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RISS 인기검색어
- 검색키워드
- 저자 : Duh, Henry Been-Lirn (검색결과 3 건)
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Duh, Jiunn-Der Geoffrey University of Michigan 2004 해외박사(DDOD)
소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.
There has been considerable recent interest in developing geographic information systems (GIS) applications that incorporate landscape pattern criteria in spatial decision-making. Landscape patterns influence the dynamics of ecosystems, and as such, merit consideration to reconcile other goals and constraints in spatial decision-making. GIS tools capable of analyzing landscape patterns and incorporating pattern information into a spatial decision-support framework for allocating landscape entities have great potential to facilitate achieving pattern goals in land allocation. In this research, I designed, developed, and evaluated a spatial pattern optimization technique called knowledge-informed simulated annealing (KISA) for generating prescribed landscape patterns in single- and multi-objective land-allocation problems and demonstrated the use of such a technique to examine the effect of allocation features on the resulting pattern characteristics. Two KISA rules, the compactness and the contiguity rule, were developed. They encourage the generation of the prescribed landscape patterns at individual locations through uncoordinated discrete steps and reduce the redundancy in the conventional simulated annealing (SA) algorithm. In single-objective problems, the performance of KISA in solving four problems, each using a distinct pattern metric as the optimization objective to achieve the least fragmented landscape, was examined. These metrics are coarse characterizations of shape compactness, connectivity, and interspersion of distinct homogenous areas on a landscape map. In multi-objective problems, I examined the performance of two approaches, (1) knowledge-informed Pareto simulated annealing and (2) Pareto simulated annealing with partially optimized initial solutions, to generating solutions that approximate the multi-objective Pareto front. Four problems were constructed, each with two objectives, representing all combinations of cases in which there are (1) conflicting or concordant objectives and (2) objectives with similar or different degrees of difficulty. The results of multiple-realization experiments were tested for the variation of performance and the effect of spatial constraints. KISA improved the performance of SA in solving spatial optimization problems and illustrated the use of spatial optimization techniques for assessing the effect of design features on landscape patterns. The maps generated by the KISA approaches can be used as tools for initiating discourses on subjective goals among planners, decision makers, and publics.
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Duh, Henry Been-Lirn University of Washington 2001 해외박사(DDOD)
소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.
Simulator sickness (or so-called Cybersickness) has been a significant problem since the development of virtual reality systems. Numerous studies have investigated this problem. However, there is currently no accepted solution. This dissertation addresses development of a possible approach to alleviate simulator sickness. Prior work has suggested the method of inserting an inertially-matched reference visual background grid into a visual scene as an intervention against simulator sickness, but little work has been done to evaluate or optimize such method. This dissertation describes a series of human factors studies to examine and optimize such an “independent visual background” (IVB). Four major components are included. The first part provides a background regarding simulator sickness. The second part examines the dynamics of sensory conflict theory which has been widely accepted as a model of simulator sickness. In this regard we identified and verified a motion frequency where the summed response from the visual and inertial self-motion systems was greatest. We also investigated the effects of field-of-view of the display. The third part explores the possible characteristics of the IVB including spatial, polarity, temporal and stereographic properties of the visual display. As a means of determining subjects' reactions to moving visual stimuli, postural stability, was measured. Postural stability has been proposed as an objective measurement for simulator sickness. The fourth part explores ways that the IVB may reduce subjects' simulator sickness symptoms during the virtual environment exposure. We also consider the relationship between sense of presence and simulator sickness. We conclude that the IVB could be a useful procedure to alleviate simulator sickness and recommend future experiments regarding how the IVB should be presented to enhance users' task performance and cognitive function.
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