• Design & Manufacturing
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• v.13 no.1
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• pp.48-54
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• 2019

Analytical and experimental study were carried out in order to achieve simultaneous coating and injection molding of an automotive armrest. A mold was designed to be included one core and two cavities, which were composed of a substrate cavity and a coating cavity. The materials used were PC/ABS for substrate and 2-component Polyurethane for coating. The predicted flow patterns were in good agreement with experimental results in injection molding and in-mold coating. Based on analysis and experiment, it was found that the optimal processing conditions were packing pressure of 90MPa and holding time of 7sec.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.63-68
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• 2013

Manual wheelchair is one of the most used assistant device in Korea and the size of the wheelchair is defined as KS P ISO 7176-5 which follows the ISO 7176-5 standard size. But the standard often doesn't fit to Korean people because the ISO was enacted by foreigners' body sizes. Actually the result of survey from the Korean Agency for Technology and Standards showd that the designated sizes of height, width, deep of seat except armrest and the height of backrest of a chair in the present KS P ISO 7176-5 are much bigger and the height of armrest is smaller than the sizes investigated by the survey. In case the disabled person has a long wheelchair use time everyday, the posture of user should be uncomfortable because the mismatched size should cause user's pelvis rotations, slouching pose and low stability. Also, inside of knee may touch the wheelchair seat and user can't keep a correct posture. In this paper, the body sizes of Korean disabled person were investigated and the correct wheelchair sizes for Korean people are provided.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.1
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• pp.16-24
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• 2009

This research aims to measure and analyze the dimensions of typical office chairs and desks sold in domestic market, and to suggest the modifications of national guidelines considering Korean peoples' body characteristics. The scope of this study was limited to the desktop type of computer jobs, excluding laptop environment. The dimensions of 24 different office chairs and 7 tables were measured, and their dimensions were analyzed against the Ministry of Labor (MOL) Notification and Korean Standards (KS). At the same time, the data from the Size Korea was also considered. As a result, the KS guidelines were overall fulfilled by the measured products, while the MOL Notification was not. It was found that the guidelines on the chair height, seat pan depth, lumber support height, and armrest height need to be modified. Some inconsistencies between the MOL Notification and KS were also found. It is suggested that the required dimensions specified by both guidelines should be unified.

• Korean Journal of Computational Design and Engineering
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• v.9 no.4
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• pp.277-285
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• 2004

In this paper, a 2 DOF haptic yawing joystick for use as the navigation input device in virtual environments is introduced. The haptic yawing joystick has 360° range for yawing motion and ±100° for pitching motion. The device can support weights of up to 26N for χ axis and 10N for axis with 10kHz of sampling rate. The size of the haptic yawing joystick is so small that it can be assembled on armrest of an arm chair and has relatively larger work space than other conventional 2 DOF joysticks. For the haptic yawing joystick, an ellipse navigation algorithm using the user's velocity in the virtual navigation is proposed. The ellipse represents the velocity of the user. According to the velocity of the navigator, the ellipse size is supposed to be changed. Since the path width of navigation environments is limited, the ellipse size is also limited. The ellipse navigation algorithm is tested in 2 dimensional virtual environments. The test results show that the average velocity of the navigation with the algorithm is faster than the average navigation velocity without the algorithm.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.1
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• pp.74-78
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• 2015

A bus seat is required to be ergonomically designed in terms of its shape and physical properties to increase seating comfort. The present study is intended to develop a systematic bus seat evaluation protocol based on seating comfort. A total of 48 participants evaluated 12 parts (seat belt, recliner, armrest, headrest, upper-back support, lumbar support, seatback bolster, seatback overall, hip support, thigh support, seatpan bolster, and seatpan overall) of 12 bus seats with 17 subjective comfort measures (e.g., convenience of control, suitability of size, and overall comfort). Lastly, ergonomic features of shape and physical properties of each seat part were identified based on the subject evaluation analysis results. The developed bus seat evaluation protocol can be applied to evaluate various types of seats.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.81-84
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• 2015

