• Convergence Security Journal
• /
• v.21 no.1
• /
• pp.129-135
• /
• 2021

Greedy protocols show good performance in Vehicular Ad-hoc Networks (VANETs) environment in general. But they make longer routes causing by surroundings or turn out routing failures in some cases when there are many traffic signals which generate empty streets temporary, or there is no merge roads after a road divide into two roads. When a node selects the next node simply using the distance to the destination node, the longer route is made by traditional greedy protocols in some cases and sometimes the route ends up routing failure. Most of traditional greedy protocols just take into account the distance to the destination to select a next node. Each node needs to consider not only the distance to the destination node but also the direction to the destination while routing a packet because of geographical environment. The proposed routing scheme considers both of the distance and the direction for forwarding packets to make a stable route. And the protocol can configure as the surrounding environment. We evaluate the performance of the protocol using two mobility models and network simulations. Most of network performances are improved rather than in compared with traditional greedy protocols.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11a
• /
• pp.304-306
• /
• 2005

이동 애드혹 네트워크(Mobile Ad Hoc Network: MANET)는 유선 인프라 없이 구축된 무선 네트워크로 멀티 홉 통신을 수행할 수 있다. 인터넷 노드와 통신하고자 하는 MANET 노드에게 인터넷 연결을 가능하게 하는 방법이 요구되며 인터넷 연결은 인터넷과 MANET을 중계하는 인터넷 게이트웨이를 통해 지원된다. 게이트웨이들 간의 부하를 잘 분배한다면 네트워크 성능 향상을 얻을 수 있으므로, MANET 내에 여러 개의 인터넷 게이트웨이가 존재할 경우 이들 간의 부하균등화는 중요한 이슈이다. 본 연구에서는 부하균등화 기법을 제어 메시지의 플러딩 방법과 인터넷 게이트웨이를 선택하는 주체에 따라 4가지로 분류하며, 부하균등화 문제를 해결하기 위한 새로운 메트릭(metric)을 제안한다. 시뮬레이션을 통하여 홉 수와 라우팅 엔트리의 수를 메트릭으로 이용하는 새로운 기법의 성능이 기존 기법에 비하여 향상되었음을 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.580-581
• /
• 2018

In order to reduce end-to-end delay in EH-WSN (energy harvestin wireless sensor netowk), medium access control protocols using multi-hop routing technique have been studied. In a real environment, there are many situations where it is difficult to harvest enough energy than the energy consumed. Therefore, it is required to design a MAC protocol that allows nodes to reliably relay data without exhausting power in multi-hop transmission. In this paper, we propose a power-efficient MAC protocol that can select the relay node according to the residual power and the energy collection rate to increase network lifetime.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.3
• /
• pp.31-39
• /
• 2012

In this paper, we propose an energy-aware source routing protocol for maximizing a network lifetime in mobile ad hoc network environments. The proposed routing protocol is based on the source routing and chooses a path that maximize the path lifetime, by considering both transmit/receive power consumption and residual battery power in the mobile nodes from the perspective of source-destination end-to-end. This paper proposes a new routing cost and designs a new routing protocol for minimizing the control packet overhead occurred during the route discovery. Simulation results show that the proposed scheme has similar performances to the conventional routing schemes in terms of the number of transmission hops, transmission rate and total energy consumption, but achieves the performance improvement of 20 percent with respect to the lifetime.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.1
• /
• pp.441-448
• /
• 2014

USN(Ubiquitous Sensor Network) application software has a characteristic that it controls a variety of sensor nodes based on the various target operating systems. Accordingly, many researches for efficient development of USN application software are being performed. In this paper, the attributes design technique to support attribute-based development of USN node software for multi-platform is proposed. In the proposed technique, the method to design attributes for modeling Platform Independent Model and Platform Specific Model is presented. When using the proposed technique, productivity of software development will be increased because node software design for multi-platform is easily performed by selecting values of attributes. Also, maintainability of software will be increased because node software is easily regenerated by changing attributes according to the changes of operating systems.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.9
• /
• pp.33-38
• /
• 2014

