• The KIPS Transactions:PartC
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• v.12C no.7 s.103
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• pp.941-948
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• 2005

In the self-healing group key distribution scheme, users are capable of recovering lost group keys on their own without requesting additional transmission from the group manager, where there is no reliable network infrastructure. In this paper, we propose a new self-healing group key distribution scheme with revocation capability, which is optimal in terms of user memory storage and more efficient in terms of communication complexity than the previous results. We obtain a slightly improved result from (13) and (14) by using the new broadcasting method. In addition, we prove that our scheme has the properties of t-wise forward secrecy and t-wise backward secrecy, and extend this self-healing approach to the session key recovery scheme from a single broadcast message.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.377-386
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• 2008

In this paper, a new handover management scheme has been proposed to reduce handover latency and to support fast handover without packet losses, so that it may be applicable to the wireless mobile Internet system such as IPv6-based WiBro system. To minimize the handover latency in processing of movement detection, we propose the handover management scheme which simplifies the handover message exchanging procedure between mobile subscriber station (MSS) and network by integrating layer 2 and layer 3 handovers efficiently based on the layer2 information. To reduce the processing delay from new care-of-address (NCoA) configuration during handover, we propose that NCoA is created, distributed and managed by new access control router (NACR). In addition, in order to minimize the packet transmission delay and eliminate the packet losses, the proposed scheme employs a crossover router (CR) which is upper network located over PACR and NACR and employs the packet buffering for MSS. The simulation study shows that the proposed scheme achieves loss-free packet delivery and low latency in the environment of narrow overlapped cell area or high velocity of the MSS, comparing the performance with the conventional schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8A
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• pp.618-624
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• 2009

In the evolution from wireless sensor networks(WSNs) to ubiquitous sensor networks(USNs), technologies that can support intensive data-traffic loads, large number of users, improved interoperability, and extreme longevity are required. Therefore, efficient communication time coordination control and low power consumption becomes one of the most important design goals for USN MAC protocols. So far several time division multiplexed (TDM) MAC protocols have been proposed. However, since the pros and cons of existing protocols are not easy to analyze, it becomes a challenging task to design improved TOM MAC protocols. Based on this objective, this paper provides a novel protocol analysis along with a message complexity derivation and comparison of the existing TDM MAC protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1173-1181
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• 2007

A number of routing algorithms have been studied for wireless mobile ad-hoc network. Among them, the AODV routing algorithm with on-demand method periodically transmits hello message and monitors link state during data transmission in order to maintain routing paths. When a path is disconnected, a node that senses it transmits a RERR packet to the transmitting node or transmits a RREQ locally so that the path could be repaired. With that, the control packet such as a RREQ is broadcast, which causes the consumption of bandwidth and incurs data latency. This paper proposes a LRRLBP algorithm that locally repairs a path by predicting link state before disconnecting the path based on the AODV routing protocol for solving such problems. Intensive simulations with the results using NS-2 simulator are shown for verifying the proposed protocol.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.60-68
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• 2006

Using the wireless communication among unacquainted vehicles, an intelligent vehicle safety system can be constructed to exchange vehicle safety-related information, such as urgency stop, traffic accident and road obstacles. In the majority of vehicle safety applications, vehicle safety messages are propagated in the form of broadcast. However, this approach causes some effectiveness and performance problems with massive radio collision, multi-hop propagation. This paper presents a priority based relay node selection method for propagating vehicle safety messages of traffic accident protection system. With this method, vehicle safety messages are relayed by a node that locates in proper distance out of the nodes that are included in the radio transmission range. By decreasing the number of duplicated messages, the packet overhead is lessened while the communication performance is raised. The proposed method was proven to be better than other schemes through network simulations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.475-480
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• 2012

This study on the methode is easied to distinguish with emotional visual lighting on AtoN facility using 3colors LED, and which is controlled to on-off switching of approach light in shore or harbor. The identification have easied to provide a differentiation between the AtoN facility of red and white light and surrounding light in harbor both sides. And the integrated controller have designed to left-right and serial sequential lighting system for harbor guidance using the GPS synchronous or timer. There is expectation effect that is prevent a confusion about distinguish of facility by ship's operator and to beautify a night scene of harbor, which is expressed to emotional identification lighting and variable color lighting on AtoN body by vertical layer color lighting using LED. In addition, the performance of AtoN is implemented to display with guidance light the harbor safety message by morse code lighting. Effectiveness of system is enhanced that age and power consumption reduce by candle alternated high light LED.

• Journal of IKEEE
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• v.10 no.1 s.18
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• pp.55-61
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• 2006

In modern society, development of medical technology has extended the human life span. However, it has also caused some side-effects. Mostly old people who live alone are not available the medical service quickly when they are in emergency situations. Moreover heart related diseases as well are rapidly increasing with aging. This study proposes the emergency medical alarm system. This system measures the physiological signals such as ECG(electrocardiogram), temperature, and motion data, analyzes those data automatically, and sends the urgent message to the Emergency Medical Center and to their family. There are two main parts in the system. In the first part, physiological data acquisition part, the troublesome addition and deletion of body signals on existing proposed systems have been supplemented, which led to the modulized production by means of ECG sensor module, temperature sensor module, acceleration sensor module. The other part is mobile unit, which includes signal processing and transmission functions. And bluetooth allows two parts to communicate with each other. Data that are processed in the mobile unit are stored in the PC database through the WLAN using TCP/IP protocol.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.157-163
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• 2020

Recently, fine dust has been known to cause cardiovascular diseases here, raising interest in ways to reduce emissions by efficiently using fuel from cars that cause air pollution. Accordingly, a driving assistance system was developed to save fuel by eco-driving and improve the driver's bad driving habits. The system was developed using raspberry pi, arduino and Android. Using RPM, speed, fuel injection information obtained from OBD-II, and gyro-sensor values, Fuel-Cut is induced to create an optimal inertial driving environment. It also provides various information system such as weather, driving environment, and preventing drowsy driving through GUI and voice recognition functions. It is possible to check driving records and vehicle fault information using Android application and has low overhead for message transmission using MQTT protocol optimized for IoT environment.

• Convergence Security Journal
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• v.15 no.4
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• pp.35-41
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• 2015

Internet of Things has a wide range of vulnerabilities are exposed to information security threats. However, this does not deal with the basic solution, the vaccine does not secure encryption for the data transmission. The encryption and authentication message transmitted from one node to the construction of the secure wireless sensor networks is required. In order to satisfy the constraint, and security requirements of the sensor network, lightweight encryption and authentication technologies, the light key management technology for the sensor environment it is required. Mandatory sensor network security technology, privacy protection technology subchannel attack prevention, and technology. In order to establish a secure wireless sensor networks encrypt messages sent between the nodes and it is important to authenticate. Lightweight it shall apply the intrusion detection mechanism functions to securely detect the presence of the node on the network. From the sensor node is not involved will determine the authenticity of the terminal authentication technologies, there is a need for a system. Network security technology in an Internet environment objects is a technique for enhancing the security of communication channel between the devices and the sensor to be the center.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.38-46
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• 2010

A stable game managing system is absolutely needed to accept simultaneous interlacing of many users for on- line game system. The proposed P2P on-line game system in this paper is able to get stable and real-time game managing within limited time stamp utilizing through reorganizing peers according to synchronous time which can be avoid congestion on one region, it is possible to synchronize for game nodes within limited time stamp utilizing. Reorganizing M-tree which leads 10 distribute loads. The system manages each region unit, and it is execute no matter how big game sizes are. Thus to ensure such as the problems of expand server and stabilization or message transmission. Also, prove efficiency of the suggested system through the simulation.