• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.165-174
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• 2006

Data dissemination using either flooding or legacy ad-hoc routing protocol is not realistic approach in the wireless sensor networks, which are composed of sensor nodes with very weak computing power, small memory and limited battery. In this paper, we propose the ELF(Energy-efficient Localized Flooding) protocol. The ELF is energy-efficient data dissemination protocol for wireless sensor networks. In the ELF protocol, there are two data delivery phases between fixed source and mobile sink node. The first phase, before the tracking zone, sensing data are forwarded by unicasting. After that, within the tracking zone, sensing data are delivered by localized flooding. Namely, the ELF Properly combines advantages from both unicasting and flooding. According to evaluation results by simulation, the proposed ELF protocol maintains very high data delivery ratio with using a little energy. Also, the property of average delay is better than others. From our research results, the ELF is very effective data dissemination protocol for wireless sensor networks.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.276-280
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• 2008

Many dissemination protocols on the mobility support in wireless sensor networks have been designed based on the assumption that the movement trace of sinks, such as soldiers and fire fighters, is random. However, the mobility of the sinks in many applications, for example, the movement trace of a soldier on operation in a battle field, can be determined in advance. In this paper, we propose a Predictable Mobility-based Data Dissemination protocol that enables data to directly route from source nodes to moving sinks by taking into consideration predictable movement behavior of the sinks. We also show the superiority of the predictable mobility-based data dissemination protocol through the performance comparison with the random mobility-based data dissemination protocols.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.316-320
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• 2008

Data dissemination schemes for wireless sensor networks, where sinks and event targets might be mobile, has been one of the active research fields. For doing that, stationary nodes gathered data on behalf of mobile sinks and the relayed data in previous studies. their schemes, however, lead to frequent query flooding and report congestion problems over sink moving. We propose a data dissemination protocol to solve both the query flooding and the report congestion problem. Our scheme improves the two shortcomings through sink location management. Finally, we prove effectiveness of our protocol through computer simulations.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.329-342
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• 2003

Most of the existing multicast routing protocols for ad-hoc networks do not take into account the efficiency of the protocol for the cases when there are large number of sources in the multicast group, resulting in either large overhead or poor data delivery ratio when the number of sources is large. In this paper, we propose a multicast routing protocol for ad-hoc networks, which particularly considers the scalability of the protocol in terms of the number of sources in the multicast groups. The proposed protocol designates a set of sources as the core sources. Each core source is a root of each tree that reaches all the destinations of the multicast group. The union of these trees constitutes the data delivery mesh, and each of the non-core sources finds the nearest core source in order to delegate its data delivery. For the efficient operation of the proposed protocol, it is important to have an appropriate number of core sources. Having too many of the core sources incurs excessive control and data packet overhead, whereas having too little of them results in a vulnerable and overloaded data delivery mesh. The data delivery mesh is optimally reconfigured through the periodic control message flooding from the core sources, whereas the connectivity of the mesh is maintained by a persistent local mesh recovery mechanism. The simulation results show that the proposed protocol achieves an efficient multicast communication with high data delivery ratio and low communication overhead compared with the other existing multicast routing protocols when there are multiple sources in the multicast group.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2150-2164
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• 1997

Two distinct features required in transport service and protocol to meet new multimedia applications requirements are multicast transmission capability and enhanced QoS facility. In this paper, we presents major functions and facilities of enhanced communications transport service definition supporting these requirements. At first, major fundamental issues, that should be handled to design multi-peer communcation service and protocol, are resoved and applied to design service definition. Secondly, we proposed several new functions for enhanced transport service such as heterogeneous TC establishment, invitation capability, TC-ownership transfer, restriction of transmit concurrency. The detils of proposed enhanced transport service are TC creation, TC invitation, TC join, multicase data transfer, pause of data transfer, resulme of data transfer, report of specific status, TC leave, TC termination, TC-ownership transfer, Token transfer services. The proposed transport service was submitted and accepted as a draft text for committee draft of international standard by the international standradization body such as JTC1/SC6 and ITU-T SG 7.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1997.11a
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• pp.161-170
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• 1997

