• International Journal of Computer Science & Network Security
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• v.23 no.4
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• pp.55-68
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• 2023

In recent years, the Television White Space (TVWS) has attracted the interest of many researchers due to its propagation characteristics obtainable between 470MHz and 790MHz spectrum bands. The plenty of unused channels in the TV spectrum allows the secondary users (SUs) to use the channels for broadband services especially in rural areas. However, when the number of SUs increases in the TVWS wireless network the aggregate interference also increases. Aggregate interferences are the combined harmful interferences that can include both co-channel and adjacent interferences. The aggregate interference on the side of Primary Users (PUs) has been extensively scrutinized. Therefore, resource allocation (power and spectrum) is crucial when designing the TVWS network to avoid interferences from Secondary Users (SUs) to PUs and among SUs themselves. This paper proposes a model to improve the resource allocation for reducing the aggregate interface among SUs for broadband services in rural areas. The proposed model uses joint power and spectrum hybrid Firefly algorithm (FA), Genetic algorithm (GA), and Particle Swarm Optimization algorithm (PSO) which is considered the Co-channel interference (CCI) and Adjacent Channel Interference (ACI). The algorithm is integrated with the admission control algorithm so that; there is a possibility to remove some of the SUs in the TVWS network whenever the SINR threshold for SUs and PU are not met. We considered the infeasible system whereby all SUs and PU may not be supported simultaneously. Therefore, we proposed a joint spectrum and power allocation with an admission control algorithm whose better complexity and performance than the ones which have been proposed in the existing algorithms in the literature. The performance of the proposed algorithm is compared using the metrics such as sum throughput, PU SINR, algorithm running time and SU SINR less than threshold and the results show that the PSOFAGA with ELGR admission control algorithm has best performance compared to GA, PSO, FA, and FAGAPSO algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1519-1527
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• 2007

In order to combat the security threats that sensor networks are exposed to, a cryptography protocol is implemented at sensor nodes for point-to-point encryption between nodes. Given that nodes have limited resources, symmetric cryptography that is proven to be efficient for low power devices is implemented. Data protection is integrated into a sensor's packet by the means of symmetric encryption with the Dragon stream cipher and incorporating the newly designed Dragon-MAC Message Authentication Code. The proposed algorithm was designed to employ some of the data already computed by the underlying Dragon stream cipher for the purpose of minimizing the computational cost of the operations required by the MAC algorithm. In view that Dragon is a word based stream cipher with a fast key stream generation, it is very suitable for a constrained environment. Our protocol regarded the entity authentication and message authentication through the implementation of authenticated encryption scheme in wireless sensor nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.233-241
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• 2013

One fundamental issue in ad hoc networks is the alternative node election problem, which reflects how well a sensor network is monitored or tracked by sensors. In this paper, we proposed EEAP(Energy-Efficient Alternative Paths). This is a method of selecting an alternative node for path routing management. When some node disconnection on the path routing, using pre-selected backup node provides immediately recover the path recovery. When selecting an alternative node of Step-Parents head node on the path management, the node's energy level and distance information are cared in context-awareness. This is not only increased the system's capacity cost effectively, but also reduce transmission power entire nodes consume energy. As a result, each node could efficiently management and improves the life time for mobile host and extends system coverage.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.1-11
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• 2015

WBAN(Wireless Body Area Network) operating around the human body aims at medical and non-medical service at the same time. and it is the short-range communication technology requiring low-power, various data rate and high reliability. Various studies is performing for IEEE 802.15.4, because IEEE 802.15.4 can provide high compatibility for operate WBAN among communication standard satisfiable these requirements. Meanwhile, in the case of coexisting many IEEE 802.15.4-based WBAN, signal interference and collision are the main cause that is decreasing data reliability. but IEEE 802.15.4 Standard does not consider about coexistence of many networks. so it needs improvement. In this paper, To solve about this problem, identify coexistence problem of IEEE 802.15.4-based WBAN by preliminary experiments. and propose a scheme to mitigate the reliability decrease at multiple coexistence WBAN. The proposed scheme can be classified in two steps. The first step is avoidance to collision on the CFP through improving data transmission. The second step is mitigation collision through converting channel access method. Proposed scheme is verified the performance by performing comparison experiment with Standard-based WBAN.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.298-306
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• 2016

With the advent of Internet of Things (IoT) technology that allows the communications between things and devices over the Internet, a lot of researches on the IoT services, such as smart home or healthcare, have been progressed. In the existing machine-to-machine (M2M) communications, however, since the underlying link-layer technologies, such as Bluetooth or ZigBee, do not use the Internet Protocol (IP) communication, those technologies are not suitable to provide the IoT services. Accordingly, this paper discusses how to provide the Internet services in the M2M communication, and propose an implementation of the Constrained Application Protocol (CoAP) over 6LoWPAN for providing IoT services in the BLE networks. Based on the implementation, we compared the performance between HTTP and CoAP for IoT communications. From the experimental results, we can see that the CoAP protocol gives better performance than the HTTP protocol with two times higher throughput, 21% faster transmission time, and 22% smaller amount of generated packets.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.25-36
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• 2016

