• 산업경영시스템학회지
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• 제43권2호
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• pp.39-47
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• 2020

Postural stability can reduce the likelihood of critical slip and fall accidents in workplaces. The present study aimed to analyze the effect of shoes type on the ability of postural control during quiet standing. The effect of workload on the body balance was also of primary concern. Thirteen healthy male undergraduate students participated voluntarily in the experimental study. Standing on a force plate with wearing slippers, sports shoes, or safety shoes, two-axis coordinate on subjects' center of pressures (COP) was obtained in the two levels, rest and workload. For the workload level, subjects performed treadmill exercise to reach the predetermined level of physical workload. By converting the position coordinates of COPs, the postural sway length in both anterior-posterior (AP) axis and medio-lateral (ML) axis was assessed. ANOVA results showed that, in AP direction, wearing slippers significantly increased the postural sway length compared to wearing sports shoes or safety shoes. No significant difference in the mean sway length in AP axis was observed between sports shoes and safety shoes. In ML direction, both the workload and the shoes type did not significantly affect the mean length of postural sway. However, the postural sway length increased marginally with the slippers especially during the workload condition. This study explains wearing slippers may interfere with the ability of postural control during quiet standing. Physical workload decreases the ability of postural stability further.

• Safety and Health at Work
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• 제5권3호
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• pp.152-157
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• 2014

Background: As health care workers face a wide range of psychosocial stressors, they are at a high risk of developing burnout syndrome, which in turn may affect hospital outcomes such as the quality and safety of provided care. The purpose of the present study was to investigate the moderating effect of job control on the relationship between workload and burnout. Methods: A total of 352 hospital workers from five Italian public hospitals completed a self-administered questionnaire that was used to measure exhaustion, cynicism, job control, and workload. Data were collected in 2013. Results: In contrast to previous studies, the results of this study supported the moderation effect of job control on the relationship between workload and exhaustion. Furthermore, the results found support for the sequential link from exhaustion to cynicism. Conclusion: This study showed the importance for hospital managers to carry out management practices that promote job control and provide employees with job resources, in order to reduce the burnout risk.

• 제어로봇시스템학회논문지
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• 제8권4호
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• pp.303-307
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• 2002

Virtual hosting is a typical service to connect each directory of site and domain name. If traffic amounts may increase at one site present in the server, then it affects traffic amounts of other sites as well (including the sites which have flew requests). To overcome this problem, we suggest a simple feedback-control concept for the system by periodically monitoring the traffic and properly actuating traffic dispersions by investigating the log file. Specifically, large files are to be served in a backup server (to reduce the workload of the main server) by changing their own URL's in html format. In other words, it automatically redistributes the workload by using the URL. Furthermore, we also use the redirecting method by just adding html tags to html header. This method efficiently handles the workload and maintains the capability of the server effectively to the varying workload.

• 한국항공운항학회지
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• 제17권3호
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• pp.32-39
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• 2009

Due to the lack of navigable airspace caused by worldwide air traffic increases, air traffic control(ATC) services are becoming more complex, which results in the increase of aircraft accidents. To cope with these challenges, major aviation institutes abroad are actively conducting research regarding the human factors affecting controllers but as of late, no such specialized activities have been found in Korea. Due to the dynamic attributes of ATC operations, management of controller's situation awareness(SA) and workload, and knowledge on the impact of abnormal aircraft to controllers are very important. Furthermore, using actual flight data of each country will lead to valuable results, because individually, it has different airspace characteristics and air traffic volumes. This study assumed that air traffic difficulties would affect the controller's SA and workload. To testify the above hypothesis, the abnormal air traffic situations are simulated by using ATC simulator. The findings indicated that the effect of traffic situations containing abnormal aircraft on the controller's SA and workload, it led to demand increase and supply decrease in SA, and increased mental demand, temporal demand, effort and mean workload score in the workload.

• 한국산업정보학회논문지
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• 제23권2호
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• pp.29-39
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• 2018

본 논문에서는 일량제어정책과 복수휴가정책이 혼합된 서버제어정책 하에서 운영되는 이산시간 대기행렬시스템을 다룬다. 고객들은 베르누이 도착과정으로 시스템에 도착하고, 서버는 한대가 운영되며 시스템 내 서비스할 고객이 없으면 유휴기간을 갖는 서버가 이산 확률변수 V만큼의 휴가를 떠났다가 돌아와서 대기 중인 고객들의 총 일량이 임계값 D를 넘길 때까지 휴가를 반복한다. 본 논문에서는 이산시간 시스템을 대상으로 하여 보다 현실적이며 유연한 혼합제어 정책 하에서 운영되는 대기행렬시스템의 안정상태 일량분포를 유도하고 평균일량을 계산하였다. 이는 시스템 내 고객수, 대기시간, 체재시간과 같은 시스템의 여러 성능척도를 분석하는데 기본이 된다.

• 대한산업공학회지
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• 제28권2호
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• pp.178-186
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• 2002

The objective of this study is to evaluate impact of computer-based man-machine interfaces of Korea Next Generation Reactor (KNGR) on the operator mental workload. Empirical experiments were conducted to measure the operator mental workloads of KNGR and Yong-Gwang Unit 3 and 4, respectively. A comparison analysis based on a NASA TLX revealed that Yong-Gwang Unit 3 and 4 were superior to KNGR in terms of the mental workload. Post-hoc analyses showed that the mental workload of senior reactor operators was significantly higher than those of reactor and turbine operators, regardless of plant types. The implications of the findings were discussed in detail.

