• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.105-113
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• 2019

A construction project is a complex process consisting of interdependent tasks. If one task has variation, other tasks will be affected additionally and it is difficult to reach consensus on task variation due to the characteristics of the construction site that is going on quickly and complicatedly. Therefore, this study identified the root cause of task variation in construction process. Adjacent matrix was created with the tasks corresponding to major causes of variation, and the network analysis was performed. The results of social network analysis in the construction process can stabilize the work flow in the complex process and improve the reliability of the process plan and the project performance.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.65-70
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• 2008

Electroencephalogram(EEG) would be the most objective psychophysiological research technique on human errors though few research has been taken yet. This study aimed to get characteristics of human error while committing simple Odd-Ball tasks by utilizing the power spectrum technique of EEG data. Each experiment was composed of 3 tasks with different rules, and three young undergraduate students participated in this study as paid subjects. The result showed that subject and the interaction of subject and task factors were statistically significant on variation of power of $\alpha$ and $\beta$ bands which implied there would exist groups with homogeneity in their response. And though the variation of band powers due to task factors were not so great as to get statistical significance, it implied that the task requiring decoding process would be more strange to human beings than the task merely requiring psychological recall process.

• Journal of the Korean Society of Safety
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• v.7 no.3
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• pp.60-65
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• 1992

As many industrial workers have been involved with computer terminal tasks, for example, monitor ing, inspection, or computer da4a entry etc., concerns for difficulty evaluation of computer terminal tasks are Increased. This study provides that eyeblink can be used as a means of difficulty evaluation of a computer terminal lask. Four subjects without color blindness are asked to perform the monitoring task of the binary choice type under five levels of task difficulty. In each task, eyeblink rates and eyeblink interval times were measured from the subjects. The results show that the eyeblink rate does decrease with an Increase in task difficulty. In addition, it was found that both eyeblink interval time and eyeblink Interval time variation increased with an increase in task difficulty. It was concluded that the change of eyeblink rate, eyeblink interval time and eyeblink interval time and eyeblink interval time variation could be regarded as a generalized response to the imposition of task difficulty.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.123-130
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• 2010

Electroencephalogram(EEG) would be the most objective psychophysiological research technique on human errors though few research has been taken yet. This study aimed to get characteristics of human error while committing simple Odd-Ball tasks by utilizing the power spectrum technique of EEG data. Each experiment was composed of 3 tasks with different rules, and 8 young undergraduate students participated in this study as paid subjects. The result showed in the affirmative that subject and the interaction of subject and task factors were statistically significant on variation of $\alpha$ band power $P_{\alpha/(\alpha+\beta+\theta)}$ and $\beta$ band power $P_{\beta/(\alpha+\beta+\theta)}$, and that the former increasing in backward direction to Pz reflects compatibility whereas the latter increasing in forward direction to Fz reflects familiarity. Therefore it was coucluded that, since task 2 carried out in the present research requiring decoding process would be more difficult to human beings than the task merely requiring psychological recall process, task 1 and task 3 were classified into a homogenious group excluding task 2, and the ratio $\alpha$ band power to $\beta$ band power indicated enormous increase of $\alpha$ band power relative to $\beta$ band power in the cases of contra-lateral errors, especially in task 2.

• International journal of advanced smart convergence
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• v.11 no.3
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• pp.64-71
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• 2022

Various types of attendance management systems are being introduced in a remote working environment and research on using face recognition is in progress. To ensure accurate worker's attendance, a face recognition-based attendance management system must analyze every frame of video, but face recognition is a heavy task, the number of the task should be minimized without affecting accuracy. In this paper, we proposed a search model using time interval variation to minimize the number of face recognition task of recorded videos for attendance management system. The proposed model performs face recognition by changing the interval of the frame identification time when there is no change in the attendance status for a certain period. When a change in the face recognition status occurs, it moves in the reverse direction and performs frame checks to more accurate attendance time checking. The implementation of proposed model performed at least 4.5 times faster than all frame identification and showed at least 97% accuracy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.875-880
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• 2008

In this paper, a novel method to determine the optimal checkpoint interval for real-time control task is proposed considering its performance degradation according to tasks's execution time. The control task in this paper has a specific sampling period shorter than its deadline. Control performance is degraded as the control task execution time is prolonged across the sampling period and eventually zero when reached to the deadline. A new performance index is defined to represent the performance variation due to the extension of task execution time accompanying rollback fault recovery. The procedure to find the optimal checkpoint interval is addressed and several simulation examples are presented.

