Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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Javaコードのクラス間連携理解のためのコアステートメント抽出アルゴリズム

石原信也, 舩曵信生

研究報告コンピュータと教育（CE） 2015 ( 10 ) 1 - 8 2015.2

Language：Japanese

Java プログラミング学習では，既存のソースコードを読み，その処理や構造を理解することが有効である．このコードリーディングをプログラミング教育に取り入れるためには，学習者がソースコードを理解したか否かを確認する方法が必要となる．そのため本グループでは，ソースコード中の肝要なステートメント（コアステートメント）を空欄とし，その記述を要求する，ステートメント空欄補充問題の提案と授業適用を行っている．本研究では，ソースコード中の空欄化すべきコアステートメント抽出アルゴリズムを提案する．本アルゴリズムでは，コアステートメントとして，1）要求仕様を充たすためのアルゴリズム要素，2）オブジェクト指向言語の特徴であるクラス間連携要素，3）データベースなど外部機能との連携要素，の 3 種類を想定し，それぞれの抽出法を定義している．提案アルゴリズムを実装し，5 つの Java ソースコードに適用して得られたコアステートメントを，Java 学習者による抽出結果と比較した．その結果，両者に高い一致がみられ，提案アルゴリズムの有効性が確認された．

Revocable Group Signatures with Compact Revocation List Using Accumulators

Toru Nakanishi, Nobuo Funabiki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E98A ( 1 ) 117 - 131 2015.1

Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A group signature scheme allows a group member to anonymously sign a message on behalf of the group. One of the important issues is the member revocation, and lots of revocable schemes have been proposed so far. A scheme recently proposed by Libert et al. achieves that O(1) or O(log N) efficiency of communication and computation except for the revocation list size (also the revocation cost), for the total number of members N and the number of revoked members R. However, since a signature is required for each subset separated from the set of non-revoked members, the size is about 900R Bytes in the 128-bit security. In the case of R = 100, 000, it amounts to about 80MB. In this paper, we extend the scheme to reduce the revocation list (also the revocation cost), by accumulating T subsets, which is signed for the revocation list. The revocation list size is reduced by 1/T. Unfortunately, the public key size, membership certificate size and the cost of a witness computation needed for signing increase related to T.

DOI： 10.1587/transfun.E98.A.117

Cross-Layer Selective Routing for Active Access-Point Minimization in Wireless Mesh Network

I-Wei Lai, Wen-Chung Kao, Nobuo Funabiki

2015 IEEE INTERNATIONAL CONFERENCE ON CONSUMER ELECTRONICS - TAIWAN (ICCE-TW) 482 - 483 2015

Language：English Publisher：IEEE

A Wireless Internet-access Mesh NETwork (WIMNET) provides the scalable and reliable internet access through the multiple access points (APs) and wireless relay communications. In particular, by redundantly deploying APs in the network field, the WIMNET becomes robust to the link or AP failure. However, these redundant APs increase the power consumption, and thus the number of active APs should be minimized by the selective routing without loss of the transmission performance. In this work, we propose to reinvent such selective routing algorithm by exploiting physical-layer technologies. An exemplar numerical simulation demonstrates that this cross-layer selective routing can further minimize the number of APs, leading to less operational costs in WIMNET.

DOI： 10.1109/ICCE-TW.2015.7217010

An Operator Fill-in-blank Problem for Algorithm Understanding in Java Programming Learning Assistant System

Nobuo Funabiki, Shin Sasaki, Ta Na, Wen-Chung Kao

2015 IEEE 4TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE) 346 - 347 2015

Authorship：Lead author Language：English Publisher：IEEE

A Web-based Java Programming Learning Assistant System (JPLAS) has been developed to help novice students studying Java programming through self-learning. As one function, JPLAS provides the fill-in-blank problem that requests filling in the blank elements in a given code with several blanks. Currently, reserved words, identifiers, or control symbols can be blanked to have unique correct answers, which may be solved without reading the code carefully. In this paper, we propose to additionally blank operators in conditional expressions of core statements in the code so that students can understand the structure to realize the specification. For preliminary evaluations, we generated six operator fill-in-blank problems, and assigned them to students where the number of answer submissions per blank has increased from that of conventional problems.

