• Imaging Science in Dentistry
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• v.35 no.2
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• pp.87-90
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• 2005

Purpose : The purpose of this study was to investigate variability of doses with same exposure parameters and evaluate radiographic density according to the variability of doses. Materials and methods Twenty-eight MAX-GLS (Shinhung Co, Seoul, Korea), twenty-one D-60-5 (DongSeo Med, Seoul, Korea), and eleven REX-601 (Yoshida Dental MFG, Tokyo, Japan) dental x-ray machines were selected for this study Surface doses were measured under selected combinations of tube voltage, tube current, exposure time, and constant distance 42 cm from the focal spot to the surface of the Multi-O-meter (Unfors Instruments, Billdal, Sweden). Radiographic densities were measured on the films at maximum, minimum and mean surface doses of each brand of x-ray units. Results With MAX-GLS, the maximum surface doses were thirteen to fourteen times as much as the minimum surface doses. With D-60-S, the maximum surface doses were three to eight times as much as the minimum surface doses. With REX-601, the maximum surface doses were six to ten times as much as the minimum surface doses. The differences in radiographic densities among maximum, mean, and minimum doses were significant (p<0.01). Conclusion : The surface exposure doses of each x-ray machine at the same exposure parameters were different within the same manufacturer's machines.

• Journal of radiological science and technology
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• v.17 no.1
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• pp.110-114
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• 1994

• Journal of Korean Electronics
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• v.15 no.9
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• pp.38-46
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• 1995

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.251-255
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• 2007

In this paper, propagation analysis method in using 3D Ray Tracing propagation model in wireless cell planning is proposed. Through 3D Ray Tracing model, we can predict the distribution of propagation loss of the received signal. For correct and a low complex analysis, Quad Tree and Pre-Ordering and Hash Function algorithms are included in 3D Ray Tracing algorithm. And 3D Ray Tracing model is embodied in CellTREK that is developed by KT and used to plan Wibro system analysis. In CellTREK, propagation analysis is performed and that result is represented in 3D viewer. In numerical results, it is showed that the proposed scheme outperforms Modified HATA model when comparing with measurement data.

• Journal of Advanced Technology Convergence
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• v.1 no.2
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• pp.19-25
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• 2022

It is intended to evaluate the performance of the shield after manufacturing a shield with cheap and eco-friendly iron oxide and alumina instead of lead, which is a radiation shielding material. After manufacturing the shield by mixing iron oxide and alumina with gypsum, the performance is evaluated by comparing it with gypsum board and lead apron using an X-ray tube. As a result of the experiment, the shielding performance of alumina was lower than that of the gypsum board, and when 50% of alumina was contained, the shielding performance was similar to that of the gypsum board. Iron oxide became similar to the shielding performance of lead apron when it contained about 75%. A shielding material using alumina shows shielding performance similar to that of gypsum, so it is not suitable as a substitute for lead. However, since iron oxide exhibits similar shielding performance to lead, it can be used as an X-ray shielding material to replace lead in the future, so further research is needed.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.559.1-559
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• 2001

The aim of the study was to determine the direction and the rate of polymerization shrinkage of light-cured resin composite. Materials and Methods: A microfocus x-ray CT(computed tomography) instrument (SMX-255CT, Shimadzu Co., Kyoto, Japan) was used to analyze and characterize the pre-and post-gel phases. A microfocus x-ray tube was used to enable a focus dimension of 4 microns.(omitted)

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.400-403
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• 2002

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments were primarily performed in order to generate line spectra such as x-ray lasers. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbo-molecular pump, and a radiation tube with a capillary. A high-voltage condenser of 200 nF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -10.8 kV and 4.7 kA, respectively. The x-ray durations observed by a 1.6 ${\mu}$m aluminum filter were less than 30 ${\mu}$s, and we detected the aluminum characteristic x-ray intensity using a 6.8 ${\mu}$m aluminum filter. In the spectrum measurement, two sets of aluminum and titanium electrodes were employed, and we observed multi-line spectra. The line photon energies seldom varied according to changes in the condenser charging voltage and to changes in the electrode element. In the case where the titanium electrode was employed, the line number decreased with corresponding decreases in the capillary length. Compared with incoherent visible light, these rays from the capillary were diffracted and diffused greatly after passing through two slits.

• Journal of radiological science and technology
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• v.2 no.1
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• pp.85-88
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• 1979

When X-radiation passes through the human body; some is transmitted some is truly absorbed, and some is scattered. In diagnostic radiography, scattered radiation can reach the film if no protective measures are taken. This scattered ray increased density which not necessary for image formation. We studied about absorbtion, scattered ray and the way of get rid of scatter ray according to the x-ray tube kilovoltage and obtained results as follow; 1. Absorbtion ray increased proportion to KVP. 2. Scattered ray increased at high KVP and thick object. 3. Secondary radiation of the primary increased at high KVP and thick object. 4. Remove .ate of scattered ray decreased at thick object and increase at low KVP make use of 6:1 grid ratio

• Journal of the Korean Society of Radiology
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• v.4 no.3
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• pp.27-31
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• 2010

Spatial resolution is determined by the performance of x-ray optics used in the x-ray imaging system. A zone plate was designed for obtaining a high spatial resolution image at x-ray energy of 8.5keV. A spatial resolution of 80 nm was estimated by the ray tracing when an x-ray tube of tungsten targe was used instead of synchrotron radiation. The designed zone plate of outermost zone width of 40nm was successfully fabricated by the electron-beam lithography.

• Tribology and Lubricants
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• v.23 no.4
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• pp.143-148
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• 2007

The surface defects of an aluminum tube for an OPC drum have been analyzed using a scanning microscopy(SEM) and an energy dispersive X-ray analyze.(EDX). The SEM/EDX system, which may provide good information on the surface defects and their distributions, provides an optical diameter of an impurity and a chemical composition. These are strongly related on the coated film thickness and quality of an OPC drum, which is a key element of a toner cartridge for a laser printer. The experimental results show that the local deformations, scratch wear, and flaws are produce the non-uniform coating layers, which may be removed by a manufacturing process of an aluminum tube. The major parameters on the coating quality of an OPC drum are the impurities of an aluminum tube such as silicon, oxygen, calcium, carbon, sulphur, chlorine, and others. These impurities may be removed by an ingot molding, extrusion and drawing, quality control, and packing processes with a strict manufacturing technology.