• Title/Summary/Keyword: Node Search

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A hierarchical routing protocol of suggest to Sensor network reconfiguration (센서 네트워크의 재배치를 고려한 계층적 라우팅 프로토콜)

  • Kwon, Hoon;Kim, Jeong-Hee;Kwak, Ho-Young
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.6
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    • pp.1113-1119
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    • 2008
  • In IP-USN for replacing the sensor network based on Zigbee by IP-based it, routing and the address assignment technique for sensor node are important focuses. But, there is a weak point in existing hierarchical routings. It is that all paths must be searched because the end node isn't considered. And the end node based muting is not sufficient in the mobile sensor network environment because it supports the only simple-path-search. Hereupon, this thesis suggests ComHRP(Complement HRP) that have the only merits of existing methods. The address assignment technique and search method are also proposed. ComHRP simplifies the organization of sensor networks and reduces network complexity. Also, It can efficiently deal with restructuring networks for the unpredictable ubiquitous sensor network feature.

A Location Information-based Gradient Routing Algorithm for Wireless Ad Hoc Networks (무선 애드혹 네트워크를 위한 위치정보 기반 기울기 라우팅 알고리즘)

  • Bang, Min-Young;Lee, Bong-Hwan
    • The KIPS Transactions:PartC
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    • v.17C no.3
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    • pp.259-270
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    • 2010
  • In this paper, a Location Information-based Gradient Routing (LIGR) algorithm is proposed for setting up routing path based on physical location information of sensor nodes in wireless ad-hoc networks. LIGR algorithm reduces the unnecessary data transmission time, route search time, and propagation delay time of packet by determining the transmission direction and search range through the gradient from the source node to sink node using the physical location information. In addition, the low battery nodes are supposed to have the second or third priority in case of forwarding node selection, which reduces the possibility of selecting the low battery nodes. As a result, the low battery node functions as host node rather than router in the wireless sensor networks. The LIGR protocol performed better than the Logical Grid Routing (LGR) protocol in the average receiving rate, delay time, the average residual energy, and the network processing ratio.

An Efficient k-D tree Traversal Algorithm for Ray Tracing on a GPU (GPU상에서 동작하는 Ray Tracing을 위한 효과적인 k-D tree 탐색 알고리즘)

  • Kang, Yoon-Sig;Park, Woo-Chan;Seo, Choong-Won;Yang, Sung-Bong
    • Journal of KIISE:Computer Systems and Theory
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    • v.35 no.3
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    • pp.133-140
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    • 2008
  • This paper proposes an effective k-D tree traversal algorithm for ray tracing on a GPU. The previous k-D tree traverse algorithm based on GPU uses bottom-up searching from a leaf to the root after failing to find the ray intersected primitive in the leaf node. During the bottom-up search the algorithm decides the current node is visited or not from the parent node. In such a way, we need to visit the parent node which was already visited and the duplicated bounding box intersection tests. The new k-D tree traverse algorithm reduces the brother and parent duplicated visit by using an efficient method which decides whether the brother node is already visited or not during the bottom-up search. Also the algorithm take place bounding box intersection tests only for the nodes which is not yet done. As a result our experiment shows the new algorithm is about 30% faster than the previous.

Effect of Node Size on the Performance of the B+-tree on Flash Memory (플래시 메모리 상에서 B+-트리 노드 크기 증가에 따른 성능 평가)

  • Park, Dong-Joo;Choi, Hae-Gi
    • The KIPS Transactions:PartA
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    • v.15A no.6
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    • pp.325-334
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    • 2008
  • Flash memory is widely used as a storage medium for mobile devices such as cell phones, MP3 players, PDA's due to its tiny size, low power consumption and shock resistant characteristics. Additionally, some computer manufacturers try to replace hard-disk drives used in Laptops or personal computers with flash memory. More recently, there are some literatures on developing a flash memory-aware $B^+$-tree index for an efficient key-based search in the flash memory storage system. They focus on minimizing the number of "overwrites" resulting from inserting or deleting a sequence of key values to/from the $B^+$-tree. However, in addition to this factor, the size of a physical page allocated to a node can affect the maintenance cost of the $B^+$-tree. In this paper, with diverse experiments, we compare and analyze the costs of construction and search of the $B^+$-tree and the space requirement on flash memory as the node size increases. We also provide sorting-based or non-sorting-based algorithms to be used when inserting a key value into the node and suggest an header structure of the index node for searching a given key inside it efficiently.

Automatic Extraction of 2-Dimensional Finite Element Connectivities by Search Technique (탐색기법을 이용한 2차원 유한요소 연결관계의 자동추출)

  • 김한수
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.3
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    • pp.329-336
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    • 2000
  • A method for automatic extraction of 2-dimensional finite element connectivities by searching the shortest closed path from a certain node to the starting node was developed. Only the best path among the possible paths was probed. The uniqueness and validity of the extracted path were examined. The proposed method was proved to be complete. Examples show that the proposed method can extract elements exactly from the irregular mesh which can not be handled easily by the conventional automatic mesh generation.

