• Bulletin of the Korean Chemical Society
• /
• v.35 no.12
• /
• pp.3482-3488
• /
• 2014

Matrix-induced mass bias and its effect on the accuracy of isotope ratio measurements have been examined for a quadrupole-based inductively coupled plasma-mass spectrometer (Q ICP-MS). Matrix-induced mass bias effect was directly proportional to % mass difference, and its magnitude varied for element and nebulizer flow rate. For a given element and conditions in a day, the effect was consistent. The isotope ratio of Cd106/Cd114 under $200{\mu}g\;g^{-1}$ U matrix deviated from the natural value significantly by 3.5%. When Cd 111 and Cd114 were used for the quantification of Cd with isotope dilution (ID) method, the average of differences between the calculated and measured concentrations was -0.034% for samples without matrix ($0.076{\mu}g\;g^{-1}$ to $0.21{\mu}g\;g^{-1}$ for the period of 6 months). However, the error was as large as 1.5% for samples with $200{\mu}g\;g^{-1}$ U. The error in ID caused by matrix could be larger when larger mass difference isotopes are used.

• Journal of the Korean Vacuum Society
• /
• v.13 no.1
• /
• pp.22-28
• /
• 2004

Ta films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -125 V ($V_{s}$ = -125 V) using a non-mass separated ion beam deposition system. To investigate the effect of the negative substrate bias voltage on the impurity concentration in the Ta films, secondary ion mass spectrometry (SIMS) was used to determine impurities in the Ta films. By the SIMS depth profiles with $Cs^{+}$ cluster ion beam, high intensities of O, C and Si were clearly found in the Ta film at $V_{s}$ = 0 V, whereas these impurities remarkably decreased in the Ta film at $V_{s}$ = -125 V. Furthermore, from the SIMS result with $Cs^{+}$ and $O_2^{+}$ ion beams, it was found that applying the negative substrate bias voltage could affect individual impurity contents in the Ta films during the deposition. Discussions concerning the effect of the negative substrate bias voltage on the impurity concentration of Ta films will be described in details.

• Journal of the Korean Vacuum Society
• /
• v.13 no.2
• /
• pp.79-85
• /
• 2004

Secondary ion mass spectrometry(SIMS) and glow discharge mass spectrometry(GDMS) were used to determine the impurity concentrations of hydrogen, carbon, and oxygen elements in the Cu and Ta films, and the results of SIMS and GDMS analysis were carefully considered. The Cu and Ta films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -50 V(Cu films) or -125 V(Ta films) using a non-mass separated ion beam deposition method. As a result of SIMS with Cs+ ion beam, in the case of the Cu and Ta films deposited without the substrate bias voltage, many strong peaks were observed, which is considered to be detected as a the cluster state such as CxHx, OxHx, CxOxHx. All the peaks of SIMS results could be interpreted by the combination of these dominant impurities. Moreover, it was confirmed that the quantitative results of GDMS analysis were accordant to the SIMS results.

• Journal of the Korean Vacuum Society
• /
• v.14 no.1
• /
• pp.17-23
• /
• 2005

Glow discharge mass spectrometry(GDMS) was used to determine the impurity concentrations of the deposited Cu films and the 6N Cu target. Cu films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -50 V using a non-mass separated ion beam deposition method. Since do GDMS has a little difficulty to apply to thin films because of the accompanying non-conducting substrate, we have used an aluminum foil to cover the edge of the Cu film in order to make an electrical contact of the Cu film deposited on the non-conducting substrate. As a result, the Cu film deposited at the substrate bias voltage of -50 V showed lower impurity contents than the Cu film deposited without the substrate bias voltage although both the Cu films were contaminated during the deposition. It was found that the concentration change of each impurity in the Cu films by applying the negative substrate bias voltage is related to the difference in their ionization potentials. The purification effect by applying the negative substrate bias voltage might result from the following reasons: 1) Penning ionization and an ionization mechanism proposed in the present study, 2) difference in the kinetic energy of accelerated Cu+ ions toward the substrate with/without the negative substrate bias voltage.

• Korean journal of communication and information
• /
• v.48
• /
• pp.191-210
• /
• 2009

In this study, we examined the influence of news frame and involvement on risk perception. Based on individuals' optimistic bias in risk judgement and the third-person effect theory, we developed research hypotheses. An experiment was conducted in which 243 undergraduate and graduate students participated. Results indicated that societal level risk judgements were relatively invariant across experimental conditions but personal level risk judgements were influenced by the news frame and individuals' involvement in irradiated food. Based on the results, we provide explanations concerning when and how optimistic bias takes place in each experimental condition.

