• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.823-825
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• 1995

This paper presents an efficient and robust robot path planning technique that can always find a path, if one exists, in a densely cluttered, unknown and unstructured obstacle environment. The terrain in which the robot is expected to navigate is represented as a tesselated grid of square cells. The generated path is resolution complete and also resolution optimal once the terrain is fully explored by the robot or all the information about the terrain is given. The technique enables the accurate wave propagation to the diagonally adjacent cells and facilitates the implementations of various essential features for a real-time path planner such as partial updates and parallel computations.

• 한국CDE학회논문집
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• 제7권3호
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• pp.184-188
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• 2002

In 2D-Profile machining using cutter radius compensation cutter interferences are very common. To prevent the cutter interferences undercuts are inevitable in some regions of the profile. The undercut regions require cleanup machining using smaller radius tools. This paper considers a procedure of the tool path generation for the cleanup profile machining. And two methods are introduced for an efficient tool path generation. One is how to reduce the machining time by uniting adjacent tool paths of undercut regions, and the other is how to find the tool path with the minimal distance by applying TSP algorithm.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권2호
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• pp.252-256
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• 2010

구조적 조인은 효율적인 XML 질의 처리를 위한 핵심 연산자 중의 하나이다. 구조적 조인은 대용량의 XML 노드들을 대상으로 계층관계(조상-자손 및 부모-자식관계)를 형성하는 쌍을 효율적으로 계산한다는 측면에서, 경로패턴으로 표현된 질의를 처리하는 데 주로 사용될 수 있다. 하지만 구조적 조인 알고리즘은 XML의 경로 처리과정에서 많은 오버헤드를 야기 시킨다. 이에 대한 개선된 연산자인 구조적 세미조인은 효율적인 처리를 위하여 XML 노드간의 조인 결과를 조상노드 혹은 자손노드로 한정시키는 새로운 연산자이다. 본 논문에서는 구조적 세미조인 알고리즘을 소개하고, 구조적 세미조인을 이용한 경로처리 알고리즘을 제시한다. 실험을 통하여 개선된 방식의 구조적 세미조인 알고리즘이 XML 경로처리에 있어서 매우 효율적임을 보여준다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.371-388
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• 2014

Cognitive Radio (CR) has been recently proposed as a promising technology to remedy the problems of spectrum scarcity and spectrum underutilization by enabling unlicensed users to opportunistically utilize temporally unused licensed spectrums in a cautious manner. In Cognitive Radio Ad Hoc Networks (CRAHNs), data routing is one of the most challenging tasks since the channel availability and node mobility are unpredictable. Moreover, the network performance is severely degraded due to large numbers of path failures. In this paper, we propose the Fault-Tolerant Cognitive Ad-hoc Routing Protocol (FTCARP) to provide fast and efficient route recovery in presence of path failures during data delivery in CRAHNs. The protocol exploits the joint path and spectrum diversity to offer reliable communication and efficient spectrum usage over the networks. In the proposed protocol, a backup path is utilized in case a failure occurs over a primary transmission route. Different cause of a path failure will be handled by different route recovery mechanism. The protocol performance is compared with that of the Dual Diversity Cognitive Ad-hoc Routing Protocol (D2CARP). The simulation results obviously prove that FTCARP outperforms D2CARP in terms of throughput, packet loss, end-to-end delay and jitter in the high path-failure rate CRAHNs.

• International Journal of CAD/CAM
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• 제5권1호
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• pp.1-10
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• 2005

A new approach based on vector field clustering for tool path optimization of 5-axis CNC machining is presented in this paper. The strategy of the approach is to produce an efficient tool path with respect to the optimal cutting direction vector field. The optimal cutting direction maximizes the machining strip width. We use the normalized cut clustering technique to partition the vector field into clusters. The spiral and the zigzag patterns are then applied to generate tool path on the clusters. The iso-scallop method is used for calculating the tool path. Finally, our numerical examples and real cutting experiment show that the tool path generated by the proposed method is more efficient than the tool path generated by the traditional iso-parametric method.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.79-90
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• 2015

Multipath routing technique is recognized as one of the effective approaches to improve the reliability of data forwarding. However, the traditional multipath routing focuses only on how many paths are needed to ensure a desired reliability. For this purpose, the protocols construct additional paths and thus cause significant energy consumption. These problems have motivated the study for the energy-efficient and reliable data forwarding. Thus, this paper proposes an energy-efficient concurrent multipath routing protocol with a small number of paths based on interaction between paths. The interaction between paths helps to reinforce the multipath reliability by making efficient use of resources. The protocol selects several nodes located in the radio overlapped area between a pair of paths as bridge nodes for the path-interaction. In order to operate the bridge node efficiently, when the transmission failure has detected by overhearing at each path, it performs recovery transmission to recover the path failure. Simulation results show that proposed protocol is superior to the existing multipath protocols in terms of energy consumption and delivery reliability.

• 한국정보통신학회논문지
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• 제23권6호
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• pp.711-718
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• 2019

이진결정도는 고장수목 해석에서 기존의 Boolean Logic 해석법의 잘 알려진 대체 방법이다. 고장수목의 규모가 커짐에 따라 계산에 필요한 컴퓨터 연산시간과 자원이 급격하게 증가한다. 이진결정도로부터 단절집합 및 최소단절 집합을 효과적으로 계산하기 위해 새로운 고장경로 탐색법과 고장경로 재구성 방법이 제안되었다. 고장경로 그룹화와 Bottom-Up 탐색법은 고장경로의 탐색에 효율적임을 증명하였고, 최소단절집합 계산을 위한 단절집합의 비교계산 횟수를 줄이기 위해 경로 재구성 방법을 사용할 수 있음을 증명하였다. 새로 제안된 방법을 적용하고, 기존의 근사확률 공식인 MCUB 확률공식과 동일한 새로운 ASDMP 확률공식을 사용하여 정상사상 확률을 계산 할 수 있다.

• 한국ITS학회:학술대회논문집
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• 한국ITS학회 2004년도 제3회 정기총회 및 추계학술대회
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• pp.106-110
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• 2004

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1189-1192
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• 1996

Navigation is a science of directing a mobile robot as traversing the environment. The purpose of navigation is to reach a destination without getting lost or crashing into any obstacles. In this paper, we use a genetic algorithm for navigation. Genetic algorithm searches for path in the entire, continuous free space and unifies global path planning and local path planning. It is the efficient and effective method when compared with navigators using traditional approaches.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2318-2320
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• 1998

A genetic algorithm for global and local path planning and collision avoidance of mobil robot in unstructured workspace is proposed. The genetic algorithm searches for a path in the entire and continuous free space and unifies global path planning and local path planning. The simulation shows the proposed method is an efficient and effective method when compared with the traditional collision avoidance algorithms.