• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1135-1144
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• 1999

본 논문에서 우리는 셀룰러 통신 시스템을 위한 위치갱신과 위치질의 비용을 줄일 수 있는 새로운 위치관리 기법을 제안한다. 위치갱신 및 위치질의 비용을 줄이기 위하여, 제안한 위치관리 기법은 사용자 지역성을 사용한다. 사용자 지역성은 이동 지역성과 호 지역성으로 이루어진다. 이동 지역성을 갖는 이동단말들을 위한 위치갱신은 지역 PVLR(Proxy-Visitor Location Register) 갱신에 의해 위치갱신 비용을 줄일 수 있다. 호 지역성을 갖는 이동단말들을 위한 위치질의는 지역 PVLR 질의에 의해 위치질의 비용을 줄일 수 있다. 분석 모델을 통하여, 제안한 기법의 성능 분석과 IS-41 표준과 제안 기법과의 성능을 비교한다. 사용된 비교 척도는 네트워크 비용, 데이타베이스 비용 그리고 호 설정 지연이다. 이들 모든 척도들에 대해서, 제안 기법이 IS-41 표준에서 정의된 위치관리 기법보다 더 좋은 성능을 보인다. 또한 비교 결과는 CMR(Call-to-Mobility Ratio)에 상관없이 제안 기법이 IS-41 기법보다 성능이 좋음을 보여준다. Abstract In this paper, we propose a new location management scheme for cellular communication systems with the goal of reducing both location update and query cost. In order to reduce both location update and query cost, the proposed scheme uses user locality. User locality consists of movement and call locality. For mobile terminals with movement locality, location update cost is reduced by local PVLR(Proxy-Visitor Location Register) update. Location query cost is reduced by local PVLR query for mobile terminals with call locality. Through analytical models, we analyze the performance of the proposed scheme and compare it with that of the IS-41 scheme. The measures of comparison used are the network cost, the database cost, and the call set up delay. For all these measures, the proposed scheme performs better than the location management scheme defined in the IS-41 standard. Result comparison also shows that the our scheme performs better than the IS-41 scheme, regardless of CMR(Call-to-Mobility Ratio).

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.17-22
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• 2013

Impersonation attack, based on vulnerable security of SIP, facilitate a intruder to take malicious actions such as toll fraud and session hijacking. This paper suggests a new technique for a countermeasure. When receiving a register request message, registrar checks whether the value of Form header or the value of Call-ID header is stored in location server or not. If the record containing either of them are stored and periodically updated, we regard that message as impersonation attack and discard it. Since this technique uses the information stored in server instead of adding encryption mechanism for user authentication, it can easily build securer SIP environment.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.18-23
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• 2015

This paper proposes a new protection technique against deregistration attack in SIP. Although it is caused by simple spoofing the REGISTER message of a legitimate SIP UA, its impact is serious. This new protection technique identifies and protects the deregistration attack by removing a binding form the location server after delaying a certain period of time instead of removing the binding immediately after receiving deregistration message. Therefore, this technique makes it possible to establish a secure SIP environment defending the deregistraion attack without any additional overhead such as an encryption or authentication.

• IE interfaces
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• v.22 no.2
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• pp.185-191
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• 2009

In this study, we propose an improved group location tracking scheme (GLS) called integrated GLS (IGLS) which, in addition to the group location registration of the GLS, sends an integrated group registration message to a virtual visitor location register (VVLR) instead of sending an individual group registration message. This integrated procedure of proposed scheme leads registration cost of group registration and group location registration to be reduced significantly. Numerical results demonstrate that our proposed IGLS outperforms conventional GLS and delayed GLS (dGLS). The IGLS can be applied effectively on public transportation systems such as subway, train and bus.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.146-149
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• 2001

In order to provide VoIP service that using SIP on the Internet, users must register their current location to receive call from other cal]or. 13y using REGISTER method, users register his or her SIP URL address and currently contactable addresses to registrar server. The registered addresses are not only SIP URI but also mai]to, http, tel, and so on. In these procedures, we must consider authentication mechanism whether he/she has authority to handle the record or not. In this paper, we will briefly describe authentication mechanism that used in SIP and design of registrar server that support the 3rd party registration.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.10
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• pp.1217-1224
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• 1999

