• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.90-94
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• 1997

The joints between the superconducting wires are inevitably needed from the requirement of a high magnetic stability with respect to time in the superconducting MRI magnet. In this study, a new superconducting joint using Cu/Nb-Ti sleeve has been tried on the MRI type Nb-Ti superconducting wires. The transformer induction type apparatus was made and applied to measure the joint resistance. A very low joint resistance of 10\ulcorner $\Omega$ could be successfully obtained from this joint method. It was confirmed that the initial rapid current decay occurs before the very stable current decay due to only superconducting joint. Some unstable part in the joint like exposed filaments causes the initial induced current to lower and influence on the increase of the joint resistance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.692-695
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• 1999

This paper presents annealing characteristics of CrN thin-film strain gauges, which were deposited on glass by DC reactive magnetron sputtering in an argon-nitrogen atmosphere)Ar-(5-~25%)$N_2$. The physical and electrical characteristics of these films investigated with the thickness range 3500$\AA$ of CrN thin films, annealing temperature (100~30$0^{\circ}C$) and annealing time (24-72hr) . The optimized condition of CrN thin-film strain gauges were thickness range of 3500$\AA$ and annealing condition(30$0^{\circ}C$ , 48hr) in Ar-10%$N_2$ deposition atmosphere. Under optimum conditions, the CrN thin-films for strain gauge is obtained a high resistivity, $\rho$=1147.65$\Omega$cm a low temperature coefficient of 11.17. And change in resistance after annealing for the CrN thin film were quitely linear and stable.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.234-237
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• 2002

The cobalt silicide was formed OH POly-Si/SiO$_2$/Si Substrates by the E-beam evaporation of Co metal and rapid thermal annealing method for the application of heating actuators. The most stable CoSi$_2$crystal was obtained at temperature of above $700^{\circ}C$ for 20 sec in $N_2$ambient. From the SEM observation, the thickness and diameter of the heating elements were about $1{\mu}{\textrm}{m}$ and $50{\mu}{\textrm}{m}$, respectively. Temperature resistance coefficient of heating elements was found to be about 0.0014($1/^{\circ}C$) with $30~35\Omega$ of resistance.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.5-32
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• 2000

MRAM, High performance MRAM using MTJS demostrated, fully integrated MTJ MRAM with CMOS circuits, write time ~2.3 nsec; read time ~3 nsec, Thermally stable up to ~350 C, Switching field distibution controlled by size & shape. Magnetic Tunnel Junction Properties, Magnetoresistance: ~50% at room temperature, enhanced by thermal treatment, Negative and Positive MR by interface modification, Spin Polarization: >55% at 0.25K, Insensitive ot FM composition, Resistance $\times$ Area product, ranging from ~20 to 10$^{9}$ $\Omega$(${\mu}{\textrm}{m}$)$^{2}$, Spin valve transistor, Tunnel injected spin polarization for "hot" electrons, Decrease of MTJMR at high bias originates from anode.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2004년도 추계학술발표대회 논문집
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• pp.240-246
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• 2004

For the prediction on the onset of oblique shock wave-induced vortex breakdown, computational studies on the Oblique Shock wave/Vortex Interaction (OSVI) are conducted and compared with both experimental results and analytic model. A Shock-stable numerical scheme, the Roe scheme with Mach number-based function (RoeM), and a two-equation eddy viscosity-transport approach are used for three-dimensional turbulent flow computations. The computational configuration is identical to available experiment, and we attempt to ascertain the effect of parameters such as a vertex strength, streamwise velocity deficit, and shock strength at a freestream Mach number of 2.49. Numerical simulations using the ${\kappa}-{\omega}SST$ turbulence model and suitably modeled vortex profiles are able to accurately reproduce many fine features through a direct comparison with experimental observations. The present computational approach to determine the criterion on the onset of oblique shock wave-induced vortex breakdown is found to be in good agreement with both the experimental result and the analytic prediction.

• 한국전기전자재료학회논문지
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• 제14권11호
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• pp.885-891
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• 2001

Ring/dot-type step-down piezoelectric transformer was manufactured by using Pb[(Mn$\sub$1/3/Sb$\sub$2/3)$\sub$0.05/Zr$\sub$0.475/Ti$\sub$0.475/]O$_3$ ceramics, which have excellent high-power piezoelectric properties. The characteristics of step-down piezoelectric transformer as a function of load resistance at output terminal was examined. Voltage gain was greatly dependent on drive frequency and load resistance, and showed maximum voltage gain at the resonance frequency. The output voltage was linearly increased as the input voltage increased. Voltage gain of the step-down piezoelectric transformer with respect to input voltage was very stable when the load resistance was in the range of 50-500 $\Omega$ .

