Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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Combinational Effect of Spot-checking in Sabotage-tolerance for Volunteer Computing

WATANABE Kan, FUNABIKI Nobuo, NAKANISHI Toru, FUKUSHI Masaru

111 ( 408 ) 103 - 108 2012.1

An Improved Java Programming Learning System Using Test-Driven Development Method

Nobuo Funabiki, Yuuki Pukuyama, Yukiko Matsushima, Toru Nakanishi, Kan Watanabe

INTERNATIONAL MULTICONFERENCE OF ENGINEERS AND COMPUTER SCIENTISTS, IMECS 2012, VOL I 597 - 602 2012

Authorship：Lead author Language：English Publisher：INT ASSOC ENGINEERS-IAENG

To enhance educational effects of Java programming by assisting self-studies of students and reducing teaching loads of teachers, we have proposed a Web-based Java programming learning system using the test-driven development method. In this system, a teacher should register Java programming assignments with statements, model source codes, and test codes using a Web browser. Then, a student can submit a test code and an answer source code for each assignment, where both codes are tested automatically by a testing tool called Junit at the server. Unfortunately, the current system cannot identify an incomplete test code that does not contain the complete test procedures if it has no grammatical error. In this paper, we introduce a code coverage measurement tool called Cobertura to detect such a test code by measuring the coverage rate when the submitted test code tests the model source code. We evaluate the effectiveness of our improved system through experiments with two simple assignments to 11 students who have studied Java.

A dynamic rescheduling extension of cooking-step scheduling algorithm for multiple dish cooking

Yukiko Matsushima, Nobuo Funabiki, Toru Nakanishi, Kan Watanabe

The 2nd International Conference on Applied and Theoretical Information Systems Research (2nd ATISR2012) 2012

A code design learning function in Java programming learning assistant system using test-driven development method

Nobuo Funabiki, Takuya Nakamura, Yukiko Matsushima, Toru Nakanishi, Kan Watanabe

The 2nd International Conference on Applied and Theoretical Information Systems Research (2nd ATISR2012) 2012

An application of cooking-step scheduling algorithm for homemade cooking and its extensions

Yukiko Matsushima, Nobuo Funabiki, Toru Nakanishi, Kan Watanabe

1st IEEE Global Conference on Consumer Electronics 2012, GCCE 2012 94 - 98 2012

Language：English

Homemade cooking can have a key role for a healthy and cost-efficient life. To help this activity for busy people such as workers, students, and child-rearing families, we have proposed a cooking-step scheduling algorithm to suggest an optimal sequence of the cooking-steps when multiple dishes are cooked within a limited time. In this algorithm, the cooking procedure for each dish is divided into a set of cooking-steps, and the execution sequence of all the cooking-steps for the dishes is optimized such that the total cooking time is minimized. In this paper, we first show our application result of this algorithm in cooking five dishes and the arisen problems through this experiment. Then, we present four extensions of this algorithm to solve them. Through simulations and cooking experiments, we verify the effectiveness of the algorithm extensions. © 2012 IEEE.

DOI： 10.1109/GCCE.2012.6379977

An extension of routing tree algorithm for smart antenna use in wireless Internet-access mesh network

Nobuo Funabiki, Toru Nakanishi, Kan Watanabe

1st IEEE Global Conference on Consumer Electronics 2012, GCCE 2012 633 - 637 2012

Authorship：Lead author Language：English

As a cost-efficient scalable Internet-access network, we have studied the architecture, protocols, and design optimizations of the Wireless Internet-access Mesh NETwork (WIMNET). WIMNET is composed of wirelessly connected multiple access-points (APs), where at least one AP acts as a Gateway (GW) to the Internet. Two types of APs are used for the hierarchical configuration to achieve scalability with sufficient bandwidth and low costs, namely, a programmable Smart AP (SAP) equipped with multiple antennas, and a non-programmable Conventional AP (CAP) with a single antenna. For a SAP, a smart antenna using an array antenna should be adopted to enhance the performance by allowing simultaneous activations of multiple links. Because the transmission capacity of a SAP with m antennas can be ideally m times of that of a CAP, the routing path should consider this difference so that the average delay between the GW and any AP be minimized to avoid bottlenecks. In this paper, we present an extension of our previous routing tree algorithm for this smart antenna use in WIMNET to improve the throughput by considering the feature. We evaluate the throughput improvement through simulations using the WIMNET simulator. © 2012 IEEE.

