• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1843-1850
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• 2004

If the location information of a great number of cars kept for business with telematics terminals is acquired and managed efficiently, this information forms the foundation for controlling cars and traffic flows. The studies on the pure spatial indices have focused on the efficient retrievals. However, the acquisition and management of the terminal location of moving objects are more important than the efficiency of the query processing in the moving object databases. Therefore, it will be need to adopt parallel processing system for the moving object databases which should maintain the object's current location as precise as possible. This paper proposes a location management system using CDMA communications of telematics terminals. More precisely, we propose a architecture of spatial indexing mobile objects using multiple processors, and also newly propose a method of splitting buckets using the properties of moving objects in order to minimize the number of database updates. We also propose a acquisition method for gathering the location information of moving objects and passing the information of the bucket extents in order to reduce the amount of passed messages between processors.

• Journal of KIISE:Databases
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• v.33 no.3
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• pp.271-281
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• 2006

Recently the need for Location-Based Service (LBS) has increased due to the development and widespread use of the mobile devices (e.g., PDAs, cellular phones, labtop computers, GPS, and RFID etc). The core technology of LBS is a moving-objects database that stores and manages the positions of moving objects. To search for information quickly, the database needs to contain an index that supports both real-time position tracking and management of large numbers of updates. As a result, the index requires a structure operating in the main memory for real-time processing and requires a technique to migrate part of the index from the main memory to disk storage (or from disk storage to the main memory) to manage large volumes of data. To satisfy these requirements, this paper suggests a unified index scheme unifying the main memory and the disk as well as migration policies for migrating part of the index from the memory to the disk during a restriction in memory space. Migration policy determines a group of nodes, called the migration subtree, and migrates the group as a unit to reduce disk I/O. This method takes advantage of bulk operations and dynamic clustering. The unified index is created by applying various migration policies. This paper measures and compares the performance of the migration policies using experimental evaluation.

• The Journal of Korean Association of Computer Education
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• v.6 no.4
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• pp.49-59
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• 2003

In order to index exactly moving objects(vehicle, mobile phone, PDA, etc.) in a mobile database, continuous updates of their locations arc inevitable as well as time-consuming. In this paper, we propose a spatial indexing method of moving objects for the efficient mobile map services. In detail, we analyze the characteristics of both the method to re-index all the objects after each time period and the method to update immediately the locations on reporting their locations. We also newly propose a bucket split method using the properties of moving objects in order to minimize the number of database updates. The experiments conducted on the environments of moving object show that the proposed indexing method is appropriate to map services for mobile devices.

• Journal of KIISE:Databases
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• v.33 no.3
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• pp.261-270
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• 2006

Positional data of moving objects can be regularly sampled in order to minimize the cost of data collection in LBS. Since position data which are regularly sampled cannot include the changes of position occurred between sampling periods, sampled position data differ from the data predicted by a time parameterized linear function. Uncertain position data caused by these differences make the accuracy of the range queries for present positions diminish in the TPR tree. In this paper, we propose the uncertainty region to handle the range queries for uncertain position data. The uncertainty region is defined by the position data predicted by the time parameterized linear function and the estimated uncertainty error. We also present the weighted recent uncertainty error policy and the kalman filter policy to estimate the uncertainty error. For performance test, the query processor based by the uncertainty region is implemented in the TPR tree. The experiments show that the Proposed query processing methods are more accurate than the existing method by 15%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.865-870
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• 2005

The latest Global Positioning System, wireless communications technology and Location-Based Service bring about the rapid developments of telematics application areas. In the moving object database for telematics, it is very important to deal with database queries related to the real time current positions of a moving objects and the valid tine of the query results as well. In this paper, we propose how to get not only the current result of query but also the valid time and the result after the valid time when a query point and objects are moving simultaneously. We would like to predict the valid time by formula because the current results will be incorrect due to the characteristic of the continuous movements of the moving objects and the future results can not be calculated by iterative computations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.163-166
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• 2005

The latest wireless communications technology bring about the rapid developments of Global Position System and Location-Based Service. It is very important for the moving object database to deal with database queries related to the trajectories of a moving objects and the valid time of the query results as well. In this paper, we propose how to get not only the current result of query but also the valid time and the result after the time when a query point and objects are moving at the same time. We would like to predict the valid time by formula because the current results will be incorrect due to the characteristic of the continuous movements of the moving objects and the future results can not be calculated by iterative computations.

