• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.128-137
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• 2006

Recently, the combination of WLAN and 3G wireless technologies will make MMS service more ubiquitous, bringing benefits to both service providers and their customers. To realize seamless MMS service over WLAN and CDMA2000 networks, we design novel seamless interworking architecture by reusing the existing standards and network elements at the same time. Based on the proposed seamless interworking architecture, we also present seamless notification architecture and seamless handover architecture that can't be possible within current MMS reference architecture. This paper will make a contribution for service providers to provide their customers with seamless MMS service over WLAN and CDMA2000 networks.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.68-73
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• 2001

이동통신 시스템에서 지하 주차장, 지하상가, 터널, 빌딩내부등과 같이 기지국에 의한 신호의 커버리지가 충분하지 못한 지역들이 발생하게 된다. 이러한 영역의 경제적인 해결 방안으로 중계기가 널리 사용된다. 그러나, 중계기의 수가 증가할수록 역방향 링크의 기지국으로 유입되는 잡음 전력이 중계기의 숫자에 비례하여 증가하기 때문에 채널 용량이 감소하게 된다. 수십, 수백개의 중계기가 하나의 기지국에 연결되는 상황에서 이러한 채널 용량의 감소는 더 이상 무시할 수 없다. 본 논문에서는 커버리지 내에 통화중인 사용자가 없을 때에 자동적으로 동작하지 않는 스위칭 중계기를 제안하였다. 스위칭 중계기를 사용하면 중계기의 커버리지 내에 통화중인 사용자가 없을 때 불필요한 잡음 레벨을 줄일 수 있다. 스위칭 중계기를 사용한 이동통신 시스템의 역방향 링크 채널 용량을 수학적으로 분석하여 스위칭 중계기를 사용하지 않는 상황과 비교하였다. 그 결과 스위칭 중계기를 사용할 때 충분히 채널용량이 개선되었음을 알 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.140-148
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• 2017

This paper focused on finding a cost-effective LTE mobile network design methodology, suitable for socio-economic circumstances of developing countries. Developing countries have different requirements and circumstances compared with those of developed countries that had deployed LTE networks in advance, thus a differentiated way of design and deployment methods are necessary. This paper analyzed LTE design-related attributes of developing countries, identified relevant technological requirements and appropriate technologies, and suggested design methodologies. These suggestions were verified through the case studies of several developing countries that a Korean telecommunication company (Korean telecom company A) had participated in the LTE design and deployment for future reference by other developing countries.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.717-720
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• 2006

한국 국내에는 GVM(GNFX), WIPI, BREW, MIDP 등 다양한 모바일 플랫폼이 존재하고 있으며, 각 이동통신사별로 서로 다른 플랫폼을 채택하여 사용하고 있다. 이로 인해 개발자는 하나의 콘텐츠를 서비스하기 위하여 각 이동통신사들의 플랫폼에 맞추어서 다양한 버전의 콘텐츠를 개발하거나, 개발된 콘텐츠를 다른 플랫폼에 이식하기 위하여 콘텐츠를 변환하여야 한다. 이러한 이유로 콘텐츠 서비스를 위해 많은 시간과 비용이 소모되고 있으며, 모바일 사용자는 다양한 콘텐츠를 제공받지 못하고 있다. 본 연구팀은 이러한 문제점을 해결하기 위하여 콘텐츠를 자동으로 분석하여 변환해주는 콘텐츠 자동 변환기 시스템을 연구하였고, GVM 콘텐츠를 WIPI Java 콘텐츠로 자동으로 변환해주는 GVMC-to-WIPI Java 변환기를 설계하고 구현하였다. 본 변환기는 한번 개발한 콘텐츠를 단기간 내에 다른 플랫폼의 콘텐츠로 변환할 수 있도록 지원하여, 콘텐츠를 다른 플랫폼으로 이식하기 위한 개발 기간 및 비용을 단축시켜 준다. 또한, 모바일 사용자에게 다양한 콘텐츠를 제공할 수 있도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.379-383
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• 2000