DOI： 10.1109/GCCE.2012.6379938

Implementation and Evaluation of an Pairing-Based Anonymous Credential System with Constant-Size Proofs and Efficient Proof Generations

Nasima Begum, Toru Nakanishi, Nobuo Funabiki

2012 THIRD INTERNATIONAL CONFERENCE ON NETWORKING AND COMPUTING (ICNC 2012) 264 - 268 2012

Language：English Publisher：IEEE

To enhance user privacy, anonymous credential systems allow the user to convince a verifier of the possession of a certificate issued by the issuing authority anonymously. In the systems, the user can prove logical relations on his/her attributes embedded into the certificate. Previously, we proposed a pairing-based system with constant-size proofs. In the system, the proof generation needs only multiplications depending on the size of the proved relations, and it is more efficient than other existing system that needs the exponentiations whose costs are much larger than multiplications. However, our efficient system has never been implemented, and thus the practicality is not evaluated. In this study, we implemented the system, and measured the processing times and data size, when changing the parameters describing the size of the proved relation. The verification time is very fast and constant, and the proof size is also constant, from which we can confirm the practicality. However, the proof generation time increases, when the parameters increase. Although we confirm the practicality in case of small relations, we clarify the problems in case of larger relations, which should be solved in our future works.

DOI： 10.1109/ICNC.2012.48

Efficient proofs for CNF formulas on attributes in pairing-based anonymous credential system

Nasima Begum, Toru Nakanishi, Nobuo Funabiki

15th Annual International Conference on Information Security and Cryptology (ICISC 2012) 2012

An Error Code Highlighting Function in Java Programming Learning Assistant System Using Test-Driven Development Method

Nobuo Funabiki, Yuuki Fukuyama, Yukiko Matsushima, Toru Nakanishi, Kan Watanabe

WORLD CONGRESS ON ENGINEERING AND COMPUTER SCIENCE, WCECS 2012, VOL I 230 - 235 2012

Authorship：Lead author Language：English Publisher：INT ASSOC ENGINEERS-IAENG

Recently, the objected-oriented programming language Java has been used in many practical systems including enterprise servers, smart phones, and embedded systems due to its high reliability and portability. To enhance effects of Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS adopts the Test-Driven Development (TDD) method for automatic testing of source codes written by students on the server to assist their self-learning. In JPLAS, a teacher needs to register each Java programming assignment with a statement, a reference source code, and a test code. Then, students should write source codes by referring this statement and the test code so that their source codes can be tested automatically at the server by a testing software tool called JUnit with the test code. Unfortunately, the current JPLAS is not friendly to students who have difficulty in reading the log message from JUnit that contains the information on the errors in the source code. In this paper, we implement the error code highlighting function to help such students to find erroneous lines in the code by highlighting them graphically. We evaluate the effectiveness of this function through an experiment for 42 students who are currently taking the Java programming class.

An extension of clustering algorithm for smart-antenna use in wireless mesh networks

Shigeto Tajima, Nobuo Funabiki, Shigeru Tomisato, Masaharu Hata, Teruo Higashino

1st IEEE Global Conference on Consumer Electronics 2012, GCCE 2012 638 - 642 2012

Language：English

As a scalable cost-efficient Internet-access network, we have studied the Wireless Internet-access Mesh Network (WIMNET) that is composed of multiple access point (APs) connected through the Wireless Distribution System (WDS). Because all the traffics pass through an Internet Gateway (GW), the resolution of link congestions around the GW is very important. To solve this problem, we have proposed a clustering algorithm to partition the APs into a set of clusters where each cluster consists of the APs sharing the same GW. In addition, we have considered the use of a smart antenna at a special AP called a Smart AP (SAP). In this paper, we extend this clustering algorithm for smart antenna use at SAPs. Besides, we investigate the link activation strategy for the smart antenna, because it allows a variety of link activations for packet transmissions. We evaluate the effectiveness through simulations using the WIMNET simulator. © 2012 IEEE.

DOI： 10.1109/GCCE.2012.6379939

A proposal of access-point aggregation approach for multiple wireless local area networks

Nobuo Funabiki, Md. Ezharul Islam, Toru Nakanishi, Kan Watanabe

4th International Workshop on Virtual Environment and Network-Oriented Applications (VENOA 2012) 668 - 673 2012

A pairing-based anonymous credential system with efficient attribute proofs

Amang Sudarsono, Toru Nakanishi, Nobuo Funabiki

Journal of Information Processing 20 ( 3 ) 774 - 784 2012

Language：English

To enhance user privacy, anonymous credential systems allow the user to convince a verifier of the possession of a certificate issued by the issuing authority anonymously. The typical application is the privacy-enhancing electronic ID (eID). Although a previously proposed system achieves the constant complexity in the number of finiteset attributes of the user, it requires the use of RSA. In this paper, we propose a pairing-based anonymous credential system excluding RSA that achieves the constant complexity. The key idea of our proposal is the adoption of a pairing-based accumulator that outputs a constant-size value from a large set of input values. Using zero-knowledge proofs of pairing-based certificates and accumulators, any AND and OR relation can be proved with the constant complexity in the number of finite-set attributes. We implement the proposed system using the fast pairing library, compare the efficiency with the conventional systems, and show the practicality in a mobile eID application. © 2012 Information Processing Society of Japan.

