• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.310-316
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• 2017

The robot proximity and tactile sensors can be categorized into two groups: grip sensors and safety sensors. They have different performance requirements. The safety sensor should have long proximity range and fast response in order to secure enough response time before colliding with ambient objects. As for the tactile sensing function, the safety sensor need to be fast and compliant to mitigate the impact from a collision. In order to meet these requirements, we proposed and demonstrated a compliant integrated safety sensor suitable to human-friendly robots. An ultrasonic proximity sensor and a piezoelectric tactile sensor made of PVDF films have been integrated in a compliant PDMS structure. The implemented sensor demonstrated the maximum proximity range of 35 cm. The directional tolerance for 30 cm detection range was about ${\pm}15^{\circ}$ from the normal axis. The integrated PVDF tactile sensor was able to detect various impacts of up to 20 N in a controlled experimental setup.

• Journal of Biosystems Engineering
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• 제37권1호
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• pp.65-74
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• 2012

Purpose: An autonomous robot was developed for harvesting strawberries cultivated in bench-type systems. Methods: The harvest robot consisted of four main components: an autonomous vehicle, a manipulator with four degrees of freedom (DOF), an end effector with two DOFs, and a color computer vision system. Strawberry detection was performed based on 3D image and distance information obtained from a stereo CCD color camera and a laser device, respectively. Results: In this work, a Cartesian type manipulator system was designed, including an intermediate revolute axis and a double driven arm-based joint axis, so that it could generate collision-free motions during harvesting. A DC servomotor-driven end-effector, consisting of a gripper and a cutter, was designed for gripping and cutting the strawberry stem without damaging the strawberry itself. Real-time position tracking algorithms were developed to detect, recognize, trace, and approach strawberries under natural light conditions. Conclusion: The developed robot system could harvest a strawberry within 7 seconds without damage.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.84-88
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• 2008

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by appling the most efficient detecting methods and verified the system's reliability through experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1183_1184
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• 2009

The synchronized visual message system device of level crossing provides warning system with the use of developed corresponding technology when the train is approaching forward to limited distance in level crossing. To ensure of safety driving for coming transit from road, it detect the location and velocity of train and transport the information to wayside warning device to prevent the collision with train. This paper is about the detailed design of synchronize VMS for passing transit at the level crossing and develop the physical contents of level crossing VMS with expression words, operational device, massage transportation algorism which are based on the proto type study of communication method and information contents for level crossing VMS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권7호
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• pp.1721-1736
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• 2013

Black and gray hole attack is one kind of routing disturbing attacks and can bring great damage to the network. As a result, an efficient algorithm to detect black and gray attack is important. This paper demonstrate an adaptive approach to detecting black and gray hole attacks in ad hoc network based on a cross layer design. In network layer, we proposed a path-based method to overhear the next hop's action. This scheme does not send out extra control packets and saves the system resources of the detecting node. In MAC layer, a collision rate reporting system is established to estimate dynamic detecting threshold so as to lower the false positive rate under high network overload. We choose DSR protocol to test our algorithm and ns-2 as our simulation tool. Our experiment result verifies our theory: the average detection rate is above 90% and the false positive rate is below 10%. Moreover, the adaptive threshold strategy contributes to decrease the false positive rate.

• 로봇학회논문지
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• 제15권1호
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• pp.55-61
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• 2020

Getting on and off an elevator is one of the most important parts for multi-floor navigation of a mobile robot. In this study, we proposed the method for the pose recognition of elevator doors, safe path planning, and motion estimation of a robot using RGB-D sensors in order to safely get on and off the elevator. The accurate pose of the elevator doors is recognized using a particle filter algorithm. After the elevator door is open, the robot builds an occupancy grid map including the internal environments of the elevator to generate a safe path. The safe path prevents collision with obstacles in the elevator. While the robot gets on and off the elevator, the robot uses the optical flow algorithm of the floor image to detect the state that the robot cannot move due to an elevator door sill. The experimental results in various experiments show that the proposed method enables the robot to get on and off the elevator safely.

