IEEEActa Medica Okayama2169-3536102022Two-Dimensional RSSI-Based Indoor Localization Using Multiple Leaky Coaxial Cables With a Probabilistic Neural Network2110921119ENJunjieZhuGraduate School of Natural Science and Technology, Okayama UniversityPengchengHouGraduate School of Natural Science and Technology, Okayama UniversityKentaNagayamaGraduate School of Natural Science and Technology, Okayama UniversityYafeiHouGraduate School of Natural Science and Technology, Okayama UniversitySatoshiDennoGraduate School of Natural Science and Technology, Okayama UniversityRianFerdianFaculty of Information Technology, Andalas UniversityReceived signal strength indicator (RSSI) based indoor localization technology has its irreplaceable advantages for many location-aware applications. It is becoming obvious that in the development of fifth-generation (5G) and future communication technology, indoor localization technology will play a key role in location-based application scenarios including smart home systems, manufacturing automation, health care, and robotics. Compared with wireless coverage using conventional monopole antenna, leaky coaxial cables (LCX) can generate a uniform and stable wireless coverage over a long-narrow linear-cell or irregular environment such as railway station and underground shopping-mall, especially for some manufacturing factories with wireless zone areas from a large number of mental machines. This paper presents a localization method using multiple leaky coaxial cables (LCX) for an indoor multipath-rich environment. Different from conventional localization methods based on time of arrival (TOA) or time difference of arrival (TDOA), we consider improving the localization accuracy by machine learning RSSI from LCX. We will present a probabilistic neural network (PNN) approach by utilizing RSSI from LCX. The proposal is aimed at the two-dimensional (2-D) localization in a trajectory. In addition, we also compared the performance of the RSSI-based PNN (RSSI-PNN) method and conventional TDOA method over the same environment. The results show the RSSI-PNN method is promising and more than 90% of the localization errors in the RSSI-PNN method are within 1 m. Compared with the conventional TDOA method, the RSSI-PNN method has better localization performance especially in the middle area of the wireless coverage of LCXs in the indoor environment.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama1051-82231422004The shielding effect of HTS power cable based on E-J power law654657ENDaisukeMiyagiSatoruIwataTomohiroWakatsukiNorioTakahashiShinjiToriiKiyotakaUedaKenjiYasudaA method for analysing the current distribution in high-T/sub c/ superconducting (HTS) power cable is examined by the aid of the novel use of anisotropic conductivity and 3-D finite element method considering E-J power law characteristic. The detailed current distribution in the cable is illustrated and the shielding effect of HTS shield layer with intervals is also examined. It is shown that AC losses in shield layer with intervals are increased when the interval between wires becomes large.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2640-009X20192019Speech-like Emotional Sound Generator by WaveNet143147ENKentoMatsumotoOkayama UniversitySunaoHaraOkayama UniversityMasanobuAbeOkayama UniversityIn this paper, we propose a new algorithm to generate Speech-like Emotional Sound (SES). Emotional information plays an important role in human communication, and speech is one of the most useful media to express emotions. Although, in general, speech conveys emotional information as well as linguistic information, we have undertaken the challenge to generate sounds that convey emotional information without linguistic information, which results in making conversations in human-machine interactions more natural in some situations by providing non-verbal emotional vocalizations. We call the generated sounds gspeech-likeh, because the sounds do not contain any linguistic information. For the purpose, we propose to employ WaveNet as a sound generator conditioned by only emotional IDs. The idea is quite different from WaveNet Vocoder that synthesizes speech using spectrum information as auxiliary features. The biggest advantage of the idea is to reduce the amount of emotional speech data for the training. The proposed algorithm consists of two steps. In the first step, WaveNet is trained to obtain phonetic features using a large speech database, and in the second step, WaveNet is re-trained using a small amount of emotional speech. Subjective listening evaluations showed that the SES could convey emotional information and was judged to sound like a human voice.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2015Sound collection and visualization system enabled participatory and opportunistic sensing approaches390395ENSunaoHaraMasanobuAbeNoboruSoneharaThis paper presents a sound collection system to
