Cheol Woong Ko

Biomechanical effect of changes in bed positions and different types of mattresses in preventing decubitus ulcer

The optimal bed position of the patient in the bed to prevent decubitus ulcers and the best effective mattress in preventing these ulcers is also controversial. The objective of this study was to analyze the effects of changes in bed position on different types of mattresses during frequent nursing activities on the contact pressure between the patient’s body and the mattress. The fifteen normal healthy subjects were selected and divided into three groups (normal, overweight, and underweight) with respect to body mass indexes. We set up five positions of three-stage segmental motorized beds and used four types of ulcer-preventing mattresses (latex, bubble, alternative and air) and ordinary hospital mattress. The contact pressure at three areas of the shoulder-scapular, pelvis-sacrum and heel-ankle using pressure measurement system were measured. The results showed that the head-foot at 30 degrees was the best position to mitigate the possibility of a decubitus ulcer with regard to the subject’s position in the bed. Regarding the type of mattress, the air mattress was the most effective in ameliorating a decubitus ulcer. In addition, those who were underweight were more vulnerable to a decubitus ulcer than those who were overweight. Therefore both optimal bed position and appropriate ulcer-preventing mattress for body mass indexes should be considered to alleviate the development of decubitus ulcer for nursing activities of critically ill patients.

Design and control of actively combined carrier system for the elderly

In this work, an active conbined carrier which combines a wheel chair and a bed is introduced. This carrier is designed for disabled or elderly persons by providing them with an integrated moving carrier and bath-bed, helping them use a bath without using their bodies. In particular, omni-directional wheels are utilized to move to any direction without turning the carrier body widely, reducing turing space and operation time. To be combined with the lying bathtub, the bed and wheel chair are separated by using distinguished mechanisms. At the same time, the carrier is designed to be docked with the bathtube autonomosly or manually. An appropriate wheel base is determined by taking weight balance and pulling force in a incline into consideration, which contributes to preventing turn-over in any case.

A motorized and easy-docking wheelchair drive for persons with lower-limb disabilities

The aim of this study is to develop a driving module that can be attached to a manual wheelchair with an easy-docking mechanism to assist persons with lower-limb disabilities. The driving module consists of a motorized driving mechanism, embedded control boards, and an easy-docking mechanism, which can together be used to convert a manual wheelchair to an electrical wheelchair. The core of the easy-docking mechanism comprises the snatch locks and yokes, with which the driving module can be attached in front of a manual wheelchair and firmly fixed on the wheelchair frame. After the attachment, the wheelchair can be operated like a motorcycle. A brusless DC (BLDC) motor and a wheel dragged the wheelchair, and it was controlled by micro-controllers (MCUs). The MCU determined the motor input based on the throttles, a hall sensor, a brake, a battery, and limit switches. The current driving status was displayed via an LCD panel that was activated by a cluster board. The driving module was tested to evaluate the performances and the results showed that the developed system was helpful in increasing the mobility of persons with lower-limb disabilities.

Structural Stability Analysis of Connectors for an Electric Handbike

Electric handbike can be easily detachable to various sizes of manual wheelchair and the elderly and people with disabilities can use them easily. Therefore, connectors used for coupling between the handbike and manual wheelchair must secure structural stability for occupant safety. However, related research is rare. The aim of this study is to find the connector with highly structural stability by comparing static and dynamic mechanical characteristics among three typical connectors(a snatch lock, a slide latch, and a fastener) by computational simulations. To perform static and dynamic simulation, we referred to durability test based on Korean Standards and then calculated mechanical stresses in connectors. The results showed that the snatch lock addressed the lowest von-mises stress under the same mechanical condition. Therefore when using the combination of a handbike and a wheelchair, we concluded that the snatch lock is considered as the structurally stable connector to structural stability and usability.Electric handbike can be easily detachable to various sizes of manual wheelchair and the elderly and people with disabilities can use them easily. Therefore, connectors used for coupling between the handbike and manual wheelchair must secure structural stability for occupant safety. However, related research is rare. The aim of this study is to find the connector with highly structural stability by comparing static and dynamic mechanical characteristics among three typical connectors(a snatch lock, a slide latch, and a fastener) by computational simulations. To perform static and dynamic simulation, we referred to durability test based on Korean Standards and then calculated mechanical stresses in connectors. The results showed that the snatch lock addressed the lowest von-mises stress under the same mechanical condition. Therefore when using the combination of a handbike and a wheelchair, we concluded that the snatch lock is considered as the structurally stable connector to structural stability and usability.