투명전도산화막인 Ga-도핑된 ZnO (GZO) 박막을 RF 마그네트론 스퍼터링 증착법을 이용하여 증착하고 전기적, 광학적 특성을 연구하였다. 증착변수로 공정압력에 변수를 주었으며 공정 압력 변화에 따라 전기적 특성과 광학적 특성이 달라짐을 확인할 수 있었다. 모든 박막은 공정압력에 상관없이 c-축(002) 방향성을 나타냈다. 증착된 GZO 박막의 전기저항성은 $8.68{\times}10^{-3}{\Omega}{\cdot}cm\sim2.18{\times}10^{-3}{\Omega}{\cdot}cm$이었고, 모든 가시광 영역에서 90% 이상의 평균 투과율을 보였다. 공정압력에 따라 상온에서 증착된 GZO 박막은 우수한 낮은 저항성과 높은 투과율을 나타내었고, 평판디스플레이와 태양전지의 투명전극으로 응용되기에 적합한 특성을 지닌 것을 확인 할 수 있었다. Ga-doped ZnO (GZO) thin films for application as transparent conducting oxide film were deposited on the glass substrate by using rf-magnetron sputtering system. The effects of working pressure on electrical and optical characteristics of GZO films were investigated. Regardless of the working pressure, all films were oriented along with the c-axis, perpendicular to the substrate. The electrical resistivity was about $8.68{\times}10^{-3}{\Omega}{\cdot}cm\sim2.18{\times}10^{-3}{\Omega}{\cdot}cm$ and the average transmittance of all films including substrates was over 90% in the visible range. The good transparents and conducting properties were obtained due to controle the working pressure. The obtained results have acceptable for application as transparent conductive electrodes in LCDs and solar cells.
We have developed the first smoothed particle hydrodynamics code for investigating X-pinch plasmas driven by pulsed power generators. To achieve the required code performance, we incorporated and discussed appropriate physics models capable of simulating the X-pinch phenomenon across various domains, encompassing equation of state, plasma transport, and radiation effects. The simulations were conducted in full three dimensions using our newly developed code, and we have compared and evaluated the results with experimental data obtained from the X-pinch device at Seoul National University. As a result, our simulations effectively captured the implosion behavior of X-pinch plasma, faithfully reproducing the four-step evolution process commonly observed in typical X-pinch configurations. Furthermore, it provided comprehensive spatiotemporal data on various plasma parameters, including density, temperature, velocity field, and radiated power. Notably, the electron temperature and density at the hot spot well agree with the experimental measurements, validating the accuracy and reliability of the developed simulation code. Additionally, the radiation data exhibited significantly improved accuracy compared to previous simulation results, confirming the effectiveness of the proposed radiation model, and it provides valuable insights into the X-pinch hot spot formation.
Background: In this study, the optimal effect-site concentration of remifentanil for blunting hemodynamic responses to endotracheal intubation during total intravenous anesthesia using propofol were evaluated. Methods: 137 ASA class I and II patients, aged 18�� 60 years, were randomly allocated to one of six groups according to the effect-site concentration of remifentanil. Remifentanil was then infused at a target effect-site concentration of 0, 1, 2, 3, 4 or 6 ng/ml in groups R0, R1, R2, R3, R4 and R6, respectively. Anesthesia was induced with propofol infusion at a target effect-site concentration of 4μg/ml endotracheal intubation was performed 5 minutes after remifentanil administration. Blood pressure (BP), heart rate (HR) and cardiac index (CI) were recorded at the baseline and then every 30 seconds until 3 minutes after intubation. Results: BP and HR in groups R0, R1 and R2 increased significantly after intubation when compared with the baseline values. The CI in group R0 also increased significantly after intubation when compared with the baseline values. Incidences of hypertension and hypotension were 50% and 5% in R0, 32% and 14% in R1, 18% and 32% in R2, 10% and 48% in R3, 8% and 54% in R4, and 0% and 81% in R6. There were also 2 cases in which the mean blood pressure was less than 50 mmHg in group R6. Conclusions: We suggest that the optimal target effect-site concentrations of remifentanil for blunting hemodynamic responses to endotracheal intubation are 3 or 4 ng/ml during total intravenous anesthesia using propofol at an effect-site concentration of 4μg/ml. (Korean J Anesthesiol 2008; 54: 30∼6)
The audio vision system was developed for visually impaired people and usability was verified. In this study ten normal volunteers were included in the subject group and their mean age was 28.8 years old. Male and female ratio was 7:3. The usability of audio vision system was verified by as follows. First, volunteers learned distance of obstacles and up-down discrimination. After learning of audio vision system, indoor and outdoor walking examination was performed. The test was scored by ability of up-down and lateral discrimination, distance recognition and walking without collision. Each parameter was scored by 1 to 5. The results were 93.5 +- SD(ranges, 86 to 100) of 100. In this study, we could convert visual information to auditory information by audio-vision system and verified possibility of applying to daily life for visually impaired people.
