• 전자공학회논문지T
• /
• 제35T권2호
• /
• pp.81-85
• /
• 1998

이동통신망에서 이동국이 등록지역을 이동할 때마다 위치등록 및 위치등록취소가 요구된다. 이동국이 등록지역을 벗어날 때 등록을 취소시키는 몇가지 방법을 조사한 후 등록취소로 인하여 부가되는 통신망의 트래픽을 제거할 수 있는 등록취소 방법을 선택하였다. 그러나 이 기법은 유효한 등록 기록을 삭제시킬 수 있으므로 위치등록 데이타베이스의 크기는 유효한 등록기록이 삭제되는 확률이 낮도록 충분히 크게 해야 한다. 본 논문은 이러한 등록취소 기법에서 위치등록을 위한 데이타베이스 크기를 결정하는 분석 모델을 설명하였다. 분석 모델의 모의실험 결과 데이타베이스의 크기는 위치등록지역에 예상되는 이동국의 수에 비해 3-5배 정도가 되어야 하는 것을 알 수 있었다.

• 한국정보시스템학회지:정보시스템연구
• /
• 제14권3호
• /
• pp.17-22
• /
• 2005

Location management is very important in location-based services to provide services to the mobile users like banking, city guides and many more. Ubiquitous and mobile devices are the source of data in location management and its significant operations are update and search method. Some studies to improve these were presented by using optimal sequential paging, location area scheme and hierarchical database scheme. In addition, not all location services have the same access methods on data and it lead to difficulties of providing services. A proposed location management of multi-agent architecture is presented in this study. It shows the coordination of the agents on the distributed database of location-based services. The proposal focuses on the location management of the mobile object presented in a hierarchical search and update. Also, it uses a nearest neighbor technique for efficient search method of mobile objects.

• Journal of Computing Science and Engineering
• /
• 제4권2호
• /
• pp.173-187
• /
• 2010

Recent technological advances in mobile communication systems have made explosive growth in the number of mobile device users worldwide. One of the most important issues in designing a mobile computing system is location management of users. The hierarchical systems had been proposed to solve the scalability problem in location management. The scalability problem occurs when there are too many users for a mobile system to handle, as the system is likely to react slow or even get down due to late updates of the location databases. In this paper, we propose a top-down clustering algorithm for hierarchical location database systems in a wireless network. A hierarchical location database system employs a tree structure. The proposed algorithm uses a top-down approach and utilizes the number of visits to each cell made by the users along with the movement information between a pair of adjacent cells. We then present a modified algorithm by incorporating the exhaustive method when there remain a few levels of the tree to be processed. We also propose a capacity constraint top-down clustering algorithm for more realistic environments where a database has a capacity limit. By the capacity of a database we mean the maximum number of mobile device users in the cells that can be handled by the database. This algorithm reduces a number of databases used for the system and improves the update performance. The experimental results show that the proposed, top-down, modified top-down, and capacity constraint top-down clustering algorithms reduce the update cost by 17.0%, 18.0%, 24.1%, the update time by about 43.0%, 39.0%, 42.3%, respectively. The capacity constraint algorithm reduces the average number of databases used for the system by 23.9% over other algorithms.

• 반도체디스플레이기술학회지
• /
• 제18권4호
• /
• pp.57-61
• /
• 2019

Nowadays, portable digital cameras such as smart phone cameras are being popularly used for entertainment and visual information recording. Given a database of geo-tagged images, a visual location recognition system can determine the place depicted in a query photo. One of the most common visual location recognition approaches is the bag-of-words method where local image features are clustered into visual words. In this paper, we propose a new bag-of-words-based visual location recognition algorithm using time-series streetview database. The proposed algorithm selects only a small subset of image features which will be used in image retrieval process. By reducing the number of features to be used, the proposed algorithm can reduce the memory requirement of the image database and accelerate the retrieval process.

• 한국사이버테러정보전학회:학술대회논문집
• /
• 한국사이버테러정보전학회 2004년도 제1회 춘계학술발표대회
• /
• pp.103-108
• /
• 2004

현재 HLR system은 이동전화 망에서 지속적으로 변하는 개별 가입자의 위치 정보를 관리 한다. 이를 수행하기 위해, HLR database system은 table 관리 기능과 색인 관리 기능, 그리고 백업 관리 기능을 제공한다. 본 논문에서는, 이동 전화 번호를 위한 적절한 색인 기법으로서 이단계 색인 기법의 사용과, 단말번호를 위한 버켓 연결 해슁 기법을 제안한다. 이동 전화 번호(MDN)와 단말번호(ESN)는 HLR database system에서 key로 사용된다. 또한 HLR database transaction의 특성을 고려한 효율적인 백업 방법을 제안한다. 이단계 색인 기법은 기존의 T 트리 색인 기법보다 검색 속도와 기억 공간 사용 효율 측면에서 우수하다. 버켓 연결 해슁 기법은 기존의 변형된 선형 해슁 기법보다 삽입과 삭제 시의 오버헤드가 적다. 제안한 백업 방법에서는, 빈번한 위치 등록 기능 수행으로 인해 야기되는 성능 저하 문제를 해결하기 위해 두가지 종류의 갱신 플래그를 사용하였다. 아울러 위치 정보의 보안성 처리를 위한 HLR 데이터베이스 Scheme을 제안하였다.

