Browsing by Author "Kim, Hyung Nam"

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    The Effects of Transitioning Between Different Floor Surfaces on Gait Characteristics of the Elderly
    Kim, Hyung Nam (Virginia Tech, 2005-09-16)
    Each year the rate of slip and fall accidents increases among older individuals. Most falls among the elderly occur indoors rather than outdoors, and of the falls that occur in the residential home, over 600,000 are due to floor covering materials. In particular, carpet and vinyl are common floor coverings used in the home today as the elderly often transition from carpet to vinyl and vice versa. When transitioning between two different floor surfaces, older adults may adjust their gait to avoid a slip, trip, or fall. Many studies have assessed gait parameters of elderly individuals on either carpet or vinyl. Yet, few have studied the effect of transitioning between two different floor surfaces on the gait of older individuals. This study investigated the effect of transitioning between different floor coverings on the gait characteristics of the elderly. For this study, 14 elderly (65 years old and over) and 14 young (18 to 35 years old) individuals participated. All participants walked on different transitional floors, namely carpeted floors, vinyl floors, and floors covered with both vinyl and carpet. While the participants were walking on the walkway, different gait parameters were measured, including the required coefficient of friction, stride length, transitional acceleration of the whole body center-of-mass (COM), heel velocity at heel contact, perception of slipping/tripping, and toe clearance. It was hypothesized that older participant's gait parameters would be different from their younger counterparts. Also, the older participant's gait adaptation would increase the likelihood of a slip and trip propensity while transitioning between different floor surfaces compared to the younger participants. More specifically, for the elderly, transitioning from carpeted floor surfaces to vinyl floor surfaces would increase the slip propensity and transitioning from vinyl floor surfaces to carpeted floor surfaces would increase trip propensity, and therefore increase the likelihood of fall accidents. In the present study, it was found that elderly individuals had greater toe clearance than their younger counterparts. Also, the elderly individuals had smaller toe clearance on the carpet than on the vinyl, which would increase the probability of a trip-induced fall when walking on the carpet. Further, the propensity of a slip-induced fall accident increased on the vinyl shortly after transitioning from the carpet to the vinyl due to the slower transitional acceleration of the whole body COM and the increased friction demand, especially during the toe-off phase of the gait cycle, rather than heel contact phase of the gait cycle. In addition, it was also found that an increase in heel contact velocity and step length increases the propensity of a slip-induced fall accident. Furthermore, this propensity is greater while transitioning from a carpet to a vinyl floor surface, especially for elderly individuals. The results of the present study indicate that transitioning between different floor surfaces changes the biomechanical parameters of gait, especially for the elderly individuals. Although the increased likelihood of a slip or trip accident was found throughout the changes in biomechanical gait parameters, the elderly individuals who participated in this study did not perceive of slipping and tripping much. Therefore, elderly individuals should be made aware of
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    Usable Accessibility and Haptic User Interface Design Approach
    Kim, Hyung Nam (Virginia Tech, 2010-04-02)
    Many people have visual impairment and make up a population that is increasing each year. Haptic technology is often used to assist members of this population by providing a way of understanding visual information. Although haptic technology is relatively new, it is widely applied across a variety of domains (research and industry). However, a great number of users are dissatisfied with their assistive technology applications. Unfortunately, such dissatisfaction is likely to cause abandonment of the technology devices. In particular, recent research shows that the adoption rate of haptic technology is low. Discontinuing the use of assistive technology devices ultimately results in a waste of time, money, freedom, and reduced function for individuals with disabilities. Of all the factors that lead to abandonment, the most significant is the failure to meet user needs. Whether existing design approaches properly reflect assistive technology user needs should be explored, especially for haptic technology. Existing design approaches have rarely considered the heterogeneous needs of users in the same disability category (i.e., visual disability). Most previous studies on assistive technology have been oriented towards those with total blindness as opposed to those with residual vision (also referred to as low vision). In addition, researchers have paid less attention to older adults with low vision in terms of individual differences in haptic user interface (HUI) needs. There is also some doubt about the applicability of existing design approaches in such design contexts as users with visual disabilities using haptic user interfaces. The aim of this research was to investigate individual differences in users' capabilities in the haptic modality and user needs in HUIs. Particularly, age-related and vision-related individual differences were explored. Another aim was to develop a more accessible design approach applicable to users with visual disabilities and HUIs. The magnitude estimation technique was employed to examine how participants (classified by vision and age) perceive the same objective stimulus, such as haptic perception, differently. Brain plasticity theory was primarily applied to modify the existing design approach, PICTIVE. The effectiveness of modified and original PICTIVE methods was investigated in terms of the frequency of statements, gestures, satisfaction, and time to complete a given design task. HUI user needs were elicited from participants and were analyzed to understand age-related and vision-related individual differences. It was found that the haptic perception of the same objective stimulus was not significantly different between younger and older participants with low vision. The two age groups' overall preferences for a set of HUI user needs were not significantly different. In addition, the haptic perception of the same objective stimulus was not significantly different between sighted participants and those with low vision. The two vision groups' overall preferences on a set of HUI user needs were not significantly different as well. The two design methods resulted in significantly different outcomes. First, participants in the modified PICTIVE method made a significantly higher number of statements. Second, participants in the modified PICTIVE method showed a significantly higher number of gestures. Third, participants in the modified PICTIVE method took significantly more time because they had more design ideas to deliver. Last, both groups were satisfied with a given design method. In short, the research outcomes contribute to the advancement of knowledge and understanding of more "usable" accessibility for users with visual impairment and a more "accessible" participatory design approach to nontraditional user interfaces (i.e., haptic user interfaces) for users with visual impairment.