• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.252-252
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• 2010

AIZTO (Al-In-Sn-ZnO) thin film was deposited on glass substrate at room temperature by facing target sputtering (FTS) system. The FTS system was designed to array two targets facing each other. Two different kinds of targets were installed on FTS system. We used the ITO (In2O3 90wt%, SnO2 10wt%) target and the AZO (ZnO 98wt%, Al2O3 2wt%). AIZTO films were deposited in each of the applied power of the targets. The electrical and structural properties of the as-deposited AIZTO thin films were then examined by hall-effect measurement, and by using atomic force microscope (AFM), X-ray diffractometer (XRD), and energy dispersive x-ray spectroscopy (EDX). The optical property was measured by an UV-VIS spectrometer.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.129-136
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• 1995

In spite of the prescriptions on the reference X-ray fields given by the International Organization of Strandard(ISO) and American National Standard Institute(ANSI), the measurement of X-ray spectrum is not only time consuming but very difficult, paticularly when significant corrections have to be applied to the measured pulse-height distributions of the observed spectra. This paper describes the calculation method of ISO Narrow Series and ANSI X-ray filtered radiations by theoretical model which is modified framer's theory by target attenuation and backscatter correction. The X-ray spectra, average energies and conversion coefficients are calculated and compared with those obtained using the spectra prescribed by ISO and AMSI to assure good agreement.

• Journal of Radiation Protection and Research
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• v.2 no.1
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• pp.31-37
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• 1977

Inactivation of the glutamic acid dehydrogenase and glucose-6-phosphate dehydrogenase enzyme-molecules in the Ehrlich ascites tumor cells of the mouse were studied. The above mentioned intracellular enzymemolecules were irradiated by the X-ray radiation under the condition of 65 kV, I Amp. under the atmosphere of nitrogen gases and by $4^{\circ}C$. Thereby, irradiation doses were 580 KR/min($error:{\pm}3%$). After irradiation, the cell homogentes were prepared through liquid air techniquese. There after, the activities of the enzymes were measured with photometric method given by O. Warburg and W. Christian. The dose effect curves of the activities of the two enzymes by the X-ray irradiation showed both exponential and the inactivation doses were $6,5.10^{0}\;and\;5,0.10^{6}$ R respectively. These results showed one side that the inactivation process of the intracelluar enzymemolecules was one hit reaction after target theory, and the other side that this inactivation process could not be the primary causes of the death through X-ray irradiation of the vertebrate animals, because of the high resistance of the intracellular protein molecules against X-ray irradiation. The one hit reaction by the inactivation process of the irradiated intracellular enzymemolecules was discussed.

• Design & Manufacturing
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• v.16 no.2
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• pp.33-38
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• 2022

Currently, Korea is an aging society, and it is expected to enter a super-aging society in about 4 years. Accordingly, many X-ray technologies are being developed. In X-rays, 99% of X-rays are converted into heat energy and 1% into light energy (X-rays). 99% of the thermal energy raises the temperature of the anode and its surroundings, and the cooling system is an important factor as overheating can affect the deterioration of X-ray quality and shortened lifespan. There is a method of forced air cooling using natural convection. Therefore, in this study, when X-rays were taken 5 times, Flow analysis was performed on heat removal according to temperature rise and cooling time for the heat generated at the anode of the X-ray tube (input power 60kW, 75kW, 90kW). Based on one-shot, the most rapid temperature rise section increased by more than 57% to 0.03 seconds, A constant temperature rises from 0.03 seconds to 0.1 seconds, It is judged that the temperature rises by about 8.2% or more at one time. After one-shot cooling, the cooling drops sharply from about 60% to 0.03 seconds, It is judged that the temperature has cooled by more than 86% compared to the temperature before shooting. One-shot is cooled by more than 86% with cooling time after 0.1 seconds, As the input power of the anode increases, the cooling temperature gradually increases. Since the tungsten of the anode target inside the X-ray tube may be damaged by thermal shock caused by a rapid temperature rise, an improvement method for removing thermal energy is required when using a high-input power supply.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.433-433
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• 2016

