• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.69-75
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• 2009

It is well-known that lifting capacity of a worker is influenced by body posture during the task. When a task analyst make use of RULA and REBA Trunk and upper arm angles are recorded in a separate item. It means that the interaction between the angles of two body segments may be ignored in a final score. The NLE(NIOSH Lifting Equation) has been used to supplement this problem. However, there is no study to validate the result of RWL (Recommended Workload Limit) under the existence of interactions between trunk and upper arm angles. The goal of this study was to assess the effect of the interaction between trunk and upper arm angles. Three responses, including NMVC(normalized maximum voluntary contraction), RWL(Recommended Weight Limit) and subjective judgment in psychophysical method (Borg's scale), were recorded according to the combinations of three trunk angles and nine upper arm angles. The results showed that lifting capacity is highly influenced by interaction of two body segments(trunk and upper arm). It means that the task workload has to be analyzed along with the interaction of trunk angles and upper arm angles when the task analyst assesses potential risk factors on the postures. This study may be able to be a fundamental study to develop an assessment method for lifting task analyses according to body postures.

• Korean journal of aerospace and environmental medicine
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• v.31 no.2
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• pp.38-44
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• 2021

Purpose: This study aimed to identify the prevalence of fatigue and its associated factors leading to the fatigue among Korean commercial airline pilots. Methods: An anonymous, web-based questionnaire collecting data on sleep related characteristics was completed by airline pilots. The final 1,029 samples of completed questionnaires were analyzed. The association of the risk factors with fatigue was determined using logistic regression analysis. Results: The prevalence of fatigue was 60% (Fatigue Severity Scale index≥3.2), disturbed sleep 28% (Pittsburgh Sleep Quality Index≥9), daytime sleepiness 17% (Epworth Sleepiness Scale≥10), and sleep apnea (Berlin Questionnaire≥2) 11%. The fully adjusted logistic regression showed that quality of life (odds ratio [OR]=0.16, confidence interval [CI]=0.11-0.24), daytime sleepiness (OR=1.26, CI=1.18-1.34), sleep quality (OR=1.44, CI=1.29-1.61), mental workload (OR=1.10, CI=1.05-1.14), vigorous physical activity (OR=0.82, CI=0.72-0.92), late starts (OR=1.25, CI=1.06-1.46) and average weekly flying hours (OR=1.02, CI=1.00-1.03) were associated with higher levels of fatigue. Conclusion: Lower quality of life, disturbed sleep, more subjective sleepiness, shorter sleep duration, higher mental workload, less vigorous physical activity, frequent late starts, and longer flying hour were shown to be risk factors for fatigue in airline pilots. These findings should be taken into account in the development of sleep and fatigue countermeasures for airline pilots.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.11
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• pp.1672-1681
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• 2002

To evaluate the thermal environments and the workload of farmers in the rice field in summer, this study investigated rice farmers' physiological, psychological responses, work postures, work clothes, air temperature and air humidity during the spraying pesticide in the rice field. Five career farmers (3 males, 2 females) volunteered as the subjects. During the spraying pesticide in the rice field, physiological responses were monitored continuously. The results were as follows. l. Farmers wore only raincoats not pesticide-proof clothing. 2. The value of WBGT, rectal temperature($T_{re}$), mean skin temperature(${\={T}}_{sk}$) were $24.9∼28.9^{\circ}C,\;37.8({\pm}0.3)^{\circ}C\;and\;33.6({\pm}0.6)^{\circ}C$, respectively. Clothing microclimate temperature($T_{cl}$) on the chest and back were $32.5({\pm}2.6)^{\circ}C\;and\;33.6({\pm}2.6)^{\circ}C$, respectively(p<0.00l). Humidity inside of the clothing ($H_{cl}$) was over 80%RH and heart rate(HR) was 112(${\pm}27$)bpm. We evaluated that the spraying pesticide was 'heavy work' by the Tre and HR. To four subjective questionnaires, all farmers expressed 'hard, hot, humid and uncomfortable' without individual difference at the end of works. We suggested that 1) the spraying pesticide in the rice field was a heavy work, 2) because the workload of farmers in the raincoat/pesticide-proof clothing can't be evaluated by only WBGT, assessors should measure physiological, psychological responses as well as thermal environments, 3) to alleviate farmers' heat strain, clothing manufacturers must consider not only the improvement of textile materials and clothing weight but also the designing of personal cooling equipment.

• Science of Emotion and Sensibility
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• v.23 no.2
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• pp.103-120
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• 2020

Using driving simulation, this study investigated the effects of driver's trust in the adaptive cruise control (ACC) system and road density on driver's workload and situation awareness. The drivers were allocated into one of four experimental conditions manipulated by ACC system trust level (trust-increased vs. trust-decreased) and road congestion (high vs. low). The workload and situational awareness of the participants were measured as dependent variables. The results showed followings. First, trust-decreased group for the ACC system had significantly lower trust scores for the system in all of the measurement items, including reducing the driving load and securing safe driving due to the use of this system, than the trust-increased group. Second, the trust-decreased group showed a slower reaction time in the secondary tasks and higher subjective workload than trust-increased group. Third, in contrast, the situational awareness for the driving situation was significantly higher in the trust-decreased group than trust-increased group. The results of this study showed that the driver's trust in the ACC system can affect the various information processing performed while driving. Also, these results suggest that trust in the user's system should be considered as an important variable in the design of an automated driving assistance system.

