• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.474-487
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• 2011

Bars of OFHC Cu with the diameter of 45 mm were processed by equal channel angular pressing up to 16 passes via route $B_c$, and homogeneity of their microstructures and mechanical properties was examined at every four passes which develop the equiaxed ultrafine grains. In general, overall hardness, yield strength and tensile strength increased by 3, 7, and 2 times respectively compared with those of unECAPed sample. Cross-sectional hardness exhibited a concentric distribution. Hardness was the highest at the center of bar and it decreased gradually from center to surface. After 16 passes, overall hardness decreased due to recovery and partial recrystallization. Regardless of the number of passage, yield strength and tensile strength were quite uniform at all positions, but elongation showed some degree of scattering. At 4 passes, coarse and ultrafine grains coexisted at all positions. After 4 passes, uniform equiaxed ultrafine grains were obtained at the center, while uniform elongated ultrafine grains were manifested at the upper half position. At the lower half position, grains were equiaxed but its size were inhomogeneous. It was found that inhomogeneity of grain morphology and grain size distribution at different positions are to be attributed to scattering in elongation but they did not affect strength. The present results reveal the high potential of practical application of equal channel angular pressing on fabrication of large-sized ultrafine grained bars with quite homogeneous mechanical properties.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.88-96
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• 2008

Thermal evaporated 10 nm-$Ni_{50}Co_{50}$/(70 nm-poly)Si films were deposited to examine the energy saving properties of silicides formed by rapid thermal annealing at temperature ranging from 500 to $1,100^{\circ}C$ for 40 seconds. Thermal evaporated 10 nm-Ni/(70 nm-poly)Si films were also deposited as a reference using the same method for depositing the 10 nm-$Ni_{50}Co_{50}$/(70 nm-poly)Si films. A four-point probe was used to examine the sheet resistance. Transmission electron microscopy (TEM) and X-ray diffraction XRD were used to determine cross sectional microstructure and phase changes, respectively. UV-VIS-NIR and FT-IR (Fourier transform infrared spectroscopy) were used to examine the near-infrared (NIR) and middle-infrared (MIR) absorbance. TEM analysis confirmed that the uniform nickel-cobalt composite silicide layers approximately 21 to 55 nm in thickness had formed on the single and polycrystalline silicon substrates as well as on the 25 to 100 nm thick nickel silicide layers. In particular, nickel-cobalt composite silicides showed a low sheet resistance, even after rapid annealing at $1,100^{\circ}C$. Nickel-cobalt composite silicide and nickel silicide films on the single silicon substrates showed similar absorbance in the near-IR region, while those on the polycrystalline silicon substrates showed excellent absorbance until the 1,750 nm region. Silicides on polycrystalline substrates showed high absorbance in the middle IR region. Nickel-cobalt composite silicides on the poly-Si substrates annealed at $1,000^{\circ}C$ superior IR absorption on both NIR and MIR region. These results suggest that the newly proposed $Ni_{50}Co_{50}$ composite silicides may be suitable for applications of IR absorption coatings.

• Korean Journal of Metals and Materials
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• v.46 no.3
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• pp.159-168
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• 2008

Thermally-evaporated 10 nm-Ni/1 nm-Ru/(30 nm or 70 nm-poly)Si structures were fabricated in order to investigate the thermal stability of Ru-inserted nickel monosilicide. The silicide samples underwent rapid thermal anne aling at $300{\sim}1,100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution X-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively. Transmission electron microscope and scanning probe microscope(SPM) were used to determine the cross-sectional structure and surface roughness. The silicide, which formed on single crystal silicon and 30 nm polysilicon substrate, could defer the transformation of $Ni_2Si $i and $NiSi_2 $, and was stable at temperatures up to $1,100^{\circ}C$ and $1,100^{\circ}C$, respectively. Regarding microstructure, the nano-size NiSi preferred phase was observed on single crystalline Si substrate, and agglomerate phase was shown on 30 nm-thick polycrystalline Si substrate, respectively. The silicide, formed on 70 nm polysilicon substrate, showed high resistance at temperatures >$700^{\circ}C$ caused by mixed microstructure. Through SPM analysis, we confirmed that the surface roughness increased abruptly on single crystal Si substrate while not changed on polycrystalline substrate. The Ru-inserted nickel monosilicide could maintain a low resistance in wide temperature range and is considered suitable for the nano-thick silicide process.

