• Safety and Health at Work
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• v.15 no.1
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• pp.102-109
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• 2024

Background: In today's modern world, longer working hours, shift work, and working at night have become major causes of the disruption of our natural circadian rhythms. This study aimed to investigate the effects of the type of shift work (rotating vs. fixed day), duty period (on-duty vs. off-duty), and working period within each shift (nighttime vs. daytime) on the circadian rhythm characteristics of nurses who provide direct patient care. Methods: This cross-sectional study used a purposive sampling method. Cosinor analysis was applied to analyze the actigraphy data of nurses providing direct patient care for seven consecutive days. The linear mixed effects model was then used to determine any variances between shift type, duty period, and working period within each shift for the nurses. Results: The mesor value did not differ according to nurses' shift type, duty period, and working period within each shift. The amplitude was statistically higher in on-duty nurses and in daytime working hours. The acrophase was significantly delayed in nighttime working hours. As well as nurses in rotating shift had experience. Conclusion: Our findings revealed that the peak activity of nurses occurs significantly later at night while working and nurses working during nighttime hours may have a weaker or less distinct circadian rhythm. Thus, this study suggests that limits be placed on the number of rotating nighttime shifts for nurses.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.54.1-54.1
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• 2016

Multi-wavelength variability is a staple of active galactic nuclei (AGN). Optical variability probes the nature of the central engine of AGN at smaller linear scales than conventional imaging and spectroscopic techniques. Previous studies have shown that optical variability is more prevalent at longer timescales and at shorter wavelengths. Intra-night variability can be explained through the damped random walk model but small samples and inhomogeneous data have made constraining this model hard. To understand the properties and physical mechanism of intra-night optical variability, we are performing the KMTNet Active Nuclei Variability Survey (KANVaS). Using KMTNet, we aim to study the intra-night variability of ~1000 AGN at a magnitude depth of ~19mag in R band over a total area of ${\sim}24deg^2$ on the sky. Test data in the COSMOS, XMM-LSS, and S82-2 fields was obtained over 4, 6, and 8 nights respectively during 2015, in B, V, R, and I bands. Each night was composed of 5-13 epoch with ~30 min cadence and 80-120 sec exposure times. As a pilot study, we analyzed data in the COSMOS field where we reach a magnitude depth of ~19.5 in R band (at S/N~100) with seeing varying between 1.5-2.0 arcsec. We used the Chandra-COSMOS catalog to identify 166 AGNs among 549 AGNs at B<23. We performed differential photometry between the selected AGN and nearby stars, achieving photometric uncertainty ~0.01mag. We employ various standard time-series analysis tools to identify variable AGN, including the chi-square test. Preliminarily results indicate that intra-night variability is found for ~17%, 17%, 8% and 7% of all X-ray selected AGN in the B, V, R, and I band, respectively. The majority of the identified variable AGN are classified as Type 1 AGN, with only a handful of Type 2 AGN showing evidence for variability. The work done so far confirms there are more variable AGN at shorter wavelengths and that intra-night variability most likely originates in the accretion disk of these objects. We will briefly discuss the quality of the data, challenges we encountered, solutions we employed for this work, and our updated future plans.

• Journal of Korean Academy of Nursing
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• v.15 no.3
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• pp.39-49
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• 1985

The study was carried out to measure the degree of work stress among clinical nurses, and to identify factors influencing the work stress. Data was collected from 215 staff nurses working in the Seoul National University Hospital from the end of February to first of march, 1984. The results and suggestion of study were: 1. Nurses perception of work stress. 1) Mean score of total work stress of nurses was 4.467, when maximum score was 6. High degree of work stress is evident among nurses. 2) The highest rank of stress factor was inter-personal relationship with physicians, night duty, heavy work load, inadequate working condition and payment were other stress factors. 2. Relationships between situational variables and degree of stress. There was significant correlation-ship between nurse's total work stress score and educational levels (r=0.153, p=0.032).

• Journal of the Korea Convergence Society
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• v.12 no.7
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• pp.295-304
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• 2021

This study is a secondary data analysis to investigate the nursing tasks performance, appropriate performer, and job satisfaction in the general wards with sift work. We found that nurses performed direct (45%) and indirect nursing (55%). The workload per shift was 37.2% in the day, 35.6% in the evening, and 27.2% at night. The tasks performed after handover were 'direct nursing (34.5%)' and 'documentation and notification (25.8%)'. Nurses responded that there were some tasks that could be delegated to nursing assistants or had ambiguous boundaries with other medical personnel. There was a significant correlation between compliance to the job description of the night shift and job satisfaction (rs=.43, p=.01). These results imply that it is necessary to establish strategies that will enhance work efficiency based on job analysis by shift work, reduce handover time using EMR system, stmart devices, and clarify appropriate performers.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.64.2-64.2
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• 2016

Optical variability is one way to probe the nature of the central engine of AGN at smaller linear scales and previous studies have shown that optical variability is more prevalent at longer timescales and at shorter wavelengths. Especially, intra-night variability can be explained through the damped random walk model but small samples and inhomogeneous data have made constraining this model hard. To understand the properties and physical mechanism of optical variability, we are performing the KMTNet Active Nuclei Variability Survey (KANVaS). Test data of KMTNet in the COSMOS field was obtained over 2 separate nights during 2015, in B, V, R, and I bands. Each night was composed of 5 and 9 epochs with ~30 min cadence. To find AGN in the COSMOS field, we applied multi-wavelength selection methods. Different selection methods means we are looking different region in unification model of AGN, and 100~120, 400~500, 50~100 number of AGN are detected in X-ray, mid-infrared, and radio selection of AGN, respectively. We performed image convolution to reflect seeing fluctuation, then differential photometry between the selected AGN and nearby stars to achieve photometric uncertainty ~0.01mag. We employed one of the standard time-series analysis tools to identify variable AGN, chi-square test. Preliminarily results indicate that intra-night variability is found for X-ray selected, Type1 AGN are 23.6%, 26.4%, 21.3% and 20.7% in the B, V, R, and I band, respectively. The majority of the identified variable AGN are classified as Type 1 AGN, with only a handful of Type 2 AGN showing evidence for variability. The work done so far confirms that there are type and wavelength dependence of intra-night optical variability of AGN.

