• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.1
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• pp.7-12
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• 2010

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide an efficient utilization in optical Wireless networks. Under several legacy schemes, a switch drops the burst with a shorter time among ones regardless of its traversed hop counts. As a result, the dropped burst that have been traversed more hops might cause to waste bandwidth than the one traversed a few hops. Noting that this problem, we propose the Just Enough Time (JET) with a hop count scheme which can reduce the wasted bandwidth by prioritizing the burst traversed more hops over others. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the burst blocking probability and the link utilization.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.277-278
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• 2008

Localization system is an important problem for Wireless Sensor Networks(WSN). Since the sensor nodes are limited, the range-based that uses the special device for localization is unsuitable in WSN. DV-Hop is one of the range-free localization algorithm using hop-distance and number of hop count. But Its disadvantage is that it spend large communication cost in scalable sensor nodes. We propose a simple algorithm to reduce the communication cost, using the smallest number of hop count.

• Journal of Information Processing Systems
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• v.16 no.5
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• pp.1158-1168
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• 2020

The distance vector-hop wireless sensor node location method is one of typical range-free location methods. In distance vector-hop location method, if a wireless node A can directly communicate with wireless sensor network nodes B and C at its communication range, the hop count from wireless sensor nodes A to B is considered to be the same as that form wireless sensor nodes A to C. However, the real distance between wireless sensor nodes A and B may be dissimilar to that between wireless sensor nodes A and C. Therefore, there may be a discrepancy between the real distance and the estimated hop count distance, and this will affect wireless sensor node location error of distance vector-hop method. To overcome this problem, it proposes a wireless sensor network node location method by modifying the method of distance estimation in the distance vector-hop method. Firstly, we set three different communication powers for each node. Different hop counts correspond to different communication powers; and so this makes the corresponding relationship between the real distance and hop count more accurate, and also reduces the distance error between the real and estimated distance in wireless sensor network. Secondly, distance difference between the estimated distance between wireless sensor network anchor nodes and their corresponding real distance is computed. The average value of distance errors that is computed in the second step is used to modify the estimated distance from the wireless sensor network anchor node to the unknown sensor node. The improved node location method has smaller node location error than the distance vector-hop algorithm and other improved location methods, which is proved by simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2245-2266
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• 2016

The hop count routing metric is widely used in routing protocols of Wireless Sensor Networks (WSNs) due to its simplicity and effectiveness. With a lower hop count route, fewer transmissions are required to send a packet from the source to the destination. This can improve the throughput of a network because fewer transmissions results in less channel contention and interference. Despite this, the hop count routing metric may not be ideal for mobile scenarios where the topology of a network changes constantly and rapidly. In this paper, we propose to increase route stability in mobile WSNs by discovering paths that are more stable during route discoveries using routing metrics. Two routing metrics were proposed, the true beauty of these routing metrics lies in the fact that they can even be used even without specialized hardware such as GPS and other sensors. We implemented the proposed routing metrics in the AODV routing protocol and found that they are highly effective and outperform other stability-based routing metrics and the hop count routing metric.

• The Journal of the Korea Contents Association
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• v.8 no.7
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• pp.43-52
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• 2008

The AODV routing algorithm in a mobile ad-hoc networks broadcasts RREQ packet to find a route from a source to a destination. An attacker node may intercept a RREQ packet and attack by falsifying a field in that packet. In this paper, we propose a simply modified method which can protect a routing table from an attack to falsify the hop count field in the RREQ packet. When establishing a connection between a source and a destination, we update routing table of each node on the connection based on minimum delay instead of minimum hop count. By doing this, we can protect routing table from an attack to falsify a hop count Our simulation is implemented in Network Simulator(NS-2). We analyze how an attacker affects the mobile ad-hoc networks. The result of the simulation shows that the proposed mechanism transfers a data securely.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.97-103
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• 2009

Improving TCP performance has long been the focus of many research efforts in 802.11 wireless networks study. Hop count and Round Trip Time (RTT) are the critical sources which serious affect the TCP performance on end to end connection. In this paper, we analytical derived the affection and based on the analysis we propose TCP should Change its Expected Value (TCP-CEV) when hop count and RTT change by setting a reasonable CWND change rate to improve the performance. The proposed scheme is applicable to a wide range of transport protocols using the basic TCP mechanism, and the protocol behavior is analytically tractable. We show that our simple strategy improves TCP performance at least over 12% in a chain topology, 4.9% in a grid topology and improve the TCP convergence.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.322-324
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• 2004

서비스 거부 공격(Denial of Service)은 최근 가장 큰 관심의 대상이 되고 있는 공격 형태로 시스템이나 네트워크의 자원을 고갈시킴으로써 더 이상의 서비스를 제공하지 못하도록 하는 공격이다. 이러한 서비스거부 공격은 IP 스푸핑(spoofing) 기법을 사용하기 때문에 공격지의 근원지를 파악하기 어렵고, 필터링 기법을 사용하여 공격을 차단하기도 어렵다. 이러한 공격을 탐지하기 위해서 Hop Count Filtering 기법이 제안되어 있지만. 피해자에게 유입되는 각각의 패킷을 분석하여 스푸핑을 탐지하기에는 않은 지연과 과부하(Overhead)의 문제점이 있다. 이 것을 해결하기 위해서 본 논문에서는 PI (Path Identification Mechanism) 기법을 적용시켜, 스푸핑 된 패킷을 이용한 서비스 공격을 차단할 수 있는 구현방안을 제안하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.413-414
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• 2015

SDN은 네트워크 장비의 control plane과 data plane을 분리하고, 중앙의 컨트롤러를 통해 네트워크를 제어한다. 네트워크 운영에서 monitoring은 필수적인 요소이며, SDN 환경에서의 기존의 monitoring 방법인 OpenTM은 in-band network 환경을 고려하지 않았다. 본 논문은 in-band network 환경에서 hop-count와 정확도를 고려하여 높은 정확도를 유지하면서도 네트워크 부하를 줄일 수 monitoring 방법을 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.758-760
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• 2012

The wireless sensor network is used to get information that location tracing or data of surrounding areas. Unnecessary retransmission request or many energy consumption because the transmission over the wireless links. In order to select the link of reliable and energy efficient to estimate the quality of radio link technique is required using RSSI, LQI, and so on. In this paper, each path between the sensor nodes, a small in the path within standard deviation of shall be determined the priority. Each path a high priority of the node values, respectively LQI is accumulated. Node can be selected the high LQI value path. Among them the less hop count to select the path is proposed. The proposed algorithm is removed the paths of shorten life using high the LQI value of the entire and high hop count even less variation. So its advantage that the sensor nodes can be selected more reliable path.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.3
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• pp.37-42
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• 2007

This paper reconsiders established power conservation models for ubiquitous sensor networks that use relay nodes instead of direct communication and proposes novel network power consumption model with consideration of the channel level and radio chip level simultaneously. We estimate the effect of minimum hop-count policy in terms of network power consumption through simulation of various situations for low power RF module CC2420. It is observed that maximum RF power and minimum hop-count results in lower energy consumption relatively. Also, in total network energy consumption, which is included re-transmission, minimum hop count policy presents decrease by 33.1% of energy consumption in compare with the conventional model.