks more effectively, this paper proposes a theoretical model that can estimate the resistance value from crack size of PTHs. Using four-point probe resistance measurement method, the resistance value of test coupons is measured. Through measured data, we verify the validity of the proposed theoretical model and set up criteria of failure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.436-441
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• 2008

In this paper, we derived the Y-parameter of the recently reported Balun-BPF with a dual mode ring resonator by using the network analysis method. Using the derived Y-parameter we verified that the Balun-BPF structure satisfy the balun conditions. In order to design the Balun-BPF with arbitrary characteristics using the standard BPF design method with ease we derived the immittance slope parameters of the dual mode ring resonator with a load. The notch frequencies are also predicted. By designing with the proposed equations, simulating with a circuit simulator, fabricated and measured a Balun-BPF we confirmed the validation of the equations. The measured data shows bandwidth of 71 MHz and insertion loss of 0.92 dB at the center frequency of 2.46 GHz. It shows the phase imbalance of $174{\sim}181$ degree and the magnitude imbalance within 0.5 dB.

• Membrane Journal
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• v.15 no.4
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• pp.349-354
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• 2005

YSZ (yttria-stabilized zirconia) determined with an electrolyte that analyzed thermal stability along sintering condition and an electric characteristic. As sintering temperature increases by SEM, grain grows and it showed that pore decreases relatively. and confirmed effect by grain size. It evaluated that particle internal resistance and electric performance by resistance in an electrolyte and electricity conductivity measurement through ac impedance measurement in temperature of $800\~1000^{\circ}C$ in 2-probe method In order to recognize an electric characteristic. In dry process and wet process, density was each 6.13, 6.25 $g/cm^3$ and the relative density was each 98, 99$\%$ when sintering condition is $1400^{\circ}C$.