• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2207-2216
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• 2012

Recently, wireless Internet environment with mobile phones and wireless sensor networks with severe resource restrictions have been actively studied. Moreover, an overall security issues are essential to build a reliable and secure sensor network. One of secure solution is to develop a fast cryptographic algorithm for data encryption. Therefore, we propose a 128-bit stream cipher, AA128 which has efficient implementation of software and hardware and is suitable for real-time applications such as wireless Internet environment with mobile phones, wireless sensor networks and Digital Right Management (DRM). AA128 is stream cipher which consists of 278-bit ASR and non-linear transformation. Non-linear transformation consists of Confusion Function, Nonlinear transformation(SF0 ~ SF3) and Whitening. We show that the proposed stream cipher AA128 is faster than AES and Salsa20, and it satisfies the appropriate security requirements. Our hardware simulation result indicates that the proposed cipher algorithm can satisfy the speed requirements of real-time processing applications.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.361-365
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• 2010

In recent years, social networks come into the spotlight as the important ways to find people or share information. Especially, existing social network services based on the Internet, such as Facebook.com and Cyworld.com, are now extended into the mobile environment. A mobile phone easily collects the personal information since it is carried by the user at all times, and various types of data can be gathered together with the advance of sensor technologies. These features differentiate the mobile social network services from the previous Internet-based services. In this paper, we estimate the user's mobile social contexts like closeness and relationship between the user and surrounding people using Bayesian networks. The mobile social contexts can be employed as important information for providing mobile social network services, and experimental results on real world data have verified their possibilities.

• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.218-225
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• 2007

As the research on home network technologies, sensor network technologies, and ubiquitous network technologies makes rapid progresses, wireless ad-hoc network have attracted a lot of attention. A wireless mobile ad-hoc network is a temporary network formed by a collection of wireless mobile nodes without the aid of any existing network infrastructure or centralized administration, and it is suitable for ubiquitous computing environments. In this paper, we suggest an extension scheme of a wireless mobile ad-hoc network based on limited multiple paths source routing protocol. This scheme reduces the overhead of route re-establishment and re-registration by maintaining link/node non-disjoint multiple paths between mobile hosts in a wireless mobile ad-hoc network or a mobile host in a wireless mobile ad-hoc network and a base station supporting fixed network services. By maintaining multiple paths, our scheme provides short end-to-end delay and is reliable extension scheme of a wireless mobile ad-hoc network to a fixed network. In this paper, our simulations show that our scheme outperforms existing schemes with regards to throughput and end-to-end delay. Also we show that our scheme outperforms multi-paths approach using disjoint routes with regards to routing overhead.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.476-479
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• 2003

Recently, Bluetooth has been regarded as a new technology for short-range wireless connection. Although initial application of Bluetooth technology has been focused mainly on replacing cables between hand-held devices due to a limited packet size and short-range, general wireless telecommunication such as PAN and Ad hoc networks via Bluetooth-equipped devices is expected to be one of the most popular applications. Wireless equipments have been used to exchange data between host and mobile unit. The exchanging data may be several bytes of control command and the value of sensors with ultra-sonic, vision sensor, and encoder from mobile robot. However, most wireless equipments have some drawbacks such as lack of authentication, large size and high price. On the other hand, the benefits of Bluetooth are small size, low power, low price except short-range. Especially, there are some difficulties when wireless modules are used in indoor environments. In this paper, a method of using wire network in Bluetooth network is investigated as a solution to overcome the short-range problem of Bluetooth and difficulty in indoor environment.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.711-717
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• 2007

Location information will become increasingly important for future Pervasive Computing applications. Location tracking system of a moving device can be classified into two types of architectures: an active mobile architecture and a passive mobile architecture. In the former, a mobile device actively transmits signals for estimating distances to listeners. In the latter, a mobile device listens signals from beacons passively. Although the passive architecture such as Cricket location system is inexpensive, easy to set up, and safe, it is less precise than the active one. In this paper, we present a passive location system using Cricket Mote sensors which use RF and ultrasonic signals to estimate distances. In order to improve accuracy of the passive system, the transmission speed of ultrasound was compensated according to air temperature at the moment. Upper and lower bounds of a distance estimation were set up through measuring minimum and maximum distances that ultrasonic signal can reach to. Distance estimations beyond the upper and the lower bounds were filtered off as errors in our scheme. With collecting distance estimation data at various locations and comparing each distance estimation with real distance respectively, we proposed an equation to compensate the deviation at each point. Equations for proposed algorithm were derived to calculate relative coordinates of a moving device. At indoor and outdoor tests, average location error and average location tracking period were 3.5 cm and 0.5 second, respectively, which outperformed Cricket location system of MIT.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.116-123
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• 2013

