• International Journal of Safety
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• v.4 no.1
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• pp.27-31
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• 2005

This study presents the relationship between the height of the chair and the force of deltoid muscle for pianist. The subject simulated playing the piano on the three different heights of the chairs. Digital camera was used to determine the angle of the joint of shoulder and elbow for 2-dimensional static link segment modeling in the sagittal plane. The deltoid, biceps and triceps muscles were considered to determine the muscle load. The results, compared to the force of deltoid muscle, are that the downward position of the higher chair produces significantly large force than the other two lower chairs. It can be caused by hunched shoulder with decreasing deltoid angle. In case of the upward position caused by the lower chair, even though the smallest force of deltoid presented, it was increased the force of elbow.

• Journal of the Ergonomics Society of Korea
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• v.14 no.2
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• pp.41-50
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• 1995

A field study was conducted to assess the preferred height and the range of discomfort recognition of school desks and chairs for students from elementary school to high school. For this study 43 male subjects and 44 female subjects in Taejon metropolitan area were surveyed. The result showed that the preferred height of chairs were found to be about 1.7cm higher than the popliteal sitting height, while the preferred height of desks showed no significant difference with the elbow sitting height which is known to be the ergonomically proper desk height. The threshold value between comfort and discomfort recognition of chair heigth was 1.88cm below the most preferred height and 1.79cm above it. The threshold value between comfort and discomfort recognition of desk height was 1.76cm below the most preferred height and 2.62cm above it.

• 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.

• Journal of the Ergonomics Society of Korea
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• v.9 no.2
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• pp.55-63
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• 1990

School children sit long on chairs in their classrom. Their posture is closely related to their chairs. Study of this relationship is very imporant for the health and education of school children. This report presents the results of study condcuted to determine the present status of classroom chairs and solve any problems identifede. The study involved 125 teachers in Seoul and Pusan, 175 fourth graders in Seoul, and 109 fourth graders in Puasn. The body dimensions of the school children and the dimensions of their chairs and desks were measured, and their postures while they studied at their desk were photographed. The following problems were identified as a result of the investigation: (1) Chairs are allocated to pupils according to their stature. (2) The teachers are not satisfied with the chairs and the method by which the chairs are allocated to their pupils. (3) The pupils complain of low seat height, narrow seat, and hard backrest, among other conditions. (4) The pupils select a chair one size larger than that suggested by their body size. (5) The poor posture of the pupils is traced to the seat height and sasyaku$(sitting height {\times} 1/3-1)$ of their chairs, their habit, their way of holding pencils, and lack of instruction by their teachers. The following recommendations are made to solve these problems: (1) Adjust the seat height and desk height to accommodate the pupils. (2) Provide both teachers and pupils with adequate knowledge of chails. (3) Provided each pupil with one desk and make the desk adjustable to sit his or her body dimensions. (4) Allocate a chair and desk to each pupil for his or her exclusive use. (5) Reserch and develop conversion tables that help to find suitable chails for individual pupils. New values of sasyaku and desk height, not specified in Korean Industrial Standards(KS), are proposed.

• Journal of the Korean Society of Safety
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• v.37 no.3
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• pp.79-85
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• 2022

The annual statistics on fall fatality consistently show the dangers of working at height. The "Occupational Safety and Health Act" specifies legal restrictions on work at height using a scaffold. However, there are different classes of work at height, and some rely only on ropes. This study proposes education, training, and institutionalization of the "rope access work system." In brief, it was concluded that accurate instruction on the knot method and the setting of some standards were important. For this, the use of an integrated work chair harness equipment was suggested.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.10-16
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• 2023

Objective: The purpose of this was to find out the muscle activity of the quadriceps femoris by gender when sitting on a chair while performing stairs gait (US; Up-stairs, DS; Down-stairs). Method: 13 male subjects (age: 22.00 ± 1.68 yrs, height: 174.85 ± 6.10 cm, weight: 68.15 ± 9.83 kg) and 15 female subjects (age: 21.17 ± 1.58 yrs, height: 168.20 ± 5.55 cm, weight: 55.73 ± 6.94 kg) participated in this study. The study used wireless three channel EMG. Results: In this study, there was no gender difference in quadriceps femoris activity during the US and DS periods, and there was no significant difference between the male group before and after postural maintenance during the US and DS periods. The quadriceps muscle of the female group also did not show a significant difference before and after US sitting. However, the vastus medialis muscle activity during DS in the female group was significantly lower after application than before application of maintaining a sitting posture (p<.05). There was no interaction effect between the 15-minute sitting position application and gender. Conclusion: Our results demonstrate that sitting in a chair affects the transient functioning of the quadriceps muscle in women. Therefore, emphasize the need for active rest when sitting in a chair for long periods of time.

