• Journal of Radiation Protection and Research
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• v.46 no.4
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• pp.160-169
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• 2021

Background: Dual-energy X-ray images (DEI) can distinguish or improve materials of interest in a two-dimensional radiographic image, by combining two images obtained from separate low and high energies. The concepts of DEI performance describing the performance of double-exposure DEI systems in the Fourier domain been previously introduced, however, the performance of double-exposure DEI itself in terms of various parameters, has not been reported. Materials and Methods: To investigate the DEI performance, signal-difference-to-noise ratio, modulation transfer function, noise power spectrum, and noise equivalent quanta were used. Low- and high-energy were 60 and 130 kVp with 0.01-0.09 mGy, respectively. The energy-separation filter material and its thicknesses were tin (Sn) and 0.0-1.0 mm, respectively. Noise-reduction (NR) filtering used the Gaussian-filter NR, median-filter NR, and anti-correlated NR. Results and Discussion: DEI performance was affected by Sn-filter thickness, weighting factor, and dose allocation. All NR filtering successfully reduced noise, when compared with the dual-energy (DE) images without any NR filtering. Conclusion: The results indicated the significance of investigating, and evaluating suitable DEI performance, for DE images in chest radiography applications. Additionally, all the NR filtering methods were effective at reducing noise in the resultant DE images.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.957-964
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• 2021

Fluorine-18 used in PET/CT scans is a radioactive isotope that emits positrons, and high energy annihilation gamma rays and beta rays cause exposure to radiation workers. In this study, as part of a plan to reduce the exposure dose of radiation workers working in the Department of Nuclear Medicine, the cause of the low shielding efficiency of Apron for F-18 was identified, and the effectiveness of the Apron double-shielded with acrylic was evaluated. L-Block, Apron+acrylic, Apron, Acrylic+Apron, and Acrylic five shields are used to measure the dose, and the tendencies were compared by performing a Monte Carlo simulation. As a result, it was found that the shielding rate of Apron double shielded with acrylic was about 4 to 8% higher than that of Apron single shielded. To the extent that it does not significantly affect the user's activity, double-shielded personal protective clothing with an appropriate acrylic thickness could help reduce radiation workers' exposure.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.12-21
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• 2017

In this study, we divided attention to mobile contents into two dimensions (i.e., exposure and involvement), and explored the characteristics of and the relationship between the attention behaviors, using contents data from Pikicast. First, this study investigated the relationship between exposure and involvement in order to examine whether double-jeopardy effects appear in mobile contents as well. In addition, we examined how different attention behaviors differ according to platform and subject attributes(i.e., soft and hard). As a result, we found that there was a positive correlation between exposure and involvement in mobile platforms. Also, we found that the attention behaviors, especially sharing behaviors, were different in each platform. In terms of subject attributes, the attention indices such as the number of comments and sharing, which were immediate responses, were related to the soft content, whereas the attention indices such as the consumption time and the complete-read rate were related to the hard content requiring cognitive effort.This study is meaningful to understand the essence of the attention behavior in the mobile environment from a content - oriented perspective rather than the most existing research with a user - centered perspective.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3211-3223
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• 1996

In this paper, the propagation of elastic wave generated by loading impact to plates made of isotropic of anisotropic material was studied. And the influence of boundary conditions (free or clamped edge) upon the reflection of elastic wave was anlyzed. Also, double exposure holographic interferometer using ruby pulse laser was formed in order to investigate transient waves. Before the elasitc wave was reflected from the edges, the elastic wave of isotropic plate such as aluminum plate showed circular interferometric fringe pattern, whereas that of anisotropic plate such as epoxy composite laminates showed elliptical one. And the transverse displacement curves obtained from experiment and theory for both plates agreed well. Also, the waves reflected from the boundary edges showed much differences according to the boundary condition of edges.

