• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.27-35
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• 2007

When sensor networks are deployed in open environments, all the sensor nodes are vulnerable to physical threat. An attacker can physically capture a sensor node and obtain the security information including the keys used for data authentication. An attacker can easily inject false reports into the sensor network through the compromised node. False report can lead to not only false alarms but also the depletion of limited energy resource in battery powered sensor networks. To overcome this threat, Fan Ye et al. proposed that statistical on-route filtering scheme(SEF) can do verify the false report during the forwarding process. In this scheme, the choice of a security threshold value is important since it trades off detection power and energy, where security threshold value is the number of message authentication code for verification of false report. In this paper, we propose a fuzzy rule-based system for security threshold determination that can conserve energy, while it provides sufficient detection power in the SEF based sensor networks. The fuzzy logic determines a security threshold by considering the probability of a node having non-compromised keys, the number of compromised partitions, and the remaining energy of nodes. The fuzzy based threshold value can conserve energy, while it provides sufficient detection power.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.12-23
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• 2009

Sensor networks deployed in battlefields to support military operations or deployed in natural habitats to monitor the rare wildlifes must take account of protection of the location of valuable assets(i.e., soldiers or wildlifes) from an adversary or malicious tracing as well as the security of messages in transit. In this paper we propose a routing protocol GSLP(GPSR-based Source-Location Privacy) that is capable of enhancing the location privacy of an active source node(i.e., message-originating node) in the presence of multiple dormant sources(i.e., nodes lying nearby an asset whose location needs to be secured). Extended is a simple, yet scalable, routing scheme GPSR(greedy perimeter stateless routing) to select randomly a next-hop node with a certain probability for randomizing paths and to perform perimeter routing for detouring dormant sources so that the privacy strength of the active source, defined as safety period, keeps enhanced. The simulation results obtained by increasing the number of dormant sources up to 1.0% of the total number of nodes show that GSLP yields increased and nearly invariant safety periods, while those of PR-SP(Phantom Routing, Single Path), a notable existing protocol for source-location privacy, rapidly drop off as the number of dormant sources increases. It turns out that delivery latencies of GSLP are roughly less than two-fold of the shortest path length between the active source and the destination.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.189-196
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• 2009

We propose a hybrid broadcast scheduling based on a combination of periodic and on-demand data scheduling methods for mobile data broadcasting in convergence networks from communication and broadcasting. We consider an environment in which the forward channel is for data broadcasting and the reverse channel is for sending data requests via cellular phones, WLAN, WiBro, etc. Collecting statistics of requests from clients, the server partitions the data items into hot-item and cold-item sets. Hot items are sent based on a push-based scheduling. An on-demand scheduling method is applied to cold items. Performance evaluation from simulations shows that our proposed scheduling algorithm yields small response time with high successful response ratio.

• Convergence Security Journal
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• v.8 no.1
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• pp.79-90
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• 2008

Services over SIP protocol are anticipated to be commonly used services in our usual life. Especially, presence is a new feature in SIP-based services and actually entities' presence information has close relationship with privacy of them. Also, the XCAP-based authorization is accepted as a highly probable method to protect privacy of entities in SIP-based services. However, there is no proposed presence service model except IM service and it's hard to find the reference model that shows a way how we can apply XCAP-based authorization method into presence service. In this paper, we proposed new presence service model which is applicable to the VoIP service. We suggested presence service model which is making use of XCAP-based authorization to get protection of privacy in a organized way and the suggested model's each messaging steps were reviewed using concrete examples. Contributions of this work is in the suggestion of privacy-aware presence service using XCAP-based authorization and its verification of its each messaging step.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.349-357
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• 2017

Many Web sites adopt SMS(Short Message Service)-based user authentication when a user loses her password or approves an online payment. In SMS-based authentication, the authentication server sends a text in plaintext to a user's phone, and it allows an attacker who eavesdrops or intercepts the text to impersonate a valid user(victim). We propose a challenge-response scheme to prove to the authentication server that a user is in a certain place at the moment with her smartphone beside her. The proposed scheme generates a response using a challenge by the server, user's current location, and a secret on the user's smartphone all together. Consequently, the scheme is much more secure than SMS-based authentication that simply asks a user to send the same text arrived on her phone back to the server. In addition to entering the response, which substitutes the SMS text, the scheme also requests a user to input a passphrase to get the authentication process started. We believe, however, the additional typing should be tolerable to most users considering the enhanced security level of the scheme.