• International journal of advanced smart convergence
• /
• 제7권3호
• /
• pp.61-65
• /
• 2018

A Location Register(LR) system manages each subscriber's location information, which continuously changes in mobile cellular network. For this purpose, the LR database system provides backup management facilities. The objectives of this paper are to identify the problems of the current LR system through rigorous analysis, to suggest solutions to them. I proposed efficient backup methods that takes into account the characteristics of LR database transactions. In the proposed backup method, I use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration- location operations.

• Journal of Information Processing Systems
• /
• 제12권2호
• /
• pp.263-274
• /
• 2016

The exceptional development of electronic device technology, the miniaturization of mobile devices, and the development of telecommunication technology has made it possible to monitor human biometric data anywhere and anytime by using different types of wearable or embedded sensors. In daily life, mobile devices can collect wireless body area network (WBAN) data, and the co-collected location data is also important for disease analysis. In order to efficiently analyze WBAN data, including location information and support medical analysis services, we propose a geohash-based spatial index method for a location-aware WBAN data monitoring system on the NoSQL database system, which uses an R-tree-based global tree to organize the real-time location data of a patient and a B-tree-based local tree to manage historical data. This type of spatial index method is a support cloud-based location-aware WBAN data monitoring system. In order to evaluate the proposed method, we built a system that can support a JavaScript Object Notation (JSON) and Binary JSON (BSON) document data on mobile gateway devices. The proposed spatial index method can efficiently process location-based queries for medical signal monitoring. In order to evaluate our index method, we simulated a small system on MongoDB with our proposed index method, which is a document-based NoSQL database system, and evaluated its performance.

• Journal of the Korean Data and Information Science Society
• /
• 제19권3호
• /
• pp.979-994
• /
• 2008

Moving objects are spatio-temporal data that change their location or shape continuously over time. Generally, if continuously moving objects are managed by a conventional database management system, the system cannot properly process the past and future location which is not stored in the database. Up to now, for the purpose of location tracking which is not stored, the linear interpolation to estimate the past location has been usually used. It is suitable for the moving objects on linear route, not curved route. In this paper, we propose a past location tracking algorithm for a moving object on curved routes, and also suggest a future location tracking algorithm using some past location information. We found that the proposed location tracking algorithm has higher accuracy than the linear interpolation function.

• 대한임베디드공학회논문지
• /
• 제7권2호
• /
• pp.85-93
• /
• 2012

In this paper, we proposed Wireless LAN (WLAN) localization method that enhances database construction based on weighting factor and analyse the characteristic of the WLAN received signals. The weighting factor plays a key role as it determines the importance of Received Signal Strength Indication (RSSI) value from number of received signals (frequency). The fingerprint method is the most widely used method in WLAN-based positioning methods because it has high location accuracy compare to other indoor positioning methods. The fingerprint method has different location accuracies which depend on training phase and positioning phase. In training phase, intensity of RSSI is measured under the various. Conventional systems adapt average of RSSI samples in a database construction, which is not quite accurate due to variety of RSSI samples. In this paper, we analyse WLAN RSSI characteristic from anechoic chamber test, and analyze the causes of various distributions of RSSI and its influence on location accuracy in indoor environments. In addition, we proposed enhanced weighting factor algorithm for accurate database construction and compare location accuracy of proposed algorithm with conventional algorithm by computer simulations and tests.

• 한국디지털정책학회:학술대회논문집
• /
• 한국디지털정책학회 2004년도 International Conference on Digital Policy & Management
• /
• pp.185-202
• /
• 2004

Recent development in wireless computing and GPS technology cause the active development in the application system of location information in real-time environment such as transportation vehicle management, air traffic control and location based system. Especially, study about vehicle location tracking system, which monitors the vehicle's position in a control center, is appeared to be a representative application system. However, the current vehicle location tracking system can not provide vehicle position information that is not stored in a database at a specific time to users. We designed a vehicle location tracking system that could track vehicle location using mobile interface such as PDA. The proposed system consist of a vehicle location retrieving server and a mobile interface. It is provide not only the moving vehicle's current location but also the position at a past and future time which is not stored in database for users.