• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.471-472
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• 2013

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.638-641
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• 2004

Returned laser pulse has certain relationship with vegetation canopy structure (canopy closure, height, LAI, biomass). This study attempts to analyze the characteristics of airborne laser scanner data over very dense forest canopy. Discrete pulse laser scanner data were obtained on April 25, 2004 along with digital aerial color imagery. Using forest stand maps, 14 sample stands of 7 species groups were selected and the elevations from the first and last laser return were compared. From the preliminary analysis, we found that the difference between the first and last return was higher with deciduous forest stand than in coniferous stand. Although difference between the first and the last laser returns often corresponds to tree height, it would not be the case for the forest site having very dense canopy structure.

• Journal of Welding and Joining
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• v.29 no.6
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• pp.82-87
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• 2011

In this study, we conducted laser welding by using remote scanner that is 5J32 aluminum alloy to observe the mechanical properties and optimize welding process parameters. As the control factors, laser incident angle, laser power and welding speed were set and as the result of weldablility, tensile shear tests were performed. ANOVA (Analysis of Variation) was also carried out to identify the influence of process variables on tensile shear strength. Strength estimation models were suggested using regression alnalysis and 2nd order polynomial model had the best estimation performance. In addition optimal welding condition was determined in terms with wedalility and productivity using objective function and fitness function. Final optimized welding condition was laser power was 4 kW, and welding speed was 4.6 m/min.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.29-29
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• 2009

On this research, laser welding technology for manufacturing automobile body is studied. Laser welding technology is one of the important technologies used in the manufacturing of lighter, safer automotive bodies at a high level of productivity; the leading automotive manufacturers have replaced spot welding with laser welding in the process of car body assembly. Korean auto manufacturers are developing and applying the laser welding technology using a high output power Nd:YAG laser and a 6-axes industrial robot. On the other hand, the robot-based remote laser welding system was equipped with a long focal laser scanner system in robotic end effect. Laser system, robot system, and scanner system are used for realizing the high speed laser welding system. The remote laser welding system and industrial robotic system are used to consist of robot-based remote laser welding system. The robot-based remote laser welding system is flexible and able to improve laser welding speed compared with traditional welding as spot welding and laser welding. The robot-based remote laser systems used in this study were Trumpf's 4kW Nd:YAG laser (HL4006D) and IPG's 1.6kW Fiber laser (YLR-1600), while the robot systems were of ABB's IRB6400R (payload:120kg) and Hyundai Heavy Industry's HX130-02 (payload:130kg). In addition, a study of quality evaluation and monitoring technology for the remote laser welding was conducted. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The quality testing of the laser welding was conducted by observing the shape of the beads on the plate and the cross-section of the welded parts, analyzing the results of mechanical tension test, and monitoring the plasma intensity and temperature by using UV and IR detectors. Over the past years, Trumf's 4kW Nd:YAG laser and ABB's IRB6400R robot system was used. Nowadays, the new laser source, robot and laser scanner system are used to increase the processing speed and to improve the efficiency of processes. This paper proposes the robot-based remote laser welding system as a means of resolving the limited welding speed and accuracy of conventional laser welding systems.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.845-846
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• 2006

In this paper, we describe a capacitive position sensing and motion control scheme of a MEMS scanner used for laser display application. The laser displays can be made by scanning laser beams much the same way a CRT scans electron beams. So the accuracy of the scanner motion determines the quality of the displayed image. The MEMS scanner under consideration is composed of electrostatic comb electrodes with initial gap and requires large driving voltage. Due to the under-damping and nonlinear driving characteristics, the scanner motion is subject to be an unwanted oscillation. For the linear scanner motion, we devise a differential charge amplifier and phase compensator. The experimental results show that the implemented feedback control system provides sufficient electrical damping and improves the dynamic performance of the scanner.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.3
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• pp.21-27
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• 2010

When the capacity of underground caverns' structures is measured, a general surveying is difficult to decide an accurate section of irregular shape and a photographic surveying has problems on picture acquisition due to underground dusts, noise and lighting conditions, etc. The laser scanner system is being much used for 3-dimensional modeling such as topography, planimetric features and structures, etc. without a target by measuring arriving time of a laser pulse reflected after scanning the laser pulse and calculating space coordinates of the reflection position. Accordingly, the present research carried out section and earthwork volume measurement of a tunnel by using a laser scanner in underground anchorage excavation work that a bridge construction is being executed.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.555-562
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• 2010

Three-dimensional laser scanner was used to accurately measure any possible strain on a slope under pertaining stress with the time difference of 7 months. The laser scanner has the ability to measure the 3-D coordinate of a target point by calculating the travel time of laser beam between the laser device and the target point, and has been proved to be effective for analysis of the displacement of slopes or large construction. The scanning data measured with time difference were analyzed to find any strain by approaches of plane angle change, curvature variation, twist of frame, displacement of merging point, etc. From the analysis, some weak points showing heavily distorted shape were detected, which was used to design the reinforcement.

• Spatial Information Research
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• v.17 no.1
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• pp.39-49
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• 2009

3D terrestrial laser scanners record high precision three-dimensional coordinates of numerous points on an object surface in a short period of time, and is applied to a wide variety of fields including geodesy, and civil engineering, archaeology and architecture, and emergency service and defence, etc. However, most of terrestrial laser scanner utilized in homeland, were imported from foreign country, and also was not authorized formally as the surveying instrument. Therefore, standard test facility to calibrate and perform its evaluation in order to utilize it in a variety of fields is required. This study deals with the test facility of foreign countries for terrestrial laser scanner and suggest the establishment scheme of domestic test facility.

• Journal of Welding and Joining
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• v.26 no.5
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• pp.74-78
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• 2008

The laser welding of the car body and components has been spread in the automotive industry. The Nd:YAG laser welding system could be used in 3D welding with robot. However, this system cannot efficiently reduce the welding cycle time according to various welding sequences because the robot's moving time is same that of the resistant spot welding system. But the remote welding system with high power $CO_2$ laser and scanner makes it possible welding cycle time much faster than the robot laser welding system. In the $CO_2$ laser remote welding system, laser beam can be rapidly transferred to a workpiece by moving mirrors of scanner system. So, it makes reducing the cycle time of welding process and shaping various welding patterns easily. Therefore, in this paper, the characteristic of weld strength according to patterns of weld bead on $CO_2$ laser welding was investigated. Also, the relationship between shape of weld bead and value of tensile load was studied. Finally, the optimum remote welding condition for car bumper was investigated.

• Laser Solutions
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• v.14 no.2
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• pp.1-7
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• 2011

The latest trends of vehicle technology development are fuel efficiency improvement, body designs declining air resistance and lightweight of materials. Especially, as lightened weight of materials makes engine efficient so that vehicles keep the best performance, it is the best way to protect the environment and reduce fuel consumption. In this study, we conducted laser welding by using 3-dimension remote scanner that is 5J32 aluminium alloy. Furthermore, conduction experiment that was 3 times repeated for changing factors such as observing angle, laser power and welding speed. we observed exterior and cross section of weled part and tensile strength. When increasing laser power and decreasing laser speed, tensile strength increased. In order to evaluate factors that affect tensile strength qualitatively we conducted ANOVA. We assumed that the factors are observing angle, laser power and welding speed. Then we found that laser power and laser speed affect tensile strength. We conducted evaluation of weldability of aluminium alloy by above ways.