• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8B
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• pp.492-501
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• 2007

UMTS-WLAN interworking approach can make the best use of the advantages of both networks by eliminating the stand-alone defects of the two services. For the interworking mechanisms of WLANs and UMTS networks, two major solutions have been proposed, namely loose coupling and tight coupling. The loose coupling approach provides separate data paths for WLAN and UMTS. On the other hand, the tight coupling provides a full integration of the WLAN network and the UMTS core network. The loose coupling has been preferred due to the simplicity and less reconfiguration requirement. However, loose coupling is worse in seamless mobility, QoS provision, and network security. In order to lessen the problems involved in the UMTS-WLAN interworking approaches, we propose a new interworking network architecture and a fast vertical handover scheme by employing Mobility Anchor(MA) for interworking between the two different networks. MA can enable authentication and session initialization before L2 handover of the mobile terminal, so that the seamless and fast vertical handover become possible. Thru analysis and numerical experiments, we proved that the proposed scheme has been validated.

• The Korean Journal of Applied Statistics
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• v.21 no.5
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• pp.791-799
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• 2008

Ansim Flat DATA Plan is a DATA additional service product related to DATA call in a mobile telephone company A. Up to now, the company A is selling it by outbound TM after targeting customers which used data within specific price band. In this paper, we propose a targeting method applying score model combining response rate and retention rate by data mining. The suggested target model is to find customers more likely not only to respond to outbound TM but also to retain Ansim Flat DATA Plan. The proposed targeting method is expected to improve both from 23.7% to 38.8% in the response rate and from 53.2% to 61.4% in the retention rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1394-1401
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• 2008

This work investigates the effects of vibration on the passive intermodulation distortion characteristics of base station antennas for 800 MHz CDMA mobile communication systems. In general, base station antennas are located at high positions such as on building rooftops or iron towers. Thus the antennas are always affected by random vibrations, coming from various natural environmental factors such as rain and wind, or from living environmental factors such as vehicles and trains passing by. The measured intermodulation distortion characteristics before and after vibration accelerated degradation test show that vibrations are indeed the main cause for the intermodulation distortion performances of such antennas. To minimize the effects of vibrations, a new antenna design isptoposed that has an improved tolerance for vibrations. Experimental results show that the proposed antenna design dramatically reduces the degradation of the intermodulation distortion more than 35 dB.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.251-264
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• 2016

The purpose of this study is to compose direction about mUC as a communication channel in the company. Recently, many companies have started to adopt or try to vitalize the use of mUC. This study starts from the viewpoint of communication which is the original purpose of SNS or mUC. The purpose and function of life-world are drawn based on Habermas' theory of communicative action. Firstly, this study will check on a difference in usage over the action and articulation between SNS and mUC. Secondly, this study will examine a difference of effect of life-world between SNS and mUC. Thirdly, to check that there is difference according to the user characteristics. The result is that there are differences about action and articulation but little differences of effect to the life-world between SNS and mUC. Also, there is difference according to the user characteristics. This study could contribute to compose direction when a company adopts or vitalizes mUC.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.549-557
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• 2015

Mobile cellular networks are becoming increasingly complex to manage while classical deployment/optimization techniques and current solutions (i.e., cell densification, acquiring more spectrum, etc.) are cost-ineffective and thus seen as stopgaps. This calls for development of novel approaches that leverage recent advances in storage/memory, context-awareness, edge/cloud computing, and falls into framework of big data. However, the big data by itself is yet another complex phenomena to handle and comes with its notorious 4V: Velocity, voracity, volume, and variety. In this work, we address these issues in optimization of 5G wireless networks via the notion of proactive caching at the base stations. In particular, we investigate the gains of proactive caching in terms of backhaul offloadings and request satisfactions, while tackling the large-amount of available data for content popularity estimation. In order to estimate the content popularity, we first collect users' mobile traffic data from a Turkish telecom operator from several base stations in hours of time interval. Then, an analysis is carried out locally on a big data platformand the gains of proactive caching at the base stations are investigated via numerical simulations. It turns out that several gains are possible depending on the level of available information and storage size. For instance, with 10% of content ratings and 15.4Gbyte of storage size (87%of total catalog size), proactive caching achieves 100% of request satisfaction and offloads 98% of the backhaul when considering 16 base stations.

