• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.371-377
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• 2006

The purposes of this study were to assess the accuracy of measurements in pre-enlarged canals with small instruments and to compare the accuracies, in enlarged canal, with small size instruments and instruments that match the actual canal diameter using Root ZX, Bingo1020, SmarPex, and e-Magic Finder. Ten extracted teeth were embedded in an alginate model made for testing apex locators. A size 10 file was placed into the root canal until the tip of the file reached the plane of the major diameter of the foramen under a dental operating microscope at the 25 x magnification. The measurement was done with digital caliper and defined as actual length. Electronic length measurement with a size 10 file in pre-enlarged canal was done by reading the index indicating Apex of each device to gain a definite value After completion of canal enlargement to a size 45 file, each difference between actual length and electric measurement value with a size 10 and 40 files in enlarged canal was recorded as L10 and L40. The one-way ANOVA and Scheffe's multiple range tests were computed for analyze the differences among the four apex locators in the same group. The Student's t-test between L10 and L40 of each locator was done. The accuracies of electronic measurements were significantly different among the 4 devices. The file size made no difference on the accuracy of electronic measurement in enlarged canal with same device. The e-Magic Finder was the most accurate device among the 4 apex locators used in this study.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.1
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• pp.1-5
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• 1987

The authors carried out an experiment to determine the vertical opening of the midwater trawl, which is the same used in the former experiment in this series of studies. To determine the vertical opening of otter board and front weight, three fish finders were used. A 200 KHz fish finder set on board the research vessel was used to sound the depth of water. A transmitter of 50 KHz fish finder was set through the shoe plate of otter board to determine the height of otter board from the sea bed, and a transmitter of another 50 KHz fish finder was set downwardly on the net pendant right before the front weight to determine the height of weight from the sea bed. The depth of otter board and weight were calculated by subtract the height of those from the depth of water, respectively. To determine the vertical opening of mouth, a transmitter of net recorder was set on the head rope and the vertical opening of that to ground rope was directly read on the recording paper. The results obtained can be summarized as follows: 1. The rate of the depth of otter board to the length of warp was in the range of 0.44 to 0.25, and the depth was linearly shoaled about 5m per 0.1m/sec of the towing speed or per 20rpm of the main engine. The rate of the observed depth to the calculated depth of otter board was in the range of 0.92 to 0.080 with a decreasing tendancy in accordance with the increase of towing speed. 2. The depth of head rope was 2 to 3m deeper than that of otter board, and the vertical opening of net mouth was in the range of 22 to 19m, with a decreasing tendancy in accordance with the increase of towing speed, 3. The difference of depth between front weight and otter board was about 20m and 22m respectively in the length of warp 100m and 150m without distinct change in accordance with the towing speed. The depth of front weight was 2 to 3m shallower than that of ground rope. 4. The changing range of depth of head rope according to the revolution of main engine was about 4m per 20rpm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.64-73
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• 2012

In this paper, a new land preview system using laser range finder based on heave estimation algorithm is proposed. The proposed land preview system is an equipment which measures the shape of forward topography for autonomous vehicle. To implement this land preview system, the laser range finder is generally used because of its wide measuring range and robustness under various environmental condition. Then the current location of the vehicle has to be known to generate the shape of forward topography and sensors based on acceleration such as IMU and accelerometer are generally utilized to measure heave motion in the conventional land preview system. However the drawback to these sensors is that they are too expensive for low-cost vehicle such as mobile robot and their measurement error is increased for mobile robot with abrupt acceleration. In order to overcome this drawback, an algorithm that estimates heave motion using the information of odometer and previously measured topography is proposed in this paper. The proposed land preview system based on the heave estimation algorithm is verified through simulation and experiments for various terrain using a simulator and a real system.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.1
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• pp.23-30
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• 2009

This paper addresses how to make a formation of multiple unmanned aerial vehicles (UAVs) using only the relative range information. Since the relative range can easily be measured by an on-board range sensor like the laser range finder, the proposed method does not require any expensive and heavy wireless communication system to share the navigation information of each vehicle. Based on the two-dimensional (2-D) nonlinear equations of motion, we propose a nonlinear formation controller using the typical input-output feedback linearization method. The performance of the proposed formation controller is verified by various numerical simulations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.247-255
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• 1995

