• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.1929-1950
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• 2020

Reliable and secure data transmission in the application environment assisted by the wireless sensor network is one of the major challenges. Problem like blind forwarding and data inaccessibility affect the efficiency of overall infrastructure performance. This paper proposes routing protocol for forwarding and error recovery during packet loss. The same is achieved by energy and hops distance-based formulation of the routing mechanism. The reachability of the intermediate node to the source node is the major factor that helps in improving the lifetime of the network. On the other hand, intelligent hop selection increases the reliability over continuous data transmission. The number of hop count is factor of hop weight and available energy of the node. The comparison over the previous state of the art using QualNet-7.4 network simulator shows the effectiveness of proposed work in terms of overall energy conservation of network and reliable data delivery. The simulation results also show the elimination of blind forwarding and data inaccessibility.

• Journal of Communications and Networks
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• 제17권4호
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• pp.370-383
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• 2015

Effective link quality estimation is a vital issue for reliable routing in wireless networks. This paper studies the performance of expected transmission count (ETX) under different traffic loads. Although ETX shows good performance under light load, its performance gets significantly worse when the traffic load is high. A broadcast packet storm due to new route discoveries severely affects the link ETX values under high traffic load, which makes it difficult to find a good path. This paper presents the design and implementation of a variation of ETX called high load - ETX (HETX), which reduces the impact of route request broadcast packets to link metric values under high load. We also propose a reliable routing protocol using link quality metrics, which is called link quality distance vector (LQDV). We conducted the evaluation of the performance of three metrics - HETX, ETX and minimum hop-count. The simulation results show that HETX improves the average route throughput by up to 25% over ETX under high traffic load. Minimum hop-count has poor performance compared with both HETX and ETX at all of the different traffic loads. Under light load, HETX and ETX show the same performance.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.578-580
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• 2009

무선 센서 네트워크는 다양한 분야에 응용하여 사용하고 있다. 배터리를 사용하는 센서노드는 전원이 제한적이기 때문에 다양한 기능과 전송의 신뢰성보다 저전력을 사용하는 동작에 더 최적화 되어있다. 하지만 더욱 다양한 목적으로 정확한 데이터를 사용하기 위해서는 전송의 신뢰성이 보장되어야 한다. 멀티홉 환경으로 구성되어 있는 센서 네트워크에서 종단간 전송 신뢰성을 보장하기 위해서는 링크(홉)간의 전송 신뢰성이 바탕이 되어야 하지만, IEEE 802.15.4 표준은 링크계층의 전송 신뢰성을 고려하지 않고 있다. 본 논문에서는 에너지를 효율적으로 사용하면서 링크(홉)간 전송 신뢰성을 제공하기 위한 링크계층 프로토콜을 제안한다.

• 한국정보과학회논문지:정보통신
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• 제30권4호
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• pp.513-519
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• 2003

멀티캐스트 트래픽의 효율적 전달을 위해서는 멀티캐스트 라우팅과 신뢰성 있는 전송 방식이 요구된다. 신뢰성 있는 전송은 손실 패킷에 대한 재전송을 필요로 하며, 이를 위해 전송된 패킷은 재전송 버퍼에 저장되어 있어야만 한다. 따라서 재전송 버퍼의 관리 문제가 중요하며, 본 논문에서는 재전송 버퍼에 얼마나 많은 패킷을 저장할 것인가 하는 문제를 다룬다. 본 논문에서 제안하는 방식인 TBM(Timer based Buffer Management)은 멀티캐스트 트리 상의 응답자와 수신자들 사이의 NAK를 이용해서 얻어진 타이머 값을 기준으로 적정량의 버퍼를 유지하며, 동적인 네트워크 상황에 적응한다. 실험을 통해 TBM이 오류 상황이나 네트워크의 크기 등에 상관없이 버퍼를 능동적으로 관리하는 것을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권7호
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• pp.3386-3411
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• 2019

