• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.66-73
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• 2020

The change in labor consciousness began to draw social attention to work-life balance (WLB). The WLB is one of the major factors affecting the health and safety problems of workers. Although shiftwork adversely affects WLB, safety, and health problems of workers, WLB of shift workers has received little empirical attention. The purpose of this study was to examine whether WLB mediates the relationship between shiftwork and shift worker's safety and health problems, participation in leisure activities moderates WLB, and finally, whether WLB moderated by participation in leisure activities mediates the relationship between shift work and shift worker's safety and health problems. For the study, the data of the 5^th wave of Korean Working Condition Survey(KWCS) conducted by Korea Occupational Safety and Health Agency(KOSHA) of South Korea was used. Conditional process analysis revealed that the relationship between shift work and worker's safety and health problems is mediated by WLB; however, participation in leisure activity showed no moderation effect on WLB. Therefore, the moderated mediation effect has failed to achieve statistical significance. The results indicate that working environment improvement in consideration of the WLB is needed to gain shift worker's long-term safety and health. The implications of this study and suggestions for future research were discussed.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.89-96
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• 1986

The NMR chemical shift arising from 4d electron angular momentum and 4d electron spin dipolar-nuclear spin angular momentum interaction for a $4d^1$ system in a strong crystal field of octahedral symmetry, when the threefold axis is chosen as the quantization axis, has been investigated. A general expression using a nonmultipole expansion method is derived for the NMR chemical shift. From this expression all the multipolar terms are determined. We find that the nonmultipolar results for the NMR chemical shift ${\Delta}B$, is exactly in agreement with the multipolar results when $R {\ge} 0.20$ nm. It is also found that the 1/$R^7$ term contributes to the NMR chemical shift almost the same as the 1/$R^5$ in magnitude. The temperature dependence analysis of ${\Delta}B$/B(ppm) at various values of R shows that the 1/$T^2$ term has the dominant contribution to the NMR chemical shift but the contributions of other two terms are certainly significant for a $4d^1$ system in a strong crystal field of octahedral symmetry when the threefold axis is chosen to be the axis of quantization.

• Journal of Korean Academy of Nursing
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• v.54 no.2
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• pp.139-150
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• 2024

Purpose: This study aimed to identify changes in sleep patterns and fatigue levels during consecutive night shifts among shift nurses and to determine the association between sleep parameters and increased fatigue levels during work. Methods: This prospective observational study employing ecological momentary assessments was conducted using data collected from 98 shift nurses working in Korean hospitals between June 2019 and February 2021. The sleep patterns were recorded using actigraphy. The participants reported their fatigue levels at the beginning and end of each night shift in real time via a mobile link. Linear mixed models were used for the analysis. Results: Nurses spent significantly less time in bed and had shorter sleep durations during consecutive night shifts than on off-duty days, whereas their wake times after sleep onset were much longer on off-duty days than on on-duty days. Fatigue levels were higher on the second and third night-shift days than on the first night-shift days. A shorter time spent in bed and asleep was associated with a greater increase in fatigue levels at the end of the shift than at the beginning. Conclusion: Nurses experience significant sleep deprivation during consecutive night shifts compared with off-duty days, and this sleep shortage is associated with a considerable increase in fatigue levels at the end of shifts. Nurse managers and administrators must ensure sufficient intershift recovery time during consecutive night shifts to increase the time spent in bed and sleeping.

• Korean Journal of Occupational Health Nursing
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• v.33 no.3
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• pp.109-116
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• 2024

Purpose: This study aimed to identify the influence of work-life balance and insomnia severity on shift working nurses' health promotion behaviors. Methods: Participants were 152 nurses who worked rotating shifts at a general hospital. Data were collected from August 2 to 16, 2023 and analyzed by t-test, ANOVA, Pearson correlation, and multiple regression analysis using SPSS/WIN 25.0. Results: The participants exhibited high insomnia severity and low scores in both work-life balance and health promotion behaviors. Health promotion behaviors were positively correlated with work-life balance but negatively correlated with insomnia severity. The key factors influencing shift-working nurses' health promotion behaviors included work-life balance (β=.37, p<.001) and gender (female) (β=-.17, p=.026), with an explanatoty power of 18% (F=12.35, p<.001). Conclusion: Work-life balance is a significant variable affecting shift-working nurses' health promotion behaviors. The health of nurses is crucial not only for their personal well-being but also for ensuring the patient safety. Therefore, flexible work systems and adaptable health program schedules must be implemented to promote the health of shift-working nurses.

• Journal of Home Health Care Nursing
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• v.31 no.2
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• pp.166-176
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• 2024

Purpose: This study examined the effects of parenting stress, social support, and job satisfaction on job embeddedness of in shift working married nurses. Methods: The participants were 131 nurses in five general hospitals. Data collection was conducted using self-report questionnaires from Aug 1 to 16, 2023. Data were analyzed using descriptive statistics, independent t-test, One-way ANOVA, Pearson correlation coefficients and multiple regression analysis. Results: There were not significant differences in job embeddedness by general characteristic. The job embeddedness of in shift work nurses were significant correlation parenting stress, social support, and job satisfaction. The factors influencing on job embeddedness of the shift work nurses were job satisfaction. It was found that 61% could explain job embeddedness. Conclusion: It is necessary to nurse' support strategies for improving job satisfaction, and need to develop of program to relieve parenting stress, and strengthen social support to enhance job embeddedness of the shift work nurses.

