Kyung-Ryul Chung

Development of Tilting Chair for Maintaining Working Position at Reclined Posture

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.

The Effects of Different Backrest Pivot Positions on the Human Body During Reclining of the Office Chair

초록:본논문에서는사무용의자의틸트동작시요추지지기능과등의미끄럼을평가함으로써등판회전중심의최적위치를연구하였다.이를위해인체와의자로이루어진수학적모델을이용하여틸트동작시뮬레이션을수행하였다.착석된인체모델의측면상에서고관절중심을포함한42개의위치에등판회전축위치를설정하고각각시뮬레이션을수행하였다.또한등판의회전중심이고관절에위치한의자시작품과좌판하부에위치한기존의의자에대해동작분석실험도함께수행하였다.시뮬레이션결과등판의회전중심이고관절중심에가까이위치할수록틸트시요추각도변화량과등의미끄럼거리는작아졌다.한편실험결과착석자의등과등판사이의이격변위와미끄럼변위는등판의회전중심이고관절위치에설계된시작품에서더작게측정되었다.시뮬레이션과실험결과로부터등판의회전중심이인체의고관절위치에가깝게설계되면틸트시착석자의요추를효과적으로지지해줄수있음을알수있었고이때착석자는보다편안하고건강한착석자세를유지할수있다.이결과는사무용의자에서등판회전축위치의인간공학적설계를위한가이드라인을제공한다.Abstract:Inthisstudy,theoptimalpositionforthebackrestpivotofanofficechairwasinvestigatedbyevaluatingitsperformanceintermsofthelumbarsupportandslidingdistanceofthebackfromthebackrestduringtiltingmotions.The simulation was performed using a mathematical model, which included a human body and a chair. Forty-twobackrestpivotpointswereselectedonthesagittalplanearoundthehipjointofasittingmodel.Amotionanalysisstudywasalsoperformedusingaprototypeofanofficechair(A-type)withabackrestpivotlocatedonthehipjointofanormalKoreanmodelandatypicalofficechair(B-type)withitspivotlocatedundertheseat.Thesimulationresultsshowedthatboththelordosisangleandtheslidedistanceofthebackwereminimizedwhenthebackrestpivotwas positionedclosetothe hipjoint. Theexperimental results showedthat theslidedistanceandgapbetweenthesitterslumbarandthebackrestwassmallerwiththeA-typethantheB-type.Basedonthesimulationandexperimentalresults,itcanbeconcludedthatthebackrestcansupportthesitterslumbarareamoreeffectivelyasthepivotpositionfor reclining approaches closer to the hip joint. In this position, the sitter can maintain a comfortable and healthysitting posture. This paper presents the methods and guidelines for designing an office chair with ergonomicconsiderations.

A Trend Analysis of Dynamic Chair and Applied Technology

Objective: The objective of this study was to define the Dynamic Sitting (DS) through trend analysis and research on the Dynamic Chair (DC) and applied technologies. Background: The effects of changing posture on the human body have been studied to find out healthy sitting postures. It is believed that changing posture is effective in reducing disc pressure on spinal cord and preventing back pain and musculoskeletal disease. But, the definition of DS and trends of DC have not been researched yet. Therefore, trend analysis of DC and its applied technologies are required to define dynamic sitting posture. Method: We researched the type of occupant postures from previous studies. And then, sitting behaviors were classified into three types; (1) sitting and standing, (2) working and studying, (3) taking a rest. Results: Variety shapes of DC and applied technologies were found out. From the result, the trend of DC and applied technology were summarized from three perspectives. ; (1) changing the chair functions according to users intention, (2) conversion of dynamic chair technologies to office chair mechanism, (3) enables the user to change their sitting posture without operating control device. Conclusion: From this study, we defined dynamic sitting posture and analyzed the trend of DC and its applied technologies. This result might be used to develop an office chair for healthy sitting. But further investigation is required to figure out the technologies and functions for development of healthy chair. Application: The results of the publishing trend analysis might help to determine design concept of office chair.

A study on Estimation of Energy Expenditure using Horseback Riding Simulator

The horseback riding simulator, an exercise training machine providing a simplified horse riding motion has been developed for aiming at healthcare. The purpose of this study was to estimate the energy expenditure without measuring bio-signals using the simulator. The test protocol was consisted of increase up to maximal intensity(Motion 9) and decrease down to minimal intensity(Motion 4) during 25 minutes, and energy expenditure was measured by portable cardiopulmonary exercise testing analyzer. There were significant differences in energy expenditure according to each riding motion. The result will be able to estimate energy expenditure using motion level, exercise time, age and gender during the riding.

The Development of Interactive Ski-Simulation Motion Recognition System by Physics-Based Analysis

In this research, we have developed a ski-simulation system based on a physics-based simulation model using Newton`s second law of motion. Key parameters of the model, which estimates skier`s trajectory, speed and acceleration change due to skier`s control on ski plate and posture changes, were derived from a field test study performed on real ski slope. Skier`s posture and motion were measured by motion capture system composed of 13 high speed IR camera, and skier`s control and pressure distribution on ski plate were measured by acceleration and pressure sensors attached on ski plate and ski boots. Developed ski-simulation model analyzes user`s full body and center of mass using a depth camera(Microsoft Kinect) device in real time and provides feedback about force, velocity and acceleration for user. As a result, through the development of interactive ski-simulation motion recognition system, we accumulated experience and skills based on physics models for development of sports simulator.

Development of System Requirement Management Database System from User-centered Scenario

Abstract : In this paper, a new system requirement management tool and its application on the Urban Transit Maglev Project were introduced. In most R&D projects on complexity system such as transportation system, Systems Engineering(SE) activities are included on each project, and SE teams are using commercial computer-based tools to perform the SE activities. Even though SE tools help to manage huge data and documents on engineering efficiently, but well-designed functions of SE tools which support SE activities are not sufficiently used on the whole process of system engineering. In order to computer-based SE tools are to be effectively used on project management, most engineers who takes engineering and coordination roles, at least sub-project managers should be familiar to the tool and could be easily use it, but usability of commercial SE tools are very difficult for normal engineers with no experience on SE activities and SE tools. To overcome this difficulty, we developed a new system requirement management tool considering each user’s scenario on using engineering tools. The developed tool could not cover whole SE processes, but designed to perform requirement engineering such as system requirements(SRs) management, specification management, traceability management, SRs’ verification activity management and so on. All the entities on SR database are inter-connected by pre-recognized traceabilities, so even non-specialists on SE can easily browse the database and find entities concern, and linked information such as interacted entities, legal or engineering constraints, coordination documents, status of development and verification and so on. Also functions for SR verification tools, TPM(Technical Performance Measure) tools, DB searching tools with traceability, and report generation tools are included on the system.

Analysis of Functional Status and Determination for Improvement of ADLs: Korean Elderly

Muscular strength in the elderly is important factors deciding on functional state in daily lives, and functional state shows a health condition. Resistance training to prevent loss of muscle mass and muscle fiber atrophy due to aging can increase muscle mass and strength. Recently, resistance training to improve muscular strength and endurance has been actively researched. Resistance training increases activities of daily living and ability of the elderly, which makes healthy senescent. ADL/IADL is suitable for measuring health condition of the elderly. In this study, target muscles of resistance training were chosen through a correlation analysis between ADLs and elementary motion, and we presented a procedure to select target muscles and exercise equipments. This procedure consist of a survey method that were described detailed motion of ADL/IADL. So we should be to extract resistance training machine to improve functions of regarding fundamental motion. Result of study may improve daily life activities of the elderly through objectives and scientific approaches. Furthermore, it will be helpful to studies about various fields of the elderly.