이동 호스트들의 위치 정보를 관리하는 것은 이동 컴퓨터 시스템에서 중요한 문제이다. 이동 호스트가 이동할 때 위치 수정과 위치 탐색간에는 상반관계가 존재한다. 본 논문에서는 위치 서버를 이용한 간단한 quorum 기반 분산 동적 위치 관리 방법을 제안한다. 이 방법에서는 이동 호스트들의 위치 정보가 모든 위치 레지스터가 아닌 위치 레지스터들의 부분집합에서 효율적으로 관리되기 때문에 위치 수정 비용과 위치 탐색 비용이 감소된다. 그리고 위치 레지스터들의 부분집합은 동적으로 변하고, 각 위치 서버의 부하는 이동 호스트에 대한 질의율을 고려하므로 균등해진다. 제안된 알고리즘의 성능은 위치 수정비용과 위치 탐색비용의 전체비용으로 평가되었고, Prakash의 알고리즘과 비교되었다.Abstract Managing location information of mobile hosts is an important issue in mobile computing systems. There is a trade-off between location update and search, when a mobile host moves. This paper proposes a simple quorum-based distributed dynamic location management method using location registers. The cost of location updates and searches is reduced by our method because the location information of mobile hosts is managed efficiently in a subset of location registers instead of in all location registers. In our method, the subset of location registers is dynamically changed, and the load of each location register is balanced by considering query rate for mobile hosts. The performance of proposed algorithm is evaluated in terms of the total cost of a location update and a location search, and is compared with Prakash's algorithm.

• ETRI Journal
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• v.37 no.6
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• pp.1087-1095
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• 2015

Mobility management is important in mobile cellular networks. In this study, we considered an enhanced location-based registration (ELR) method. In the ELR method, even when a mobile phone enters a cell to find that the cell is already on its list (of visited cells) and then updates its main counter, it does not remove any cells from the list (memory space permitting), which gives better performance than the location-based registration (LR) method. However, the location registration cost of the ELR method is still high, and there is a lot of room for improvement with regards to this matter. We now propose an improved version of the ELR method; namely, the improved ELR (iELR). In the iELR method, when a mobile phone enters a cell to find that the cell counter value is less than the main counter value, or when a mobile phone enters a cell to register its location, it updates the main counter and the cell counter values as much as possible to reduce the future need for registrations. We show that our proposed iELR method provides better performance than the ELR method.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.559-562
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• 2004

The methodologies to develop land use plans are divided into two different ways, top-down and bottom-up planning. The bottom-up method is more efficient and effective to detailed land use planning. However, it requires considerable amount of information about the present status of land use. Cadastral information system is one of the best information provider for the planning. Building Register Database shows the type, area, use and location of a building. Both cadastral and Building Register systems apparently contain useful information needed to the physical planning. The study focuses on developing a prototype to provide real time information for detailed physical planning by a federated database system using the two databases.

• Journal of Korean Institute of Industrial Engineers
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• v.38 no.2
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• pp.125-132
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• 2012

In this study, we consider zone-based registration (ZBR). In the ZBR, when a mobile station (MS) enters a new location area (LA), it registers its location. Among various types of ZBR, we focus on two zone-based registration with outgoing call (TZRC) that is an improved version of the two zone-based registration (TZR). In the TZR, an MS can store two LAs that it registers recently not to register when it crosses two LAs stored already. In general, TZR has better performance than single zone-based registration (SZR). However, since the TZR may increase paging cost, TZRC was proposed to decrease paging cost. Mathematical analysis is performed to obtain the exact performance of SZR, TZR, TZRC. From the numerical results for various circumstances, it is shown that TZRC outperforms TZR and SZR in most cases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6A
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• pp.361-370
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• 2003

This paper attempts to improve the existing architecture of location register for location management in Private Network to Network Interface(PNNI)-based wireless ATM networks. Our approach enhances the hierarchical architecture of location registers based on a PNNI hierarchical architecture, which is referred to as the logical hierarchy architecture of location registers. This paper introduces a logical hierarchy architecture for location registers to reduce the cost of their location management. This logical hierarchy architecture of location registers begins with the lowest level physical location registers that are organized into clusters called logical groups. These logical groups are then represented in higher layers by logical nodes. These logical nodes are again grouped into clusters that are treated as single nodes by the next higher layer. In this way, all location registers are included in this tree-type logical hierarchy architecture. Compared with the existing physical hierarchy architecture of location registers, the analysis results show that the proposed logical hierarchy architecture can reduce the number of databases and thereby the average total location management cost.