• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2485-2487
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• 2015

Recently, Hashtag is widely used in SNS like Facebook, Twitter and personal blogs. However, the efficiency of tag search system is poor due to the indiscriminate use of hashtags. To enhance the accuracy of tag search system, we proposed a tag search system using the keyword extraction and similarity evaluation. The experimental results show that the proposed system provides the higher accuracy on tag search results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2389-2391
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• 2015

The feasibility condition of interference alignment (IA) for full-duplex (FD) multiple-input multipleoutput (MIMO) cellular networks is considered. The necessary and sufficient condition on the IA feasibility is established, characterizing the achievable sum degrees of freedom (DoF). The results demonstrate that FD operation with appropriate IA is able to improve the sum DoF on the conventional half-duplex operation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2410-2418
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• 2015

In this paper, we consider the femto users and their mutual interference as graph elements, nodes and weighted edges, respectively. The total bandwidth is divided into a number of resource blocks (RBs) and these are assigned to the femto user equipment (FUEs) using a graph coloring algorithm. In addition, resources blocks are assigned to the femto users to avoid inter-cell interference. The proposed scheme is compared with the traditional scheduling schemes in terms of throughput and fairness and performance improvement is achieved by exploiting the graph coloring scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2419-2426
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• 2015

Named Data Networking (NDN) is one of the powerfully evolving future internet architectures. In this paper installation, configuration and several tests are addressed to show how well and properly our NDN testbed have been prepared and established using NDN platform, in order to have interoperability with global NDN testbed. Global NDN testbed status with our NDN node participation was addressed. To verify one reachability on the NDN connection to global NDN testbed, a latency result is presented using NDN ping test.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.471-476
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• 2011

A improved system and protocol architecture for Personal Environment Service which has been created recently, is proposed in this paper. PES is the typical mobile convergence service based on smart phone and user profile, and its influence would be very huge in the near future. In order to make it feasible more efficiently, the system architecture should be studied from the early stage. The proposed PES system and protocol architecture could be valuable reference for the further study and development of PES system and technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.511-516
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• 2011

In this paper, we present the AMI System mentioned as one of the main application areas in the M2M. To enable the AMI, it is essentially required to install, deploy and manage all the devices. Especially, Device Management technology is considered to be suitable for these AMI due to its advantages like, easy installation, remote FW/SW upgradeability. We investigate the fundamental operation of the DM and the design of the DM in the AMI is presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2B
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• pp.141-147
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• 2011

In this paper, field trials for co-sited transmitters with 600kHz channel separation are performed to investigate the available FM spectrum resource of Korea. Requirements of subjective voice quality and electric field intensity levels are quite well fulfilled during overall field trials. Experimental results show that 600kHz channel separation in co-sited transmitter can be permitted after reasonable pre-simulation and field trial.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.771-773
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• 2014

Dual-polarization antenna system has been being researched for wireless communications under short range line-of-sight channel environments. In this paper, probability density function of signal-to-interference-ratio(SIR) for the dual-polarization antenna system is derived, and SIR outage is analyzed. It is shown that the upper bound capacity of a dual-polarization antenna system without polarization alignment is 4.5324 bps/hz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.777-779
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• 2014

In this paper, we consider IOTA-OFDM/OQAM system that improves the transmission power and rate efficiency of conventional OFDM system and propose DF relaying cooperative communication scheme based on the IOTA-OFDM/OQAM system. In the proposed scheme, the destination receives orthogonal signals from source and relay simultaneously and combines using MRC. We demonstrated that the proposed schemes get better BER performance than conventional system because of the diversity gain.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.774-776
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• 2014

In this paper, we propose a multiple dual-polarized antenna system for multi-user transmission in line-of-sight (LoS) dominant channel environments. By exploiting space and polarization resources efficiently, the proposed system achieves a higher sum rate than the existing multi-user multiple input multiple output (MU-MIMO) system with uni-polarized antennas.