• Annual Conference of KIPS
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• 2002.11b
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• pp.1301-1304
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• 2002

통신 환경이 변하면서, 기존의 서비스에 따라 크게 음성망과 패킷망으로 구분되던 망 구조가 하나의 통합된 망에서 모든 서비스를 제공하는 구조로 진화하고 있다. 그리고, 이러한 서비스를 가능하게 하는 기술로서 VoIP(Voice over IP)가 최근까지도 계속 각광받고 있다. 그러나, 많은 노력에도 불구하고, 음성서비스와 같은 실시간 서비스의 엄격한 품질 요구조건을 보장하는 문제 때문에 VoIP 기술의 실제 적용이 지연되고 있다. 이에 본 논문에서는 통합망의 패킷 전달망을 ACE2000 MPLS 시스템 기반의 MPLS 망으로 구축함으로써 음성서비스의 품질을 보장하는 망 구조를 제시하고자 한다. 아울러 TE Server를 이용해서, 음성호를 전달하는 ER-LSP(Explicit Routed Label Switched Path)를 설정하는 호 설정 절차를 제시하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.601-603
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• 2001

기존의 전화망과 달리 VoIP(Voice over IP)기술은 저렴한 통화 서비스를 가능하게 해주며, 다양한 멀티미디어 서비스를 제공해 줄 수 있다는 장점을 가지고 있어 현재 이와 관련한 개발이 활발히 진행 중에 있다. 그런데, 대부분의 VoIP시스템이 ITU-T에서 제안한 H.323을 표준으로 삼아 구현되었으나, H.323은 랜(LAN)환경에서 개발된 기술 방식이므로 이에 따른 구조적인 한계점을 가지고 있다. 반면, IETF에서 제안만 SIP(Session Initiation Protocol)의 경우는 내용이 간단하고 구현이 쉬울 뿐 아니라 확장성과 포괄성 측면에서 구조적인 문제점을 해결할 수 있는 대안으로 제시되어 지고 있다. 본 논문에서는 SIP을 기반으로 한 User Agent와 부재중 음성 메일 서비스의 설계 및 구현에 대해 설명한다. User agent간에는 실시간 음성 및 화상 통화가 가능하며 상대방이 부재중일 경우에는 상대에게 음성 메일을 전송할 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.293-300
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• 2007

As the development of the various IP-based services, it is expected that Internet telephony service will gradually replace the traditional PSTN-based telephony service. But there are many issues resolved to spread the Internet telephony service. One of them is to support the emergency services in the Internet telephony. In the case of USA, it has been regulated that 911 services should be supported in the Internet telephony services using VoIP on the similar performance level to PSTN 911 service. According to the regulation, basic VoIP 911 calls should be routed to the general access line of LEA without the location information or the callback number, but the enhanced VoIP 911 calls with the location information and callback number should be routed on the dedicated 911 network and destined to the local 911 distribution center such as PSAP. But, in the current VoIP-based Internet telephony network, the emergency call service has not been handled as one of the special services as well at has a worse performance in comparison to it on PSTN. Moreover, the service has a critical problem that it can not be destined to the nearest PSAP because of the insufficient information about the location information and the call back number. In this paper, we suggest the SIP-based emergency call service mechanism in order to resolve the problems above mentioned. This suggested mechanism is implemented to show its effectiveness and efficiency.

• The Journal of the Korea Contents Association
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• v.2 no.3
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• pp.119-126
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• 2002

The QoS(Quality of Service) guarantee mechanism is one of critical issues in the wireless network. Real-time applications like VoIP(Voice over IP) in All-IP networks need smooth handoffs in order to minimize or eliminate packet loss as a Mobile Host(MH) transitions between network links. In this paper, we design a new multicasting algorithm using DB(Dynamic Buffering) mechanism for Mobile-IPv6. A key feature of the new protocol is the concepts of the DB and MRA(Multicast Routing Agent) to reduce delivery path length of the multicast datagram. Particularly, the number of tunneling and average routing length of datagram are reduced relatively, the multicast traffic load is also decreased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.92-100
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• 2016

It is informed that the Voice over LTE(VoLTE) which serves voice and message on IP networks is better in terms of economies of scale than the legacy voice service on 2G/3G circuit-switched networks because of its technological and cost efficiency. In addition, services of voice and data are running on a single LTE network and as a result VoLTE has the more economies of scope. But, there is no study about how much technology-efficiency VoLTE has compared to circuit-based voice service and how much voice charge can be reduced as VoLTE grows up. This paper analyzes empirically cost-efficiency of VoLTE against circuit-based voice service and quantifies the reduction of voice charge as 2G/3G voice traffic shifts to VoLTE. The results describe the first is that the average cost of the total voice traffic rises shortly just after the investment of LTE network for providing VoLTE but it will soon have a capacity available to reduce the charge due to VoLTE's outstanding cost efficiency on the assumption that voice traffic is fixed, and the second is that the charge can be cut to 60% of the current rate in case of all the voice traffic moves to VoLTE. The latter proves partially the validation of data-focusing pricing plan. Our results are expected to become basic data for network operators' establishing pricing strategies and for policy makers' inducing price cutting.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.2078-2083
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• 2012

Tactical communication environment evolving for the purpose of providing services such as voice, video and text based on ALL-IP. Therefore, To be able to guarantee QoS level which meets the required level of subscriber for these services in the constrained tactical communication infrastructure, it is required to take the characteristics such as wireless transmission link, mobility of troops or personal into service quality scheme. In this paper, to support differentiated QoS for each individual or mission in the tactical communication environment, we presents a technique that can provide same QoS level which was served originally regardless of the situation to user's move through dynamically determining the QoS level to be provided at the time of the service request on VoIP-Switch.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1700-1709
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• 2006

In this raper we researched on the development methods and design of the B-ISDN protocol embedded IP-PBX System with the computers interconnected by the Internet for the previous telephone exchange and communication. We designed the structure of the user terminal and exchange sewer of the IP-PBX System, defined message and data structure for call control, and designed call control state transition and call control message flows for user's communication. And we researched on the message flows for supplementary services and the call control for multiple calls.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1296-1304
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• 2007

In this paper we researched on the implementation of the B-ISDN protocol embedded IP-PBX System with the computers interconnected by the Internet for the telephone exchange and multimedia communication. For the improvement on the structural problems of the previous PABX we designed the structure of the IP-PBX System, defined message and data structure for call control, designed call control state transition, and implemented call control message flows for user's communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2256-2264
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• 2007

In this paper we researched on the implementation of the B-ISDN protocol embedded IP-PBX System with the computers interconnected by the Internet for the telephone exchange and multimedia communication. For the improvement on the structural problems of the previous PABX we designed the structure of the IP-PBX System, defined message and data structure for call control, designed call control state transition and implemented call control message flows for user's communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2391-2398
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• 2011

National Information and Communication Services of Public Administration and Security organized by the 'A 'group (Line service network), 'B' group (IP service network), 'C' Group (Voice over Internet protocol(VoIP) service, IP application services) are provided by constructing the infrastructure. National Information and Communications Services 'C' group, providers are providing VoIP services. In this paper, national information and communications service 'C' group, providers of domestic calls, international calls, including calls to move we will study the basic telephone service. And text messaging, video telephony, IP-Centrex services, etc. we will study the seven value-added services. In addition, national information and communication service providers on the status of the project based on the analysis of national information and communication Internet telephone network using Internet telephony is the type of analysis. In this study, national information and communications services industry, will serve as the basis for the development.