• The Journal of Korean Physical Therapy
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• 제30권3호
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• pp.96-99
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• 2018

Purpose: The purpose of this study was to determine the effects of a chair backrest on respiratory function after prolonged sitting. Methods: Twenty-four young healthy subjects (12 males and 12 females) volunteered to participate in this study, and were equally allocated to a backrest (n=12) or a without backrest group (n=12). A spirometer was used to measure the respiratory functions of all subjects. Results: The chair with backrest group were significant difference in forced vital capacity (FVC), Forced expiratory volume in 1 second (FEV1), and peak expiratory flow (PEF) after sitting for 1 hour, compared with chair without backrest group (p<0.05). The chair with backrest group showed a significantly decreased in FVC, FEV1, and PEF. Conclusion: Using a chair without a backrest may help to reduce lung function deterioration as compared with a chair with a backrest.

• 대한간호학회지
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• 제36권2호
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• pp.353-360
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• 2006

Purpose: This study was done to investigate the effects of backrest elevation of 0 degree and 30 degrees that minimize the risk of increasing ICP when CVP is measured. Methods: Subjects were sixty-four patients who stayed in the neurosurgical intensive care unit after brain surgery at two university-based hospitals. CVP, blood pressure, heart rate and ICP were measured along with position changes in order of backrest position with primary 30 degrees backrest position, 0 degree backrest position and secondary 30 degrees backrest position. For data analysis, one-group, repeated-measures analysis of variance design was used in SAS program. Results: Backrest elevations from 0 degree to 30 degrees did not alter the CVP without increasing the ICP. Therefore, 30 degrees backrest position is a preventive position without increasing ICP. Conclusion: 30 degrees backrest position might be appropriate for brain injury patients when CVP is measured.

• 한국운동역학회지
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• 제33권1호
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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.

• 한국전문물리치료학회지
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• 제12권4호
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• pp.26-32
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• 2005

This study was purposed to provide basic information on the correct application of a wheelchair's backrest angle by investigating the change in cardiopulmonary function according to backrest angle during propulsion. This study examined the effects of the wheelchair's backrest angle on the cardiopulmonary function by varying the angle to $0^{\circ}$, $10^{\circ}$ and $20^{\circ}$ with a propulsion velocity of 60 m/min. The experimental parameters were respiration rate, oxygen consumption rate and oxygen consumption rate/kg which were measured by a portable wireless oxygen consumption meter (COSMED, $K4b^2$). The results of the study were as follows: 1) There were no statistically significant differences in respiration rates due to changes in the wheelchair backrest angle (p>.05). 2) There were statistically significant differences in oxygen consumption rates due to changes in the wheelchair backrest angle (p<.05). 3) There were also statistically significant differences in the oxygen consumption rate/kg due to changes in the wheelchair backrest angle (p<.05). In conclusion, changes in the backrest angle of wheelchairs during propulsion influences oxygen consumption rates and heart rates, while respiration rates are not affected. Therefore, a training program for good seating and posture needs to be provided, and the wheelchair seating system should be equipped with the unadjustable-angle wheelchair to reduce the functional load on the cardiopulmonary system.

• 한국전문물리치료학회지
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• 제15권4호
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• pp.59-63
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• 2008

Pressure sores are painful and needless complications of critical illness. and manifest as a localized area of ischemic necrosis of tissue caused by pressure. This study analyzed the bed-backrest elevation system combined with hip and knee flexion for lower extremity lower pressure reduction. Eight healthy adults aged 21 to 26 years were recruited. The Body Pressure Measurement Mat of the TekScan system was used to measure the location and magnitude of the peak pressures on the body bed interface. The SPSS statistical package was used to analyze the significance of differences between the general bed-backrest elevation system and the bed-backrest elevation system combined with hip and knee flexion using the paired t-test. The result showed that the body-pressure of the lower extremity was more significantly reduced for the bed-backrest elevation system combined with hip and knee flexion ($26.6{\pm}4.3$ mmHg) than a general bed-backrest elevation system ($37.3{\pm}5.2$ mmHg) (p<.05).

