Faculty Profiles - ISHIKAWA, Yoshiharu

Papers - ISHIKAWA, Yoshiharu

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Top-k Query Processing with Replication Strategy in Mobile Ad Hoc Networks Reviewed

Yuya Sasaki, Takahiro Hara, Shojiro Nishio, Yoshiharu Ishikawa

19th IEEE International Conference on Mobile Data Management (MDM 2018) page： 217-226 2018.6

Language：English

In this paper, we propose a method that fully combines top-k query processing with replication strategy in mobile ad hoc networks (MANETs). The goal is to acquire perfect accuracy of query results with a minimal overhead and delay. Currently, no replication strategy achieves efficient allocation of replicas for top-k queries, and no top-k query processing guarantees perfect accuracy of query results in MANETs. We propose a new replication strategy FReT (topology-Free Replication for Top-k query) and new top-k query processing methods. FReT advantages efficient top-k query processing from limited search area even if mobile nodes move. In our top-k query processing method, the search area gradually increases until receiving an exact answer. We demonstrate, through extensive simulations, that our approaches function well in terms of small delay and overhead.

DOI： 10.1109/MDM.2018.00039

ユーザの位置情報を考慮した領域内の影響最大化に対する効率的なアプローチ

勝田健斗, 石川佳治, 杉浦健人

第17回情報科学技術フォーラム（FIT 2018） page： D-003 2018.9

テンソル分解を用いた避難移動軌跡データの分析

河井悠佑, 石川佳治, 杉浦健人

第17回情報科学技術フォーラム（FIT 2018） page： D-004 2018.9

データストリームの集約処理における近似的耐障害性に関する一考察

高尾大樹, 石川佳治, 杉浦健人

第17回情報科学技術フォーラム（FIT 2018） page： D-017 2018.9

気候変動に対応した地域のサステナビリティとレジリエンスを同時に考慮できる評価手法

朴秀日, 加藤博和, 清水大夢, 大野悠貴, 石川佳治, 山中英生, 奥嶋政嗣, 渡辺公次郎, 井若和久, 秋山祐樹

58回土木計画学研究発表会・秋大会論文集 page：（頁番号なし） 2018.11

Loquat: An Interactive System Design for Location-aware Query Autocompletion Reviewed

Sheng Hu, Chuan Xiao, Yoshiharu Ishikawa

9th International Conference on Networking and Information Technology (ICNIT 2018) page： no-page 2018.11

Simulation Data Summarization based on Spatial Histograms Reviewed

Jing Zhao, Yoshiharu Ishikawa, Chuan Xiao, Kento Sugiura

Proceedings of the 21st International Conference on Network and Computing Technology (ICNCT 2019) page： (no page info) 2019.1

Regular Expression Pattern Matching with Sliding Windows over Probabilistic Event Streams Reviewed

Kento Sugiura, Yoshiharu Ishikawa

The 6th IEEE International Conference on Big Data and Smart Computing (IEEE BigComp 2019) 2019.2

Language：English

As smartphones and IoT devices become widespread, event streams, which are continuous analysis results of sensing data, have received a Iot of attention. When we consider the utilization of event streams, it is important to deal with probabilistic event streams due to the noises of sensing data and the limitation of analysis techniques. Although existing methods proposed the monitoring of time series events with regular expressions, there is no efficient method to calculate the occurrence probabilities of time series events with a sliding window. That is, existing methods cannot answer a query such as “does the specified time series event occur in last w time steps?” efficiently. Thus, in this paper, we propose an efficient calculation method by using a deterministic finite automaton (DFA). To calculate occurrence probabilities efficiently, our method divide a window into chunks and reuse the previous calculation results. Besides, we apply lazy evaluation to solve the state explosion problem of a DFA. Experimental results using real and synthetic datasets demonstrate effectiveness and efficiency of our approach.

DOI： 10.1109/BIGCOMP.2019.8679461

Road Segment Interpolation for Incomplete Road Data Reviewed

Yuya Sasaki, Jiahao Yu, Yoshiharu Ishikawa

The 6th IEEE International Conference on Big Data and Smart Computing (IEEE BigComp 2019) page： 10.1109/BIGCOMP.2019.8679461 2019.2

Language：English

Road data is fundamental information for location-based services. We trust that the road data is complete to represent an actual road network when we develop the location-based services. However, road data may be incomplete due to update delays, and thus location-based services may not provide useful results. Several algorithms have been proposed to automatically update road data. In this paper, we study interpolation of missing road segments by using vehicle trajectory data. We can find missing road segments from the trajectories because vehicles may pass through road segments that are not included in road data. However, trajectories are inherently noisy due to GPS errors. Hence, we cannot easily interpolate appropriate road segments. We propose an algorithm based on map matching and clustering techniques for achieving accurate and comprehensive interpolation. Our algorithm first detects trajectories that are probably on missing road segments. It then clusters the trajectories by DBSCAN and integrates the trajectories for interpolating the road data. Through the experiments using real incomplete road data and trajectory data, we verify that our algorithm effectively interpolates the missing road segments.

Estimating People Flow from a Large Amount of Aggregated Data with a Few Tracking Data Reviewed

Yusuke Kawai, Yusuke Tanaka, Hiroyuki Toda, Yoshiharu Ishikawa

DBSJ Japanese Journal Vol. 17 page： Article No. 7 2019.3

ソーシャルネットワークにおける特定のユーザを対象とした影響最大化

勝田健斗, 石川佳治, 杉浦健人

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D2-2 2019.3

識別モデルを用いたスコープを意識したコード補完 Reviewed

胡晟, 肖川, 石川佳治

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： G4-1 2019.3

確率モデルに基づく近似的な耐障害性の保証

高尾大樹, 石川佳治, 杉浦健人

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D4-3 2019.3

データストリーム管理システムに関する再考

杉浦健人, 石川佳治

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D4-4 2019.3

テンソル分解を用いた避難移動軌跡データの分析

河井悠佑, 石川佳治, 杉浦健人

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： A6-2 2019.3

道路ネットワークのスパース性に着目した車両軌跡の圧縮索引

小出智士, 肖川, 石川佳治

第11回データ工学と情報マネジメントに関するフォーラム (DEIM 2019) page： D7-4 2019.3

データベース管理システムにおける3D TIN 管理の検討

杉浦健人, 椎名健, 石川佳治

第81回情報処理学会全国大会 page： 2C-3 2019.3

大規模点群データ分析のためのデータベースの検討

笠井雄太, 石川佳治, 杉浦健人

第81回情報処理学会全国大会 page： 2Q-5 2019.3

Indexing Trajectories for Travel-Time Histogram Retrieval Reviewed

Robert Waury, Christian S. Jensen, Satoshi Koide, Yoshiharu Ishikawa, Chuan Xiao

22nd International Conference on Extending Database Technology (EDBT 2019) page： 157-168 2019.3

Analysis of Evacuation Trajectory Data Using Tensor Decomposition Reviewed

Yusuke Kawai, Yoshiharu Ishikawa, Kento Sugiura

Journal of Disaster Research Vol. 14 ( 3 ) page： 521-530 2019.3

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Papers - ISHIKAWA, Yoshiharu