• 한국전문물리치료학회지
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• 제11권1호
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• pp.19-25
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• 2004

The purpose of this study was to investigate the effects of backrests of varying degrees ($90^{\circ}$, $100^{\circ}$, $110^{\circ}$) on three abdominal muscles (upper rectus abdominis, external oblique, internal oblique) and back extensor activation during lower extremity exercise. The three different conditions during bilateral knee extention exercise were: (1) leaning on a chair with a $90^{\circ}$ backrest, (2) leaning on a chair with a $100^{\circ}$ backrest, (3) leaning on a chair with a $110^{\circ}$ backrest. Fifteen healthy muscle subjects (mean age=24.2 years [SD=2.96], mean height=175.6 cm [SD=7.46], mean weight=69.1 kg [SD=7.36]) with no history of neuromusculoskeletal disease voluntarily participated in this study. Electromyography was used to collect muscle activation, and the muscle activation was expressed as a percentage of maximal voluntary isometric contraction (%MVIC). Repeated one-way analysis of variance (ANOVA) was used to determine the statistical significance. The results were as follows: (1) upper rectus abdominis, external oblique, internal oblique activation measured significantly lower. (2) measured significantly lower when lower degree.

• 대한물리치료과학회지
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• 제24권3호
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• pp.12-17
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• 2017

Purpose: The purpose of this study was to investigate the effects of backrest angle on lower extremity muscle strength in adult. Method: This research results are based on 10 healthy adults. 10 degree difference in pelvic angle does not effect the cross-connection of the Hamstring muscles, and created 3 types of rest with 20 degree differences each at 95, 115, and 135 degree angles. Result: significantly difference in contractibility muscle strength in accordance to the 3 rake angle. Conclusion: After putting together all these results, since both the expansibility muscle strength and contractibility muscle strength of the knee showed to be effected as the backrest angle changed during isokinetic muscle strength assessment, further research should be conducted if similar research results as this study can be acquired at various angles.

• 대한기계학회논문집B
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• 제39권6호
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• pp.535-540
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• 2015

등판이 기울어지는 사무용 의자에서 등판 회전축 위치를 인체의 엉덩관절에 일치시키면 인체와 등판이 일체화되어 기울어짐으로써 사용성을 향상시킬 수 있다. 그러나 등판 힌지가 외부로 돌출되지 않도록 하기 위해 적용되는 핀인슬롯 조인트에서 기구적인 마찰이 발생해 등을 기울이고 세우는 동안 사용자에 영향을 줄 것으로 예상된다. 본 연구에서는 마찰 정도가 다른 조인트 부품으로서 슬라이더, 롤러 그리고 베어링 세 가지 유형을 적용하고, 등판 기울임 시 대비 복귀 시의 반발력 비율을 측정하였다. 실험 결과 베어링, 롤러, 슬라이더를 적용한 경우 등판 반발력 비율은$[{\pm}SD]$은 각각 $59.7[{\pm}10.3]%$, $47.2[{\pm}13.6]%$, $30.3[{\pm}18.1]%$로 나타나 베어링을 적용할 경우 마찰이 가장 작았다. 그러나 각 부품들은 생산단가 측면에서 차이를 보이기 때문에 부품 선정 시 마찰감소 성능뿐만 아니라 사용자의 주관적인 만족도를 함께 고려할 수 있음을 제시하였다.

• 대한인간공학회지
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• 제32권1호
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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.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.203-209
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• 2014

The rear center-hinge bracket is designed for supporting and folding the rear-seat backrest. This bracket needs to be strong enough to be able to rigidly hold the rear-seat backrest and to withstand luggage loads from the car trunk that are generated when a vehicle is driving on the roads. Particularly, current accident studies report that many serious occupant injuries occurred when the rear-seat back easily folded inward toward the car interior, driven by the luggage loads in the trunk. Given this fact, the robust design of the rear center-hinge bracket that mainly supports the rear backrest has become more important for providing customer safety and preventing high warranty and durability problems. However, none of the studies have emphasized its significant role and considered its robust optimization. Therefore, this paper presents how the hinge-bracket design is optimized based on an application of the finite-element method coupled with the parameter design using Taguchi's design experiment. Finally, Taguchi method's application optimizes a robust center-hinge bracket that shows more rigid performance although it has lighter weight and thinner thickness.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.178-182
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• 2000

The purpose of this study is to investigate the train seat dimensions suitable for keeping comfortable postures. We designed a special experimental seat of which the lengths and angles are adjustable separately. Seat dimensions keeping subjects comfortable were measured for the restricted posture and the extended posture. The significant differences of dimensions fur two postures were analyzed, and the differences were found on backrest-seatpan angles, length of backrest and so on. The dimension differences fur the levels of height and weight were also found out. Some dimensions were correlated with subjects' height and weight..

