• Safety and Health at Work
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• 제15권1호
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• pp.53-58
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• 2024

Background: As social distancing persists and interest in work-life balance grows, more companies are adopting flexible work policies. While there have been studies on sleep disorders associated with different types of work, such as shift work, research exploring the relationship between flexible work schedules and sleep disorders is still limited, particularly among Korean workers. Methods: We performed a secondary analysis of the 6th Korean Working Conditions Survey, focusing on 31,243 paid workers out of a total of 50,538 participants. We defined flexible workers as those who set their own working hours. Sleep disorders were divided into three categories: 'difficulty falling asleep,' 'frequent waking during sleep,' and 'waking up feeling exhausted and fatigued.' Using scores derived from three specific symptoms, the Minimal Insomnia Symptoms Scale (MISS) was calculated to assess the prevalence of insomnia. We used chi-square tests to analyze demographic and job-related differences. A multivariate logistic regression analysis was employed to identify any relationship between flexible work schedules and sleep disorders. Results: Significant differences were found between flexible and non-flexible workers regarding age, income level, education level, and job type. Flexible workers reported sleep-related symptoms significantly more often. The odds ratio for insomnia was 1.40 (95% CI 1.21-1.61). For males, the odds ratio was 1.68 (1.36-2.08). Conclusion: This study establishes a correlation between flexible work schedules and sleep disorders among Korean salaried workers. Potential causes could include changes in circadian rhythm, increased work demands, and extended working hours. To precisely determine causality and associated diseases, further research is required.

• Safety and Health at Work
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• 제12권3호
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• pp.390-395
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• 2021

Background: Health-care providers typically undergo shift work and are subjected to increased stress. Night shift work may induce disturbed sleep cycles and circadian rhythm. The objective of this study was to explore if night shift workers (NSWs) show an increased risk of abnormal thyroid-stimulating hormone (TSH). Methods: We conducted a retrospective cohort study of 574 employees without thyroid disease and abnormal TSH at baseline who underwent annual check-ups between 2007 and 2016 in a medical center. NSWs were defined as those with working time schedules other than daytime hours. We calculated the incidence rate and estimated the adjusted hazard ratio (HR) for incident abnormal TSH and subclinical hypothyroidism compared with non-NSWs using a Cox regression model. Results: A total of 56 incident abnormal TSH cases and 39 subclinical hypothyroidism cases in NSWs were identified during 3000 person-years of follow-up. In models adjusted for age, sex, obesity, and working departments, we found no increased relative risk for incident abnormal TSH (HR: 0.72, 95% confidence interval: 0.33-1.60) or subclinical hypothyroidism (HR: 0.52, 95% confidence interval: 0.19-1.45) when comparing NSWs to non-NSWs; nor were incidence rates significantly different among exclusively medical employees after excluding administrative staff. Conclusion: In this hospital-based nine-year follow-up retrospective cohort study, NSWs were not associated with increased relative risk of incident abnormal TSH and subclinical hypothyroidism, in contrast to previous cross-sectional studies.

• Safety and Health at Work
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• 제7권2호
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• pp.111-119
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• 2016

Background: Shift work and/or sleep quality may affect health. We investigated whether shift work and sleep quality, separately and jointly, were associated with abnormal levels of triglycerides, total cholesterol (TC), and low-and high-density lipoprotein cholesterol in 360 police officers (27.5% women). Methods: Triglycerides, TC, and high-density lipoprotein were analyzed on the Abbott Architect; low-density lipoprotein was calculated. Shift work was assessed using City of Buffalo payroll work history records. Sleep quality (good, ${\leq}5$; intermediate, 6-8; poor, ${\geq}9$) was assessed using the Pittsburgh Sleep Quality Index questionnaire. A shift work + sleep quality variable was created: day plus good sleep; day plus poor sleep; afternoon/night plus good; and poor sleep quality. Mean values of lipid biomarkers were compared across categories of the exposures using analysis of variance/analysis of covariance. Results: Shift work was not significantly associated with lipids. However, as sleep quality worsened, mean levels of triglycerides and TC gradually increased but only among female officers (age- and race-adjusted p = 0.013 and 0.030, respectively). Age significantly modified the association between sleep quality and TC. Among officers ${\geq}40$ years old, those reporting poor sleep quality had a significantly higher mean level of TC ($202.9{\pm}3.7mg/dL$) compared with those reporting good sleep quality ($190.6{\pm}4.0mg/dL$) (gender- and race-adjusted p = 0.010). Female officers who worked the day shift and also reported good sleep quality had the lowest mean level of TC compared with women in the other three categories (p = 0.014). Conclusion: Sleep quality and its combined influence with shift work may play a role in the alteration of some lipid measures.

