• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.97-108
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• 2014

Objective:The present study is intended to evaluate the usability of a console chair for a weapon locating radar by comparing with different kinds of chair design. Background: Console chairs need to be ergonomically designed to reduce physical workload of operators and improve mission capability; few studies have been reported which systematically evaluate usability of military console chairs. Method: Ergonomic design of a console chair, a bus seat, and an office chair was evaluated in terms of headrest, seatback, seatpan, armrest, and controller on a 7-point scale. Ten males in their 20s and 30s were recruited considering the demographic characteristics of console operators. Results: The satisfaction scores of the console chair for headrest, seatback, and seatpan were significantly higher than those of the bus seat (mean difference [MD] = 0.9) and office chair (MD = 1.3). Meanwhile, the satisfaction scores of the console chair for armrest and controller were significantly lower than those of the office chair (MD = -1.4) and bus seat (MD = -2.2). Conclusion: The armrest and controller of the console chair needs ergonomic improvements for better comfort. Application: The evaluation results of the console chair would be of use for ergonomic console chair design.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.145-152
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• 2013

Objective: The aim of this study is to develop an ergonomic office chair that has an alarm function for the unbalanced sitting postures. Background: Contrary to expectation, it is reported that office workers sit on their chairs much more in unbalanced postures during daily work. Even though an office worker uses an ergonomically good-designed chair and begins their work in a good sitting posture, his/her posture is likely to shift to the unbalanced bad posture. Therefore, a posture alarm system would be very helpful in keeping office workers' good postures. Method: We developed a prototype chair with four load cells under a seat pan and one load cell beneath a backrest. Through some experiments, we set the criteria for unbalanced bad postures then implemented the criteria into the alarm system of the prototype chair. The chair called e-BASE chair could detect unbalance postures and show alarms for chair users. We also enhanced back support by developing a step-wised folding backrest. Results: The e-BASE chair showed better performance in interface pressure distributions and balanced posture ratio in VDT work. Conclusion: The ergonomic chair with posture alarm function(e-BASE chair) was developed. It showed better performance in seat pressure distribution and in keeping good posture during office work. Application: The posture alarm system and folding backrest can be applied to the new models of office chair.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.143-153
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• 2014

Objective: The aim of this study is to investigate the effects of trunk-forearm supported sitting on trunk flexion angle, trunk extensor fatigue and seat contact pressure. Background: The relationship between sitting posture and musculoskeletal disorders of the trunk extensor fatigue and seat contact pressure has been documented. The trunk-forearm support type ergonomic chair was devised from the fact that trunk-forearm support has been reported to reduce trunk extensor activity and discomfort. Method: Using three different sitting postures, upright ($P_1$), trunk-forearm supported ($P_2$) and normal sitting ($P_3$), six healthy subjects participated in the study. Motion capture system was used to collect head and trunk flexion angle, and surface electromyography (sEMG) was used to collect myoelectric signal of upper trapezius, lower trapezius, erector spinae, multifidus, and pressure mat system was used to measure seat contact pressure. Results: When trunk and forearm were supported by the ergonomic chair, higher head flexion angle showed upright > trunk-forearm supported > normal in order, and muscle fatigue showed less than upright and normal sitting. Mean seat contact pressure decreased 19% than upright sitting. But muscle fatigue was not affected by each condition. Conclusion: Trunk-forearm supported sitting of the ergonomic chair showed positive effect in respect of trunk and head flexion angle, trunk extensor fatigue, seat contact pressure. To acquire comprehensive understanding of the effectiveness of the ergonomic chair, further studies such as anatomical effects from measurement of external applied loading effect to the body from interface pressure analysis are required. Application: The results of the publishing trend analysis might help physiological effects of trunk-forearm support type chair.

• The Journal of Korea Robotics Society
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• v.4 no.3
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• pp.243-249
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• 2009

In modern society, people spend most of their time on various types of chairs. However, it is not easy for a designer to design a comfortable chair because satisfaction with the chair depends not only on the quantitative elements such as size, but also on the qualitative element such as the user's feeling. To deal with these problems, there have been many studies on designing ergonomic chairs. This paper proposes the haptic-aided design (HAD) system to design an ergonomic chair. Based on the HAD system, the designer can experience whether the chair is comfortable or not through the haptic device, and also can modify the design parameters instantaneously. The haptic chair capable of controlling the design parameters in real time was proposed as a haptic simulator. The controllable parameters, such as seat height, reclining angle, stiffness of the backrest, and so on were selected based on the previous research related to ergonomic chairs. The proposed methodology will help reduce the development cost and time by replacing the process of making the real mock-ups and prototypes with the haptic chair.