• Journal of Digital Contents Society
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• v.18 no.8
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• pp.1543-1550
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• 2017

Previous research on smartphone has been focused on personal performance, accessibility, and information gaps in information system quality. In order to analyze the relationship between the use of smartphone information and personal characteristics, this study conducted a survey of 300 tourists at Jeju Airport, by using three variables of self-efficacy, 'impulsiveness and demographic variables (age, sex, education level, etc.) of smartphone use with personal characteristics. In conclusion, self-efficacy and impulsiveness seem to be positively related to the use of smartphone because it seems to be a living environment in which the desired information can be acquired within a desired time. In addition, there seems to be a difference between a mobile native environment in which online and offline boundaries are always connected and an environment in which 40 to 50 digital literacies are connected. This can be interpreted as a result of additional analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.390-396
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• 2015

The drastic growth of mobile communication and spreading of smart phone make the significant attention on Location Based Service. The one of most important things for vitalizations of LBS is the accurate estimating position for mobile object. Focusing on an image sensor deployed in smart phone, we develop a LED based positioning estimation framework. The developed approaches can strengthen the advantages of independent indoor applicability of LED. The estimation of LED based positioning is effectively applied to any indoor environment. We put a focus especially on the algorithmic framework. of image processing of smart phone. From LED lighting, we can obtain a typical signal image which contains the unique positioning information. Furthermore test-bed based on smart phone platform is practically developed and all data have been harvested from the actual measurement of test indoor area. This can approve the practical usefulness of proposed framework.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2762-2767
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• 2011

With increasing use of wireless mobile devices like smartphone and tablet PC, telecommunication companies have been providing the internet service by installing a multitude of access points (AP) in subway stations. Most of these APs use frequency of 2.4 GHz band range and the three telecom providers (SKT, KT, LGT) are using the limited channels within this range without any regulations. The channels within 2.4GHz band are already saturated as the companies are setting up wireless AP even within the subway trains for better service. This can affect other 2.4GHz wireless devices used for other purposes with channel interference, etc. This study has tested and analyzed the effects of the wireless APs installed within the subway stations and trains for the internet service on ZigBee-based sensor network for the intelligent surveillance system of urban transit, which is currently being developed and installed.

• Information Systems Review
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• v.8 no.1
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• pp.25-41
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• 2006

This paper is about how to drive a Business Process Management(BPM) implementation project from selecting a target process to BPM deployment. For guidance of BPM implementation, LG CNS BPM Methodology and enPAM(Entrue Process Assessment Model) were used. This paper focuses on the methodology of process selection and presents a case study from the telecommunication industry. The enPAM consists of three major criteria in determining process priority for BPM system deployment: business impact, BPM adequateness and implementation feasibility. These three criteria can be easily modified for other telecommunication business just as we did to suit this telecom case. Moreover, it could provide useful ideas to companies that consider introducing a BPM solution for process management. Although we propose a comprehensive design methodology for selecting a proper target business process for BPM implementation, more work is still needed to extend the results for rigorous and practical method.

• The Korean Journal of Applied Statistics
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• v.24 no.6
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• pp.1237-1248
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• 2011

Social network analysis(SNA) has been recently applied to business areas such as social network services (such as Facebook and Twitter). In addition, the mobile telecommunication field attempts to analyze CDR(call detail record) data and apply customer relationship management and customer churn management through the use of social network analysis. The paper analyzes links between ego and alter based on ego-network and discovers four kinds of customer roles and then provides insights as a tool for customer relationship management or customer management.