Chonggun Kim

A Leader Election Algorithm Within Candidates on Ad Hoc Mobile Networks

Leader election is an extensively studied problem in Ad hoc networks. In our study, an extended idea of leader election algorithms for energy saving on arbitrary changing topological environment is derived. Our focus is to reduce the number of leader election processes, to make it more energy efficient. The proposed algorithm shows that each node maintains a list of candidates to minimize the total number of leader elections. Simulation results show that the leader election algorithm using candidates has less leader elections process and generates less message than those of the existing leader election algorithms.

A resource reuse method in cluster sensor networks in ad hoc networks

Sensor nodes having the limited resource, energy efficiency is an important issue. Clustering on the sensor networks reduces the volume of inter-node communications and raises energy efficiency by transmitting the data collected from members by a cluster head via a sink node. But, due to radio frequency characteristics, interference and collision can occur between neighbor clusters, the resulted re-transmission is more energy consuming. The previous problems occurred between neighbor clusters can be resolved by assigning channels which do not overlap between neighbor clusters. In this paper, we propose a method which assigns and reuses channels which do not overlap between neighbor clusters in dynamic cluster sensor networks. The resource allocation model of the proposed method is analyzed by correctness and simplicity.

Design of Knowledge Discovery Agent for a Bit-Map on Ad Hoc Mobile Networks

A main nature of ad hoc mobile networks is frequent change on their topology that is the source of many problems to be solved. AODV is an on-demand routing protocol for decreasing maintenance overhead on ad hoc networks. But some path breaks can cause significant overhead and transmission delays. If the maintenance overhead of routing table can be reduced, table-driven routing methods could be an efficient substitution. In this paper, we propose a knowledge discovery agent for an effective routing method that is using the simple bit-map topology information. The agent node gathers topology knowledge and creates topology bit-map information. All paths for source to destination can easily be calculated by the bit-map. All the other nodes on the network maintain the bit-map distributed from agent and uses it for routing. Correctness of the proposed agent method is verified by computer simulations.

The Research Trends and the Effectiveness of Smart Learning

The introduction of useful microblogging services like Twitter derives significant changes in various areas of society. The smart tools such as mobile devices and microblogging services have led to great changes in the traditional way of education. It is possible to access good quality educational contents and methods in a more convenient way. Although a lot of smart tools have been applied for educational application, there are only limited researches that demonstrate the educational effectiveness of smart tools through experiment considerations. In this study, research documents about smart learning from 2007 have been treated based on 5 major searching sites; we investigate the research trends of smart learning of education. The opinion of the researchers about the educational use of smart tools is analyzed. Then, through substantial experiment, we are acquainted that the smart tools have a positive effect on the educational environment. As a practical application, the Twitter microblogging service is used for educational communications in 2 classes of a university during a semester. As a result, we can find that smart tools contribute to increase the efficiency of education, but learners and teachers need to pay considerable efforts on the use of smart tools to achieve the purpose.

A Routing Agent Using Cross-Layer Method for Collision Avoidance in Ad Hoc Networks

The cross-layer design approach is an important concept in ad-hoc networks which is adopted to solve several open issues. It aims to overcome MANET performance problems by allowing protocols belonging to different layers to cooperate and share network status information while still maintaining separated layers. In this work, we provide a routing agent of cross layer method which is based on the cooperation between Adjacency matrix routing protocol and the IEEE 802.11e MAC protocol. This proposal aims to avoid the congested nodes and guarantee better performance in terms of delay, packet delivery ratio, and so on. In the proposed method, each node maintains an adjacency matrix representing the network topology and MAC conditions with neighbors. The number of retransmissions in MAC layer is introduced as an indication of congestion. When the congestion occurs, the source node works as the routing agent to detect new route by checking MAC information and the adjacency matrix to the destination. The simulation results show that Cross layer give better performance than network layer only methods, especially in the frequent congestion condition.

Analysis of Twitter research trends based on SLR

With the increasing interest in micro blogging services, extensive research has focused on Twitter for a variety of purposes. For effective research on Twitter, an investigation of academic research papers related with Twitter will be required in order to analyze research trends. However, it is not easy to review the vast data. Therefore, we extract the representative literature related to Twitter and investigate the trends in Twitter research by using the systematic literature review (SLR) method. The five most popular resource sites are selected to collect Twitter-related literature and the 106 papers selected based on SLR are analyzed to study interesting trends in Twitter research. To classify the research area, the selected papers are divided into five main research categories according to research topics. In addition, other valuable results such as the inclination of the authors are also understood.

Influence of Twitter Activity on College Classes

With the rapid adoption of smartphones, Twitter has become a major mobile SNS. In spite of the increasing use of Twitter services by students and instructors in colleges, very little empirical studies that concern the impact of social media on the student learning environment have been published. In this paper, a Twitter utilization experiment is conducted for college classes to understand the effects on college student engagement and grades. The participants of experimental study comprise students of 2 college classes during one semester and only voluntary students attend this Twitter-based experiment. Network of Twitter using pattern such as community building, collaboration relationship and information sharing among students are analyzed. Some results about the relationships of seat positions, following patterns and grades among students have been studied. Through understanding of the students netwoking pattern, we find that the possibility of Twitter as a mobile educational tool.

Dynamic Packet Balancing Agent in MANETs Based on AOMDV

A MANET comprises a set of mobile devices which are capable of communicating with others. Despite its flexibility and portability, it suffers from energy limitation. If the energy consumption of the nodes in the MANET cannot be balanced efficiently, some nodes will die in an early stage due to the energy depletion, which in turn partitions the whole network and leads to the communication failure. To balance the energy consumption, we propose the dynamic packet balancing agent for MANETs. The agent utilizes the HELLO packets to update energy information along a path, which enables the dynamic update of the energy information of each path, and sends packets via the path with the best energy condition. The agent is further applied to AOMDV, a well-known multipath protocol. Simulation result generated by NS2(Network Simulator version 2) shows that our proposal outperforms AOMDV in balancing energy consumption.

Avoidance of channel interference in polygonal IoT networks: Kim ET AL.

One of the popular methods studied for indoor positioning is based on Wi‐Fi signal strength. But distance decisions using signal strength show not only intuitive results but also irregular results. Some sensors are used to increase the correctness of indoor positioning. Compass sensors and laser sensors were proven to be good additional methods for better positioning in a Wi‐Fi–based system. The main role of Wi‐Fi access points (APs) in indoor positioning is making the preliminary decision using received signal strength indicator (RSSI) signals and providing the infrastructure for communications.

Leader election based on centrality and connectivity measurements in ad hoc networks

Decision making process for agent systems is an important issue in dynamic network environment. This study proposes a novel method for determining leader node by measuring centrality and connectivity in the networks. The proposed method shows that each node maintains a list of the agent candidate to minimize the load of agent reelection. The agent provides services for various operations of the network and controls problems of network in both wired and wireless systems. The proposed agent decision method uses the topological centrality of the network, the degree of connectivity, node energy states as election keys. Simulations and numeric analysis are shown to verify the effect of the proposed decision method.