• 융합보안논문지
• /
• 제8권2호
• /
• pp.95-102
• /
• 2008

본 논문에서는 simple node 토폴로지의 망 정보를 효율적으로 요약함으로써 망에서의 호 성공률, 액세스 타임을 향상시켜 망의 전체적인 QoS를 향상시키기 위한 토폴로지 요약 기법을 제안하였다. 제안된 기법에서는 대역폭과 지연 파라미터를 중심으로 라인 세그먼트를 이용하여 경계노드 사이의 다중 경로 정보를 요약함으로써 토폴로지 요약 정보를 줄이고 다중링크 요약에 유연성을 부여하여 망의 성능을 향상시킬 수 있었다. 제안된 기법의 성능을 평가하기 위해 기존의 simple node 토폴로지 요약 기법과 호 성공률, 접근시간에 대하여 컴퓨터 시뮬레이션을 통해 비교 분석하였다.

• 한국GIS학회:학술대회논문집
• /
• 한국GIS학회 2004년도 GIS/RS 공동 춘계학술대회 논문집
• /
• pp.241-246
• /
• 2004

The ocean signal that reaches the detector of an imaging system after multiple interactions with the atmospheric molecules and aerosols was retrieved from the total signal recorded at the top of the atmosphere (TOA). A simple method referred to as 'Path Extraction' applied to the Landsat-TM ocean imagery of turbid coastal water was compared with the conventional dark-pixel subtraction technique. The shape of the path-extracted water-leaving radiance spectrum resembled the radiance spectrum measured in-situ. The path-extraction was also extended to the SeaWiFS ocean color imagery and compared with the standard SeaWiFS atmospheric correction algorithm, which relays on the assumption of zero water leaving radiance at the two NIR wavebands (765 and 865nm). The path-extracted water-leaving radiance was good agreement with the measured radiance spectrum. In contrast, the standard SeaWiFS atmospheric correction algorithm led to essential underestimation of the water-leaving radiance in the blue-green part of the spectrum. The reason is that the assumption of zero water-leaving radiance at 755 and 865nm fails due to backscattering by suspended mineral particles. Therefore, the near infrared channels 765 and 865nm used fur deriving the aerosol information are no longer valid for turbid coastal waters. The path-extraction is identified as a simple and efficient method of extracting the path radiance largely introduced due to light interaction through the complex atmosphere carried several aerosol and gaseous components and at the air-sea interface.interface.

• 대한교통학회지
• /
• 제22권6호
• /
• pp.121-131
• /
• 2004

다수경로 알고리즘은 비루프경로(Loopless Path: 또는 Simple Path)와 루프경로(Loop Path)를 탐색하는 방안으로 대별된다. 알고리즘의 난이도 측면에서 일반적으로 비루프경로를 탐색하는 방안이 루프경로를 탐색하는 방안보다 많은 노력이 소요된다. 바꾸어 말하면, 루프경로 탐색방안이 알고리즘의 이해 및 활용성 측면에서 용이하다는 장점이 존재한다. 루프경로탐색방안에서 경로삭제방식(Path Deletion Method)이 가장 효율적인 알고리즘으로 알려져 있다. 경로삭제방식은 K번째의 최적경로를 탐색하기 위하여 K-1번째의 경로의 탐색금지 상황설정이 필요하며, 이를 네트워크의 변형된 확장형태(Enlarged Transform)를 통하여 추구하는 방식이다. 그러나 이 알고리즘은 경로상에 노드 및 링크의 반복이 허용되는 루프를 생성시켜 교통망에 적용하기에는 한계가 존재하는 단점이 있다. 본 연구에서 링크표지를 활용하여 루프를 제거하는 방안을 개발한다. 이를 위해 K-1번째 확장네트워크에서 링크표지를 갱신하는 과정에서 대상링크와 전 링크의 부분경로와의 관계를 고려하여 루프가 생성되지 않도록 링크표지를 확정하여 원천적으로 루프의 생성을 방지한다. 본 연구에서 제안하는 비루프 알고리즘은 노드비루프와 링크비루프로 구분되며, 노드비루프는 경로 상에서 노드의 반복이 존재하지 않는 일반적인 단순경로(Simple Path)를 의미하며, 링크비루프는 경로 상에 링크의 반복이 존재하지 않는 경로를 의미한다. 특히 링크비루프는 도시 교차로에서 발생하는 U-턴, P-턴의 덩굴망 통행행태를 설명하기 위한 중요개념으로 확대 정의된다. 사례연구를 통하여 제안된 알고리즘의 활용성을 검증한다.

• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2001년도 정기학술대회
• /
• pp.455-462
• /
• 2001

We propose a new method to evaluate the network reliability which greatly reduces the intermediate steps toward calculations of maximum capacity flow by excluding unnecessary simple paths contained in the set of failure simple paths. By using signed simple paths and signed flow, we show that our method is more efficient than that of Lee and Park (2001a) in the number of generated composite paths and in the procedure for obtaining minimal success composite paths. Numerical examples are given to illustrate the use and the efficiency of the method.

• 전기학회논문지
• /
• 제63권1호
• /
• pp.115-122
• /
• 2014

Mobile robot has been studied for long time due to its simple structure and easy modeling. Regarding path planning of the mobile robot, we suggest real-time hybrid path planning algorithm which is the combination of optimal path planning and real-time path planning in this paper. Real-time hybrid path planning algorithm modifies, finds best route, and saves calculating time. It firstly plan the route with real-time path planning then robot starts to move according to the planned route. While robot is moving, update the route as the best outcome which found by optimal path planning algorithm. Verifying the performance of the proposed method through the comparing real-time hybrid path planning with optimal path planning will be done.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.1824-1827
• /
• 1997

Majority of industrial robots are controlled by a simple joint servo control of joint actuators. In this type of control, the performance of control is influenced greatly by the joint interaction torques including Coriolis and centrifugal forces, which act as disturbance torques to the control system. As the speed of the robot increases, the effect of this disturbance torque increases, and makes the high speed-high precision control more difficult to achieve. In this paper, the joint disturbance torque of robots is analyzed. The joint disturbance torque is defined using the coefficients of dynamic equation of motion, and for the case of a 2DOF planar robot, the conditions for the maximum joint disturbance torques are identified, and the effect of link parameters and joint variables on the joint disturbance torque are examined. Then, a solutioin to the optimal path placement problem is proposed that minimizes the joint disturbance torque are examined. then, a solution to the optimal path placement problem is proposed that minimizes the joint disturbance torque during a straight line motion. the proposed method is illustrated using computer simulation. the proposed solution method cna be applied to the class of robots that are controlled by independent joint sevo control, which includes the vast majority of industrial robots. By minimizing the joint disturbacne torque during the motion, the simple joint servo controlled robot can move with improved path tracking accuracy at high speed.

• 대한치과보철학회지
• /
• 제25권1호
• /
• pp.253-267
• /
• 1987

The purpose of this study was to improve limitations and disadvantages of the mechanical pantograph and the Visi-Trainer, and to design the reliable and reproducible device mandibular movement tracking device (MMTD) that is more simple, convenient and save the chair time than the mechanical pantograph and Visi-Trainer. MMTD was consist of head frame, horizontal bar, condylar path tracking stylus holders, anterior path tracking stylus holder, two condylar path plastic recording plates, one anterior path plastic recording plate, toggles and open occlusal clutch. To prove the reliability and reproducibility of MMTD, a five adults were selected and mandibular condylar movement was recorded one time by the mechanical pantographic tracing and MMTD. The border movement recording of the mandibular incisor (frontal, sagittal and horizontal) was also recorded by Visi-Trainer and the MMTD. The obtained results were as follows; 1. The condylar movement path (sagittal, horizontal) of the MMTD was not coincidence with that of mechanical pantograph. 2. Measurements of the angulation which established between working and balancing path records by use of the mechanical pantograph and MMTD, there was no significance. 3. In a view of MMTD's reproducibility, there was revealed almost similar recording pattern. 4. The border movement recording of the mandibular incisor by the MMTD and the Visi-Trainer showed almost same reliability and reproducibility. 5. The subjects were able to his original mandibular movements by use of open occlusal clutch in the MMTD.

