• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1864-1873
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• 2018

Energy shifting is an innovative method used to obtain the highest profit from the operation of energy storage systems (ESS) by controlling the charge and discharge schedules according to the electricity prices in a given period. Therefore, in this study, we propose an optimal charge and discharge scheduling method that performs energy shift operations derived from an ESS efficiency model. The efficiency model reflects the construction of power conversion systems (PCSs) and lithium battery systems (LBSs) according to the rated discharge time of a MWh-scale ESS. The PCS model was based on measurement data from a real system, whereas for the LBS, we used a circuit model that is appropriate for the MWh scale. In addition, this paper presents the application of a genetic algorithm to obtain the optimal charge and discharge schedules. This development represents a novel evolutionary computation method and aims to find an optimal solution that does not modify the total energy volume for the scheduling process. This optimal charge and discharge scheduling method was verified by various case studies, while the model was used to realize a higher profit than that realized using other scheduling methods.

• 대한인간공학회지
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• 제22권3호
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• pp.13-26
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• 2003

The purpose of this study is to investigate the present conditions of the night work and shift work systems in the heavy chemical industrial complexes found in Changwon, Masan, and Chinhae. Korea. We will attempt to define and classify their problems; and to discover further ways to improve their systems. Fifty production factories were carefully selected as the subjects for this study. The shift systems were classified into five categories. The consecutive night shifts were long in almost all cases with 6 days (36 factories) and 7 days (13 factories). It was found that the night work of about] 2 hours continues for a long period in the weekly rotation full-day shift systems and the night-including non-full-day shift systems, and there was no holiday during a shift cycle in the continuous full-day shift systems. The work time in most shift systems was longer than the 44-hours/week permitted by Korean law. Considering the characteristics of these various types of shift systems, the most essential thing to reduce the shift workers' work load may be to shorten their working hours and improve the schedule of shift systems. It is highly recommended as a fundamental solution. to reduce the portal-to-portal hours from 12 to 8 in the night-including non-full-day shift systems and the weekly rotation full-day shift systems, and at least to employ a 4-team 3-shift system in the continuous full-day shift systems. In addition to this, it should from now on be taken as a goal to restructure the types of shift systems by taking such measures as avoiding continuous night work if possible, providing sufficient off-duty intervals both before and after night shift, providing increased opportunities for workers to nap during night work. and increasing the number of holidays.

• 대한간호학회지
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• 제21권2호
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• pp.129-149
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• 1991

