• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.927-930
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• 2012

The sensor network technology for core technology of ubiquitous computing is in the spotlight recently, the research on ubiquitous sensor network is proceeding actively which is composed many different sensor node. One of the important condition for design of sensor node is to extend for network life which is to minimize power-consumption under the limited resources of sensor network. This study suggest routing protocol that was used second level cluster structure to reduce power-consumption of sensor node. the first level use the previous routing protocol under the LEACH, second level decide to transmit or not by comparision of data value for Effective Usage, reduce the unnecessary power-consumption.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.195-200
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• 2009

무선 센서 네트워크에서의 통신은 여러 계층으로 나뉘어 각 계층별 역할을 수행하므로 무선통신이 가능할 수 있다. 센서 네트워크에서의 통신계층 중 하나인 MAC(Medium Access Control)계층은 데이터의 에러, 흐름을 제어하고 자원을 관리하기 위해서 사용되며 MAC Protocol을 사용하여 센서 노드간의 통신을 보장한다. 전통적인 MAC Protocol은 패킷 처리율의 최대화, 지연의 최소화 및 공평성 제공이 주된 목적으로 설계된 된다. 무선 센서 네트워크에서 MAC 프로토콜은 응용에 따라 차이는 있으나 대부분 많은 센서 노드들로 구성된다. 또한 멀티 홉 통신을 하기 때문에 센서 장치의 제한된 배터리 수명으로 인해 소모되는 에너지를 최소화 하여 네트워크 에너지의 효율성을 높이는 것이 가장 큰 목적이다. 본 논문에서는 에너지 효율성 측면을 강조하기 위해서 MAC프로토콜의 문제점을 알아보고 그 중에서 최우선적으로 요구되는 에너지 효율성에 대해서 S-MAC, T-MAC의 비교와 T-MAC의 확률값을 변경에 따른 어느 경우가 가장 효율적인지 active time을 통하여 알아보았다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.542-558
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• 2016

Vehicular Ad Hoc Networks (VANETs) are self-configuring networks where the nodes are vehicles equipped with wireless communication technologies. In such networks, limitation of signal coverage and fast topology changes impose difficulties to the proper functioning of the routing protocols. Traditional Mobile Ad Hoc Networks (MANET) routing protocols lose their performance, when communicating between vehicles, compromising information exchange. Obviously, most applications critically rely on routing protocols. Thus, in this work, we propose a methodology for investigating the performance of well-established protocols for MANETs in the VANET arena and, at the same time, we introduce a routing protocol, called Genetic Network Protocol (G-NET). It is based in part on Dynamic Source Routing Protocol (DSR) and on the use of Genetic Algorithms (GAs) for maintenance and route optimization. As G-NET update routes periodically, this work investigates its performance compared to DSR and Ad Hoc on demand Distance Vector (AODV). For more realistic simulation of vehicle movement in urban environments, an analysis was performed by using the VanetMobiSim mobility generator and the Network Simulator (NS-3). Experiments were conducted with different number of vehicles and the results show that, despite the increased routing overhead with respect to DSR, G-NET is better than AODV and provides comparable data delivery rate to the other protocols in the analyzed scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1744-1754
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• 1998

In this paper, the data service protocol which could support data service more efficiently between mobile host and fixed host in wire network is investigated. Wireless link has high bit error rate compared with wire link. Therefore, TCP performance for the data service is degraded in wire and wireless interworking environment. Thus, to reduce performance degradation. Interworking module withsimple protocol processing function is proposed. This, interworking module analyzes the hearder information of TCP fram. If received TCP freame is a duplicated frame, TCP frame is discared. Also, if interworking moudule receives retransmission request frame is a duplicated frame, TCP freme is discarded. Also, if interworking module receives retansmission request frame, interworking module performs retransmission procedure. According to simulation results, the proposed IWF shows better performance than traditional IWF in view of delay and throughput in the wire and wireless interworking environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.973-986
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• 1999

In this paper, we propose MAC protocol that consists of channel access mechanism and transmission mechanism to support effective wireless packet data service. In channel access mechanism, broadcast channel announces status information of random access channel, and mobile station tries random access based on status information. Also, mobile station has access probability to prevent collision increase due to transmission of short message. For effective transmission, mobile station changes transmission rate based on transmission queue status to adapt burst traffic characteristics. In restricted environments of transmission code and bandwidth, proposed protocol shows better performance than cdma2000 system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.876-884
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• 2008