This paper investigates wire X-pinch (WXP) evolutions by the Eulerian resistive magneto-hydrodynamic code, STHENO, on 2D/3D geometry. A single-fluid two-temperature model is applied to pinch plasmas in local thermal equilibrium. The equation of state based on the Thomas–Fermi model is used to determine the ionization degree of the plasma. Electron internal energy is determined by the local density, temperature, and ionization potential with the average ion charge state. Lee–More–Desjarlais transport models are employed to obtain the thermal conductivities and resistivity for a non-ideal plasma. The radiation loss rate is calculated by the Bremsstrahlung and recombination emissivity within the ionization balance. The crossing point, which is the central part of the X-pinch, is assumed to be an axisymmetric configuration on a small computational domain in the RZ plane. The 2D simulation demonstrates that the micrometer size plasma column is elongated axially with the onset of the neck cascading structure. The radiation power is calculated and compared with the measured x-ray power from a modular X-pinch device (120-kA in 650-ns) at Seoul National University. The time evolution of the radiation power reproduces the trend of the measured x ray. 3D analyses are performed for the aluminum WXP configurations by varying wire numbers and cross-angles. The relation between the radiation performance and the numbers of wires reveals that the current density, rather than the line density, determines the central pinching condition. In addition, the multiple plasma instabilities (m = 0) near the central regions are found to degrade the radiation performance on the small cross-angle WXP.
We have grown GaN layers with in-situ SiN mask by metal organic chemical vapor deposition (MOCVD) and study the physical properties of the GaN layer. We have also investigate the effect of the SiN mask on its optical property. By inserting a SiN mask, (102) the full width at half maximum (FWHM) decreased from 480 arcsec to 409 arcsec and threading dislocation (TD) density decreased from $3.21\times10^9\;cm^{-2}\;to\;9.7\times10^8\;cm^{-2}$. The PL intensity of GaN with SiN mask improved 2 times to that without SiN mask. We have thus shown that the SiN mask improved significantly the physical and optical properties of the GaN layer.
Investigation of improving the properties of UV detector which uses the wide bandgap of ZnO are under active progress. The present study focused on the design and fabrication of i-ZnO/p-inversion $layer/n^--Si$ Epi. which is characterized with very thin p-type inversion layer for UV detectors. The i-ZnO thin film for achieving p-inversion layer which was grown by RF sputtering at $450^{\circ}C$ and then annealed at $400^{\circ}C$ in $O_2$ gas for 20 min shows good intrinsic properties. High (0002) peak intensity of the i-ZnO film is shown on XRD spectrum and it is confirmed by XPS analysis that the ratio of Zn : O of the i-ZnO film is nearly 1 : 1. Measurement shows high transmission of 79.5 % in UV range (< 400 nm) for the i-ZnO film. Measurement of $V_r-I_{ph}$ shows high UV photo-current of 1.2 mA under the reverse bias of 30 V.
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