DOI： 10.1109/GCCE.2015.7398539

A proposal of statement fill-in-blank problem using program dependence graph in Java programming learning assistant system

Nobuya Ishihara, Nobuo Funabiki, Wen-Chung Kao

Information Engineering Express 1 ( 3 ) 19 - 28 2015

A proposal of value trace problem for algorithm code reading in Java programming learning assistant system

Khin Khin Zaw, Nobuo Funabiki, Wen-Chung Kao

Information Engineering Express 1 ( 3 ) 9 - 18 2015

A Worker Implementation on Windows OS for User-PC Computing System

Nobuo Funabiki, Yusuke Asai, Yuuki Aoyagi, Wen-Chung Kao

PROCEEDINGS OF 2015 THIRD INTERNATIONAL SYMPOSIUM ON COMPUTING AND NETWORKING (CANDAR) 279 - 282 2015

Authorship：Lead author Language：English Publisher：IEEE

Previously, we have proposed and implemented the User-PC computing (UPC) system as a highly parallel computing platform using idling CPU cycles in members' personal computers (PCs) of the same organization such as a laboratory in a university. This implementation for both the UPC master and the UPC worker covers only Linux OS. However, currently a lot of PCs adopt Windows OS. In this paper, we present an implementation of the UPC worker for Windows OS based on the implementation for Linux OS. During the implementation, we realize the CPU usage limitation and the automatic start-up of the worker program which can reduce loads for PC owner, aside from basic functions of master communications and job executions. Through evaluations, we conclude that the CPU usage rate does not exceed the given limitation except for starting time, and the job execution time on Windows is about twice the use of that on Linux.

DOI： 10.1109/CANDAR.2015.17

A Function for Generating Debugging Questions in a Java Programming Learning Assistant System

Shingo Yamaguchi, Takato Mohri, Nobuo Funabiki

2015 IEEE 4TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE) 350 - 353 2015

Language：English Publisher：IEEE

Today many universities offer courses for learning Java programming. Debugging cannot be avoided in programming. Nevertheless, there are not many chances for students to debugging programs, particularly written by another person. In this paper, for increasing that chance, we propose a function for generating a new kind of questions that are called debugging questions. A debugging question requires students to debug a program mixed with bugs. This function provides three ways of mixing bugs: deletion of reserved words, swapping of variables, and replacement by lists. We implemented this function into a Java programming learning assistant system, called JPLAS. We also discussed the usefulness by evaluating the function.

DOI： 10.1109/GCCE.2015.7398573

An Extension of Statement Fill-in-blank Problem in Java Programming Learning Assistant System

Nobuya Ishihara, Nobuo Funabiki, Ta Na, Wen-Chung Kao

2015 IEEE 4TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE) 354 - 358 2015

Language：English Publisher：IEEE

To assist Java programming studies, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). As one function in JPLAS, it provides a statement fill-in-blank problem that asks students to fill in proper statements to blanked ones in a Java code, so as to cultivate simultaneous code reading and writing abilities. Previously, we blanked only the core statement in a code with one class using the Program Dependence Graph (PDG), where we do not consider the features of object-oriented programming in Java that uses multiple classes and collaborations with other systems such as database. In this paper, we extend the statement fill-in-blank problem to deal with these features. We verify the effectiveness of our proposal through the Java programming course at our department.

DOI： 10.1109/GCCE.2015.7398543

Correlation Analysis of Fill-in-blank Problem Solutions to Final Programming Results in Java Programming Course

Ta Na, Nobuo Funabiki, Nobuya Ishihara, Wen-Chung Kao

2015 IEEE 4TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE) 348 - 349 2015

Language：English Publisher：IEEE

To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides fill-in-blank problems to study the Java grammar and fundamental programming by filling blank elements that are composed of reserved words, identifiers, and control symbols in a high-quality code. During the last semester, we assigned 121 problems with 1,552 questions to 46 students taking our Java programming course. In this paper, we analyze correlations of problem solving results of students to their final programming results.

DOI： 10.1109/GCCE.2015.7398542

Active Access-Point Configuration Algorithm with Dynamic Mobile Router Placement for Elastic WLAN System

Md. Selim Al Mamun, Md. Ezharul Islam, Nobuo Funabiki, I-Wei Lai

PROCEEDINGS OF 2015 THIRD INTERNATIONAL SYMPOSIUM ON COMPUTING AND NETWORKING (CANDAR) 246 - 252 2015

Language：English Publisher：IEEE

Recently, a variety of wireless access points (APs) have been deployed by many organizations to meet different traffic demands. Previously, we proposed an active AP configuration algorithm that activates or deactivates heterogeneous AP devices depending on the traffic demand and network topology, in order to realize the elastic Wireless Local-Area Network (WLAN) system. Unfortunately, in this algorithm, the locations of the mobile routers have been fixed as the algorithm input, although they can be placed flexibly as portable APs using cellular networks. In this paper, we consider the elastic WLAN system with mobile routers which can be placed flexibly. The dynamic mobile router placement is proposed for the active AP configuration algorithm to meet stringent traffic requirements. Specifically, if some hosts fail to meet the throughput requirements, the locations of additional mobile routers are dynamically determined by applying the Kmeans algorithm to maximize the number of those failed hosts in its coverage. The effectiveness of this location determination is demonstrated by numerical examples with three network scenarios.

