• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.273-277
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• 2002

In this paper, with martingale argument we derive the explicit formula for the Laplace transform of the busy period of M/M/1 queue with bounded workload which is also called finite dam. Much simpler derivation than appeared in former literature provided.

• Science of Emotion and Sensibility
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• v.4 no.1
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• pp.1-5
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• 2001

The evaluation of mental workload is measured by subjective ratings, physiological signals. It takes long time to analysis the measured signals and is very tedious and time-consumming work. Therefore, to evaluate the affect of workload effectively, real-time measurement system is required. In this paper, real-time mental workload measurement system using cardiac autonomic indiced which reflect well the mental workload was developed and evaluated. Analyzed indices were HR, IBI, Lorentz plot, CSI, CVI, and LF/HF ratio of heart rate variability. The system was applied to evaluate the affect of arithmetic task and showed good results. This system was consisted of ECG amplifier, A/D converter, and personal computer, and algorithm was implemented using LabVIEW.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.2
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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.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.66-70
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• 2013

This study examined the relative effects of education and eco-IVIS(in-vehicle information system) to reduce fuel consumption and greenhouse gas emissions. Also the study investigated the increasing of driving workload when drivers interact with intervention technique. Thirty participants randomly assigned into two groups(training and eco-IVIS) and conducted driving before and after the each intervention technique. While driving, we observed three driving behaviors: Frequency of excessive RPM, percent of speeding, and mean fuel efficiency. Also the Driver Activity Load Index was used to rate participants' subjective ratings of driving workload. Although the results showed positive impact of both education and eco-IVIS to increasing the eco-driving behaviors, eco-IVIS was more effective than education. However, we found comparable level of driving workload in the education and eco-IVIS.

• IE interfaces
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• v.16 no.2
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• pp.222-228
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• 2003

Computer-dominated jobs and industrial automation have rapidly created work-related musculoskeletal disorders(WMSDs) and WMSDs are also founded in employees of other general industries. WMSDs has been growing problems for Korean industries with higher incidence rate every year. The objective of this paper is to analyze the effects of the neck muscle workload according to postures(joint angle) and load weights. Seven male students participated in this study. Neck workload was rated on each person using a Borg's CR-10 scale. ANOVA showed that the CR-10 ratings were statistically significant according to postures and load weights. To reduce the large number and severity of WMSDs, which employees have been experiencing, we need to redesign the job in workplace so that we can control hazards that are reasonably likely to be causing or contributing to the WMSDs. The results of this study can be used to establish the safety criteria of joint angle and weight of neck workload.

• Korean Management Science Review
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• v.12 no.1
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• pp.51-60
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• 1995

This paper presents a workload based model and cell design support system (CDSS) in manufacturing cell design. The proposed model consider manufacturing factor such as machine capacity, production volume, process time, and cell size. Based on those information, workload is calculated and according to the workload, the relationship between machine and part is represented by the workload matrix. To form the manufacturing cell, correlation similarity coefficient (CSC) among machines are calculated and a pair of machines that has the highest value of CSC is assigned to a machine cell. Repeat the above steps until the desired manufacturing cells are obtained. Finally, a cell design support system that could increase the efficiency in the application of a proposed model is developed. The proposed model and CDSS are illustrated by a numerical example.

• Communications of the Korean Mathematical Society
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• v.28 no.2
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• pp.383-396
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• 2013

We consider an M/PH/1 queue with deterministic impatience time. An exact analytical expression for the stationary distribution of the workload is derived. By modifying the workload process and using Markovian structure of the phase-type distribution for service times, we are able to construct a new Markov process. The stationary distribution of the new Markov process allows us to find the stationary distribution of the workload. By using the stationary distribution of the workload, we obtain performance measures such as the loss probability, the waiting time distribution and the queue size distribution.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.241-242
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• 2017

미국 해안경비대 및 영국 해양사고조사국에 의하면 해양사고에서 인적과실의 원인중 상당부분 선원 피로에 기인하는 것으로 조사되었으며, 스웨덴에서의 연구 결과 약 73% 정도 선박 당직근무자들이 당직 근무 시간 중 최소 1회 또는 그 이상 졸음에 빠져 있는 것으로 보고하고 있다. 본 연구에서는 국내 연안선 항해당직자들을 대상으로 Workload를 분석하였으며, 효율적으로 Workload를 측정할 수 있는 방안을 제시하였다.

• Journal of the Ergonomics Society of Korea
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• v.29 no.4
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• pp.445-453
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• 2010

It is necessary to quantitatively evaluate the workload of workers in order to improve the level of safety and efficiency as well as to prevent workers from musculoskeletal disorders. The purpose of this study is to introduce biomechanical methods that are largely used to quantitatively evaluate workload. The biomechanical methods use kinematics and kinetics to analyze the movement and force of biomechanical body. Motion analysis, joint angle measurement, ground reaction force, mathematical model, and electromyography (EMG) were introduced as a tool or device for biomechanical evaluation. In this study, the special feature of each method was emphasized and important tips for field measurement were summarized. The information and technique disclosed in this summary can be used to evaluate and design the workplace better by effectively control the workload of field workers.

• Journal of Biomedical Engineering Research
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• v.32 no.4
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• pp.328-335
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• 2011

For human factor engineering and wearable robot design, the quantitative assessment of physical workload is needed. Through measuring the surface EMG (sEMG) and analysis, the physical workload in overhead lifting posture is presented in quantitative manner. By normalizing sEMG activities with maximal voluntary contraction (MVC), the inter-subject variability is reduced. In all muscles, %MVC increased as the weight of lifting object increases. In anterior deltoid muscle, the %MVC was 3-4 times higher than the other muscles which imply that this muscle performs the major role in the overhead lifting posture. In fatigue analysis, %MVC and the mean frequency in muscle of anterior deltoid changed markedly when compared with other muscles. Through the suggested procedures and analysis, the physical workload for a specific posture can be represented in quantitative way but the clinical meaning for the value should be investigated further.