• 항공우주기술
• /
• 제8권1호
• /
• pp.207-214
• /
• 2009

본 연구는 미세중력 모델인 머리하향기울기(Head Down Tilt; HDT) 자세에서 운동 중저산소호흡이 심혈관계 반응에 미치는 영향을 알아보는데 있었다. 8명의 건강한 남성($23{\pm}2$ 세, 신장 $176{\pm}4$ cm, 체중 $75{\pm}8$ kg)은 4가지 조건(앉은 자세에서 정상공기 호흡: SN, 앉은 자세에서 13% 산소호흡; SH, HDT 자세에서 정상공기 호흡; SH, HDT 자세에서 13% 산소호흡; HH)에서 최대산소섭취량의 약 40% 운동강도로 15분간 싸이클링을 실시하였다. 심박수는 SH그룹이 SN그룹보다 높았고(p<0.05), HH그룹이 SH그룹보다 높게 나타났다(p<0.05). 혈중산소포화도는 SH그룹이 SN그룹보다 유의한 감소를 나타내었다(p<0.05). 이완기혈압(p<0.05) 및 평균동맥압(p<0.05)은 안정시 앉은 자세에서보다 HDT 자세에서 유의하게 낮아졌다. 체액변인인 Hb, Hct과 전해질 변인인 나트륨, 칼륨, 염소는 모든 그룹에서 차이가 나타나지 않았다(p>0.05). 대사적 변인 중 Lactate는 SH그룹이 SN그룹보다 유의한 증가를 나타내었다(p<0.05). 결론적으로, 저산소호흡과 자세의 이중자극은 심혈관계반응에 영향을 주지 않았다.

• 대한인간공학회:학술대회논문집
• /
• 대한인간공학회 1995년도 춘계학술대회논문집
• /
• pp.72-83
• /
• 1995

This study are to investigate the variations of the recruitment patterns of the nine lower extremity muscles, and to analyze the changes of the role assigned to each muscle during the seated posture. For exertion levels, the transition point of type F more unit of each muscle is inferred by analyzing the electromyogram at the seated postures. Also, for predetermined seated foot operations exertion levels, the recruitment pattern and the changes of the role assigned are identified in the continuous exertion, by analyzing the electromyogram change sdue to the accumulated muscle fatigue. The developed model can be used to design and to assess the pedals and foot-related equipments design.

• Industrial Engineering and Management Systems
• /
• 제3권2호
• /
• pp.140-150
• /
• 2004

Repetitive stress injury at the wrist has been reported as a common injury among visual display terminal (VDT) users (i.e., computer users). Adjusting a VDT workstation (computer table and chair) to maintain a correct seated posture while operating a keyboard is perhaps the most frequently recommended preventive solution. This paper proposes an analytical design methodology based on ergonomic design principles for recommending appropriate VDT workstation settings and layout of individual computer accessories on the computer table. The proposed design methodology consists of two interrelated phases: (1) determination of VDT workstation settings, and (2) design of computer accessories layout. Based on the information about the VDT user, dominant task to be performed, typing skill, and degrees of physical and visual interactions between the user and computer accessories, adjustment and layout solutions are recommended to allow having a correct seated posture while minimizing both physical and visual movements. The results from an experiment show that when adjusting the workstation and locating the computer accessories according to the recommendations given by the proposed design methodology, the user's hand movements can be significantly reduced.

• 한국전문물리치료학회지
• /
• 제21권3호
• /
• pp.11-19
• /
• 2014

The purpose of this study was to investigate the activity of the transverse abdominal muscle resulting from changed posture by measuring the thickness of the transverse abdominal muscle in a supine posture, a slouched sitting posture, and an erect sitting posture. The subjects of the study were 28 patients with cerebral palsy. All their transverse abdominal muscles at the end of inhalation were measured at supine, slouched sitting (S sitting) and erect sitting (E sitting) postures by using ultrasonography, and then their dynamic sitting balance was measured at S sitting and E sitting postures by using BioRescue. For the statistical analysis, the Kruskal-Wallis test and the Wilcoxon signed-rank test were used to compare the differences among each the postures. The results were as follows. The thickness of the transverse abdominal muscle when comparing the supine posture and the S sitting posture showed no statistically significant difference. But the E sitting posture showed a statistically significant difference as compared with the others. In addition, the dynamic sitting balance in comparing the S sitting and E sitting postures showed a significant difference. In conclusion, the E sitting posture has a more positive effect on postural control and balance than generally taking the S sitting posture, for the sitting posture of a patient with cerebral palsy. It is suggested that patients with cerebral palsy mainly experiencing a sedentary life or being in a wheelchair should be seated in the E sitting posture during their daily life, and it may be necessary to continue to monitor and manage the proper E sitting posture.

