• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1059-1067
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• 2006

AODV(Ad-hoc On-demand Distance Vector) routing protocol was devised for use of mobile nodes in Ad-hoc network. When we use the AODV routing protocol in Ad-hoc networks with high mobility, disturbance of optimized route path and link break occur. In order to solve the shortcomings, this paper proposes a new routing protocol in which new routing control messages are added to the existing AODV. The proposed protocol minimizes link break and transmission delay while is able to secure the optimized route path constantly in changes of network topology The performance of the proposed routing protocol was evaluated by using us2 network simulator. The actual Ad-hoc network test bed provides us the most reliable experimental data for Ad-hoc networks. In order to support this experimental environment, the dissertation also developed an efficient embedded system on which AODV routing protocol, NAT, Netfilter can run and other event message can be verified without declining efficiency. The correct operation of AODV routing protocol has been verified in both the Ad-hoc network test bed in which the embedded system was used, and Ad-hoc networks linked with Ethernet backbone network.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.238-248
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• 2007

As the demand of employing various PC software on mobile embedded devices which have limited storages has been increased, software streaming services are needed. However it takes too much time to launch software on them because it is transferred through wireless networks. To address this problem, prefetch algorithms are needed. We examined 'Last successor (LS)' algorithm and PPM-based prefetch algorithm as prefetch algorithms for software streaming services. We present 'Probability-base Multi Successor (PMS)' algorithm which is contrived through analyzing evaluations of previous algorithms and characteristics of software streaming services. While LS has one successor per each block, PMS has N successors based on probability which is calculated by PPM-based prefetch algorithm. The hit rate of PMS is similar to that of PPM-base prefetch algorithm and the space overhead is similar to that of LS. We can get good efficiency at the point of memory usage when PMS is applied to software streaming services.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.42-48
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• 2016

Extensive research effort has been made during the last decade to utilize wireless smart sensors for evaluating and monitoring structural integrity of civil engineering structures. The wireless smart sensor commonly has sensing and embedded computation capabilities as well as wireless communication that provide strong potential to overcome shortcomings of traditional wired sensor systems such as high equipment and installation cost. However, sensor malfunctioning particularly in case of long-term monitoring and unreliable wireless communication in harsh environment are the critical issues that should be properly tackled for a wider adoption of wireless smart sensors in practice. This study presents a wireless smart sensor network(WSSN) that can estimate unmeasured responses for the purpose of data recovery at unresponsive sensor nodes. A software program that runs on WSSN is developed to estimate the unmeasured responses from the measured using the Kalman filter. The performance of the developed network software is experimentally verified by estimating unmeasured acceleration responses using a simply-supported beam.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2593-2600
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• 2010

A growth of mobile and wireless networking technologies have enabled mobile ad hoc networks applicable to a wide range of areas. This paper analyzes dynamics of network transport performance with respect to dynamics of network states especially for the mobile ad hoc networks called MANET. The edge cost based modeling methodology is adopted for the analysis, which can express well the characteristics of MANET. In this methodology the network state at arbitrary time can be specified as one of four edge states. We extracts ten target network scenarios for the simulation analysis by employing not only the Real Edge/Infinity Edge concept but also interworking functionality between different transport protocols. Then we could acquire from simulation of them with the DEVSim++ engine that the more sorts of transport protocols and the more number of interworking nodes are included in the network, the more contribution is for improving network transport performance.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.2
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• pp.48-62
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• 2006

In recent years, wireless sensor networks(WSNs) have emerged as a new fast-growing application domain for wireless distributed computing and embedded systems. Recent Progress in computer and communication technology has made it possible to organize wireless sensor networks composed tiny sensor nodes. Furthermore, ad-hoc network protocols do not consider the characteristics of wireless sensor nodes, making existing ad-hoc network protocols unsuitable for the wireless sensor networks. First, we propose power-aware routing protocols based on energy-centered routing metrics. Second, we describe power management techniques for wireless sensor nodes using the spatial locality of sensed data. Many nodes can go into a power-down mode without sacrificing the accuracy of sensed data. Finally, combining the proposed techniques, we describe an overall energy-efficient protocol for data collection. Experimental results show that the proposed routing protocol can extend the routing path lifetime more than twice. The average energy consumption per sensing period is reduced by up to 30%.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1058-1065
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• 2004

