• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권3호
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• pp.245-249
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• 2012

In this paper, we propose a navigation algorithm for a mobile robot, which is intelligently searching the goal location in unknown dynamic environments using an ultrasonic sensor. Instead of using "sensor fusion" method which generates the trajectory of a robot based upon the environment model and sensory data, "command fusion" method is used to govern the robot motions. The navigation strategy is based on the combination of fuzzy rules tuned for both goal-approach and obstacle-avoidance. To identify the environments, a command fusion technique is introduced, where the sensory data of ultrasonic sensors and a vision sensor are fused into the identification process.

• 해양환경안전학회지
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• 제25권2호
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• pp.178-188
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• 2019

충돌 피항 동작은 선박 간 끊임없이 영향을 주고받는다. 특히 다수의 선박이 조우하는 경우, 상대 선박의 피항 의도를 파악하고 서로에게 얼마나 영향을 미치는 지를 파악하는 것은 어려운 일이다. 이를 위해 분산 확률 탐색 알고리즘이 제안되었다. 분산 확률 탐색 알고리즘은 이웃 선박과 반복적인 메시지 교환을 통해 비용을 가장 크게 낮출 수 있는 코스를 탐색 후 확률과 제한 조건에 따라 기존의 코스를 유지할지 아니면 새로운 코스를 선택할지를 결정한다. 그러나 분산 확률 탐색 알고리즘에 사용된 파라미터가 충돌 피항에 어떠한 영향을 미치는지 증명되지 않았다. 본 논문에서는 분산 확률 탐색 알고리즘의 파라미터와 가중치가 충돌 피항에 어떠한 영향을 미치는지 분석하였다. 또한 타선과의 피항 거리를 조절하기 위한 충격 흡수 영역을 소개한다. 실험 방법은 두 선박이 조우할 수 있는 세 가지 상황, 즉 정면에서 조우하는 상황, 횡단하는 상황, 추월하는 상황에 파라미터와 가중치의 변수들을 조합하여 실험을 진행하였다. 각 상황 당 8,000회, 총 24,000회의 실험이 진행되었다. 실험 결과 모든 실험에서 한 건의 충돌도 발생하지 않았다. 선박이 목적지에 큰 가중치를 줄 경우, 즉 이기적인 행동을 할 경우, 비용은 증가함을 보였다. 타선의 움직임을 더 길게 예측할수록 항행 거리, 메시지 교환 횟수는 작아지는 경향을 보였다.

• 전기학회논문지
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• 제58권12호
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• pp.2498-2504
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• 2009

The fundamental research for the mobile robot navigation using the numerical optimization method is presented. We propose an image-based visual servo navigation algorithm for a wheeled mobile robot utilizing a ceiling mounted camera. For the image-based visual servoing, we define the composite image Jacobian which represents the relationship between the speed of wheels of a mobile robot and the robot's overall speed in the image plane. The rotational speed of wheels of a mobile robot can be directly related to the overall speed of a mobile robot in the image plane using the composite image Jacobian. We define the mobile robot navigation problem as an unconstrained optimization problem to minimize the cost function with the image error between the goal position and the position of a mobile robot. In order to avoid the obstacle, the modified cost function is proposed which is composed of the image error between the position of a mobile robot and the goal position and the distance between the position of a mobile robot and the position of the obstacle. The performance was evaluated using the simulation.

• 대한임베디드공학회논문지
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• 제13권2호
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• pp.65-71
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• 2018

In order to make the underwater vehicle carry out the mission in a submarine environment, it is needed to plan a safe and efficient route to a given destination and prevent the autonomous submersible from colliding with obstacles while moving along the planned route. The function of collision avoidance makes the travel distance of the autonomous submersible longer. Moreover, it should move slowly near to obstacles against their moving disturbance. As a result, this invokes the degradation of the navigation efficiency in the process of collision avoidance. The side effect of the collision avoidance is not ignorable in the case of high congested environments such as the coast with many obstacles. In this paper, we suggest a path planning method which provides the route with minimum travel time considering collision avoidance in congested environment. For the purpose, we define environmental congestion map related to geometric information and obstacles. And we propose a method to consider the moving cost in the RRT scheme that provides the existing minimum distance path. We verified that the efficiency of our algorithm with simulation experiments.

• 경영과정보연구
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• 제36권3호
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• pp.255-268
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• 2017

본 연구는 기업의 CSR성과가 조세회피성향에 미치는 영향을 알아보고자 하며, 이러한 관련성이 최고경영자의 교체에 따라 차별적 영향력이 있는지를 알아보고자 한다. CSR 관련 연구는 지금까지 많은 주제와 연관되어 이루어졌으나, 어느 분야에서도 일관된 연구결과는 보고되지 못하고 있다. 따라서, 본 연구는 기존의 연구방법과는 달리 다른 영향요인을 추가하는 메커니즘으로 접근하고자 한다. 즉, 선행연구를 다음과 같은 방법으로 확장하였다. 첫째, 선행연구들은 CSR활동과 조세회피의 관련성 또는 CSR활동과 최고경영자의 교체 등의 개별적 주제로 다루어왔으나, 본 연구는 이러한 주제를 관련지어 CSR성과와 조세회피관련성에 CEO교체가 추가적인 역할을 하는지를 알아보고자 한다. 연구 결과를 요약하면, 첫째, CSR활동에 적극적인 기업은 최고경영자교체에 양(+)의 영향을 미치는 것으로 나타나, 최고경영자의 교체확률이 더 높음을 확인할 수 있었고, 둘째, CSR성과와 조세회피는 음(-)의 관계가 나타나 적극적으로 CSR활동을 이행하는 기업은 공격적 조세회피성향이 감소함을 확인하였다. 셋째, CSR활동기업의 조세회피성향에 최고경영자의 교체가 영향을 미치는지를 알아본 결과, 적극적인 CSR활동기업은 최고경영자의 교체 후, 조세회피성향은 완화됨을 확인할 수 있었다. 본 연구는 기업의 적극적인 CSR이행 효과가 기업의 주요 관심사인 현 상황에서, 기업의 주요 의사결정인 경영자교체와 관련지어 조세회피성향에 미치는 영향을 분석하였음에 의미를 찾을 수 있다.