This paper describes a personal computer(PC) based color fish finder to improve some problem of the commercial one. The commercial fish finder has no function of the echo data logging and replaying. The authors developed two types of the PC based color fish finder. One is a master type composed of a PC, a digital input-output board, and analog to digital converting (A/D) board and an ultrasonic transceiver unit, the other is a slave type composed of a PC and an A/D board. To test the performances of the master type experiments were carried out in air and in a water tank. It is found that the designed master type fish finder displays very well an eight-colored echogram by one dot resolution to the left side of the PC monitor. Also, the depth of echo signal was corresponds very well to the range from the transducer to a target. The sampling interval of echo signal is about 0.1m and the time of A/D conversion is 30 $\mu$sec. On the other hand, to test the performances of the slave type a raw data of echo signals from a data logger was supplied directly or via RF transceivers to the slave type one. From this experiment, it is confirmed the slave type is useful to replay the echo signal from the data logger or a telesounder.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.8-15
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• 2011

This paper proposes a real-time navigation algorithm which integrates the artificial potential field (APF) for an unmanned vehicle in the unknown environment. This approach uses repulsive potential function around the obstacles to force the vehicle away and an attractive potential function around the goal to attract the vehicle. In this research, laser range finder is used as range sensor. An obstacle detected by the sensor creates repulsive vector. Differential global positioning system (DGPS) and digital compass are used to measure the current vehicle position and orientation. The measured vehicle position is also used to create attractive vector. This paper proposes a new concept of potential field based navigation which controls unmanned vehicle's speed and steering. The magnitude of repulsive force based on the proposed algorithm is designed not to be over the magnitude of attractive force while the magnitude is increased linearly as being closer to obstacle. Consequently, the vehicle experiences a generalized force toward the negative gradient of the total potential. This force drives the vehicle downhill towards its goal configuration until the vehicle reaches minimum potential and it stops. The effectiveness of the proposed APF for unmanned vehicle is verified through simulation and experiment.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.307-313
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• 2012

This paper proposes a hand-eye laser range finder (LRF) based welding plane recognition method for autonomous robotic welding. The robot welding is the process of joining a metal piece and the welding plane along the welding path predefined by the shape of the metal piece. Thus, for successful robotic welding, the position and direction of the welding plane should be exactly detected. If the detected position and direction of the plane is not accurate, the autonomous robotic welding should fail. For precise recognition of the welding plane, a line on the plane is detected by the LRF. For obtaining the line on the plane, the Hough transform is applied to the obtained data from the LRF. Since the Hough transform is based on the voting method, the sensor noise can be reduced. Two lines on the plane are obtained before and after rotation of the robot joint, and then the direction of the plane is calculated by the cross product of two direction vectors of two lines. For verifying the feasibility of the proposed method, the simulation with the robot simulator, RoboticsLab developed by Simlab Co. Ltd., is carried out.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.93-100
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• 2011

This study was conducted to verify the applicability of robot milking system through acquisition and analysis of model teat's position information using scanning range finder (SRF). Model teats, same size and shape as real teats, were designed to analyze the properties according to the material, distance error and angle error of the sensor. In addition, 2-dimensional distance information of each teats was obtained at same time with 4 teat models and the result were as follows. 1. In the case of the fingers on the experiment for selection of materials for teat model, the distance error was from 4.3 mm to 1.3 mm, average was 2.8 mm as a minimum record. In the case of rubber material, average distance error was 4.3 mm. So, this material was considered to be a most suitable model. 2. The distance error was maximum at 100 mm distance. The more distance increased, the less error increased up to 300 mm. Then the error increased after 300 mm and decreased again. 3. The maximum angle error of 10.1 mm was measured at $170^{\circ}$, in case of $70^{\circ}$ the error was 0.2 mm as a minimum value. There was no specific tendency to error of angle. 4. In the 2-dimensional location error for 4 teat models, distance error was 3.8 mm as minimum and 7.2 mm as maximum. The angle error was $1.2^{\circ}$ as maximum. All of errors were included within the accuracy of sensor, the robot milking system was considered to be applicable to measure the distance of teats due to the measuring velocity of SRF and the hole size of teat-cup.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.973-979
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• 2007

A laser vision system is developed to measure the three-dimensional feature of an object. This system consists of two low cost cameras and a cross laser. One camera and a cross laser are used to measure a plane equation of an object. Using this information, the other camera measures a hole size of an object. The proposed system provides 0.05 mm accuracy measurement systems with relatively low cost.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.134.5-134
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• 2001

The capability of environment recognition is very important for mobile robot. Especially, a function of target tracking is necessary in monitoring and watching an object using mobile robot. In general, vision sensors such as CCD camera and laser range finder were used for tracking of a moving target. However, they are not only affected by intensity of illumination in environment but also require high performance processors to process large amount of data. Therefore, in this paper, we propose the construction of target tracking system for mobile robot using only ultrasonic sensors to cope with these problems.