• 대한물리치료과학회지
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• 제13권3호
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• pp.15-25
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• 2006

The purpose of this study was to investigate effects of different chair type (with backrest chair and without backrest chair) and pelvic position (anterior pelvic tilting and posterior pelvic tilting) on three abdominal muscles (upper rectus abdominis, external oblique, internal oblique) and back extensor activation during lower extremity exercise. The four different conditions during bilateral knee extension exercise were: (1) leaning on backrest chair with anterior pelvic tilting, (2) leaning on backrest chair with posterior pelvic tilting, (3) anterior pelvic tilting without backrest chair, and (4) posterior pelvic tilting without backrest chair. Fifteen healthy male subjects with no history of neuromusculoskeletal disease voluntarily participated in this study. Electromyography (EMG) was used to collect muscle activation data, and muscle activation data was expressed as a percentage of maximal voluntary isometric contraction (%MVIC). One-way repeated analysis of variance (ANOVA) was used to determine the statistical significance, and Bonferroni comparison was used as a post hoc test. The results of this study were the following: (1) Erector spinae activation was significantly lower in posterior pelvic tilting without backrest compared with that in leaning on backrest chair with anterior pelvic tilting. (2) Upper rectus abdominis activation was significantly lower than erector spinae in all four different chair type and pelvic tilting conditions.

• 대한인간공학회지
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• 제34권2호
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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.

• 대한기계학회논문집A
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• 제34권2호
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• pp.167-174
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• 2010

본 논문에서는 사무용 의자의 틸트 동작시 요추지지 기능과 등의 미끄럼을 평가함으로써 등판 회전중심의 최적 위치를 연구하였다. 이를 위해 인체와 의자로 이루어진 수학적 모델을 이용하여 틸트 동작 시뮬레이션을 수행하였다. 착석된 인체 모델의 측면 상에서 고관절 중심을 포함한 42개의 위치에 등판 회전축 위치를 설정하고 각각 시뮬레이션을 수행하였다. 또한 등판의 회전중심이 고관절에 위치한 의자 시작품과 좌판하부에 위치한 기존의 의자에 대해 동작분석 실험도 함께 수행하였다. 시뮬레이션 결과 등판의 회전중심이 고관절 중심에 가까이 위치할수록 틸트시 요추각도 변화량과 등의 미끄럼거리는 작아졌다. 한편 실험결과 착석자의 등과 등판사이의 이격변위와 미끄럼변위는 등판의 회전중심이 고관절 위치에 설계된 시작품에서 더 작게 측정되었다. 시뮬레이션과 실험결과로부터 등판의 회전중심이 인체의 고관절 위치에 가깝게 설계되면 틸트시 착석자의 요추를 효과적으로 지지해 줄 수 있음을 알 수 있었고 이때 착석자는 보다 편안하고 건강한 착석자세를 유지할 수 있다. 이 결과는 사무용 의자에서 등판 회전축 위치의 인간공학적 설계를 위한 가이드라인을 제공한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.376-380
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• 2000

All chairs are uncomfortable in the long run, but some chairs become uncomfortable more rapidly than others, and in any particular chair, some people will be more uncomfortable than others. Comfort will depend upon the interaction of chair characteristics, user characteristics, and task characteristics. In this study, we intend to design the comfortable office chair by investigating the anthropometric and biomechanical aspects for Korean. Therefore, we determine the design dimensions using the analysis of anthropometric data. With these dimensions, we design the chair mechanism of which backrest reclines with increasing chair pan declination. This mechanism allows the back to get adequate support at the correct level for any backrest declination. Also, the lumbar support in the backrest descends with increasing backrest reclining. By using this chair, a considerably better sitting posture can be obtained, and uncomfortable feeling and back pain may be prevented.

• 임상간호연구
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• 제14권3호
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• pp.117-128
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• 2008

Purpose: This study was conducted to examine the differences of knowledge, perception, and performance between the points of time before and after ICU nurses had the backrest elevation education. Method: The study subjects were 58 nurses at a medical and surgical ICU of one general Y hospital located in Seoul. They received the education, including backrest elevation guideline and related education materials. Data were collected from May 11 throughout August 12, 2007 with a structured questionnaire. Results: 1) There were significant differences in the mean scores of knowledge(2.21 at pre-education, 5.24 at post-education), perception(36.96 at pre-education, 53.36 at post-education), and performance(32.08 at pre-education, 43.51 at post-education), 2) There was a significant correlation between nurse's perception and performance (p=.000). 3) The nurse's perception regarding the importance of the back rest elevation education was significantly effective on their performance (p=.000). Conclusion: The backrest elevation education would contribute to improve ICU nurse's knowledge, perception and performance. The more the nurses would consider the importance of this education, the better they would perform the nursing intervention of backrest elevation.