• 로봇학회논문지
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• 제8권4호
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• pp.238-246
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• 2013

In this paper, a robot vision technique is presented to detect obstacles, particularly approaching humans, in the images acquired by a mobile robot that autonomously navigates in a narrow building corridor. A single low-cost color camera is attached to the robot, and a trapezoidal area is set as a region of interest (ROI) in front of the robot in the camera image. The lower parts of a human such as feet and legs are first detected in the ROI from their appearances in real time as the distance between the robot and the human becomes smaller. Then, the human detection is confirmed by detecting his/her face within a small search region specified above the part detected in the trapezoidal ROI. To increase the credibility of detection, a final decision about human detection is made when a face is detected in two consecutive image frames. We tested the proposed method using images of various people in corridor scenes, and could get promising results. This method can be used for a vision-guided mobile robot to make a detour for avoiding collision with a human during its indoor navigation.

• Journal of Computational Design and Engineering
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• 제2권1호
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• pp.55-66
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• 2015

To satisfy safety regulations of Economic Commission for Europe (ECE), the surface regions of automobile parts must have a sufficient degree of roundness if there is any chance that they could contact a sphere of 50.0 mm radius (exterior parts) or 82.5 mm radius (interior parts). In this paper, a new offset-based method is developed to automatically detect the possible sphere-contacting shape of such parts. A polyhedral model that precisely approximates the part shape is given as input, and the offset shape of the model is obtained as the Boolean union of the expanded shapes of all surface triangles. We adopt a triple-dexel representation of the 3D model to enable stable and precise Boolean union computations. To accelerate the dexel operations in these Boolean computations, a new parallel processing method with a pseudo-list structure and axis-aligned bounding box is developed. The possible sphere-contacting shape of the part surface is then extracted from the offset shape as a set of points or a set of polygons.

• 전기전자학회논문지
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• 제22권2호
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• pp.440-445
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• 2018

본 논문은 미지 유동환경에서 다중 이동로봇들의 주행문제에 대한 연구결과이다. 여기에서 환경은 로봇에게는 알려져 있지 않기 때문에 로봇의 몸체에 부착된 근접센서들을 이용하여 주변환경들을 감지하여야 하고, 로봇이 충돌 없이 경로를 추적하여 목표지점에 도착하도록 기본 방책들을 조합한 지능주행 방법을 제안하였다. 이러한 대부분 기법들은 퍼지논리 제어기들을 이용하여 구현하였으며, 모든 로봇에 동일하게 적용하였다. 퍼지 제어기의 성능을 향상시키기 위해서 유전 알고리즘을 이용하여 퍼지 제어기의 membership function과 rules set를 진화시켰다. 모의실험 결과 제안한 방법이 주행문제에 긍정적인 결과가 있음이 증명되었다.

• 전자공학회논문지CI
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• 제39권2호
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• pp.21-34
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• 2002

구조화된 환경에서 사용되어 지는 일반적인 이동 로봇과 달리 시각장애인을 위한 이동 로봇은 다양한 종류의 이동 장애물들을 고려하도록 설계되어야 한다. 그런데, 이동 장애물, 즉 보행자의 대부분은 어떤 의도를 가지고 이동하게 되므로 로봇이 그 의도를 미리 파악하면서 주행한다면 로봇은 지능적인 주행을 할 수가 있다. 본 논문에서는 격자형 맵을 이용하여 장애물의 의도를 추론하는 방법을 제안하다. 먼저 퍼지 논리와 초음파 센서를 이용하여 주위 환경을 격자형 맵으로 표현하고, 격자형 맵의 CLA(Centroid of Largest Area)점을 이용한 장애물 감지 방법 및 장애물 의도 추론 방법을 제안한다. 제안된 방법의 유용성을 확인하기 위해 실험이 수행되었다.