• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1722-1728
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• 2004

To discover a certificate path is a very important topic in the PKI with a lot of candidate paths. The certificate path discovery processing is executed via many verifications and as the number of verification times increases, the validity of the discovered path becomes high. The selection of the path with high validity provides high-speed certificate validation by reducing the number of repetition times of path discovery and validation processing. Otherwise, there is a problem that the speed and computation overheads are increased. In this paper, we propose an efficient certificate path discovery algorithm can make high the certificate validity with low overhead.

• Journal of Korea Multimedia Society
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• v.17 no.2
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• pp.191-199
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• 2014

The unicasting routing technology of VANET is very important for user convenience. Unicasting packets must be forwarded to the appropriate path in order to arrive to the destination. However, there are so many problems because the vehicle nodes have limited information related to the routing decision. In particular, packet delivery failure will be occurred by selecting the path already failed again. We call this problem as 'Failed Path Re-Selection Problem'. In this paper, we propose an enhanced rerouting function of VANET Routing. The proposed rerouting function uses the failed path information when rerouting function executed. For this rerouting function, failed path information will be stored in the packet whenever the routing fail occurred. By the comparison with the performance of legacy VANET routing function, the superiority of the proposed method can be seen.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1390-1411
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• 2024

Underwater Wireless Sensors Networks (UWSNs) are deployed in remotely monitored environment such as water level monitoring, ocean current identification, oil detection, habitat monitoring and numerous military applications. Providing scalable and efficient routing is very challenging in UWSNs due to the harsh underwater environment. The biggest difficulties are the nodes inherent movement due to water current, long delay in data transmission, low bandwidth of the acoustic signal, high error rate and energy scarcity in battery powered nodes. Many routing protocols have been proposed to solve the aforementioned problems. There are three broad categories of routing protocols namely depth based, energy based and vector-based routing. Vector Based Forwarding protocols perform routing through virtual pipeline by defining their radius which give proper direction to packets communication. We proposed a routing protocol termed as Path-Oriented Energy Scaled Expanded Vector Based Forwarding (PESEVBF). PESEVBF takes into account all parameters; holding time, the source nodes packets routing path and void holes creation on the second hop; PESEVBF not only considers the packet upward advancement but also focus on density of the forwarded nodes in terms of number of potential forwarding and suppressed nodes for path selection. Node selection in resultant holding time is based on minimum Path Factor (PF) value. Moreover, the suppressed node will be selected for packet forwarding to avoid the void holes occurrences on the second hop. Performance of PESEVBF is compared with other routing protocols using matrices such as energy consumption, packet delivery ratio, packets dropping ratio and duplicate packets creation indicating considerable performance improvement.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.520-522
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• 2004

In this paper, we propose the algorithm of path planning and obstacle avoidance for mobile robot. We call the proposed method Random Access Sequence(RAS) method. In the proposed method, a small region is set first and numbers are assigned to its neighbors, then the path is selected using these numbers. It has an advantage of fast planning and simple operation. This means that new path selection may be possible within short time and that helps a robot to avoid obstacle in any direction. When a robot meets moving obstacles, it avoids obstacles in a random direction. Sonar ranger is useful to get obstacle information and RAS may be a good solution for path planning.

• Journal of the Korea Society of Computer and Information
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• v.22 no.12
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• pp.95-100
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• 2017

In this paper, we propose a zone based ad hoc network construction scheme which support ad hoc path between nodes in local IoT networks consisting of IoT devices with the constrained feature, such as low power, the limited transmission rate and low computing capacity. Recently, the various routing protocols have been studied to support ad hoc networking of local IoT environments. This is, because basis RPL protocol is deigned to be used for the connecting service with Internet through gateway, ad hoc path between nodes in local IoT networks is not supported in basis RPL protocol. Thus, in this paper, the proposed routing scheme provides both ad hoc path and Infra path through gateway, supporting basis RPL protocol simultaneously. Through simulation, we show that the proposed routing scheme with zone based path selection scheme improves the performance of the success rate of end-to-end data transmission and the end-to-end delay, compared to basis RPL protocol.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.241-249
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• 2014

This paper presents a path planning algorithm of an autonomous vehicle (ADAM III) for collision avoidance in the presence of multiple obstacles. Under the requirements that a low-cost GPS is used and its computation should be completed with a sampling time of sub-second, heading angle estimation is proposed to improve performance degradation of its measurement and a hierarchical structure for path planning is used. Once it is decided that obstacle avoidance is necessary, the path planning consists in three steps: waypoint generation, trajectory candidate generation, and trajectory selection. While the waypoints and the corresponding trajectory candidates are generated based on position of obstacles, the final desired trajectory is determined with considerations of kinematic constraints as well as an optimal condition in a term of lateral deviation. Finally the proposed algorithm was validated experimentally through field tests and its demonstration was performed in Autonomous Vehicle Competition (AVC) 2013.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1917-1921
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• 1999

In this paper, we studied the method of path distribution in order to increase reliability of the network by reducing path congestion, solving the problems of increasing blocking statistics, and increasing the utilization of network resource. A scheme of efficient path calculation which can reduce the traffic congestion in an arbitrary link is proposed by path calculation equations considering link occupation rates. A rapid method of establishing a connection which can efficiently cope with accidental connection failure are studied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1960-1963
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• 2021

In this paper, we propose a multiplay Thompson sampling algorithm in multipath communication system. Multipath communication system has advantages on communication capacity, robustness, survivability, and so on. It is important to select appropriate network path according to the status of individual path. However, it is hard to obtain the information of path quality simultaneously. To solve this issue, we propose Thompson sampling which is popular in machine learning area. We find some issues when the algorithm is applied directly in the proposal system and suggested some modifications. Through simulation, we verified the proposed algorithm can utilize the entire network paths. In summary, our proposed algorithm can be applied as a path allocation in multipath-based communications system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2027-2032
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• 2003

For action selection as well as learning, simple associations between stimulus and response have been employed in most of literatures. But, for a successful task accomplishment, it is required that an animat can learn and express behavioral sequences. In this paper, we propose a novel action-selection-mechanism to deal with sequential behaviors. For this, we define behavioral motivation as a primitive node for action selection, and then hierarchically construct a network with behavioral motivations. The vertical path of the network represents behavioral sequences. Here, such a tree for our proposed ASM can be newly generated and/or updated, whenever a new sequential behaviors is learned. To show the validity of our proposed ASM, three 2-D grid world simulations will be illustrated.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.118-125
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• 2003

As consumer's desire becomes various, agility of mold manufacturing is the most important factor for competitive mold manufacturer. Decision making process is required to produce optimal result of CAM systems in using commercial CAM system to generate tool path. The paper proposes a methodology fur computer-assisted tool selection procedures for various cutting type of rough, semi-rough and finish cuts. The procedure provides assistance for machining tool selection by analyzing sliced CAD model section of die cavity and core. Information about machining time for the generated NC-code is used to aid the tool selection. The module is developed with commercial CAM API. This module will be used fur the optimization of tool selection and planning process.