DOI： 10.1109/CANDAR.2015.55

Extensions of Access-Point Aggregation Algorithm for Large-scale Wireless Local Area Networks

Islam Md. Ezharul, Funabiki Nobuo, Nakanishi Toru

IJNC 5 ( 1 ) 200 - 222 2015

Language：English Publisher：IJNC Editorial Committee

Recently, many organizations such as universities and companies have deployed wireless local area networks (WLANs) to cover the whole site for ubiquitous network services. In these WLANs, wireless access-points (APs) are often managed independently by different groups such as laboratories or departments. Then, a host may detect signals from multiple APs, which can degrade the communication performance due to radio interferences among them and increase operational costs. Previously, we proposed the AP aggregation algorithm to solve this problem by minimizing the number of active APs through aggregating them using the virtual AP technology. However, our extensive simulations in various instances found that 1) the minimization of active APs sometimes excessively degrades the network performance, and 2) the sequential optimization of host associations does not always reach optimal where slow links are still used. In this paper, we propose two extensions of the AP aggregation algorithm to solve these problems by 1) ensuring the minimum average throughput for any host by adding active APs and 2) further optimizing host associations by changing multiple hosts simultaneously in the host association finalization phase. We verify the effectiveness through simulations in four network instances using the WIMNET simulator.

DOI： 10.15803/ijnc.5.1_200

Other Link： https://jlc.jst.go.jp/DN/JLC/20005432460?from=CiNii

Practices of Fill-in-blank Problems in Java Programming Course

Nobuo Funabiki Tana, Nobuya Ishihara

2015 IEEE INTERNATIONAL CONFERENCE ON CONSUMER ELECTRONICS - TAIWAN (ICCE-TW) 120 - 121 2015

Language：English Publisher：IEEE

To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides fill-in-blank problems to study the Java grammar by filling blank elements in a high-quality code that are composed of reserved words, identifiers, and control symbols. A graph-based blank element selection algorithm has been proposed to automatically select as many blanks as possible that have grammatically correct unique answers. In this paper, we show and discuss their application results to a Java programming course in our department.

DOI： 10.1109/ICCE-TW.2015.7216810

Concept of User-PC Computing System

Nobuo Funabiki, Bongsu Kim, Yuki Aoyagi

2015 IEEE INTERNATIONAL CONFERENCE ON CONSUMER ELECTRONICS - TAIWAN (ICCE-TW) 480 - 481 2015

Authorship：Lead author Language：English Publisher：IEEE

The User-PC computing system (UPC) is a technology of realizing a parallel computing environment using idling computing resources (CPU cycles) in Personal Computers (PCs) of members in the same organization or group such as a laboratory in a university and a section in a company. UPC can resolve drawbacks in the registration of computing projects, the reliability of computing results, and the continuity of computations that may often happen in Volunteer Computing (VC) systems using voluntary PCs in the Internet. Thus, UPC can be easily and comfortably used by computing users. In this paper, we show the concept of UPC and preliminary evaluations.

DOI： 10.1109/ICCE-TW.2015.7217009

A proposal of graph-based blank element selection algorithm for Java programming learning with fill-in-blank problems

Tana, Nobuo Funabiki, Nobuya Ishihara

The International MultiConference of Engineers and Computer Scientists 2015 (IMECS 2015) 2015

Practices of Cooking-Step Scheduling Algorithm for Homemade Cooking

Yukiko Matsushima, Nobuo Funabiki

2015 IIAI 4TH INTERNATIONAL CONGRESS ON ADVANCED APPLIED INFORMATICS (IIAI-AAI) 500 - 505 2015

Language：English Publisher：IEEE

Homemade cooking is essential not only for keeping healthy and cost-efficient dietary lives but also for constructing good family relationships and identities. Previously, we proposed the cooking-step scheduling algorithm to help homemade cooking by finding a schedule of applying the cooking-steps for multiple dishes with minimal cooking time. In this algorithm, the cooking procedure for each dish is divided into a sequence of six types of cooking-steps to consider the constraints in cooks and cooking utensils in a kitchen. In this paper, we conduct practices of the algorithm in actually cooking dishes by following the generated schedules to show the effectiveness.

