• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.501-508
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• 2017

The dependence of CT scanning parameters on the CT number to physical density conversion from the CT image of CT and CBCT electron density phantom acquired by the CT scanner using in radiotherapy were analyzed by experiment. The CT numbers were independent of the tube current product exposure time, slice thickness, filter of image reconstruction, field of view and volume of phantom. But the CT numbers were dependent on the tube voltage and cross section of phantom. As a result, for physical density range above 0, the maximum CT number difference observed at the tube voltage between 90 and 120 kVp was 27%, and the maximum CT number difference observed between CT body and head electron density phantom was 15%.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.83-91
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• 2024

The purpose of this study was to determine the doppler fluid effects of carbonated water (CBW) in a bi-directional flow phantom model. A bi-directional flow phantom model was chosen to realize arterial and venous flow, and the structure of the inner and outer tanks allowed for fluid circulation and also made the size of the phantom small. Carbonated water (CBW), salt fluid (SAF), sugar fluid (SUF), and distilled water (DW) were used as fluids, and ultrasound scans were performed at depths of 1.5 cm and 3.0 cm from the surface of the tank, using B-mode and color Doppler effects. All fluids tested showed color Doppler effects, but CBW had the highest doppler shift and the least variation with depth. In conclusion, we determined that CBW was the most suitable fluid to be used as a doppler fluid and confirmed that the bubbles dissolved in CBW act as doppler scatterers, just like red blood cells inside human blood. Therefore, it is possible that CBW can be used as a blood-mimicking fluid in doppler ultrasound phantoms through further research, and this study will provide basic data.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.929-937
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• 2023

Human equivalent phantoms manufactured using 3D printers are cheaper and can be manufactured in a short time than conventional human phantoms. However, many phantoms are manufactured with less than 100 % of Infill Density, one of the 3D printer output setting variables. Therefore, this study compared the Bone Phantom CT number, which differs from the ratio of five Infill Density produced using a 3D printer, to the CT number of the actual human body Bone. In addition, the usefulness of the manufactured phantom was evaluated by producing a 100 % elbow joint phantom with Infill Density and setting the Infill Density to 100 % through CT number comparison for each tissue on computed tomography (CT). As a result, the Bone Phantom printed with 100 % Infill Density did not show the most statistically significant difference from the CT number value of the actual human Bone, and the CT number of each tissue did not show a statistically significant difference from the CT number value of each tissue of the actual human elbow joint.

• Korean Journal of Social Welfare
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• v.67 no.1
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• pp.263-288
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• 2015

This study is to research the mediating effects of optimism and quality of relationship which interpersonal traumatic experience influences posttraumatic growth. It focuss on verifying the impact of interpersonal traumatic experience to optimism and quality of relationship and the influence of optimism and quality of relationship to posttraumatic growth. And also it is to verify dual mediating effect between optimism and quality of relationship. Data for this study were collected through the use of a survey instrument completed by 405 interpersonal traumatic experience, 30-60 age group. Collected data were analysed by AMOS program, Structure Equation Model(SEM) was implemented to verify the mediating effect between optimism and quality of relationship. Finally, Phantom Variable was utilized for verification of indirect influence of a multi mediating effects. The findings of this study were as follows, First, the result shows that the higher level interpersonal traumatic experience, the higher posttraumatic growth they have. Second, it shows that optimism and quality of relationship have partial mediating effect between interpersonal traumatic experience and posttraumatic growth. Third, it was analyzed that optimism and quality of relationship had double mediating effect. Based on these findings, the research discussion reinforced the importance of intervene with its optimism and quality of relationship in the site of those who experience interpersonal trauma. Theological, political and practical implications of this study are as follows. First, it has a series of significance in terms of that this study confirmed its influence considering the quality of relationship from interpersonal experience among relevant factors of traumatic accident, optimism among individual factors, quality of relationship among environmental factors based on 'the crisis of life and the theory of individual growth'. econd, even though optimism and quality of relationship were proved as major predictors for posttraumatic growth of those who experience interpersonal traumatic, psychological support center for traumatic experience is not operated systematically in Korea. Third, this study implies that it should intervene mainly with its optimism and quality of relationship in the site of those who experience interpersonal trauma such as any abuses including sexual abuse, bullying, and divorce.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.585-596
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• 2016

This study was designed to examine the relationships among the levels of perceived stress, dietary behaviors, physical exercise, drinking, smoking, and relief from fatigue through sleep which affect the subjective happiness in adolescents. Based on the study findings, this paper proposes the basic data required for offering practical solutions to improve the subjective happiness of adolescents. IBM SPSS 20 and AMOS 23 were used to conduct frequency and descriptive analyses, in conjunction with Pearson's correlation coefficients, the AMOS bootstrapping method and phantom variables, for the raw data obtained from the 9,599 participants included in the 11th Korea Youth Risk Behavior Web-based Survey. Those factors having a direct effect on the subjective happiness of the adolescents were the level of perceived stress, relief from fatigue through sleep, physical exercise, dietary behavior and smoking. Perceived stress had an indirect effect on subjective happiness, and the analysis of the indirect effect and significance level of multiple mediators by means of phantom variables showed that, as well as perceived stress, relief from fatigue through sleep, physical exercise, dietary behaviors, and smoking also had indirect effects on subjective happiness. Consequently, a multidisciplinary approach is needed to optimize the subjective happiness in adolescents and financial support for environmental improvements is particularly necessary.

