• Journal of the Ergonomics Society of Korea
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• v.34 no.5
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• pp.377-399
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• 2015

Objective: The aim of this study is to understand and identify the critical issues in vision research area using content analysis and network analysis. Background: Vision, the most influential factor in information processing, has been studied in a wide range of area. As studies on vision are dispersed across a broad area of research and the number of published researches is ever increasing, a bibliometric analysis towards literature would assist researchers in understanding and identifying critical issues in their research. Method: In this study, content and network analysis were applied on the meta-data of literatures collected using three search keywords: 'visual search', 'eye movement', and 'eye tracking'. Results: Content analysis focuses on extracting meaningful information from the text, deducting seven categories of research area; 'stimuli and task', 'condition', 'measures', 'participants', 'eye movement behavior', 'biological system', and 'cognitive process'. Network analysis extracts relational aspect of research areas, presenting characteristics of sub-groups identified by community detection algorithm. Conclusion: Using these methods, studies on vision were quantitatively analyzed and the results helped understand the overall relation between concepts and keywords. Application: The results of this study suggests that the use of content and network analysis helps identifying not only trends of specific research areas but also the relational aspects of each research issue while minimizing researchers' bias. Moreover, the investigated structural relationship would help identify the interrelated subjects from a macroscopic view.

• Journal of the Ergonomics Society of Korea
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• v.34 no.5
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• pp.501-517
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• 2015

Objective: The aim of this study was to investigate the technology trend on developing helmets based on the analysis of Korean, US, European and PCT patents. Background: The usage of the personal protective equipment such as the safety helmet would be essential for preventing injuries and reducing the severity of injuries depending on the type of activity and the exposed environment. Method: Database of WIPSON was used for searching the patents. The objects were the Korean, US, European and PCT patents registered or opened from January 2011 to December 2014. The keyword to investigate was helmet, and International Patent Classification (IPC) was used for investigating the technology trend of the patents. Results: The cases of US patents annually increased, but the cases of European patents decreased. US patents belonged to all sections but Korean and European patents and PCT patents did not. The largest number of IPC, to which four areas' patents belonged, was 'Headwear' and the second largest one was 'Hygiene'. In the subgroup level, the most common largest subgroups were 'Parts, details or accessories of helmets' and 'Masks, shields, or hoods for welders'. Korean patents had the lowest ratio of single_IPC at 11%, but the ratios of single_IPC for US and European patents were 52%, respectively. 'Human necessities', 'Mechanical engineering', 'Physics', and 'Electricity' were used as a single_IPC, but lower levels of 'Performing operations', 'Chemistry', 'Textiles' and 'Fixed constructions' were used as multi_IPC. Most main applicants had patents which belonged to 'Human necessities'. Conclusion: The cases of US patents annually increased unlike others. The common technologies for creating the helmet were Parts of helmets under Headwear and Shields for welders under Hygiene. Many Korean patents tended to be categorized as multi_IPC, different from others. Application: To know the technological characteristic of patents would be helpful to initial stage developers.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.347-356
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• 2010

The purpose of this study is to analyze the spine stability by comparing muscle activation in various scaffold working conditions. The independent working conditions were designed by two levels of working height, existence and absence of safety handrail, and the two levels of expertise. The corresponding activities of the agonist and antagonist muscles of spine were simultaneously recorded by using EMG. As results, novice worker showed increased muscle activity while doing the task on the 2nd floor, absence of handrail. And expert showed the increase of co-contraction while working on the 2nd floor without handrail. Such co-contraction was found to increase the spine stability when the working condition become risky. On the other hand, the co-contraction was prolonged, the spine muscle fatique and disc pressure could be increased, which would increase the risk of musculo-skeletal disorder. The results of co-contraction in this study indicates that the motor control system responds to maintain the stability of the spine particularly when workers cognitively recognize the danger of falling or imbalance. This study also quantitatively accounted for the biomechanical cause of LBP among workers who has to prevent themselves from falling. Therefore, if can be said that safe environment preventing falling can also prevent workers from MSDs as well. Such knowledge can be applied to design ergonomic workplace environment as well as movable scaffold.

