• Journal of KIISE:Databases
• /
• v.37 no.3
• /
• pp.137-145
• /
• 2010

Wireless sensors play important roles in various areas as ubiquitous computing is generalized. Depending on applications properties, each sensor can be equipped with limited computing power in addition to general function of gathering environment-related information. One of main issues in this environment is to improve energy-efficiency in sensor nodes. In this paper, we devise a new attribute-query processing algorithm. Each sensor has to maintain partial information locally about attributes values gathered at its all descendent nodes. As the volume is higher, however, the maintenance cost also increases. And the update cost also has to be considered in the proposed algorithm. Thus, some bits, AVB(Attribute-Value Bits), are delivered instead of the value itself, where each bit represents a bound of attribute. Thus, the partial information can decrease the number of exchanged messages with a little cost during query processing. Through simulation works, the proposed algorithm is analyzed from several points of view.

• The KIPS Transactions:PartC
• /
• v.18C no.5
• /
• pp.361-368
• /
• 2011

In this study, we present a method for efficiently aggregating networks state information required to determine feasible paths in transport networks that uses the source routing algorithm for hierarchical QoS routing. It is proposed to transform the full mesh topology whose Service Boundary Line serves as its logical link into the star topology. This is an aggregation method that can be used when there are two or more QoS parameters for the link to be aggregated in an asymmetric network, and it improves the information accuracy of the star topology. For this purpose, the Service Boundary Line's 3 attributes, splitting, joining and integrating, are defined in this study, and they are used to present a topology transformation method. The proposed method is similar to space complexity and time complexity of other known techniques. But simulation results showed that aggregated information accuracy and query response accuracy is more highly than that of other known method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.6A
• /
• pp.585-593
• /
• 2010

Geographic routing has been considered as an efficient, simple, and scalable routing protocol for wireless sensor networks since it exploits pure local location information instead of global topology information to route data packets. Geographic routing requires the sources nodes to be aware of the location of sinks. Most existing geographic routing protocols merely assume that source nodes are aware of the locations of sinks. How can source nodes get the locations of sinks was not addressed in detail. In this paper, we propose a sink location service via circle path for geographic routing in wireless sensor networks. In this scheme, a sink sends a Sink Location Announcement (SLA) message along a circle path, and a source node sends a Sink Location Query (SLQ) message along a straight path that certainly passes through the circle path. By this way we can guarantee the SLQ path and SLA path have at least one crossing point. The node located on the crossing point of the two paths informs the source node the sink location. This procedure can correctly work in any irregular profile sensor networks such as network that has holes or irregular shape by some rules. Simulation results show that our protocol is superior to other protocols in terms of energy consumption and control overhead.

• Spatial Information Research
• /
• v.19 no.5
• /
• pp.63-74
• /
• 2011

Recently, there has been much interest in the spatial query which energy-efficiently acquires sensor readings from sensor nodes inside specified geographical area of interests. The centralized approach which performs the spatial query at a server after acquiring all sensor readings, though simple, it incurs high wireless transmission cost in accessing all sensor nodes. In order to remove the high wireless transmission cost, various in-network spatial indexing schemes have been proposed. They have focused on reducing the transmission cost by performing distributed spatial filtering on sensor nodes. However, these in-network spatial indexing schemes have a problem which cannot optimize both the spatial filtering and the wireless routing among sensor nodes, because these schemes have been developed by simply applying the existing spatial indexing schemes into the in-network environment. Therefore, we propose a new distributed spatial indexing scheme of the GR-tree. The GR-tree which form s a MBR-based tree structure, can reduce the wireless transmission cost by optimizing both the efficient spatial filtering and the wireless routing. Finally, we compare the existing spatial indexing scheme through extensive experiments and clarify our approach's distinguished features.

• Journal of KIISE:Databases
• /
• v.35 no.1
• /
• pp.1-16
• /
• 2008

Join queries having heavy cost are necessary to Data Stream Management System in Sensor Network where plural short information is generated. It is reasonable that each join operator has a sliding-window constraint for preventing DISK I/O because the data stream represents the infinite size of data. In addition, the join operator should be able to take multiple inputs for overall results. It is possible for the MJoin operator with sliding-windows to do so. In this paper, we consider the data stream environment where multiple MJoin operators are registered and propose MMJoin which deals with issues of building and processing a globally shared query considering characteristics of the MJoin operator with sliding-windows. First, we propose a solution of building the global shared query execution plan. Second, we solved the problems of updating a window size and routing for a join result. Our study can be utilized as a fundamental research for an optimization technique for multiple continuous joins in the data stream environment.

