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This paper presents a rewritable optical disk with a capacity of 30 GB/side intended for the next generation of rewritable optical disks. The experimental results have shown that this optical disk has wide tilt margin and is a prospective candidate for supplanting VCR in the HDTV era.

For the sake of establishment of a hydrogeological model, the relationships among geological, geophysical and hydraulic properties were discussed, by the use of the data obtained from the rock formation at the Tono area.Performances of hydraulic test equipments recently were also reviewed.Results are summarized as follows:(1) The hydraulic conductivities by PNC Aquifer Test Method (JFT) are quite similar with those by low pressure Lugeon Test Method.(2) Lithology such as grain size and sorting coefficent correlates with hydraulic conductivity.(3) Apparent resistivity, measured by electric logging (100cm normal), correlates closely with hydraulic conductivity.The high correlation between geological and geophygical properties and hydraulic conductivity make possible to estimate hydraulic conductivities by means of Ethology obtained by core logging and electric logging data. The hydrogeological model was successfully constructed by this method.

In order to evaluate the phenomena of masstransportation by groundwater flow in granitic media, it is necessary to make clear geological, hydrogeological and geochemical characteristics of fracture distributed in rock mass.Characteristics of fracture pattern, fracture filling material and alteration in Upper Cretaceous granite are investigated by core logging, mineralogical study, geophysical logging and hydraulic testing. This report describes the results which were obtained in the interval from the ground surface to 500m at Tono area in the central part of Japan.The results are summarized as follows ;(1) Fractures are classified into four groups on the basis of fracture pattern; Planar group (P), Irregular group (I), Curved group (C), and Stepped group (S).(2) Most of fractures belonging to P group and S group have filling materials composed of chlorite, calcite and sericite. Some of the fractures belonging to I group have been filled with materials composed of montmollironite, sericite and chlorite. Fractures of C group hardly have filling material.(3) Some of alterated fracture zones are consisted of P group fractures.(4) As a result of analysis on the fracture pattern and alteration pattern, three segments are recognized; Segment I (from 16.8m to 300m), Segment II (from 300m to 420m), and Segment III (from 420m to 500m). Especially, there are marked differences in fracture pattern and alteration pattern between Segment I and Segment III.