Circadian rhythm is entrained in the 24-hour time interval by periodic factors in the environment, known as zeitgeber. But most rotating work schedules are outside the range of the entrainment of the pacemaker timing the human circadian sleep - wake cycle. It has been postulated that physiological and emotional disturbances occur in most human functions when the circadian rhythm is disturbed. So application of circadian principles to the design of shift schedules can aid in maintaining the temporal integrity of the circadian system and thereby minimize for the shift worker any detrimental consequences of circadian disruption. This study was a quasi-experimental study to test the effect of shift intervals for the clinical nurse on the circadian rhythm. Twenty nurses newly employed in general units of two hospitals were selected as an experimental group and twelve college nursing students as a control group. Both groups were selected according to an established criteria using a purposive sampling technique. Ten subjects were assigned to a weekly shift group and another ten to a biweekly shift group engaged in a semi -continuous shift schedule(sunday off) with a backward direction, that is, morning -evening - night shift. The control group worked a morning shift for 42 days. Oral temperature rhythm, waking tim, sleep - wake cycle, fatigue, and mental performance were measured during the experimental period. The data collection period was from April 30, 1990 to June 10, 1990. MANOVA, paired t-test, ANOVA, and Student Newman Keuls method were used for statistical analysis. The results are summarized as follows. 1. Phase delay in the acrophase of temperature rhythm was shown according to the backward rotating shift. A complete adaptation to work on the night shift was achieved between the sixth and ninth day of the night shift. 2. There was no difference in either waking time or sleep- wake cycle according to the duration of the working day for every shift group. Significant difference was found in the waking time and the sleep -wake cycle for subjects on the morning, evening, and night shift in both of the shift groups(weekly shift group : λ＝0.121, p＜0.01, λ＝0.112, p＜0.01, biweekly shift group : λ＝0.116, p＜0.01, λ＝0.084, p＜0.01). 3. There was no difference in fatigue between the first working day and the last working day for the control group and for the biweekly shift group. In the weekly shift group, physical fatigue was significantly different for the first day and the sixth day of the night shift(t＝-2.28, p＜0.05). Physical fatigue and total fatigue on the first day of the night shift showed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝5.79, p＜0.01, F＝4.56, p＜0.05). There was a significant difference between the shift groups and the control group(p＜0.05), Physical fatigue, neurosensory fatigue and total fatigue on the last day of the night shift showed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝12.65, p＜0.01, F＝7.77, p＜0.01, F＝9.68, p＜0.01). There was a significant difference between the shift groups and the control group(p＜0.05). 4. No difference in mental performance was seen between the first day and the last day of work in each case. An arithmatic test on the first day of the night shift revealed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝3.79, p＜0.05). There was a significant difference between the shift groups and the control group(p＜0.05) . The digital symbol substitution test and the arithmetic test on the last day of the night shift showed a significant difference among the control group, the weekly shift group, and the biweekly shift group(F＝3.68, p＜0.05, F＝5.55, p＜0.01), and both showed a significant difference between the shift groups and the control group(p＜0.05). Accordingly, this study showed that during night duty, the waking time, sleep- wake cycle, and fatigue increased and mental performance decreased compared with morning and evening duty. It was also found that the weekly shift group had a higher fatigue score on the sixth day of night duty as compared to the -first day, but the waking time, sleep- wake cycle, and mental performance revealed no difference for the duration of the night duty or between shift groups, and complete adaptation of temperature rhythm was achieved between the sixth and ninth day of night duty. It is possible to conclude from these results that for intermediate circadian type in a healthy young woman, a biweekly shift system is more compatible with the circadian timing system than weekly shift system.

• 한국항공운항학회지
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• 제32권1호
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• pp.91-102
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• 2024

This study aimed to investigate the sleep-wake patterns, social jetlag (SJL), and daytime sleepiness (DS) among air traffic controllers (ATCs) with rotating shifts. A total of 133 shift-rotating ATCs participated by completing self-report questionnaires regarding their sleep-wake patterns and DS. SJL, indicating the mid-sleep difference between workdays (W) and free days (F), was calculated for each shift. Night-shift workdays had the shortest sleep duration (SD) (5.28 hours), whereas free days following day shifts had the longest SD (6.66 hours). SJL for day and night shifts was 2.73 and 2.71 hours, respectively. The average DS score was 7.92 out of 24, with a 28.6% prevalence of DS. There was a negative correlation between SD following day shifts and SJL for the day shifts. Given these findings, it is recommended to implement effective interventions and work schedules to maintain consistent sleep patterns and minimize social jetlag to address sleep issues for shift-working ATCs.

• 임상간호연구
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• 제29권3호
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• pp.223-237
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• 2023

Purpose: This study aimed to investigate the impact of a nurse shift improvement pilot project on nurses' shift adjustment, work-life balance, and turnover intention, as well as nurses' experiences of participating in the pilot project. Methods: An explanatory sequential mixed-methods study was performed. Survey data was collected from a total of 1,051 nurses both in participant and non-participant groups. For the qualitative study, focus group interviews were conducted with 22 nurses who participated in the shift improvement pilot, including 12 staff nurses, 7 nurse managers, and 3 substitute nurses. Results: There were significant positive effects on the key variables of nurses' shift adjustment, work-life balance, and turnover intention in the group that participated in the nurse shift improvement pilot project. Based on the qualitative study, participants in the shift improvement pilot project indicated that it enabled nurses to recover their circadian rhythm, and achieve a better work-life balance, and they wanted to continue working as a nurse, and hoped expanded application of the pilot project. Conclusion: In order for expanded implementation of the pilot project and continued improvement in the shift system, we recommend establishing compensation standard, systematizing the use of substitute nurses, developing guidelines for shift schedules, and expanding the shift improvement pilot project to other departments such as the emergency room.