• Journal of Korean Clinical Nursing Research
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• v.18 no.1
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• pp.63-73
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• 2012

Purpose: The purpose of this study was to compare job satisfaction and nursing performance of nurses on fixed night shifts (FNS) and nurses working three shifts (W3S), to identify the environment of night work and recognition of the viability of the FNS system. Methods: The research was conducted with 106 nurses on FNS and 257 on W3S. The nurses had worked for 1 to 11 years at A hospital, Seoul. Results: Job satisfaction was significantly higher (t=-3.51, p< .001) for nurses on FNS. However, no significant difference was found for nursing performance (t=-1.019, p=.309) between the two groups. Both groups of nurses were mostly satisfied. Subjective fatigue scores (0 to 10 points) during the night for nurses on FNS (6.02) were lower than for W3S nurses (7.28) A high percentage (88.7%) of nurses on FNS indicated a willingness to further participate in FNS. Conclusion: Results indicate that the demonstration FNS system showed its effectiveness. Therefore, efforts are needed to enhance and revitalize FNS and to upgrade the system to control patient transfer time from emergency departments to wards, and to provide nurses needed resources for emergency or intensive care.

• Smart Media Journal
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• v.4 no.3
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• pp.50-55
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• 2015

In this paper, we present background modeling method based on Gaussian mixture model to subtract background for night-time video surveillance. In night-time video, it is hard work to distinguish the object from the background because a background pixel is similar to a object pixel. To solve this problem, we change the pixel of input frame to more advantageous value to make the Gaussian mixture model using scaled histogram stretching in preprocessing step. Using scaled pixel value of input frame, we then exploit GMM to find the ideal background pixelwisely. In case that the pixel of next frame is not included in any Gaussian, the matching test in old GMM method ignores the information of stored background by eliminating the Gaussian distribution with low weight. Therefore we consider the stacked data by applying the difference between the old mean and new pixel intensity to new mean instead of removing the Gaussian with low weight. Some experiments demonstrate that the proposed background modeling method shows the superiority of our algorithm effectively.

• Safety and Health at Work
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• v.9 no.4
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• pp.462-467
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• 2018

Background: This study was conducted to investigate the effects of work on medical expenditures by the elderly. Methods: Data pertaining to individuals aged 65 or older collected by the Korean Health Panel 2008-2013 were used. The effects of work on medical expenditures were analyzed in a panel tobit model adjusted for several variables of demographic factors, socioeconomic factors, and health factors for health care. Data were also analyzed based on age groups (65-74, $75{\leq}$), type of work (waged or self-employed), and working time (daytime work or night time work). Results: Among the elderly older than 65 years, 34-37% were workers. Work among the elderly reduced medical expenditures relative to nonworking elderly. Specifically, medical expenditures were lower in individuals older than 75 years, as well as among those who were self-employed insured and had medical aid insurance and those who exercised. However, medical expenditures were higher among females, married individuals, those with a higher household income, and those with a chronic disease. Elderly wageworkers showed reduced medical expenditures than nonworking elderly and elderly daytime workers did. Conclusion: The elderly population's work, especially wage work and daytime work, reduced medical expenditures relative to no work. These results provide valuable information for policymakers by indicating that work was associated with lower medical expenditures than no work. If elderly work is to be encouraged, it is necessary to provide a variety of high-quality wage work.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.729-740
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• 2022

This study analyzed the effects of job stress and sleep disorders on sleepiness during the daytime for a night-shift urban railway crew. As a result of the analysis, measurements on a daytime sleepiness index were higher for the crew than those during other working hours, indicating that the degrees of sleepiness and drowsiness were severe. Afterwards, aromatic essential oils, which are generally known to help relieve sleep disorders and stress, were utilized to verify the effect on stress on night-shift workers. The experimental group treated with aromatherapy was found to show improved stress reduction and overall activity levels in the autonomic nervous system compared to an untreated control group. This study proves that night work by an urban railway crew negatively affects stress levels by increasing stress and negatively affects the autonomous nervous system, also showing that an aromatherapy treatment can be a good alternative to alleviate these conditions. The results of this study are expected to help prevent safety accidents by relieving the stress of nighttime workers.

• The Korean Journal of Health Service Management
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• v.9 no.3
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• pp.95-106
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• 2015

Objectives : The purpose of this study was to identify levels of turnover intention of nurses in long-term care hospitals, and to explore influential factors on turnover intention. Methods : Data were collected with a structured questionnaires from 165 nurses. The data were analyzed with SPSS/WIN 21.0. Results : First, the average score for the practice environment cognition, job satisfaction, reward importance, and turnover intention were $3.14{\pm}0.21$, $3.18{\pm}0.32$, $4.02{\pm}0.53$, and $3.29{\pm}0.67$, respectively. Second, there were significant differences in the turnover intention according to the average monthly wage, total clinical career, present clinical career, work form, average monthly night shift and turnover experience. Third, the significant predictors of turnover intention were monthly salary, practice environment cognition, reward importance, monthly night shift and type of work explaining 67.0%. of the variance. Conclusions : It is necessary to conduct continuous and systematic research and to find ways that can prevent the resignation of nurses and improve cognition in the practice environment in long-term hospitals nurses.