This paper describes a novel shared file system, whose main features are enhanced security and its concurrency control mechanism. The system is especially suitable for access from mobile hosts. Users can edit their shared files concurrently. Shared files are encrypted and decrypted only by clients, and the file server cannot know the contents. The server asynchronously receives the edited parts, which are already encrypted, and merges them into the current version, deciphering neither the stored file nor the encrypted editing data. We call the mechanism 'privacy enhanced merging'. The mechanism and the underlying encryption algorithm, shared file data structure and procedures followed by clients and the server are shown.

This paper provides conceptual and experimental analysis of a new approach in the study of kanji, our “Learner's Visualization (LV) Approach”. In a previous study we found that the LV Approach assists beginning learners in significantly updating their personal kanji deconstruction visualization. Additionally, in another study our findings provided evidence that beginning learners also receive a significant impact in the ability to acquire vocabulary. In this study, our research problem examines how beginning and intermediate students use visualization to cognitively deconstruct (divide) kanji in different ways, and how this affects their learning progress. We analyze the cognitive differences in how kanji learners explore and deconstruct novel kanji while using the LV Approach and how these differences affect their learning process while using the LV Approach. During the learning experience, our LILES System (Learner's Introspective Latent Envisionment System), based on the LV Approach, guides learners to choose from a set of possible “kanji deconstruction layouts” (layouts showing different ways in which a given kanji can be divided). The system then assists learners in updating their “kanji deconstruction level” (the average number of parts they visualize within kanji according to their current abilities). Statistical analysis based on achieved performance was conducted. The analysis of our results proves that there are cognitive differences: beginners deconstruct kanji into more parts (“blocks”) than intermediate learners do, and while both improve their kanji deconstruction scores, there is a more significant change in “kanji deconstruction level” in beginners. However, it was also found that intermediate learners benefit more in “kanji retention score” compared with beginners. Suggestions for further research are provided.

A low-loss polarization-selective grating with a symmetrical double structure is proposed for wider frequency band use. Theoretical transmission loss is smaller than 0.025 dB in the frequency band of 0.6551.185 which is twice as wide as the previously reported one.

Simple and closed form expressions for reflection and transmission coefficients of a thin strip grating on a dielectric sheet are presented for the use of antenna application. In the analysis, a set of integral equations for the aperture fields between strips are derived from the three dimensional boundary value problem. Upon use of the low frequency approximation, closed form expressions are obtained for reflection and transmission coefficients. The accuracy of our approximation results is examined numerically by making use of the Point Matching Method. It is shown that the accuracy is excellent provided 1) the period of gratings is smaller than about 0.3 free space wavelength, and 2) the thickness of the dielectric sheet is greater than about 0.3 times the grating period.