• Design & Manufacturing
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• v.14 no.4
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• pp.11-16
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• 2020

In this study, forming of carbon composite parts was performed using an injection/compression molding process. An impregnation of matrix is determined by ability of wet and flow rate between the matrix and reinforcement. The flow rate of matrix passing through the reinforcements is a function of permeability of reinforcement, a viscosity of matrix and pressure gradient on molding, and the viscosity of the matrix depends on the mold temperature, molding pressure and shear strain of matrix. Therefore, compression molding experiment was conducted using a heating mold in order to confirm the possibility of matrix impregnation. The impregnation of the matrix through the porosities between the woven yarns was confirmed by the cross-sectional SEM image of compression molded parts. An injection molding process was also performed at a short cycle time, high molding pressure and low mold temperature than those of compression experiment conditions. Deterioration of impregnation on the surface of molded parts were caused by these injection conditions and it could be the reason of decreasing the maximum tensile strength. In order to improve impregnation of matrix on the surface, injection/compression molding and insert-over molding were applied. As a result of applying injection/compression molding and insert-over molding, it was shown that the improvement of impregnation on the surface and the maximum tensile strength was increased about 2.8 times than the virgin matrix.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.90-113
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• 2021

Electronic Records Management System (ERMS) is a computer program or set of applications that is utilized for keeping up to date records along with their storage. ERMS has been extensively utilized for enhancing the performance of academic institutions. The system assists in the planning and decision-making processes, which in turn enhances the competencies. However, although ERMS is significant in supporting the process of decision-making, the majority of organizations have failed to take an initiative to implement it, taking into account that are some implementing it without an appropriate framework, and thus resulted in the practice which does not meet the accepted standard. Therefore, this study identifies the factors influencing the adoption of ERMS among employees of HLI in Yemen and the role of such adoption in the decision-making process, using the Unified Theory of Acceptance and Use of Technology (UTAUT) along with Technology, Organization and Environment (TOE) as the underpinning theories. The study conducts a cross-sectional survey with a questionnaire as the technique for data collection, distributed to 364 participants in various Yemeni public Higher Learning Institutions (HLI). Using AMOS as a statistical method, the findings revealed there are significant and positive relationships between technology factors (effort expectancy, performance expectancy, IT infrastructure and security), organizational factors (top management support, financial support, training, and policy),environmental factors (competitiveness pressure, facilitating conditions and trust) and behavioral intention to adopt ERMS, which in return has a significant relationship with the process of decision-making in HLI. The study also presents a variety of theoretical and empirical contributions that enrich the body of knowledge in the field of technology adoption and the electronic record's domain.

• Tuberculosis and Respiratory Diseases
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• v.84 no.2
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• pp.140-147
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• 2021

Background: For generations, cigarette smoking has presented an important public health concern. This study aimed to compare the health-promoting behavior, exercise capacity, physical activity level, health literacy, and knowledge level of smoking-related diseases between smokers and non-smokers. Methods: The study included 71 smokers (mean age, 32.69±8.55 years) and 72 non-smokers (mean age, 31.88±9.94 years) between the ages of 20 and 60 years. Assessments included a 6-minute walking test (6MWT), Godin Leisure-Time Physical Activity Questionnaire, Health-Promoting Lifestyle Profile II (HPLP-II), Cardiovascular Risk Factors Knowledge Level Scale (CARRF-KL), Asthma/COPD Awareness Questionnaire, the World Health Organization Quality of Life-Bref questionnaire (WHOQoL-Bref [TR]), and Health Literacy Questionnaire (HLQ). Results: The results from the study show that the number of coronary artery disease risk factors measured significantly higher among the smoker group members when compared to that of the non-smoker group members (p=0.001). Smokers had significantly lower %6MWT distance than non-smokers (84.83±4.72 and 93.45±7.16, respectively; p<0.05). However, there were no significant differences between the smokers and non-smokers in terms of physical activity, CARRF-KL, HLQ, WHOQoL-Bref, and HPLP-II subscales or total scores (p>0.05). Additionally, while only forty-one smokers (57.7%) were active, 48 of the non-smoker group was active (66.7%). Conclusion: Smokers suffer greater negative effects to their exercise capacity in comparison to non-smokers. Although smokers and non-smokers have similar levels of health literacy and similar levels of knowledge about cardiovascular disease risk factors and obstructive lung diseases, health professionals could continue to further increase individuals' awareness of smoking-related risk factors and continue to emphasize the importance of physical activity and exercise for protecting cardiopulmonary health.