• 한방안이비인후피부과학회지
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• 제19권3호통권31호
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• pp.180-188
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• 2006

Objectives : The purpose of this study is to investigate the differences of skin disease, particularly Acne between the rotating shift work nurses and the nurses on a fixed day schedule. Methods : Questionnaries were distributed to 30 rotating shift work nurses(the rotating group) and 34 nurses on a fixed day schedule(the daytime group). The questionnaris included questions on general health concepts, insomnia skin disease(particularly Acne), gastroenteric trouble, menstrual irregularity. Result : 1. There was significant difference on skin disease(particularly Acne) between two groups. 2. There was no significant relation between Gastroenteric trouble and Acne. But, in particular, there was significant relation between Constipation, Gastritis and Acne. 3. There was no significant relation between menstrual irregularity and Acne. 4. In Acne group, more than 70% felt the necessity of treatment, but only 2.5% used Korean Oriental Medical therapy. Conclusion : Disorder of circadian rhythm affects the skin disease(particularly Acne) more than Gastroenteric trouble and menstrual irregularity. But in this study, the total number of the nurse is not enough. So we need more accurate study about the aspects of skin disease. And about the Acne, publicity of Korean Oriental Medical therapy is required.

• Safety and Health at Work
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• 제1권2호
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• pp.112-123
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• 2010

The paper gives an overview of the problems to be tackled nowadays by occupational health with regards to shift work as well as the main guidelines at organizational and medical levels on how to protect workers' health and well-being. Working time organization is becoming a key factor on account of new technologies, market globalization, economic competition, and extension of social services to general populations, all of which involve more and more people in continuous assistance and control of work processes over the 24 hours in a day. The large increase of epidemiological and clinical studies on this issue document the severity of this risk factor on human health and well being, at both social and psychophysical levels, starting from a disruption of biological circadian rhythms and sleep/wake cycle and ending in several psychosomatic troubles and disorders, likely also including cancer, and extending to impairment of performance efficiency as well as family and social life. Appropriate interventions on the organization of shift schedules according to ergonomic criteria and careful health surveillance and social support for shift workers are important preventive and corrective measures that allow people to keep working without significant health impairment.

• Journal of Preventive Medicine and Public Health
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• 제25권4호
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• pp.374-385
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• 1992

교대근무자들이 호소하는 생체리듬의 부조화로 인한 일련의 증상들은 개인특성, 작업환경, 교대형태의 영향을 많이 받는다. 따라서 본 연구에서는 개인특성과 작업환경의 영향을 고려하여 교대주기에 따른 근로자들의 자각증상의 차이를 보고자, 작업환경이 같고 교대주기에 있어 2일, 7일인 두 회사의 3교대근로자 182명과 86명을 대상으로 개인 특성 및 자각증상을 설문조사하였다. 결과를 요약하면 다음과 같다. 1. 수면장해증상 6문항 중 '근무 중 피로감을 느낀다', '예민하다'의 두 항목에서 7일주기의 교대근무자에서 증상호소의 빈도가 통계적으로 유의하게 높았으며(P<0.05), 점수화하여 두 군간의 평균을 비교한 결과 7일주기인 군에서 증상점수가 높았다(P<0.01). 2. 1일 평균 6시간의 수면을 기준으로 할 때, 수면시간에 있어서는 두 군간에 유의한 차이가 없었으며, 2일주기인 군에서는 수면시간이 증가함에 따라 장해증상에 현저히 줄었으나 (P<0.05), 7일주기인 군에서는 수면시간에 따른 장해증상의 차이가 없었다. 3. 소화기장해증상 10문항에서는, 7일주기인 군에서 '자주 그렇다'고 호소하는 빈도가 높았으나 통계적인 유의성은 없었으며, 점수화하여 두 군간의 평균을 비교한 결과 역시 7일 주기인 군이 평균점수가 높았으나 통계적으로 유의한 차이는 아니었다. 4. 피로자각증상은 육체적, 정신적 피로 호소율이 7일주기의 교대근무자들에게 현저히 높았으며(P<0.01), 신경감각적 피로 역시 유의한 차이가 있었다(P<0.05). 5. 공분산분석 (ANCOVA)을 통해 개인특성의 영향을 고려한 결과, 교대주기에 파라 수면장해 증상, 육체적, 정신적 피로에 통계적으로 유의한 차이를 보였다(P<0.01). 이상의 결과를 종합해 볼때, 2일주기의 교대근무자들보다 7일주기 교대근무자들이 피로와 수면장해증상 호소가 더 많았다. 따라서 향후 자각증상 뿐 아니라 객관적인 검사를 병행하여 현재 가장 많이 시행되고 있는 7일주기의 교대제에 대한 검토가 필요할 것으로 사료된다.

