• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 추계학술발표대회 개요집
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• pp.62-65
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• 1999

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1998년도 특별강연 및 춘계학술발표 개요집
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• pp.204-207
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• 1998

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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• pp.71-74
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• 2001

• 자동차안전학회지
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• 제9권4호
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• pp.32-37
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• 2017

For automated vehicles, the integrity and fault tolerance of environment perception sensor have been an important issue. This paper presents radar, vision, lidar(laser radar) fusion-based fault detection algorithm for autonomous vehicles. In this paper, characteristics of each sensor are shown. And the error of states of moving targets estimated by each sensor is analyzed to present the method to detect fault of environment sensors by characteristic of this error. Each estimation of moving targets isperformed by EKF/IMM method. To guarantee the reliability of fault detection algorithm of environment sensor, various driving data in several types of road is analyzed.

• Journal of Welding and Joining
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• 제19권2호
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• pp.208-214
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• 2001

In this study, we constructed a visual sensor system for weld seam tracking in real time in GMA welding. A sensor part consists of a CCD camera, a band-pass filter, a diode laser system with a cylindrical lens, and a vision board for inter frame process. We used a commercialized robot system which includes a GMA welding machine. To extract the weld seam we used a inter frame process in vision board from that we could remove the noise due to the spatters and fume in the image. Since the image was very reasonable by using the inter frame p개cess, we could use the simplest way to extract the weld seam from the image, such as first differential and central difference method. Also we used a moving average method to the successive position data or weld seam for reducing the data fluctuation. In experiment the developed robot system with visual sensor could be able to track a most popular weld seam. such as a fillet-joint, a V-groove, and a lap-joint of which weld seam include planar and height directional variation.

• 제어로봇시스템학회논문지
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• 제6권12호
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• pp.1106-1112
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• 2000

In this paper, we present a vision system which measures the cross-section of a hot wire-rod in the steel plant. We developed a mobile vision system capable of accurate measurement, which is strong to vibration and jolt when moving. Our system uses green laser light sources and CCD cameras as a sensor, where laser sheet beams form a cross-section contour on the surface of the hot wire-rod and the reflected light from the wire-rode is imaged on the CCD cameras. We use four lasers and four cameras to obtain the image with the complete cross-section contour without an occlusion region. We also perform camera calibrations to obtain each cameras physical parameters by using a single calibration pattern sheet. In our measuring algorithm, distorted four-camera images are corrected by using the camera calibration information and added to generate an image with the complete cross-section contour of the wire-rod. Then, from this image, the cross-section contour of the wire-rod is extracted by preprocessing and segmentation, and its height, width and area are measured.

• 한국해양공학회지
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• 제32권6호
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• pp.511-517
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• 2018

This paper proposes a vision-based underwater laser scanner with separate structures for an underwater camera and a line laser projector. Because the two devices can be adaptively placed regardless of the features of the unmanned underwater vehicle (UUV), the scanner has significant advantages in relation to its availability and flexibility. Position calibration between the underwater camera and laser projector guarantees a 3D measuring performance with high accuracy. To verify the proposed underwater laser scanner, a test-bed system was manufactured, which consisted of the laser projector, camera, Pan&Tilt, and Attitude and Heading Reference System (AHRS). A camera-laser calibration test and simple 3D reconstruction test were performed in a water tank and the experimental results are reported.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.871-875
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• 2003

To detect and avoid obstacles is one of the important tasks of mobile navigation. In a real environment, when a mobile robot encounters dynamic obstacles, it is required to simultaneously detect and avoid obstacles for its body safely. In previous vision system, mobile robot has used it as either a passive sensor or an active sensor. This paper proposes a new obstacle detection algorithm that uses a stereo camera as both a passive sensor and an active sensor. Our system estimates the distances from obstacles by both passive-correspondence and active-correspondence using laser slit. The system operates in three steps. First, a far-off obstacle is detected by the disparity from stereo correspondence. Next, a close obstacle is acquired from laser slit beam projected in the same stereo image. Finally, we implement obstacle avoidance algorithm, adopting the modified Dynamic Window Approach (DWA), by using the acquired the obstacle's distance.

• Journal of Welding and Joining
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• 제30권4호
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• pp.38-43
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• 2012

Using a fiber laser heat source, an oil pressure sensor was fabricated to measure the pressure in commercial vehicles. A stepping motor was used for the rotational and translational motion in the diaphragms and hardware joining. Laser welding process algorism including shielding gas control and vision system was integrated by using LabVIEW software for the high quality welding and in-line monitoring purpose. For the maximum flexibility in pressure transmission to the pressure sensor, thin sheet metal diaphragm, $25{\sim}50{\mu}m$(SUS-316L), was used and the diaphragms were optimally designed with FEM analysis. The welded samples were cross-sectioned the observation showed that the maximum depth ratio was more than seven times of diaphragms. The maximum welding speed was measured to be as high as 50in/mm by the developed automation mechanism. The fabricated prototypes were tested for the proof pressure, spring constant and sealing. The FEM results of spring constant measurement was as accurate as up to 80% of the design value and the sensor was safely operated up to the nominal pressure of 10bars.

• 한국정밀공학회지
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• 제18권9호
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• pp.179-185
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• 2001

In this study, a visual sensor system for weld seam tracking the I-butt weld joints in GMA welding was constructed. The sensor system consists of a CCD camera, a diode laser with a cylindrical lens and a band-pass-filter to overcome the degrading of image due to spatters and arc light. In order to obtain the enhanced image, quantitative relationship between laser intensity and iris number was investigated. Throughout the repeated experiments, the shutter speed was set at 1-milisecond for minimizing the effect of spatters on the image, and therefore most of the spatter trace in the image have been found to be reduced. Region of interest was defined from the entire image and gray level of searched laser line was compared to that of weld line. The differences between these gray levels lead to spot the position of weld joint using central difference method. The results showed that, as long as weld line was within $^\pm$15$^\circ$from the longitudinal straight fine, the system constructed in this study could track the weld line successful1y. Since the processing time reduced to 0.05 sec, it is expected that the developed method could be adopted to high speed welding such as laser welding.