visualize environmental sounds that are collected using a crowd-sourcing approach. An analysis of physical features is generally used to analyze sound properties; however, human beings not
only analyze but also emotionally connect to sounds. If we want to visualize the sounds according to the characteristics of the listener,
we need to collect not only the raw sound, but also the subjective feelings associated with them. For this purpose, we developed a sound collection system using a crowdsourcing approach to collect physical sounds, their statistics, and subjective evaluations simultaneously. We then conducted a sound collection experiment using the developed system on ten participants.We collected 6,257 samples of equivalent loudness levels and their locations, and 516 samples of sounds and their locations. Subjective evaluations by
the participants are also included in the data. Next, we tried to visualize the sound on a map. The loudness levels are visualized as a color map and the sounds are visualized as icons which
indicate the sound type. Finally, we conducted a discrimination experiment on the sound to implement a function of automatic conversion from sounds to appropriate icons. The classifier is
trained on the basis of the GMM-UBM (Gaussian Mixture Model and Universal Background Model) method. Experimental results show that the F-measure is 0.52 and the AUC is 0.79.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2169-3536112023Reduction in Eddy Current Loss of Special Rectangular Windings in High-Torque IPMSM Used for Wind Generator47404751ENXianjiTaoGraduate School of Information and Technology, Hokkaido UniversityMasatsuguTakemotoGraduate School of Natural Science and Technology, Okayama UniversityRenTsunataGraduate School of Natural Science and Technology, Okayama UniversitySatoshiOgasawaraGraduate School of Information and Technology, Hokkaido UniversityA special rectangular winding structure, which has different cross-sectional shape but the same cross-sectional area for each turn, has been adopted in a high-torque IPMSM used for a wind generator to improve slot factor and heat dissipation. However, large eddy current loss occurs to the rectangular windings. According to this problem, this paper proposes three improvements to reduce the eddy current loss. Among them, removing a portion of windings and replacing a portion of windings with aluminum are discussed to realize a tradeoff between eddy current and copper losses. And adjusting the tooth-tip shape is discussed to suppress the magnetic flux passing through the windings by mitigating magnetic saturation around the tooth-tip. Additionally, manufacturing costs can also be reduced by adopting a portion of aluminum windings. Moreover, a 3-step-skewed rotor structure is discussed to reduce cogging torque and lower the start-up wind speed. And its influence on losses is also discussed. Furthermore, three models adopting round windings are made and discussed for comparison. The FEM (Finite Element Method) results show that compared with the three round windings models, the proposed model still has a better performance in the reduction of windings eddy current loss. Finally, a prototype machine is manufactured to verify the FEM results, and the experimental results show that the maximum efficiency of the prototype can exceed 97.5%.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama1520-92021922017Probing Software Engineering Beliefs about System Testing Defects: Analyzing Data for Future Directions5864ENAkitoMondenGraduate School of Natural Science and Technology, Okayama UniversityMasateruTsunodaDepartment of Informatics, Faculty of Science and Engineering, Kindai UniversityMikeBarkerGraduate School of Information Science, Nara Institute of Science and TechnologyKenichiMatsumotoGraduate School of Information Science, Nara Institute of Science and Technology Research findings are often expressed as short startling sentences or software engineering (SE) beliefs such as gabout 80 percent of the defects come from 20 percent of the modulesh and gpeer reviews catch 60 percent of the defectsh [2]. Such SE beliefs are particularly important in industry, as they are attention-getting, easily understandable, and thus practically useful. In this paper we examine the power of such SE beliefs to justify process improvement through empirical validation of selected beliefs related to the increase or decrease of defects in system testing. We explore four basic SE beliefs in data from two midsize embedded software development organizations in Japan, and based on this information, identify possible process improvement actions for each organization. Based on our study, even small and medium-sized enterprises (SMEs) can use this approach to find possible directions to improve their process, which will result in better products.