• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.569-572
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• 2003

The broadband wireless access industry, which provides high-tate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. IEEE Standard 802.16, with its WirelessMAN air interface, set the stage for widespread and effective deployments worldwide. This paper presents an implementation of media access control that can be applied to BWA (Broadband Wireless Access) system. Medium access control (MAC) is a key issue in multi-access networks where a common channel is shared by many users. The designed MAC prototype roughly consists of MAC Hardware and MAC Software. The MAC Hardware part includes timing process, MAC transmission control, MAC reception control, and CRC/HCS process. The MAC Software part includes control of MAC signaling, network interface, and Physical (PHY) control. The designed MAC protocol will be integrated with the PHY of BWA in future and we can test overall system performance of MAC and PHY.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.5
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• pp.1-15
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• 1993

In DQDB networks, the bandwidth can be increased considerably be using the EN(Erasure Node) algorithms and DR(Destination Release) algorithms. However, the important issue in implementing them is using method of extra capacity fairly. To improve it, this paper proposes AEN(Adaptive Erasure Node) algorithm which erasure function is activated by network traffic load. Its functional architecture consists of SESM, RCSM, LMSM in addition to the basic DQDB state machines (DQSM, RQM). The SESM and RCSM state machines are placed in front of the DQSM and RQM state machines in order for the node to take advantage of the newly cleared slots. This paper also presents some simulation results showing the effect of AEN algorithm on access delay, throughput and segment erasing ratio in the single and multiple priority networks. The results show that the AEN algorithm offer the better performance characteristics than existing algorithms under overload conditions.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.556-559
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• 2007

Due to its ease of deployment, low cost, self-configuring and self-healing capabilities, Wireless Mesh Networks (WMNs) have emerged as a key technology to be used in a wide scale applications in personal, local, campus, and metropolitan areas. Security and more specifically privacy is an important issue in this type of multi-hop WMN which has given a little attention in the research community. We focus on privacy compromise of a mesh client in a community mesh network that may lead an attacker to reveal mesh clients identity. his other profiles and gain information about mobility. In this paper. we have presented an authentication mechanism with the aid of blind signature that ensures a mesh client to anonymously authenticate itself with a nearby mesh router and thereby preserve identity privacy We have also presented the security and performance analysis of the proposed scheme.

• Electronics and Telecommunications Trends
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• v.13 no.1 s.49
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• pp.21-28
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• 1998

가입자망 투자비용은 전화망의 접속료를 구성하는 비용 요소 중 가장 중요한 부분이다. 본 논문은 대도시지역의 전화가입자망 구축에 소요되는 투자비용을 추정하고, 이러한 투자비용 산출을 위한 일반적인 비용모델의 개발에 관한 것이다. 서울을 대상지역으로 하여 주요 비용요소들이 정의되었고 선로기술, 지형특성, 가입자 수 등의 연관성이 분석되었다. 연구결과는 다사업자 환경에서 접속료 추정을 위한 비용모델 설계에 활용될 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.715-717
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• 2004

인터넷의 폭발적인 성장으로 인하여 MAN(Metropolitan Area Network)은 기존 음성 트래픽 전송 중심의 SONET/SDH(Synchronous Optical NETwork/Synchronous Digital Hierarchy) 환경에서 데이터 트래픽을 수용 할 수 있는 MSPP(MultiService Provisioning Platform) 환경으로 변해가고 있다. 이러한 네트워크 환경에서 이종 망간의 스위칭 역할을 수행하는 NG-SDH장비는 각 망간의 OAM을 제공하기 위해 OAM(Operation/Administration/Maintenance)신호에 대한 IWF(InterWorking Function) 기능을 필요로 하게 된다. 본 논문은 이종 망간 OAM 기능 제공을 위한 IWF에 대해 분석, 정의하고 이를 기반으로 NG-SDH 장비 블록 내에서 이종망간 OAM 기능을 제공할 OAM 변환기를 설계하였다.

