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착석자세 모니터링 시스템 개발을 위한 착석자세 추정 연구
형준호(Joon-Ho Hyeong),김사엽(Sa-Yup Kim),노종련(Jong-Ryun Roh) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Posture correcting system applies to the office chair that monitoring a sitting posture and send feedback to the user at real time basis. In the previous study, pressure sensors has been equipped both on the backrest and the seat pan to estimate sitting posture from five different posture types. In this preliminary study, posture detecting experiment has performed only using seat pressure sensors for reducing product cost. A subject was seated on the seat pressure mat and asked to change posture during measurement of the load at four divided sectors. The result says that the percentage of total force on seat pan compared with body weight (%BW) is a suitable index for assessing whether the users back lean against the backrest or not. Consequently, five different major sitting postures could be detected only using seat pressure sensors. The posture measuring technique is expected to be applied to the posture monitoring chair with resonable price.
형준호(Joon Ho Hyeong),정경렬(Kyung Ryul Chung),김사엽(Sa Yup Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Recently bicycle demands are increased due to environment, economic and health reason. Folding bicycle is getting more interested due to rapid urbanization and small housing space. In this study several types of folding bicycle were investigated and we focused on middle pivot folding bicycle features rear wheel part rotates downward and aligns next to front wheel. In the middle pivot folding bicycle, the pivot requires axial tilt from perpendicular line to sagittal plan in order to avoid interference between front and rear wheel during folding procedures. The purpose of this study was to describe the exact obliquity of the pivot so the rear and front wheel aligned parallel. The pivot obliquity was divided into azimuthal angle(φ) and polar angle(θ) using polar coordinate system. Parametric simulation was carried out using varied azimuthal and polar angles. Result says optimal obliquity is 130˚ of azimuthal angle and 4.3˚ of polar angle which are directly affected by the angle of head tube(α), the rotation angle of rear wheel part(β) and the perpendicular distance from pivot point to head axis.
형준호(Joon-Ho Hyeong),김사엽(Sa-Yup Kim),노종련(Jong-Ryun Roh),정경렬(Kyung-Ryul Chung) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
The hinge mechanism on folding bicycle is one of the most important design factors, which allows the bicycle frame to fold and to make size reduction. The hinge mechanism contains clamping mechanism which controls locking and release of frame rotation. Hinge and clamping mechanism is critical to the cycling safety and it affects usability and appearance also. But the study on the bicycle hinge mechanism has not been performed. In this study concept analysis of clamping function was carried out in order to enhance understanding of the hinge mechanism and three types of clamping mechanism were suggested. The force shifting procedure from the grasping force to the clamping force was analyzed and the amount of camping force was calculated at each types of mechanism. We expect this study contributes to the improvement of usability and appearance on folding bicycle.
형준호(Joon Ho Hyeong),김사엽(Sa Yup Kim),노종련(Jong Ryun Roh),박성빈(Seong Bin Park),정경렬(Kyung Ryul Chung) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.6
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[±SD]은 각각 59.7[±10.3]%, 47.2[±13.6]%, 30.3[±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. The location of the pivot between the backrest and seat pan of a reclining chair should be identical to the hip joint center to prevent unpleasant user experiences during tilting motion. However, mechanical friction occurs in the pin-in-slot joints that are installed under the seat pan as an alternative to the hinge joint. This reduces the reaction force between the backrest and the occupant"s back when reclining and returning to an upright position, which causes the occupant"s discomfort. In this study, bearings, rollers, and sliders were suggested as alternatives for the pin component, and the percentage of the reaction force on the backrest was measured while reclining the backrest and subsequently returning it to an upright position. The results show when bearings, rollers, and sliders were used for the pin-in-slot joint, the percentages of the reaction force were 59.7 ± 10.3, 47.2 ± 13.6, and 30.3 ± 18.1, respectively, indicating that the friction of the bearing was the lowest among the three pin components. Because the three alternatives have different manufacturing costs, synthetic judgment requires the consideration of not only mechanical friction but also user experience.
형준호(Joon-Ho Hyeong),노종련(Jong-Ryun Roh),김사엽(Sa-Yup Kim),정경렬(Kyung-Ryul Chung) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
A backrest pivot point should be identical to the hip joint center of human body so that occupants’ unpleasant experience in a reclining chair could be prevented. As seat pan and backrest support buttock and back keeping distance from hip joint, a couple of pin-in-slot joints rather than a pin joint must be applied to the backrest in order to match the center of rotation of backrest to the hip joint center. But mechanical friction occurs on the pin-in-slot joint, which makes decreased reaction force of backrest when tilting upright consequentially, occupants feel uncomfortable. In this study, bearing, roller, and slider was suggested for the pin components, and backrest reaction force(BRF) was measured between upright to maximally reclined tilting position. Results says that the backrest reaction force(BRF) was strong applying the bearing to the pin-in-slot joint while, it was the least when applying the slider. Because there is manufacturing cost difference among three alternatives consisted of several pin types, synthetic judgment requires considering not only mechanical friction but also occupant’s feeling and appearance.
사무용 의자의 종류에 따른 틸팅 동작의 거동분석에 관한 연구
정경렬(Kyung Ryul Chung),형준호(Joon Ho Hyeong),김사엽(Sa Yup Kim),노종현(Jong Ryun Roh) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The purpose of this study is analyzing commercial office chair that equipped with synchronized tilt mechanism which is characterized by the seat tilt synchronously with the backrest. The kinematic analysis of human-chair system during tilt was performed using dynamic simulation software. Five commercial office chair was selected and link system of tilt mechanism was modeled. Tilting angle of seat and backrest was calculated and the trace of eye, shoulder, hip and knee were analyzed by performing tilting simulation of human-chair system. There are various tilting characteristics among commercial office chairs and it affect on the human tilt motion. Human motion and comfort is priority requirements when designing office chair. And the tilt mechanism can be designed to support the aimed human motion.
정경렬(Kyung-Ryul Chung),형준호(Joon-Ho Hyeong),김사엽(Sa-Yup Kim) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.7
본 연구에서는 소형자전거의 핸들에 적용할 수 있는 전방 서스펜션을 제안하고 시뮬레이션을 통해 충격흡수 성능을 평가하였다. 서스펜션이 없는 경우, 기존의 전방포크서스펜션이 장착된 경우 그리고 제안된 핸들서스펜션이 장착된 경우 등 3가지 서스펜션 종류에 대해 인체모델을 이용한 주행시뮬레이션을 수행하여 각각의 완충성능을 비교평가 하였다. 시뮬레이션 결과 제안된 핸들 서스펜션의 경우 손과 머리에 전달된 가속도가 기존의 전방포크서스펜션이 장착된 경우보다 크게 측정되었지만 서스펜션이 없는 자전거의 경우보다는 현저히 작게 측정되었다. 이 같은 결과는 제안된 핸들 서스펜션이 상당한 완충성능을 보여주었으며 이는 경량화가 중요한 소형자전거에 적용이 가능할 것으로 보인다. In this study, a front suspension system, which is mounted on the handle itself, was suggested because of its light weight and cost efficiency. The shock absorption was evaluated for the three types of suspension models; non-suspension, suspension on front forks (existing model), and suspension on handle (suggested model). The human body model was used for performing impact simulation for comparing the shock absorption for the suspension models. The result of the simulation shows that shock absorption for the proposed suspension model was not as good as that for the front fork suspension model. Nevertheless, the shock absorption observed for the proposed suspension model was significant when compared to the non-suspension model. Consequently, the proposed suspension model could be applied to lightweight bicycles.