• 한국전문물리치료학회지
• /
• 제15권4호
• /
• pp.80-86
• /
• 2008

Cross-legged sitting postures are commonly assumed during computer work. The purpose of this study was to determine the effects of leg crossing on trunk muscle activity while typing at a computer. Trunk muscle activity was measured in three 8 different sitting postures, in random order. These posture were: normal sitting with a straight trunk and both feet on the floor (NS), upper leg crossing (ULC), and ankle on knee (AOK). The right leg was crossed onto the left leg in both cross-legged postures. Twenty able-bodied male volunteers participated in this study. Subjects typed on a computer keyboard for one minute. Surface electromyography (EMG) was used to record bilateral muscle activity in the external oblique (EO). internal oblique (IO), and rectus abdominis (RA). The EMG activity of each muscle in the NS posture was used as a reference (100% EMG activity) in relation to the two cross-legged postures. Muscle activity in the right EO. right IO, and left IO was significantly lower in the ULC posture than in the NS posture. In contrast, muscle activity in the right RA was significantly higher in the ULC posture than in the NS posture. Muscle activity in the tight RA was significantly higher in the AOK posture, as compared to the NS posture, whereas activity in the left IO was significantly lower in the AOK posture, as compared to the NS posture. The right-left muscle activity ratios in the EO and IO showed significantly different patterns in the cross-legged postures, suggesting that asymmetrical right-left oblique muscle activity had occurred.

• 대한인간공학회지
• /
• 제11권1호
• /
• pp.81-92
• /
• 1992

A two-dimensional static biochemical model of lower extremity in the seated posture was developed to assess muscular activities of lower extremity required for a variety of foot pedal operations. We found that the double linear optimization method that has been used for modelling articulated body segments does no predict the forces generated by biarticular muscles reasonably, so the revised double linear optimization scheme was used to consider the synergistic effects of biarticular muscles in our model, assuming that the muscle forces are distributed proportionally based on their physiological cross sectional area. The model incorporated three rigid body se- gments with six muscles to represnet lower extremity. For the model validation, three male subjects performed the experiments in which EMG activities of six lower extremity muscles were measured. Predicted muscle forces were compare with the corresponding EMG amplitudes and it showed no statistical difference. The model being developed can be used to design and assess pedal and foot-related tool design.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.522-528
• /
• 2000

Dynamic characteristics of seated human body were investigated by measuring apparent masses of eight different seating subjects exposed to vertical vibration. Two types of vibration signals - one is random signals over 1 to 30Hz having flat spectral density and the other is signals measured on seat rail in passenger car under driving conditions - were employed. It was found that the apparent masses are highly dependent on vibration level rather than type of the vibration signals. Based on the apparent mass measurements, a mathematical model of the human body in seating posture was developed by using genetic algorithm. Three-degree-of-freedom model was satisfactory in describing apparent mass of seated human body.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.241-245
• /
• 2003

When considering the effects of whole-body vertical vibration, it is valuable to have an understanding of the mechanical characteristics (mechanical impedance and apparent mass) of the body. This paper addresses experimental results carried out to investigate the characteristics of apparent masses fer 41 Korean. The apparent masses of the seated human body in vertical direction were measured during different experimental conditions, such as vibration excitation level (0.5-2 ms$\^$-2/ r.m.s). frequency range (1-50Hz), and upper body posture (relaxed, normal and backrest-upright). We showed the average of all subjects and all conditions and compared the results with ISO5982/DIS (2000).

• 한국기계가공학회지
• /
• 제20권9호
• /
• pp.97-103
• /
• 2021

In this paper, an omni wheel-based electric wheelchair is proposed that can achieve safe and convenient movement and can improve the convenience of living for mobility-impaired people who cannot move on their own. Generally, mobility-impaired people are afflicted with physical health issues such as pain and secondary body deformities because they often remain seated in wheelchairs for long periods of time. Hence, an electric wheelchair is required whose posture can be changed and whose size can be adjusted according to the user's body type. Such a wheelchair should also facilitate easy change of direction (even in a narrow space) for convenient movement. In this paper, an electric wheelchair featuring omni wheels is proposed that allows posture transformation and facilitates movement in a narrow space. It is believed that the proposed wheelchair can aid in enhancing the convenience of living for mobility-impaired people.

• 한국전문물리치료학회지
• /
• 제28권2호
• /
• pp.117-122
• /
• 2021

Background: Flat-back posture refers to a posture in which the pelvis is tilted backward, the lumbar spine is bent, the upper thoracic spine is increasingly bent, and the lower thoracic spine is straight. Given that most of the day is spent sitting, we need to develop exercise programs and devices that are suitable for people who spend less time exercising than sitting. Objects: This study investigated the effects of resistance footrest exercise on spine posture angles in visual display terminal (VDT) workers with flat back. Methods: We measured the upper lumbar angle (ULA) and lower lumbar angle (LLA) using a flexible ruler for the ULA and LLA. Then, after 1 week of resistance footrest exercise designed to strengthen the lumbar spine musculature, we measured these angles again. We measured each angle three times and then compared measurements from before and after exercise. Results: There were no significant differences in the ULA following the strengthening exercise, but significant differences were observed in LLA. Conclusion: The resistance footrest exercise strengthened the muscles affecting the pelvic and lumbar lordotic angles, and increases in the LLA were changed. This suggests that the role of the lower lumbar spine in the lumbar lordotic curve is greater than that of the upper lumbar spine. In addition, considering the contemporary tendency to lead fairly sedentary lives, these results indicate that exercising while seated can be effective.