• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.377-386
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• 2008

In this paper, a new handover management scheme has been proposed to reduce handover latency and to support fast handover without packet losses, so that it may be applicable to the wireless mobile Internet system such as IPv6-based WiBro system. To minimize the handover latency in processing of movement detection, we propose the handover management scheme which simplifies the handover message exchanging procedure between mobile subscriber station (MSS) and network by integrating layer 2 and layer 3 handovers efficiently based on the layer2 information. To reduce the processing delay from new care-of-address (NCoA) configuration during handover, we propose that NCoA is created, distributed and managed by new access control router (NACR). In addition, in order to minimize the packet transmission delay and eliminate the packet losses, the proposed scheme employs a crossover router (CR) which is upper network located over PACR and NACR and employs the packet buffering for MSS. The simulation study shows that the proposed scheme achieves loss-free packet delivery and low latency in the environment of narrow overlapped cell area or high velocity of the MSS, comparing the performance with the conventional schemes.

• Convergence Security Journal
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• v.8 no.1
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• pp.79-90
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• 2008

Services over SIP protocol are anticipated to be commonly used services in our usual life. Especially, presence is a new feature in SIP-based services and actually entities' presence information has close relationship with privacy of them. Also, the XCAP-based authorization is accepted as a highly probable method to protect privacy of entities in SIP-based services. However, there is no proposed presence service model except IM service and it's hard to find the reference model that shows a way how we can apply XCAP-based authorization method into presence service. In this paper, we proposed new presence service model which is applicable to the VoIP service. We suggested presence service model which is making use of XCAP-based authorization to get protection of privacy in a organized way and the suggested model's each messaging steps were reviewed using concrete examples. Contributions of this work is in the suggestion of privacy-aware presence service using XCAP-based authorization and its verification of its each messaging step.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.349-357
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• 2017

Many Web sites adopt SMS(Short Message Service)-based user authentication when a user loses her password or approves an online payment. In SMS-based authentication, the authentication server sends a text in plaintext to a user's phone, and it allows an attacker who eavesdrops or intercepts the text to impersonate a valid user(victim). We propose a challenge-response scheme to prove to the authentication server that a user is in a certain place at the moment with her smartphone beside her. The proposed scheme generates a response using a challenge by the server, user's current location, and a secret on the user's smartphone all together. Consequently, the scheme is much more secure than SMS-based authentication that simply asks a user to send the same text arrived on her phone back to the server. In addition to entering the response, which substitutes the SMS text, the scheme also requests a user to input a passphrase to get the authentication process started. We believe, however, the additional typing should be tolerable to most users considering the enhanced security level of the scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.92-100
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• 2009

In this paper, we analyze the hardware architecture of Low Density Parity Check (LDPC) decoder using Log Likelihood Ration-Belief Propagation (LLR-BP) decoding algorithm. Various design issues that affect the decoding performance and the hardware complexity are discussed and the tradeoffs between the hardware complexity and the performance are analyzed. The message data for passing error probability is quantized to 7 bits and among them the fractional part is 4 bits. To maintain the decoding performance, the integer and fractional parts for the intrinsic information is 2 bits and 4 bits respectively. We discuss the alternate implementation of $\Psi$(x) function using piecewise linear approximation. Also, we improve the hardware complexity and the decoding time by applying overlapped scheduling.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.77-82
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• 2016

Web developers have had difficulties in using Rich Communication Service-e(RCS-e) on their applications because of complicated protocols and closed interfaces. In order to vitalize the use of RCS-e, we need a RCS Application Program Interface(API) which has simple protocols and can be accessed easily. This paper presents the web-based Open API Framework for the RCS-e presence feature. A system architecture for the framework is defined. Call flows for the presence feature between the framework and other nodes are defined. Also, one of the call flows is illustrated to explain how to convert web-based requests to RCS-e requests. Finally, performance evaluation proves that the framework does not add any loads to the existing network infrastructure.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.115-121
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• 2017

Times New RomanThe utilization of Information and Communication Technologies (ICT) in the smart grid application can construct efficient and reliable electrical grid. IEC 61850 was adopted as the standard for smart grid exchanging the information required in an electric power utility. However, applying technologies like IEC 61850 using Ethernet to the automation of small distribution substation directly may cost more than the value of the small distribution substation itself. IEEE 802.15.4 technology attracts attention in the field of power utility automation because of low installation cost and ease of installation. Studies are conducted, which use IEEE 802.15.4 in less strict D1 small distribution substation. This study applied IEEE 802.15.4 to the small distribution substation and conducted performance evaluation using the actual equipment. This study determined the scope of application of IEEE 802.15.4 by conducting a comparative analysis of the message type in IEC 61850.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.46-52
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• 2008