• Journal of the Korea Furniture Society
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• v.10 no.1
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• pp.13-21
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• 1999

All chairs are uncomfortable in the long run and some chairs become uncomfortable more rapidly than others. In a particular chair, some people feel more uncomfortable than others. Comfort will depend upon the interaction of chair, user, and task characteristics. In this study, we intended to design a comfortable office chair by investigating anthropometric and biomechanical aspects for Koreans. We determine the design dimensions by analysis the anthropometric data. With these body parameters, we determined the design dimensions such as seat height, seat depth, seat width, seat backrest width, etc. This research, hopefully contributes to the development of ergonomic chair and improvement of the chair design technologies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.949-950
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• 2011

• Journal of the Ergonomics Society of Korea
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• v.19 no.1
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• pp.23-36
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• 2000

In conventional ergonomics, consumer product can be made based on anthropometric data and specific design guideline. However, the product may not satisfy consumers because their emotional preference have not been properly considered in design phase. Therefore, in this study a new chair design process was introduced by which both consumer's emotional need and traditional ergonomic requirement can be satisfied. As a part of the process, the traditional Kansei engineering technique was modified to collect quantitative information of consumer's visual appreciation and physical feedback of various types of chairs. Furthermore, we developed an interface, so called, KADAS(Kamsung Analysis and Design Assistance System), for designers to use the technique in chair design. This software can help designers to understand what should be the most suitable shape in designing items such as seat, back and arm rest, etc. to meet the emotional need of consumers. This software displays the result of modified quantification theory I, and explains how to use the statistics. This study suggested a new approach for ergonomic design incorporated with Kansei Engineering technique. This technique can be also applied to other products by extending the database of KADAS.

• Journal of the Korea Furniture Society
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• v.13 no.2
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• pp.53-62
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• 2002

Due to the industrial development some scholars insist that homo sapiens has become a new race--homo sedens. Since this great degree of behavioral change often cause problems in the spinal column, the appropriate sitting became critical. The nineteenth-century idea of sitting upright position is not considered as a proper sitting any longer. Recent studies by such psychological scientists as A. C. Mandal, Ernest McCormick, and Karl Kroemer show that the spinal column in s-curve with forward bends should be efficiently supported in that manner. Designing a chair sometimes focuses on aesthetic points rather than true ergonomic considerations. Therefore, these result in deleterious effects on human bodies such as lordosis and kyphosis. In fact, it has been overlooked due to the lack of technical and scientific supports. Also, in a mass production, it is hard to meet everyone's need. However, the well adapted ergonomic considerations should meet the needs for wide ranges of people. Indeed, in this study we will examine designing chairs in ergonomic perspectives and suggest additional controversial points and alternatives.

• Physical Therapy Korea
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• v.19 no.1
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• pp.46-55
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• 2012

The purpose of this study was to investigate the effect of the two different types of chairs on trapezius muscle activation during dictation tasks. Seventeen university students, each of whom were within ${\pm}1$ standard deviation of the mean Korean standard body size, voluntarily participated in this study. Surface electromyography was used to collect electrical signals from both the upper and lower trapezius muscles. Amplitude Probability Distribution Function (APDF) was performed to analyze the muscle activity. The findings of this study were 1) The backrest-point height of the auditorium chair and the height, length and width of the connected desk were shorter than what was suggested by the KS. Another difference was that the auditorium chair had a bigger angle of the backrest compared to the classroom chair. 2) Regarding within-subject effect the sole statistically significant difference was found between activation of the upper trapezius muscle. The upper trapezius muscle's %RVC in the APDF 10th-50th-90th percentile was statistically higher for participants sitting in the auditorium chair than for participants sitting in the classroom chair (p<.05). 3) There was an interaction effect between the 'two chair-types' and the 'two muscle-sides' in the APDF 10th-50th percentile (p<.05). 4) There was an interaction effect between the 'two chair-types' and the 'three gaze-direction' in the APDF 90th percentile (p<.05). The findings of this study indicated that maintaining a writing posture for a prolonged period of time in an auditorium chair significantly increased the left upper trapezius muscle activation compared to a classroom chair.

• 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.