The FCM based hybrid RBF network is a heterogeneous learning network model that applies FCM algorithm between input and middle layer and applies Max_Min algorithm between middle layer and output. The Max-Min neural network uses winner nodes of the middle layer as input but shows inefficient learning in performance when the input vector consists of too many patterns. To overcome this problem, we propose a dynamic learning rate control based on fuzzy logic. The proposed method first classifies accurate/inaccurate class with respect to the difference between target value and output value with threshold and then fuzzy membership function and fuzzy decision logic is designed to control the learning rate dynamically. We apply this proposed RBF network to the character recognition problem and the efficacy of the proposed method is verified in the experiment.

• Journal of Broadcast Engineering
• /
• v.15 no.3
• /
• pp.346-354
• /
• 2010

T-DMB is using MPEG-4 BIFS standard format for broadcasting interactive data service. BIFS enables us to represent contents as a scene which consists of various objects such as AV, image, graphic, and text. It also enables us to control objects by using user interaction. BIFS was designed to be adapted to multimedia systems with various input devices. Today, however, we are in lack of considering about mobile device with restricted input unit. The problem is that a consistent user control of interactive data contents is not possible due to the limitations of input units in T-DMB terminals. To solve the problem, we defined KeyNavigator node that provides a means to select or navigate objects (like menu) in BIFS contents by arrow keys and enter key of mobile terminal. By using KeyNavigater node, not only BIFS contents providers can make BIFS contents as they want, but also users can get a way to control BIFS contents consistently and easily.

• Journal of KIISE:Software and Applications
• /
• v.31 no.5
• /
• pp.537-542
• /
• 2004

Multi-Layer Perceptron network has been mainly applied to many practical problems because of its nonlinear mapping ability. However the generalization ability of MLP networks may be affected by the number of hidden nodes, the initial values of weights and the training errors. These factors, if improperly chosen, may result in poor generalization ability of MLP networks. It is important to identify these factors and their interaction in order to control effectively the generalization ability of MLP networks. In this paper, we have empirically identified the factors that affect the generalization ability of MLP networks, and compared their relative effects on the generalization performance for the conventional and visualized weight selecting methods using the controller box.

• Journal of Korea Society of Industrial Information Systems
• /
• v.27 no.6
• /
• pp.41-49
• /
• 2022

The Internet Engineering Task Force (IETF) has standardized RPL (IPv6 Routing Protocol for Low-power Lossy Network) as a routing protocol for Low Power and Lossy Networks (LLNs), a low power loss network environment. RPL creates a route through an Objective Function (OF) suitable for the service required by LLNs and builds a Destination Oriented Directed Acyclic Graph (DODAG). Existing studies check the residual energy of each node and select a parent with the highest residual energy to build a DODAG, but the energy exhaustion of the parent can not avoid the network disconnection of the children nodes. Therefore, this paper proposes EC-RPL (Enhanced Connectivity-RPL), in which ta node leaves DODAG in advance when the remaining energy of the node falls below the specified energy threshold. The proposed protocol is implemented in Contiki, an open-source IoT operating system, and its performance is evaluated in Cooja simulator, and the number of control messages is compared using Foren6. Experimental results show that EC-RPL has 6.9% lower latency and 5.8% fewer control messages than the existing RPL, and the packet delivery rate is 1.7% higher.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.3
• /
• pp.247-254
• /
• 2014

For wireless multimedia sensor network (WMSN), it is crucial to select appropriate channels to deliver multimedia data stream generated by image and voice sensors periodically or continuously. Although most of previous researches assume that fixed channels are used for wireless sensor networks, they causes limit to support various application areas. In this paper, we apply link-setup algorithms developed for wireless cognitive radio networks for searching common channels between two nodes without common control channels. We also show the algorithm causes serious performance degradation as the total number of used channels increases, and then propose a new link-setup algorithm to resolve the problem. Therefore, the proposed algorithm shows 30 % higher performance compared to existing algorithms.