• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.191-197
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• 2011

Lifting chair is a typical assistive product to aid for standing up and sitting down for persons with disability. It is particularly useful for the elderly persons whose muscular system is weakened by degenerative joint disease. This paper describes biomechanical assessments of lifting chair with hip-up function. In experiments we measured 3D motion and electromyographic(EMG) signal on the femoral muscle when subject performs the standing motion on the predetermined seat height. Based on assessment of the standing motion, we select the hip-up angle as 15 degrees to cover the relative femoral angle when EMG peak value is appeared. Using an implemented prototype lifting chair with hip-up function we perform standing experiments with five subjects. The experimental results show that the lifting and hip-up functions are effective to assist for standing up motion with less muscle force.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.93-100
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• 2010

In this study, user survey and some experiments were carried out to identify older adults' characteristics and needs for shower chair design. Firstly, the category and design components of shower chair were analyzed through product analysis. Secondly, older adults' needs for shower chair were identified through user interview and observation. Thirdly, experiment to measure older adults' motion, EMG, and body pressure while using shower chair was carried out and then older adults' characteristics for the use of shower chair were identified. Finally, the direction of design for shower chair was proposed to improve older adults' satisfaction.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.155-165
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• 2014

Objective: The aim of this study is to develop an office chair enabling to keep working at reclined sitting posture. Background: Sedentary workers are supposed to change the posture frequently during long hours of sitting. A reclined sitting position has been recommended to reduce disc pressure. But slumped sitting posture caused by the buttock sliding forward without any adjustment of back reclining is commonly observed. The worker seems to have tendency to change the sitting posture maintaining working condition. We assumed the reason to be their hands movement away from the working space when tilting backward. Method: Slide mechanism allowing seat to move forward was designed to maintain the hand position in working space during reclining. A prototype was manufactured and tilting motion was analyzed using motion capture system. Four experiment chairs were tested including the manufactured prototype chair and three other commercial chairs. Results: A backward movements of the hand position were 13.0mm, 101.7mm, 156.1mm and 139.3mm at the prototype chair, compared to chair B, chair C and chair D, respectively. And the movement was remarkably small at the prototype chair. Conclusion: The developed seat sliding chair allows back tilting maintaining hand position at working space. We expect the user tilting back more often than normal tilting chair during seated work. But further investigation is required to figure out the effectiveness of the developed chair using prolonged working hours. Application: The developed office chair directly affects commercialization.

• Journal of Korea Multimedia Society
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• v.15 no.6
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• pp.731-736
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• 2012

Latest digital cinema is getting more interest on recent days. The combination of visually immersive 3D movie with chair movements and other physical effects has added more enjoyment. The movement of the chair is controlled manually in these digital cinemas. By the analysis of the digital cinema's video sequences, movement of the chair can be controlled automatically. In the proposed method first of all the motion of focused object and the background is identified and then the motion vector information is extracted by using the 9-search range. The motion vector is determined only for the movement of background while the object is stationary. The extracted Motion information from the digital cinemas is used for the movement control of the chair. The experimental results show that the proposed method outperforms the existing methods in terms of accuracy.

• Journal of the Korea Society of Computer and Information
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• v.29 no.11
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• pp.277-284
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• 2024

In this paper, we propose a motion chair for flight simulators that can be precisely controlled using an FPGA. Existing motion chairs are unsuitable for a flight simulator environment, where natural position changes occur due to a sense of disconnection arising from simple mechanical motor operations. This paper, presents a motion chair suitable for flight simulation through BLDC motor control through the FPGA module. In addition, the operating load was improved by controlling the drive shaft and control device of the motion chair as a single driver. As a result of comparing the control signal and feedback data to evaluate the performance of the implemented system, it was confirmed that the change was stable without error in the target position, and the high-speed camera showed a natural flowing state change suitable for flight simulation. In the future, we plan to develop it into an integrated flight motion platform linked to virtual reality hardware.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.226-232
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• 2015

The aging of Korea is rapidly advancing in an unprecedented rate in the world. Indoor and outdoor safety accidents involving the elderly frequently occur, with elderly population increasing. Because the physical strength of elderly is decreased, it is necessary to develop devices that aid the everyday life of the elderly to prevent safety accidents. Among many activities, the motions of standing from and sitting on a chair require much physical strength from particular body parts, which causes an overload for particular body parts. To the elderly the repeating motion of standing from and sitting down on a chair is burdensome, because they do not have enough physical strength compare to young persons. As a result the elderly could be injured or falling during standing or sitting. Therefore, the development of a lift chair that considers the problems mentioned above is necessary to prevent the safety accidents of the elderly. The study designed a non-motorized lift chair that comfortably aids the standing and sitting down motion for the use of the elderly by reflecting the anthropometric data of the Korean elderly over 65 years old. Also the design was implemented to smoothly aid the standing motion by considering the knee angle of the elderly when standing. Because the regained strength to stand from a chair is depend on the knee angle. Unlike existing lift devices, this device utilizes a tilting mechanism that does not use electric power so that the product could be composed inexpensively than existing chairs released in the market.

