• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2982-2989
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• 2021

One of the consequences of the 475 ℃ embrittlement of duplex stainless steels is the reduction of the resistance to localized corrosion. Therefore, the detection of this type of embrittlement before the material exhibits significant loss in toughness, and corrosion resistance is important to ensure the structural integrity of critical components under corrosion threats. In this research, conductivity measurements are performed using the alternating current potential drop (ACPD) technique with using a portable four-point probe as a nondestructive evaluation (NDE) method for detecting the embrittlement in a 2507 (UNS S32750) super duplex stainless steel (SDSS) aged at 475 ℃ from as-received condition to 300 h. The electric conductivity results were compared against two electrochemical tests namely double loop electrochemical potentiokinetic reactivation (DL-EPR) and critical pitting temperature (CPT). Mechanical tests and the microstructure characterized using scanning electron microscopy (SEM) imaging are conducted to track the progress of embrittlement. It is shown that the electric conductivity correlates with the changes in impact energy, microhardness, and CPT corrosion tests result demonstrating the feasibility of the four-point probe as a possible field-deployable method for evaluating the 475 ℃ embrittlement of 2507 SDSS.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.601-606
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• 2000

Nickel mono-silicide(NiSi) shows no increase of resistivity as the line width decreases below 0.15$\mu\textrm{m}$. Furthermore, thin silicide can be made easily and restrain the redistribution of dopants, because NiSi in created through the reaction of one nickel atom and one silicon atom. Therefore, we investigated the deposition condition of Ni films, heat treatment condition and basic properties of NiSi films which are expected to be employed for sub-0.15$\mu\textrm{m}$ class devices. The nickel silicide film was deposited on the Si wafer by using a dc-magnetron sputter, then annealed at the temperature range of $150~1000^{\circ}C$. Surface roughness of each specimen was measured by using a SPM (scanning probe microscope). Microstructure and qualitative composition analysis were executed by a TEM-EDS(transmission electron microscope-energy dispersive x-ray spectroscope). Electrical properties of the materials at each annealing temperature were measured by a four-point probe. As the results of our study, we may conclude that; 1. SPM can be employed as a non-destructive process to monitor NiSi/NiSi$_2$ transformation. 2. For annealing temperature over $800^{\circ}C$, oxygen pressure $Po_2$ should be kept below $1.5{\times}10^{-11}torr$ to avoid oxidation of residual Ni. 3. NiSi to $NiSi_2$ transformation temperature in our study was $700^{\circ}C$ from the four-point probe measurement.

• The Journal of the Acoustical Society of Korea
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• v.13 no.3
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• pp.41-50
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• 1994

We studied an inherent error be caused by a measuring acoustic intensity using probe which can measure simultaneously the three-dimensional acoustic intensity. This three-dimensional intensity probe was constructed with four microphones, proposed by Suzuki et al. . In the computer simulation, we analyzed the nearfield measurement error with arbitary direction and each of axis direction on the ideal point source and the plate sound source which have finite size. From the results, in case of point source, we obtained accurate measurement below about 1dB when the distance of measurement was about 2.5 times with the distance among microphones in this probe. And in the case of plate sound source, the nearfield measurement error was decreased as the length of one side became above 0.02m, we obtained accurate measurement below about 1dB when the length of one side is 0.2m. The nearfield measurement error of finite size sound is small to ignore. Therefore this probe is useful to measure nearfield intensity.

• The Journal of the Acoustical Society of Korea
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• v.29 no.8
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• pp.476-482
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• 2010

The ultrasonic transient fields and B-mode images of a point target which were simulated for a medical ultrasonic probe with a few defective piezo-elements were compared with those for a normal probe. The present study considered a 3.5 MHz linear array probe whose acoustic beam was formed by the 64 active elements of total 192 elements. The results showed that the maximum amplitude and -3 dB width of the acoustic fields by main-lobes decreased linearly as the defective element number increased from one to four. However, the depths of foci remained almost unchanged, and the pressure differences between main-lobes and side-lobes tended to decrease due to rise in pressures in side-lobes. Such changes in ultrasonic fields affected the B-mode images of point targets. So the artifacts were formed in the right and left side of the target, and the lateral spatial resolutions were decreased while the axial resolution was almost the same.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.929-930
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• 2007

