• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.17-24
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• 2007

SIP-based tightly coupled conference, which has a centrally located conference server for controlling and management, can be classified several models according to location of focus and mixer. These are centralized server model, endpoint server model, media server component model and distributed mixing model. However each model has its strength and weakness. In this paper, we propose and implement a SIP-based effective hybrid-type conference model which decreases amount of SIP signaling messages, lowers load of server media mixer, and can be easily expandable to large scale conference. In this model, when the number of participants exceeds a pre-defined limit, the conference server selects some participants which posses specific functions and let them share functions of notifications of conference state event package and media mixing. When each participant subscribes conference state event package to the server, it can indicates its possession of such functions by a specific header message. The server stores the indication to the conference information database, and later uses it to select participants for load sharing. The performance of our proposed model is evaluated by experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.572-575
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• 2003

Mutimedia conference technology provides conference service as well as data service via Internet. Many standards and related applications were developed based on H.323 protocol. but H.323 protocol more complex than SIP. so IETF have developed standard that related conference control based on SIP. In this paper, we design conference event package for conference system based on SIP protocol.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.67-73
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• 2012

A distributed conference architecture with a new load control method has been suggested in this paper. A new event package in this paper enables to control conference load. Some additional elements for exchanging SIP messages between server and participants, and for distributing the load, have been added to new conference information data format. Furthermore to lessen the load, all conference servers share the processing of conference information data which should be transferred periodically to all participants. The suggested load control event package makes each server can get current load status of the overall servers. When load increases in one server SIP client requests are distributed by selecting a server which has the lowest load value, or new server is created to share the load. The performance of the proposed system has been evaluated by experiments. They shows 21.6% increase in average delay time, and 29.2% increase in average SIP message processing time.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.257-266
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• 2005

As developing of the internet and computer technology, more interests are gathered to the conference service which provides capability of multi-party real-time visual conference. In this paper, we have designed and implemented a SIP-based visual conference system which includes Presence service. The elements of this conference system are user system, which has conference UA(User Agent) capability, presence seuer and conference server. For the presence service, we have adapted publication method which uses SIP PUBLISH message, and with this service various status informations of users are easily acquired. Also invitations and involvements to the conference are easily made through this service. For the conference server which controls establishment and management of multi-party connections, we have included conference event package. This package provides dynamically changing conference informations and users informations through SIP subscription and notification functions.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.51-59
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• 2005

In this paper, we propose and implement a hybrid-type video conference system using SIP protocol proposed in IEFT. This conference system, all signaling is controled by the server, while the media communication can be managed either by UAs or by the server. as a result, the complexity of its routing and user state management is reduced and it is applicable to the mobile environment of the ad-hoc models. The implemented server is scale enough to be used in a large conference because it only takes charge of signaling part. And also we see that UAs are only suitable in the small conference where less than ten people can join.

• Korea Logistics Conference
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• v.14 no.2
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• pp.115-128
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• 2006

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.521-524
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• 2008

기존 지능망 서비스들이 포화 상태에 이르게 됨에 따라 수익이 나는 새로운 서비스를 개발하는 것이 점점 더 어려워지고 있다. 요즈음 전통적인 전화망과 인터넷의 결합이 새로운 경향으로 나타나고 있다. PC와 같은 인터넷 단말은 전화망의 전통적인 단말보다 저장 장치 및 유저 인터페이스 면에서 더욱 더 강력한 능력을 가지고 있다. IT 개발자들은 전화 분야의 전문 지식을 갖고 있지 않아도 Parlay API를 사용하면 새로운 통신 서비스를 쉽게 만들수 있다. HTTP 상의 SOAP을 사용하여 쉽게 두 컴퓨터 노드간의 통신이 가능하게 할 수 있더라도 일반적인 개발자는 현란한 XML 포맷 때문에 SOAP 메시지를 처리하는데 어려움을 느낀다. REST 기반 API는 이러한 것의 좋은 대체재가 될 수 있는데, 추가적인 프로토콜 층이 없이 HTTP 층만 있기 때문이다. 본 논문에서는 통화 및 메시징 서비스를 만들기 위한 REST 기반의 Open APl 를 소개한다. 제안되는 API는 클릭투콜, 미니 컨퍼런스, 통화 녹음, 주문형 오디오 재생, 단문 메시징 및 음성 메시징 기능을 제공한다. 제안되는 API 특징은 전화망과 인터넷의 컨버전스의 강력함을 보여준다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.121-122
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• 2023

As containerized maritime transport began in earnest, the size of container ships has steadily increased, and recently, the operation of 24,000 TEU-class vessels has become regular. However, concerns about the efficiency and productivity of such mega container ships from a port operational perspective have continued to be raised. The 10^th Busan International Port Conference requested an in-depth study on the trends of container ship enlargement by analyzing the order status of ultra-large container ships from major global liners. Generally, the factor that drives the upsizing of ships is the realization of economies of scale that lowers transportation costs per TEU, which leads to a higher level of cost reduction per unit transportation compared to the increase in fuel consumption due to transporting large amounts of cargo with a single ship. However, it is necessary to examine whether this trend of container vessel enlargement is feasible for port operations. To this end, this study compares and analyzes the productivity and efficeiency of different ship sizes to evaluate the effect of ship size on port operations.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.72-73
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• 2023

As containerized maritime transport began in earnest, the size of container ships has steadily increased, and recently, the operation of 24,000 TEU-class vessels has become regular. However, concerns about the efficiency and productivity of such mega container ships from a port operational perspective have continued to be raised. The 10th Busan International Port Conference requested an in-depth study on the trends of container ship enlargement by analyzing the order status of ultra-large container ships from major global liners. Generally, the factor that drives the upsizing of ships is the realization of economies of scale that lowers transportation costs per TEU, which leads to a higher level of cost reduction per unit transportation compared to the increase in fuel consumption due to transporting large amounts of cargo with a single ship. However, it is necessary to examine whether this trend of container vessel enlargement is feasible for port operations. To this end, this study compares and analyzes the productivity and efficeiency of different ship sizes to evaluate the effect of ship size on port operations.