DOI： 10.1109/IIAI-AAI.2015.189

A Concept of Value Trace Problem for Java Code Reading Education

Khin Khin Zaw, Nobuo Funabiki

2015 IIAI 4TH INTERNATIONAL CONGRESS ON ADVANCED APPLIED INFORMATICS (IIAI-AAI) 253 - 258 2015

Language：English Publisher：IEEE

To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides the fill-in-blank problem to help novice students studying Java programming at home, where some elements in a high-quality code including reserved words, identifiers, and control symbols are blanked to be filled by students. Unfortunately, this problem may be solved without reading out the algorithm in the code if students are familiar with Java grammar to some extent. In this paper, to further cultivate the code reading capability of students, we propose a concept of the value trace problem to ask the actual values of important variables in a code implementing some fundamental data structure or algorithm. A value trace problem can be generated by: 1) selecting a high-quality class code for the algorithm to be studied, 2) making the main class to instantiate the class in 1) if it does not contain the main method, 3) adding the functions to output variable values in questions into a text file, 4) preparing the input file to the code in 3) if necessary, 5) running this code to obtain the set of variable values in the text file, 6) blanking some values from the text file to be filled by students, and 7) uploading the final code, the blanked text file, and the correct answer file into the JPLAS server, and adding the brief description on the algorithm for a new assignment. To verify the feasibility of this concept, we manually generated five problems and asked four students with high Java programming skills in our group to solve them. Then, we analyzed the difficulty of the value trace problem for Quick Sort.

DOI： 10.1109/IIAI-AAI.2015.188

A Proposal of Statement Fill-in-blank Problem in Java Programming Learning Assistant System

Nobuya Ishihara, Nobuo Funabiki

2015 IIAI 4TH INTERNATIONAL CONGRESS ON ADVANCED APPLIED INFORMATICS (IIAI-AAI) 247 - 252 2015

Language：English Publisher：IEEE

As a reliable, portable, and practical programming language, Java has been educated in many universities and professional schools. To assist Java educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides the element fill-in-blank problem and the code writing problem. The former problem is designed for novice students to study the grammar and writing style of Java by filling correct words to the blanks in a given Java code that are automatically marked by checking coincidences with correct ones. The latter problem is for students to study writing Java codes for specifications described in natural language that are automatically verified using the test-driven development (TDD) method. Unfortunately, the transition between two problems is not smooth due to the difference in difficulties. In this paper, we propose the statement fill-in-blank problem in JPLAS to fill the gap by asking students to write one whole statement in a code where the correctness is verified by the TDD method. The blank statement is selected by generating the Program Dependence Graph (PDG) of the code and finding the statement that has the largest dependence with other ones. We verify the effectiveness of our proposal through applications to the Java programming course in our department.

DOI： 10.1109/IIAI-AAI.2015.192

An Anonymous Reputation System with Reputation Secrecy for Manager

Toru Nakanishi, Nobuo Funabiki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E97A ( 12 ) 2325 - 2335 2014.12

Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In anonymous reputation systems, where after an interaction between anonymous users, one of the users evaluates the peer by giving a rating. Ratings for a user are accumulated, which becomes the reputation of the user. By using the reputation, we can know the reliability of an anonymous user. Previously, anonymous reputation systems have been proposed, using an anonymous e-cash scheme. However, in the e-cash-based systems, the bank grasps the accumulated reputations for all users, and the fluctuation of reputations. These are private information for users. Furthermore, the timing attack using the deposit times is possible, which makes the anonymity weak. In this paper, we propose an anonymous reputation system, where the reputations of users are secret for even the reputation manager such as the bank. Our approach is to adopt an anonymous credential certifying the accumulated reputation of a user. Initially a user registers with the reputation manager, and is issued an initial certificate. After each interaction with a rater, the user as the ratee obtains an updated certificate certifying the previous reputation summed up by the current rating. The update protocol is based on the zero-knowledge proofs, and thus the reputations are secret for the reputation manager. On the other hand, due to the certificate, the user cannot maliciously alter his reputation.

DOI： 10.1587/transfun.E97.A.2325

A Proposal of Blank Element Selection Algorithm for Java Programming Learning

Tana, FUNABIKI Nobuo, ISHIHARA Nobuya

Technical report of IEICE. SS 114 ( 271 ) 1 - 6 2014.10

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

The programming language Java has been widely used in industries and educated in educational institutes due to its excellent developing environments, reliability, and portability. To assist Java educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides the fill-in-blank problem for Java novice students to learn it by filling proper elements into blanks in a Java code. In the paper, we propose a blank element selection algorithm to find a feasible problem that has the unique solution for any blank. This algorithm first generates a simple graph such that a vertex represents a candidate element in the code and an edge is made between two vertices that can be blanked simultaneously. Then, it extracts a clique of the graph to maximize the number of feasible blanks. We applied the algorithm to 100 Java codes and checked the uniqueness of the solutions manually. The results show that by showing the execution results of the three codes, we confirmed the uniqueness of the solutions.

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