• Journal of radiological science and technology
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• v.24 no.1
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• pp.17-22
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• 2001

Medical X-ray examination are increased double for the last $6{\sim}8$ years. Therefore a patient exposure dose should be decrease half every 7 years. We made an experiment on copper filter thickness to decrease a patient exposure dose up to half and compared to the Image quality by MTF. The results as follow 1. A thin region like extremities needs a thicker Cu filter as compared a thick region. 2. 1/2 reduction filter must be thicker when kVp Increase. 3. Exposure factor should be increas when using 1/2 reduction filter ; extremity is 4.0 times, chest 2.9 times, skull 1.62 times, and abdomen 1.58 times 4. The MTF of using 1/2 reduction filter is lower than without filter. But no difference of visual image. 5. 1/2 reduction filter compared with double speed screen showed almost same image quality.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.418-421
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• 1988

Holographic interferometry is applied in dental research to study the motion of teeth and the deformation of the associated facial structure. We consider double exposure holographic interferometry which has limiting factors such as the stability of fringes, the recording time, the amount of exposure, the localization of fringes and sensitivity. These factors are taken into account to make interferogram. The resulting interferogram gives fringe pattern which is analyzed qualitatively to determine the relative rotation and the deformation of the facial structure.

• Korean Journal of Cognitive Science
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• v.6 no.1
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• pp.47-71
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• 1995

A psychological disturbance caused by letters in double image was termed as'letter sickness'.The effects of stimulus exposure time and letter familiarity on the letter sickness were measured to test a hypothesis that disturbances in eye movement and recognition stages is the cause of letter sickness.Letter sickness incteased significantly as stimulus exposure time lengthened from 50ms,100ms,to 3000ms.It was also significantly higher with familiar Hangul letters as compared with less familiar foreign letters and meaningless words as compared with meaningful words,respectively.These experimental findings imply that letter sickness is caused by the failure of adjusting eye movements to dismiss the double images.that the more familiar the letters.the more strongly the letter-identification process is commotted,resulting in the increased effect of disturbance from double image.and that the disturbance effect of double image is amplified when it is hard to extract the meaning from familiar letters.An experiment where subjects were made to learn Braille-like symbols consisting of 6 dots to test the hypothesis that the stronger the tendency to process the meaning of a symbol,the stronger becomes letter sickness due to double image,also showed that letter sickness significantly increased as a function of learning.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.213-216
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• 2002

A double-heterostructure AIGaAs/GaAs PHEMT (Pseudomorphic High Electron Mobility Transistor) using digital recess has been successfully realized. Futhermore, the differences of gm,nax, fT, fmax between two samples are as low as 0.62%, 1.58% and 2.56 % respectively. Experimental results are presented demonstrating the etch rate and Process invariability with respect to hydrogen peroxide and acid exposure times with uniformity among devices on a sample.

• Asian Journal for Public Opinion Research
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• v.12 no.2
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• pp.122-141
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• 2024

Drawing on mere exposure effect, we proposed that more exposure to a city, as measured by the number of channels of exposure, would increase familiarity, city image, and intention to visit that city. We conducted a survey of university students in seven Asian countries, asking them about a total of 14 cities, at least one from each of the surveyed countries. Exposure was found to be a significant antecedent and was most powerful when mediated by familiarity. Some types of exposure were stronger than others. Personal exposure, in the form of having visited a city or knowing someone who has, was the strongest type of exposure, with more than double the effect of media exposure. Social media, which is difficult to classify as either personal or media, was assessed separately and had a much smaller effect. The mere exposure effect exists whether the intention to visit a city is related to pleasure (tourism) or business.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.1
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• pp.56-66
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• 1996

In this study, the characteristics of generation and propagarion of transient wave induced in the assembly of four collecting plate upon the propagation of waves are analyzed. Also double exposure holographic inteferometry using ruby pulse laser is built in order to investigate the propagation of transient waves generated by impact load. When impact load was applied at edge of connecting band, the vibration of collecting plates was generated from the contact points between collecting plate and band which connects four collecting plates. Waves generated from the lower part and those reflected from the upper part were mixed as time went on and then formed very complex shapes. Also, when impact load was aplied at center of collecting plate, the waves propagating across the convexo-concave plane were reflected partly at curved section. Therefore the vibration amplitude was decreased as the transiet waves were propagated through the convexo-concave plane.