• Journal of Electrical Engineering and information Science
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• v.3 no.1
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• pp.21-27
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• 1998

In this paper we apply routing algorithms in circuit switched networks to B-ISDN networks and investigate the performance. B-ISDN supports a wide range of services with hetrogeneous bandwidth requirements. We assume that the network supports D classes of traffic. It is modeled as a finite D dimensional Markov chain. A call is blocked on arrival if the required bandwidth is not available on the route. The shortest path routing, alternate routing and trunk reservation are considered for performance comparison. We also consider trunk reservation with restricted access control where the network reserves certain amount of bandwidths for one class of traffic that assumes a higher transmission priority. Through the method of successive iterations, we obtain the steady state equilibrium probabilities and call blocking probabilities for dynamic routing. The results can be used to design a B-ISDN network that improves network connection availability and efficiency while simultaneously reducing the network costs.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.115-118
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• 1995

This paper present an attitude control using quaternions as feedback attitude errors. The Euler's eigenaxis rotation provides the shortest angular path between two attitudes. This eigenaxis rotation can be achieved by using quaternions since quaternions are related with the eigenaxis. The suggested controller uses error quaternions and body angular rates and generates a decoupling control torque that counteracts the natural gyroscopic coupling torque. The momentum dumping strategy using the earth magnetic field is also applied in this paper to unload the angular momentum of the reaction wheels used in the attitude control.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.419-422
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• 2005

본 논문은 미지의 공간 그래프에 대한 실시간 최단 경로 탐색 알고리즘인 $RTA{\ast}$ 알고리즘과 $PHA{\ast}$ 알고리즘을 소개하고, 예제 그래프를 통해 이들의 특성을 설명한다. 또 3차원 온라인 게임 환경인 언리얼 토너먼트(Unreal Tournament) 게임과 Gamebots 시스템을 이용하여 두 알고리즘 간의 탐색 최적성과 효율성을 비교하였다. 이 실험을 통하여 $PHA{\ast}$ 알고리즘은 언제나 최선의 경로를 탐색하지만 이동경로가 많고, 시간이 많이 걸릴 수 있으며, $RTA{\ast}$는 최적의 경로 혹은 차선 경로를 빠른 시간 내에 탐색함을 확인 하였다. 따라서 이러한 특성을 바탕으로 주어진 탐색 환경의 조건에 따라 두 알고리즘을 선택적으로 적용함으로써 보다 높은 효과를 얻을 수 것으로 기대한다.

• Journal of Communications and Networks
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• v.9 no.1
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• pp.84-92
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• 2007

This paper deals with the creation of multicast trees in a differentiated services (DiffServ) domain. Initially, we model the integration problems of multicast & DiffServ and give a general de-scription of our framework for multicast provisioning in DiffServ domains. Within this framework, we introduce a novel heuristic algorithm which calculates the multicast trees efficiently. The multicast tree's format and the bandwidth constraints per service class are modeled. The heuristic is based on the Dijkstra's shortest path algorithm and aims to produce the cheapest possible trees (Steiner tree problem) that conform to the defined model. The produced trees can be considered as DiffServ-customized Steiner trees. Furthermore, we evaluate the algorithm with theoretical and experimental analysis and finally, we present our conclusions.

• Journal of Korean Society of Rural Planning
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• v.6 no.2 s.12
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• pp.12-19
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• 2000

Irrigation pipeline networks consist mainly of buried pipes and are therefore relatively free from topographic constraints. Installation of irrigation pipeline systems is increasing since the systems have several advantages compared to open channel systems. To achieve economic design of pipeline networks, the layout should meet several conditions such as shortest path, maximum flow, and least cost. Graph theory is mathematical tool which enable to find out optimum layout for complicated network systems. In this study, applicability of graph theory to figure out optimum layout of irrigation pipeline networks was evaluated.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.184-186
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• 2005

최근 모바일 기기의 성능이 발전함에 따라 다양한 상용 서비스들이 제공되고 있는데 특히 GIS를 이용한 검색 서비스나 차량용 네비게이션 시스템이 대표적이다. 본 논문에서는 GIS서버의 전반적인 시스템 구조와 최단 거리 관리자의 설계 및 구현, 서버 및 PDA기반의 클라이언트 사용자 인터페이스 등에 대해서 소개를 하고자 한다. 최단 경로 관리자는 클라이언트에서 질의 시 목적지까지 최단 거리를 구하여 질의 관리자에 결과를 넘겨주는 역할을 한다. 클라이언트 사용자 인터페이스 부분은 사용자가 쉽게 질의를 작성할 수 있도록 구현 하였다.

• Journal of the Korea Society of Computer and Information
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• v.21 no.2
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• pp.51-60
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• 2016

This paper proposes a hierarchical routing algorithm for enhancing survivability of sensor nodes on WSAN. Proposed algorithm has two important parts. The first is a clustering algorithm that uses distance between sensor and actor, and remaining energy of sensor nodes for selecting cluster head. It will induce uniform energy consumption, and this has a beneficial effect on network lifetime. The second is an enhanced routing algorithm that uses the shortest path tree. The energy efficient routing is very important in WSAN which has energy limitation. As a result, proposed algorithm extends network and nodes lifetime through consuming energy efficiently. Simulation results show that the proposed clustering algorithm outperforms conventional routing algorithms such as VDSPT in terms of node and network life time, delay, fairness, and data transmission ratio to BS.

• Journal of Korea Multimedia Society
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• v.22 no.2
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• pp.210-224
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• 2019

Given a positive integer k as input, a spatial preference query finds the k best data objects based on the scores (e.g., qualities) of feature objects in their spatial neighborhoods. Several solutions have been proposed for spatial preference queries in Euclidean space. A few algorithms study spatial preference queries in undirected spatial networks where each edge is undirected and the distance between two points is the length of the shortest path connecting them. However, spatial preference queries have not been thoroughly investigated in directed spatial networks where each edge has a particular orientation that makes the distance between two points noncommutative. Therefore, in this study, we present a new method called ALPS+ for processing spatial preference queries in directed spatial networks. We conduct extensive experiments with different setups to demonstrate the superiority of ALPS+ over conventional solutions.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.75-83
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• 1999

recently, a new hypercube-like interconnection network, the Z-cube, was proposed. The Z-cube retains most good topological properties, however, its node degree is 3/4 of hypercube's one. Considering hardware implementations, the Z-cube is a good alternative to the hypercube. In this paper, we obtained the diameter, fault diameter and the average distance between two nodes to evaluate the communication performance of the Z-cube. The recursive structure, the shortest path between two nodes I Z-cube and recurrence relation on the average distance were deduced, and node disjoint path was introduced. Although it is generally expected that the communication performance in an interconnection network with reduced node degree falls as much as that, this paper shows that the Z-cube's diameter is the same as the hypercube's one and the average distance between two nodes in Z-cube is about 1.125 times the average distance between two nodes in the hypercube and the fault diameter of Z-cube ranges approximately from 1.4times to 1.7times the fault diameter of the hypercube.

• Journal of information and communication convergence engineering
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• v.8 no.2
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• pp.145-149
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• 2010

In this paper, we propose a kinematic approach to estimating the real-time moving object. A new scheme for a mobile robot to track and capture a moving object using images of a camera is proposed. The moving object is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the active camera. Uncertainties in the position estimation caused by the point-object assumption are compensated using the Kalman filter. To generate the shortest time path to capture the moving object, the linear and angular velocities are estimated and utilized. The experimental results of tracking and capturing of the target object with the mobile robot are presented.