• Journal of KIISE:Databases
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• v.31 no.1
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• pp.39-47
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• 2004

Spatio-temporal databases have been mostly studied in the area of access methods. However, without considering an extraordinary update maintenance overhead after building up a spatio-temporal index, most indexing techniques have focused on fast query processing only. In this paper, we propose an efficient update management method that reduces the number of disk accesses required in order to apply the updates of moving objects to a spatio-temporal index. We consider realistic update patterns that can represent the movements of objects properly. We present a memory based structure that can efficiently maintain a small number of very frequently updating objects. For an experimental environment with realistic update patterns, the number of disk accesses of our method is about 40% lower than that of a general update method of existing spatio-temporal indexes.

• Journal of Korea Spatial Information System Society
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• v.10 no.3
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• pp.67-78
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• 2008

With the rapid development of wireless communication and mobile equipment, many applications for location-based services have been emerging. Moving objects such as vehicles and ships change their positions over time. Moving objects have their moving path, called the trajectory, because they move continuously. To monitor the trajectory of moving objects in a large scale database system, an efficient Indexing scheme to processed queries related to trajectories is required. In this paper, we focus on the issues of minimizing the dead space of index structures. The Minimum Bounding Boxes (MBBs) of non-leaf nodes in trajectory-preserving indexing schemes have large amounts of dead space since trajectory preservation is achieved at the sacrifice of the spatial locality of trajectories. In this thesis, we propose entry relocating techniques to reduce dead space and overlaps in non-leaf nodes. we present performance studies that compare the proposed index schemes with the TB-tree and the R*-tree under a varying set of spatio-temporal queries.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.1799-1802
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• 2002

이동객체 위치획득시스템은 이동체데이터베이스((MODB : Moving Object Database)에서 위치를 획득하는 서브시스템으로써, 사람 또는 자동차와 같이 이동성을 갖는 객체의 위치를 여러 디바이스를 통해서 획득하는 역할을 한다. 이러한 위치획득시스템은 실시간으로 위치를 획득함에 있어서 통신 부하를 최소화하여야 하며, 획득된 정보의 질을 보장하여야 한다. 또한 다양한 데이터의 집합, 다양한 통신 환경 상황에 대하여 다양한 위치획득 모델을 적용할 수 있어야 하며, 어떠한 상황에서도 통신부하를 최소화하는 것을 목적으로 하고 있다. 정적 위치획득 전략, 거리기반 위치획득 전략, 그룹기반 위치획득 전략, 예측기반 위치획득 전략 등, 다양한 위치획득 전략을 모델링 하여 성능을 보장하여야 한다. 이에 본 논문에서는 이러한 다양한 위치획득 모델을 포함하고 있는 위치획득시스템을 구현하여 그 성능을 평가한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.162-162
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• 2016

비전도체를 피도금체로 하여 전기 도금을 하는 경우 우선 피도금체 상에 시드 층을 형성 시키고 이후 여러 번의 전기도금을 거치게 된다. 이때 접점의 위치와 전류 인가 방법은 도금 특성에 영향을 미치게 된다. 이를 고찰하기 위하여 접점간 거리에 따른 도금 두께 분포 계산을 하였다. 본 연구에서는 도금 분포 계산을 위해 Elsyca社의 PlatingMaster를 사용하였다. 방향별 도금 두께 분포의 변화를 극명하게 관찰하기 위하여 종횡비 10:1로 음극과 양극 모델링을 하였고 접점의 개수는 1 ~ 3개, 접점의 위치는 10 mm 간격으로 이동하는 것을 변수로 하였다. 피도금체의 시드 층은 니켈 층으로 두께 $0.4{\mu}m$로 설정하고 유산동 도금 용액을 이용하여 용액 데이터베이스 측정하고 반영하였다. 계산을 위한 전류 밀도는 $50mA/cm^2$, 도금시간은 10분으로 모든 모델에서 동일하게 적용하였다. 도금이 성장한 면의 두께를 폭과 길이 방향으로 비교 관찰한 결과 전극간의 거리는 시드 층이 얇을수록 두께 분포에 큰 영향을 미쳤다. 하지만 하지 도금 층의 두께가 충분히 두꺼운 경우 전극간의 거리는 큰 영향을 미치지 않는다.