• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.873-879
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• 2013

In this paper, high-quality business-type communications(UC) capabilities of the communication activities overlap, waste, reducing rework process improvement provides for high efficiency. Messages sent via UC app development, FMC calling features, schedule management organization for the development and deployment DataBase UC server deployment, the search for the JSP implementation, XMPP is using the messaging system. IP-PBX running on the IP network, on the basis of UC applications in real life, improve utilization of the infrastructure necessary to provide services to the system design and implementation.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.251-264
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• 2016

The purpose of this study is to compose direction about mUC as a communication channel in the company. Recently, many companies have started to adopt or try to vitalize the use of mUC. This study starts from the viewpoint of communication which is the original purpose of SNS or mUC. The purpose and function of life-world are drawn based on Habermas' theory of communicative action. Firstly, this study will check on a difference in usage over the action and articulation between SNS and mUC. Secondly, this study will examine a difference of effect of life-world between SNS and mUC. Thirdly, to check that there is difference according to the user characteristics. The result is that there are differences about action and articulation but little differences of effect to the life-world between SNS and mUC. Also, there is difference according to the user characteristics. This study could contribute to compose direction when a company adopts or vitalizes mUC.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.714-717
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• 2012

통신기술의 발전으로 사람과 사람의 의사소통에 있어서 IT 기술을 접목시킨 여러 기술들이 발전하고 있다. SIP 기반의 UC 서비스 또한 기업과 고객의 원활한 커뮤니케이션을 위하여 기술이 꾸준히 발전하고 있다. 그러나 UC 서비스 또한 IP 기반의 서비스이기 때문에 여러 가지 보안위협의 노출이 되어 있다. SIP 기반의 서비스는 QoS(Quality of Servic)가 보장되어야 하지만 품질에 중점을 두어 보안위협에 크게 노출 되어 있는 것이 사실이다. 이에 본 논문에서는 SIP 보안 메커니즘인 HTTP Digest 사용자 인증, TLS 홉간 보안, S/MIME을 이용한 단말간의 보안 메커니즘을 적용하고 Virtual Proxy Server를 이용한 보안 시스템을 설계 하였다.

• ETRI Journal
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• v.42 no.5
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• pp.669-685
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• 2020

5G AgiLe and fLexible integration of SaTellite And cellulaR (5G-ALLSTAR) is a Korea-Europe (KR-EU) collaborative project for developing multi-connectivity (MC) technologies that integrate cellular and satellite networks to provide seamless, reliable, and ubiquitous broadband communication services and improve service continuity for 5G and beyond. The main scope of this project entails the prototype development of a millimeter-wave 5G New Radio (NR)-based cellular system, an investigation of the feasibility of an NR-based satellite system and its integration with cellular systems, and a study of spectrum sharing and interference management techniques for MC. This article reviews recent research activities and presents preliminary results and a plan for the proof of concept (PoC) of three representative use cases (UCs) and one joint KR-EU UC. The feasibility of each UC and superiority of the developed technologies will be validated with key performance indicators using corresponding PoC platforms. The final achievements of the project are expected to eventually contribute to the technical evolution of 5G, which will pave the road for next-generation communications.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.3
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• pp.1-10
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• 2011

In this paper, we implemented the Android NDK porting application with Eclipse(JDK) ADT and TinyOS 2.0. TinyOS and Cygwin are component based embedded system and an Open-source basis for interfacing with sensor application from H-mote. Cygwin is a collection of tools for using the Linux environment for commercially released with x86 32 bit and 64 bit versions of Windows. TinyOS-2. x is a component based embedded OS by UC Berkeley and is an Open-source OS designed for interfacing the sensor application with specific C-language. The results of Android porting experiment are described to show the improvement of sensor interfacing functionality under the PXA320 embedded RTOS platform. We will further more develop the software programming of Android porting under Embedded platform and enhance the functionality of the Android SDK with mobile gaming and kernel programming under sensor interfacing activity.

• Journal of KIISE:Information Networking
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• v.36 no.2
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• pp.80-89
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• 2009

A DHT(Distributed Hash Table) based P2P is a method that compensates disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do fast data search and maintain search efficiency independent of the number of peers. The peers in a DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in a DHT method should send messages more frequently to keep the routing table updated and reduce the failure of requests. However this results in increasing the overall network traffic. In this paper, we propose a method to reduce the update load of a routing table in the existing DHT by updating it in a reactive way. In the proposed reactive method, a routing table is updated only if a data request is coming whereas it is updated periodically in the existing proactive method. We perform experiments using Chord simulator(I3) made by UC Berkely. The experimental results show the performance improvement of the proposed method compared to the existing method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2007.02a
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• pp.101-104
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• 2007

Ad hoc 네트워크는 기반구조가 없는 무선네트워크이다. Ad hoc 네트워크는 재난지역, 군사지역, 홈 네트워킹 서비스, 텔레매틱스 서비스 같은 곳에서 응용될 수 있다. 최근Ad hoc 네트워크의 처리량을 향상시키기 위해 방향성 안테나를 사용하거나 이중채널을 사용하는MAC프로토콜이 제안되고 있다. DUBMAC프로토콜은 이중채널에 방향성 안테나를 사용하여 처리량 성능을 향상시킨 프로토콜이다. 본 논문에서는 DUDMAC프로토콜에 전력 제어 기법을 적용하여 네트워크의 처리량을 향상시키는 MAC 프로토콜을 제안한다. 제안하는 MAC 프로토콜은 새로운 블로킹 알고리즘을 사용하여 공간 재사용을 향상시킨다. 제안하는 블로킹 알고리즘은 RTS 또는 CTS 수신 시 블로킹 테이블에 저장된 수신세기를 사용하여 기존의 DUDMAC의 블로킹 영역을 FULL_BLOCKING 영역과 SEMI_BLOCKING 영역으로 구분하여 성능을 개선한다. 제안하는 MAC 프로토콜의 처리량 성능은 퀄넷 시뮬레이터 버전 3.8을 사용하여 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12A
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• pp.1309-1318
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• 2004

The rapid growth of the mobile Internet has enabled its application area to expand, and its users want services that require more bandwidth for multimedia services. There are limits to support the various multimedia service to mobile station provided by existing mobile communications. The wireless MAN called the IEEE 802.16 Broadband Wireless Access systems which the IEEE 802.11 wireless LAN is similar to wireline Internet service being able to supper a various contents is used and is designed to consider a handoff is studying. Especially, TG(Task Group)e of IEEE 802.16 is in progress discussion to support a handoff to higher layer using BS(Base Station) or unit of sector, to UC. Yet a scheme is not detail. This thesis proposes the network model for IEEE 802.16e to support a soft handoff between BSs to use a mobile communication network called cdma2000 Ix EV-DO network. The proposed network model supports soft handoff to add a management skill in MA of each BS for MC(Mobility Controller). The proposed network model has merits that is able to apply existing systems as it is and that is able to use a various multimedia service, when using a wireless Internet.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.773-782
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• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.761-772
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• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.