• Journal of the Korea Furniture Society
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• v.15 no.1
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• pp.41-52
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• 2004

Most of us spend the greater part of our lives at the chair, but of all the man environments it is maybe the least well-explored share commitment to a cleaner and healthier environment. It has long been chairs belief that the environment is a precious gift. In case of mesh chair, because it depend upon the earth's resources to design and manufacture steel furniture products, human beings feel an abiding responsibility to act wisely in the environmental choices we make, large and small, every day. Ergonomically, it ought to do more than just sit there. It should actively intercede for the health of the person who sits in it longer than it should. Therefore, product design should be approachable to satisfaction of end-users in aspect of value engineering easy to move through analysis of cost reduction factors the purpose of this thesis is to study products for users based on office chair to development of design for office chair by analysis of manufacturing status and methods and problems in Korea through research on actual situation as well as changing process ergonomic study and design of office chair.

• Journal of the Ergonomics Society of Korea
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• v.13 no.2
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• pp.13-24
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• 1994

The objectives of this study are twofold : (1) to investigate musculoskeletal discomfort for sedentary workers in offices ane (2) to revise the Korean Standard for the design of office chairs in order to reduce or eliminate the physical discomfort or the office workers. Two hundred seventy-one office workers from nineteen different companies companies were selected to evaluate the musculoskeletal discomfort and indibidual features of chair design. A statistical analysis of the survey rebealed that the office currently being used had two major deficiencies such as insufficient adjustability and inappropriate design specifications in ergonomic sense. A stepwise regression analysis showed that the deficiencies on the musculoskeletal discomfort of the workers. Based on the ergonomic design pronciples, was debeloped to revise the Korean Standard for the design specifications of office chairs. An application of the methodology was made amend the design specifications of the four factors such as seat pan height, seat pan width, and seat pan inclunation. Their effects were evident in the musculoskeletal discomfort of the workers.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.125-134
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• 2014

Objective: The purpose of this study is to evaluate integral seat desk used in universities through comparison of real dimension values of the desk with KS/ISO standard and questionnaire survey. Background: School furniture that helps students sit comfortably for longer periods of time and allows for better concentration on learning is important. However, seat and desk have been generally designed based on the industry practice rather than user's anthropometry, and seats and desks used in universities of Korea have not been ergonomically evaluated. Method: Real 13 dimensions of the desk used in K University were measured using tape measure and inclinometer, and the dimension values were compared to the KS standard of desk and chair for lecture room (KS G 4210) and ergonomic design principles found in relevant references. Subjective appropriacies and preference for the desk were investigated based on questionnaire survey, in which 121 (male: 91, female: 30) college students participated. Results: Several dimensions for the desk and chair investigated except desk depth and width, leg room width, seat width have not met the KS standard, but all dimensions satisfied ergonomic design principles available in references. The questionnaire survey revealed that appropriacies for desk surface size, seat pan depth, seat pan cushion and backrest curvature were under middle point of 3.0, and that those for the other dimensions showed higher scores exceeding 3.0. Conclusion: The integral seat desk widely used in universities showed some design problems in terms of standards of KS G 2010 and KS G 4210, and ergonomic design principles. Compared to the general desk with separated desk and seat, subjective preference on the integral seat desk was low. Application: This would be used as a valuable guideline when designing or choosing new integral seat desk with high satisfaction of students.

• Journal of the Ergonomics Society of Korea
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• v.34 no.2
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• pp.151-165
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• 2015

Objective: This study aims to develop and scientifically investigate the efficacy of the Spine S-curve Reactive Backrest that responds to the spine curvature of the user when seated, and maintains and enhances the natural S-curve of the lower back, thereby helping to relieve fatigue, correct posture and prevent spine deformities. Background: The focus of current development, design guidelines and/or standards for office chairs is mainly placed on the chair's dimensions, incline angle, adjusting features and lumbar support. Research and development was called for developing a chair backrest that maintains and improves the S-curve of the full spine. Method: The Spine S-curve Reactive Backrest was ergonomically designed to maintain correct posture and enhance user comfort. When leaned on, the backrest responds to the user's spine line and the whole lower back sits closely against the backrest, thereby aligning the user's lower back and backrest as one to maintain and improve the natural S-curve formation of the spine. In order to evaluate the efficacy of the newly designed chair (new design) and the comparison target (chair), five male college students of standard body type with normal spine curvature were selected as test subjects, and a motion analyzer and electromyography were utilized to measure S-curve and erector spinae muscle activity when seated. Results: The spine S-curve was better maintained and improved when sitting in the new design than in the comparison chair. Particularly notable was the greater displacement gap of the thoracic spine than the cervical spine, and also that of the lumbar more than the thoracic spine, with the increase of the backrest tilting angle. Furthermore, the electromyogram results showed the new design caused a lower fatigue level of the erector spinae muscles compared to the comparison chair, and also earned a higher preference in the subjective opinion results. Conclusion: The newly designed chair in this study responds to the user's spine curvature and maintains and enhances the lower back's natural S-curve, and thereby relieves fatigue, promotes better posture, and helps to prevent spine deformities better than existing office chairs. There is a need to widely introduce and supply this new design. Application: The new design is applicable to office and student chairs, and is expected to improve concentration and work efficiency.