• Journal of Technology Innovation
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• v.28 no.2
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• pp.1-36
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• 2020

While the policy intervention of each country for the promotion of renewable energy is strengthened, Korea introduced Feed-in Tariff (FIT) in 2002 to directly support the development of renewable energy. But in 2012, the shift of policy instrument that from FIT to Renewable Portfolio Standard (RPS) is occurred. This is a unique background that is currently found only in Korea, and new answers that focus on the outcomes of the shift of policy instruments are needed in addition to the existing discussion of comparison of FIT and RPS. Therefore, this study analyzed the change of policy efficiency after the shift to RPS using Data Envelopment Analysis(DEA) and Malmquist Index. In the result of analysis, a difference in the improvement of policy efficiency after in shift to RPS is found among each renewable energy source. This result is because renewable energy companies voluntarily entered the market only for energy sources that have secured technology or price competitiveness, and this indicates that the performance of renewable energy after the RPS shift has been concentrated on specific energy sources. As a result of this study, considering that the goal of renewable energy policy is to expand distribution and to drive growth engines, multi-faceted analysis is required in consideration of technology and market in selecting policy instruments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4B
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• pp.355-362
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• 2006

Several techniques of MK test, Spearman's Rho test, Linear Regression test, CUSUM test, Cumulative Deviation, Worsley Likelihood Ratio test, Rank Sum test, and Students' t test were applied to detect the trends of slope and shift which exist in hydrologic and climate time series. The time series of annual rainfall, inflow, tree ring index, and southern oscillation index (SOI) were used and the trends of these series were compared in the study. From the results, it can be found that the data could be classified into two categories such as linear trend and shift. 4 series data of 8 rainfall series which reveal the trend show the shift and 8 series data of 18 tree ring index and March and April series of monthly SOI data show shift. Moreover, ADF test and BDS test were used to test stationarity and non-linearity of the data. In conclusion, through the study, various trend analysis techniques were compared and 6 kinds of characteristics which can exist in hydrologic time series were identified.

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.182-189
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• 2004

Objectives : The objective of this study is to compare the circadian patterns of heart rate variability assessed by 24-hour ambulatory electrocardiographic (ECG) recordings during day shift and night shift among the workers in the 5 days-concecutive-12-hour shift in an automobile factory in Korea. Methods : The study population consisted 300 workers, who were randomly selected among the 8700 total workers in one car factory. To analyse circadian variation, the 24-hour ECG recordings (Marquette) were measured during day shift (08:00-20:00 h) and night shift (20:00-08:00 h). Analysis was performed for all time and frequency domain measures of HRV. 233 workers completed taking 24-hour ECG recordings. Results : This study shows that the 24 hourcircadian variation mainly follows work/sleep cycle rather than day/night cycle among shift workers. This study also shows that among the night shift, the circadian variation between work and sleep cycle decreased compared to the work/sleep cycle among day shift workers. All time and frequency domain parameters (except LF/HF ratio) show significantly different between work and sleep in the day shift and night shift. Conclusion : These changes in heart rate variability circadian rhythms reflect significant reductions in cardiac parasympathetic activity with the most marked reduction in normal vagal activity among the shift workers. Especially, it suggests the circadian rhytm has blunted among the night workers. The quantification of the circadian variation in HRV can be a surrogates of workers' potential health risk, as well as suggests possible mechanisms through which the shift works compromise workers' health.

• Journal of Navigation and Port Research
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• v.35 no.10
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• pp.811-816
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• 2011

In this paper, we analysis to consider the performance of PSPM (Phase Shift Pulse-position Modulation), the one of the low power communication technique, in near-field underwater sound channel by sea trial. PSPM is a QPSK(Quadrature Phase Shift Keying) modulation combined with PPM(Pulse Position Modulation) for low power communication in WBAN(Wireless Body Area Network). It is known that the bandwidth efficiency of PSPM is lower than conventional PSK but the power efficiency increases. In this paper, we will analyze the BER performance of PSPM using data acquired from the sea trials. The BER of QPSK was $6.04{\times}10^{-2}$, PSPM was $3.5{\times}10^{-1}$. Also, PSNR of QPSK was 9.37 dB and in case of PSPM was 9.11 dB.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.36.1-36.12
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• 2022

Background: Many studies have been conducted to investigate the harmful effect of shift work on physical and mental health. Although, by definition, "working evening shift" is included in the scope of shift work, most related studies conducted thus far have focused on working night shifts, overtime work, or different types of shift work, with little research effort dedicated to "working evening shifts." Therefore, to fill this research gap, we investigated the effect of working evening shifts on workers' mental health. Methods: The participants of this study were 16,692 employees of the 50,205 that participated in the 5th wave of the Korean Working Conditions Survey. We performed χ² test and logistic regression analysis to analyze the effects of independent variables on health problems and calculated odds ratios and 95% confidence intervals (CIs). Results: In the logistic regression analysis adjusted for sociodemographic characteristics, health-related factors, and work-related characteristics, employees who worked evening shifts showed higher levels of depression and anxiety compared to those that did not. In particular, the adjusted odds ratios of the group working evening shifts between one and nine times a month were the highest with 2.723 (95% CI: 2.014-3.682) for depression, 3.294 (95% CI: 2.547-4.259) for anxiety. Conclusions: The results of our study suggest that working evening shifts has a negative effect on employees' mental health. This trend decreased with an increase in the monthly frequency of evening work.