• 한국발생생물학회지:발생과생식
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• 제16권1호
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• pp.53-58
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• 2012

Circadian rhythmicity (e.g. secretory pattern of hormones) plays an important role in the control of reproductive function. We hypothesized that the alteration of feeding pattern via meal time shift/restriction might disrupt circadian rhythms in energy balance, and induce changes in reproductive activities. To test this hypothesis, we employed simple animal model that not allowing $ad$ $libitum$ feeding but daytime only feeding. The animals of $ad$ $libitum$ feeding group (Control) have free access to food for 4 weeks. The day feeding (=reverse feeding, RF) animals (RF group) have restricted access to food during daytime (0900-1800) for 4 weeks. After completing the feeding schedules, body weights, testis and epididymis weights of animals from both group were not significantly different. However, the weights of seminal vesicle (control : RF group = $0.233{\pm}0.014g$ : $0.188{\pm}0.009g$, $p$<0.01) and prostate (control : RF group = $0.358{\pm}0.015g$ : $0.259{\pm}0.015g$, $p$<0.001) were significantly lower in RF group animals. The mRNA levels of pituitary common alpha subunit ($C{\alpha}$; control : RF group = $1.0{\pm}0.0699$ AU : $0.1923{\pm}0.0270$ AU, $p$<0.001) and $FSH{\beta}$ (control : RF group = $1.0{\pm}0.1489$ AU : $0.5237{\pm}0.1088$ AU, $p$<0.05) were significantly decreased in RF group. The mRNA levels of ACTH were not significantly different. We were unable to find any prominent difference in the microstructures of epididymis, and there were slight alterations in those of seminal vesicles after 4 weeks of reversed feeding when compared to control samples. The present study demonstrates that the shift and/or restriction of feeding time could alter the pituitary gonadotropin expression and the weights of seminal vesicle and prostate in rats. These data suggest the lowered gonadotropin inputs may decrease androgen secretion form testis, and consequently results in poor response of androgen-dependent tissues such as seminal vesicle and prostate.

• Safety and Health at Work
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• 제8권1호
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• pp.29-35
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• 2017

Background: Despite our knowledge of the causes of cancer, millions of workers are involuntarily exposed to a wide range of known and suspected carcinogens in the workplace. To address this issue from a policy perspective, we developed a policy framework based on a prospective health policy analysis. Use of the framework was demonstrated for developing policies to prevent cancers associated with diesel engine exhaust (DEE), asbestos, and shift work, three occupational carcinogens with global reach and large cancer impact. Methods: An environmental scan of existing prospective health policy analyses was conducted to select and describe our framework parameters. These parameters were augmented by considerations unique to occupational cancer. Policy-related resources, predominantly from Canada, were used to demonstrate how the framework can be applied to cancers associated with DEE, asbestos, and shift work. Results: The parameters of the framework were: problem statement, context, jurisdictional evidence, primary prevention policy options, and key policy players and their attributes. Applying the framework to the three selected carcinogens illustrated multiple avenues for primary prevention, including establishing an occupational exposure limit for DEE, banning asbestos, and improving shift schedules. The framework emphasized the need for leadership by employers and government. Conclusion: To our knowledge, this is the first proposal for a comprehensive policy framework dedicated to the primary prevention of occupational cancer. The framework can be adapted and applied by key policy players in Canada and other countries as a guide of what parameters to consider when developing policies to protect workers' health.

