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Birch chips, treated with bisulfite at various yield (70-90%), were fiberized in the Asplund Laboratory Defibrator D (as the first refining) and refined in the PFI mill (as the second refining) to produce CTMP.The effects of pretreatment yields and refining temperatures on the fiber length distributions and fiber surface structures of CTMP were discussed. In addition, the relationships between morphlogical properties of the fines and the sheet strength properties were discussed.At the yield of pretreated chips less than 84%, the fiber wall of the pretreated chips were ruptured between the primary wall and the middle lamella on the fiberizing stage, and then the fibers were seperated without damaging. The fines generated on this stage consisted of the ray cell and the flake-like fragments which were derived from the middle lamella and the primary wall layer.At the yield of pretreated chips more than 90%, the pretreated chips were fiberized in a similar manner descrived above. However, the presence of fragments derived from the cell wall was found in the fines fraction.In the case of various yields, there is no significant differences in the long fiber (> 48 mesh) contents of the pulps produced on the fiberizing stage.When the defibration temperture decreased from 130°C to 100°C or 20°C, the fibers were significantly damaged during the fiber seperation, and the contents of the long fiber decreased.Fiber surface structures and the fiber length distributions showed that the fibers produced from the pretreated chips with a yield of 93% were subjected to destruction on the refining stage, and decreased the long fiber contents. The fines generated on this stage contained more fiber wall fragments.This tendency was reduced with decrease of the pretreatment yield, and a larger portion of the fines consisted of the fillament-like fragments which were derived from the secondary wall by peeling from the fiber surface.The fines generated on the fiberizing stage were less effective to the sheet strength properties. On the other hand, the fines generated on the refining stage consisted of the fillament-like fragments which derived from the secondary wall, and were more effective to the inter fiber bonding.

A study has been carried out to determine the influence of chemical pretreatments on the physical properties of chemithermomechanical pulps (CTMP) made from hardwood chips which were chemically treated with sulfite liquors at the range from pH 1.8 to 13.0.Of the chemical pretreatments investigated, neutral sulfite (pH 9.8) and bisulfite (pH 4.1) appeared to offer the greatest potential for strength development to produce CTMP from hardwood chips. Alkaline sulfite (pH 13.0) and acid sulfite (1.8) treatment, on the other hand, have little effect on the strength properties of CTMP.As far as energy requierment is concerned, pretreatment with sulfite liquor at low pH (4.11.8) leads to a substantial reduction in refining energy. However, there are distinct differences in the long fiber contents between acid sulfite CTMP and bisulfite CTMP. In the case of acid sulfite-and bisulfite-pretreatments, The strength properties of CTMP from birch wood were higher than those of CTMP from oak wood.The ultraviolet microscope was used to follow the delignification visually during acid sulfite-and bisulfite-pretreatment of birch wood. When the birch wood was delignified with bisulfite, the topochemical effect was not detected, while topochemical preference for the removal of lignin from the secondary wall was found in the case of acid sulfite-pretreatment.Furthermore, it was found that total pore volume and median pore width of cell wall treated with bisulfite was larger than that of cell wall treated with acid sulfite.

Double random phase encoding (DRPE) is a classical optical symmetric-key encryption method. DRPE prevents the key length from being determined because of its redundancy between encryption and decryption, unlike digital symmetric-key cryptographies. In our study, we numerically analyzed the key length of DRPE based on key-space analysis. We estimated the key length of DRPE by calculating the inverse value of the cumulative probability of the normal distribution that was estimated from samples of DRPE and then discuss security against brute-force attacks.

In order to reduce the risk of theft or leakage of personal information captured by biometric sensing, we have proposed novel biometric sensing techniques in which biometric image can be captured using optical encryption methods. These methods, called encrypted sensing, are based on double random phase encoding (DRPE) and compressed sensing (CS). Encrypted sensing based on DEPR is implemented through digital holography (DH). On the other hand, encrypted sensing system based on CS is composed of digital micromirror device for random intensity modulation and single pixel camera. Through experiments using fingerprint images and finger vein images, we confirm that biometric images can be obtained as they are encrypted, and they can be restored correctly from the encrypted images.