• Fire Science and Engineering
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• v.10 no.4
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• pp.19-27
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• 1996

The objective of this research is to study on the upper layer temperature, interface height and flow regime in case of several furniture fires such as trashcan, chair, carpet, sofa, mattress and wardrobe as a fire starter in a residential room by performing the experimental studies. The upper layer temperature and the Interface height were relatively well agreed with the experimental results when the flow coefficient at the opening was 0.65-0.8 for the rectangular trashcan, 0.65-0.9 for the circular trashcan and chair, and 0.7-0.9 for the carpet, sofa, mattress and wardrobe. The interface heights for the seven furniture fires were around 1[m] maintaining steady state. However, at the time of the maximum temperature, the interface height was lowered to 0.25[m]-0.75[m] from the floor. The flow regime at the opening was filling and buoyant for the distributed fire, and for the concentrated fire it was filling and then quickly changed to flow, and the flow period was long. The descending speed of the interface height was proportioned to the inflammability of the furniture and the contact surface area with air. The time required to come down around 1[m] was within 1-3 minutes.

• Korean Journal of Occupational Health Nursing
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• v.12 no.2
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• pp.134-145
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• 2003

Purpose: The present study examines symptoms of VDT syndrome perceived by those nurses reviewing the application of health insurance at hospitals. This study also investigates those factor influencing on the experience of VDT syndrome among those nurses. Method: Data were collected through mail questionnaire survey in April, 2003. Of the 250 questionnaires disseminated, 214 questionnaires were finally analyzed using descriptive statistics and multiple regression analysis through SPSS/PC version 10.0. Result: Of the VDT syndrome, the musculoskeletal symptom score was highest, followed by ophthalmologic symptoms. The musculoskeletal symptoms were higher among younger nurses, having smaller space under the desk, and feeling uncomfortableness of the chair. The ophthalmologic symptoms were higher among those with a bachelor's degree, younger nurses, and those having a light reflection on the computer monitor, and those maintaining less than 40cm between eyes and the monitor. Higher dermatologic symptoms were observed among younger nurses and those using unclear monitor. The psychological symptoms were higher among younger nurses, those having a light reflection on the monitor, those unable to control the height of their chair, and those using uncomfortable chair. The overall symptoms were higher among younger nurses, those having a light reflection on the monitor, and those smaller space under the desk. Conclusion: Primary intervention should be given to those nurses with symptoms of VDT syndrome in order to regain health and prevent further aggravation of the symptoms. In particular, self-care behaviors of the nurses using VDT should be promoted with administrative support.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.128-136
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• 2023

Objective: The aim of this study was to investigate the effect of an 8-week closed kinetic chain typed Reformer and Chair Pilates exercise on static and dynamic lower limb alignment for healthy female adults. Method: Ten healthy young female adults without musculoskeletal injury history in last 6 months (Age: 29.3 ± 3.5 yrs., Height: 165 ± 3.4 cm, Body mass: 58.2 ± 5.4 kg) participated in this study. All participants asked to join the 8-week closed kinetic chain typed Reformer and Chair Pilates exercise, and the program was conducted for 60 minutes twice a week. Participants were asked to be measure a static Q-angle and performed free squat one week before and after the program. A 3-D motion analysis with 8 infrared cameras and 5 channels of EMG was executed in this study. The effectiveness of the training was evaluated by paired t-test, and the significance level was set at .05. Results: A significantly decreased in internal rotation angles was found at hip joint during free squat after the training. Also, significantly decreased in lateral rotation angles were found at knee and ankle joint during free squat after training. Finally, significantly decreased in muscle activations were found at adductor longus and peroneus longus during free squat after training. Conclusion: From results of our study, it is concluded that an 8-week closed kinetic chain typed Pilates exercise positively effect on lower limb alignment during dynamic movement.

• Archives of design research
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• v.12 no.3
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• pp.73-80
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• 1999

Many domestic users complain about severe pain to the waist, neck, and shoulder as well as work performance because the domestic chair design was developed with western anthropometry dimension and design criteria. Ergonomic design standards are needed for office chair design to reduce stress and poor physical posture for various user body types. In this study, we have suggested design dimensions recommended from previous studies and Korean anthropometry data. We also have reviewed users' preference dimension through measured subjects and analyzed differences between users' preference dimension and the previous design criteria to verify physical appropriateness. We evaluated general office chairs and adjustable chairs which can adjust to fit each person. we also analyzed how each design dimension was reached and affected the human body by evaluation of physical discomfort and comfort. We have found seat height is very important in a workstation. If the seat height is high, it effects the thigh. If width, height, and angle of the backrest are wrong, fatigue to the shoulder, neck, and waist, etc.. As a result of this experiment, we suggested that the height of a seat for Koreans be 425mm for the fixed type and 365-484mm for the adjustable type. Also other design recommendations were suggested in the thesis. In conclusion, our research will be very important in the database because it provides adjustable ranges to fit user's body types in the various design fields.