SASC(Server-Aided Secret Computation) 프로토콜은 클라이언트(스마트 카드)의 비밀정보를 공개하지 않으면서 서버(untrusted auxiliary device)에게 서명을 생성하는데 도움을 받도록 하는 프로토콜이다. RSA서명을 위한 최초의 SASC 프로토콜은 RSA-S1 으로서 그 실효성이 크기 때문에, 그 후로 SASC 프로토콜에 대한 연구가 많이 이루어져 왔다. 기존의 SASC 프로토콜들의 공통된 접근방식은, 클라이언트의 비밀정보를 서버로부터 감추기 위해, 비밀정보를 여러 조각으로 나누어 일부불만을 서버에게 전달하는 방식이었다. 그러나, 이러 한 접근방식은 클라이언트의 계산량은 줄어들지만 서버의 계산량과 통신량이 너무 많고, 능동적 공격(active attack)에 노출되기 쉽다는 단점을 가진다. 본 논문에서는 이러한 단점을 극복하기 위해 RSA서명 생성을 위한 새로운 방식의 SASC 프로토콜을 제안한다. 본 논문에서 제안하는 방식은 비밀정보를 서버로부터 감추기 위해 비밀정보에 난수들을 곱하거나 더하여 서버에게 전달하는 방식이다. 제안 프로토콜은 능동적 공격에 대해 안전하며, 안전성이 데이타의 개수에 의존하지 않으므로 서버의 계산량과 통신량이 매우 적다. 또한, 클라이언트가 수행해야 할 계산량도 기존 프로토콜들의 43%로 줄게 된다.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.127-131
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• 2001

휴대용 단말기와 이동통신 기술의 발달로 무선 네트워크의 사용이 급증하면서 호스트가 이동중에도 지속적인 네트워킹이 가능한 프로토콜들이 개발되고 있다. Mobile IP는 이동 노드(mobile node)가 인터넷상의 임의의 다른 위치에 접속하여 IP 주소를 변경하지 않고, 홈 주소를 이용하여 통신하며 위치에 따른 care-of address에 의해 데이타를 터널링하여 전달받는다. 본 논문에서는 컴퓨터 시뮬레이션을 통해 self-similar 트래픽을 갖는 mobile IP의 성능을 분석한다. 일반적으로 데이타 트래픽, 바인딩 갱신시간, 버퍼관리 방법 등은 핸드오프 동안 mobile LP의 성능에 많은 영향을 비친다. 따라서 시뮬레이션 모델을 이용하여 self-similar 트래픽 환경에서 위에 언급된 성능 파라미터들의 영향을 분석한다.

• Journal of KIISE:Information Networking
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• v.29 no.2
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• pp.156-164
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• 2002

IPSec is a protocol which provides data encryption, message authentication and data integrity on public and open network transmission. In IPSec, ESP protocol is used when it needs to provide data encryption, authentication and Integrity In real transmission packets. ESP protocol uses DES-CBC encryption mode when sender encrypts packets and receiver decrypts data through this mode IV is used at that time. This value has many tasks of attack during transmission by attacker because it is transferred clean and opened. If IV value is modified, then decryption of ESP data is impossible and higher level information is changed. In this paper we propose a new algorithm that it encrypts IV values using DES-ECB mode for preventing IV attack and checks integrity of whole ESP data using message authentication function. Therefore, we will protect attacks of IV and data, and guarantee core safe transmission on the public network.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.430-440
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• 2000

To support Integrated Services in the Internet, the Internet Engineering Task Force(IETF) has developed new mechanisms. These new mechanisms include Resource Reservation Protocol(RSVP) and Integrated Services model. RSVP and Integrated Services are independent of the underlying link layer technologies and it is necessary to define the mapping of RSVP and Integrated Services specifications onto specific link layer technologies. IETF proposed a Subnet Bandwidth Manager(SBM) providing a method for mapping RSVP onto IEEE802 style networks. However, the SBM has several constraints and problems. For solving these constraints and problems, we design and implement a new Ethernet Bandwidth Manager(EBM). This paper discusses (1) new bandwidth management mechanism independent of RSVP, (2) simulation of Ethernet bandwidth to analyze the characteristics of Ethernet and accomplish Ethernet bandwidth management, (3) design and implemetation of EBM that allows Controlled-Load Service, and (4) results of our experiments on EBM.

• Proceedings of the Korea Database Society Conference
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• 1995.12a
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• pp.101-108
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• 1995

ATM 통신망에서 멀티미디어/하이퍼미디어 응용 서비스를 제공하기 위한 통신 기능을 분석하고 프로토콜 기능 구조를 제안한다. 멀티미디어 응용 서비스를 효율적으로 제공하기 위해서는 개별 정보 매체 흐름을 각각 지원할 수 있는 다수의 연결을 설정, 유지, 해제할 수 있는 다중연결 관리 기능이 있어야 하며, 하이퍼미디어 정보 구조를 지원하기 위해서는 해당 정보 매체의 흐름을 위한 연결을 동적으로 신속히 추가, 삭제할 수 있어야 한다. 본 논문에서 제시하는 기능 구조에서는 ATM 통신망이 제공하는 광대역 전달 기능 및 통신망 관리, 제어 기능을 충분히 활용하고, 추가적인 기능을 상위 프로토콜로 구현함으로써 효율적인 멀티미디어/하이퍼미디어 응용 서비스 제공이 이루어지도록 한다.