• Journal of the Korean institute of surface engineering
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• v.27 no.5
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• pp.253-260
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• 1994

Ta-N films were reactively sputter deposited by dc magnetron sputtering from a Ta target with a various Ar-N, gas ratio. Electrical resistivity of pure Ta film was 150$\mu$$\Omega$cm and decreased initially with nitrogen addition, and then increased to a value of 220$\mu$$\Omega$-cm~260$\mu$$\Omega$-cm at 9%~23% nitrogen partial flow. Rutherford backscattering spectrometry(RBS) and Auger electron spectroscopy (AES) analysis show that nitrogen content in the film is increased with the nitrogen partial flow. The film contains 58at.% nitrogen at 36% nitrogen partial flow. Both the phase and the microstructure of the as-deposisted films were investigated by x-ray diffractometry(XRD) adn transmission electron microscopy (TEM) at various nitrogen content. The phase of pure Ta film is identified as $\beta$-Ta with a 200$\AA$~300$\AA$ grain size. The phase of Ta film is changed to bcc-Ta as small amount of nitrogen is added. Crystalline Ta2N film was deposited at 24at.% nitrogen content. Amorphous phase is formed over a range of nitrogen content from about 33at.% to 35at.% while crystalline fcc-TaN is observed to form at 39at.%~48at.% nitrogen content.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.2
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• pp.101-111
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• 2010

Objectives : The purpose of this study was to investigate differences between traffic accident and non-traffic accident patients in the early stage, by analysis of the heart rate variability(HRV) and visual analogue scale(VAS). Methods : This study carried out on 38 patients who complained of nuchal or lower back pain. They have received hospital treatment in Dae-Jeon Univ. Cheonan Oriental Hospital. In the TA(Traffic accident) group, the pain caused by TA and in non-TA group, the pain caused by other reasons. We measured HRV and VAS twice(pre-treatment(Tx.) and post-Tx.). Then we analyzed the data. Results : As time goes by, patients who complained of pain showed the inclination to improve ability to balance autonomic nerve system. And fatigue and pain were improved. But they showed the inclination to increase stress index. At pre-Tx., TA group had more stress and worse ability to balance autonomic nerve system, but showed lower fatigue index than non-TA group. But, as time goes by, in TA group the fatigue and autonomic balance got worse. At pre-Tx., non-TA group complained of more severe pain than TA group, but at post-Tx., TA group complained of more severe pain than non-TA group. In other words, in TA group, the decreasing rate of pain was lower than non-TA group. Conclusions : Results from this investigation showed that TA have a negative effect on stress index, ability to balance autonomic nerve system, fatigue index and decreasing rate of pain. These results are expected to consider characteristics of patients who complained of pain caused by TA.

• Journal of the Korean institute of surface engineering
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• v.25 no.3
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• pp.126-132
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• 1992

Recent VLSI requires materials with high dielectric constant in order to reduce their storage capacitor areas. Thin TaOx film was formed from Ta(OCH3)5 by photo-CVD method at a low temperature. The result shows that the film obtained by photo-CVD method is this study has good step coverage, high dielectric constant (20-25) and low leakage current. The high strong peaks from Ta(4f), Ta(4d), and O(ls) levels were observed by XPS analysis. From the diffraction pattern and TEM prcture analysis, the TaOx thin film was observed to be amorphous. This kind of the deposition method could be considered to be a very promising method applied to VLSI.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.24.2-24.2
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• 2008

We have examined the relative contributions of representative space weather proxies (geomagnetic aa index) to global warming (Global temperature anomaly) and compared them with that of green house effect characterized CO2 content from 1868 to 2005. For this we used Hadcrut3 temperature anomaly (Ta) data, aa index taken at two anti-podal subauroral stations (Canberra Australia and hartland England), and the CO2 data come from historical ice core records. From the comparison between Ta and aa index, we found several interesting results: (1) the linear correlation coefficient between two parameters increases until 1990 and then decreases rapidly, and (2) the scattered plots between two parameters shows different patterns before and after 1990. A partial correlation of Ta and two quantities (aa, CO2) also shows that the geomagnetic effect (aa index) is dominant until about 1990 and the CO2 effect becomes much more important after then. These results imply that the green house effect become very important since at least 1990. For a further analysis, we simply assume that Ta (total) = Ta (aa) + Ta (CO2) and made a linear regression between Ta and aa index from 1868 to 1990. A linear model is then made from the linear regression between energy consumption (a proxy of CO2 effect) and Ta (total) - Ta (aa) since 1990. This linear model makes it possible to predict the temperature anomaly in 2030, about 1 degree higher than the present temperature, which is much larger than in the previous century.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.79.3-80
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• 2016

We have investigated the correlation analysis between global temperature anomaly and two main factors: geomagnetic activity (aa index) of Earth external factor and CO2 of Earth internal factor. For this, we used NOAA Global Surface Temperature anomaly (Ta) data from 1868 to 2015. The aa index indicates the geomagnetic activity measured at two anti-podal subauroral stations (Canberra Australia and Hartland England) and the CO2 data come from historical ice core records and NOAA/ESRL data. From the comparison between (Ta) and aa index, we found several interesting things, First, the linear correlation coefficient between two parameters increases until 1985 and then decreases rapidly. Second, the scattered plot between two parameters shows a boundary of the correlation tendency (positive and negative correlation) near 1985. A partial correlation of (Ta) and two main factors (aa index, CO2) also shows that the geomagnetic effect (aa index) is dominant until about 1985 and the CO2 effect becomes much more important after then. These results indicate that the CO2 effect become very an important factor since at least 1985. For a further analysis, we simply assume that Ta = Ta(aa)+Ta(CO2) and made a linear regression between (Ta) and aa index from 1868 to 2015. A linear model is then made from the linear regression between energy consumption (a proxy of CO2 effect) and Ta-Ta(aa) since 1985. Our results will be discussed in view of the prediction of global warming.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.597-603
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• 2016

