• 한국정밀공학회지
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• 제11권4호
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• pp.88-98
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• 1994

A new local path planning algorithm for free-ranging robots is proposed. Considering that a laser range finder has the excellent resolution with respect to angular and distance measurements, a simple local path planning algorithm is achieved by a directional weighting method for obtaining a heading direction of nobile robot. The directional weighting method decides the heading direction of the mobile robot by estimating the attractive resultant force which is obtained by directional weighting function times range data, and testing whether the collision-free path and the copen parthway conditions are satisfied. Also, the effectiveness of the established local path planning algorithm is estimated by computer simulation in complex environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.259-262
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• 2003

In this paper, we studied the path determination algorithm of the guidance robot for the visually impaired. Using the guidance robot for the visually impaired, the visually impaired can go to the destination where they want without other's heir. The navigation path of the guidance robot for the visually impaired must be the optimal path not only the shortest but also the most safe, which is different from a shortest path for common people. GPS and electronic map are used for the location information of the visually impaired. We corrected the error by converting the coordinates of location information from GPS, which includes maximum several tens of meters error, to the coordinates of electronic map. Information such as simple path and direction to the destination is not enough because it may be different between a going path from the start to the destination and a coming path from the destination to the start as around environment. So, we added information which can be dangerous for the visually impaired such as driveway, sidewalk without braille blocks, crosswalk, stairs and overpass, each has weight value as dangerous degree, when matching the GPS information to the electronic map, enough large as 1:5,000 scale.

• 한국컴퓨터정보학회논문지
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• 제19권2호
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• pp.31-37
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• 2014

기존의 허프 변환을 이용한 차량 주행 경로 검출 기법에서는 배경 영상이 복잡하지 않은 차량 주행 영상에서 주행선 이탈 여부를 판별하였다. 하지만 획득된 차량 주행 영상에는 도로의 장애물이나 그림자, 다른 차량 등 주행 경로 인식을 방해하는 요소들이 있으므로 주행 경로 검출에 있어서 매우 큰 장애물로 작용하였다. 이 논문에서는 퍼지 이진화 기법과 캐니 마스크를 적용함으로써 기존에 제안된 허프 변환만을 이용한 주행 경로 검출 기법보다 효과적인 주행 경로 검출 기법을 제안한다. 이 논문에서 제안한 주행 경로 검출 기법의 성능을 평가하기 위하여 20개의 영상을 대상으로 실험한 결과, 주행 경로를 검출하는 데에 더욱 효과적인 것을 확인하였다.

• 전기학회논문지
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• 제64권10호
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• pp.1479-1485
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• 2015

Robot's technology was very simple and repetitive in the past. Nowadays, robots are required to perform intelligent operation. So, path planning has been studied extensively to create a path from start position to the goal position. In this paper, potential field algorithm was used for path planning in dynamic environments. It is used for a path plan of mobile robot because it is elegant mathematical analysis and simplicity. However, there are some problems. The problems are collision risk, avoidance path, time attrition. In order to resolve path problems, we amalgamated potential field algorithm with the artificial neural network system. The input of the neural network system is set using relative velocity and location between the robot and the obstacle. The output of the neural network system is used for the weighting factor of the repulsive potential function. The potential field algorithm problem of mobile robot's path planning can be improved by using artificial neural network system. The suggested algorithm was verified by simulations in various dynamic environments.

• 한국통신학회논문지
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• 제36권6B호
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• pp.728-737
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• 2011

글로벌 물류에 있어 핵심 중의 하나인 화물 컨테이너의 위치와 봉인 여부 등의 상태 정보를 항만, 야적장, 선박 등의 적치 환경에서 실시간으로 전달하기 위해서는 우선 Ad-Hoc 네트워크 통신 기술이 필요하다. 본 논문에서는 금속 재질로 된 음영 환경 등의 제약사향을 가지고 컨테이너의 잦은 이동이 이루어지는 항만이나 야적장에 적합한 컨테이너 네트워크의 라우팅 프로토콜을 제안한다. 각각의 정보가 싱크 노드로 신뢰성 있게 전달되면서도 잦은 가입/이탈에 대응할 수 있는 간단한 메시 네트워크 알고리즘을 적용하였다. 경유노드가 문제가 생기자마자 대체 경로를 제공하고 주변 노드에게 알림으로써 즉각적인 최적경로를 유지한다 대체 경로 제공 기능을 가진 대표적 무선 Ad-Hoc 라우팅 프로토콜인 AODV와 시뮬레이션을 통한 성능을 비교하였다. 비교 결과, 제안한 라우팅 프로토콜이 가입/이탈이 빈번하고 링크 품질이 자주 변하는 환경에서 더 나은 성능을 가졌음을 확인하였다.

• 한국과학교육학회지
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• 제26권5호
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• pp.611-619
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• 2006

The aims of this study are to investigate science high school students' understanding of velocity and acceleration of a simple pendulum bob, and to investigate their understanding of inertia and gravitational force in the motion of a pendulum bob when the tension is removed. For the study, 46 students that had already studied the physical, concepts in simple pendulum were sampled from a science high school in a large city in Korea. For a comparison with general high school students' conceptions, 49 students were sampled from a general high school in the same city. The test tool for the investigation consisted of four drawing and simple-answering type questions developed by the authors. The outcomes of the study revealed that a substantial number of science high school students have misconceptions concerning acceleration in pendulum motion, and that many of them do not understand the relationship between force and acceleration. In addition, the results of the study showed that more than 30% of the students drew the path of a bob going along the tangential direction at the highest point of the motion, and approximately 20% of them drew the path of a bob falling straight down at the lowest point of the motion.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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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 Mechanical Science and Technology
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• 제17권12호
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• pp.1876-1885
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• 2003

The artificial potential field (APF) methods provide simple and efficient motion planners for practical purposes. However, these methods have a local minimum problem, which can trap an object before reaching its goal. The local minimum problem is sometimes inevitable when an object moves in unknown environments, because the object cannot predict local minima before it detects obstacles forming the local minima. The avoidance of local minima has been an active research topic in the potential field based path planing. In this study, we propose a new concept using a virtual obstacle to escape local minima that occur in local path planning. A virtual obstacle is located around local minima to repel an object from local minima. We also propose the discrete modeling method for the modeling of arbitrary shaped objects used in this approach. This modeling method is adaptable for real-time path planning because it is reliable and provides lower complexity.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.256-256
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• 2000

In this parer, we present a real-time path planning algorithm which is integrated the artificial potential field(APF) and simulated annealing(SA) methods for mobile robot. The APF method in path planning has gained popularity since 1990's. It doesn't need the modeling of the complex configuration space of robot, and is easy to apply the path planning with simple computation. However, there is a major problem with APF method. It is the formation of local minima that can trap the robot before reaching its goal. So, to provide local minima recovery, we apply the SA method. The effectiveness of the proposed algorithm is verified through simulation.

• 한국정밀공학회지
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• 제15권6호
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• pp.58-63
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• 1998

There are lots of factors that are related to the geometric characteristics of machined surface. Among them, the tool path and milling mode (up cut milling or down cut milling) are the easiest controllable machining conditions. Thus, the first objective of this research is to study the effects of them on the milled surface that is generated by an end milling tool. To get precision parts, not only the machining process but also the measurement of geometric tolerance is important. But, this measurement requires a lot of time, because the infinite surface points must be measured in the ideal case. So, the second objective is to propose a simple flatness measurement method that can be available instead of the 3-D geometric tolerance measurement method, using a scale factor and characterized points. Finally, it is also shown that the possibility of flatness improvement by shifting the consecutive fine cutting tool path as compared with the last rough cutting tool path.