• Journal of the Ergonomics Society of Korea
• /
• v.33 no.4
• /
• pp.281-287
• /
• 2014

Objective: The objective of the study is to develop a portable assistance device to help elderly users reduce strain on the knee and leg muscle while the elderly are standing up. Background: The pose of standing up from a chair is a basic movement, but the elderly often have difficulty standing up due to their weak muscles. We focus on designing a solution that helps the elderly reduce physical problems and support them standing up. Method: This study consists of three parts. Part I explores the way to reduce the refrain of leg muscle while standing up from a chair. In the process of structural development, we found that the moment is minimized when user pushes down the armrests due to a decrease in the force acting on the center of mass. In part II, a user test of 20 participants was carried out to rank the order of comfort of two stimuli: the chair with fixed armrests and the chair with the four-link mechanism that we created-in three different ways; (1) to stand up without touching armrests, (2) to stand up by pushing down on fixed armrests, and (3) to stand up by pushing down on armrests and being supported by the mechanism. To examine the statistically significant differences among the rank means, a Friedman test was conducted. In part III, we analyze the results of the user test and interview feedbacks, focusing on establishing a design strategy from UPO and visualizing it in 1:1 scale. Results: In part I, we decided to develop the four-link mechanism. The bottom is lifted up as the link rises. In part II, based on the rank data, we empirically found that UPO was assessed as the most comfortable during the stimuli. The thigh angle is smaller and the bottom of UPO is separated from a seat. In part III, after assessing the results and feedbacks, we created a visualization strategy for UPO: light, friendly, and novel. Conclusion: The portable and non-mechanical UPO comprises a four-link system that lifts the user's hips while standing. It can help users avoid knee and leg muscle strain. Its universal design considers the elderly's difficulties. Application: In a future study, combining light and durable material in UPO is expected to increase its usability. And this study is an opportunity to design various types of standing assistance devices.

• Journal of Power System Engineering
• /
• v.16 no.1
• /
• pp.24-29
• /
• 2012

Recently, in the movie theater, the special chair is installed to maximize the viewing effect of movies. It is structured to convey a vibrational stimulus to a specially-designated parts of human body by attaching a vibration transducer to a existing theater chair. This paper describes the analysis of the vibration transfer characteristic of a foaming sponge seat for the design of the special chair. We could not apply the structural analysis S/W because it is difficult to obtain the mechanical properties and damping coefficients of the various type sponges. And then we computed the transfer functions by the global curve fitting program based on experimental modal analysis. The experimental response results comparatively coincide with those by the global curve fitting program. We also could obtain the natural frequencies, the modal damping coefficient ratio, the modal vectors and the whole transfer functions. Therefore we could analyze the dynamic characteristic for design of foaming sponge seat.

• Journal of Drive and Control
• /
• v.20 no.1
• /
• pp.27-33
• /
• 2023

From the perspective of dental chair manufacturers, it is important to of localizing hydraulic system in order to secure market competitiveness. This study aims to develop the analysis model of a dental chair which overseas companies secure core technologies. The study follows the steps below. First, the component parts of the solenoid valve unit of a foreign leading company are analyzed and implemented in virtual environment. Second, dynamic behavior scenario is established based on solenoid valve signal chart provided by a foreign leading company. The analysis model is verified and its performance is analyzed using dynamic behavior according to each scenario. Third, a simulation is carried out to determine whether the cylinder velocity of designed hydraulic system surpasses 1cm/s as required by the design.

• Journal of Power System Engineering
• /
• v.17 no.6
• /
• pp.40-46
• /
• 2013

This paper describes the suggestion of the special seat with the auxiliary plastic member for movie theater chair. In the previous paper, we have reported on the development of foaming sponge seat with the auxiliary spring member. And we have confirmed that it was more effective on vibration transfer than the chair seat of foaming sponge only. In this study, we have examined the major design parameters needed in the development of a foaming sponge seat in which the mesh type plastic member are inserted to improve the vibration transfer effect of a chair seat. By applying experimentation to the prototype as well as the experimental modal analysis method, we made sure that the effect of the vibration transfer could be improved through the use of a mesh type plastic member as similar as the auxiliary spring member.

