• 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.

• 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.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.605-611
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• 2011

Objective: The aim of this study was to investigate the influence of seat heights for optimizing the ingress/egress performance in the elderly people. Background: Recently elderly users have been increasing in number and the ease of ingress/egress of the vehicle becomes an important issue. Method: Seven elderly subjects participated in this study(age: 71.7${\pm}$3.6yr, height: 167.7${\pm}$5.4cm, weight: 68.1${\pm}$11.5kg). Each subject performed the sitting and rising task from comfortable seated position on the chair under the following conditions: (1) with a lumbar support and (2) without a lumbar support. We measured EMG activities of seven muscles(tibialis anterior, soleus, gastrocnemius, vastus lateralis, rectus femoris, biceps femoris and erector supinae) and ranges of motion in lower limb during sitting and standing from three different heights (400mm, 500mm and 600mm from ground) of slide-up seat. Results: Muscle activities and angular movements of hip and knee joints during standing-up and sitting-down with a high seat height(600mm) were reduced mean 30.4% in extensor muscles, 57.11% in flexor muscle, 18.74% in erector muscle and 31.0% in joints compared with a low seat height(400mm). Conclusion: Muscle activities and joint movements in hip and knee were reduced when rising/sitting from a high seat height(600mm) compared with a low seat height(400mm). Application: This study can be used to design vehicle that are easy to get in and out of by older peoples with or without impairments.

• PNF and Movement
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• v.9 no.1
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• pp.31-38
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• 2011

Purpose : Sit-to-stand (STS) is one of the important activities of daily living (ADL) and each of its parameters is used frequently. This study aimed to examine the influence of different seat height on performance time and floor reaction force strength during an STS movement. Methods : Fifteen young-adult male subjects participated in this study. The subjects were divided into three groups based on lower leg length. Subjects performed an STS movement twice from chairs at height adjusted by the lower leg length of each subject. To examine the influence of the chair seat height, ground reaction forces during a STS performed with 3 chair heights adjusted to each subjects lower leg length were compared. Results : Vertical ground reaction force and time during an STS movement were measured to evaluate. Parameters regarding ground reaction force were selected for analyses. Significant differences were found in ground reaction force at G1 was greater than G2 and G3. Conclusion : The STS movement achievement strategy differed since chair seat height changes relatively by the difference in lower leg length. When conducting the ability to achieve STS movement rating test, chair seat height considering each subject's lower leg length may be needed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.2
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• pp.146-153
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• 2014

This study investigates the effects of seat-design elements such as seating arrangement, shape, and height on speech privacy in high-speed trains. For the evaluation of speech privacy, acoustic simulation software was used to reproduce room acoustical conditions in passenger cars on the basis of in-situ measurement data. The influences of speech source directivity and source height on privacy distance ($r_P$) were investigated, and it was found that $r_P$ determined using an omni-directional source was relatively shorter than that determined using a directional source. It was also found that $r_P$ decreased when the source height was lower than the height of the seat-back because the seat-back blocked the propagation of speech from the sound source. The effect of seating arrangement was not significant when comparing the vis-a-vis seating and one-side seating arrangements. In addition, among the alternative seat-designs, the seats that block the space between the seats and cover the space near the ear were found to show significantly enhanced speech privacy in high-speed train passenger cars.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.99-105
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• 2004

The car seat head restraint is used for neck injury(whiplash injury) prevention in rear end impacts. The purpose of this study was to evaluate the seat head restraints for the total number of 34 domestic cars. H-POINT machine and HRMD(head restraint measuring device) were applied to measure backset(the distance between head and seat head restraint) and height(height gap between head and seat head restraint). For tendency study of driver's head position, we took the 320 driver's pictures in the street. As results, There were only five percent drivers in good and acceptable zone. For car seat head restraint system, the results was 9 cars for good zone, 10 cars for acceptable zone, 9 cars for marginal zone and 6 cars for poor zone were evaluated. For a precise evaluation the of whiplash injury, detailed FE neck model will be developed and the clinical database should be constructed for model validation.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.61-72
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• 1996

In this paper, the driver seat comfort of eight automobiles was studied. The joint angles and anthropometric data of eleven subjects sitting on the seating buck were investigated using the instrument devices such as scale, goniometer, vernier calipers, protractor, Martin set. The joint angles of the most comfort posture were found by experiment and compared with previous studies. The anthropometric data of Korean(1992 year surveys) and American(1970∼1974 year) were applied to evaluate the driver seat layout of Korean automobile. The joint angles of the most comfort posture for eleven subjects were obtained with experimental results. The joint angles were agreed with reference angles. The driver seat layout was not suited to seat length and acceleratorseatpan forward distance in 5 percentiles female, pedal separation and seatpan-roof height in 95 percentiles male. Korean automobiles were not suited to seatpan length and steering wheelseatpan clearance, floor-roof height for American 95 percentiles male. The driver anthropometric dimensions were more suitable to middle size than small size automobiles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.961-962
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• 2012

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.54-61
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• 2013

Although typically classified as AIS 1, whiplash injuries continue to represent a substantial social problem with associated costs estimated at over $1 billion annually. The primary objective of this study was to determine the effects of seat positions(seatback angle, headrest height) on risk for whiplash injury in very low speed(${\Delta}V$=4~10km/h) rear-end impact. To accomplish this, rear impact seat carriage tests and simulations were conducted using the BioRID-II dummy seated in a mass production seat, which allowed for the adjustment of seatback angle and headrest height. Neck injury criteria(NIC, Nkm) were then compared for different ${\Delta}V$ and seat positions.

• Journal of the Ergonomics Society of Korea
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• v.36 no.2
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• pp.69-86
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• 2017

Objective: The present study is intended to develop an improved bus seat armrest design by evaluating various bus armrest designs from ergonomic aspects. Background: An ergonomic armrest design which considers the sitting postures and body shapes of passengers can improve the convenience and comfort of a bus seat. Method: Subjective satisfaction of each of five design dimensions (length, width, height from seatpan, shape, and angle) was evaluated for seven bus seat armrest designs in various sizes and shapes by 58 participants (28 males and 33 females) using a 7-point scale (1: very dissatisfied, 4: neutral, and 7: very satisfied). Improved bus seat armrest designs adjustable in length and rotatable to the left or right (sliding and rotating armrest, SRA) with a concave, flat, or convex shape of the upper part were developed by considering the preferred design features and the body size and shape in sitting posture and needs of passengers and then compared with a conventional armrest. Results: A bus seat armrest with a wide width (40~50mm), a long length (360mm), a lower height (213mm), and a curved shape was found significantly preferred in terms of comfort. The proposed armrest designs (SRA-convex, SRA-flat, and SRA-concave) improved satisfaction by 46~62% for length suitability, 184~216% for width suitability, 205~214% for angle suitability, 138~181% for contact area suitability, and 49~64% for height suitability, 138~174% for comfort, and 93~111% for overall satisfaction. Conclusion: The preferred design features and passengers' needs of bus seat armrest were identified and the SRA designs were recommended for better usability. Application: The ergonomic design process of bus seat armrest employed in the present study can be applied to designing armrests in various vehicles for better convenience and comfort.