• Safety and Health at Work
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• 제5권2호
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• pp.73-79
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• 2014

Background: The aim of this study was to investigate the burden experienced by nursing personnel working irregular shifts in Greece and to conduct the first test of a Greek version of the Standard Shiftwork Index (SSI). Methods: A cross-sectional survey was carried out. The SSI was completed by 365 nurses and nursing assistants working shifts, including nights. Results: Female nursing personnel and those suffering from a chronic disease were most affected by working rotating shifts as they had elevated scores on the majority of the SSI scales, such as sleep, chronic fatigue, digestive and cardiovascular problems, general health questionnaire, cognitive and somatic anxiety, shift time satisfaction, engagement and disengagement strategies, languidity, flexibility, and neurotisicm. Nurses with longer working experience and those with family responsibilities also scored higher on some of the SSI scales, such as the sleep, shift time satisfaction, social and domestic disruption, disengagement strategies, morningness, and languidity scales. Conclusion: Shiftwork affects female nurses, those with chronic disease, older age, and domestic responsibilities more severely. Therefore management should take these factors into account when designing work schedules to alleviate the burden caused by shiftwork.

• 수면정신생리
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• 제26권2호
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• pp.111-124
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• 2019

목 적 : 건강한 수면은 중요하며 회복탄력성에 긍정적인 영향을 줄 수 있다. 본 연구에서는 교대근무 간호사와 주간 고정 근무 간호사 두 집단에서 회복탄력성의 차이를 비교하고 회복탄력성에 영향을 줄 수 있는 요인들을 조사해보고자 하였다. 방 법 : 두 개의 종합병원에 근무하는 만 20세 이상의 여성 교대근무 간호사와 주간고정근무 간호사 400명을 대상으로 하였으며 2017년 6월 12일부터 2018년 6월 12일까지 설문조사하였다. 한글판 스트레스 자각척도, 스트레스 대처전략 축약형, 사회심리적 건강측정도구, 한국판 역학연구센터 우울척도, 상태불안척도, 피츠버그 수면의 질 지수, 엡워스 주간졸음 척도, 불면증 심각도 척도, 코너 데이비슨 리질리언스 척도 질문지를 적용하였다. 결 과 : 교대근무간호사와 고정근무간호사 두 집단 간의 변수 통계량을 비교한 결과 스트레스 자각, 수면의 질, 주간 졸음증을 제외한 모든 변수에서 통계적으로 의미 있는 차이를 나타내었다. 회복탄력성과 유의한 상관을 보인 요소들은 근무자들의 스트레스 대처전략, 사회 심리적 건강수준, 우울증, 불면증 심각도 이었다(p < 0.05). 다중회귀분석에서는 긍정적 재구성1이 커질수록(β = 0.206, p < 0.001), 우울증이 줄어들수록(β = -3.45, p < 0.001), 사회심리적 건강수준이 높아질수록(β = 0.193, p < 0.001), 수용적 대처2가 증가할수록(β = 0.129, p < 0.05), 주간졸음이 줄어들수록(β = -1.17, p < 0.05), 적극적 대처2가 증가할수록(β = 0.118, p < 0.05), 긍정적 재구성2가 증가할수록(β = 0.110, p < 0.05) 회복탄력성이 커지는 것으로 나타났다. 결 론 : 본 연구에서는 교대근무자에 비해 주간고정 근무자의 회복탄력성이 높음을 밝힐 수 있었다. 또한 특정 스트레스 대처 전략과 사회심리적 건강수준, 수면, 우울증이 회복탄력성과 연관이 있는 것으로 확인되었다. 향후 더 많은 수면과 회복탄력성과의 관계를 밝히는 전향적 연구들이 필요할 것으로 생각된다.