• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.161-170
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• 1999

This paper evaluates forty different dispatching rules with respect to twenty different performance measures of job shop scheduling under seven levels of workload imbalance. Computer simulation is used as a tool to determine rankings of the dispatching rules for a given workload imbalance. The experiments results show rankings of dispatching rules are different in the job shop with unbalanced machine workloads. As variations of workload imbalance increase from 7% to 78%, the performance of dispatching rules is gradually deteriorated in measure related to completion time and due date. These results guide scheduling practitioners not only to choosing dispatching rules but also to developing the model of facility investment for workload balance, when there are different levels of workload imbalance.

• IE interfaces
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• v.25 no.2
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• pp.196-203
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• 2012

In the postal delivery service, both the standardization of business process and the workload measurement is very important part of saving the cost and improving the efficiency. However, these are not easy to apply to real situation because of the labor-intensive and diversification of delivery environment. In this study, we develop the methodology for the standardization of business process and workload measurement model of the postal delivery service. Firstly, we introduce the work factor analysis on the postal delivery process. Then, we propose the methodology workload measurement model based on diversification of delivery environment.

• IE interfaces
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• v.25 no.2
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• pp.187-195
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• 2012

The driver model based on the ACT-R cognitive architecture was developed in order to predict the performance and cognitive workload of a driver operating HVI devices. In the 10 HVI tasks, the predicted performance time and cognitive workload by the ACT-R driver model was well matched and highly correlated with the mean of performance times and subjective workload ratings from 15 participants, respectively. It is strongly proposed that the ACT-R driver model in this study can be applied to evaluate the usability of a new HVI design with less cost in the early stage of system development.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.45
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• pp.145-154
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• 1998

The effects of secondary task on driving performance and subjective workload were investigated during a simulated driving. The driving performance was determined by the appropriateness of break timing. The driving simulator was provided by the Korea Road Traffic Safety Association. The subjective workload was tested by using a multidimensional measure such as NASA-TLX. Road was categorized into two types: narrow alley and wide street. The secondary task included pushing the number on the cellular phone, pushing radio channel, and conversing with a passenger. Seventeen subjects volunteered in the study. The data were analyzed by using SAS. Results showed that using the cellular phone and pushing channel during driving caused 3∼22% decline of driving performance and 42∼59% increase of subjective workload respectively. These results indicated that the secondary task could be potentially dangerous although there was not a significant performance decrease due to the notable increase of mental workload. In the future, if we can use a more sensitive and realistic driving simulator, the effects of secondary task under a dynamic driving situation can be investigated.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.25-34
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• 2009

A cross-sectional study was conducted to assess the association between musculoskeletal workload and psychosocial job stress variables from 100 employees from a cable making industry. It was found that the employees who had to do musculoskeletal hazardous tasks suffered higher psychosocial stress in 'decision latitude', 'job insecurity' and 'psychological job demands' also. The employees with higher level of psychosocial job stress in 'psychological job demands' and 'score of the "type A" personality' responded that they had higher 'physical job demands' from the task irrespective of its musculoskeletal hazardousness. These results confirm that musculoskeletal workload were associated with both physical and psychosocial work factors. Attention should be paid to psychosocial work factors along with physical workload to prevent musculoskeletal disorders in the manufacturing industries.

• Journal of the Ergonomics Society of Korea
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• v.18 no.2
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• pp.103-120
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• 1999

The purpose of this study was to evaluate the manual workload in repetitive wrist and finger motion. To evaluate manual workload, angular displacement of the joint, EMG of the muscle and subjective rating were studied. Both wrist motion and finger motion were studied. A screw-driving task was used for the wrist motion experiment. A keyboard typing task was used for the finger motion experiment. All finger joint angles and wrist angles were measured by an angle-measuring glove($CyberGlove^{TM}$, Virtual Technologies, Inc.). Surface EMG was recorded from FCU muscle and FDS muscle simultaneously with the angle measurement. Subjective ratings of exertion were also recorded using the modified Borg's CR-10 scale. Repetition rates of 0.5, 1, 2 motions per second were used with each task. As a result, manual workload increased with increasing repetitiveness. Peak spectral magnitude and frequency components corresponded closely with joint angular displacement amplitudes and repetition rates. Results of the correlation analysis showed that there were significant correlation among EMG, frequency-weighted motion and subjective measurement. Both EMG and frequency-weighted filtering showed consistent workload estimation with increasing task frequency. Subjective ratings showed slight over-estimation of the workload as the task frequency is increased.

