Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Kim IJ[original query] |
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Correlation Between Third Dose of COVID-19 Vaccines and Regional Case Fatality Rates During the Omicron Wave in Korea.
Jang Y , Kim IJ , Moon SS , Kim SB , Lee J . J Korean Med Sci 2022 37 (50) e347 This study seeks to find the correlation between case fatality rates (CFRs) and third-dose vaccination coverage in 244 counties (si/gun/gu) of South Korea during the omicron variant wave. Multivariate regression analyses report that the higher third-dose vaccination rates were correlated with lower regional CFRs, when controlling for age structure. If the third-dose vaccination rate of a county is higher by 10%, it would have a CFR lower by 0.05% (95% confidence interval, 0.03-0.08%). As the number of cumulative confirmed cases in South Korea was 16,353,495 as of April 20, 2022, a lower CFR by 0.03-0.08% is equivalent to 4,394-12,448 lives (8.6-24.4 per 100,000) spared. County-specific characteristics, such as age structure, intensive care unit availability, and the level of non-pharmaceutical interventions may also affect the extent of this correlation. The conclusion implicates the potential role of coronavirus disease 2019 vaccines in reducing the pressure on the regional healthcare capacity. |
Research to improve extension ladder angular positioning
Simeonov P , Hsiao H , Powers J , Kim IJ , Kau TY , Weaver D . Appl Ergon 2012 44 (3) 496-502 A leading cause for extension ladder fall incidents is a slide-out event usually related to suboptimal ladder inclination. An improved ladder positioning method or procedure could reduce the risk of ladder stability failure and the related fall injury. The objective of the study was to comparatively evaluate the effectiveness of a multimodal angle indicator with other existing methods for extension ladder angular positioning. Twenty experienced and 20 inexperienced ladder users participated in the study. Four ladder positioning methods were tested in a controlled laboratory environment with 4.88 m (16 ft) and 7.32 m (24 ft) ladders in extended and retracted positions. The positioning methods included a no-instruction method, the current standard anthropometric method, and two instrumental methods - a bubble level indicator, and a multimodal indicator providing direct feedback with visual and sound signals. Performance measures included positioning angle and time. The results indicated that the anthropometric method was effective in improving the extension ladder positioning angle (p < 0.001); however, it was associated with considerable variability and required 50% more time than no-instruction. The bubble level indicator was an accurate positioning method (with very low variability), but required more than double the time of the no-instruction method (p < 0.001). The multimodal indicator improved the ladder angle setting as compared to the no-instruction and anthropometry methods (p < 0.001) and required the least time for ladder positioning among the tested methods (p < 0.001). An indicator with direct multimodal feedback is a viable approach for quick and accurate ladder positioning. The main advantage of the new multimodal method is that it provides continuous feedback on the angle of the device and hence does not require repositioning of the ladder. Furthermore, this indicator can be a valuable tool for training ladder users to correctly apply the current ANSI A14 standard anthropometric method in ladder angular positioning. The multimodal indicator concept has been further developed to become a hand-held tool in the form of a smart phone application. |
Factors affecting extension ladder angular positioning
Simeonov P , Hsiao H , Kim IJ , Powers JR , Kau TY . Hum Factors 2012 54 (3) 334-45 OBJECTIVE: The study objectives were to identify factors affecting extension ladders' angular positioning and evaluate the effectiveness of two anthropometric positioning methods. BACKGROUND: A leading cause for extension ladder fall incidents is a slide-out event, usually related to suboptimal ladder inclination. An improved ladder positioning method or procedure could reduce the risk of ladder stability failure and the related fall injury. METHOD: Participants in the study were 20 experienced and 20 inexperienced ladder users. A series of ladder positioning tests was performed in a laboratory environment with 4.88-m (16-ft) and 7.32-m (24-ft) ladders in extended and retracted positions. The setup methods included a no-instruction condition and two anthropometric approaches: the American National Standards Institute A14 and "fireman" methods. Performance measures included positioning angle and time. RESULTS: The results indicated that ladder setup method and ladder effective length, defined by size and extended state, affected ladder positioning angle. On average, both anthropometric methods were effective in improving extension ladder positioning; however, they required 50% more time than did the no-instruction condition and had a 9.5% probability of setting the ladder at a less-than-70 degrees angle. Shorter ladders were consistently positioned at shallower angles. CONCLUSION: Anthropometric methods may lead to safer ladder positioning than does no instruction when accurately and correctly performed. Workers tended to underperform as compared with their theoretical anthropometric estimates. Specific training or use of an assistive device may be needed to improve ladder users' performance. APPLICATION: The results provide practical insights for employers and workers to correctly set up extension ladders. |
Functional levels of floor surface roughness for the prevention of slips and falls: clean-and-dry and soapsuds-covered wet surfaces
Kim IJ , Hsiao H , Simeonov P . Appl Ergon 2012 44 (1) 58-64 Literature has shown a general trend that slip resistance performance improves with floor surface roughness. However, whether slip resistance properties are linearly correlated with surface topographies of the floors or what roughness levels are required for effective slip resistance performance still remain to be answered. This pilot study aimed to investigate slip resistance properties and identify functional levels of floor surface roughness for practical design applications in reducing the risk of slip and fall incidents. A theory model was proposed to characterize functional levels of surface roughness of floor surfaces by introducing a new concept of three distinctive zones. A series of dynamic friction tests were conducted using 3 shoes and 9 floor specimens under clean-and-dry as well as soapsuds-covered slippery wet environments. The results showed that all the tested floor-shoe combinations provided sufficient slip resistances performance under the clean-and-dry condition. A significant effect of floor type (surface roughness) on dynamic friction coefficient (DFC) was found in the soapsuds-covered wet condition. As compared to the surface roughness effects, the shoe-type effects were relatively small. Under the soapsuds-covered wet condition, floors with 50 mum in Ra roughness scale seemed to represent an upper bound in the functional range of floor surface roughness for slip resistance because further increase of surface roughness provided no additional benefit. A lower bound of the functional range for slip resistance under the soapsuds-covered wet condition was estimated from the requirement of DFC > 0.4 at Ra congruent with 17 mum. Findings from this study may have potential safety implications in the floor surface design for reducing slip and fall hazards. |
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