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama0191-221642000Modeling uncertainty of large flexible structures with unknown modal parameters37803784ENJunImaiKiyoshiWadaA procedure for control-oriented modeling of uncertainty is proposed for large flexible structures. Techniques on quantification of errors in modal truncated nominal models are developed for the case where a finite number of upper and lower bounds of the unknown modal parameters are given. A feasible set of systems matching the conditions is introduced, and then error bounds covering the feasible set are established in the frequency domain. The bounds are easily checked using linear programming for any user-specified frequency. The feasibility of the proposed scheme is illustrated by numerical study on an ideal flexible beam example.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2018Mitigating Use-after-Free Attack Using Library Considering Size and Number of Freed Memory398404ENYuyaBanToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityUse-after-free (UAF) vulnerabilities, which are abused by exploiting a dangling pointer that refers to a freed memory, execute an arbitrary code. The vulnerability is caused by bug in a program. In particular, it is contained in a large scale program such as browser. HeapRevolver [1] [2], which prohibits freed memory area from being reused for a certain period, has been proposed. HeapRevolver in Windows uses the number of the freed memory areas for prohibiting as a trigger to release the freed memory area. In other words, HeapRevolver uses the number of the freed memory areas as a threshold for releasing. However, when the size of individual freed memory areas is large, the HeapRevolver on Windows increases the memory overhead. In this paper, we propose improved HeapRevolver for Windows considering the size and number of the freed memory areas. Improved HeapRevolver enables to prohibit the reuse of the certain number of the freed memory areas at any time via the size and number of the freed memory areas as a threshold. The evaluation results show that the improved HeapRevolver can prevent attacks that exploiting UAF vulnerabilities. In particular,
when the size of individual freed memory areas is small in the programs, it is effective to decrease the attack success rate. No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2020Method of Generating a Blacklist for Mobile Devices by Searching Malicious Websites20489448ENTakashiIshiharaGraduate School of Natural Science and Technology, Okayama UniversityMasayaSatoGraduate School of Natural Science and Technology, Okayama UniversityToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityAs mobile devices have become more popular, malware and attacks directed at them have significantly increased. One of the methods to attack mobile devices is redirecting a user to unwanted websites by unwanted page transition. One of the countermeasures against such attacks is to generate a blacklist of URLs and hostnames, which can prevent access to malicious websites. To generate a blacklist, first, malicious websites are collected in the web space. Then, URLs and hostnames of the malicious websites are added to the blacklist. However, URLs of the malicious websites are typically changed frequently; thus, it is necessary to keep track of the malicious websites and update the blacklist in a timely manner. In this study, we proposed a method to generate blacklists for mobile devices by searching malicious websites. The method collects many HTML files from the web space using a crawler and searches for HTML files that are highly likely to be malicious using keywords extracted from the known malicious websites to discover the new ones. Thus, new malicious websites can be added to the blacklist in a timely manner. Using the proposed method, we discovered malicious websites that were not detected by Google Safe Browsing. Moreover, the blacklist generated using the method had a high detection rate for certain malicious websites. This paper reports the design process and the results of the evaluation of the new method.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2379-18882016Memory Access Monitoring and Disguising of Process Information to Avoid Attacks to Essential Services635641ENMasayaSatoGraduate School of Natural Science and Technology, Okayama UniversityToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityHideoTaniguchiGraduate School of Natural Science and Technology, Okayama UniversityTo prevent attacks on essential software and to mitigate damage, an attack avoiding method that complicates process identification from attackers is proposed. This method complicates the identification of essential services by replacing process information with dummy information. However, this method allows attackers to identify essential processes by detecting changes in process information. To address this problems and provide more complexity to process identification, this paper proposes a memory access monitoring by using a virtual machine monitor. By manipulating the page access permission, a virtual machine monitor detects page access, which includes process information, and replaces it with dummy information. This paper presents the design, implementation, and evaluation of the proposed method.