• Journal of the Ergonomics Society of Korea
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• v.28 no.1
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• pp.9-19
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• 2009

Repetitive movement, inadequate working posture, overuse of force, physical contact with sharp edge, vibration and temperature were well known risk factors of WMSDs (Work-related Musculoskeletal Disorders). Many researchers have investigated the relationship between inadequate working postures and incidences of WMSDs of the upper extremities, whereas relatively few researchers have tried to evaluate workload associated with the lower-body postures. The effects of lower-limb postures including various knee flexion angles on the subjective discomfort, heart rate and EMG of lower-limb muscles were investigated in this study. Thirty graduate students were asked to maintain thirteen different body postures, and heart rate and EMG data of five muscle groups (electro spine, biceps femoris, vastus medialis, gastrocnemius and tibialis anterior) from each posture were collected during fifteen minutes sustaining tasks. All participants were also asked to report their discomfort ratings of body parts. Results showed that high subjective discomfort ratings and heart rates were reported at the postures of knee angles of $60^{\circ}$ and $90^{\circ}$, whereas low discomfort ratings were founded at the postures of chair heights with 20cm, 40cm, and sitting with crossed legged. The change of median frequency for each muscle group during fifteen minutes tasks was investigated for each body posture to evaluate the relationship between muscle fatigue and body posture. It was found that the trends of changes of median frequency were different based on muscle group as well as lower-limb body posture from this study.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.47-58
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• 2013

Objective: The aim of this study is to review the job stress measurement for applying in nuclear power plants(NPPs). Background: The standard and guideline to evaluate and manage the job stress is insufficient in NPPs. Although job stress might have a negative effect on task performance particularly it can be related with human error in NPPs. Method/Results: This paper considered the objective and subjective stress measurements. One of the questionnaire(Korean Occupational Stress Scale) and the experiment method was investigated to apply in NPPs. KOSS was analyzed about the inter item consistency and correlation with the workload, and relative importance. In the objective evaluation considered the experiment method for the physical and mental job stress and analyzed from the phased point of view. Conclusion/Application: The measurement and criteria to evaluate job stress for operators must be complemented on the job characters and environments in NPPs. This study may support to confirm and manage the job stress in NPPs. The study of more specific methodology on job stress in NPPs is required on the basis of this paper.

• Journal of the Ergonomics Society of Korea
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• v.29 no.4
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• pp.625-629
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• 2010

This study has confirmed that subjective positive and negative aspects a driver feels by applying haptic seat on a vehicle to substantiate vehicle navigation system. Our experiment with total twenty subjects provides that the reaction time (RT) is superior in haptic interface than visual or auditory interface but subjective satisfaction, which subjects feel, and workload is less low in a simulator environment. Although, the difference of individuals and unfamiliarity is relatively high inasmuch as the experiment of absolutely new technology, but overall satisfaction of haptic seat is high. The result of study provides some consideration and direction to need in implementation of a haptic seat and it also confirms their possibility meaningfully. We expect the interaction between a driver and a vehicle and safety improvement potentially through applied haptic seat on actual vehicles.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.121-128
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• 2010

The purpose of this study is to confirm the impact of noise on subject accomplishment as well as physical/mental load, and evaluates the effects of noise-masking and earplug. 15 college students participate in the test, and the comparison is performed by executing four projects according to conditional categories of noise environments; control condition, noise condition, earplug condition, and noise-masking condition. Noise in the field site of the H manufacturer was used as the noise source, the general job aptitude test which consist of linguistic ability, math ability, perception ability, reasoning ability was used as the task of this project. To estimate physical/mental load evaluation, we used the heart rate R-R interval, Criteria flicker fusion frequency(CFF) and measured NASA-TLX workload for subjective evaluation. As the research outcome, it is shown that there is a meaningful difference for the project task score, dropping rate of CFF, the heart rate, and NASA-TLX subjective evaluation score according to conditions of noise environment. Therefore, the impact of noise on capability of subject accomplishment as well as physical/mental load was confirmed along with the effects of using earplug and noise-masking.

• Journal of the Ergonomics Society of Korea
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• v.30 no.6
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• pp.749-755
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• 2011

Objective: The purpose of this study is to assess the reducing effect of workload on developed electro-motion scissors. Methods: To achieve this, we measured the pressure distribution, Joint angle of fingers and JSI(Job Strain Index) for electro-motion scissors and hand-operated scissor in objective assessment and surveyed the uncomfortable degree in subjective assessment. Results: As a result, The peak of pressure in the electro-motion scissors was generally lower than the hand-operated scissors. JSI and overall joint angle of fingers for the electro-motion scissors were remarkably lower than the hand-operated scissors. Also, the subjective uncomfortable degree showed that the uncomfortable point of electro-motion scissors were generally lower than the hand operated scissors. Conclusion: The impact of reducing the work load as well as distributing the pressure around the hand by using electro-motion scissors during grapes pinching was confirmed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1722-1730
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• 2007

According to the result of recent studies, it was revealed that the error of safety-related personnel still plays a significant role in the accidents and/or incidents of a railway system. Accordingly, in order to reduce as well as prevent human errors, it is necessary to: (1) identify the root cause of accidents/incidents, and (2) conduct a research that can provide a systematic as well as an effective way to deal with the identified human errors. To this end, it is essential to suggest appropriate countermeasures based on the result of a task load analysis, which can soundly reduce a high level of the task load put on safety-related personnel. In the light of this concern, about the tasks of railway traffic signallers, a detailed task analysis was conducted in this study. After that, the associated task load scores were quantified by NASA-TLX technique that is one of the most well-known subjective workload measurement techniques. As a result, a set of significant tasks that could put a high task load on railway traffic signallers was identified.