In this paper, we propose an asynchronous MAC protocol to minimize energy usage and to maximize data throughput for a wireless sensor network in multi channel environments. Our proposed SPMC-MAC (Slim Preamble Multi-Channel Media Access Control) adopts the preamble sliming mechanism proposed in [6] that takes advantage of the knowledge about the wakeup time of the receiver node. The preamble contains the receiver's ID and a randomly selected channel ID for data communication, and it is transmitted over a dedicated common channel. The power control has the benefit of keeping an appropriate number of nodes with the communication range, resulting in reduced collision and interference. We compare our SPMC-MAC and X-MAC extensively in terms of energy consumption and throughput using mathematical analysis and simulation.

• Steel and Composite Structures
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• v.1 no.1
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• pp.145-158
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• 2001

An experimental study was conducted to evaluate the effects of loading sequence and lateral bracing on the behavior of reduced beam section (RBS) steel moment frame connections. Four full-scale moment connections were cyclically tested-two with a standard loading history and the other two with a near-fault loading history. All specimens reached at least 0.03 radian of plastic rotation without brittle fracture of the beam flange groove welds. Two specimens tested with the nearfault loading protocol reached at least 0.05 radian of plastic rotation, and both experienced smaller buckling amplitudes at comparable drift levels. Energy dissipation capacities were insensitive to the types of loading protocol used. Adding a lateral bracing near the RBS region produced a higher plastic rotation; the strength degradation and buckling amplitude were reduced. A non-linear finite element analysis of a one-and-a-half-bay beam-column subassembly was also conducted to study the system restraint effect. The study showed that the axial restraint of the beam could significantly reduce the strength degradation and buckling amplitude at higher deformation levels.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.2
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• pp.83-91
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• 2018

With the development of IT (Information Technology) technology, embedded system and network technology are combined and used in various environments such as military environment as well as everyday life. In this paper, we propose a new airdropped distributed mobility model (ADMM) modeling the dispersion falling of the direct shot of a cluster bomb, and we compare and analyze some representative MANET routing protocols in ADMM in ns-3 simulator. As a result of the analysis, we show OLSR routing protocol is promising in ADMM environment in the view points of packet delivery ratio (PDR), end to end delay, and jitter. In addition, we propose a new adaptation scheme for OLSR, AND-OLSR (Average Node Distance based adaptive-OLSR) to improve the original OLSR in ADMM environment. The new protocol calculates the average node distance, adapts the period of the control message based on the average node distance increasing rate. Through the simulation study, we show that the proposed AND-OLSR outperforms the original OLSR in PDR and control message overhead.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.1
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• pp.51-58
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• 2015

Internet of Thing is a collection of various technical components, and the interworking among heterogeneous devices, networks, applications is expected to be accelerated through the openness of IoT platform. For this reason, many technical and administrative security threats will occur in IoT environments. In this paper, authentication methods of recent researches are analyzed for safe IoT services, and new mutual authentication protocol is proposed to provide more secure communication. The proposed protocol prevents an impersonation as malicious gateway or illegal device providing mutual authentication between gateway and IoT device. The performance analysis and evaluation of proposed authentication protocol are performed.

• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.267-274
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• 2006

The process of binding update for the routing optimization in MIPv6 can make the involved MN (Mobile Node) and CN(Correspondent Node) vulnerable to various attacks. Therefore, securing binding update process becomes an important research issue in the MIPv6, and several secure binding update protocols have been proposed. In this paper, we compare several existing binding update protocols, and analyze the vulnerability of MNs and CNs to the possible attacks and the management overhead of the SUCV(Statistic Uniqueness and Cryptographic Verifiability) which is considered to be superior to other protocols. Then, we propose an advanced protocol to resolve above drawbacks. Through the detailed analysis, we show that our protocol can reduce the computational overhead of MN, enable better management, and achieve a higher level of security against the redirect attacks, DoS(Denial of Service) attacks and brute force attacks, compared to SUCV.