• Asia-Pacific Journal of Business
• /
• v.11 no.2
• /
• pp.45-60
• /
• 2020

Purpose - This study examines the impact of company ownership nature and of the dual role of CEO and board chair on R & D investment intensity, as well as the moderating effect of this dual role. Most previous research focused on the impact of the dual role of CEO and board chair on firm performance. Design/methodology/approach - This study uses A-share companies listed on the Shenzhen and Shanghai stock exchanges in China from 2008 to 2017. The univariate and the multivariate regression analysis were hired In order to analyze the data. Findings - The results show that there is a significant negative relationship between state-owned companies and R & D investment intensity. In addition, there is a significant positive relationship between the dual role and R & D investment intensity. The effect of state ownership on R & D investment intensity is more negative when CEO-board chair duality exists. This means that in case of state-owned companies, if CEO serves as the board chair, the propensity to invest in R&D is further reduced. Research implications or Originality - This is a pioneering study that considers the joint effect of state-owned companies and dual role on R & D investment intensity in the Chinese economy.

• Korean Architects
• /
• s.603
• /
• pp.100-101
• /
• 2019

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.4
• /
• pp.226-232
• /
• 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
• /
• v.13 no.2
• /
• pp.13-24
• /
• 1994

The objectives of this study are twofold : (1) to investigate musculoskeletal discomfort for sedentary workers in offices ane (2) to revise the Korean Standard for the design of office chairs in order to reduce or eliminate the physical discomfort or the office workers. Two hundred seventy-one office workers from nineteen different companies companies were selected to evaluate the musculoskeletal discomfort and indibidual features of chair design. A statistical analysis of the survey rebealed that the office currently being used had two major deficiencies such as insufficient adjustability and inappropriate design specifications in ergonomic sense. A stepwise regression analysis showed that the deficiencies on the musculoskeletal discomfort of the workers. Based on the ergonomic design pronciples, was debeloped to revise the Korean Standard for the design specifications of office chairs. An application of the methodology was made amend the design specifications of the four factors such as seat pan height, seat pan width, and seat pan inclunation. Their effects were evident in the musculoskeletal discomfort of the workers.

• Journal of the Korea Furniture Society
• /
• v.12 no.1
• /
• pp.69-79
• /
• 2001

The purpose of this study is to examine the characteristics of Arne Jacobsen's chair design. He was one of the few creators who inscribed his name in both the history of architecture and furniture design. His works reflected a form of "Regional Modernism" in which traditional techniques collide with functionalist beliefs. This grafting of ideas generated a person aesthetics which he used to establish a suitability of scale, detail an program for each design. In the material aspect, he had enjoyed using the plasticity of the plywood, polyurethane, tubular steel and in the formative aspect, organic form is combined with minimalization of material and simplicity. To sum up what is unique about Arne Jacobsen's chair design, it is that it is distinguished by a clear understanding and expression of beauty from nature, a complete understanding of the material used and the melding of traditional and functional techniques to generate organic form.anic form.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.42 no.4
• /
• pp.1-7
• /
• 2019

The customer of massage chair is expanding day by day from middle age to all ages. In 2018, the market size was 700 billion KRW, an increase of 30 times over 10 years. However, most related SMEs suffer from excessive competition by the market monopoly of some major companies. In this situation, in order for a related company to survive, it is necessary to steadily research and develop new products. Founded in 2009, company L produces massage chairs for health and relaxation of customers. L's products use a sound wave vibration module that is favorable for human body, unlike other products that use vibration motor type. However, frequent breakdowns of massage chair due to the vulnerability of plate (leaf) springs, which play an important role in sound wave vibration modules, made sap its competitiveness. In this paper, we propose a method to design desirable plate spring structure by sequentially experimenting with five different plate springs. The results of this study are expected to contribute to improve the quality of plate spring and the reliability of sound wave vibration module. In the future, it is necessary to find a way to use it in the development of foot massage or scalp management device as well as continuous research to find optimal plate spring structure through various analysis.