박막재료 및 반도체의 면저항 측정에는 주로 Four Point Probe(FPP) 원리를 이용한 측정기를 사용하고 있다. FPP에 의한 측정방식은 single 및 dual configuration method가 있으며, dual configuration은 single configuration에 비해 probe spacing 변화나 시료의 가장자리 효과 등에서 측정편차가 적은 장점이 있어서 dual configuration 기술을 사용하는 추세이다. 개발된 휴대용 면저항 측정기는 dual configuration원리를 적용하여 제작되었으며, 박막재료의 면저항을 누구나 쉽고 정확하게 측정할 수 있도록 설계되었다. 또한 시료의 크기가 핀 간격에 비해 5배 이상 크면 보정계수를 거의 무시할 수 있는 장점이 있어 작은 시료라도 정확한 면저항을 측정할 수 있다. 이측정기의 측정 불확도는 지시값의 1 % 이하이고, 측정범위는 (2$\sim$2000)$\Omega/sq$이다.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.163.2-163
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• 2001

Confocal scanning microscopy (CSM) has been reported as an excellent method using the optical probe in scanning probe microscopy (SPM). Transmission or reflection confocal scanning microscopy (TCSM, RCSM) has been used in the three-dimensional reconstruction of specimen or the non-destructive measurement in vivo. The axial movement of the primary focal point having the information of specimen gives a good measurement performance with the great sensitivity. Application of the confocal theory and astigmatism to displacement measurement sensor uses the aperture as the pinhole or slit after collecting lens relating to confocal response in non-contact measurement; and astigmatic lens using four-segments detector as short-range sensor, long-range one combining the grating and rotary one hating the rotary directional grating. The aperture type can play an ...

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.303-306
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• 2001

Using THz time-domain spectroscopy (THz-TDS), the power absorption and the real conductivity of silica sand are measured terahertz frequency range. It is impossible to measure the characterization of the silica sand by simple electrical measurements using mechanical contacts, e.g., Hail effect or four-point probe measurements. However, the THz-TDS technique can measure not only electrical but also optical characterization of the sample. Also this technique can measure frequency dependent results. Especially, the real conductivity was increased according to THz frequency this is unusual material compare with metal and semiconductor materials; the measured real conductivity are not followed by the simple Drude theory.

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.54-61
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• 1996

Indium-tin oxide (ITO) films were deposited on the glass substrate by the reactive -ionized cluster beam deposition(ICBD) method. In the oxygen atmosphere, indium cluster formed through the nozzle is ionized by the electron bombardment and is accelerated to be deposited on the substrate. And tin is simultaneoulsy evaporated from the boron-nitride crucible. The chracteristics of films were examined by the X-ray photoelectron spectroscopy(XPS), glancing angle X-ray diffractrion(GXRD) and the electrical properties. were measured by 4-point-probe and Hall effect measurement system . From the XPS spectrum , it was found that indium and tin atoms combined with the oxygen to form oxide$(In_2O_3, SnO_2)$. In the case of films with high tin-concentration, the GXRD spectra show that the main $In_2O_3$ peak of (222) plane, but also sub peaks((440) peak etc.) and $SnO_2$ peaks were detected. From that results, itis concluded that the heavily dopped tin component (more than 14 at. %) disturbs to form $In_2O_3$(222) phase. Four-point-probe and Hall effect measurement show that, in the most desirable case, the transmittance of the films is more then 90% in visible range and its resistivity is $$\rho$=3.55 \times10^{-4}\Omega$cm and its mobility is $\mu$=42.8 $\textrm{cm}^2$/Vsec.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.373-373
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• 2012

We fabricated conductive zinc oxide (ZnO) thin film at low temperature by UV-enhanced atomic layer deposition. The atomic layer deposition relies on alternate pulsing of the precursor gases onto the substrate surface and subsequent chemisorption of the precursors. In this experiment, diethylzinc (DEZ) and $H_2O$ were used as precursors with UV light. The UV light was very effective to improve the conductivity of the ZnO thin film. The thickness, transparency and resistivity were investigated by ellisometry, UV-visible spectroscopy and Four-point probe.

• Journal of the Korean Vacuum Society
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• v.4 no.S1
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• pp.81-86
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• 1995

Aluminum has been deposited selectively on TiN surfaces in the presence of Si, SiO2 from Dimethyethylamine Alane(DMEAA). The film properties of the deopsited AI film were determined by various methods(SEM, Auger, UV-photospectrometer, Four point-probe, XRD). The effect of in-situ H2 plasma precleaning was studied. The effect of gap distance, pressure and temperature on the properties(crystallinity, resistance, grain size, morphology) of AI film and on the growth rates was investigated. It was found that the plasma precleaning promotes the growth rate and there exists optimum thmperature for maximum growth rate.