• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.64-64
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• 1991

The interaction of high-intensity, focused, nanosecond laser light with matter results in the production of high-temperature plasma, which in turn emits an intense pulse of x rays. The x-ray spectrum consists of strong line components of several keV photon energy and broad continuum. Such an x-ray source provides many advantages over conventional ones for many applications. Pulse nature of the x-ray emission is well-suited for studying transient phenomena and for imaging living biological specimen. Recent experiments have also shown that the laser plasma x ray may be used for x ray lithography. These studies and other applications will be discussed in detail.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.155-156
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.13-14
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• 2007

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.454-460
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• 2007

In this paper, we implemented a ray-tracing simulator with a ray-launching technique and generated the propagation path of each ray in an multiple-wall indoor environment. In this simulator, we adopted two dimension ray-tracing techniques considering the reflection and penetration were dominant propagation factor in the indoor channel. From the result, we verified that this ray-tracing simulator shows the similar pattern and delay distribution with the experiment results of the previous research.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.31-34
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• 2002

In this paper, the electric properties of amophous selenium multilayer samples has been investigated. In order to develop the hybrid flat-panel digital· X-ray image detector, we measured and analyzed their performance parameters such as the X -ray sensitivity and dark-current for a amophous selenium multilayers X-ray detector with a phosphor layer, The hybrid digital X-ray image detector can be constructed by integrating a phosphor layer (or a scintillative layer) that convert X-ray to a light on a-Se photoconduction mulilayers that convert a light to electrical signal. As results, the dielectric materials such as parylene between the phosphor layer and the top electrode may reduce the dark-current of the samples. Amorphous selenium multilayers having dielectric layer(parylene) has characteristics of low dark-current, high X-ray sensitivity. So we can acquired a enhanced signal to noise ratio. In this paper offer the method can reduce the dark-current in the hybrid X-ray detector.

• Journal of radiological science and technology
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• v.11 no.1
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• pp.33-41
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• 1988

This study was measured the radiation-induced current - X-ray dose, dose rate, X-ray quality, time, temperature, electric field characteristics and the dependence of gap length in insulating oil under of D.C. Voltage before, during and after X-ray irradiation. The obtained results can be summarized as following. 1. The radiation - induced current is more the dependence of X-ray quality (tube voltage) than quantity (tube current), the dependence of quantity is appeared at the high than low X-.ay tube voltage. 2. The dependence of dose rate is appeared at the more dose rate, and ${\triangle}\;=\;0.64{\sim}0.74$. 3. The higher temperature of insulating oil and X-ray tube voltage (X-ray quality) is increased, at the low electric field, the more radiation-induced current. 4. $G_{eq}-G_{o}(={\triangle}G)$ is increased at the low than high temperature, high than low X-ray quality. 5. The dependence of temperature is appeared before than during X-ray irradiation. 6. The RIC saturation region is appeared at the high than low insulating oil temperature during (1000 V/cm above) than before (4000 V/cm above) X-ray irradiation.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.413-413
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• 2000

In this paper, we propose a series of calibrations f3r the x-ray three dimensional imaging system. In the developed x-ray system, a three dimensional inner and outer shape of an object can be reconstructed out of two dimensional transmitted x-ray image set, which are acquired by projecting x-ray to the object from different views. To achieve this, a reconstruction algorithm which estimates and updates the three dimensional volume from x-ray images is developed. The algorithm is named as uniform and simultaneous algebraic reconstruction technique(USART) which is an iterative method estimating a 3D volume based on its projected images. In this method, it is assumed that the imaging conditions that are the relative positions between the x-ray sources, object and the image planes are blown. Practically it is not easy to know the three dimensional coordinate of the components of the system, since the x-ray is not visible and the image distortions are present due to the optical components in the system. In this paper, methods of correcting image distortions are present firstly. Then the coordinates of the x-ray systems are calibrated from the x-ray images of the grid pattern. Some experimental results on these calibrations are present and discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1182-1188
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• 2005

An x-ray PIV (Particle Image Velocimetry) technique was developed to measure quantitative information on flows inside opaque conduits and on opaque-fluid flows. At first, the developed x-ray PIV technique was applied to flow in an opaque Teflon tube. To acquire x-ray images suitable for PIV velocity field measurements, refraction-based edge enhancement mechanism was employed using detectable tracer particles. The optimal distance between with the sample and detector was experimentally determined. The resulting amassed velocity field data were in reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to blood flow in a microchannel. The flow pattern of blood was visualifed by enhancing the diffraction/interference -bas ed characteristic s of blood cells on synchrotron x-rays without any contrast agent or tracer particles. That is, the flow-pattern image of blood was achieved by optimizing the sample (blood) to detector distance and the sample thickness. Quantitative velocity field information was obtained by applying PIV algorithm to the enhanced x-ray flow images. The measured velocity field data show a typical flow structure of flow in a macro-scale channel.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.240-246
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• 2008

The x-ray transmission anode Ag-target tube was developed to apply for the thickness measurement of film in the thickness range of several tens$\sim$several hundreds ${\mu}m$ and its characteristics were evaluated. The energy distribution and dose of x-ray from Ag-target tube was investigated at the tube voltage near 10 kV, and discussed in comparition with that from W-target tube. The energy distribution and dose of x-rays passing through film were measured with various thickness of Ny and PP film. From these results, it was confirmed that our x-ray tube can be applied for the thickness measurement of film.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.2
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• pp.65-70
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• 2015

In this paper, we describe the world's first real-time ray-tracing chip architecture. Ray-tracing technology generates high-quality 3D graphics images better than current rasterization technology by providing four essential light effects: shadow, reflection, refraction and transmission. The real-time ray-tracing chip named RayChip includes a real-time ray-tracing graphics processing unit and an accelerating tree-building unit. An ARM Ltd. central processing unit (CPU) and other peripherals are also included to support all processes of 3D graphics applications. Using the accelerating tree-building unit named RayTree to minimize the CPU load, the chip uses a low-end CPU and decreases both silicon area and power consumption. The evaluation results with RayChip show appropriate performance to support real-time ray tracing in high-definition (HD) resolution, while the rendered images are scaled to full HD resolution. The chip also integrates the Linux operating system and the familiar OpenGL for Embedded Systems application programming interface for easy application development.