• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.117-128
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• 2018

In this paper, compact linear dual polarized series-fed $1{\times}2$ linear and $2{\times}2$ planar arrays antennas for airborne SAR applications are proposed. The proposed antenna design consists of a square radiating patch that is placed on top of the substrate, a quarter wave transformer and $50-{\Omega}$ matched transformer. Matching between a radiating patch and the $50-{\Omega}$ microstrip line is accomplished through a direct coupled-feed technique with the help of an impedance inverter (${\lambda}/4$ impedance transformer) placed at both horizontal and vertical planes, in the case of the $2{\times}2$ planar array. The overall size for the prototype-1 and prototype-2 fabricated antennas are $1.9305{\times}0.9652{\times}0.05106{{\lambda}_0}^3$ and $1.9305{\times}1.9305{\times}0.05106{{\lambda}_0}^3$, respectively. The fabricated structure has been tested, and the experimental results are similar to the simulated ones. The CST MWS simulated and vector network analyzer measured reflection coefficient ($S_{11}$) results were compared, and they indicate that the proposed antenna prototype-1 yields the impedance bandwidth >140 MHz (9.56-9.72 GHz) defined by $S_{11}$<-10 dB with 1.43%, and $S_{21}$<-25 dB in the case of prototype-2 (9.58-9.74 GHz, $S_{11}$< -10 dB) >140 MHz for all the individual ports. The surface currents and the E- and H-field distributions were studied for a better understanding of the polarization mechanism. The measured results of the proposed dual polarized antenna were in accordance with the simulated analysis and showed good performance of the S-parameters and radiation patterns (co-pol and cross-pol), gain, efficiency, front-to-back ratio, half-power beam width) at the resonant frequency. With these features and its compact size, the proposed antenna will be suitable for X-band airborne synthetic aperture radar applications.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.319-325
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• 1999

Direct current(d.c.)leakage current voltage characteristics of radio-frequencymagnetron sputtered BaTa\sub 2\O\sub 6\ film capacitors with aluminum(A1) top and indium tin oxide (ITO) bottom electrodes have been investigatedas a function of applied field and temperature. In order to study surfacetreatment effect on the electrical characteristics of as-deposited film weperformed exposure of oxygen plasma on $BaTa_2O_6$ surface. d. c.current-voltage (I-V), bipolar pulse charge-voltage (Q-V), d. c. current-time (I-t) andcapacitance-frequency (C-f) analysis were performed on films. All ofthe films exhibita low leakage current, a high breakdown field strength (3MV/cm-4.5MV/cm), and high dielectric constant (20-30). From the temperature dependence of leakage current,we can conclude that the dominant conduction mechanism is ascribed toSchottky emission at high electric field (>1MV/cm) and hopping conduction at lowelectric field (<1MV/cm). According to our results, the oxide plasma surfacetreatmenton as-deposited $BaTa_2O_6$ resulted in lowering interfacebarrier height and thus, leakage current when a negative voltage applied to the A1 electrode. This can be explained by reduction of surface contamination via etching surface and filling defects such as oxygen vacancies.

• 대한기계학회논문집B
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• 제30권5호
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• pp.413-421
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• 2006

The bubble dynamics induced by direct laser heating is experimentally analyzed as a first step to assess the technical feasibility of laser-based ink-jet technology. To understand the interaction between laser light and ink, the absorption spectrum is measured for various ink colors and concentrations. The hydrodynamics of laser-generated bubbles is examined by the laser-flash photography. When an Ar ion laser pulse (wavelength 488 nm) with an output power up to 600 mW is incident on the ink solution through a transparent window, a hemispherical bubble with a diameter up to ${\sim}100{\mu}m$ can be formed with a lifetime in a few tens of microsecond depending on the laser power and the focal-spot size. Parametric study has been performed to reveal the effect of laser pulse width, output power, ink concentration, and color on the bubble dynamics. The results show that the bubble generated by a laser pulse is largely similar to that produced by a thin-film heater. Consequently, the present work demonstrates the feasibility of developing a laser-actuated droplet generation mechanism for applications in ink-jet print heads. Furthermore, the results of this work indicate that the droplet generation frequency is likely to be further increased by optimizing the process parameters.

