• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.438-441
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• 2004

인터넷의 급속한 발전과 컴퓨터 성능의 발달로 많은 사용자들은 네트워크를 통해 정보를 획득하고 이용하고 있다. 이에 따라 사용자의 요구도 빠르게 증가하고 있으며, 이러한 사용자 요구를 해결하기 위해 액티브 네트워크와 같은 기술들이 활발하게 연구되고 있다. 액티브 네트워크란 라우터나 스위치가 프로그램 실행 능력을 가지고 있어서 프로그램을 포함하고 있거나 중간 노드의 프로그램을 실행하도록 하는 패킷을 다양하고 유동적으로 처리할 수 있는 환경을 말한다. 이러한 액티브 네트워크의 중간 노드(Active Node)는 단순한 패킷 전달(forwarding) 기능 이외에 사용자의 실행 코드를 저장하고, 처리할 수 있는 기능을 가지고 있다. 따라서 액티브 노드에서 패킷을 실행하기 위해서는 각 패킷을 처리하는데 필요한 실행 코드가 요구되고, 이러한 실행 코드는 이전의 액티브 노드나 코드 서버에 요청함으로써 얻을 수 있다. 하지만 이러한 실행 코드를 이전 액티브 노드나 코드 서버에서 가져오게 되면 실행코드가 전달될 때까지의 시간지연이 발생하므로 사용되었던 실행 코드를 액티브 노드의 캐시에 저장하여 코드의 실행 속도를 증가 시킬 필요가 있다. 따라서 본 논문에서는 액티브 노드 상에 실행 코드를 효율적으로 캐시 함으로써 실행코드 요청의 횟수를 줄이고 패킷 처리 속도를 향상시킬 수 있는 캐싱 기법을 제안하였다.

• Annual Conference of KIPS
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• 2013.11a
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• pp.400-401
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• 2013

Mobility in a network causes link disconnections and link recovery is vital for reliability of a network. A link failure affects all the preceding nodes on a damaged routing path; creates communication delay, throughput degradation, and congestion. This paper proposes link recovery mechanisms in CCN based networks. Packet overhearing is used to update neighboring nodes information. The recovery is done by forwarding node resulting in low control overhead, and better efficiency. The proposed mechanisms increase overall performance of a typical CCN and simulation results show that our proposed scheme works very well in densely populated networks with high mobility.

• Journal of information and communication convergence engineering
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• v.19 no.2
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• pp.67-72
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• 2021

Wireless sensor networks (WSNs) require an enormous number of sensor nodes (SNs) to maintain processing, sensing, and communication capabilities for monitoring targeted sensing regions. SNs are generally operated by batteries and have a significantly restricted energy consumption; therefore, it is necessary to discover optimization techniques to enhance network lifetime by saving energy. The principal focus is on reducing the energy consumption of packet sharing (transmission and receiving) and improving the network lifespan. To achieve this objective, this paper presents a novel improved energy-efficient cluster-based routing protocol (IECRP) that aims to accomplish this by decreasing the energy consumption in data forwarding and receiving using a clustering technique. Doing so, we successfully increase node energy and network lifetime. In order to confirm the improvement of our algorithm, a simulation is done using matlab, in which analysis and simulation results show that the performance of the proposed algorithm is better than that of two well-known recent benchmarks.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.113-121
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• 2007

Commonly, in the Sensor Network that composed with multiple nodes uses Ad-hoc protocol to communicate each other. Each sensed data packets are collected by base node and processed by Host PC. But the Ad-hoc protocol is too vulnerable to Sinkhole attack, where the intruder attracts surrounding nodes with unfaithful routing information, and then performs selective forwarding or changes the data passing through it. The Sinkhole attack increases overhead over the network and boosts energy consumption speed to decrease network's life time. Since the other attacks can be easily adopted through sinkhole attack, the countermeasure must be considered carefully. In this paper, we proposed the Hop-depth algorithm that detects intruder in Sinkhole attack and colluded nodes. First, the proposed algorithm makes list of suspected nodes and identifies the real intruder in the suspected node list through the Hop-depth count value. And recalculates colluder's path information to find the real intruder. We evaluated the performance of the proposed algorithm using NS2. We compared and analyzed the success ratio of finding real intruder, false positive ratio, false negative ratio, and energy consumption.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.244-254
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• 2006

This paper presents an efficient hybrid technique to compact the trie indexing the huge forward table small enough to be stored into cache for speeding up IP lookup. It combines two techniques, an encoding scheme called bit-map and a controlled-prefix expanding scheme to replace slow memory search with few fast-memory accesses and computations. For compaction, the bit-map represents each index and child pointer with one bit respectively. For example, when one node denotes n bits, the bit-map gives a high compression rate by consumes $2^{n-1}$ bits for $2^n$ index and child link pointers branched out of the node. The controlled-prefix expanding scheme determines the number of address bits represented by all root node of each trie's level. At this time, controlled-prefix scheme use a dynamic programming technique to get a smallest trie memory size with given number of trie's level. This paper proposes standard that can choose suitable trie structure depending on memory size of system and the required IP lookup speed presenting optimal memory size and the lookup speed according to trie level number.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.7
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• pp.495-499
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• 2009