The goal of the SmartGrid is to maximize energy efficiency by exchanging bi-directional real-time power information with the help of ICT(Information and Communication Technology). In this paper, we propose a "JRS-MS" (Joint Routing and Scheduling for Multi-channel SmartGrid) algorithm that uses numerical modeling methods in IEEE 802.11s based STDMA multi-channel SmartGrid NAN networks. The proposed algorithm controls the amount of data transmission adaptively at the link layer and finds a high data-rate path which has the least interference between traffic flows in multi-channel SmartGrid NAN networks. The proposed algorithm improve transmission performance by enhancing network utilization. By comparing the results of performance analysis between the proposed algorithm and the JRS-SG algorithm in the previous paper, we showed that the JRS-MS algorithm can improve transmission performance by maximally utilizing given network resources when the number of flows are increasing in the multi-hop NAN wireless mesh networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2769-2774
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• 2013

The key of USN(Ubiquitous Sensor Network) technology is low power wireless communication technology and proper resource allocation technology for efficient routing. The distinguished resource allocation method is needed for efficient routing in sensor network. To solve this problems, we propose an algorithm that can be adopted in USN with making up for weak points of PQ and WRR in this paper. The proposed algorithm produces the control discipline by the fuzzy theory to dynamically assign the weight of WRR scheduler with checking the Queue status of each class in sensor network. From simulation results, the proposed algorithm improves the packet loss rate of the EF class traffic to 6.5% by comparison with WRR scheduling method and that of the AF4 class traffic to 45% by comparison with PQ scheduling method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.660-665
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• 2018

Research into underwater wireless networks that enable the monitoring and controlling of the ocean environments has been continuing for disaster prevention and military proposes, as well as for the exploitation of ocean resources throughout the world. A research group led by Hoseo university has been studying a distributed underwater monitoring and controlling network. In this study, we developed an interpolator for acoustic communication between an underwater base station controller and underwater base station, which is included in this network. The underwater acoustic communication provided by this network defines four links whose sampling rates are different. Low power consumption is one of the most important requirements. Therefore, we adopted CIC interpolators, which are known to act as filters with a low power consumption, and some CIC interpolators with an appropriate changing rate were selected depending on the link. However, these interpolators have a large passband drop and wide transition region. To solve these problems, we added a compensator and half-band filter. After verifying the algorithm by using Matlab, we designed and verified it with Verilog-HDL in a ModelSim environment.

• Journal of Internet Computing and Services
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• v.5 no.2
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• pp.75-84
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• 2004

Geocasting, a variant of the conventional multicasting problem, is one of communication type in which the data packets are delivered to a group of all nodes within a specified geographical region (i.e., the geocasting region) and is called location-based multicasting(LBM)(l). An Ad-hoc network is a dynamically reconfigurable and temporary wireless network where all mobile devices using batteries as energy resources cooperatively maintain network connectivity without central administration or the assistance of base stations. Consequently, the technique to efficiently consume the limited amounts of energy resources is an important problem so that the system lifetime is maximized. In this paper, we propose a LBPA(Location-Based Power Aware) geocasting algorithm that selects energy-aware neighbor to route a packet towards the target region In Ad-hoc network environments. The method Is such that the energy consumption is balanced among the nodes in proportion to their energy reserves. Through the simulations, the proposed LBPA algorithm shows better results, that is, as good as 40% on the average over the conventional LBM algorithm in terms of the network lifetime.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.119-128
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• 2011

The Sensor technology and portable device capability able to collect recent user information and the information about the surrounding environment haven been highly developed. A user can be made use of various contents and the option is also extending with this technology development. In particular, the initial portable device had simply a call function, but now that has evolved into 'the 4th screen' which including movie, television, PC ability. also, in the past, a portable device to provided only the services of a SMS, in recent years, it provided to interactive video service, and it include technology which providing various contents. Also, it is rising as media which leading the consumption of contents, because it can be used anytime, anywhere. However, the contents available for the nature of user's handheld devices are limited. because it is very difficult for making the contents separately according to various device specification. To find a solution to this problem, the study on one contents from several device has been progressing. The contents conversion technology making use of the profile of device out of this study comes to the force and profile study has been progressing for this. Furthermore, Demand for a user is also increased and the study on the technology collecting, analyzing demands has been making active progress. And what is more, Grasping user's demands by making use of this technology and the study on the technology analyzing, providing contents has been making active progress as well. First of all, there is a method making good use of ZigBee, Bluetooth technology about the sensor for gathering user's information. ZigBee uses low-power digital radio for wireless headphone, wireless communication network, and being utilized for smart energy, automatic home system, wireless communication application and wireless sensor application. Bluetooth, as industry standards of PAN(Personal Area Networks), is being made of use of low power wireless device for the technology supporting data transmission such as drawing file, video file among Bluetooth device. With analyzing the collected information making use of this technology, it utilizes personalized service based on network knowledge developed by ETRI to service contents tailor-made for a user. Now that personalized service builds up network knowledge about user's various environments, the technology provides context friendly service constructed dynamically on the basis of this. The contents to service dynamically like this offer the contents that it converses with utilizing device profile to working well. Therefore, this paper suggests the system as follow. It collects the information, for example of user's sensitivity, context and location by using sensor technology, and generates the profile as a means of collected information as sensor. It collects the user's propensity to the information by user's input and event and generates profile in the same way besides the gathered information by sensor. Device transmits a generated profile and the profile about a device specification to proxy server. And proxy server transmits a profile to each profile management server. It analyzes profile in proxy server so that it selects the contents user demand and requests in contents server. Contents server receives a profile of user portable device from device profile server and converses the contents by using this. Original source code of contents convert into XML code using the device profile and XML code convert into source code available in user portable device. Thus, contents conversion process is terminated and user friendly system is completed as the user transmits optimal contents for user portable device.