인터넷에서 멀티캐스트 그룹 통신을 하고 있는 이동 호스트가 접속지점을 수시로 바꿈에 따라 지속적인 멀티캐스트 응용에 참여하기 위해서는 이웃하는 멀티캐스트 라우터를 찾아내어 연결을 유지시켜야 한다. 기존 연구들은 주로 멀티캐스트를 지원하는 환경에서만 고려된 것들이다. 그러나 오늘날 대부분 라우터들은 멀티캐스트 서비스를 지원하지 않으며, 기존 연구들에서는 이를 터널링으로 해결하였다. 그런데 터널링은 경로 최적화 문제를 안고 있으며, 호스트 이동성의 본질적인 특성인 투명한 라우팅과 최적의 경로설정에 위배되는 문제점을 안고 있다. 본 논문은 멀티캐스트 기능을 지원하지 않는 망에서도 이동 호스트에게 멀티캐스트 응용 서비스를 제공할 수 있는 MRM-IP 방법을 제안한다. 이 방법은 이동 호스트가 인터넷에서 멀티캐스트 라우터가 장착되지 않는 망으로 이동했을 때, 종단 호스트와의 최적 경로를 이루는 최하단 멀티캐스트 라우터를 찾아 그룹 멤버로 원격가입 함으로써, 유니캐스트 한다. 이는 IETF의 양방향 터널링과 원격가입의 장점만을 이용한 것으로, 경로 최적화 문제를 해결하여 망에서 트래픽 지연을 줄일 수 있다.

• Journal of Navigation and Port Research
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• v.45 no.5
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• pp.231-237
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• 2021

Enhancing the performance of maritime wireless communication has been highlighted by the issue of cell planning in the sea area because of lack of an appropriate Propagation Loss Model (PLM). To resolve the cell planning issue in vast sea areas, it was essential to develop the (PLM) matching the intended sea area. However, there were considerable gaps between the prediction of legacy PLMs and field measurement in propagation loss and there was a need to develop the adjusted PLM (A-PLM). Therefore, cell planning was performed on this adjusted model, including modification of the base station's location, altitude, and antenna azimuth to meet the quality objectives. Furthermore, in order to verify the availability of the cell planning, Communication Service Quality Monitoring System (CS-QMS) was developed in the LTE-Maritime project to collect LTE signal quality information from the onboard equipment at regular intervals and to ensure that the service quality was high enough to satisfy the goals in each designated grid. As a result of verification, the success rate of RSRP was 95.7% for the intensive management zone (IMZ) and 96.4% for the interested zone (IZ), respectively.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.1-11
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• 2018

The primary purpose of this study is to investigate whether Moon Jae-in administration's universal service policy of mobile date to lower communications fares can be justified. To do so, this work takes a look into the key features of mobile data in our society based on a theoretical perspective as well as a practical point of view. Also, it attempts to figure out whether mobile data service should be included in the scope of universal service in Korea by analysing the key features of mobile data and rethinking the basic concepts of universal service. As a result, this work reaches a conclusion that the government should reconsider universal service policy of mobile date and reform a universal service system in a different way.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.917-920
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• 2014

In Korea mobile phone subscribers exceeded 1 million people in 1995, and ten million people in 1998. Prevalence of the mobile phone increased dramatically over 110% compared to the population. And all family members including children and students use one or two mobile terminal. Mobile phone is obviously necessary good more than washer, vacuum cleaner, passenger car. Our daily life with mobile communication are conveniently positioned, but communication related costs including the price of the device has become a big burden on the household. But the government does not seem to do the right role at the right time to prevent the failure of the market to further maximize consumer welfare and social welfare through fair competition. This principal-agent problems exist especially in perspective of joint use of the mobile communication network, number portability, separation of phone distribution and phone service and network neutrality among in mobile communication policies since the early 1990s up to now.

• ETRI Journal
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• v.31 no.1
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• pp.51-61
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• 2009

We present a unified explanation of the internationalization strategies of major mobile network operators (MNOs). We have developed a framework that analyzes the strategies of major international MNOs in terms of the relationship between their degree of involvement in international business operations and the degree of equity participation. The results show a positive association between these two dimensions as expected, but they also reveal some exceptional cases in which certain MNOs are actively involved in the business operations of other foreign MNOs, even with minor (or zero) equity investments. In this paper, we argue that the strategic actions of the major MNOs which are the largest shareholders of foreign MNOs are in an equilibrium status because these major MNOs derive maximum benefit from full or considerable management control and active involvement. Finally, we predict that latecomers (MNOs who are just about to enter foreign telecommunications markets) may adopt an incremental investment approach because most developed markets and deregulated emerging markets with growth potential are already preempted by major MNOs. Therefore, the window of opportunity for internationalization in those markets is currently small.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1893-1900
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• 2015

The government has the responsibility to prevent abuses of monopoly and promote competition in order to maximize consumer welfare. The government should address the asymmetry in the information as much as possible and ensure consumer choice. The subsidy seems to reduce the burden on the consumer service charges and handset prices but it actually distorts the market through price discrimination. The government caused the principal-agent problem by neglecting their appropriate role to prevent distortion of the mobile telecom market. The money used as subsidy is part of excess profit and could be transferred to down the price of mobile phone and charges and it would become a benefit to consumers. Separate announcement of subsidies by Mobile Communications Terminal Distribution Structure Improvement Act is a little developed policy but it was not actually realized. The market price close to that from perfect competition structure is plausible, ultimately.