• The Journal of the Acoustical Society of Korea
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• v.28 no.7
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• pp.661-667
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• 2009

Trabecular-bone-mimicking phantoms consisting of parallel-nylon-wire arrays were used to investigate correlations of phase velocity and attenuation coefficient with structural properties in trabecular bone. Trabecular separation (Tb.Sp) of the 7 trabecular-bone-mimicking phantoms ranged from 300 to $900\;{\mu}m$ and volume fraction (VF) from 1.6% to 8.7%. Phase velocity and attenuation coefficient of the phantoms were measured by using a through-transmission method in water, with a matched pair of broadband unfocused transducers with a diameter of 12.7 mm and a center frequency of 1 MHz. Phase velocity and attenuation coefficient at 1 MHz decreased almost linearly with increasing Tb. Sp and increased almost linearly with increasing VF. The simple and multiple linear regression models with phase velocity and attenuation coefficient as independent vanables and Tb.Sp and VF as dependent variables demonstrated that the coefficients of determination for the prediction of VF were higher than those for the prediction of Tb.Sp. The results obtained in the trabecular-bone-mimicking phantoms consisting of parallel-nylon-wire arrays were consistent with those in human trabecular bone suggesting that the structural properties can be estimated from the measurements of phase velocity and attenuation coefficient in trabecular bone.

• Progress in Medical Physics
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• v.15 no.4
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• pp.202-209
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• 2004

Flat panel based digital radiography (DR) systems have recently become useful and important in the field of diagnostic radiology. For DRs with amorphous silicon photosensors, CsI(TI) is normally used as the scintillator, which produces visible light corresponding to the absorbed radiation energy. The visible light photons are converted into electric signal in the amorphous silicon photodiodes which constitute a two dimensional array. In order to produce good quality images, detailed behaviors of DR detectors to radiation must be studied. The relationship between air exposure and the DR outputs has been investigated in many studies. But this relationship was investigated under the condition of the fixed tube voltage. In this study, we investigated the relationship between the DR outputs and X-ray in terms of the absorbed energy in the detector rather than the air exposure using SPEC-l8, an X-ray energy spectrum model. Measured exposure was compared with calculated exposure for obtaining the inherent filtration that is a important input variable of SPEC-l8. The absorbed energy in the detector was calculated using algorithm of calculating the absorbed energy in the material and pixel values of real images under various conditions was obtained. The characteristic curve was obtained using the relationship of two parameter and the results were verified using phantoms made of water and aluminum. The pixel values of the phantom image were estimated and compared with the characteristic curve under various conditions. It was found that the relationship between the DR outputs and the absorbed energy in the detector was almost linear. In a experiment using the phantoms, the estimated pixel values agreed with the characteristic curve, although the effect of scattered photons introduced some errors. However, effect of a scattered X-ray must be studied because it was not included in the calculation algorithm. The result of this study can provide useful information about a pre-processing of digital radiography.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.313-320
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• 1998

Tri-phasic pulsatile flow is the general flow pattern of human circulary system. In emulating the various situation of cardiovascular system, it is essential to make tri-phasic source flow. To emulate tri-phasic pulsatile flow, we used electro-hydronic style LVAD(Left Ventricular Assist Device) with glass phantom and rubber tube. We have selected control parameters and examined the changing effect of each parameter by using Doppler ultrasound. In this experiment, it was shown that the distal compliance and the break time were the major factors to form tri-phasic flow. The results make it possible to emulate and explain the various situation of human vascular system. In this point, this results will be an useful method in the clinic application.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.485-495
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• 2020

The purpose of this study was to examine the role of self-esteem (SE) and cooperation (CO) in the effect of parental attitudes (PA) as perceived by children on the quality of peer relationships (PR). To this end, the data of 1299 boys and 1278 girls in 4th grade were analyzed using the Korean Children and Youth Panel Survey data. The correlation analysis, confirmatory factor analysis, structural equation modeling using phantom variables and bootstrapping were performed by using SPSS and AMOS programs. The results of this study are as follows. First, perceived PA had a significant effect on SE, CO, and PR, SE had a significant effect on CO and PR, and CO had a significant effect on PR. Second, the serial multi-mediating model that assumed that SE and CO mediate the relationship between PA and PR was found to be appropriate. These results suggest that it is important to consider the child's self-esteem and cooperation with parenting attitudes to improve the child's peer relationship. Future research and clinical implications were discussed.

• Journal of the Korea Society of Computer and Information
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• v.27 no.4
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• pp.119-125
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• 2022

In this paper, we intend to examine the mediating effects of self-esteem and school life adaptation in the path between cultural adaptation stress and life satisfaction of multicultural adolescents, and propose ways to improve the life satisfaction level of multicultural adolescents. As analysis data for this purpose, the 4th, 5th, and 6th panel data of multicultural youth of the Korea Youth Policy Research Institute were used, and multivariate potential growth model analysis was performed using the statistical programs SPSS 23.0 and Amos 23.0 version. In addition, the individual mediating effects of self-esteem and school life adaptation were verified using phantom variables. As a result of the analysis, it was possible to confirm the longitudinal mediating effects of self-esteem and school life adaptation, which suggests that multi-dimensional efforts are needed to improve self-esteem and school life adaptation level to improve the life satisfaction level of multicultural adolescents. Therefore, based on the results of this study, practical measures to improve the life satisfaction of multicultural adolescents were presented in detail.