• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.34-36
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• 2006

데이타 중심 저장 방식의 센서 네트워크는 비슷한 값의 데이타를 같은 센서 노드에 저장한다. 따라서 센서 네트워크가 확장되고 비슷한 값의 데이타가 빈번히 발생 시 하나의 센서 노드에 저장이 집중되는 문제가 있다. 기존의 데이타 중심 저장 방식에서 센서 데이타 저장 기법들은 저장 데이타의 효율적인 관리에만 치우쳐 센서 네트워크의 확장 시 하나의 센서 노드에 저장이 집중되는 문제점을 고려하지 않았다. 본 논문은 센서 네트워크의 확장 시 다차원 센서 데이타 저장의 효율적인 scalability를 지원하는 비균등 분할 기법을 제안한다. 제안한 기법은 센서 네트워크를 센서 노드의 분포에 따라 같은 센서 노드 개수를 갖는 영역으로 분할하고 분할된 각 영역 내에서 측정된 센서 데이타를 해당 영역에서 저장 및 관리함으로써 센서 네트워크의 확장에 따른 저장 비용을 줄였다. 그리고, 생성한 영역 개수를 센서 네트워크의 크기와 센서 노드의 개수, 발생하는 데이타의 양에 따라 증가시킴으로서 전체 센서 노드의 에너지 소모가 분산되어 기존의 방식과 비교하였을 때 센서 네트워크의 수명과 scalability가 향상되었다.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.103-113
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• 2008

Vast amount of XML documents raise interests in how they will be used and how far their usage can be expanded, This paper has two central goals: 1) easy and fast retrieval of XML documents or relevant elements; and 2) efficient and stable management of large-size XML documents, The keys to develop such a practical system are how to segment a large XML document to smaller fragments and how to store them. In order to achieve these goals, we designed SCOF(Service-centric Object Fragmentation) model, which is a semi-decomposition method based on conversion rules provided by XML database managers. Keyword-based search using SCOF model then retrieves the specific elements or attributes of XML documents, just as typical XML query language does. Even though this approach needs the wisdom of managers in XML document collection, SCOF model makes it efficient both retrieval and management of massive XML documents.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.52-54
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• 2006

최근 데이타 중심 저장 방식의 센서 네트워크에서 다차원 범위 질의를 위한 인덱스들이 제시되고 있다. 기존에 제시된 다차원 범위 질의 인덱스는 일반적으로 다차원 속성 도메인과 센서 노드의 공간 도메인을 직접 매핑하여 데이타를 관리하는 구조로 되어있다. 그러나, 이러한 구조는 센서 노드의 공간 도메인을 정적으로 분할하기 때문에 센서 노드를 포함하지 않는 영역이 생성되어 데이타 저장 및 질의 처리에서 불필요한 통신이 발생하는 문제가 있다. 본 논문은 이러한 문제를 해결하기 위해 센서 노드의 공간 도메인이 센서 노드를 포함하도록 센서 네트워크 영역을 동적으로 분할하는 다차원 범위 질의 인덱스를 제안한다. 제안하는 인덱스는 센서 노드의 위치에 따라 센서 네트워크 영역을 동적으로 분할하여 데이타 저장 및 질의 처리시 목적 영역으로의 라우팅 경로를 최적화한다. 그리고, 분할된 영역은 모두 센서 노드를 포함함으로 센서 노드에서 발행하는 저장 부하를 분산시켜 전체 네트워크에서 발생하는 전체 통신비용을 줄인다. 실험 결과 제안한 인덱스는 DIM보다 전체 센서 네트워크와 hotspot의 통신비용에서 각각 최대 35%, 60%의 성능 향상을 보였다.

• Journal of Korea Spatial Information System Society
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• v.8 no.3
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• pp.105-115
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• 2006

A sensor network which uses DCS(Data-Centric Storage) stores the same data into the same sensor node. Thus it has a hot spot problem when the sensor network grows and the same data arise frequently. In the past researches of the sensor network using DCS, the hot spot problem caused by growing the sensor network was ignored because they only concentrated on managing stored sensor data efficiently. In this paper, we proposed a non-equal region split method that supports efficient scalability on storing multi-dimensional sensor data. This method can reduce the storing cost, as the sensor network is growing, by dividing whole space into regions which have the same number of sensor nodes according to the distribution of sensor nodes, and storing and managing sensor data within each region. Moreover, this method can distribute the energy consumption of sensor nodes by increasing the number of regions according to the size of the sensor network, the number of sensor nodes within the sensor network, and the quantity of sensor data. Therefore it can help to increase the life time and the scalability of the sensor network.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.595-598
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• 2007

Vast amount of XML documents raise interests in how they will be used and how far their usage can be expanded. This paper has two central goals: 1) easy and fast retrieval of XML documents or relevant elements; and 2) efficient and stable management of large-size XML documents. The keys to develop such a practical system are how to segment a large XML document to smaller fragments and how to store them. In order to achieve these goals, we designed SCOF(Service-centric Object Fragmentation) model, which is a semi-decomposition method based on conversion rules provided by XML database managers. Keyword-based search using SCOF model then retrieves the specific elements or attributes of XML documents, just as typical XML query language does. Even though this approach needs the wisdom of managers in XML document collection, SCOF model makes it efficient both retrieval and management of massive XML documents.

• Journal of KIISE
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• v.43 no.7
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• pp.744-750
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• 2016

Recent cloud infrastructures provide competitive performances and operation costs for many internet services through pay-per-use model. Particularly, object storages are highlighted, as they have unlimited file holding capacity and allow users to access the stored files anytime and anywhere. Several lines of research are based on cloud-backed file systems, which support traditional POSIX interface rather than RESTful APIs via HTTP. However, these existing file systems handle all files with uniform size backing objects. Consequently, the accesses to cloud object storages are likely to be inefficient. In our research, files are profiled according to characteristics, and appropriate backing unit sizes are determined. We experimentally verify that different backing unit sizes for the object storage improve the performance of cloud-backed file systems. In our comparative experiments with S3QL, our prototype cloud-backed file system shows faster performance by 18.6% on average.

• Korean Journal of Remote Sensing
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• v.36 no.5_2
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• pp.867-879
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• 2020

As the era of space technology utilization is approaching, the launch of CAS (Compact Advanced Satellite) 500-1/2 satellites is scheduled during 2021 for acquisition of high-resolution images. Accordingly, the increase of image usability and processing efficiency has been emphasized as key design concepts of the CAS 500-1/2 ground station. In this regard, "CAS 500-1/2 Image Acquisition and Utilization Technology Development" project has been carried out to develop core technologies and processing systems for CAS 500-1/2 data collecting, processing, managing and distributing. In this paper, we introduce the results of the above project. We developed an operation system to generate precision images automatically with GCP (Ground Control Point) chip DB (Database) and DEM (Digital Elevation Model) DB over the entire Korean peninsula. We also developed the system to produce ortho-rectified images indexed to 1:5,000 map grids, and hence set a foundation for ARD (Analysis Ready Data)system. In addition, we linked various application software to the operation system and systematically produce mosaic images, DSM (Digital Surface Model)/DTM (Digital Terrain Model), spatial feature thematic map, and change detection thematic map. The major contribution of the developed system and technologies includes that precision images are to be automatically generated using GCP chip DB for the first time in Korea and the various utilization product technologies incorporated into the operation system of a satellite ground station. The developed operation system has been installed on Korea Land Observation Satellite Information Center of the NGII (National Geographic Information Institute). We expect the system to contribute greatly to the center's work and provide a standard for future ground station systems of earth observation satellites.