• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.293-302
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• 2013

Home network providers have many worries about providing home network services with an expandable, reliable, flexible and low-cost structure according to the expanding market environment. The existing client-server system has various problems such as complexity and high costs in providing home network services. In this paper we propose the P2P-SIP structure. P2P communication terminal supporting access of distributed resources provides functions which the existing SIP-based network devices have. Because diverse terminals in a home network access through networks, also, partitioning network domains with home gateways to manage, and applying the network-based PMIPv6(Proxy Mobile IPv6) technology considering mobility of terminals would help to have a more efficient home network structure. Especially, the proposed P2P-SIP structure proves itself as a very efficient structure to have an outstanding expandability among different home networks in a region, and to reduce maintenance costs.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.4
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• pp.115-124
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• 2014

Since it costs a lot to build a home network system of new service provider, the entry barrier is quite high. If it would be possible to build a home network system with high performance at a low building cost, it would be quite attractive. If a home network would be built in P2P-SIP(Peer to peer - Session Initiation Protocol) structure, it is possible to decrease server maintenance cost and keep high usability by deconcentrating the traffic concentrated on the server. It is also possible to efficiently manage the location information of terminal, if quorum system based on fuzzy logic would be applied. In this paper we propose the P2P-SIP structure applied of quorum system based on fuzzy logic by which a home network system can be built at low cost. It was possible to know by comparing the structure with existing one that the structure has very good performance.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.65-72
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• 2008

Mobile Collaboration is an enabling technology that makes users share information between mobile devices and various Mobile P2P platforms have been designed and implemented for it. There are, however, few research papers on application of SIP protocol to spatial data sharing on mobile devices. In this paper, SIP based real time sharing framework is proposed to compose a mobile P2P platform on which spatial data can be trans(erred. A new protocol based on WKT and WKB is defined to send and receive spatial objects with SIP MESSAGE method. Base maps such as digital maps and parcel maps can be provided by a map server that is integrated with SIP server after a new SIP session established and client agents are registered. The framework proposed based onSIP enables users to transfer spatial data such as maps and satellite images directly between mobile devices during VoIP based voice call and therefore, mobile applications can be applied in various domains such asforest management and national defense.

• Journal of Pharmaceutical Investigation
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• v.30 no.4
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• pp.235-239
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• 2000

Ipriflavone (3-phenyl-7-isopropoxy-4H-1-benzopyran-4-one, IP) is a well-known antiosteoporotic drug with poor bioavailability. In the previous study, we reported that the IP formulation prepared by spray-drying method with polyvinylpyrrolidone (PVP) (SIP) was very effective in improving the bioavailability of IP. In this study, we examined the effects of molecular weight and mixture ratios of PVP to IP on the systemic absorption of IP following oral administration of SIP at a dose of 50 mg/kg to rats. In the effect of molecular weight, the Cmax of spray-dried IP with PVP K30 (SIP-K30) was significantly higher than those of spray-dried IP with PVP 360 (SIP-360), spray-dried IP with PVP K90 (SIP-K90), and spray-dried IP with PVP K17 (SIP-K17) (p<0.05). The AUC of SIP-K30 was about 2, 3, and 5.5 times higher than those of SIP-360, SIP-K90, and SIP-K17, respectively. The AUC value of SIP-K30 was significantly greater than those of SIP-K17 and SIP-K90 (p<0.05) except for SIP-360. In the ratio of PVP K30 to drug, the $C_{max}$ and the AUC value of 3 : 7 IP-PVP solid dispersion were similar to those of 5 : 5 IP-PVP and significantly higher than those of the other solid dispersions (p<0.05). It was concluded that the spray-dried IP with PVP K30 at the ratio of 3:7 (w/w) was the best formulation for improving the bioavailability of IP.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1285-1287
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• 2009

VoIP 통신에서 단말간의 세션을 수립하고 종료하는 역할을 하는 SIP는 기본적으로 서버-클라이언트 방식으로 이루어져있다. 하지만 이는 확장성과 설치비용, 단일실패 지점 측면에서 큰 단점을 갖는다. 최근에 DHT를 이용한 구조적인 P2P를 SIP와 결합하여 위의 단점들을 극복하기 위한 연구들이 활발히 진행되고 있다. 하지만 DHT를 이용한 방식은 기존 서버-클라이언트 방식에 비해 검색지연이 늘어난다는 큰 단점을 가지고 있다. 검색지연은 SIP에서 QoS의 중요한 지표중 하나인 호 설정 지연에 60~80% 정도의 큰 영향을 미치게 되므로 해결해야할 중요한 문제이다. P2PSIP에서는 종단 노드가 검색한 사용자의 주소를 캐싱하여 같은 사용자를 재 검색시에 사용하고 있다. 이는 네트워크 전체 오버헤드 감소에 큰 영향을 주지 못할뿐만 아니라 발생된 검색비용을 자신만이 사용할 수 있으므로 비효율적이다. 이에 본 논문에서는 도메인으로 구분된 계층적 P2PSIP네트워크에서 프록시 서버의 역할을 하는 슈퍼노드를 이용한 효과적인 캐싱 방법을 이용하여 호 설정 지연을 단축할 수 있는 방안을 제안하다.