• Nutrition Research and Practice
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• v.5 no.1
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• pp.80-87
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• 2011

The objectives of the study were to investigate job burnout and leader-member exchange (LMX) levels as well as to evaluate buffering effects of LMX on burnout among dietitians and chefs at institutional foodservices. Hypotheses were proposed based on the Job Demands-Resources model and LMX theory. The study population consisted of dietitians and chefs who were in charge of managing unit operations in a nationwide contract management company. Positive/negative affectivity, workload, job burnout, and LMX scales that bad been validated in previous research were adopted A total of 552 questionnaires were distributed and 154 responses were returned. Results indicated that respondents' burnout levels were moderate and emotional exhaustion was greater than cynicism. In terms of LMX, the surveyed dietitians and chefs showed higher respect toward their supervisors than loyalty. When positive affectivity and negative affectivity were controlled, workload influenced emotional exhaustion and professional efficacy significantly. With affectivity and workload controlled, however, LMX did not influence any dimensions of burnout. The moderating effect of LMX on the relationship between workload and cynicism was significant. That is, the effect of workload on cynicism was weak if the dietitians and chefs perceived the relationship with their supervisor positively. Based on the findings and literature reviewed, how to mitigate job burnout among foodservice managers is discussed.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.6
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• pp.1440-1458
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• 2013

The purpose of this study was to explore teachers' workload and its sources from teachers' perspective. Toward the purpose, interviews with and essays written by teachers were analyzed to interpret the meaning of teachers' workload and examine the relationship between their workload and social forces. The results indicated that teachers' workload could be fully understood when amount, intensity and nature of teachers' work were considered together. Among them the nature of work centered on non-educational affairs was perceived most serious problem by the teachers. However, most of the teachers felt helpless at their situation largely made by socio-structural factors including neoliberalism, bureaucracy and authoritarianism. Such a submissive reaction of teachers interacted with the forces to contribute to sustain their predicament.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.139-145
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• 2017

PURPOSES : This study analyzed the difference in a driver's workload between using a driving simulator and field driving in tunnel, highway. METHODS : Based on the literature review, it was found that a driver's workload could be quantified using biosignals. This study analyzed the biosignal data of 30 participants using data collected while they were using a driving simulator and during a field test involving tunnel driving. Relative energy parameter was used for biosignal analysis. RESULTS : The driver's workload was different between the driving simulator and field driving in tunnels, highway. Compared with the driving simulator test, the driver's workload exhibited high value in field driving. This result was significant at the 0.05 level. The same result was observed before the tunnel entrance section and 200 m after the entrance section. CONCLUSIONS : This study demonstrates the driving simulator effect that drivers feel safer and more comfortable using a driving simulator than during a field test. Future studies should be designed considering the result of this study, age, type of simulator, study site and so on.

• Journal of the Ergonomics Society of Korea
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• v.32 no.5
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• pp.475-480
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• 2013

Objective: In this study, virtual reality was adopted to consider ergonomic factors in yacht design. Virtual human which is the same actual human was created in virtual environment using Digital Human Modeling which has been used in the manufacturing communities to design better workplaces and maximize the safety of workers. Background: During the past 40 years yachting has expanded from being, generally speaking, a minority sport - too expensive for the large majority of people - into a major recreational activity practiced by millions all over the world. Many new yacht designs have appeared and number of professional, as well as amateur designers has increased steadily. But they had not considered ergonomic factors in yacht design. Method: Worker's posture, traffic line and workload had been analyzed in sailing yacht. After the caution level was evaluated, we pointed out clues which had high workload and interference. To reduce workload, we applied ergonomic principles for improving working conditions and environments in Digital Human Model. Results: We found the space problems and workload of postures. Conclusion: (1) Unnatural posture of crews was sustained. (2) Workload that occurs in the human body was overloaded. (3) Crew's work space was very narrow. Application: This study will be applied the new ergonomic design of yacht.