An underlying assumption in geographic routing protocols, periodic position exchange among neighbors has two problems: (1) unnecessary energy consumptions of nodes in regions without data delivery and (2) position invalidation of neighbors in forwarding data. Hence, this paper proposes an on-demand geographic routing protocol in mobile wireless sensor networks. The proposed protocol make a sender acquire position information of only necessary neighbors to reduce energy consumption in data forwarding time and determine an optimal node among them as a receiver for relaying data to a destination by considering their mobility. Simulation results show that the proposed protocol is more efficient than an existing geographic routing protocol.

• KIISE Transactions on Computing Practices
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• v.23 no.5
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• pp.310-315
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• 2017

In a centralized control structure, the software defined network controller manages all openflow enabled switched in a data plane and controls the telecommunication between all hosts. In addition, the network manager can easily deploy the network function to the application layer with a software defined network controller. For this reason, many methods for network management using a software defined network concept have been proposed. The main policies for network management are related to traffic Quality of Service and resource management. In order to provide Quality of Service and load distribution for network users, we propose an efficient routing method using a naive bayesian algorithm and transmission delay estimation module. In this method, the forwarding path is decided by flow class and estimated transmission delay result in the software defined network controller. With this method, the load on the network node can be distributed to improve overall network performance. The network user also gets better dynamic Quality of Service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1328-1336
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• 2012

Compared to terrestrial RF communications, underwater acoustic communications have several limitations such as limited bandwidth, high level of fading effects, and a large underwater propagation delay. In this paper, in order to tackle those limitations of underwater communications and to make it possible to form a large underwater monitoring systems, we propose a hierarchical underwater network architecture, which consists of underwater sensors, clusterheads, underwater/surface sink nodes, autonomous underwater vehicles (AUVs). In the proposed architecture, for the maximization of packet delivery ratio and the minimization of underwater sensor's energy consumption, a hybrid routing protocol is used. More specifically, cluster members use Tree based routing to transmit sensing data to clusterheads. AUVs on optimal trajectory movements collect the aggregated data from clusterhead and finally forward the data to the sink node. Also, in order to minimize the maximum travel distance of AUVs, an Integer Linear Programming based algorithm is employed. Performance analysis through simulations shows that the proposed architecture can achieve a higher data delivery ratio and lower energy consumption than existing routing schemes such as gradient based routing and geographical forwarding. Start after striking space key 2 times.

• Journal of Internet Computing and Services
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• v.15 no.2
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• pp.9-18
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• 2014

The sensors attached on/in a person are moved since human body frequency changes their activity, therefore in wireless body area networks, nodal mobility and non-line-of-sight condition will impact on performance of networks such as energy efficiency and reliable communication. We then proposed schemes which study on forwarding decisions against frequent change of topology and channel conditions to increase reliable connections and improve energy efficiency. In this work, we control the size of packets, forwarding rate based on ratio of input links and output links at each node. We also robust the network topology by extending the peer to peer IEEE 802.15.4-based. The adaptive topology from chain-based to grid-based can optimal our schemes. The simulation shows that these approaches are not only extending network lifetime to 48.2 percent but also increase around 6.08 percent the packet delivery ratio. The "hot spots" problem is also resolved with this approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.1050-1061
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• 2009

The Tactical Internet(TI) managed by Infantry Brigades is used for the purpose of sharing information of Command Control and Situation Awareness. When there are more than two destinations to transmit data in the TI system, a multicasting is utilized based on pre-defined multicast groups. However even in the case when a source node needs to send some messages like weathercast and attack alarm etc to only a part of Battalion or Brigades in a specific geographical region (destination region), the current TI multicasting protocol is designed to transmit the messages to the pre-defined group or all of the Battalion/Brigade nodes, resulting in inefficiency in terms of end-to-end delay and overhead. In this paper, we propose more efficient protocol for such cases, named as "Tactical Internet Geocasting (TIG)". The proposed scheme firstly checks whether the destination region belongs to one Battalion region or more than two Battalion regions using location information, and then performs a greedy forwarding from the source node to the destination region, followed by a local flooding inside of the destination region. With performance analysis and simulations using NS-2, TIG is compared to the current TI multicasting protocol (i.e., Simplified MDP) and the LBM (Location-based Multicast). The simulation results show that the proposed TIG is more efficient than both in terms of delay and network overhead.