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2016KRGuard: Kernel Rootkits Detection Method by Monitoring Branches Using Hardware Features2226ENYoheiAkaoGraduate School of Natural Science and Technology, Okayama UniversityToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityAttacks on an operating system kernel using kernel rootkits pose a particularly serious threat. Detecting an attack is difficult when the operating system kernel is infected with a kernel rootkit. For this reason, handling an attack will be delayed causing an increase in the amount of damage done to a computer system. In this paper, we discuss KRGuard (Kernel Rootkits Guard), which is a new method to detect kernel rootkits that monitors branch records in the kernel space. Since many kernel rootkits make branches that differ from the usual branches in the kernel space, KRGuard can detect these differences by using hardware features of commodity processors. Our evaluation shows that KRGuard can detect kernel rootkits with small overhead.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2021Function for Tracing Diffusion of Classified Information to Support Multiple VMs with KVM352358ENKoheiOtaniGraduate School of Natural Science and Technology, Okayama UniversityToshikiOkazakiGraduate School of Natural Science and Technology, Okayama UniversityToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityHideakiMoriyamaDepartment of Creative Engineering, National Institute of Technology, Ariake CollegeMasayaSatoFaculty of Computer Science and Systems Engineering, Okayama Prefectural UniversityHideoTaniguchiGraduate School of Natural Science and Technology, Okayama UniversityTo handle information leaks caused by administrative errors or mishandling, a function for tracing the diffusion of classified information using a virtual machine monitor (VMM) was proposed. However, the proposed function has not been investigated in cases in which virtual machines (VMs) allocated by multiple virtual central processing units (vCPUs) are to be monitored. In addition, cases in which multiple VMs are monitored have not been examined. In this study, we describe the support of multiple VMs for the proposed VMM-based tracing function. We also show how to deal with VMs allocated by multiple vCPUs. Furthermore, we report the evaluation results from assessing the traceability of the improved proposed method and its overhead for classified information when a VM with multiple vCPUs is monitored.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2003Evaluating object and region of concentric electrode in bio-electrical impedance measurement282283ENYoshitakeYamamotoKiyokoShiraiNorikoGodaTakaoNakamuraToshimasaKusuharaHiroyukiOkudaConcentric electrode is easy to use and used widely for measuring bio-electrical impedance. But, its evaluating region was not investigated in detail. Then, the characteristics of concentric electrode were studied from various points of view. In case of use without electrode paste, impedance is determined with the contacting condition between electrode and skin surface over all frequency range. In case of use with electrode past, impedance is composed of stratum corneum in the frequency range of 20 Hz-1 kHz and is mainly composed of subcutaneous tissue in the range of 200 kHz-1 MHz. In the high frequency range, evaluating region of concentric electrode is the area less than the radius or the gap of center electrode.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama20082008Design and Evaluation of a Bayesian-filter-based Image Spam Filtering Method4651ENMasahiroUemuraGraduate School of Natural Science and Technology, Okayama UniversityToshihiroTabataGraduate School of Natural Science and Technology, Okayama UniversityIn recent years, with the spread of the Internet, the number of spam e-mail has become one of the most serious problems. A recent report reveals that 91% of all e-mail exchanged in 2006 was spam. Using the Bayesian filter is a popular approach to distinguish between spam and legitimate e-mails. It applies the Bayes theory to identify spam. This filter proffers high filtering precision and is capable of detecting spam as per personal preferences. However, the number of image spam, which contains the spam message as an image, has been increasing rapidly. The Bayesian filter is not capable of distinguishing between image spam and legitimate e-mails since it learns from and examines only text data. Therefore, in this study, we propose an anti- image spam technique that uses image information such as file size. This technique can be easily implemented on the existing Bayesian filter. In addition, we report the results of the evaluations of this technique.