• 융합신호처리학회논문지
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• 제19권3호
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• pp.104-109
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• 2018

심전도와 심탄도를 무구속적으로 동시에 측정하는 시스템을 개발하였다. 제안된 시스템은 의자의 보조 등받이에 설치되어 맥파전달시간(PAT), Pre-ejection period (PEP) 등의 심혈관계 역학 정보를 일상생활에서 무구속적으로 측정하는 것을 목적으로 개발되었다. 본 연구에서는, 의자의 등받이에 부착된 용량성 능동전극과 용량성 접지를 이용한 간접접촉 심전도 (IDC-ECG) 측정 방법에 의해 무구속적으로 심전도를 측정하였으며, 등받이에 부착된 EMFi 압력 센서를 사용하여 무구속적으로 심탄도(ballistocardiogram)를 측정하였다. 제안된 시스템으로 심전도와 심탄도가 무구속적으로 동시에 측정됨을 확인하였으며, 측정된 심탄도는 피검자 사이에서 일정한 패턴을 보이는 것을 알 수 있었다. 또한 심전도의 Q파와 심탄도의 첫 번째 첨두간의 시간차가 pre-ejection period와 높은 상관관계를 보이는 것도 확인할 수 있었다. 이 연구에서 개발된 시스템은 심혈관계의 다양한 지표(심전도, 심박수, PAT, PEP 등)를 무구속적으로 일상생활에서 측정할 수 있음을 보였다.

• 한국엔터테인먼트산업학회논문지
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• 제14권7호
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• pp.469-476
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• 2020

본 연구는 등받이 유무에 따른 하지 운동프로그램이 허리통증이 있는 대학생에게 미치는 영향을 알아 보기 위해 균형능력, KODI, VAS 검사를 이용하였다. 광주광역시 소재 K대학교 학생 32명을 대상으로 4주간 탄력밴드를 이용한 하지 운동프로그램을 진행하였으며 등받이의 유무에 따른 집단 별 16명씩 무작위로 선정하여 진행하였다. 균형능력과 KODI 점수에서는 집단과 시간에 의한 상호작용이 없는 것으로 나타난 반면 VAS 점수에서는 집단과 시간에 의한 상호작용이 나타났다. 또한 두 집단 모두 중재 후에 균형능력, KODI, VAS 점수에서 유의하게 증가하였다. 따라서 등받이 유무와 상관없이 의자에 앉아서 시행하는 하지운동 프로그램이 오랜시간 앉아서 생활하며 허리통증이 있는 학생과 직장인에게 일상에서 쉽게 할 수 있는 운동 프로그램으로 적용하는 것이 필요할 것으로 생각된다.

• 로봇학회논문지
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• 제4권3호
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• pp.243-249
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• 2009

In modern society, people spend most of their time on various types of chairs. However, it is not easy for a designer to design a comfortable chair because satisfaction with the chair depends not only on the quantitative elements such as size, but also on the qualitative element such as the user's feeling. To deal with these problems, there have been many studies on designing ergonomic chairs. This paper proposes the haptic-aided design (HAD) system to design an ergonomic chair. Based on the HAD system, the designer can experience whether the chair is comfortable or not through the haptic device, and also can modify the design parameters instantaneously. The haptic chair capable of controlling the design parameters in real time was proposed as a haptic simulator. The controllable parameters, such as seat height, reclining angle, stiffness of the backrest, and so on were selected based on the previous research related to ergonomic chairs. The proposed methodology will help reduce the development cost and time by replacing the process of making the real mock-ups and prototypes with the haptic chair.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.171-180
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• 2000

This paper deals with the whole-body vibration and ride quality evaluation in the vertical direction. The responses of the floor, hip, back, and head in four subjects were measured for various seats when the floor was excited by random vibration with r.m.s of 1.2m/s2 in the vertical direction. In the transmissibility between the hip and floor, the fundamental mode is observed at 4.4 Hz. In the transmissibility between the head and floor, the fundamental mode at 4.4Hz and the second mode at 7.6Hz are observed. It is shown that the head motion is 41% larger than the hip motion and the response of female subject is larger than that of male subject. The response without backrest also was compared with that with backrest. From these human responses ride quality of five seats were evaluated by the ride value such as transfer ration having frequency weighting function is the statistical sense. It is observed that the seat having high damping property can reduce the most acceleration exposed to hip in the statistical sense for all ride valves, while the seat having different seat spring doesn't show statistical difference.