Published papers

There are many challenges for Internet of Things (IoT) sensor networks including the lack of robust standards, diverse wireline and wireless connectivity, interoperability, security, and privacy. Addressing these challenges, the Institute of Electrical and Electronics Engineers (IEEE) P1451.0 standard defines network services, transducer services, transducer electronic data sheets (TEDS) format, and a security framework to achieve sensor data security and interoperability for IoT applications. This paper proposes a security solution for IEEE P1451.1.6-based sensor networks for IoT applications utilizing the security framework defined in IEEE P1451.0. The proposed solution includes an architecture, a security policy with six security levels, security standards, and security TEDS. Further, this paper introduces a new service to update access control lists (ACLs) to regulate the access for topic names by the applications and provides an implementation of the security TEDS for IEEE P1451.1.6-based sensor networks. The paper also illustrates how to access security TEDS that contain metadata on security standards to achieve sensor data security and interoperability.

This paper presents an expression of system connection considering transmission delay. In a research field of decentralized system or information system, the expression method of the system connection is a very important issue. Therefore, several expression methods of system connection have been proposed so far. However, those expressions are mainly based on binary operations without consideration for the transmission delays on connection paths although the concept of time is very important for expression of system connection. In this paper, expression methods of system connection considering transmission delays on the paths are proposed. Those expressions are based on exponential-type expression and can express both connections and transmission delays. Furthermore, the expression that can express connections, transmission delays, and past subsystems is also proposed. As one example of the application of proposed expressions, application for path selection of the design of network-based control system is described. © 2009 Wiley Periodicals.

In this paper, the estimation method of only gravity and the compensation method of only the disturbance caused by gravity are proposed. The proposed method is able to estimate gravity, even when the system has the unknown posture. The proposed method is based on the concept of "environment quarrier". Then, environment quarry is expanded to multilateral control. In this paper, two dummy robots that are the environment quarrier are implemented besides master-slave system, in order to abstract only gravity disturbance. The proposed method is adaptable, even when mass of master system differs from one of slave system. To verify the viability of the proposed method, experimental results are shown. © 2008 The Institute of Electrical Engineers of Japan.

This paper proposes four different methods for preventing cold boot attacks. These attacks exploit DRAM remanence to acquire private information stored in a memory. DRAM modules can keep stored values for many seconds without a power supply, in particular at low temperature. To address cold boot attacks, circuit-shorting method, SRAM preservation method and cell selection method are proposed. The integrated method of these methods is also proposed because these methods are independent and can be achieved together. These proposed methods are evaluated by using actual testbeds. © 2010 The Institute of Electrical Engineers of Japan.

Jitter is a technical issues of network bilateral control system. Hence, this paper proposed the jitter buffer method, which makes transmission delay constant. The validity of proposed system is confirmed by the experiments.