• Journal of Korean Institute of Industrial Engineers
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• v.25 no.4
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• pp.459-465
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• 1999

A new-concept VDT workstation chair with adjustable keyboard/mouse support was proposed to minimize physical discomfort and the risk of cumulative trauma disorders (CTDs) at work sites in this study. First, a three-dimensional human modeling tool $(SAFEWORK^{(R)})$ was used to design the new chair satisfying the anthropometric specifications of Korean population. Second, based upon the result of 3-D graphical simulation, a mock-up chair was constructed with an adjustable keyboard/mouse support directly attached to the chair body. Third, muscle fatigue and subjective discomfort were measured to evaluate the newly developed chair. An experiment was conducted to compare the new workstation chair to the traditional computer chair without keyboard/mouse support. Six volunteer subjects participated in six one-hour word-processing sessions with two different chairs and three different postures. Statistical results indicate that the new-concept VDT chair generally improved subjective comfort level and reduced fatigue in finger flexor/extensor and low back muscle. In conclusion, this new VDT workstation chair is expected to reduce physical discomfort and prevent occupational CTD problems in the long run. Implications of the new design and suggestions for the further development are also addressed.

• 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 Korea Furniture Society
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• v.10 no.2
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• pp.9-16
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• 1999

The goal of the present study is to develop the Human Interface Elements(HIE's) for evaluating the physical suitability of office chairs. HIE is generally defined as the physical characteristic of manufacturing goods, and it is closely related to the body dimension of a user and environment that it is used. In the present study the design elements of a chair were investigated, and from here, HIE's of office chair were developed based on relatedness of the design components, the physical characteristics of users, and characteristics of an environment that it used. As a result, components of a chair were classified as 6 major parts: Seat pan, back rest, arm rest, function control unit, seat supports and whole system. 43 HIE's were extracted from there 6 components. Also, the method for measuring HIE were developed.

• Korean Journal of Acupuncture
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• v.35 no.2
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• pp.82-90
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• 2018

Objectives : The purpose of this study is to investigate the effect of acupoint and meridian muscle massage given by automatic massage chair. Methods : We recruited 30 patients with back pain who met inclusion criteria. Two weeks were given as a waiting period, and the massage intervention was applied 12 times for 4 weeks. The programmed automatic massage chair was used to provide effective stimulus on acupoints and meridians for 20 minutes. We used Visual analog scale(VAS) and Korean Oswestry Disability Index(KODI) to quantify pain and function. We also recorded patients' all of vital signs and abnormal reactions during the trial to asses to assess safety. Results : Two participants dropped out due to personal reasons and 28 participants completed the clinical trial. We found that the degree of back pain (VAS, KODI) decreased significantly after the trial. As a result, VAS score decreased from $6.44{\pm}0.85$(Visit 2) to $4.59{\pm}1.52$ (Visit 14)(p<0.001), and KODI score was also reduced from $14.79{\pm}5.13$(Visit 14) to $9.04{\pm}4.52$ (Visit 2) (p<0.001). Also, we did not find any adverse effects in this study. Conclusions : We found that the acupoint and meridian muscle massage can effectively decrease back pain. This proves that the massage program designed by Korean medicine can be a good option to patients with back pain. However, further study with controlled design is still needed to verify its effectiveness.

• Journal of Korean Society of Neurocognitive Rehabilitation
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• v.10 no.2
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• pp.19-26
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• 2018

Many people do not realize that they have poor neck posture. Incorrect forward head posture can lead to turtle neck. This aim to development of specific chair to reduce tension and other symptoms of turtle neck posture. This turtle neck syndrome adjusting chair is a chair that supports the hip and shin of a person to help them correct their posture. It is consisted of the shin support that supports the shin in an angle and the hip support that supports one's hip while the shin is supported at an angle, the main frame that has the two of them connected and the fluid seat that is joined at the top of the hip support and reacts accordingly to the shape of the hip. This is a posture correction chair which has the fluid seat that provides unstable hip support so that it can allow a person to realize their posture from the constant stimulation about the posture. When one seats on the posture correction chair, their hip and shin are supported at an angle that straitens their back, and as their back is straightened, their shoulders and chest are opened, and the neck is positioned at the middle to help them correct their posture. An unbalanced posture causes discomfort to the person seated at the chair, and the person sitting on the posture correction chair will continuously adjust his/her posture to balance the hips to keep the correct posture. Through this process, the person shall adjust his/her left and right posture, ultimately increasing the effectiveness of posture correction. A future collective study on the continuous posture correction of people having turtle neck syndrome using this posture correction chair is required.

• Journal of the Ergonomics Society of Korea
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• v.33 no.4
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• pp.267-279
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• 2014

Objective: The objective of this study was to define the Dynamic Sitting (DS) through trend analysis and research on the Dynamic Chair (DC) and applied technologies. Background: The effects of changing posture on the human body have been studied to find out healthy sitting postures. It is believed that changing posture is effective in reducing disc pressure on spinal cord and preventing back pain and musculoskeletal disease. But, the definition of DS and trends of DC have not been researched yet. Therefore, trend analysis of DC and its applied technologies are required to define dynamic sitting posture. Method: We researched the type of occupant postures from previous studies. And then, sitting behaviors were classified into three types; (1) sitting and standing, (2) working and studying, (3) taking a rest. Results: Variety shapes of DC and applied technologies were found out. From the result, the trend of DC and applied technology were summarized from three perspectives. ; (1) changing the chair functions according to user's intention, (2) conversion of dynamic chair technologies to office chair mechanism, (3) enables the user to change their sitting posture without operating control device. Conclusion: From this study, we defined dynamic sitting posture and analyzed the trend of DC and its applied technologies. This result might be used to develop an office chair for healthy sitting. But further investigation is required to figure out the technologies and functions for development of healthy chair. Application: The results of the publishing trend analysis might help to determine design concept of office chair.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.20-36
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• 1993