• Industrial Engineering and Management Systems
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• 제6권1호
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• pp.22-27
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• 2007

This paper describes the optimization of maintenance workforce scheduling at Afam power station in Nigeria. The objective is to determine the optimum schedule to satisfy growing maintenance labour requirements with minimum cost and highest efficiency. Three alternative maintenance workforce schedules are compared. The first alternative is to continue with the traditional five-day workweek schedule currently being practiced by Afam power station maintenance line. The second alternative is to switch to a seven-day workweek schedule for the morning shift only. The third alternative is to use a seven-day workweek schedule for all three work shifts. The third alternative is chosen, as it is expected to save 11% of the maintenance labour cost.

• 정신신체의학
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• 제29권2호
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• pp.111-120
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• 2021

연구목적 이전 연구에 따르면 교대근무는 인간의 자연적인 일주기 리듬에 적응하기 어렵게 만들어 각종 건강문제를 일으킨다. 특히 교대근무자는 근무 일정과 연관된 수면의 어려움을 호소하는 경향이 있으며, 알코올을 수면유도를 위한 자가약으로 사용하는 경우가 있다. 현재까지 교대근무와 수면 및 음주와의 관련성에 관한 명확한 기전이 밝혀지지 않고 있는 상태이다. 따라서 이 연구에서는 교대근무와 수면과의 관련성을 확인하고, 교대근무로 인한 수면의 변화가 음주를 유발하는지에 대해 분석하고자 한다. 방 법 이 연구는 국민건강영양조사 제6기, 제7기 자료 중 2014, 2016, 2018년도를 분석대상으로 하였으며 총 11360명(남성 5704명, 여성 5656명)을 연구대상인원으로 포함시켰다. 6 am-6 pm사이의 근무형태를 주간근무, 이외의 근무형태를 교대근무로 정의하였으며 로지스틱 회귀분석을 통하여 교대근무와 수면의 질, 교대근무와 고위험 음주, 음주량 및 음주 횟수의 관계를 분석하였다. 또한 매개분석을 통하여 수면이 교대근무와 음주의 관계를 매개하는지 여부를 분석하였다. 결 과 교대근무는 남성과 여성에서 수면 질과 유의한 음의 관계를 보였다(남성 OR=1.37, 95% CI=1.11-1.70, 여성 OR=1.26, 95% CI=1.05-1.50). 교대근무와 음주와의 관계에서는 남성의 경우 유의한 관계가 나타나지 않았으나, 여성의 경우 교대근무와 음주횟수에서 유의한 양의 관계를 보였다(OR=1.34, 95% CI=1.04-1.72). 매개분석 시행 시 여성의 수면 질은 교대근무와 음주횟수의 관계를 부분매개하는 것으로 나타났다. 결 론 이 연구의 결과는 교대근무가 수면의 어려움을 유발하며, 여성의 경우에서는 수면의 부분매개효과를 통해 음주를 유발할 수 있음을 시사한다. 여성이 수면장애에 대한 대처방안으로 음주를 선택할 가능성이 높은 점을 고려할 때, 여성 교대근무자에 대한 보다 적극적인 중재방안이 마련된 필요가 있다.