• Journal of the Korean Vacuum Society
• /
• v.12 no.S1
• /
• pp.36-39
• /
• 2003

Field-domain dynamics and current self-oscillations are theoretically studied in quantum-well (QW) negative-effective-mass (NEM) $p^{+}pp^{+}$ diodes when the electric field is applied along the direction of the well. The origin of current self-oscillations is the formation and traveling of electric-field domains in the p-base. We have accurately considered the scattering contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon. It's indicated that, both the applied bias and the doping concentration largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM $p^{+}pp^{+}$ diode with a submicrometer p-base. The complicated field-domain dynamics is presented with the applied bias as the controlling parameter.

• Korean Journal of Occupational Health Nursing
• /
• v.25 no.3
• /
• pp.199-207
• /
• 2016

Purpose: The purpose of this study was to identify the obesity stress, weight bias and health care on Body Mass Index (BMI) in soldiers of non-combat area and to provide data for improving the quality of their life. Methods: This research involved 165 soldiers working in non-combat area. Data collection was conducted from November 1 to 20, 2015. Statistical analysis of the collected data were t-test and ANOVA, $Scheff{\acute{e}}$ method post hoc analysis, Pearson's correlation coefficients, and multiple liner regression using IBM SPSS 22.0. Results: The mean score of obesity stress was moderate ($19.05{\pm}5.28$). The mean score of weight bias was 69.03 and health care was 2.41 points. There are a positive correlation between obesity stress and BMI (r=.19, p<.05). Weight bias (r=-.19, p<.01) and health care (r=-.26, p<.01) among the subjects had negative correlations with BMI. In a multiple liner regression, obesity stress (${\beta}=.18$, p<.05), health care (${\beta}=-.18$, p<.05) were associated with BMI. Conclusion: Based on the findings that obesity stress and health care influence BMI, there is a need to control stress and to properly set proper guidelines on health care for soldiers.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.5
• /
• pp.197-199
• /
• 2011

In this paper, the bottom-gate thin-film transistors (TFTs) were fabricated with an amorphous/microcrystalline Si double layer (DL) as an active layer and the variations of the electrical characteristics were investigated according to the DC bias stresses. Since the fabrication process of DL TFTs was identical to that of the conventional amorphous Si (a-Si) TFTs, it creates no additional manufacturing cost. Moreover, the amorphous/microcrystalline Si DL could possibly improve stability and mass production efficiency. Although the field effect mobility of the typical DL TFTs is similar to that of a-Si TFTs, the DL TFTs had a higher reliability with respect to the direct current (DC) bias stresses.

• Applied Science and Convergence Technology
• /
• v.23 no.3
• /
• pp.145-150
• /
• 2014

MgO thin films were deposited by internal ICP-assisted reactive-magnetron sputtering with bipolar pulse bias on a substrate to suppress random arcs. Mg is reactively sputtered by a bipolar pulsed DC power of 100 kHz into ICP generated by a dielectrically shielded internal antenna. At a mass flow ratio of $Ar/O_2$ = 10 : 2 and an ICP/sputter power ratio of 1 : 1, optimal film properties were obtained (a powder-like crystal orientation distribution and a RMS surface roughness of approximately 0.42 nm). A bipolar pulse substrate bias at a proper frequency (~a few kHz) prevented random arc events. The crystalline preferred orientations varied between the (111), (200) and (220) orientations. By optimizing the plasma conditions, films having similar bulk crystallinity characteristics (JCPDS data) were successfully obtained.

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.1
• /
• pp.32.2-32.2
• /
• 2013

We examine large-scale environmental effects on the formation and the mass growth of dark matter halos. To facilitate this, we constructed dark matter halo merger trees from a cosmological N-body simulation, which enabled us to trace the merger information and the assembly history of individual halos. In fact, since the massive halos are more likely to be distributed in denser regions than in less dense regions (Mo & White, 1996), the large-scale environment dependence of the properties of halos can be partly originated from the halo mass effect. In order to avoid such contamination, caused by the mass dependence of halo properties, we carefully measured the local overdensity as the indicator of large-scale environment, which was calculated to be as independent of halo mass as possible. Small halos (${\sim}10^{11-12}M_{\odot}$), which usually host isolated single galaxies, show a notable difference on the formation time of galaxies depending on their large-scale environments, which reconfirms halo assembly bias (Gao & White, 2007). Furthermore, we investigate how this environmental effect on small halos is correlated with the mass assembly history of galaxies by using our semi-analytic model. We found that assembly bias in small halos does not have significant effects on the formation time or on the star formation history of galaxies residing in those halos except for the individual stellar mass of galaxies at z = 0. On average, isolated galaxies in high-density regions tend to be slightly more massive than those in low-density regions. Although the observational data from the current galaxy surveys is not yet sufficient for testing this prediction, future galaxy surveys will be able to explore these small galaxies more thoroughly.