• 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.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.55-64
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• 2021

In this study, the operation method and accuracy of Terrestrial Laser Scanner(TLS) are reviewed and discussed by experimental measurements, and guidelines of TLS surveying operation are proposed. Ground control points and TLS station points were measured by TS and/or GPS, in TLS observation experiments, and wood targets were used which designed by this study team. RMSE accuracy of TLS scan shows that TLS surveying operation can be used in the topographic mapping of 1/250 scale and level of 1/100 BIM, the drone data also used in TLS data completeness. Additionally, as the results of the field experiment, the guidelines for TLS surveying operartions were proposed.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.4 s.34
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• pp.33-38
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• 2005

The goal of this study is to segment building points effectively utilizing scan-line characteristics of airborne laser scanner. Points are classified as to their altitude similarity and adjacency with other classified points, and point searching range for the classification is restricted within some number of scan-lines, preventing classification speed from lowering as the process goes on. Besides, we detected wrong discrimination of one object into more than two classes, then integrated them into a single class. Consequently we could discriminate points of each building from others, its annexes and none building points simultaneously.

• Korean Journal of Optics and Photonics
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• v.27 no.5
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• pp.165-173
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• 2016

In this paper, we propose a three-dimensional (3D) scanning system based on two line lasers. This system uses two line lasers with different wavelengths as light sources. 532-nm and 630-nm line lasers can compensate for missing scan data generated by geometrical occlusion. It also can classify two laser planes by using the red and green channels. For automatic registration of scanning data, we control a stepping motor and divide the motor's rotational degree of freedom into micro-steps. To this end, we design a control printed circuit board for the laser and stepping motor, and use an image processing board. To compute a 3D point cloud, we obtain 200 and 400 images with laser lines and segment lines on the images at different degrees of rotation. The segmented lines are thinned for one-to-one matching of an image pixel with a 3D point.

• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.569-574
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• 2008

Catenary and Pantograph are used to transmit electrical energy to electric railways. Catenary (Overhead Contact Lines) should be installed precisely and managed for stable train operations. But external factors such as weather, temperature, etc., or aging affect catenary geometry. Changed catenary stagger and height cause high voltage spark or instant electric contact loss. Big spark derived from contact loss can damage the pantograph carbon strip and overhead contact lines that might interrupt the train operations. Therefore, to prevent a big scale spark or electric contact loss, catenary maintenance are required catenary geometry measurement systems with catenary maintenance capability. In this paper, we describe the development of catenary height and stagger measurement system. The catenary height and stagger measurement system uses Acuity company's AR4000 Laser Range Finder for distance measurement and AccuRange Line Scanner for degree measurement. This system detects suspicious overhead line sections with excessive stagger and height stagger variance.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.109-109
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• 2009

최근 유럽의 완성차 업체에서 조립라인에 적용을 시작하고 있는 레이저 원격 용접기술은 저항 점용접에서의 문제점들을 동시에 해결하고 작업 시간을 획기적으로 감소시켜 생산성을 향상시킬 수 있는 용접공정으로 떠오르고 있다. 레이저 원격 용접기술은 레이저 빔을 용접부의 원거리에서 조사하여 용접하는 기술로서 레이저의 초점거리와 갈바노미터의 고속 이송를 이용한 최첨단 용접공정이다. 높은 생산성을 유지 하기 위하여 정확한 용접 컨트롤이 필요하지만, 레이저 용접의 경우 용접시 안전 문제로 육안으로 관찰하기가 힘들다. 이러한 문제를 해결하기 위하여 모니터링이 필수적이다. 기존의 레이저 모니터링으로는 음향 센서를 이용하여 음향을 측정하는 방법이나 UV 센서, IR 센서 등의 빛을 이용한 방법이 많이 사용되어왔다. 하지만 이 방법들은 간접적인 방법들로 노이즈에 민감하고 또 설치가 까다로운 단점이 있었다. 본 연구에서는 CCD 카메라를 이용하여 시스템의 복잡함을 줄이고 더 정확하고 빠르게 용접 현상을 관찰하기 위하여 동축 모니터링 시스템을 이용하였으며, 이를 통해 Keyhole을 관찰하고 센서를 이용한 용접 변수(레이저 출력, 용접 속도 등)의 변화에 따른 용접 현상을 규명하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.45-50
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• 2009

The environment exploration is an essential process for indoor robots such as clean robot and security robot. Apartment house and office building has common frame structure, but internal arrangement of each room may be slightly different. So, it is more convenient to use a common frame map than to build a new map at every time the arrangement is changed. In this case, it is important to recognize invariant features such as wall, door and window. In this paper, an indoor mobile robot is implemented, and by using the laser scanner data and line segment histogram with respect to segment orientation and distance, an environment exploration method is presented and tested. This robot is fitted with a laser scanner, gyro sensor, ultra sonic sensor and IR sensor, and programed with C language.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.107-113
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• 1999

Low-aberration holographic scanners that eliminate the need for lenses and mirrors promise to greatly reduce the cost of laser printers and image scanners. In this study, a holographic optical element that can simultaneously scan and focus a laser beam is designed with analytic ray tracing method. An analytic and experimental work is conducted in which we investigated the hologram structure and hologon configuration for linear aberration-free scanning. For a prototype scanner, a He-Ne laser is used to manufacture and reconstruct the hologram, and the measured bow is about $\pm$133$\mu\textrm{m}$ and spot size(half-intensity beamwidth) in under 100$\mu\textrm{m}$ for a 300 mm scan length without using a correcting lens or mirror. The diffraction efficiency is about 55$\pm$5%, which is acceptably flat. The experimentally measured results agrees with the computed values. From this fact, we can conclude that the computed results using ray tracing method are practical and useful values, and have a potential for use in high resolution laser printers.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.2
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• pp.27-32
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• 2001

In this paper, the three dimension scanner system employing the parallel camera model is discussed. The camera calibration process and the three dimension scanning algorithm are developed. The laser strip line is utilized for assisting stereo matching. An object being scanned rotates on the plate which is activated by a stepping motor, The world coordinate which is. the measured distance from the camera to the object is converted into the model coordinate. The facets created from the point. cloud of the model coordinate is used for rendering the scanned model by using the graphic library such as OpenGL. The unmatched points having no validate matching points are interpolated from the validate matching points of the vicinity epipolar lines.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.27-29
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• 2007

The visual implementation of 3-dimensional national environment is focused by the requirement and importance in the fields such as, national development plan, telecommunication facility deployment plan, railway construction, construction engineering, spatial city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies national geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. There it is needed to apply laser measurement technique in the spatial target object to obtain accuracy. Currently, the LiDAR data which combines the laser measurement skill and GPS has been introduced to obtain high resolution accuracy in the altitude measurement. In this paper, we first investigate the LiDAR based researches in advanced foreign countries, then we propose data a generation scheme and an algorithm for the optimal manage and synthesis of railway facility system in our 3-D spatial terrain information. For this object, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional railway model with long distance for 3D tract model generation.