• 기본간호학회지
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• 제1권1호
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• pp.77-97
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• 1994

The circadian system represents a temporal order which is mediated by the mutual coupling of oscillators and by the synchronizing effects of zeitgebers. It is known that well-being of man depends partly on the maintenance of this order, and that repeated or long lasting disturbances to it such as shift work will Cause harmful effects. This study was a quasi-experimental study to test the effect of shift directions for the clinical nurses on the circadian rhythm. Fourteen nurses working at the general units of Y hospital were selected according to the established criteria. Fourteen subjects were assigned to a weekly shift but the directions of shift work were phase delay first and then phase advance or vice versa. Oral temperature, total sleeping time, frequency of sleep-wake cycle, fatigue, mental performance, and physical symptom were measured during these days except holidays. The data collection period was from April 26, 1993 to July 3, 1993. MANOVA and Wilcoxon signed rank test were used for statistical analysis. The results are summarized as follows. 1. Having worked on evening and night shifts in either phase delay or phase advance schedules, temperature rhythms of shift workers were gradually adapted to the new sleep-wake cycles. A complete adaptation to work on the night shift was achieved the sixth day of the night shift in the phase delay schedule compared to the partial adaptation to the work on the night shift in the phase advance schedule. Accordingly, by putting evening shift between day and night shifts, it will be possible for circadian rhythm to adapt easily to the night shift. 2. There were differences in the total sleeping time, frequency of steep-wake cycle, fatigue, and physical symptom except for mental performance between night shift and day, evening shift. This indicates further that shift workers working on the night shift have a hard time adapting to the shift work compared to the other shifts. 3. Evaluating all the acrophases of temperature rhythm either in phase delay or phase ad-vance schedules, it was shown that night to evening shift in the phase ad-vance schedule revealed the smallest phase move. Also phase advance schedule showed poorer adaptation to shift work than phase delay schedule in connection with total sleeping time, frequency of sleep-wake cycle, fatigue, mental performance, and physical symptom. It is suggested, taken together, these findings reflect that phase delay schedule facilitated the degree of adjustment to the shift work compared to the phase advance schedule.

• 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.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.187-190
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• 2003

Many manufacturing companies consider the integrated and concurrent scheduling because they need the global optimization technology that could manufacture various products more responsive to customer needs. In this paper, we propose an advanced scheduling model to generate the schedules considering resource constraints and precedence constraints in make-to-order (MTO) manufacturing environments. Precedence of work- in-process(WIP) and resources constraints have recently emerged as one of the main constraints in advanced scheduling problems. The advanced scheduling problems is formulated as a multiobjective mathematical model for generating operation schedules which are obeyed resources constraints, alternative workstations of operations and the precedence constraints of WIP in MTO manufacturing. For effectively solving the advanced scheduling problem, the multi-objective hybrid genetic algorithm (m-hGA) is proposed in this paper. The m-hGA is to minimize the makespan, total flow time of order, and maximum tardiness for each order, simultaneously. The m-hGA approach with local search-based mutation through swap mutation is developed to solve the advanced scheduling problem. Numerical example is tested and presented for advanced scheduling problems with various orders to describe the performance of the proposed m-hGA.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.329-337
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• 2016

With the increasing deployment of distributed generators in the distribution system, a very large search space is required when dynamic programming (DP) is applied for the optimized dispatch schedules of voltage and reactive power controllers such as on-load tap changers, distributed generators, and shunt capacitors. This study proposes a new optimal voltage and reactive power scheduling method based on dynamic programming with a heuristic searching space reduction approach to reduce the computational burden. This algorithm is designed to determine optimum dispatch schedules based on power system day-ahead scheduling, with new control objectives that consider the reduction of active power losses and maintain the receiving power factor. In this work, to reduce the computational burden, an advanced voltage sensitivity index (AVSI) is adopted to reduce the number of load-flow calculations by estimating bus voltages. Moreover, the accumulated switching operation number up to the current stage is applied prior to the load-flow calculation module. The computational burden can be greatly reduced by using dynamic programming. Case studies were conducted using the IEEE 30-bus test systems and the simulation results indicate that the proposed method is more effective in terms of saving electric charges and improving the voltage profile than loss minimization.

• 한국항해항만학회지
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• 제33권6호
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• pp.429-436
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• 2009

컨테이너터미널에서 사용되는 컨테이너 크레인은 컨테이너 선박의 컨테이너를 양적하하는 주요 장비이다. 크레인이 고장이 나면, 컨테이너터미널의 생산성을 감소시킬 것이다. 본 논문은 컨테이너 크레인에 대한 예방정비 일정을 다룬다. 컨테이너 크레인은 많은 부품으로 구성되고 3개의 모델을 사용하여 컨테이너 크레인의 구조를 분석한다. 그리고 최적의 예방정비 일정을 결정하기 위하여 유전자 알고리즘을 적용하고 시뮬레이션 시스템을 통해서 제안된 방법의 성능을 평가한다. 마지막으로 작업일정에 기초하여 산업체에서 발견된 예방정비 일정을 조정하는 방법을 설명한다.