Tantalum carbide, which is one of the ultra-high temperature ceramics, was deposited on graphite by low pressure chemical vapor deposition from a $TaCl_5-C_3H_6-Ar-H_2$ mixture. To maintain a constant $TaCl_5/C_3H_6$ ratio during the deposition process, $TaCl_5$ powders were continuously fed into the sublimation chamber using a screw-driven feeder. Sublimation behavior of $TaCl_5$ powder was measured by thermogravimetric analysis. TaC coatings have various phases such as $Ta+{\alpha}-Ta_2C$, ${\alpha}-Ta_2C+TaC_{1-x}$, and $TaC_{1-x}$ depending on the powder feeding methods, the $C_3H_6/TaCl_5$ ratio, and the deposition temperatures. Near-stoichiometric TaC was obtained by optimizing the deposition parameters. Phase compositions were analyzed by XRD, XPS, and Raman analysis.

• Korean Journal of Materials Research
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• v.28 no.2
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• pp.75-81
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• 2018

An ultra-high temperature ceramic, tantalum carbide, has received much attention for its favorable characteristics: a superior melting point and chemical compatibility with carbon and other carbides. One drawback is the high temperature erosion of carbon/carbon (C/C) composites. To address this drawback, we deposited TaC on C/C with silicon carbide as an intermediate layer. Prior to the TaC deposition, the $TaCl_5-C_3H_6-H_2$ system was thermodynamically analyzed with FactSage 6.2 and compared with the $TaCl_5-CH_4-H_2$ system. The results confirmed that the $TaCl_5-C_3H_6-H_2$ system had a more realistic cost and deposition efficiency than $TaCl_5-CH_4-H_2$. A dense and uniform TaC layer was successfully deposited under conditions of Ta/C = 0.5, $1200^{\circ}C$ and 100 torr. This study verified that the thermodynamic analysis is appropriate as a guide and prerequisite for carbide deposition.

• Journal of Korean Academy of Nursing
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• v.27 no.3
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• pp.520-530
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• 1997

Antineoplastic agents may exhibit effects not only in patients therapeutically exposed, but also in health workers who prepare and administer these drugs. This study was done to clarify whether nurses who handle anticancer drugs show signs of drug absorption. The experimental group was 14 nurses handling anticancer drugs at three medical wards of a hospital in J city ; the control group was 12 psychiatric nurses at the same hospital. The test materials were the nurses' 24hr urine specimens, which were concentrated by XAD-2 column chromatograpy. Tester strains were TA98(±S9mix), TA100(±S9 mix), TA1535(±S9 mix) and TA1537(±S9 mix) : the salmonella mammalian microsomal test (Ames test) was used for the urinary mutagenicity assay. The results are summarized as follow : 1. In qualitative analysis of the results, both experimental group and control group showed 15.4% urine toxicity. 2. The experimental group revealed significantly higher urinary mutagenicity both in the activation method test and non-activation method test of the tester strains TA98, TA100 and TA1535. In the case of TA1537, the two groups showed no difference in the non-activation method test, but the activation method revealed a difference. 3. In urinary mutagenicity of the experimental group by ward career, there was a significant difference between the group with more than 20 months experience and the group with less than 20 months on the tester strains TA98, TA100, and TA1537. No Significant difference was found between two groups by the tester strain TA1535.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.361-366
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• 2004

The interface stability of Ta-Mo alloy film on SiO$_2$ was investigated. Ta-Mo alloy films were formed by co-sputtering method, and the alloy composition was varied by controlling Ta and Mo sputtering power, When the atomic composition of Ta was about 91％, the measured work function was 4.24 eV that is suitable for NMOS gate. To identify interface stability between Ta-Mo alloy film and SiO$_2$, C-V and XRD measurements were performed on the samples annealed with rapid thermal processor between $600^{\circ}C$ and 90$0^{\circ}C$. Even after 90$0^{\circ}C$ rapid thermal annealing, excellent interface stability and electrical properties were observed. Also, thermodynamic analysis was studied to compare with experimental results.

• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.5-8
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• 2003

In this study, as Cu diffusion barrier, tantalum nitrides were successfully deposited on Si(100) substrate and $SiO_2$ by plasma assisted atomic layer deposition(PAALD) and thermal ALD, using pentakis (ethylmethlyamino) tantalum (PEMAT) and NH$_3$ as precursors. The TaN films were deposited at $250^{\circ}C$ by both method. The growth rates of TaN films were 0.8${\AA}$/cycle for PAALD and 0.75${\AA}$/cycle for thermal ALD. TaN films by PAALD showed good surface morphology and excellent step coverage for the trench with an aspect ratio of h/w -1.8:0.12 mm but TaN films by thermal ALD showed bad step coverage for the same trench. The density for PAALD TaN was 11g/cmand one for thermal ALD TaN was 8.3g/$cm^3$. TaN films had 3 atomic % carbon impurity and 4 atomic % oxygen impurity for PAALD and 12 atomic % carbon impurity and 9 atomic % oxygen impurity for thermal ALD. The barrier failure for Cu(200 nm)/TaN(10 nm)/$SiO_2$(85 nm)/ Si structure was shown at temperature above $700^{\circ}C$ by XRD, Cu etch pit analysis.