Work-related low back pain is one of the major factors that cause the loss of working power especially in actively working age, therefore controlling the work-related low back pain is one of the major issues in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the efficient control program of the work-related low back pain. The subjects were male workers employed at the manufacturing industry in Pusan with longer than 6 months' working duration. The data was collected by self-reported questionnaire and interview from May 1 to October 31,1992. The contents of questionnaire were as follows:. the experience of low back pain within the recent one month, general characteristics(age, marital status, education level, religion, regular exercise), physical characteristics(height, weight), employment status(working duration, daily working hours, rest during work, satis(action fur the job), type of work and working environments(posture, forward bending, lifting and movement, satisfaction for table and chair). The result was analyzed for 608 entire respondents by case-control comparative method. The number of cases was 152 with a history of work-related low back pain, so the relative frequency of self-reported work-related low back pain was 25.0%, and the number of controls was 344 without any history of low back pain. As a result, two characteristics of the employment status(working duration, satisfaction fur the job) and all characteristics of type of work and working environments showed a statistical significance between the case and control groups(p<0.01). The Oddb ratios of these variables for Work-related low back pain were calculated. They were 7.88 for the satisfaction fur chair, 7.86 for lifting and movement,3.31 for satisfaction for table, and 2.22 fur bending forward(p<0.01). And for the multivariate logistic regression analysis confirmed that unsatisfaction for table was independent risk factor for Work-related low back pain. In summary, though this study was based upon the self-reported questionnaire and the subjective complaints, the satisfaction for chair, lifting and movement, satisfaction for table, and bending forward concerned with the type of work and working environments were considered as the main factors causing the work-related low back pain, and the work-related low back pain may be preventable by the ergonomic control of these factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.476-482
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• 2017

This study examined the effects of the seat height of a chair on the muscle activity of the erector spinae and rectus abdominis. Thirty healthy subjects were asked to sit on chairs at three different seat heights. The muscle activities of both the erector spinae and rectus abdominis were measured by surface electromyography. The data were analyzed by repeated one way ANOVA and the muscle activity was compared according to the seat height. The alpha level was set to 0.05. The results showed that the muscle activities of the erector spinae were not significantly different among the three seat heights. The muscle activities of the rectus abdominis were significantly different among the three seat heights. Both the rectus abdominis muscle activities were significantly greater in the low seat height than the other seat heights. These results showed that the seat height of the chair affects the muscle activities of the rectus abdominis muscle, leading to musculoskeletal pain, such as low back pain. Therefore, the seat height of a chair with a correct sitting position is important for preventing musculoskeletal pain.

• Archives of design research
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• v.15 no.4
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• pp.177-188
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• 2002

A thousands of chairs have designed from the Victorian era to the present. Thonet's Nol4 chair in 1859, Wright's high-back chair in 1904, Ritveld's red/blue chair in 1917, Breuer's Wassily chair in 1925, Aalto's Paimio chair in 1932, Eames's DAR chair in 1948, Piero Gatti's Sacco chair in 1969, Starck's Von Volgelsang chair in 1984, Stumpf's Aeron Chair in 1992, Little's 'Coat of arms' chair in 1994 - the list of architects who have seized the opportunity to express their theories in the design of a chair is seemingly endless. Architects such as Machintosh(1868-1928), Wright(1807-1959), Aalto(1898-1976) included chairs within their artistic schemes for interiors and buildings. But as the manufacture of chairs moved away from the domain of the craftsman towards that of the industrial process, architects were also ideally positioned, with their background knowledge of engineering, to pioneer innovative chair design within the constraints of modern manufacturing technology. Beyond matters of function and structure, the fundamental worth of chairs, past or present, lies in their communication of attitudes, ideas and values. The persuasiveness of a chair depend on the clarity of its rhetoric. Chair has become an ideal medium for designers to make their visual statements and construct their individual manifestos. In chair design there is a ping-pong game played out between absurd and useful design, and this game is one way in which the design profession explores itself.

• Journal of Korean Physical Therapy Science
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• v.3 no.4
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• pp.171-179
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• 1996

This study was conducted to investigate on the standardization of wheel chair for Korean in the twenties college students. Study population included 200 students in Andong junior college from September 25, 1996 to October 16, 1996. Basic measurements for wheel chair production were carried out A(from behind calf to rear of buttocks), B(from the popliteal fossa to the bottom of the heel), C(from the bottom of the elbow to the seating surface), D(from the seating surface from to midseapula), E(across the hip at widest point). The results are as follows. There was a statistical significance between male and female body dimension measurements in the A(p=0.0018), B(p=0.0001), E(p=0.0001), the other side not significance of C(p=0.1193), D(p=0.8467). The standard dimension of wheel chair included seat depth 40.6 cm, seat height 48.1 cm, arm height 25.8 cm, back height 35.7 cm, seat width 39.6 cm in the twenties male college students and in female case included seat depth 39.3 cm, seat height 45.2 cm, arm height 26.5 cm, back height 35.8 cm, seat width 41.2 cm.