• 센서학회지
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• 제6권1호
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• pp.49-55
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• 1997

스퍼터링 방법에 의하여 유리 기판위에 ZnO 박막을 형성하여 증착막의 전기, 광학적 특성을 조사하였다. 실온에서 180 W의 고주파 전력과 $1{\times}10^{-3}$ Torr의 스퍼터링 압력일 때 증착된 박막에서 가장 강한 c축 배향성과 가장 낮은 저항률 값($1{\times}10^{-4}{\Omega}{\cdot}cm$)을 나타내었고, 이 때의 캐리어 농도 및 홀 이동도는 각각 $6.27{\times}10^{20}cm^{-3}$와 $22.04cm^{2}/V{\cdot}s$이었다. 증착된 ZnO 박막의 가시광 투과율은 90% 이상을 나타내었으며 330 nm 이하의 자외선 영역과 830 nm 이상의 적외선 영역에서는 뛰어난 광 차단 효과를 나타내었다. 또한 증착된 박막을 수소 분위기에서 열처리함으로써 저항률이 감소하였고, 안정된 박막을 얻을 수 있었다.

• 마이크로전자및패키징학회지
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• 제9권2호
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• pp.49-54
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• 2002

Poly-Si/$SiO_2$/Si 하부기판구조 위에 Co 금속을 E-beam evaporation 방식으로 증착하고 급속 열처리 방식을 통해 프린터 heater용 코발트실리사이드 박막을 형성하였다. 급속열처리 온도 (600~$900^{\circ}C$)와 시간 (20~40초)을 변수로 하여 코발트실리사이드의 결정상 및 성분분포를 조사하였다. 또한 제작된 박막의 면저항과 결정특성 분석을 통해 고온에서의 열적 안정성을 확인하였다. $800^{\circ}C$ 온도에서 20초간 급속열처리한 경우 면저항이 약 $0.8 \Omega /\Box$ 인 안정한 $CoSi_2$ 결정상의 코발트실리사이드 박막이 얻어졌다. 그러나 $700^{\circ}C$ 이하의 온도에서는 결정상의 변화에 따라 코발트실리사이드 박막의 면저항이 급격히 증가하였다. 코발트실리사이드 박막의 온도저항계수는 약 $0.0014/^{\circ}C$ 값을 나타내었으며, 프린터 발열체로 응용가능함을 확인 할 수 있었다.

• 전기학회논문지
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• 제67권3호
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• pp.413-418
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• 2018

In this paper, we describe the development of a non-enzymatic glucose sensor based on copper nanocubes(Cu NCs) electroplated laser induced graphene(LIG) electrodes which can detect a certain range of glucose concentrations. $CO_2$ laser equipment was used to form LIG electrodes on the PI film. This fabrication method allows easy control of the LIG electrode size and shape. The Cu NCs were electrochemically deposited on the LIG electrodes to improve electron transfer rates and thus enhancing electrocatalytic reaction with glucose. The average sheet resistances before and after electroplating were $15.6{\Omega}/{\Box}$ and $19.6{\Omega}/{\Box}$, respectively, which confirmed that copper nanocubes were formed on the laser induced graphene electrodes. The prepared electrode was used to measure the current according to glucose concentration using an electrochemical method. The LIG electrodes with Cu NCs demonstrated a high degree of sensitivity ($1643.31{\mu}A/mM{\cdot}cm^2$), good stability with a linear response to glucose ranging from 0.05 mM to 1 mM concentration, and a limit of detection of 0.05 mM. In order to verify that these electrodes can be used as flexible devices, the electrodes were bent to $30^{\circ}$, $90^{\circ}$, and $180^{\circ}$ and cyclic voltammetry measurements were taken while the electrodes were bent. The measured data showed that the peak voltage was almost constant at 0.42 V and the signal was stable even in the flexed condition. Therefore, it is concluded that these electrodes can be used in flexible sensors for detecting glucose in the physiological sample like saliva, tear or sweat.

• Journal of Ecology and Environment
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• 제36권4호
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• pp.223-233
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• 2013

Acid deposition is one of the most serious environmental problems in ecosystems. The present study surveyed the effects of simulated acid rain on leaf litter mass loss and microbial community in the decomposing leaf litter of Sorbus anifolia in a microcosm at $23^{\circ}C$ and 40% humidity. Microbial biomass was measured by substrate-induced respiration (SIR) and phospholipid fatty acids (PLFAs), and the microbial community structures were determined by composition of PLFAs at each interval of decomposition in litter sample and at each pH treatment. The microbial biomass showed peaks at mid-stage of decomposition, decreasing at the late stage. The leaf litter mass loss of S. anifolia decreased with decreasing pH during early and mid-decomposition stages; however the mass loss becomes similar between pH treatments at late-decomposition stage. The acidification remarkably lowers the microbial biomass of bacteria and fungi; however, microbial diversity was unchanged between pH treatments at each stage of litter decomposition. With changes of decomposition stage and pH treatment there were considerable differences in replacement and compensation of microbial species. Fungi/bacteria ratio was considerably changed by pH treatment. The PLFA profile showed significantly larger fungi/bacteria ratio at pH 5 than pH 3 at the early stage of decomposition, and the difference becomes smaller at the later decomposition stage. At low pH, pH 3 and pH 4, the fungi/bacteria ratios were stable according to the litter decomposition stages. Simulated acid rain caused decreases of 10Me17:0, 16:1${\omega}$7c, 18:1${\omega}$7, 15:0, but increase of 24:0. In addition, litter mass loss showed significant positive correlation with microbial biomass measured by SIR and PLFA on the decomposing leaf litter.