• Journal of the Ergonomics Society of Korea
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• v.31 no.3
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• pp.437-444
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• 2012

The purpose of this study was to suggest appropriate human model for ergonomic evaluation considering working postures on 3D space. Background: Traditionally extreme design rules have been widely utilized at the stage of designing products. Body size of 5th percentile and 95th percentile in stature has been generally selected for controllability and clearance evaluation, respectively. However, these rules had limitations in reflecting working posture in ergonomic evaluation. Method: In order to define working posture on 3D space, not only sagittal plane but also lateral plane was considered. Kinematic linkage body model was utilized for representation of working posture. By utilizing the anthropometric data of 2,836 South Korean male populations, the point cloud for end points of linkage models was derived. The individuals who were lacking in certain controllability were selected as human models for the evaluation. Result: In case of standing posture it was found that conventional approach is proper for all controllability evaluations. Contrary to standing posture, tall people had less controllability on control location below shoulder point in sitting posture. Conclusion: From the derived proper range on controllability, ergonomic evaluation rule was suggested according to working posture especially in standing and sitting. Application: The results of the study are expected to aid in selection of appropriate human model for ergonomic evaluation and to improve the usability of products and work space.

• Journal of the Ergonomics Society of Korea
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• v.29 no.4
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• pp.585-593
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• 2010

Recently, we designed an interactive virtual space for the multi-purpose hall in Songdo Future City, located in Incheon, Korea. The goal of the design is to make a virtual space that is flexible and can be adjusted thanks to its unfixed seats in order to accommodate different and unspecified audience sizes. Virtual images are interactively adjusted according to the distance, position and size of audiences, information about which is detected by 9 photo sensors. To increase the sense of immersion, intensity and reality, we utilized the technology of scent display that can create appropriate scents to match the images on the screen. The intensity and persistence of scents were determined by the size, distance and position of audiences. The virtual image contains background images and reactive images. The background images repeatedly project images of spring, summer, autumn and winter. The reactive images consist of small portraits or pictures or icons that define or characterize the season types, and these are added to the background image according to the distance, position and size of the audiences.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.67-71
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• 2010

This study examined the field of view of older drivers based on their eye points. The subjects were 25 people whose age was over 65 years and 10 contrasting subjects on their 20s. For the experiment, we expanded the width of the A-pillar of a test vehicle. With a measuring apparatus designed for the study, we analyzed 3 axes of coordinates from glabella to a fixed point of the vehicle that would be used as CAD data of vehicle design. Result shows that average eye point of the older subjects was located significantly farther from the seat than that of the 20s approximately by 31.62mm(p=0.05). It was also found that the Binocular FOV was not significantly different between the older subjects and the 20s(p=0.85), and the effect of the width of the A-pillar on the FOV could not be found. We also measured the left and right side of the Ambinocular FOV of the older subjects. It was found that the older subjects had much wider visual angle than the 20s by 2.84 degree (F=4.78, p=0.01) on the left side, while the 20s showed significantly wider average angle than the older subjects by about 4.88 degree (F=4.78, p<0.05) on the right side. The results of this study can be used to improve the FOV based on the optimal eye points when designing a vehicle for older drivers.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.47-53
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• 2010

An analysis of biosignal and performance data collected during driving has increasingly employed in research to explore a human-vehicle interface design for better safety and comfort. The present study developed a protocol and a system to effectively analyze biosignal and driving performance measurements in various driving conditions. Electrocardiogram (ECG), respiration rate (RR), and skin conductance level (SCL) were selected for biosignal analysis in the study. A data processing and analysis protocol was established based on a comprehensive review of related literature. Then, the established analysis protocol was implemented to a computerized system so that immense data of biosignal and driving performance can be analyzed with ease, efficiency, and effectiveness for an individual and/or a group of individuals of interest. The developed analysis system would be of use to examine the effects of driving conditions to cognitive workload and driving performance.

• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.65-73
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• 2007

This study evaluated the short message service (SMS) and multimedia message service (MMS) usability of mobile phones and wireless internet services by performance failure rates and flowcharts that adopted the concept of state diagrams. Forty-eight participants who had an experience of using mobile phones were recruited by posting an advertisement on websites for the experiment. They carried out both SMS and MMS tasks with the mobile phones of LG Cyon and Samsung Anycall as well as the wireless internet services of LGT ez-i, KTF magicN, and SKT NATE. In general, Cyon had the lower performance failure rate than Anycall for SMS, and ez-i had the lowest performance failure rate than the other services for MMS. More specifically through the workflow analysis, most participants used hot keys to take 7-8 steps to send a SMS including a symbol and had a difficulty in typing the symbol. They also took 10-11 steps to send a MMS after taking and attaching two pictures. Anycall, magicN, and NATE had significantly large error and failure rates due to the limited option of the menu paths that users could take and poor compatibilities of menu names and between menu and navigation keys. This study showed the possibility of use of flowcharts for systematic and specific usability evaluation methods and found the causes of performance errors and failures with mobile phones and wireless internet services to provide insight into their design.

• Journal of the Ergonomics Society of Korea
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• v.36 no.3
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• pp.213-219
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• 2017

Objective: The present study identified the minimum legible text size by an experiment for eight combinations of background and text colors, which will be used in designing visual information on group-view display (GVD). Background: Information on minimum legible text size is needed to design the visual information presented on GVD in a radioactive waste control room. Method: The experiment was conducted for 22 male participants (age: mean = 37, SD = 6.7; visual acuity: over 0.8) who were recruited by considering demographic characteristics of current control room operators. Eight combinations of background and text colors were considered and the minimum legible text size was determined for each combination by applying the method of limits, one of psychophysical methods. Results: The minimum legible text size was significantly different in accordance with the combination of background and text colors. Statistical analysis results showed that luminance contrast and color contrast between background and text influenced the minimum legible text sizes. Conclusion: This study concluded that the minimum legible text size is 8 minute of arc for various combinations of background and text colors. Application: The minimum legible text size identified in the present study can be utilized in designing visual information on GVD at the main control room in a radioactive waste facility.

• Journal of the Ergonomics Society of Korea
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• v.35 no.3
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• pp.175-184
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• 2016

Objective: In this study, two types of foot-controlled mouse devices are compared with a hand mouse in the input tasks requiring repetitively switching between a keyboard and a mouse. Background: Foot-controlled mouse devices have been developed for persons with impairments in the mobility of their hands. However, some researchers insisted that the foot-controlled mouse devices could be effectively used by the persons with no limits to their hand mobility. There are needs to investigate the efficiency of the foot-controlled mouse devices, when they are used by the nondisabled people. Method: Participants conducted the input tasks, requiring repetitive switches between a keyboard and a computer mouse. The used computer mouse devices were two types of foot-controlled mouse and a typical hand mouse. Participants performed three types of input task for five days and three types of task performance were measured; the number of completed input tasks within a given practice time, subjective satisfaction level and the time wasted for the mouse control. Results: For five days, the performance of input tasks sharply increased in input tasks by foot-controlled mouse devices rather than a hand mouse. After five days, the level of satisfaction on the foot-controlled mouse devices approached to about 76% of a hand mouse satisfaction level. The control time of the foot-controlled mouse devices also approached to about 109% of a hand mouse control time. Conclusion: After only five-day practice, the input task performance by foot-controlled mouse devices approached to that of a hand mouse. This result may suggest that the foot-controlled mouse devices can be effectively used as an alternative input device for the nondisabled people, if input tasks are easy and enough practice time is provided. Application: The results of this study might help to design foot-controlled mouse devices and to expend the usage of them.