• 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.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.201-206
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• 2004

Laser scanner are getting used for inspection and reverse engineering in industry such as motors, electronic products, dies and molds. However, due to the lack of efficient scanning technique, the tasks become limited to the low accuracy purpose. The main reasons for this limitation for usefulness are caused from the optical drawback, such as irregular reflection, scanning direction normal to measuring surface, the influence of surface integrity, and other optical disturbances. To overcome these drawback of laser scanner, this study propose the mechanism to reduce the optical trouble by using the 2 kinds of rotational movement axis and by composing the spherical coordinate to scanning the surface keeping normal direction consistently. So, it could be designed and interfaced the measuring device to realize that mechanism, and then it could acquisite the accurate 3D form cloud data. Also, these data are compared with the standard master ball and the data acquisited from the touch point sensor, to evaluate the accuracy and stability of measurement and to demonstrate the implementation of an dental tooth purpose system

• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.136-145
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• 2009

The objective of the Intelligent Excavation System (IES) is to recognize the work environment and produce work plan and automatically control the excavator through integrating sensor and robot technologies. This paper discusses one of the core technologies of IES development project, development of 3D work environment modeling. 3D laser scanner is used for 3-dimensional mathematical model that can be visualized in virtual space in 3D. This paper describes (1) how the most appropriate 3D imaging system has been chosen; (2) the development of user interface and customization of the s/w to control the scanner for IES project; (3) the development of the mobile station for the scanner; (4) and the algorithm for the automatic registration of laser scan segments for IES project. The development system has been tested on the construction field and lessons learned and future development requirements are suggested.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.513-518
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• 2016

This paper presents a fast 3D mesh generation method using projection for line laser-based 3D scanners. The well-known method for 3D mesh generation utilizes convex hulls for 4D vertices that is converted from the input 3D vertices. This 3D mesh generation for a large set of vertices requires a lot of time. To overcome this problem, the proposed method takes (${\theta}-y$) 2D depth map into account. The 2D depth map is a projection version of 3D data with a form of (${\theta}$, y, z) which are intermediately acquired by line laser-based 3D scanners. Thus, our 2D-based method is a very fast 3D mesh generation method. To evaluate our method, we conduct experiments with intermediate 3D vertex data from line-laser scanners. Experimental results show that the proposed method is superior to the existing method in terms of mesh generation speed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.903-909
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• 2018

We propose laser scanner sensor system based walking pattern and tracking method of multiple human. This system uses laser scanners sensors and is applicable to wide and crowded area such as hospital and medical care center. The primary objective of this research is to promote the development of robust, repeatable and transferable software for security system that can automatically detect, track and follow people in public area. We developed the method of human identification for this system. Our method is following: 1. Best-walking pattern data are obtained by the help of human position and direction data obtained by laser scanners. 2. Human identification is conducted by calculating the correlation between the step length of walking human. It becomes possible to conduct human identification even in crowded scenes by estimating the movements of waling human' feet are periodic. In the experiment in the station, some effectiveness of this method became clear.

• Broadcasting and Media Magazine
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• v.6 no.2
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• pp.84-101
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• 2001

In this paper, we present a primitive system design of a super multi-view(SMV) 3-D display system based on a focused light array(FLA) concept using reflective vibrating scanner array(ViSA). The parallel beam scanning using a vibrating scanner array is performed by moving left and right an array of curvature-compensated mirrors or diamond-ruled reflective grating attached to a vibrating membrane. The parallel laser beam scanner array can replace the polygon mirror scanner which has been used in the SMV 3-D display system based on the focused light array(FLA) concept proposed by Kajiki at TAO(Telecommunications) Advancement Organization). The proposed system has great advantages in the sense that it requires neither huge imaging optics nor mechanical scanning pals. Some mathematical analyses and fundamental limitations of the proposed system are presented. The proposed vibrating scanner array, after some modifications and refinements, may replace polygon mirror-based scanners in the near future.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.458-464
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• 2015

This paper proposes a portable 3-D scanning technique using a laser pointer. 3-D scanning is a process that acquires surface information from an 3-D object. There have been many studies on 3-D scanning. The methods of 3-D scanning are summarized into some methods based on multiple cameras, line lasers, and light pattern recognition. However, those methods has major disadvantages of their high cost and big size for portable appliances such as smartphones and digital cameras. In this paper, a 3-D scanning system using a low-cost and small-sized laser pointer are introduced to solve the problems. To do so, we propose a 3-D localization technique for a laser point. The proposed method consists of two main parts; one is a fast recognition of input images to obtain 2-D information of a point laser and the other is calibration based on the least-squares technique to calculate the 3-D information overall. To verified our method, we carry out experiments. It is proved that the proposed method provides 3-D surface information although the system is constructed by extremely low-cost parts such a chip laser pointer, compared to existing methods. Also, the method can be implemented in small-size; thus, it is enough to use in mobile devices such as smartphones.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2170-2174
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• 2005

Selective Laser Sintering (SLS) is a useful rapid prototyping technique for the manufacture of three dimensional (3D) solid objects directly from a scanning data. A new approach called a Selective Multi-Laser Sintering (SMLS) system has been developed at Korea Institute Machinery & Materials (KIMM) as an industrial type SFFS. This SMLS machine is built with a frame, heaters, nitrogen supply part, laser system. This system uses the dual laser and 3D scanner made in $Solutionix^{TM}$ to improve the precision and speed for large objects. The three-dimensional solid objects are made of polyamide powder. The investigation on each part of SMLS system is performed to determine the proper theirs design and the effect of experimental parameters on making the 3D objects. The temperature of the system has a great influence on sintering the polymer. Because the stability of the powder temperature prevents the deformation of each layer, the controls of the temperature in both the system and the powders are very important during the process. Therefore, we simulated the temperature distribution of build room using the temperature analysis with ANSYS program. Selected radiant heater is used to raise temperature of powder to melting point temperature. The laser parameters such as scan spacing, scan speed, laser power and laser delay time affect the production the 3D objects too. The combination of the slow scan speed and the high laser power shows the good results without the layer curling. The work is under way to evaluate the effect of experimental parameters on process and to produce the various objects. We are going to experiment continuously to improve the size accuracy and surface roughness.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.265-272
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• 2019

For tracking a varying number of people using laser range finder, it is important to deal with appearance/disappearance of people due to various causes including occlusions. We propose a method for tracking people with automatic initialization by integrating observations from laser range finder. In our method, the problem of estimating 2D positions and orientations of multiple people's walking direction is formulated based on a mixture kalman filter. Proposal distributions of a kalman filter are constructed by using a mixture model that incorporates information from a laser range scanner. Our experimental results demonstrate the effectiveness and robustness of our method.