• 한국건축시공학회지
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• 제10권2호
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• pp.51-57
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• 2010

건설공사의 일정관리는 주어진 기간 내에 프로젝트를 완수하기 위한 중요한 수단이다. 액티비티의 수가 많아지고 복잡한 선후행 관계가 형성될수록 일정관리 소프트웨어를 활용해야 하는 필요성이 증대되고 있다. 또한 정보통신기술이 발달하면서 웹기반의 프로젝트관리 기술과 도구도 발전하고 있고 다수의 프로그램도 개발되어 있다. 본 연구는 웹 기반에서 일정관리 도구를 개발하기 위해 상호작용성이 우수한 플래시를 이용하는 방법을 제안하였다. 제안된 방법을 구현하기 위해 플래시와 액션스크립트로 프로토타입을 작성하였고 웹 화면에서 공정표를 표현하여 적용성을 검토하였다.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.975-983
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• 2022

This paper presents an innovative way of integrating scheduling and project controls with the environmental impact of a construction project to track, monitor, and manage environmental emissions at the activity level. As a starting point, scheduling and project controls help monitor the status of a project to provide an assessment of the duration and sequence of activities. Additionally, project schedules can also reflect resource allocation and costs associated with various phases of a construction project. Owners, contractors and construction managers closely monitor tasks or activities on the critical path(s) and/or longest path(s) calculated through network based scheduling techniques. However, existing industry practices do not take into account environmental impact associated with each activity during the life cycle of a project. Although the environmental impact of a project may be tracked in various ways, that tracking is not tied to the project schedule and, as such, generally is not updated when schedules are revised. In this research, a Cradle to Gate approach is used to estimate environmental emissions associated with each activity of a sample project schedule. The research group has also investigated the potential determination of scenarios of lowest environmental emissions, just as project managers currently determine scenarios with lowest cost or time. This methodology can be scaled up for future work to develop a library of unit emissions associated with commonly used construction materials and equipment. This will be helpful for project owners, contractors, and construction managers to monitor, manage, and reduce the carbon footprint associated with various projects.

• 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.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.336-338
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• 2015

This research is to propose an applicable framework for real-time health surveillance and safety monitoring at construction sites. First this study aims at finding (1) a framework for health surveillance that is likely to benefit employers and employees in the industry, (2) a valid way to identify factors or conditions with potential health concerns that can occur under particular work conditions, (3) An effective way to apply wireless/mobile sensors to construction workers using real-time/live data transmission methods, and (4) A relationship between a worker's vital signs and job site environment. Biosensors for physiological response and devices for weather/work related data are to collect real-time data. Relationships between jobs and physiological responses are analyzed and factors that touched particularly contributing to certain responses are identified. When data are incorporated with tasks, factors affecting tasks can be identified to estimate the magnitude of the factors. By comparing work and normal responses possible precautionary actions can be considered. In addition, the study would be lead to improving (1) trade-specific dynamic work schedules for workers which would be based on various factors affecting worker health level and (2) reevaluating worker productivity with health status and work schedule, thereby seeking ways to maximize worker productivity. Through a study, the paper presents expected benefits of implementing health monitoring.

• 벤처혁신연구
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• 제6권3호
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• pp.185-202
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• 2023

코로나19팬데믹을 기점으로 근무방식의 전면적인 변화와 직장 유연성에 대한 필요성이 대두되고 있다. 종업원들이 근무장소와 근무시간을 유연하게 사용할 수 있는 다양한 근무제도에 대한 연구가 많은 반면 보다 넒은 의미에서의 직장 유연성에 대한 연구는 중요성에 비해 부족한 편이다. 이러한 문제인식하에 본 연구는 정보통신 서비스 산업과 제조 산업의 외국계 기업과 국내 상위 50개 대기업에 근무하는 종업원 300명을 대상으로 직장 유연성이 조직몰입에 미치는 영향을 실증적으로 분석해 보고자 했다. 직장 유연성을 양적 직장 유연성과 질적 직장 유연성으로 구분하여 연구 변수를 설정하였다. 실증 분석 결과는 다음과 같다. 양적 직장 유연성의 유형 중 근무 장소, 근무 연속성과 질적 직장 유연성을 의미하는 업무 자율성과 팀워크의 경우 조직몰입에 유의미한 정(+)의 영향을 미치는 것으로 나타났다. 반면 양적 직장 유연성 유형 중 근무 시간의 경우 조직몰입에 유의미한 영향을 미치지 못하는 것으로 나타났다. 한편 질적 직장 유연성이 양적 직장 유연성에 비해 조직 몰입도 미치는 영향이 강하다는 것을 확인했다. 이러한 연구 결과는 학술적으로는 직장 유연성을 양적인 측면과 질적인 측면을 동시에 고려했다는 점이다. 실무적으로는 질적 직장 유연성 확보를 위해 업무 자율성과 팀워크를 제고할 수 있는 다양한 영역에서 종업원간의 열린 의사소통 및 협업을 촉진할 필요가 있을 것이다. 또한 서로 피드백을 주고받을 수 있는 커뮤니케이션을 촉진하는 조직 분위기 및 업무 환경 조성의 필요성을 제시했다.