• 한국통신학회논문지
• /
• 제29권12C호
• /
• pp.1722-1728
• /
• 2004

다수의 인증 경로가 존재하는 PKI 구조에서 인증 경로를 설정하는 것은 중요한 문제이다. 경로 설정은 다양한 검증을 통해 이루어지고 검증이 많을수록 경로의 유효성은 높아진다. 유효성 높은 경로의 선택은 경로 설정 및 검증 작업의 반복 횟수를 감소시킴으로서 고속의 인증서 검증이 가능하도록 하는 반면에 하나의 경로를 설정하는데 소요되는 시간 및 부담을 증가시킨다는 문제점을 가진다. 본 논문에서는 보다 적은 부합으로 경로의 유효성을 높일 수 있는 효율적인 인증 경로 설정 알고리즘을 제안한다.

• 한국멀티미디어학회논문지
• /
• 제17권2호
• /
• pp.191-199
• /
• 2014

도심에서의 VANET 통신을 위한 유니캐스팅 라우팅은 사용자 편의를 위해 매우 중요한 요소 기술이다. 유니캐스팅을 위해서는 적절한 경로로 패킷이 전달되어야 하는데 차량노드에서 활용 가능한 라우팅 관련정보에 한계가 있어 많은 문제가 발생한다. 특히 경로 재탐색 시 이미 실패한 경로를 다시 선택하고, 동일한 과정을 거쳐 또 다시 이전 실패 경로를 선택하게 되는 실패 경로 재 선택의 문제가 최종 패킷 전달 실패의 원인이 된다. 본 논문에서는 이러한 문제를 해결할 수 있는 VANET 유니캐스팅 라우팅의 경로 재탐색 기능강화 방안을 제안한다. 제안하는 경로 재탐색 기능은 이미 실패한 경로 정보를 패킷에 저장하여 경로 재탐색시 활용하도록 한다. 소스 라우팅을 기반으로 하는 기존의 VANET 라우팅 기법과의 성능 비교에서 제안한 방식의 우수성을 알 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제18권5호
• /
• pp.1390-1411
• /
• 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.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
• /
• pp.520-522
• /
• 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.

• 한국컴퓨터정보학회논문지
• /
• 제22권12호
• /
• pp.95-100
• /
• 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.

• 한국자동차공학회논문집
• /
• 제22권3호
• /
• pp.241-249
• /
• 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.

• 한국통신학회논문지
• /
• 제24권12A호
• /
• pp.1917-1921
• /
• 1999

본 논문은 기존의 방법론에서 발생되는 경로들의 편중현상과 이에 따른 블록킹 확률이 증대되는 문제를 완화시키고 자원의 사용 효율성을 확대하여 망의 신뢰성과 효율성을 높이기 위한 경로분산 방법론을 연구하였다. 즉, 경로계산 시 링크점유율을 고려한 경로계산식으로 임의의 링크에 트래픽이 집중되는 것을 막을 수 있는 보다 효과적인 경로계산법을 제안하였다. 또한 발생할 수 있는 연결장애에 대해 효과적으로 대응하여 빠르게 연결설정하는 방안에 대해 연구하였다.

• 한국정보통신학회논문지
• /
• 제25권12호
• /
• pp.1960-1963
• /
• 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
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2027-2032
• /
• 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.

• 한국정밀공학회지
• /
• 제20권1호
• /
• pp.118-125
• /
• 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.