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2640-009X20192019DNN-based Voice Conversion with Auxiliary Phonemic Information to Improve Intelligibility of Glossectomy Patients' Speech138142ENHirokiMurakamiOkayama UniversityIn this paper, we propose using phonemic information in addition to acoustic features to improve the intelligibility of speech uttered by patients with articulation disorders caused by a wide glossectomy. Our previous studies showed that voice conversion algorithm improves the quality of glossectomy patients' speech. However, losses in acoustic features of glossectomy patients' speech are so large that the quality of the reconstructed speech is low. To solve this problem, we explored potentials of several additional information to improve speech intelligibility. One of the candidates is phonemic information, more specifically Phoneme Labels as Auxiliary input (PLA). To combine both acoustic features and PLA, we employed a DNN-based algorithm. PLA is represented by a kind of one-of-k vector, i.e., PLA has a weight value (<; 1.0) that gradually changes in time axis, whereas one-of-k has a binary value (0 or 1). The results showed that the proposed algorithm reduced the mel-frequency cepstral distortion for all phonemes, and almost always improved intelligibility. Notably, the intelligibility was largely improved in phonemes /s/ and /z/, mainly because the tongue is used to sustain constriction to produces these phonemes. This indicates that PLA works well to compensate the lack of a tongue.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama2013Access Control to Prevent Attacks Exploiting Vulnerabilities of WebView in Android OS16281633ENJingYuGraduate School of Natural Science and Technology, Okayama UniversityToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityAndroid applications that using WebView can load and display web pages. Furthermore, by using the APIs provided in WebView, Android applications can interact with web pages. The interaction allows JavaScript code within the web pages to access resources on the Android device by using the Java object, which is registered into WebView. If this WebView feature were exploited by an attacker, JavaScript code could be used to launch attacks, such as stealing from or tampering personal information in the device. To address these threats, we propose a method that performs access control on the security-sensitive APIs at the Java object level. The proposed method uses static analysis to identify these security-sensitive APIs, detects threats at runtime, and notifies the user if threats are detected, thereby preventing attacks from web pages.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama1550-445X2017Access Control for Plugins in Cordova-Based Hybrid Applications10631069ENNaokiKudoGraduate School of Natural Science and Technology, Okayama UniversityToshihiroYamauchiGraduate School of Natural Science and Technology, Okayama UniversityThomas H.AustinSan Jose State UniversityHybrid application frameworks such as Cordova allow mobile application (app) developers to create platformindependent apps. The code is written in JavaScript, with special APIs to access device resources in a platform-agnostic way. In this paper, we present a novel app-repackaging attack that repackages hybrid apps with malicious code; this code can exploit Cordovafs plugin interface to tamper with device resources. We further demonstrate a defense against this attack through the use of a novel runtime access control mechanism that restricts access based on the mobile userfs judgement. Our mechanism is easy to introduce to existing Cordova apps, and allows developers to produce apps that are resistant to app-repackaging attacks.No potential conflict of interest relevant to this article was reported.IEEEActa Medica Okayama22010A kinesthetic-based collaborative learning system for distributed algorithms97101ENHiroyukiNagatakiTaichiFujiiYukikoYamauchiHirotsuguKakugawaToshimitsuMasuzawaIn this paper, we present a learning support system DASE-E to help students understand fundamental concepts of distributed algorithms in computer science. DASE-E is a collaborative learning system, in which the task of students is
to devise a distributed algorithm. DASE-E offers a set of small wireless terminals with accelerometers. Each student plays the role of a process with a terminal, according to the algorithm that students devised. Each terminal enables a student to take physical actions that control the behavior of a process in the simulator. After the role playing simulation is finished, students discuss their activity played back on a screen. We implemented the system for learning distributed leader election algorithms, had a trial exercise in our research group, and we confirmed that it is effective to learn the critical part of distributed systems and algorithms.No potential conflict of interest relevant to this article was reported.