• Journal of Nutrition and Health
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• 제35권10호
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• pp.1089-1103
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• 2002

The purpose of this study is to identify factors influencing a health-promoting lifestyle among highly educated, married women with or without work outside the home. It is a direct interview, cross-sectional study. Subjects were 250 married, unemployed women and 236 married women employed as teachers. Women who have not graduated college, work only part-time or have no current spouse were excluded. The instruments used were the Health-Promoting Lifestyle Profile (Walker, et al., 1987) and the Habitual Physical Activity Questionnaire (Backe, et al., 1982), The HPLP scores of the employed, married women were significantly lower than those for unemployed respondents. for both groups of respondents, the self-actualization subscale was the highest score and the exercise subscale was the lowest score. The HPLP indicated that exercise is a very weak area. Thus, an increase in exercise time and frequency, especially for highly educated, married women, is suggested. Multiple regression analysis revealed that a health-promoting lifestyle of unemployed, married women was affected by sports activity, leisure-time activity, depression and satisfaction of role allotment. On the other hand, a health-promoting lifestyle of employed, married women was affected by sports activity, leisure-time activity, stress, self-perceived economic status, coffee consumption, husband's help, and maid's help. That is, with more sports activity and leisure-time activity, less depression and more satisfaction of role allotment, unemployed, married women would have higher HPLP scores. Also, with more sports activity and leisure-time activity, less stress, better self-perceived economic status, less coffee consumption, more husband's help and more maid's help, employed, married women would have higher HPLP scores. The results indicate that sports activity and leisure-time activity were the first and the second determinants of health-promoting lifestyle respectively. Therefore, an exercise-centered health-promoting program for highly educated, married women is suggested in the community or workplace. Especially, the program should be designed to be easily approachable for highly educated, employed married women who have more of a role burden compared to unemployed women.

• Journal of Veterinary Science
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• 제22권3호
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• pp.38.1-38.17
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• 2021

Background: The feline viral rhinotracheitis, calicivirus, and panleukopenia (FVRCP) vaccine, prepared from viruses grown in the Crandell-Rees feline kidney cell line, can induce antibodies to cross-react with feline kidney tissues. Objectives: This study surveyed the prevalence of autoantibodies to feline kidney tissues and their association with the frequency of FVRCP vaccination. Methods: Serum samples and kidneys were collected from 156 live and 26 cadaveric cats. Antibodies that bind to kidney tissues and antibodies to the FVRCP antigen were determined by enzyme-linked immunosorbent assay (ELISA), and kidney-bound antibody patterns were investigated by examining immunofluorescence. Proteins recognized by antibodies were identified by Western blot analysis. Results: The prevalences of autoantibodies that bind to kidney tissues in cats were 41% and 13% by ELISA and immunofluorescence, respectively. Kidney-bound antibodies were observed at interstitial cells, apical border, and cytoplasm of proximal and distal tubules; the antibodies were bound to proteins with molecular weights of 40, 47, 38, and 20 kDa. There was no direct link between vaccination and anti-kidney antibodies, but positive antibodies to kidney tissues were significantly associated with the anti-FVRCP antibody. The odds ratio or association in finding the autoantibody in cats with the antibody to FVRCP was 2.8 times higher than that in cats without the antibody to FVRCP. Conclusions: These preliminary results demonstrate an association between anti-FVRCP and anti-cat kidney tissues. However, an increase in the risk of inducing kidney-bound antibodies by repeat vaccinations could not be shown directly. It will be interesting to expand the sample size and follow-up on whether these autoantibodies can lead to kidney function impairment.

• 천문학회지
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• 제54권4호
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• pp.129-137
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• 2021

It has been established that the acoustic mode parameters of the Sun and Sun-like stars vary over activity cycles. Since the observed variations are not consistent with an activity-related origin, even Sun-like stars showing out-of-phase changes of mode frequencies and amplitudes need to be carefully studied using other observational quantities. In order to test whether the presumed relations between the global seismic parameters are a signature of the stellar activity cycle, we analyze the photometric light curve of HD 49933 for which the first direct detection of an asteroseismic signature for activity-induced variations in a Sun-like star was made, using observations by the CoRoT space telescope. We find that the amplitude of the envelope significantly anti-correlates with both the maximum frequency of the envelope and the width of the envelope unless superflare-like events completely contaminate the light curve. However, even though the photometric proxy for stellar magnetic activity appears to show relations with the global asteroseismic parameters, they are statistically insignificant. Therefore, we conclude that the global asteroseismic parameters can be utilized in cross-checking asteroseismic detections of activity-related variations in Sun-like stars, and that it is probably less secure and effective to construct a photometric magnetic activity proxy to indirectly correlate the global asteroseismic parameters. Finally, we seismically estimate the mass of HD 49933 based on our determination of the large separation of HD 49933 with evolutionary tracks computed by the MESA code and find a value of about 1.2M_☉ and a sub-solar metallicity of Z = 0.008, which agrees with the current consensus and with asteroseismic and non-asteroseismic data.

