• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.198-203
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• 2013

The purpose of this study is to investigate the scattered dose of X-ray at a distance of 30cm from the area to be examined when X-ray field is the most optimized and maximized when X-ray is performed on hand, skull and abdomen. As a result of scattered dose of X-ray on hand, skull and abdomen, first, when X-ray field was the most optimized upon adult X-ray examination, it was $0.08{\mu}Sv$, $4.39{\mu}Sv$ and $5.56{\mu}Sv$, respectively. When x-ray field was maximized, it was $0.58{\mu}Sv$, $33.47{\mu}Sv$ and $35.93{\mu}Sv$, respectively. Second, when X-ray field was the most optimized upon pediatric X-ray examination, it was $0.40{\mu}Sv$, $14.51{\mu}Sv$ and $18.86{\mu}Sv$, respectively. When x-ray field was maximized, it was $2.78{\mu}Sv$, $107.40{\mu}Sv$ and $117.52{\mu}Sv$, respectively(P<0.001). As a result, when the size of X-ray field was decreased down to be necessary and optimal upon X-ray examination, emission of scattered X-ray around specimen is reduced approximately 6-7 times as much as that when it was maximized.

• 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 Environmental Health Sciences
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• v.21 no.1
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• pp.78-85
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• 1995

Ornithine decarboxylase(ODC) is an indicate enzyme in carcinogenesis. We divided Sprague Dawley rats into six groups: control, electric field exposure, X-ray only irradiation, X-ray irradiation with electric field exposure group, Sr-90 injected group and Sr-90 and electric field complex exposure group. The ODC activity was measured in rat's bone marrow cell every week. The results were summarized as follows: The ODC activitied was increased in X-ray irradiated, Sr-90 injected and Sr-90 and electric field complex exposed group as compared with that of control(p<0.05). The ODC activity was increased comparing that of control neither in X-ray and electric field complex exposed group nor electric field only exposed group. This result suggests that the electric field doesn't have myeloid carcinogenicity and myeloid cancer incidence caused by ionized radiation is suppressed by electric field exposure.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.250-255
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• 2009

This study performed and evaluated the performance test in 40 general X-ray units among diagnostic X-ray units, which were being used in hospitals of gyeongsangnam-do gimhae-si through X-ray tube variable limiting device ability test, the light field and X-ray field alignment test and collimation and beam alignment test of diagnostic X-ray unit. The results are as followings: In a variable beam limiting device ability test, the result of maximum X-ray field test showed that 4(10%) of were incongruent while the result of minimum X-ray field test represented that 5(12.5%) of were incongruent. The result of the light field and X-ray field alignment test showed 23(57.5%) of were within 2% of maximum permissible level and the other 17(42.5%) units were misalignment. The result of beam alignment test represented that 11(27.5%) coincided and another 11(27.5%) within $0.5^{\circ}$ respectively, 10(25%) were $0.6^{\circ}-1.5^{\circ}$ intervals, 7(17.5%) were $1.6^{\circ}-3^{\circ}$ and 1(2.5%) were more than $3^{\circ}$.

• ETRI Journal
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• v.35 no.6
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• pp.1164-1167
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• 2013

We correlate the failure in miniature X-ray tubes with the field emission gate leakage current of gated carbon nanotube emitters. The miniature X-ray tube, even with a small gate leakage current, exhibits an induced voltage on the gate electrode by the anode bias voltage, resulting in a very unstable operation and finally a failure. The induced gate voltage is apparently caused by charging at the insulating spacer of the miniature X-ray tube through the gate leakage current of the field emission. The gate leakage current could be a criterion for the successful fabrication of miniature X-ray tubes.

• 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.

• 순환기질환의공학회:학술대회논문집
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• 2006.04a
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• pp.28-36
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• 2006

The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

• International Journal of Vascular Biomedical Engineering
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• v.4 no.1
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• pp.1-8
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• 2006

The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

• Journal of radiological science and technology
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• v.44 no.6
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• pp.591-597
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• 2021

In the present study, we developed virtual reality education contents for radiation generator on radiation education field. The radiation generator was divided by module and even the X-ray exposure part was manufactured in detail for designing 3D models. The mechanical details of the X-ray exposure part, the function of adjusting field size of the X-ray, the function of moving the exposure part, and the demonstrating the principle of the X-ray tube were applied. For developing VR contents, the Unreal Engine was used. To evaluate the usefulness of virtual reality content, we used t-test by SPSS. The group used the simulator showed significantly higher levels of understanding of X-ray generation, X-ray irradiation unit composition, irradiation field size adjustment, irradiation unit position adjustment, and overall composition and function. We believe that this VR contents will be used well with radiation safe environment.

• Journal of radiological science and technology
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• v.11 no.2
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• pp.3-15
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• 1988

When X-rays were projected into a patient, there occured the phenomena such as penetration, absorption and scattering etc. The penetrating rays were recorded on films as X-ray image used for diagnosis but scattered rays caused the radiation hazard both to the patient, specialist and technicians. The soft tissue includes many organs which are sensitive to the radiation and in may occupy $40{\sim}50%$ of body weight. Therefore X-rays should be carefully projected to the patient and it is strongly recommended to analyse the distribution of X-rays, when ever the patient is exposed to X-rays. In this study, the distribution of X-ray according to the thickness, the radiation field and the tube voltages (kVp) in soft tissue, the following results were obtained: 1. Total transmitted rays which kept the step with X-ray tube voltage (kVp) increased in proportion to the increasing of X-ray tube voltage. 2. The scattered ray rate in the total transmitted ray was not significantly found with X-ray tube voltage. 3. The affecting factors of the scattered ray rate in total transmitted ray were shown through the radiation field and the thickness. 4. The dose of scattered ray by the angle was observed more in direction of primary ray ($0^{\circ}$) and back scattering ($160^{\circ}$) than in direction of $90^{\circ}$. 5. The more the distance from phantom to the patient should be less distribution of scattered ray.