DOI： 10.2197/ipsjjip.20.774

A proposal of CSMA fixed backoff-time switching protocol and its implementation on QualNet simulator for wireless mesh networks

Sritrusta Sukaridhoto, Nobuo Funabiki, Toru Nakanishi, Kan Watanabe

Proceedings - 26th IEEE International Conference on Advanced Information Networking and Applications Workshops, WAINA 2012 520 - 525 2012

Language：English

As an inexpensive and scalable Internet access network, we have studied the architecture, protocols, and design optimizations of the Wireless Internet access Mesh Network (WIMNET). WIMNET is composed of multiple access points (APs) that are connected through wireless links. Previously, we have proposed the concept of the CSMA-based Fixed Back off-time Switching (CSMA-FBS) method for WIMNET to improve the performance by giving necessary link activation chances for multi-hop communications. In this paper, we propose a protocol for this CSMA-FBS method implement able on APs, and its actual implementation on the QualNet simulator for evaluations in realistic network environments. The simulation results in two network topologies confirm the effectiveness of our proposal. © 2012 IEEE.

DOI： 10.1109/WAINA.2012.69

An online fill-in-the-blank problem function for learning reserved words in Java programming education

Nobuo Funabiki, Yousuke Korenaga, Yukiko Matsushima, Toru Nakanishi, Kan Watanabe

Proceedings - 26th IEEE International Conference on Advanced Information Networking and Applications Workshops, WAINA 2012 375 - 380 2012

Authorship：Lead author Language：English

The Java programming education to students has been held in a lot of universities and professional schools due to the reliability, portability, and easy learning. To assist this education, our group has developed a Java programming learning system based on the test-driven development method. However, this Web system targets students who have studied Java to some extent. In this paper, we propose a fill-in-the-blank problem function for this system to assist the learning of the Java reserved words by novice Java learners. Our function consists of a teacher service process and a student service process. By the former one, a teacher can generate a fill-in-the-blank problem easily by blanking the specified reserved words randomly from a sample Java code in the database. By the latter one, a student can repeatedly submit answers of a problem until all the questions are correctly solved for self-study. The function is implemented on an existing Web system and is applied to students who are currently learning Java. The questionnaire result confirms the effectiveness of our proposal. © 2012 IEEE.

DOI： 10.1109/WAINA.2012.64

An Extension of Routing Tree Algorithm Considering Link Speed Change in IEEE 802.11n Protocol for Wireless Mesh Network

Nobuo Funabiki, Wataru Maruyama, Toru Nakanishi, Kan Watanabe

2012 9TH INTERNATIONAL CONFERENCE ON UBIQUITOUS INTELLIGENCE & COMPUTING AND 9TH INTERNATIONAL CONFERENCE ON AUTONOMIC & TRUSTED COMPUTING (UIC/ATC) 600 - 605 2012

Authorship：Lead author Language：English Publisher：IEEE COMPUTER SOC

As an inexpensive, flexible, and scalable Internet-access network, we have studied architecture, protocols, and design optimizations of the Wireless Internet-access Mesh NETwork (WIMNET). WIMNET consists of multiple access-points (APs) as wireless routers that are connected through wireless links. One AP acts as a gateway (GW) to the Internet, where any host must reach there for the Internet access through multi-hop communications between APs. Because a lot of traffic must be handled by these links, the latest IEEE 802.11n protocol should be adopted to provide high-speed communications. In this paper, we first show that our throughput measurement results using commercial products implementing this protocol, reveal the quick drop of the throughput as the increase of the link distance. Then, we present extensions of our previously proposed routing tree algorithm for WIMNET and the WIMNET simulator in considering this link speed change by the distance. We verify the effectiveness of our proposals through simulations in four cases with different topologies.