• Journal of the Korea Furniture Society
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• v.22 no.3
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• pp.151-159
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• 2011

This study is to suggest versatile chair designs that are organically shaped to take individual orientation. This study intends to provide design method to ensure the face of the chair that contacts the body of its user is transformed flexibly to support the body. The movement of human body is not just a behavior but the ways and tools that reflexively express against external stimuli that are sensed and identified by the person. The versatile chair whose users' sitting position is fixed is made by covering the lump form with a piece of cloth ensuring that the content is firmly fixed and by placing the beads-woven wood fabric according to the shape. And then, it is covered with the external cover. The proposed versatile chair designs assume specific forms as follows: First, it is a versatile chair whose user's sitting position can fix. The organically-shaped form that can accept varying postures is made as a mass, which changes into different shapes when human body touches the form so that users can lie down or sit. Due to such transformation, body posture is determined and individual differences in shape changing are all acceptable. Second, it is a versatile chair that reflects the user's position in a fixed chair, where a cloth-wrapper feature is applied to the form a sifit wrapped postures so that a variety of body postures can be accepted. Finally, a versatile chair that reflects the user's position by changing the shape of is covered with forms so that it will be transformed and used in accordance with situations and chair shapes and reflect multiple shapes including round or square ones.

• Journal of the Ergonomics Society of Korea
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• v.30 no.3
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• pp.395-401
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• 2011

Objective: This study examined the effects of working chair that was developed for farmers who work in grapevine's cluster thinning. Background: Agricultural work involves some of the nation's highest occupational risk exposures. Fruit cultivation has been recognized as one of the most hazardous crops in which to work. Grapevine cluster thinning task involve activities related to the main risk factors associated with upper limb work-related musculoskeletal disorders. Method: An experiment was designed to test the working chair. Six healthy male($25.8{\pm}4.9years$) were selected as the subjects for this study. Electromyography(EMG) was used to monitor the muscles activity, and Electro-goniometer was used to measure the ranges of motions of the elbow, trunk and knee. Subjective test was also carried out to examine discomfort body parts and their pain intensity. A grapevine's working space was built for the experiment and working chair was installed on it. In order to examine the muscle activity and range of motion, subjects used to the working chair for 30 minutes for each experimental condition. Another test without working chair was also performed for comparison. %MVC was used to quantify the level of muscle activity. Results: Decreases of muscle activity was found in all leg muscles and significant decrease of muscle activity was found in left Gastrocnemius. The range of motion of the trunk and knee also decreased when working chair used. Discomfort in lower back, thigh and shank region were reduced significantly. However, in upper limbs muscle activity tended to increase in working chair compared with conventional task. Conclusion: Improvement for cushion in seat back and pan required to reduce discomfort in buttocks. Application: Overall findings verified that the working chair might help to prevent upper limb and lower back MSDs based on the current study. These results can be practically used for work improvement for the grapevine growers to prevent MSDs.

• Journal of the Korean Society for Library and Information Science
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• v.35 no.1
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• pp.101-122
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• 2001

To take maximum advantage of computers without compromising the health of library staffs and users, it is important that the computer workstation be adapted to the needs of the users. While the topic of occupational safety and health is a major industry concern, it is not commonplace in libraries. Therefore, this study is to apply the ergonomic principles to library computer workstations and suggest the ergonomic models for computer table and chair, monitor and keyboard placement, posture and motion. lighting, and other environments.

• Journal of the Ergonomics Society of Korea
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• v.20 no.1
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• pp.15-29
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• 2001

This study was conducted to develop a prototype of adjustable desk and chair for students from elementary to high school. The development process started with identifying the problems of existing adjustable desks and chairs that are currently available in the market. The following fundamental design criteria were established and then applied to develop the prototype. The criterion of minimization of production cost yielding lower the market selling price was the most critically considered in view of the school furniture buyers' price-consciousness. Other design criteria used in this development were designing for stable and solid structure, requiring few motions and no tools to adjust, requiring the use of only one hand to adjust, unrestricting the adjustable interval, providing extra space for foot and knee area, reducing weight to move easily, and requiring not to move around for cleaning up floor. To evaluate the performance of the prototype, the adjustability of prototype was specifically compared with both dimensions suggested by KS G 2010(Korean Standards for desks and chairs for students) and current anthropometric dimension in terms of the flexible range of accommodation. Results of this study illustrate that the prototype developed in this study could be accommodated for the both dimensions. As a concluding mark, appropriate adjustable range for various grades and age groups were presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.611-612
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• 2009

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.1-9
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• 2023

Objective: This study identifies the difference among the heights of a chair's backrest (High, Mid, No), the biomechanical changes chair users undergo over time, and the variables that can measure musculoskeletal disorders, eventually providing information on the appropriate type of backrest. Method: Eleven healthy subjects in their 20s and 30s who had no experience with musculoskeletal disorders or surgical operations within the last 6 months participated in this study. Computer typing tasks were randomly designated and performed according to the type of chair backrest, and evaluation was performed for Flexion-Relaxation Ratio (FRR) analysis after the computer typing tasks. This study used eight infrared cameras (sampling rate: 100 Hz) and nine-channel electromyography (sampling rate: 1,000 Hz). ANOVA with repeated measures was conducted to verify the results, with the statistical significance level being α = .05. Results: Although there was no significant difference in craniovertebral angle (CVA), this study showed time and interaction effects depending on the height of the backrest (p<.05). When working without the backrest, the head-spine angle was lower compared to the chairs with backrest, based on the computer work. As for the head angle, the higher the back of the chair was, the less the head flexion and the body angle became, whereas the body flexion became less when there was a backrest. In addition, the body flexion increased over time in all types of backrests (p<.05). The muscle activity of the upper body tended to be high in the high backrest chair. On the other hand, a lower muscle activity was found with a low backrest. Conclusion: These results show that a chair is more ergonomic when the body angle is correctly set without bending and when it is supported by a low backrest. Accordingly, this study determines that the backrest affects shoulder and neck musculoskeletal disorders during typing and that medium-height backrest chairs can help prevent musculoskeletal disorders, contrary to the expectation that high-backrest chairs are preferable.