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Fault Diagnosis Using T-invariance of Petri Net (페트리네트의 T-invariance를 이용한 시스템의 고장진단)

  • 정석권;정영미;유삼상
    • Journal of Ocean Engineering and Technology
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    • v.15 no.4
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    • pp.101-107
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    • 2001
  • This paper describes a fault diagnosis method by a T-invariance of Petri Net (PN). First, a complicated fault system with some failure is modeled into a PN graphic expressions. Next, the PN model is analyzed by using the backward chaining of T-invariance to find out causes of the faults. In this step, an inter-node search technique which is suggested in this paper is applied for reducing searching area in the fault system. Also, a novel idea to compose incidence matrices which have different dimension each other in PN model is proposed. As the new knowledges which is discovered newly about faults can be added easily to conventional systems, the diagnosis system will be very flexible. Finally, the proposed method is applied to the automobile fault diagnosis system to confirm the validity of the method.

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Local Map-based Exploration Strategy for Mobile Robots (지역 지도 기반의 이동 로봇 탐사 기법)

  • Ryu, Hyejeong;Chung, Wan Kyun
    • The Journal of Korea Robotics Society
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    • v.8 no.4
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    • pp.256-265
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    • 2013
  • A local map-based exploration algorithm for mobile robots is presented. Segmented frontiers and their relative transformations constitute a tree structure. By the proposed efficient frontier segmentation and a local map management method, a robot can reduce the unknown area and update the local grid map which is assigned to each frontier node. Although this local map-based exploration method uses only local maps and their adjacent node information, mapping completion and efficiency can be greatly improved by merging and updating the frontier nodes. Also, we suggest appropriate graph search exploration methods for corridor and hall environments. The simulation demonstrates that the entire environment can be represented by well-distributed frontier nodes.

Fault Diagnosis Using Backward Chaining of T-invariance (T-invariant의 후방추론 기법을 이용한 시스템의 고장진단)

  • 정영미;정석권;유삼상
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.32-37
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    • 2001
  • This paper describes a noble fault diagnosis method using inter node search technique in PN model. First, a complicated fault system is modeled as PN graphic expressions. Next, to find out sources for faults on which we focus, the PN model is analyzed using the backward chaining of T-invariance. In this step, the technique of inter node search is applied for reducing some range of sources in a fault. Also, colnposing method of incidence matrix in PN is proposed. Then, it makes the diagnosis system to very flelible system because new knowledges about the sources in a fault can be added easily to conventional systems. Finally, the proposed method is applied to the automobile trouble diagnosis system to confirm the validity of the method.

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A Flexible Branch and Bound Method for the Job Shop Scheduling Problem

  • Morikawa, Katsumi;Takahashi, Katsuhiko
    • Industrial Engineering and Management Systems
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    • v.8 no.4
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    • pp.239-246
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    • 2009
  • This paper deals with the makespan minimization problem of job shops. The problem is known as one of hard problems to optimize, and therefore, many heuristic methods have been proposed by many researchers. The aim of this study is also to propose a heuristic scheduling method for the problem. However, the difference between the proposed method and many other heuristics is that the proposed method is based on depth-first branch and bound, and thus it is possible to find an optimal solution at least in principle. To accelerate the search, when a node is judged hopeless in the search tree, the proposed flexible branch and bound method can indicate a higher backtracking node. The unexplored nodes are stored and may be explored later to realize the strict optimization. Two methods are proposed to generate the backtracking point based on the critical path of the current best feasible schedule, and the minimum lower bound for the makespan in the unexplored sub-problems. Schedules are generated based on Giffler and Thompson's active schedule generation algorithm. Acceleration of the search by the flexible branch and bound is confirmed by numerical experiment.

Distributed Search of Swarm Robots Using Tree Structure in Unknown Environment (미지의 환경에서 트리구조를 이용한 군집로봇의 분산 탐색)

  • Lee, Gi Su;Joo, Young Hoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.2
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    • pp.285-292
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    • 2018
  • In this paper, we propose a distributed search of a cluster robot using tree structure in an unknown environment. In the proposed method, the cluster robot divides the unknown environment into 4 regions by using the LRF (Laser Range Finder) sensor information and divides the maximum detection distance into 4 regions, and detects feature points of the obstacle. Also, we define the detected feature points as Voronoi Generators of the Voronoi Diagram and apply the Voronoi diagram. The Voronoi Space, the Voronoi Partition, and the Voronoi Vertex, components of Voronoi, are created. The generated Voronoi partition is the path of the robot. Voronoi vertices are defined as each node and consist of the proposed tree structure. The root of the tree is the starting point, and the node with the least significant bit and no children is the target point. Finally, we demonstrate the superiority of the proposed method through several simulations.