• Journal of Communications and Networks
• /
• v.17 no.1
• /
• pp.40-46
• /
• 2015

In a mobile ad hoc network (MANET), communication between mobile nodes occurs without centralized control. In this environment the mobility of a node is unpredictable; this is considered as a characteristic of wireless networks. Because of faulty or malicious nodes, the network is vulnerable to routing misbehavior. The resource constrained characteristics of MANETs leads to increased query delay at the time of data access. In this paper, AntHocNet+ Security (ANTSEC) framework is proposed that includes an enhanced cooperative caching scheme embedded with artificial immune system. This framework improves security by injecting immunity into the data packets, improves the packet delivery ratio and reduces end-to-end delay using cross layer design. The issues of node failure and node malfunction are addressed in the cache management.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2003.05b
• /
• pp.1145-1148
• /
• 2003

본 논문에서는 Ad-hoc 망의 멀티캐스트 라우팅 프로토콜인 ODMRP(On-Demand Multicast Routing Protocol)에서 효율적인 유니캐스트 라우팅 프로토콜을 제안한다. ODMRP는 네트워크 상에서 멀티캐스트그룹의 송신원으로부터 수신원에 이르는 경로상에 있는 노드들을 Fe(Forwarding Group) 노드로 선출하여 이들이 해당 멀티 캐스트그룹에 속하는 패킷을 플러딩 하도록 함으로써 데이터를 전송하는 방안이다. 이러한 ODMRP에서는 어느 한 노드가 유니캐스트 모드로(end-to end) 데이터를 전송해야 하는 경우 경로를 찾기 위해 주기적인 플러딩 과정을 거쳐야 하고 이로 인해 오버헤드가 발생하게 된다. 본 논문에서는 이 문제점을 해결하고자 유니캐스트 모드에서 송신원에서 찾은 경로를 DR 라우팅 테이블에 저장해두고 데이터를 보련 때 DR 라우팅 테이블의 정보를 참조함으로써 수신원에서의 불필요한 컨트롤 패킷(JOIN QUERY, JOIN REPLY)으로 인한 트래픽을 줄일 수 있는 방안을 제안한다. 또한 제안된 방식이 기존의 ODMRP 방식보다 데이터의 전송 시간과 경로를 찾는 시간에 있어 개선되었음을 시뮬레이션을 통해 입증한다.

• Journal of the Korean Data and Information Science Society
• /
• v.18 no.1
• /
• pp.161-174
• /
• 2007

In this paper, we propose a high performance database cluster system called HyperDB to process OLAP queries efficiently. HyperDB is a virtual database system running on top of internet-connected PCs; the PCs are used for their own purpose at ordinary times, but they are able to participate in the database cluster system at non-office hours. We propose fully logical replication technique and optimal parallel intra-query routing technique for extensibility and performance. Experiment for TPC-R benchmark shows significant performance upgrade compared with conventional approaches.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.31 no.2
• /
• pp.61-70
• /
• 2008

This paper describes case studies on workflow impact analyze with an enterprise ontology (EO). We build the EO with an ontology editor $Prot{\acute{e}}g{\acute{e}}$ and integrate concepts of enterprise architecture and a process model into it to expand the EO. We use the expanded EO and Prolog query rules to analysis workflow dependency relations from the perspectives of routing, data and role. Through this, we analyze impact of changes in workflow process. Moreover, we have found the effectiveness of the EO and $Prot{\acute{e}}g{\acute{e}}$ in modeling business management and, in particular, workflow representation and management.

• The KIPS Transactions:PartD
• /
• v.12D no.2 s.98
• /
• pp.233-246
• /
• 2005

To enhance the user response time of content-based retrieval service for multimedia information, several multi-dimensional index schemes have been proposed. M-tree, a well-known multidimensional index scheme is of metric space access method, and is based on the distance between objects in the metric space. However, since the overlap between index spaces of nodes might enlarge the number of nodes of M-tree accessed for query processing, the user response time for content-based multimedia information retrieval grows longer. In this paper, we propose a node split algorithm which is able to reduce the sire of overlap between index spaces of nodes in M-tree. In the proposed scheme, we choose a virtual center point as the routing object and entry redistribution as the postprocessing after node split in order to reduce the radius of index space of a node, and finally in order to reduce the overlap between the index spaces of routing nodes. From the experimental results, we can see the proposed split algorithm reduce the overlap between index space of nodes and finally enhance the user response time for similarity-based query processing.