Ipsj Digital Courier最新文献

{"title":"Exploratory Session Analysis in the Mobile Clickstream","authors":"T. Yamakami","doi":"10.2197/IPSJDC.3.14","DOIUrl":"https://doi.org/10.2197/IPSJDC.3.14","url":null,"abstract":"As a sub-day-scale behavior analysis, the length of sessions in multiple mobile Internet services was examined. Using mobile clickstreams with user identifiers, two analyses were performed: a preparatory study for timeout values in session identification in 2000 and a long-term observation of session lengths and clicks per session in 2001. The first study showed that 10 minutes is a suitable timeout value for the observed mobile web. The second produced inter-service comparisons and showed the effects of different mobile-Internet-specific factors. The limitations and challenges for mobile-clickstream-based session identification are also discussed.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132448832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Finding an Edit Script between an XML Document and a DTD","authors":"Nobutaka Suzuki","doi":"10.2197/IPSJDC.2.813","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.813","url":null,"abstract":"","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115001671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Model Checking Active Database Rules under Various Rule Processing Strategies","authors":"Eun-Hye Choi, Tatsuhiro Tsuchiya, T. Kikuno","doi":"10.2197/IPSJDC.2.826","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.826","url":null,"abstract":"An active database is a database system that can react to internal, as well as external, database events. The reactive behavior of an active database is determined by a predefined set of active database rules, along with a rule processing strategy. A common problem associated with active database systems is the possible non-termination of the active database rules. Previous work on the analysis of the conditions required for the termination of active database rules has only considered limited rule processing strategies. This paper proposes an approach for automatically detecting the non-termination of active database rules using a model checking technique. With this approach, a general framework for modeling active database systems is first proposed. This framework is useful for analyzing the behavior of rules with different rule processing strategies and for allowing the adoption of different contexts and different execution coupling modes for the active database rules. Based on the proposed modeling framework, the termination property of active database rules with various rule processing strategies is next checked using SPIN, a model checking tool. Through experimental results, we demonstrated the feasibility of using this method.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115180387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Zigzag-HVP: A Cost-effective Technique to Mitigate Soft Errors in Caches with Word-based Access","authors":"L. D. Hung, M. Goshima, S. Sakai","doi":"10.2197/IPSJDC.2.748","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.748","url":null,"abstract":"Error Correction Code (ECC) is widely used to detect and correct soft errors in VLSI caches. Maintaining ECC on a per-word basis, which is preferable in caches with word-based access, is expensive. This paper proposes Zigzag-HVP, a cost-effective technique to detect and correct soft errors in such caches. Zigzag-HVP utilizes horizontal-vertical parity (HVP). HVP maintains the parity of a data array both horizontally and vertically. Basic HVP can detect and correct a single bit error (SBE), but not a multi-bit error (MBE). By dividing the data array into multiple HVP domains and interleaving bits of different domains, a spatial MBE can be converted to multiple SBEs, each of which can be detected and corrected by the corresponding parity domain. Vertical parity updates and error recovery in Zigzag-HVP can be efficiently executed through modifications to the cache data paths, write-buffer, and Built-In Self Test. The evaluation results indicate that the area and power overheads of Zigzag-HVP caches are lower than those of ECC-based ones.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122391908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mining Sequential Patterns More Efficiently by Reducing the Cost of Scanning Sequence Databases","authors":"Jiahong Wang, Yoshiaki Asanuma, Eiichiro Kodama, T. Takata, Jie Li","doi":"10.2197/IPSJDC.2.768","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.768","url":null,"abstract":"Sequential pattern mining is a useful technique used to discover frequent subsequences as patterns in a sequence database. Depending on the application, sequence databases vary by number of sequences, number of individual items, average length of sequences, and average length of potential patterns. In addition, to discover the necessary patterns in a sequence database, the support threshold may be set to different values. Thus, for a sequential pattern-mining algorithm, responsiveness should be achieved for all of these factors. For that purpose, we propose a candidate-driven pattern-growth sequential pattern-mining algorithm called FSPM (Fast Sequential Pattern Mining). A useful property of FSPM is that the sequential patterns concerning a user-specified item can be mined directly. Extensive experimental results show that, in most cases FSPM outperforms existing algorithms. An analytical performance study shows that it is the inherent potentiality of FSPM that makes it more effective.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"8 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128293448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Study on the Self-Similarity of TCP Reno and TCP Vegas","authors":"P. Rácz, T. Matsuda, M. Yamamoto","doi":"10.2197/IPSJDC.2.783","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.783","url":null,"abstract":"Self-similar traffic patterns have been observed in many measurements of Internet traffic. Self-similarity is very detrimental to the performance of packet networks and recent research has focused on understanding and reducing its amount in Internet traffic. TCP Reno has been identified as being one of the primary sources of self-similarity. We explore the potential of another version of TCP in this paper to reduce the degree of self-similarity in aggregated TCP traffic. We decompose both TCP Reno and TCP Vegas to demonstrate and explain their underlying mechanisms, and separately measure what effects congestion-avoidance and timeouts/exponential backoff mechanisms have on the self-similarity in aggregated TCP flows. We reveal how TCP Vegas reduces the degree of self-similarity and eventually completely eliminates it from aggregated TCP flows at low levels of packet loss. However, at high levels of packet loss we show that TCP Vegas is detrimental, because it increases the degree of aggregated TCP-flow self-similarity.