Embedded system is widely used in various applications from simple monitor to a set-top box with CPU, memory and hard disk drives. Specially, embedded OS is ported in moveable or small machinery since it ordinarily transmits multimedia data. In this paper, we propose Null copy scheme on the embedded linux system for multimedia service, which can reduce memory copy overhead from user address space to kernel one, and vice versa. Since embedded system for networked multimedia service has low level computing power as well as memory, the Null copy scheme can provide more improved QoS. Our image transmission experiment results on embedded linux target board(CPU utilization an Deadline miss rates) installed a web camera have shown that the proposed scheme can increase fast response and lower CPU overhead.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.125-131
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• 2009

In this paper, we proposed the remote visual monitoring system on mobile robot platform. The proposed system is composed of ARM9 core PXA255 processor, micro CMOS camera and wireless network and the captured visual image is transmitted via 803.11b/g wireless LAN(WLAN) for remote visual monitoring operations. Robot platform maneuvering command is transmitted via WLAN from host and the $640{\times}480$, $320{\times}240$ pixel fixed visual image is transmitted to host at the rate of $3{\sim}10$ frames per second. Experimental system is implemented on Linux OS base and tested for remote visual monitoring operation and verified the proposed objects.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2257-2258
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• 2008

본 논문에서는 최근 자신의 몸과 건강에 대한 관심이 증가함에 따라 WSN과 ZIgbee를 이용하여 언제 어디서나 운동하는 사람(이하 사용자)의 건강상태를 체크할 수 있는 헬스케어시스템을 구현하였다. 구현된 시스템은 사용자를 인식하는 RFID리더기와 운동량을 측정하기 위한 센서그룹과 사용자의 혈압, 심전도, 체온, 맥박 등을 수집하는 바이오센서, 센싱 된 정보를 수집하여 전달하는 게이트웨이, 사용자정보, 수집정보와, 측정정보를 저장하는 헬스케어관리서버 그리고 측정결과를 사용자가 모니터할 수 있는 모니터프로그램으로 구성된다. 구현된 센서노드는 Zigbee 프로토콜을 이용하여 센서네트워크를 구성한다. 그리고 리눅스 기반의 임베디드 시스템을 윈도우 기반에서 사용하기 위해 Cygwin을 이용한다. 수집된 정보는 USN과 WSN 로 실시간으로 전송된다. 이 전송된 결과 값을 헬스케어관리서버에서 저장, 관리하며 긴급 상황 발생 시 모니터를 통해 경보음을 내보내는 동시에, 사용자의 상태를 병원이나 소방서와 같은 응급처리 센터에 전송하도록 설계되었다. 구현결과 Zigbee 프로토콜과 WSN을 이용하여 사용자인식기반의 헬스케어시스템의 구현됨을 확인할 수 있었다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.3
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• pp.459-469
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• 2023

The number of IoT devices is explosively increasing due to the development of embedded equipment and computer networks. As a result, cyber threats to IoT are increasing, and currently, malicious codes are being distributed and infected to IoT devices and exploited for DDoS. Currently, IoT devices that are the target of such an attack have various installation environments and have limited resources. In addition, IoT devices have a characteristic that once set up, the owner does not care about management. Because of this, IoT devices are becoming a blind spot for management that is easily infected with malicious codes. Because of these difficulties, the threat of malicious codes always exists in IoT devices, and when they are infected, responses are not properly made. In this paper, we will design an malware detection system for IoT in consideration of the characteristics of the IoT environment and present detection rules suitable for use in the system. Using this system, it will be possible to construct an IoT malware detection system inexpensively and efficiently without changing the structure of IoT devices that are already installed and exposed to cyber threats.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.33-42
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• 2012

Rapid evolution of wired and wireless technologies results in various types of embedded systems, and the software to be embedded into those devices now needs the flexibility rather than the fixedness which was well-known property for the embedded software in the past. Mobile agent is one of the useful distributed technologies of reducing network load and latency because of its disconnected operations and high asynchrony. In this paper, a component-based mobile agent framework, called EmHUMAN, is designed and implemented for structural embedding into the devices showing different functions and resource constraints. It consists of 3 layers of components. Based on those components, a structural embedding, considering resource constraints of required functions, amount of storage space, computing power, network bandwidth, ${\ldots} $ etc can be performed. The components in each layer can be extended with addition of new components, removing some components and modifying components. EmHUMAN plays the role of a framework for developing mobile agent based distributed systems. It is also a mobile agent system by itself. EmHUMAN provides several utilities as built-in API's, and thus high effectiveness in programming mobile agents can be achieved.