In mobile healthcare applications, the reliable transmission of the bio-data is very important. In this article, we present a reliable bio-data transmission technique for mobile healthcare monitoring service at 6LoWPAN multi-hop wireless networks. In particular, we expand IEEE 11073-20601 protocol, and propose the reliable path construction for 6LoWPAN aimed to reliably provide mobile healthcare service over wireless sensor network, using IPv6 network. 6LoWPAN is recognized possibility because it is agree with sensor network by raising Adaptation layer on the MAC layer to transmit IPv6 packets. In this article proposed minimize the algorithm complexity and reliability routing protocol because the 6LoWPAN devices are suitable for low cost, small size and battery that can be used to health care system environment. And detailed procedures and algorithms are presented. We the proposed method to prove the superiority of using NS-3 for compareing with AODV protocol.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.744-747
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• 2008

Sensor networks will play an important role in the next generation pervasive computing. But its characteristic of wireless communication brings a peat challenge to the security measures used in the communication protocols. These measures are different from conventional security methods. In this paper, we proposed a security architecture for self-organizing mobile wireless sensor networks. It can prevent most of attacks based on intrusion detection.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.51-58
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• 2010

In data collection using a mobile sink, the time that sensor nodes are included in its communication radius is not uniform. The data collection schedule in non-uniform time is needed between a mobile sink and sensor nodes for efficient data collection. The existing data collection schemes using a mobile sink considered staying time in its communication range and data collected by the mobile sink. However, they did not consider the characteristics of data collected in sensor networks. In this paper, we propose a TDMA based schedule scheme that consists of the data collection period by each sensor nodes and the data collection period between a mobile sink and sensor nodes. Moreover, we propose a data collection scheme considering the variability of data in sensor networks. The proposed data collection scheme collects only data that changed larger than the threshold set by the user. In order to show the superiority of the proposed scheme, we compare it with DWEDF that aims to collect data uniformly. As a result, our experimental results show that the proposed scheme reduces about 23% energy consumption and the data collection failure of sensor nodes over the DWEDF.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.1-8
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• 2008

If a sink can move in sensor networks, the routing change can be more occur. If the sink has the mobility, it moves in sensor network area so that the connection between the sink system and sensor nodes will be changed continuously. Hence, the overhead can occur cased by the many routing changed. Therefore, the dynamic routing scheme is needed to support the mobile sink connection. In this paper, we propose the previous connection assignment scheme. The mobile sink can have low cost overhead from calculating dynamic rerouting that it determines the new virtual path before the physical path setup.

• 한국IT서비스학회:학술대회논문집
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• 2007.11a
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• pp.280-285
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• 2007

다가올 유비쿼터스 시대를 선도할 기술 중 하나인 USN(Ubiquitous Sensor Network)은 산업 전반에 커다란 변화를 가져올 것으로 기대된다. USN은 각종 센서 노드로부터 사물 및 환경 정보를 감지, 저장, 가공, 통합하고 상황인식 정보 및 지식 콘텐츠 생성을 통하여 언제, 어디서. 누구나 원하는 맞춤형 서비스를 자유로이 이용할 수 있는 첨단 지능형사회의 기반 인프라이다. USN과 더불어 이를 활용하기 위한 USN 어플리케이션의 개발들이 늘고 었으며 이에 USN 미들웨어의 필요성 또한 증가하고 있다. USN 디렉토리 서비스는 USN 미들웨어를 구성하는 핵심 서비스 중 하나이며, 지역적으로 분산된 USN 자원에 대한 정보를 관리하고 USN 자원에 대한 검색을 실시간으로 제공하는 서비스이다. USN 자원은 고정된 자원과 이동성을 지닌 자원으로 나눌 수 있다. 하지만 현재 이동성을 지닌 센서 노드(Mobile Sensor Node)를 지원할 수 있는 USN 디렉토리 서비스는 보이지 않고 있다. 본 논문은 이러한 Mobile Sensor Node의 특성을 지원하는 USN 디렉토리 서비스의 모델들을 제시하고 그에 대한 설계 및 구현을 논한다.