• 한국표면공학회지
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• 제55권2호
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• pp.91-95
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• 2022

ZnO single layer (60 nm thick) and ZnO with Ag interlayer (ZnO/Ag/ZnO; ZAZ) films were deposited on the glass substrates by using radio frequency (RF) and direct current (DC) magnetron sputter to evaluate the effectiveness of Ag interlayer on the optical visible transmittance and the conductivity of the films. In the ZAZ films, the thickness of ZnO layers was kept at 30 nm, while the Ag thickness was varied as 5, 10, 15 and 20 nm. In X-ray diffraction (XRD) analysis, ZnO films show the (002) diffraction peak and ZAZ films also show the weak ZnO (002) peak and Ag (111) diffraction peak. As a thickness of Ag interlayer increased to 20 nm, the grain size of the Ag films enlarged to 11.42 nm and the optical band gap also increased from 4.15 to 4.22 eV with carrier concentration increasing from 4.9 to 10.5×10²¹ cm^-3. In figure of merit measurements, the ZAZ films with a 10 nm thick Ag interlayer showed the higher figure of merit of 4.0×10^-3 Ω^-1 than the ZnO single layer and another ZAZ films. From the experimental result, it is assumed that the Ag interlayer enhanced effectively the opto-electrical performance of the ZAZ films.

• Tribology and Lubricants
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• 제39권4호
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• pp.139-147
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• 2023

Cavitation phenomena observed during the operation of a submerged plain journal bearing (PJB) can affect bearing performance parameters such as dynamic coefficients, whirl frequency ratio, and critical mass. This study presents numerical solutions of the Reynolds equation for steadily and dynamically loaded submerged PJBs with half-Sommerfeld (HS), Reynolds, and Jakobsson-Floberg-Olsson (JFO) cavitation models when the supply pressure is larger or equal to the cavitation pressure. The loads at various eccentricity ratios are identical; however, the attitude angle is approximately 6% smaller when the eccentricity ratio is between 0.2 and 0.7 and the JFO model is used, compared to that when the Reynolds model is used. Dynamic coefficients obtained with the HS and Reynolds model show good agreement with each other, except for k_xz, which is sensitive to changes in the force normal to the rotor weight, and is attributed to the difference in the attitude angle obtained with each cavitation model. Stiffness coefficients are determined using the pressure distribution in the film, and therefore, when the JFO model is used, the direct stiffness coefficients are affected and show opposite signs for most eccentricity ratios. The mass-conservative JFO model can predict at least a 30% smaller critical mass compared to that using the HS and Reynolds models. Thus, the instability analysis results can change based on the cavitation model used in a submerged PJB. The results of this research indicate that the JFO model should be used when designing a rotor system supported by submerged PJBs.

• 가정∙방문간호학회지
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• 제31권1호
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• pp.89-98
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• 2024

Purpose: This descriptive research study is intended to develop practical strategies for enhancing the quality of elderly care by evaluating the levels of ageism and compassion competence among clinical nurses and their impact on geriatric nursing performance. Methods: This study involved 162 nurses who provided direct care to elderly patients in a department with many such patients. Of the 161 returned questionnaires, 150 were analyzed, excluding 11 that had insincere or missing responses. To analyze the data, a comprehensive approach was employed using the IBM SPSS 27.0 program that included calculations of frequency and percentage, mean, and standard deviation, as well as more complex statistical tests such as the independent t-test, one-way ANOVA, Pearson's correlation coefficients, and hierarchical linear regression analysis. Results: Compassion competence was significantly positively correlated with elderly care and negatively correlated with ageism. This study conclusively demonstrates that compassion competence among nurses in geriatric nursing situations plays a crucial role in provision of quality nursing grounded in understanding and respect for the elderly. Consequently, it is imperative to develop educational strategies tailored to each career stage of nursing practice to further enhance effective elderly care. Conclusion: This study conclusively demonstrates that compassion competence in geriatric nursing situations plays a crucial role in provision of quality nursing grounded in understanding and respect for the elderly. Consequently, it is imperative to develop educational strategies tailored to each career stage of nursing practice to further enhance effective elderly care.

• 한국직업건강간호학회지
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• 제33권3호
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• pp.83-94
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• 2024

Purpose: This study aimed to investigate the effects of rehabilitation hospital nurses' perception of patient safety culture, nursing professionalism, and nursing work environment on patient safety nursing activities. Methods: A cross-sectional design was used with a convenience sample of 230 nurses with more than six months of experience working in rehabilitation hospitals located in D Metropolitan City, South Korea. Data were collected from October 23 to 31, 2023 through a self-administered questionnaire and analyzed by descriptive statistics, independent t-test, one-way ANOVA with post-verification of Scheffé test, Pearson's correlation coefficient, and multiple stepwise regression analysis using SPSS 28.0. Results: The average scores were 3.73±0.35 for perception of patient safety culture, 3.54±0.47 for nursing professionalism, 2.67±0.49 for nursing work environment, and 4.68±0.45 for patient safety nursing activities. Patient safety nursing activities was significantly positively correlated with perception of patient safety culture, nursing professionalism, and nursing work environment. Experience of reporting incidents (β=.19, p=.002), communication and procedure (β=.18, p=.003), frequency of reporting (β=.18, p=.002), total clinical experience (β=.17, p=.004), patient safety (β=.17, p=.005), and direct supervisor/manager (β=.17, p=.008) affected patient safety nursing activities in rehabilitation hospitals. Conclusion: Perception of patient safety culture may increase rehabilitation hospital nurses' patient safety nursing activities.