Secured and reliable routing is a crucial factor for improving the performance of Wireless Mesh Networks (WMN) since these networks are susceptible to many types of attacks. The existing assumption about the internal nodes in wireless mesh networks is that they cooperate well during the forwarding of packets all the time. However, it is not always true due to the presence of malicious and mistrustful nodes. Hence, it is essential to establish a secure, reliable and stable route between a source node and a destination node in WMN. In this paper, a trust based secure routing algorithm is proposed for enhancing security and reliability of WMN, which contains cross layer and subject logic based reliable reputation scheme with security tag model for providing effective secured routing. This model uses only the trusted nodes with the forwarding reliability of data transmission and it isolates the malicious nodes from the providing path. Moreover, every node in this model is assigned with a security tag that is used for efficient authentication. Thus, by combining authentication, trust and subject logic, the proposed approach is capable of choosing the trusted nodes effectively to participate in forwarding the packets of trustful peer nodes successfully. The simulation results obtained from this work show that the proposed routing protocol provides optimal network performance in terms of security and packet delivery ratio.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1801-1804
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• 1991

Described is a new type of control signal transmission system in which an optical fiber is used in place of metal wire cables. This optical transmission system is reliable against EMI and also eliminates the frequency band limitation on the metal wire cables. Since the Z80 CPU is used to distribute the instructions, many tasks can be carried out very easily, and many errors can be avoided. Although an experiment was carried out for 4 bit binary data, the number of bits can be increased to 6 or more without any degradation in reliability. Thus, a variety of applications can be expected to be actualized with this control signal transmission system.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.77-80
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• 2005

Wireless sensor networks(WSN) technology has various applications such as surveillance and information gathering in the uncontrollable area of human. One of major issues in WSN is the research for reducing the energy consumption and reliability of data. A system with forward error correction(FEC) can provide an objective reliability while using less transmission power than a system without FEC. In this paper, we propose to use LDPC codes of various code rate(0.53, 0.81, 0.91) for FEC for WSN. Also, we considered node-to-node interference in addition to AWGN channel. The proposed system has not only high reliable data transmission at low SNR, but also reduced transmission power usage.

• 대한전기학회논문지:전력기술부문A
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• 제54권2호
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• pp.73-78
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• 2005

The management of technological systems will become increasingly complex. Safe and reliable software operation is a significant requirement for many types of system. So, with software fault tolerance, we want to prevent failures by tolerating faults whose occurrences are known when errors are detected. This paper presents a fault location algorithm for single-phase-to-ground faults on the teed circuit of a parallel transmission line using software fault tolerance technique. To find the fault location of transmission line, we have to solve the 3rd order transmission line equation. A significant improvement in the identification of the fault location was accomplished using the N-Version Programming (NVP) design paradigm. The delivered new algorithm has been tested with the simulation data obtained from the versatile EMTP simulator.

• 대한전기학회논문지:전력기술부문A
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• 제51권9호
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• pp.460-466
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• 2002

A reliable fault phase selection algorithm plays a very important role in transmission line protection, Particularly in Extra High Voltage (EHV) networks. The conventional fault phase selection algorithm used the phase difference between positive and negative sequence current excluding load current. But, it is difficult to pick out only fault current since we can not know when a fault occurs and select the fault phase in weak-infeed conditions that dominate zero-sequence current in phase current. The proposed algorithm can select the accurately fault phase using the sum of unit vectors which are calculated by positive-sequence voltage and negative-sequence voltage.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.366-370
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• 2005

To meet increasing power demand, 500 kV power systems are under consideration in the regions of some Middle Asian countries. As the power system voltage becomes higher, the cost for the power system insulation increases significantly. 500 kV transmission systems will become the basis of a region's power system and they require much higher system reliability. Consequently, by the methods of limiting overvoltages effectively, a reasonable insulation design and coordination must be accomplished. In particular, the Substations must be constructed to be of outdoor type. In order to determine the various factors for the insulation design, the EMTP (Electro-magnetic transient program) is used for the magnification of transient phenomena of the 500 kV systems in the planned network. In this paper, we will explain the calculation results of lightning overvoltages by the EMTP for lightning protection design for the 500 kV substations. To obtain reliable results, the multi-story tower model and EMTP/TACS model are introduced for the simulation of dynamic arc characteristics.