• Journal of Information Processing Systems
• /
• 제16권6호
• /
• pp.1324-1342
• /
• 2020

Various modified algorithms of rapidly-exploring random tree (RRT) have been previously proposed. However, compared to the RRT algorithm for collision avoidance with global and static obstacles, it is not easy to find a collision avoidance and local path re-planning algorithm for dynamic obstacles based on the RRT algorithm. In this study, we propose boundary-RRT*, a novel-algorithm that can be applied to aerial vehicles for collision avoidance and path re-planning in a three-dimensional environment. The algorithm not only bounds the configuration space, but it also includes an implicit bias for the bounded configuration space. Therefore, it can create a path with a natural curvature without defining a bias function. Furthermore, the exploring space is reduced to a half-torus by combining it with simple right-of-way rules. When defining the distance as a cost, the proposed algorithm through numerical analysis shows that the standard deviation (σ) approaches 0 as the number of samples per unit time increases and the length of epsilon ε (maximum length of an edge in the tree) decreases. This means that a stable waypoint list can be generated using the proposed algorithm. Therefore, by increasing real-time performance through simple calculation and the boundary of the configuration space, the algorithm proved to be suitable for collision avoidance of aerial vehicles and replanning of local paths.

• Journal of Electrical Engineering and Technology
• /
• 제10권2호
• /
• pp.676-687
• /
• 2015

Path planning algorithms are used to allow mobile robots to avoid obstacles and find ways from a start point to a target point. The general path planning algorithm focused on constructing of collision free path. However, a high continuous path can make smooth and efficiently movements. To improve the continuity of the path, the searched waypoints are connected by the proposed polynomial interpolation. The existing polynomial interpolation methods connect two points. In this paper, point groups are created with three points. The point groups have each polynomial. Polynomials are made by matching the differential values and simple matrix calculation. Membership functions are used to distribute the weight of each polynomial at overlapped sections. As a result, the path has $G^2$ continuity. In addition, the proposed method can analyze path numerically to obtain curvature and heading angle. Moreover, it does not require complex calculation and databases to save the created path.

• 한국통신학회논문지
• /
• 제28권9C호
• /
• pp.908-922
• /
• 2003

최근에 PKI(Public Key Infrastructure)는 인증 경로 고리 작업을 사용자로부터 Delegated Path Discovery (DPD)와 Delegated Path Validation (DPV) 서버에게로 위임하는 추세이다. DPD/DPV 서버 구현의 최적의 조건은 높은 신뢰성을 제공하면서 저렴한 비용과 단순한 구현을 통해 구축하는 것이다. 본 논문에서는 사용자들이 가장 신뢰하는 신뢰 CA(Trusted CA)에 VA(Validation Authority)기능을 추가하여, 이를 DPD/DPV 서버로 사용하는 새로운 인증 경로 처리 기법을 제안하였다. 제안한 기법은 기존의 신뢰 CA를 위임 서버로 사용하기 때문에 단순한 구현을 통해 높은 신뢰성을 획득할 수 있다. 더불어, 경로 처리 작업으로 인한 신뢰 CA의 부담을 감소하기 위해서, 서명 검증 작업을 경로 상의 다른 CA들에게 위임하고, 반복되는 경로에 대한 처리 작업을 생략하도록 함으로서, 신뢰 CA를 이용한 검증 작업이 보다 효율적이고 빠르게 수행될 수 있도록 하였다.