Isao Sawaguchi

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 Experimental results were studied to determine the relationships between positioning precision of a differential global positioning system (DGPS) and forest type, antenna height, and season, and to clarify the relationship between sampling number and the convergence of positioning precision. Observation was carried out for 24 h. Mean circular area(More)
This study investigated the relationship between the quantity of the shielding effect by wood material and the lowering of the signal to noise ratio (SNR) of global positioning system (GPS), signals. Three types of wood materials, namely, Japanese cedar board (JCB), Japanese cedar needle (JCN), and deciduous broadleaf (DBL), were prepared. We performed(More)
This study examines a method for designing an optimum profile of a forest road in a short matter of time. In this method, a genetic algorithm (GA) searches for points where the gradient changes and dynamic programing (DP) designs the longitudinal slope. This method can be applied to the ground heights of an actual forest road. The evaluation function of the(More)
This study was performed to investigate the factors responsible for the reduction in the signal-to-noise ratio (SNR) of a global positioning system (GPS) when used in a forest. We investigated the relationship between the SNR values of GPS signals and the moisture in wood materials and clarified this relationship through experimentation and simulation.(More)
The growing condition of afforestation trees and damage to lower-story trees caused by felling and hauling of upper-story trees in a multi-storied forest in Peninsular Malaysia was surveyed. Seventy months have passed since the planting ofAcacia mangium upperstory trees, which have grown 233 m3/ha in volume. The growth ofShorea leprosula thirty-five months(More)
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