• Journal of Korean Critical Care Nursing
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• v.14 no.2
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• pp.12-23
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• 2021

Purpose : The purposes of this study were to examine the levels of job stress, perceptions of the patient safety culture, and patient safety nursing activities, and to identify factors influencing patient safety nursing activities among intensive care unit (ICU) nurses. Methods : For this cross-sectional study, data were collected from 161 ICU nurses working in two university-affiliated hospitals in Gyeonggi-do between June 30 and July 30, 2020. The data were analyzed with descriptive statistics, an independent t-test, a one-way ANOVA, the Pearson correlation method, and multiple regression using the SPSS program. Results : The average levels of job stress, perception of patient safety culture, and patient safety nursing activities were 3.48, 3.44, and 4.45 out of 5, respectively. Multiple regression showed that perception of patient safety culture and career in current workplace were found to be statistically significant correlates of patient safety nursing activities. Conclusion : In order to promote patient safety nursing activities, patient safety culture needs to be incorporated into the education of ICU nurses. Perception of patient safety should be enhanced to improve patients safety nursing activity.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.4
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• pp.403-412
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• 2021

Purpose: This study aimed to determine the serum 25-hydroxy-vitamin D (25(OH)D) status of breastfed infants less than six months old and their mothers, and factors affecting the status. Methods: This cross-sectional study was done on breastfed, term, Filipino infants less than six months old who were seen at local health centers and clinics in an urban area. The serum 25(OH)D levels of these infants and their mothers were determined, and their demographic data, nutritional status, sun exposure behavior, and maternal vitamin D intake were analyzed for correlation using regression models. Results: Among the 131 infants, 101 (77%) had vitamin D deficiency (VDD), which was defined as having 25(OH)D levels <37.5 nmol/L, and 13 (10%) had vitamin D insufficiency (VDI), with levels >37.5-50 nmol/L. Conversely, maternal VDD with levels <50 nmol/L was seen in 31 (24%) mothers and maternal VDI with levels 50-75 nmol/L, in 63 (48%) mothers. Infant age and maternal 25(OH)D status were independent predictors of infant VDD. Infants less than three months old were found to have a six-time increased risk of infant VDD (p=0.004). Infants who had mothers with VDD had a six-time increased risk, whereas those with maternal VDI had a four-time increased risk of infant VDD (p=0.049 and p=0.020, respectively). Conclusion: Both infant and maternal VDD and VDI were seen to be highly prevalent in this tropical, urban community. Young infants and maternal VDD/VDI independently increased the risk of infant VDD, whereas lack of sun exposure of the mothers increased the risk for maternal VDI.

• Safety and Health at Work
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• v.12 no.1
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• pp.66-73
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• 2021

Background: The objective was to assess the knowledge level, attitude, and practice of health care workers towards standard precautions, and to identify the related factors. Furthermore, it was attempted to identify the proportion of having the experience of needle stick injuries (NSIs) and associated factors among participants. Methods: A cross-sectional study was conducted in a teaching hospital among 233 health workers using a self-administrated questionnaire. The questionnaire included eight knowledge items, seven practice items, and five attitude items. Based on the mean score of each category, responses were grouped into "satisfactory" and "unsatisfactory". Univariate, bivariate, and multivariable logistic regression analyses were done. Results: The mean age of the participants 32.95 (SD ± 9.70) and 62.2% of them were women. 57.5% of the staff had a satisfactory level of correct knowledge (>5 correct answers), 37.3% had a satisfactory positive attitude (>3 correct answers), and 30.9% had a satisfactory practice (>3 correct answers) towards standard precautions. The occupation was one of the predictors as doctors were less likely to have satisfactory knowledge and practice compared to nurses (OR = 0.269, 95% CI: 0.10-0.70 and OR = 0.248, 95% CI: 0.08-0.77, respectively). Out of 174 participants, 31.6% of them reported experiencing NSIs and support staff were 71% less likely to experience NSIs compared to nurses & paramedics. Conclusion: The findings revealed a substandard adherence of standard precautions among participants, which highlighted the necessity of the provision of a periodic, tailored training program based on the occupation and risk exposure.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.13-20
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• 2020

The effect of the relative distance between two cavity flame holders on the performance of a supersonic combustor was experimentally investigated. A rectangular cross-sectional combustor model with one cavity flame holder on each of two facing walls was used, with two difference distances between cavities of 135 mm and 220 mm. The fuel equivalence ratio was varied as 0.16 and 0.38. A direct-connected type test facility was used to provide Mach 2 flow condition. The test results revealed that the combustion pressure was higher for the shorter cavity distance case. But fuel equivalence ratio did not have large effect on the combustion pressure. It was concluded that, to get higher combustor pressure, there needs to be further combustor configuration change such as smaller cavity distance or tandem cavity installation.