• 한국컴퓨터정보학회논문지
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• 제25권3호
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• pp.57-64
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• 2020

오늘날 정보 기술의 발전으로 병원은 의료분야에서 모바일 컴퓨팅 기술을 접목하여 의료 정보의 방대한 데이터를 관리를 위해서 시간과 공간의 제약을 받지 않는 병원정보시스템을 활발하게 연구하고 있다. 그럼에도 불구하고 대부분의 병원에서는 여전히 수작업으로 근무 편성표를 작성하는데 많은 노력과 시간을 소요하고 있다. 이에 본 논문은 간호사의 교대 근무를 편성하는 최적화 모델을 연구하고 이를 적용한 간호사 니즈형 근무 편성 자동화 시스템을 구축하였다. 실제 S병원에 근무하는 간호사를 대상으로 간호사의 정보 데이터와 요구조건 및 제약조건들을 구성하였다. 이를 적용하여 최적화된 스케줄링 처리 방법을 제안하였고 웹 서버를 중심으로 실시간 상호 교환 및 공유가 가능하기 위해서 수간호사가 사용하는 웹 기반 플랫폼과 일반 간호사가 사용하는 모바일 앱 플랫폼을 구축하였다. 따라서 개발된 간호사 니즈형 근무 편성 자동화 시스템을 통해서 수간호사는 매월 간호사의 근무 편성을 위한 업무 편리성을 증가시켜 주며, 간호사는 개인 일정관리를 통해서 좀 더 정확하게 업무를 처리할 수 있도록 도움을 줄 것이다. 또한 간호사간의 근무 일정의 공유하여 업무의 효율성이 증가할 것으로 기대한다.

• Korean Chemical Engineering Research
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• 제43권5호
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• pp.571-578
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• 2005

불연속 화학공정은 소비자 수요에 탄력성 있게 대처할 수 있는 장점이 있는 반면에 그 특유의 동특성 때문에 복잡하고, 계획된 조업 시간과 실제 조업 시간 사이에서 외란(disruption) 또는 불확실 변수(uncertainty)에 의한 차이가 자주 발생하는 단점이 있다. 이에, 본 논문에서는 예측 생산계획(predictive scheduling)에 의해 결정된 생산계획에서 미래에 발생하는 공정 변수 값의 변화를 실시간으로 예측 생산계획을 수정, 제시하여 주는 생산 계획 시스템인 동적 생산계획(reactive scheduling) 기법을 개발하였다. 불확실 인자를 고려한 동적 생산계획에서, 본 논문에서는 장치 이상(equipment failure)이 발생하였을 때 공정 운전조건의 변화를 실시간으로 반영하여, 예측 생산계획(predictive scheduling) 모델에 의하여 제시된 전체 생산 계획을 최대한 유지하고 공정 변수의 변화를 실시간으로 반영하기 위하여 right shift rescheduling과 total regeneration 기법을 사용하였다. 또한, 불확실 인자의 발생 전후의 predictive scheduling과 reactive scheduling 간의 변화 정도를 측정하는 수단인 schedule stability 위하여, 본 논문에서는 수정된 sequence deviation과 percentage change in makespan을 사용하여 제안된 동적 생산계획의 안정성을 측정하였다. 본 논문에서 제안한 동적 생산계획 시스템은 기존에 제시되었던 경험 법칙에 의한 결과값에 비해 좋은 결과를 보여주었다.

• 대한인간공학회지
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• 제24권2호
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• pp.57-63
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• 2005

Ergonomic intervention techniques were adopted to assess and control potential risk factors of work-related musculoskeletal disorders(WMSDs) in the automated light assembly manufacturing system. Ten different kinds of assembly workstations implemented with a conveyor system and twelve female workers were observed and evaluated with careful video film analysis. Several close examinations using sets of checklists established by qualified safety and health organizations, such as NIOSH, OSHA, and ANSI, were conducted and every workers and staffs in the site participated in the self-report questionnaires and off-line interviews. Typical risk factors and symptoms of the upper extremity musculoskeletal disorders were found and categorized into specific parts of body. To reduce risk factors of WMSDs and improve system productivity new revised workstation standards, physical dimensions, were suggested accordant with anthropometric characteristics of workers and a heuristic decision strategy of rotating shift work schedules according to work contents has proposed to mitigate cumulative physical stress. Finally, ergonomic programs of entire company to prevent WMSDs were structured.