• Journal of the Korea Society of Computer and Information
• /
• v.14 no.7
• /
• pp.97-103
• /
• 2009

This paper proposes efficient routing scheme named MP-DD(MultiPath-Direct Diffusion) which is simple enough to be applicable to the wireless sensor networks. Conventional DD uses only one optimal path, therefore it consumes more energy of specific nodes. MP-DD uses multiple path and has a information of hop upstream node in the direction of the base-station is determined which are obtainable via the process of self-organization of the network. Simulation results show the feasibility of the simple routing schemes for the sensor networks.

• Journal of the Korea Society for Simulation
• /
• v.17 no.2
• /
• pp.91-103
• /
• 2008

In order to simulate the behavior of automated manufacturing systems, the performance of material handling systems should be measured dynamically. Multi-Agent technology could be well adapted for the development of simulator for distributed and intelligent manufacture systems. A multi-agent system is composed of one coordination agent and multiple application agents. Issues in AGVS simulator can be classified by the set-up and operating problems. Decisions on the number of vehicles, bi- or uni-directional guide-path, etc. are fallen into the set-up problem category, while deadlock tree algorithm and conflict resolution are in operating problem. In this paper, a multi-agent based deadlock-free simulator for automated guided vehicle system(AGVS) are proposed through the use of multi-agent technologies and the development of deadlock-free algorithm. In this AGVS simulator proposed, well-known Floyd algorithm is used to create AGVS Guide path, through which AGVS move. Also, AGVs avoid vehicle conflict and deadlock using check path algorithm. And Moving vehicle agents are operated in real-time control by coordination agent. AGV position is dynamically calculated based on the concept of rolling time horizon. Simulator receives and presents operating information of vehicle in AGVS Gaunt chart. The performance of the proposed algorithm and developed simulator based on multi-agent are validated through set of experiments.

• The Journal of Korea Robotics Society
• /
• v.18 no.1
• /
• pp.10-17
• /
• 2023

Recently, robots have been actively utilized for logistics and delivery services in various places such as restaurants, hotels, and hospitals. In addition, it provides a safer environment, convenience, and cost efficiency to the customers. However, when it comes to autonomous delivery in a multi-floor environment, the task is still challenging. Especially for wheeled mobile robots, it is necessary to deal with elevators to perform the last-mile delivery services. Therefore, we present a multi-floor route planning algorithm that enables a wheeled mobile robot to traverse an elevator for the delivery service. In addition, an elevator boarding mission algorithm was developed to perceive the drivable region within the elevator and generate a feasible path that is collision-free. The algorithm was tested with real-world experiments and was demonstrated to perform autonomous postal delivery service in a multi-floor building. We concluded that our study could contribute to building a stable autonomous driving robot system for a multi-floor environment.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.11B
• /
• pp.938-945
• /
• 2004

This paper describes the problems of the existing two multi-layer routing policies(policy 1 and policy 2) and suggests new multi-layer routing policy(policy 3) which is established the packet LSP by inquiry on packet LSP lambda routing tables for GMPLS based optical If Network. All policies of multi-layer routing schemes first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. U such a path is not available, all policies employ different procedures. Policy 1 tries to find available existing optical paths with two or more hops that connect the source and destination nodes and policy 2 tries to establish a new one-hop optical path between source and destination nodes. Policy 3 tries to establish a new one-hop optical path by inquiry on information of the packet LSP lambda routing tables between source and destination nodes. The performances of the three multi-routing policies are evaluated by computer simulation. Simulation results show that policy 3 is the excellent of routing time and traffic acceptance capabilities compare to existing two polices if p is large, where p is the number of packet-switching-capable ports p.

• The KIPS Transactions:PartA
• /
• v.12A no.5 s.95
• /
• pp.461-470
• /
• 2005

In leaner-controlled environment where learners can decide and restructure the contents, methods and order of learning by themselves, it is possible to apply individualized learning in consideration of each learner's characteristics. The present study analyzed learners' learning path pattern, which is one of learners' characteristics important in Web-based teaching-learning process, using the Apriori algorithm and grouped learners according to their learning path pattern. Based on the result, we designed and implemented a multi-dimensional learning path pattern analysis system to provide individual learners with teaming paths, learning contents, learning media, supplementary teaming contents, the pattern of material presentation, etc. multi-dimensionally. According to the result of surveying satisfaction with the developed system satisfaction with supplementary learning contents was highest (Highly satisfied '$24.5\%$, Satisfied'$35.7\%$). By learners' level, satisfaction was higher in low-level learners (Highly satisfied'$20.2\%$, Satisfied'$31.2\%$) than in high-level learners (Highly satisfied'$18.4\%$, 'Satisfied'$28.54\%$). The developed system is expected to provide learners with multi-dimensionally meaningful information from various angles using OLAP technologies such as drill-up and drill-down.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.1
• /
• pp.35-40
• /
• 2019