• 한국산업정보학회논문지
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• 제25권1호
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• pp.89-99
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• 2020

본 논문에서는 유휴기간을 갖는 서버의 재가동이 단수휴가와 그동안 도착한 고객들의 총 일량에 의해 결정되는 이중제어정책을 다룬다. 고객들은 베르누이 도착과정으로 시스템에 한 명씩 도착하며, 자기 차례가 될 때까지 기다렸다가 선착순으로 서비스를 받는다. 서버는 시스템 내에 더 이상 서비스할 고객이 없으면 유휴기간을 가지며, 이와 동시에 이산확률변수 V의 휴가를 떠난다. 휴가 종료시점에서 대기 중인 고객들의 서비스 시간 총합이 일량 임계값 D를 초과하면 바로 서비스를 시작하고, 휴가 종료시점의 시스템 내 총 일량이 D 이하인 경우에는 일량 임계값을 넘길 때까지 기다렸다가 재가동한다. 이러한 혼합제어정책 하에서 운영되는 이산시간 Geo/G/1 대기행렬시스템을 대상으로 하여 유휴기간을 분석하고 안정상태 고객수 분포를 유도하였다.

• 전기학회논문지P
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• 제67권4호
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• pp.200-207
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• 2018

In recent, KEPCO (Korea Electric Power Corporation) faced difficulties of the DCC (distribution control center) due to the increase of field equipment and operational cost, and aging of operating staffs. In response to these changes in the DCC, KEPCO is trying to change the organization and system of the DCC. In this paper, we present a new attempt to change organization and structure of distribution control center, which was implemented by KEPCO recently. This paper is divided into three major parts. First, to examine the adequacy of the divided basis of current DCCs based on the quantity of installed electrical equipment, we analyzed the correlation between the operational history of the DCCs and the number of equipment. Through the analysis, we confirmed that there is little relationship between the number of equipment and actual workload. Second, we conducted visits and questionnaire surveys of all the DCCs to identify factors affecting the actual workload of distribution operators and then summarized the results. Third, based on this survey, a general formula for analyzing the workload of a DCC was derived, and each DCC's average annual total workload, day/night workload, and required number of personnel were calculated. Through this study, we proposed a more realistic management method of DCCs that can overcome the division criteria based on equipment quantity.

• 대한산업공학회지
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• 제26권1호
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• pp.54-65
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• 2000

The objective of this study is to evaluate the operator performance relating to hand switches with two or three buttons in the main control rooms of nuclear power plants. Based on the comparative analysis of the nuclear power plants, two different subjective workload-rating scales were used to evaluate the performance of 48 operators: the Overall Workload(OW) and National Aeronautics and Space Administration Task Load Index (NASA TLX). The survey questions consisting of the eight-items were asked to evaluate the operating experiences for the two different switch types. The OW scales ratings were applied to measure the workload of the switch-related tasks. The ratings revealed that signal detection tasks caused less workload in the three-buttoned-switch operators than the other switch group. However, in the switch operation tasks, the switch types did not show statistically significant effects on workload level. The NASA TLX scale ratings were performed based on detailed task scenarios that assumed the accident of small break loss of coolant, what we call, the small LOCH. The NASA TLX was administered to three different task groups: the reactor, the turbine, and the electric operator groups. Based on the NASA TLX, the two-buttoned switch groups showed higher workload than those with the three-buttoned switches. However, a statistically significant difference was found only in the reactor operator groups. When the current switch type was assumed to be changed for the other type, all of the three-buttoned switch groups were predicted to have higher workload than the other switch groups, respectively. The implications of these findings were discussed.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 추계학술대회논문집
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• pp.47-55
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• 1996

This study developed a comprehensive and easily applicable nuclear reactor control system evaluation method using reactor operators behavioral and mental workload database. A proposed control panel design cycle consists of the 5 steps: (1) finding out inconvenient, erroneous, and mentally stressful factors for the proposed design through evaluative experiments, (2) drafting improved design alternatives considering detective factors found out in the step (1), (3) comparative experiements for the design alternatives, (4) selecting a best design alternative, (5) returning to the step (1) and repeating the design cycle. Reactor operators behavioral and mental workload database collected from evaluative experiments in the step (1) and comparative experiments in the step (3) of the design cycle have a key roll in finding out defective factors and yielding the criteria for selection of the proposed reactor control systems. The behavioral database was designed to include the major informations about reactor operators' control behaviors: beginning time of operations, involved displays, classification of observational behaviors, dehaviors, decisions, involved control devices, classification of control behaviors, communications, emotional status, opinions for man-machine interface, and system event log. The database for mental workload scored from various physiological variables-EEG, EOG, ECG, and respir- ation pattern-was developed to indicate the most stressful situation during reactor control operations and to give hints for defective design factors. An experimental test for the evaluation method applied to the Compact Nuclear Simulator (CNS) installed in Korea Atomic Energy Research Institute (KAERI) suggested that some defective design factors of analog indicators should be improved and that automatization of power control to a target level would give relaxation to the subject operators in stressful situation.