Purpose: The purpose of this study was to compare the effect of 'knowledge of result' and 'knowledge of performance', two types of extrinsic feedbacks, during the sit-to-stand movement in children with hemiplegic cerebral palsy. Methods: A total of ten children with hemiplegic cerebral palsy (ages 8 to 12 years) were recruited for the study. Subjects with hemiplegic cerebral palsy performed sit-to-stand movement in front of a mirror. Their performance was supervised and revised for normal movement by a pediatric physiotherapist. In the knowledge of the result, subjects performed sit-to-stand using a chair with an armrest in their mind with normal movement. In the knowledge of performance, subjects performed sit-to-stand under verbal instructions. Randomized cross over trials were used in this study. Main outcome measurements were as follows: mediolateral speed, anteroposterior speed, velocity moment, extent in mediolateral direction, extent in anteroposterior direction, and vertical distance of the center of pressure. Results: The mediolateral speed and extent of center of pressure was higher for 'knowledge of performance' in comparison with the other type of extrinsic feedbacks (p<0.05). The other parameters, including anteroposterior speed and extent, and vertical speed of the center of pressure, did not differ between the two types of extrinsic feedbacks (p>0.05). Conclusion: These findings suggested that training in sit-to-stand movement with 'knowledge of result' may result in better use of extrinsic feedback.

• Journal of the Ergonomics Society of Korea
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• v.26 no.3
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• pp.111-115
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• 2007

Design equations for anthropometric product design are developed by considering the geometrical relationships of design dimensions and anthropometric dimensions. The present study applied the design structure matrix (DSM) method to the development of design equations for a computer workstation, and compared design values from the design equations with corresponding design values of ergonomic recommendations and existing products. The relationships between design dimensions (e.g., legroom and worktable) were analyzed by a DSM, and then the application order of design equations (e.g., seatpan, backrest, armrest, legroom, and worktable in descending order) was determined. Next, design equations were developed by analyzing the geometric relationships between computer workstation design dimensions and anthropometric dimensions. Finally, design values for a computer workstation were determined by considering a standard posture defined and representative human models (5th, 50th, 95th %ile). The design values calculated using the design equations were similar with those of ergonomic recommendations found in literature and two commercial products measured in the study; however, some design values (e.g., seatpan height) were different due to discrepancy in standard posture. The DSM method would be utilized to systematically analyze the relationships between design dimensions for anthropometric product design.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.1
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• pp.59-64
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• 2015

This study focuses on the dimensions of tractor seat, which is one of the important link between the tractor and the operator based on ergonomic approach in the design process. 7 anthropometric data sets were introduced from Korean and US anthropometric database for adult male and female including length of buttock to back of knee (sitting), height of lowest point of shoulder blade (sitting), underside elbow height (sitting), and so on. Design factor for the tractor seat included dimensions of seating surface, dimensions of backrest surface, and the location of armrest. The shape of spinal curve and clothing correction should be also considered during the design process. The result of this study can be used as a guideline for the design process of tractor seat.

• Journal of Preventive Medicine and Public Health
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• v.57 no.5
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• pp.451-460
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• 2024

Objectives: This study aimed to identify workstation factors influencing work-related musculoskeletal disorders (WMSDs) among information technology (IT) professionals in Indonesia. Methods: A cross-sectional study was conducted among 150 IT workers at small-enterprise companies who were randomly selected across East Java, Indonesia. The data were modeled using multiple linear regression, with a 95% level of confidence for determining statistical significance. Results: The respondents reported that the neck had the highest level of discomfort and was the most at risk of WMSDs, followed by the lower back, right shoulder, and upper back. Screen use duration (p=0.040) was associated with whole-body WMSDs, along with seat width (p=0.059), armrest (p=0.027), monitor (p=0.046), and a combined telephone and monitor score (p=0.028). Meanwhile, the factors significantly related to the risk of WMSDs in the hands and wrist were working period (p=0.039), night shift (p=0.024), backrest (p=0.008), and mouse score (p=0.032). Conclusions: Occupational safety authorities, standards-setting departments, and policymakers should prioritize addressing the risk factors for WMSDs among IT professionals.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.687-692
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• 2015

A mold design for in-mold coating was developed to achieve simultaneous coating and injection molding of an automotive armrest. The developed mold includes one core and two cavities which are composed of a substrate cavity and a coating cavity. The core was attached to a movable plate and two cavities were mounted on a plate sliding in a stationary plate. In a two-step process, the part was first injection molded and subsequently, with the aid of a sliding table, was transferred to a second cavity. The materials used were PC/ABS for substrate and two-component polyurethane for coating. The experiments were conducted by changing the flow rate to investigate mixing characteristics. As the flow rate increased, the mixing improved. Additionally, the bubbles appeared over the substrate surface decreased with an increase of the weight of injected coating material.