• Journal of the Ergonomics Society of Korea
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• v.30 no.3
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• pp.395-401
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• 2011

Objective: This study examined the effects of working chair that was developed for farmers who work in grapevine's cluster thinning. Background: Agricultural work involves some of the nation's highest occupational risk exposures. Fruit cultivation has been recognized as one of the most hazardous crops in which to work. Grapevine cluster thinning task involve activities related to the main risk factors associated with upper limb work-related musculoskeletal disorders. Method: An experiment was designed to test the working chair. Six healthy male($25.8{\pm}4.9years$) were selected as the subjects for this study. Electromyography(EMG) was used to monitor the muscles activity, and Electro-goniometer was used to measure the ranges of motions of the elbow, trunk and knee. Subjective test was also carried out to examine discomfort body parts and their pain intensity. A grapevine's working space was built for the experiment and working chair was installed on it. In order to examine the muscle activity and range of motion, subjects used to the working chair for 30 minutes for each experimental condition. Another test without working chair was also performed for comparison. %MVC was used to quantify the level of muscle activity. Results: Decreases of muscle activity was found in all leg muscles and significant decrease of muscle activity was found in left Gastrocnemius. The range of motion of the trunk and knee also decreased when working chair used. Discomfort in lower back, thigh and shank region were reduced significantly. However, in upper limbs muscle activity tended to increase in working chair compared with conventional task. Conclusion: Improvement for cushion in seat back and pan required to reduce discomfort in buttocks. Application: Overall findings verified that the working chair might help to prevent upper limb and lower back MSDs based on the current study. These results can be practically used for work improvement for the grapevine growers to prevent MSDs.

• IE interfaces
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• v.15 no.1
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• pp.82-88
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• 2002

A study was conducted to develop user-centered kitchen furniture and workspace to reduce fatigue and to prevent housewives's disorders such as low back pain and musculoskeletal disorders from housekeeping activities. A questionnaire survey and interview were performed on 150 households those live in 32Pyung-type($105m^2$) apartment in Seoul vicinity. Also actual housekeeping activities for 24 hours were video-taped for further motion analysis. Results of the study revealed that housewives complained the inconvenience and small size of storage space, and worksurface height as the most important problems to be considered for redesign. And they responded, if feasible, sitting is preferred over standing while they are working. After adapting a sit/stand chair in the kitchen, a physiological experiment measuring heart rate(HR) and oxygen consumption($VO_2$) as response variables was conducted to examine the effects of sit/stand chair in reducing physiological demand during housekeeping activities. The results showed that working on sit/stand chair reduced energy expenditures by maximum of 30% and 31.0% in terms of HR and $VO_2$, respectively. Also rearrangement of kitchen structure based on motion analysis showed that walking distance during daily housekeeping activities can be reduced by 5.5% on the average. Hence, it is concluded that adapting a sit/stand chair in the kitchen could reduce fatigue and occupational disorders of housewives from extended housekeeping activities.

• Journal of the Ergonomics Society of Korea
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• v.30 no.2
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• pp.357-363
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• 2011

Objective: The aim of this study is to set the design direction of the lift chair's tilting seat for development. Background: Great attention has been shown to the development of senior friendly product, because of increasing elderly population rapidly in Korea. Therefore, we need to study on sit-to-stand(STS) motion of elderly systematically for developing lift chair that is one of senior friendly products. Method: In this study, we analyzed joint moment(knee, hip) and muscle activity (Erector spinae, Rectus femoris, Vastus lateralis) on STS motion of elderly(female, 60~70: 7) and young people(female, 20~30: 7) using 3 dimension motion capture camera, force plate, wireless EMG. Results: The results of muscle activity showed a similar trend but the results of joint moment were a lot of differences between the young and the elderly. Conclusion: The results of knee joint moment suggest the angle(10~30deg)-adjustable seat that can be better than to find the optimal seat's angle. Application: The method and results of this study are expected to develop senior friendly product and verification as well as be available to various application.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.139-144
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• 2010

Grape weeding work requires Ergonomics improvement, because it performs motion likely to cause Musculoskeletal disorders (MSDs) repeatedly and continuously. The object of this study was to reject workload in Grape weeding works raised MSDs with the Moving Rail-chair and Electromotive Scissors. As objective method of analysis, we used heart rate, EMG, RULA, REBA. As subjective method of analysis, we used questionnaire that indicate lethargy area of body, pain of muscle and bone. As a result, working with Moving Rail-Chair and Electromotive Scissors is lower heart rate and EMG than typical working. Also for the subjective evaluation, reducing of neck and shoulder movement makes improve workload.