• IE interfaces
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• v.9 no.3
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• pp.269-282
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• 1996

This paper introduced a procedure for improving the quality of group decision making in various task types. Emphasis is placed on the construction of the optimal GDSS(Group Decision Support System) design with identifying the group decision characteristics of decision stages on the various task types. Especially, the identification of outliers and the establishment of confidence limits in group decision making were stressed. Participants in group decision making whose 'opinions fall outside the group's tolerance level are further studied to annex the source of this variation. The result showed that a preparation stage in the generating idea-type task and a illumination stage in the negotiating-type task were critical. Furthermore, the degree of the disagreement was severe in the verification and the preparation stages on group decision making. This paper developed a general procedure for improving the quality of group decision making. The procedure presented helps in identifying those stakeholders whose opinions may significantly deviate from that of the group.

• The Journal of Korean Physical Therapy
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• v.29 no.6
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• pp.303-306
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• 2017

Purpose: Gait variability is defined as the intrinsic fluctuations which occur during continuous gait cycles. Increased gait variability is closely associated with increased fall risk in older adults. This study investigated the influence of attention-demanding tasks on gait variability in elderly healthy adults. Methods: We recruited 15 healthy elderly adults in this study. All participants performed two cognitive tasks: a subtraction dual-task (SDT) and working memory dual-task (WMDT) during gait plus one normal gait. Using the $LEGSys^+$ system, we measured the coefficient of variation (CV %=$100{\times}$[standard deviation/mean]) for participants' stride time, stride length, and stride velocity. Results: SDT gait showed significant increment of stride time variability compared with usual gait (p<0.05), however, stride length and velocity variability did not difference between SDT gait and usual gait (p>0.05). WMDT gait showed significant increment of stride time and velocity variability compared with usual gait (p<0.05). In addition, stride time variability during WMDT gait also significantly increased compared with SDT gait (p<0.05). Conclusion: We reported that SDT and WMDT gait can induce the increment of the gait variability in elderly adults. We assume that attention demanding task based on working memory has the most influence on the interference between cognitive and gait function. Understanding the changes during dual task gait in older ages would be helpful for physical intervention strategies and improved risk assessment.

• Journal of the Korea Computer Industry Society
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• v.2 no.7
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• pp.923-932
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• 2001

In this paper, An imprecise real-time task sets composed of multimedia datas are generated using several parameters and an algorithm which can analyse schedulability of generated imprecise real-time task sets before execution of this task sets is proposed. Also, The schedulability of task set depends on variation of parameter values which were used during the generation of the task set is studied. As a result of experiment, It isproved that the schedulability of task set is more and more weak as large as execution requirement time of mandatory subtasks and, as many as the number of tasks which can be scheduled at some instant. The schedulabilty analysis algorithm which is presented on this paper is expected to use effectively on QoS service of multimedia datas.

• Journal of the Ergonomics Society of Korea
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• v.4 no.2
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• pp.11-15
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• 1985

Nowadays, there are many situations which the conventional control system can't be applied any more (e.g. nuclear waste disposal sites, radioactive laboratories, the deep ocean and the vacuum of the outer space). New control system must be considered such as supervisory control system in those environment. Using computer graphic robot simulation, supervisory control which can cope with this situation is compared to manual control. As a performance measure of these comparisons, task time and task error are used. And task difficulties and time delay are considered as a variation factor. According to the result of this study, supervisory control is superior to manual control generally. Especially in the situation including task difficulties and time delay, the superiority is much greater.