• The Journal of the Korea Contents Association
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• v.10 no.2
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• pp.120-129
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• 2010

MANET(Mobile Ad Hoc NETwork) is a collection of mobile nodes that are free to move and organize themselves in an arbitrary manner without any fixed infrastructures. These mobile nodes are connected by wireless links and act as routers for all other nodes in the network. As a router each node in MANET consumes its batteries when forwarding a message, and the selection of the best path to minimize the total power needed to route packets is needed to maximize the lifetime of all nodes. In this paper, we propose a routing protocol considering the remaining battery capacity of nodes in the routing paths. The proposed scheme prevents the battery of each node from being overused and increases the lifetime of the network.

• Journal of IKEEE
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• v.22 no.3
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• pp.590-598
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• 2018

Recently, interest in IoT(Internet of Things) technology, which provides Internet services to objects, is increasing. IoT offers a variety of services in home networks, healthcare, and disaster alerts. IoT with LLN(Low Power & Lossy Networks) feature frequently loses sensor node. RPL, the standard routing protocol of IoT, performs global repair when data loss occurs in a sensor node. However, frequent loss of sensor nodes due to lower sensor nodes causes network performance degradation due to frequent full path reset. In this paper, we propose an additional selection method of the storage mode sensor node to solve the network degradation problem due to the frequent path resetting problem even after selecting the storage mode sensor node, and propose a method of equalizing the total path resetting number of each instance.

• Journal of the Korea Society of Computer and Information
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• v.15 no.4
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• pp.91-98
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• 2010

Advances in communications and control technology, the strengthening of the Internet, and the growing recognition of the urgency to reduce the risk and production cost are motivating the development of improvements in the traditional manufacturing industry. In this paper, we developed a remote dust collector bag control system which is a combination of advanced IT and traditional dust collector based on the event. At first, we made the A/D(Analog/Digital) converter using a micro processor because the differential pressure transmission, which is a sensor of the dust collector, produces analog volt data. A/D converter can provide RS-232 communication to connect with Power Line Communication(PLC) modem. And, n-bytes message format was defined for the efficient dust collector bag information transmission from a dust collector to a user. Also, we designed the data types to model the dust collector and the dust collector bag, and they were logically modeled using XML and object-oriented modeling method. In addition to that, we implemented the system for showing the dust collector bag exchange time exactly to users at real-time using various visual user interfaces.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.61-68
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• 2011

Recently arithmetic circuit of lightweight AES symmetric key algorithm that can apply to passive tag have been developed, then security protocol of RFID system using AES symmetric encryption techniques have been proposed. This paper proposed security enhancement protocol of RFID system using lightweight AES arithmetic circuit and random number generator of passive tag. The proposed protocol have AES algorithm and random number generator at server, reader, tag, and transmit encrypted message by separate secret key using random number at each session. The mutual authentication of tag and reader used reader random number and tag random number. As a result, proposal protocol reduce authentication steps of the existing mutual authentication protocol, and reduce amount of computation of tag, and demonstrate as secure protocol to every attack type of attacker by decrease communication step of Air Zone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.274-281
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• 2006

Sensor network applications need synchronized time extremely such as object tracking, consistent state updates, duplicate detection, and temporal order delivery. This paper describes reliable time synchronization protocol (RTSP) for wireless sensor networks. In the proposed method, synchronization error is decreased by creating hierarchical tree with lower depth and reliability is improved by maintaining and updating information of candidate parent nodes. The RTSP reduces recovery time and communication overheads comparing to TPSN when there are topology changes owing to moving of nodes, running out of energy and physical crashes. Simulation results show that RTSP has about 20% better performance than TPSN in synchronization accuracy. And the number of message in the RTSP is $20%{\sim}60%$ lower than that in the TPSN when nodes are failed in the network. In case of different transmission range of nodes, the communication overhead in the RTSP is reduced up to 40% than that in the TPSN at the maximum.