It is important to constantly provide service in real-time multimedia applications using multicast. Transmission path reconstruction occurs in hybrid multicast using Internet Protocol (IP) multicast and ALM in order to adapt the network status to things like congestion. So, there is a problem in which real-time QoS is reduced, caused by an increase in end-to-end delay. In this paper, we want to solve this problem through multi-layer transmission path construction. In the proposed method, we deploy the control server and application layer overlay host (ALOH) in each multicast domain (MD) for hybrid multicast construction. After the control server receives the control information from an ALOH that joins the MD, it makes a group based on the hop count and sends it to the ALOH in each MD. The ALOH in the MD performs the role of sending the packet to another ALOH and constructs the multi-layered transmission path in order of priority by using control information that is received from the control server and based on the delay between neighboring ALOHs. When congestion occurs in, or is absent from, the ALOH in the upper MD, the ALOH selects the path with the highest priority in order to reduce end-to-end delay. Simulation results show that the proposed method could reduce the end-to-end delay to less than 289 ms, on average, under congestion status.

• Journal of Convergence Society for SMB
• /
• v.6 no.4
• /
• pp.17-23
• /
• 2016

With the advance of ICT, the Internet has been creating new services in various fields. However, due to the architectural problem of the Internet, it may inhibit the development of network architectures and various services. Network virtualization is being investigated as an alternative to overcome the architectural problem of the Internet and a virtual network resource allocation algorithm is a very important issue. In this paper, we propose a multiple path resource allocation algorithm with shared backup bandwidth in order to overcome single link failure. It will be improved survivability of the virtual networks. Through our experiments, we confirmed that the multi-path creation time of the proposed algorithm has about 50% performance improvement than previous works.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.4A
• /
• pp.291-301
• /
• 2009

In this paper, the effect of ISI(Inter-Symbol Interference) and ICI(Inter-Carrier Interference) due to time difference of arrival on OFDMA-based mobile multi-hop relay (MMR) systems is analyzed. Analyses are performed for the ISI caused by the previous OFDMA symbol transmitted from neighboring macro or relay cell as well as the ISI caused by the next OFDMA symbol transmitted from neighboring macro or relay cell. Then, an effective SINR(Signal to Interference plus Noise Ratio) estimation method and a path selection method considering time difference of arrival are proposed to minimize the effect of ISI and ICI. It is shown by simulation that the performance degradation caused by time difference of arrival can be significantly mitigated when the proposed path selection method is applied to the uplink of OFDMA-based MMR systems.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.11 no.3
• /
• pp.49-56
• /
• 2011

This paper deals with a methodology for searching optimal route of hazard material (hazmat) vehicles. When we make a decision of hazmat optimal paths, there is a conflict between the public aspect which wants to minimize risk and the private aspect which has a goal of minimizing travel time. This paper presents Efficient Vector Labeling algorithm as a methodology for searching optimal path of hazmat transportation, which is intrinsically one of the multi-criteria decision making problems. The output of the presented algorithm is a set of Pareto optimal paths considering both risk and travel time at a time. Also, the proposed algorithm is able to identify non-dominated paths which are significantly different from each other in terms of links used. The proposed Efficient Vector Labeling algorithm are applied to test bed network and compared with the existing k-shortest path algorithm. Analysis of result shows that the proposed algorithm is more efficient and advantageous in searching reasonable alternative routes than the existing one.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.11
• /
• pp.1071-1077
• /
• 2010

The reduction of the vehicle interior noise has been the main interest of noise and vibration harshness(NVH) engineers. A passenger vehicle has various and complicated transmission paths of sound and vibration. In order to identify the mechanism of transfer path, estimation of excitation force and exact modeling of transfer path are required. This paper presents method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. And vector synthesis technique is employed to identify the characteristics of road noise and its transmission to vehicle compartment through noise and vibration analysis. Vibration reduction efficiency of each transfer path is evaluated by comparing individual vector components obtained virtual simulation.