• IT SoC Magazine
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• s.19
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• pp.37-42
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• 2007

이 글은 당사에서 개발 진행한 TDMB,ISDB-T등의 Moblie TV Receiver단의 Analog Front-End SIP들의 Test H/W, S/W제작 경험을 바탕으로 보다 효율적이고 성공적인 SIP 개발이 될 수 있도록 도움을 주고자 기술 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.659-669
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• 2010

The P2P IPTV will create a new paradigm for the Internet services. However, it cannot guarantee the reliability of their server and QoS because of using common Internet users(peers) for SIP server or relay server, though the infrastructural cost is low. This paper proposes the ISP-based P2P IPTV architecture which can solute the limitations of conventional P2P-based IPTV. In this model, ISP can build P2P overlay network with ISP servers and directly manage each server needed for session connection. So, the servers have higher performance and better reliability than previous one. Besides, robustness is improved because each sever is set by P2P overlay network. To evaluate the characteristics of the ISP-based P2P IPTV architecture, we simulate it for some parameters which are end-to-end streaming delay time, connection delay time and traffic amount. We compared the proposed architecture with the conventional P2P architecture about video service and confirmed that the performance of ISP-based P2P IPTV is better than conventional P2P based IPTV.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.87-92
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• 2008

This paper proposes a session control model for the P2P(Peer to Peer) IPTV(Internet Protocol Television) services and presents the IPTV session control procedures based on the proposed model. Since, while public IPTV traffic is usually processed via a separate network, P2P IPTV traffic is processed together with the conventional Internet access traffic, the P2P IPTV control mechanism needs to provide multi-stream processing for the constituent TPS(Triple Play Service) traffic and corresponding QoS(Quality of Service) control functions. Besides, P2P IPTV session control mechanism should provide appropriate multicast control functions in order to support effective transmission of video traffic generated by personal IPTV broadcasters. The P2P IPTV session control model proposed in this paper is designed to be based on the standard SIP(Session Initiation Protocol), IGMP(Internet Group Management Protocol), and COPS(Common Open Policy Service) protocol so that it can contribute to the easy and prompt deployment of inter-operable P2P IPTV platform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.750-757
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• 2007

This paper analyzes spam threats and proposes key exchange scheme for user authentication and SDP encryption to protect potential spam threats in SIP-based VoIP services. The existing HTTP digest authentication scheme exchanges many message because challenge is sent for every establishment of the session and doesn't provide a confidentiality of SDP. To protect SPIT, our scheme exchanges initial nonce and a session master key for authentication and SDP encryption during registration. In our scheme, the challenge and response procedure is not necessary and the communication overhead is much less than applying S/MIME or TLS.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.579-581
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• 2005

최근 들어 인터넷 사용자가 급증함에 따라 IPv4 주소의 고갈 문제가 대두되었고, 이를 해결하기 위하여 네트워크 주소 변환 기술이 주로 사용되고 있다. 네트워크 주소 변환 기술은 IP 계층에서 주소 변환을 통하여 제한된 IP 주소 자원을 공유해 사용할 수 있는 기술이지만 응용 계층에서 IP 주소를 직접 사용할 경우에 문제가 발생하게 된다. SIP 프로토콜은 다른 프로토콜들에 비하여 구현이 용이하고, 다양한 애플리케이션을 쉽게 개발할 수 있는 장점들을 가지고 있어 차세대 네트워크에서 호 연결을 위한 사실상의 표준으로 자리 잡아가고 있다. SIP 프로토콜을 메시지 라우팅을 위하여 IP 주소를 직접 사용하기 때문에 IP 주소를 응용계층에서 사용할 경우 발생하는 문제를 그대로 안고 있다. 본 논문에서는 SIP 사용자 에이전트가 NAT 환경에서 동작할 때 발생하는 문제점에 대하여 알아보고, NAT 통과를 위해 제시된 표준 기술들에 대하여 알아보고자 한다.