• International Journal of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.48-53
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• 2016

Noise and vibration pollution is emerging to people in high speed trains. And it is difficult to realization of eco-friendly railway system at noise problem. The railway internal noise is 73dB on average and over 80dB in the loudest section. In order to reduce noise, there are passive methods that are far from noise sources and theother active noise reducion method. In this paper, we propose a method of reduce noise by measure and estimate the noise condition of train environment using Bone-Conduction device. We use an anti-phase waveform for canceling of noise characteristic. With this new system, the noise from surrounding environments can be reduced.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.442-447
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• 2010

For the remarkable enhancement of high-speed rail passenger services, a system which provides various multimedia contents and Internet search functions was designed. The system gets inputs from a passenger and displays various multimedia contents on the touch sensitive LCD panel attached on a passenger seat. This kind of service is new in Korea and not easy to find in other countries, either. In this paper, we presented a design of a system which provides not only one-way broadcasting services but also searching capability of various information interactively. Informations to be provided are train schedule, transfer information, tour information, E-books, movies, music, ets. Successful completion of the system development in the following years is expected to strengthen international competitiveness of Korean railway industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.3
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• pp.508-522
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• 2011

Femtocell is an economical solution to provide high speed indoor communication instead of the conventional macro-cellular networks. Especially, OFDMA femtocell is considered in the next generation cellular network such as 3GPP LTE and mobile WiMAX system. Although the femtocell has great advantages to accommodate indoor users, interference management problem is a critical issue to operate femtocell network. Existing OFDMA resource management algorithms only consider optimizing system-centric metric, and cannot manage the co-channel interference. Moreover, it is hard to cooperate with other femtocells to control the interference, since the self-configurable characteristics of femtocell. This paper proposes a novel interference-aware resource allocation algorithm for OFDMA femtocell networks. The proposed algorithm allocates resources according to a new objective function which reflects the effect of interference, and the heuristic algorithm is also introduced to reduce the complexity of the original problem. The Monte-Carlo simulation is performed to evaluate the performance of the proposed algorithm compared to the existing solutions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4098-4116
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• 2020

Mobile devices such as smartphones are very attractive targets for augmented reality (AR) services, but their limited resources make it difficult to increase the number of objects to be recognized. When the recognition process is scaled to a large number of objects, it typically requires significant computation time and memory. Therefore, most large-scale mobile AR systems rely on a server to outsource recognition process to a high-performance PC, but this limits the scenarios available in the AR services. As a part of realizing large-scale standalone mobile AR, this paper presents a solution to the problem of accuracy, memory, and speed for large-scale object recognition. To this end, we design our own basic feature and realize spatial locality, selective feature extraction, rough pose estimation, and selective feature matching. Experiments are performed to verify the appropriateness of the proposed method for realizing large-scale standalone mobile AR in terms of efficiency and accuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3837-3859
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• 2014

Vehicular Ad hoc Networks (VANET) becomes more popular in industry, academia and government. However, Typical VANET is challenged by high speed mobility and insufficient spectrum resources over congested scenarios. To address those serious problems, some articles have introduced Cognitive Radio (CR) technology into VANET and formed CR-VANET. In this article, we propose an overview of CR-VANET by exploring different architectures and features. Moreover, we provide taxonomy of state-of-the-art papers in this emerging field and the key articles are well analyzed respectively. In addition, we illustrate both research and application frameworks of CR-VANET based on our works, and propose some open research issues for inspiring future work.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1367-1370
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• 2002

This paper introduces a new web based method to remotely upgrade firmwares of Cable Modems (CM) which are integral part in providing high-speed Internet access through Hybrid Fiber Coaxial (HFC) networks. Also, it discusses various practical problems arising in the upgrading process. Traditional upgrade has been performed by modifying the CM configuration fie. This paper shows a new web based CM firmware upgrade method using SNMP and MIB which greatly reduces upgrading time, cost and man-hour than traditional firmware upgrade methods. This method has been shown to be very efficient and practical. This method will make significant impact especially because tens of million cable modems are currently waiting to be upgraded soon to the next version from the current version.

• ETRI Journal
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• v.26 no.1
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• pp.48-52
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• 2004

In this letter, we consider a new packet scheduling algorithm for an orthogonal frequency division multiplexing access/frequency division duplex (OFDMA/FDD)-based system, e.g., mobile broadband wireless access or high-speed portable internet systems, in which the radio resources of both time and frequency slots are dynamically shared by all users under a proper scheduling policy. Our design objective is to increase the number of non-realtime service (e.g., WWW) users that can be supported in the system, especially when the minimum bit rate requirement is imposed on them. The simulation results show that our proposed algorithm can provide a significant improvement in the average outage probability performance for the NRT service, i.e., significantly increasing the number of NRT users without much compromising of the cell throughput.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.575-580
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• 2017

In these days, the big-size and high resolution multimedia file is widely used through networks. To transfer and service effectively, the internet network technology is necessary to substitute broadcasting. Normally Content Delivery Network(CDN) is widely used in conventional internet for multimedia services. But it has a small bandwidth to service. So to solve this problems, many researchers have suggest the protocol for download, content distribution/saving, server synchronization, caching, pushing rate, and streaming etc. But all of these has some defects like low resolution, packets loss and delay, real application implementations etc. So, this paper suggests a new method of network protocol based on P2P collaboration and user's content using information. And it evaluated the performance of suggested method. As the results, it showed the effectiveness of 4 performances indices : download speed, decreasing rate of connected user in same time, adaptive hit ratio, traffic decreasing rate.

• Journal of Internet of Things and Convergence
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• v.1 no.1
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• pp.11-19
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• 2015

The mobile and ubiquitous environment is experiencing a rapid development of information and communications technology as it provides an ever increasing flow of information. Particularly, GIS is now widely applied in daily life due to its high accuracy and functionality. GIS information is utilized through the tiling method, which divides and manages large-scale map information. The tiling method manages map information and additional information to allow overlay, so as to facilitate quick access to tiled data. Unlike past studies, this paper proposes a new architecture and algorithms for tile searching and indexing management to optimize map information and additional information for GIS mobile applications. Since this involves the processing of large-scale information and continuous information changes, information is clustered for rapid processing. In addition, data size is minimized to overcome the constrained performance associated with mobile devices. Our system has been implemented in actual services, leading to a twofold increase in performance in terms of processing speed and mobile bandwidth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.446-452
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• 2005

As the name means, the WiBro is mobile service so that radio internet connection may be possible with high transmission speed using various terminal. Because WiBro is choosing suitable All-lP network architecture in internet service offer, structure of network is simple and the various supplementary service offer is available. This paper presented mobility model of terminal and proposed efficient way to improve existent way that transfer efficiency drops by data padding and analyze the performance by simulation.