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission. CNT yarns have demonstrated its potential as excellent field emitters. It was demonstrated that a small focal spot size was achieved by manipulating some electrical parameters, such as applied bias voltage at the mesh gate, and electrostatic focal lenses, geometrical parameters, such as axial distances of the anode, and the electrostatic focal lens from the cathode assembly, and the dimension of the opening of the electrostatic lens. Electrical-optics software was used to systematically investigate the behavior of the electron beam trajectory when the aforementioned variables were manipulated. The results of the experiment agree with the theoretical simulation results. Each variable has an individual effect on the electron beam focal spot size impinging on the target anode. An optimum condition of the parameters was obtained producing good quality of X-ray images. Also, MWCNT yarn was investigated for field emission characteristics and its contribution in the X-ray generation. The dry spinning method was used to fabricate MWCNT yarn from super MWCNTs, which was fabricated by MW-PECVD. The MWCNT yarn has a significant field emission capability in both diode and the triode X-ray generation structure compared to a MWCNT. The low-voltage-field emission of the MWCNT yarn can be attributed to the field enhancing effect of the yarn due to its shape and the contribution of the high-aspect-ratio nanotubes that protrude from the sides of the yarn. Observations of the use of filters on the development of X-ray images were also demonstrated. The amount of exposure time of the samples to the X-ray was also manipulated. The MWCNT yarn can be a good candidate for use in the low voltage field emission application of X-ray imaging.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.407-410
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• 2002

Monochromatic x-ray CT has several advantages over conventional CT, which utilizes bremsstrahlung white x-rays from an x-ray tube. There are several methods to produce such monochromatic x-rays. The most popular one is crystal diffraction monochromatization, which has been commonly used because of the fact that the energy spread is very narrow and the energy can be changed continuously. The alternative method is the use of fluorescent x-ray, which has several advantages such as large beam size and fast energy change. We have developed a parallel-beam and a fan-beam monochromatic x-ray CT, and compared some characteristics such as accuracy of CT numbers between those systems. The fan beam monochromatic x-rays were generated by irradiating target materials by incident white x-rays from a bending magnet beam line NE5 in 6.5 GeV Accumulation Ring at Tukuba. The parallel beam monochromatic x-rays were generated by using a silicon double crystal monochromator at the bending magnet beam line BL-20BM in Spring-8. A Cadmium telluride (CdTe) 256 channel array detector with 512mm sensitive width capable of operating at room temperature was used in the photon counting mode. A cylindrical phantom containing eight concentrations of gadolinium was used for the fan beam monochromatic x-ray CT system, while a phantom containing acetone, ethanol, acrylic and water was used for the parallel monochromatic x-ray CT system. The linear attenuation coefficients obtained from CT numbers of those monochromatic x-ray CT images were compared with theoretical values. They showed a good agreement within 3%. It was found that the quantitative measurement can be possible by using the fan beam monochromatic x-ray CT system as well as a parallel beam monochromatic X-ray CT system.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1062-1070
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• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.115-121
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• 2013

We fabricated thin film transistors (TFTs) using TiInZnO(TiIZO) thin films as active channel layer. The thin films of TiIZO were deposited at room temperature by RF-magnetron co-sputtering system from InZnO(IZO) and Ti targets. We examined the effects of titanium addition by X-ray diffraction, X-ray photoelectron spectroscopy and the electrical characteristics of the TFTs. The TiIZO TFTs were investigated according to the radio-frequency power applied to the Ti target. We found that the transistor on-off currents were greatly influenced by the composition of titanium addition, which suppressed the formation of oxygen vacancies, because of the stronger oxidation tendency of Ti relative to that of Zn or In. A optimized TiIZO TFT with rf power 40W of Ti target showed good performance with an on/off current ratio greater than $10^5$, a field-effect mobility of 2.09 [$cm^2/V{\cdot}s$], a threshold voltage of 2.2 [V] and a subthreshold swing of 0.492 [V/dec.].

• Progress in Medical Physics
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• v.13 no.3
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• pp.169-175
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• 2002

The purpose of this study is to verify the usefulness of X-ray simulator which uses a visible light source for further study. We developed a small experimental equipment which is composed of three main components - source, localizer and detector. Cartesian coordinate was set in 3D space, and the position of target was assumed the origin of the coordinate. The light from the source passes directly through the target, and projection image is formed on the screen, which can be taken with the digital camera. Since projection images were acquired behind the screen, they were flipped over right and left. By examining the characters of visual light source and equipments, it could be concluded that developed system was useful for experimental purpose.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.82.2-82.2
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• 2012

We present an investigation of X-ray hot gas halo in 21 early-type galaxies(ETGs) from cross-matched sample of XMM-Newton(2XMM-DR3 catalog) and SDSS DR 7(0.025 < z < 0.085 and Mr <-19.5). It has been controversial whether or not the environment affects X-ray luminosity of ETGs. In this research, we mainly considered how dense the surrounding galaxies of the target galaxy are and how isolated the target galaxy is from the nearest neighboring galaxy. It appears that the second environmental factor has more effects on X-ray luminosity (0.5-2 keV) of hot gas halo than the first one. We found that the closer a galaxy is to the nearest neighboring galaxy, the brighter it is when the galaxy is located within the neighbor galaxy's virial radius. However, when a galaxy is located outside the neighbor's virial radius, the luminosity does not show any trend. In this poster, we report preliminary results from our study.