DOI： 10.1109/UIC-ATC.2012.162

A Lattice Implementation of High-precision IIR Filter for X-ray CT Reconstruction

Kazuhisa Hayashi, Hiroshi Tsutsu, Yoshitaka Morikawa, Nobuo Funabiki

INTERNATIONAL MULTICONFERENCE OF ENGINEERS AND COMPUTER SCIENTISTS, IMECS 2012, VOL I 751 - 756 2012

Authorship：Lead author Language：English Publisher：INT ASSOC ENGINEERS-IAENG

The authors previously proposed forward and backward one round (FBOR) method to accelerate the filtering process by realizing the discrete Hilbert transform (DHT) function using an IIR filter in the convolution backprojection (CB) method that is a typical reconstruction algorithm for the X-ray CT. The FBOR method cascades causal and anticausal allpass filters to realize the linear phase DHT, and implements them by parallel ladders of allpass filters. Unfortunately, this method has to adopt the DHT that has the brickwall transition at the zero frequency and thus, requires high sensitivity coefficients in order to reduce distortions of a reconstructed image. As a result, it needs to rely on double precision floating points to avoid cancellations of significant digits. In this paper, we propose a successive-scan one-round (SSOR) method of implementing the DHT by cascading primary lattice allpass filters that allows the use of single precision floating points. We confirm the effec-tiveness of our proposal through simulations.

Modeling and Performance Evaluation of Colluding Attack in Volunteer Computing Systems

Kan Watanabe, Nobuo Funabiki, Tom Nakanishi, Masaru Fukushi

INTERNATIONAL MULTICONFERENCE OF ENGINEERS AND COMPUTER SCIENTIST, IMECS 2012, VOL II 1658 - 1663 2012

Language：English Publisher：INT ASSOC ENGINEERS-IAENG

This paper proposes a model of a colluding attack in Volunteer Computing (VC), where some of participants are unreliable and may return incorrect results. The colluding attack is one of the most important issues to realize reliable VC because it may ruin the most basic assumption, i.e. "the majority in voting is correct". Especially, check-by-voting archives the largest efficiency by sorting reliable participants based on whether their results are the majority or not. Thus, if some incorrect results become the majority by colluding attack, it may have significant impacts on check-by-voting. In this paper, we perform a Monte Carlo simulation of VC using the proposed colluding model and evaluate the sabotage-tolerance performance of voting methods. Simulation results show that check-by-voting works well if colluding attack happens.

A Proposal of an Access-Point Aggregation Algorithm for Wireless Local Area Networks

ISLAM Md. EZHARUL, FUNABIKI Nobuo, NAKANISHI Toru, WATANABE Kan

IEICE technical report 111 ( 344 ) 1 - 6 2011.12

Language：English Publisher：The Institute of Electronics, Information and Communication Engineers

Nowadays, multiple wireless local area networks (WLANs) have been deployed in the same building of an institute including a company and a university. Usually, their wireless acess-points (APs) have been independently managed and operated by different groups in the building such as departments or laboratories. As a result, a WLAN user host can detect signals from multiple APs, which may increase the interference and degrade the communication performance. Thus, the minimization of the number of active physical APs by aggregating the allocated APs in the field by introducing virtual APs becomes one of the major challenges in WLANs. In this paper, we formulate this AP aggregation problem for WLANs of aggregating the APs into the minimum number of active APs, and propose its heuristic algorithm that is composed of four phases. The effectiveness of our proposal has been verified through simulations in two instances.

A Clustering Algorithm for WDS Clusters with Two Access-Points Using Smart Antenna in Wireless Mesh Networks

TAJIMA Shigeto, FUNABIKI Nobuo, TOMISATO Shigeru, HATA Masaharu, HIGASHINO Teruo

Technical report of IEICE. RCS 111 ( 345 ) 81 - 86 2011.12

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

As a scalable Internet access network, we have studied the Wireless Internet-access Mesh Network (WIMNET) that is composed of multiple access point (APs) connected through the Wireless Distribution System (WDS). For large scale WIMNET, because the traffic through the Internet gateway (GW) becomes very high, it is composed of multiple WDS clusters where one cluster consists of APs sharing the same GW. Even in this hierarchial WIMNET, links around the GW are still crowded in each WDS cluster and may become bottlenecks of whole communications. Hence, we have proposed the adoption of a Smart AP (SAP) using the smart antenna technology for bandwidth enhancements. In this paper, we propose an extension of our WDS clustering algorithm for WIMNET such that the GW and one adjacent AP are selected as SAPs in each WDS cluster. Through simulations using grid topology instances, we verify the effectiveness of our algorithm extension.

A Proposal of Efficient Range Proof Protocol for Anonymous Credential System

IKEDA Daiki, NAKANISHI Toru, FUNABIKI Nobuo

Technical report of IEICE. ISEC 111 ( 337 ) 7 - 14 2011.12

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

An anonymous credential system allows a user to convince a verifier of the possession of user's attributes anonymously. A range proof protocol in an anonymous credential system is the protocol where the user can show that user's attribute belongs to a certain integer range without revealing the attribute. In the previous scheme, while the constant computational complexity is achieved, the size of the public parameters depends on the number of the attributes N. This paper proposes a range proof protocol with O (logTV) public parameter size. We also implement and evaluate it.

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