• 산경연구논집
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• 제10권12호
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• pp.15-23
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• 2019

Purpose : We will develop the distribution method of wide oil extract technology to develop repellent using this technology and study mosquito repellent persistence. Research design, data and methodology : A positive control group containing purified water, ethanol and picaridin was prepared, and the experimental control group was prepared in the same proportion as the positive control group, and 0.6% of broad oil was added. The results were summarized using the calculation method according to the avoidance effect and statistically tested by t-test using the excel statistics program. Results : Experiments on skin surface area and voice control of participants showed that men had 8.9% wider skin surface area than women, and voice control tests showed that women were bitten by mosquitoes five times more than men. Both the positive and the experimental control groups had a valid duration of up to three hours, but from the time of five hours, the positive control group had 77% and the experimental control had 90%, indicating a difference of 14.4% over the positive control group. Conclusions : The mosquito repellents developed in this study on the basis of safety and continuity are cost-effective in terms of mosquito repellent, and in addition fragrance, odor removal, perfume, ink, skin care and massage effect.

• 한국정밀공학회지
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• 제29권12호
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• pp.1321-1330
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• 2012

This paper describes an advanced formation algorithm of clustered multiple robots for their navigation using flexible formation method for collision avoidance under static environment like narrow corridors. A group of clustered multiple robots finds the lowest path cost for navigation by changing its formation. The suggested flexible method of formation transforms the basic group of mobile robots into specific form when it is confronted by particular geographic feature. In addition, the proposed method suggests to choose a leader robot of the group for the obstacle avoidance and path planning. Firstly, the group of robots forms basic shapes such as triangle, square, pentagon and etc. depending on number of robots. Secondly, the closest to the target location robot is chosen as a leader robot. The chosen leader robot uses $A^*$ for reaching the goal location. The proposed approach improves autonomous formation characteristics and performance of all system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1939-1943
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• 1991

Path planning is an important task for optimal motion of a robot in structured or unstructured environment. The goal of this paper is to plan the shortest collision-free path in 3D, when a robot is navigated to pick up some tools or to repair some parts from various locations. To accomplish the goal of this paper, the Path Coordinator is proposed to have the capabilities of an obstacle avoidance strategy[3] and a traveling salesman problem strategy(TSP)[23]. The obstacle avoidance strategy is to plan the shortest collision-free path between each pair of n locations in 2D or in 3D. The TSP strategy is to compute a minimal system cost of a tour that is defined as a closed path navigating each location exactly once. The TSP strategy can be implemented by the Neural Network. The obstacle avoidance strategy in 2D can be implemented by the VGraph Algorithm. However, the VGraph Algorithm is not useful in 3D, because it can't compute the global optimality in 3D. Thus, the Path Coordinator is proposed to solve this problem, having the capabilities of selecting the optimal edges by the modified Genetic Algorithm[21] and computing the optimal nodes along the optimal edges by the Recursive Compensation Algorithm[5].

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.79-84
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• 1992

Path planning is an important task for optimal motion of a robot in structured or unstructured environment. The goal of this paper is to plan the optimal collision-free path in 3D, when a robot is navigated to pick up some tools or to repair some parts from various locations. To accomplish the goal, the Path Coordinator is proposed to have the capabilities of an obstacle avoidance strategy and a traveling salesman problem strategy (TSP). The obstacle avoidance strategy is to plan the shortest collision-free path between each pair of n locations in 2D or in 3D. The TSP strategy is to compute a minimal system cost of a tour that is defined as a closed path navigating each location exactly once. The TSP strategy can be implemented by the Hopfield Network. The obstacle avoidance strategy in 2D can be implemented by the VGraph Algorithm. However, the VGraph Algorithm is not useful in 3D, because it can't compute the global optimality in 3D. Thus, the Path Coordinator is used to solve this problem, having the capabilities of selecting the optimal edges by the modified Genetic Algorithm and computing the optimal nodes along the optimal edges by the Recursive Compensation Algorithm.

• 한국정밀공학회지
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• 제15권6호
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• pp.107-115
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• 1998

A path planning using potential field method is very useful for the real-time navigation of mobile robots. However, the method needs high modeling cost to calculate the potential field because of complex preprocessing, and mobile robots may get stuck into local minima. In this paper, An efficient path planning algorithm for multiple mobile robots, based on the potential field method, was proposed. In the algorithm. the concepts of subgoals and obstacle priority were introduced. The subgoals can be used to escape local minima, or to design and change the paths of mobile robots in the work space. In obstacle priority, all the objects (obstacles and mobile robots) in the work space have their own priorities, and the object having lower priority should avoid the objects having higher priority than it has. In this paper, first, potential based path planning method was introduced, next an efficient collision-avoidance algorithm for multiple mobile robots, moving in the obstacle environment, was proposed by using subgoals and obstacle priority. Finally, the developed algorithm was demonstrated graphically to show the usefulness of the algorithm.