• TTA Journal
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• s.104
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• pp.129-136
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• 2006

TTA는 지난 2월 21일, 프랑스 파리에서 개최된 WiMAX 이사회 회의에서 WiMAX 포럼 공인시험소 자격을 획득하였다. 이런 결과를 바탕으로 TTA는 2006년 9월 Mobile WiMAX 시험장비 도입을 시작으로 시험장비 검증과 모의 인증시험을 거쳐 12월부터 Mobile WiMAX 제품에 대한 WiMAX 포럼 공인 인증시험을 실시할 계획이다. 이에 본 고를 통해 현재 진행 중인 Mobile WiMAX 인증시험 개요 및 동향을 소개하고 자 한다. 1) IEEE802.16-2004 : IEEE Standard for Local and Metropolitan Area Networks-Part16: Air Interface for Fixed Wireless Access Systems

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.388-396
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• 2016

The metropolitan subway network of Seoul has gone through many evolutionary processes in past decades to disperse the floating population and improve the traffic flow. In this study, we analyzed how the structural characteristics and the efficiency of the subway network have changed according to the dynamic evolutionary processes of the metropolitan subway network of Seoul. We have also proposed new measures that can be used to characterize the structural properties of the subway network more practically. It is shown that the global efficiency is about 74%, which is higher than those of subway networks of foreign countries. It should also be considered that passenger flow between stations is even higher, at about 85%. Since the private lines, including line 9, the New Bundang line, the Uijeongbu line, and the Ever line do not release their traffic data since September, 2013, only 5 years of data from September, 2008 to September, 2013 is available. So, in this study we limit the analysis period to these 5 years.

• Journal of the Economic Geographical Society of Korea
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• v.19 no.3
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• pp.423-436
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• 2016

In a densely developed metropolitan area, the subway system is often constructed to address the mobility problems. Subway system was first introduced in Seoul in late 1970s, then Korean metropolitan cities began to adopt the system later. Subway systems not only resolve the mobility problems, but also interact with regional socioeconomic landscape. This study aims to find the association between the subway network and land rent within the subway catchment areas in Gwangju metropolitan city in a spaciotemporal framework. The analysis results indicated that proximity to the subway station and the size of nearest road were positively associated with the land rent. Also from a cluster analysis, it was found that the old and new Central Business Districts as well as stations at peripheral areas had distinctive land rent change characteristics. This empirical analysis indirectly proves the strong association between land rent and urban planning and also the positive relationship between land rent and transportation networks.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.95-104
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• 2018

Using network betweenness centrality we attempt to analyze the characteristics of Seoul metropolitan subway lines. Betweenness centrality highlights the importance of a node as a transfer point between any pairs of nodes. This 'transfer' characteristic is obviously of paramount importance in transit systems. For betweenness centrality, both traditional betweenness centrality measure and weighted betweenness centrality measure which uses monthly passenger flow amount between two stations are used. By comparing traditional and weighted betweenness centrality measures of lines characteristics of passenger flow can be identified. We also investigated factors which affect betweenness centrality. It is the number of passenger who get on or get off that significantly affects betweenness centrality measures. Through correlation analysis of the number of passenger and betweenness centrality, it is found out that Seoul metropolitan subway system is well designed in terms of regional distribution of population. Four measures are proposed which represent the passenger flow characteristics. It is shown they do not follow Power-law distribution, which means passenger flow is relatively evenly distributed among stations. It has been shown that the passenger flow characteristics of subway networks in other foreign cities such as Beijing, Boston and San Franciso do follow power-law distribution, that is, pretty much biased passenger flow traffic characteristics. In this study we have also tried to answer why passenger traffic flow of Seoul metropolitan subway network is more homogeneous compared to that of Beijing.

• The Korean Journal of Archival Studies
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• no.65
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• pp.199-226
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• 2020

It is widely agreed that a documentation strategy that considers the social context of fragmented records is needed for documentation of social memories. This paper examined a new methodology named Seoul Narrative Archiving Policy(S-NAP) which was developed for the documentation of social memories in metropolitan areas. Also, the paper reviewed the applicability of S-NAP through the collection cases of Seoul Metropolitan Archives. The development process of the S-NAP is as follows. First, acquisition topic domains that cover an entire metropolitan region were developed. Next, implementation units(S-NAP) were designed through extensive data analysis that encompasses social, economic, culture, and art areas and reflects outcomes of regional studies. As a result, a total of nine acquisition topic domains, 61 parents S-NAP, and 184 children S-NAP were derived from the aforementioned methodology and methods. Finally, this paper proposed the applicability of S-NAP as archival contents and as a supportive tool for archival activity networks.