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132968000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Hybrid Data Delivery Method of Data Broadcasting and On-demand Wireless Communication","authors":"Jing Cai, T. Terada, T. Hara, S. Nishio","doi":"10.2197/IPSJDC.2.840","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.840","url":null,"abstract":"As the recent advances in the wireless technologies and mobile terminals, mobile users equipped with mobile devices are able to access wireless services through 3G cellular network, WiFi hotspot, or WiMAX link, as well as through satellite digital broadcast or terrestrial digital broadcast. By effectively taking advantage of these complementary communication modes, we explore a new hybrid data delivery model, i.e., Hybrid Wireless Broadcast (HWB) model to benefit from the optimal combination of the push-based and pull-based broadcast and on-demand point-to-point wireless communication. The HWB model can provide a flexible and complementary information service in different bandwidths and service ranges, and greatly improve the responsibility, scalability, and efficiency of the system. The results of simulation study show the proposed HWB approach achieves a significant improvement in system performance.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131011503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving Path Discovery Performance in Dense Mobile Ad Hoc Networks","authors":"Yujin Noishiki, H. Yokota, A. Idoue","doi":"10.2197/IPSJDC.2.804","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.804","url":null,"abstract":"In on-demand ad-hoc routing protocols, control packets are flooded into a network during path discovery. Especially in dense ad-hoc networks, these protocols generate a large number of broadcast packets that cause contention, packet collisions and battery power wastage in mobile nodes. We propose an efficient route establishment method that adaptively lowers re-broadcasting overhead based on the number of adjacent nodes and the number of routes that these nodes accommodate. Through simulation, we demonstrate that our proposed method is especially efficient in densely populated areas. It achieves efficiency by lowering the number of control packets for path discovery without causing a drop in the path discovery success ratio. Also, by taking path concentration into account, our method further improves packet delivery. We provide useful guidelines based on simulation results.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131342682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Index Allocation Method for Data Access over Multiple Wireless Broadcast Channels","authors":"Damdinsuren Amarmend, M. Aritsugi, Yoshinari Kanamori","doi":"10.2197/IPSJDC.2.852","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.852","url":null,"abstract":"With the advent of mobile technology, broadcasting data over one or more wireless channels has been considered an excellent way to efficiently disseminate data to a large number of mobile users. In such a wireless broadcast environment, the minimization of both access and tuning times is an important problem because mobile devices usually have limited battery power. In this paper, we propose an index allocation method for data access over multiple channels. Our method first derives external index information from the scheduled data, and then allocates it over the channels, which have shorter broadcast cycles and hotter data items. Moreover, local exponential indexes with different parameters are built within each channel for local data search. Experiments are performed to compare the effectiveness of our approach with an existing approach. The results show that our method outperforms the existing method by 30% in average access time and by 16% in average tuning time when the data skew is high and data item size is much bigger than index node size.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133813428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of τ-Gradual Key-Management Schemes for Mobile Content Distribution","authors":"Kazuhide Fukushima, S. Kiyomoto, Toshiaki Tanaka","doi":"10.2197/IPSJDC.2.792","DOIUrl":"https://doi.org/10.2197/IPSJDC.2.792","url":null,"abstract":"Copyright protection is a major issue in online content-distribution services and many key-management schemes have been proposed for protecting content. Key-distribution processes impose large burdens even though the communications bandwidth itself is restricted in the distribution of mobile content provided to millions of users. Mobile devices also have low computational capacities. Thus, a new scheme of key management, where the load on the key-distribution server is optimal and loads on clients are practical, is required for services. Tree-based schemes aim at reducing the load on the server and do not take reducing the load on clients into account. The load on clients is minimized in a star-based scheme, on the other hand, while the load on the server increases in proportion to the number of clients. These structures are far from being scalable. We first discuss a relaxation of conventional security requirements for key-management schemes in this paper and define new requirements to improve the efficiency of the schemes. We next propose the τ-gradual key-management scheme. Our scheme satisfies the new security requirements and loads on the server, and it has far fewer clients than conventional schemes. It uses an intermediate configuration between that of a star- and a tree-structure that allows us to continuously change it by controlling the number of clients in a group, mmax. The scheme can be classified as τ-star-based, τ-tree-based, or τ-intermediate depending on the parameter, mmax. We then present a quantitative evaluation of the load on the server and clients using all our schemes based on practical assumptions. The load on the server and that on clients involves a trade-off with the τ-intermediate scheme. We can construct an optimal key-management structure according to system requirements using our schemes, while maintaining security. We describe a concrete strategy for setting parameter mmax. Finally, we present general parameter settings by which loads on both the server and clients using the τ-intermediate scheme are lower than those using the τ-tree-based scheme.","PeriodicalId":432390,"journal":{"name":"Ipsj Digital Courier","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127843368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}