BGP is an exterior routing protocol which exchanges routing information between ASs in ISP or large networks. It is necessary for the BGP to provide traffic enforcement among ASs, for an End-to-End traffic engineering capability in the Internet. However, traditional BGP-4 is lack of end-to-end traffic engineering capability because the policy-based routing affects the traffic only between directly-connected neighbor ASs. This paper proposes an extended BGP routing algorithm to achieve an End-to-End traffic engineering capability. This new method does not require an additional BGP message type, nor change a structure of existing routing table. It only extended the operation of UPDATE message with AS_PATH attribute, which is well-known mandatory. Simulation shows that the new BGP algorithm improves the packet delay and packet loss without the problem of backward compatibility.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.29-36
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• 2007

IP paging strategy, one of the solutions for derived problems in IP mobility support protocol, reduces the messages and the overheads over the network, since there is not registration procedure when a mobile terminal moves into a new router within the same paging area. However, the fact that the mobile terminals with the previous strategy consume electrical power continuously for paging signal reception obstructs the application of IP paging strategy to the IP-based wireless sensor networks. In this paper, we propose a discontinuous paging reception strategy based on the characteristics of the wireless sensor networks and their mobile terminals. As a result of the mathematical analysis, the proposed strategy significantly reduces the terminals' power consumption. In addition, by setting the relating parameters as appropriate values, the proposed strategy can be switched to the continuous reception strategy, or can be adjusted to limit the terminals' power consumption or paging delay.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.468-473
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• 2006

본 논문은 인간의 마음을 움직이는 감각자극과 그것을 생성해 내는 시스템 구현에 관한 연구이다. 마음을 움직이거나, 어떤 행동을 유발하는 정신작용의 과정에 관여하는 요소들을 밝히고, 그 구조와 효과 등을 알아내는 일이 중요하며, 이러한 연구의 성과물들은 정신작용에 관여하는 요소들을 조작, 변수처리 하여 의도적인 정신작용 감각자극을 만들어 낼 수 있는 시스템 구현을 가능하게 할 수 있다. 인간은 감각자극으로 인지된 정보를 자신의 정신적인 필터를 통해 개념화하게 되는데, 이 시스템은 의식에 직접 관여하거나, 우회하는 감각자극에 대한 것들을 제공 할 수 있도록 인간의 개념화의 과정을 의식하여 시스템의 구조를 구현 했다. 인간의 기억데이터와 비슷하다 할 수 있는 구조적 위치의 소스데이터가 있다. 그리고 이것을 현실의 시공간에서 얻어지는 미적 행위와 자극의 반복을 통해 얻어진 결과로 만들어 내거나, 이러한 미적 결과물을 유저는 커뮤니케이션의 도구로 사용할 수 있다. 이와 같은 것의 시작으로, 우리의 삶 깊숙이 침투해 있는 미디어의 감각자극들을 수동적으로 수용하는 것이 아니라 능동적으로 생산해 내는 것이다. 이런 행위는 자신을 가꾸고 만드는 자기최면적인 도구나, 대상을 갖는 커뮤니케이션의 도구를 만들어내는 연구가 될 수 있다. 자신이 필요로 하는 정신적 바탕을 스스로 만들어가는 도구로써, 자신의 메시지를 대상에게 감동을 통해 전달하는 도구로써, 그 역할을 운운하기에는 시기상조인 감이 있다. 하지만 이 시스템은 이러한 비전을 가지고 개발과 발전을 거듭해 인공감성지능 감각자극 생성과 커뮤니케이션 시스템으로 성장 할 것이다.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.38-46
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• 2010

A stable game managing system is absolutely needed to accept simultaneous interlacing of many users for on- line game system. The proposed P2P on-line game system in this paper is able to get stable and real-time game managing within limited time stamp utilizing through reorganizing peers according to synchronous time which can be avoid congestion on one region, it is possible to synchronize for game nodes within limited time stamp utilizing. Reorganizing M-tree which leads 10 distribute loads. The system manages each region unit, and it is execute no matter how big game sizes are. Thus to ensure such as the problems of expand server and stabilization or message transmission. Also, prove efficiency of the suggested system through the simulation.