• Title, Summary, Keyword: 레이저스캐닝

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Development of a Laser-Generated Ultrasonic Inspection System by Using Adaptive Error Correction and Dynamic Stabilizer (적응적 에러 보정과 다이나믹 안정기를 이용한 레이저 유도 초음파 검사 시스템 개발)

  • Park, Seung-Kyu;Baik, Sung-Hoon;Park, Moon-Cheol;Lim, Chang-Hwan;Ra, Sung-Woong
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.5
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    • pp.391-399
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    • 2005
  • Laser-generated ultrasonic inspection system is a non-contact scanning inspection device with high spatial resolution and wide bandwidth. The amplitude of laser-generated ultrasound is varied according to the energy of pulse laser and the surface conditions of an object where the CW measuring laser beam is pointing. In this paper, we correct the generating errors by measuring the energy of pulse laser beam and correct the measuring errors by extracting the gain information of laser interferometer at each time. h dynamic stabilizer is developed to stably scan on the surface of an object for an laser-generated ultrasonic inspection system. The developed system generates ultrasound after adaptively finding the maximum gain time of an laser interferometer and processes the signal in real time after digitization with high speed. In this paper, we describe hardware configuration and control algorithm to build a stable laser-generated ultrasonic inspection system. Also, we confirmed through experiments that the proposed correction method for the generating errors and measuring errors is effective to improve the performance of a system.

Deformation Analysis of Dam Structure using Terrestrial Laser Scanning System (지상 레이저 스케닝 자료를 활용한 댐체의 변형해석)

  • Kim, Young-Kyung;Shon, Ho-Woong;Im, Eun-Sang;Lim, Jeong-Yeol;Kim, Ki Young
    • Journal of the Korean Geophysical Society
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    • v.9 no.4
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    • pp.333-341
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    • 2006
  • Since considerable time passed after completion of dam construction, Methods to judge the safety and/or to manage effectively have extreme limitation and restriction. Behavior analysis based on one point (site) by such as surface settlement gauge is typically performed in order to define deformation characteristic of dam. However, deformation characteristics of entire dam can not be analyzed by this method. This study adopted state-of-the-art terrestrial laser scanning technology, and developed the technology to analyze the entire deformation of dam. The analysis was compare with the outputs of surface settlement gauge to confirm the performance of 3D terrestrial laser scanning technology. As a result, through analyses of laser scanning data and the surface settlement gauge data, the studied dam shows behavior of deformation by own weight of dam. It is possible to confirm that the dam is entering the stage of stabilization presently.

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The Study on Reconnaissance Surveying Using Terrestrial Laser Scanner (지상 라이다를 활용한 현황측량 연구)

  • Lee, In-Su;Kang, Sang-Gu
    • Journal of Korean Society for Geospatial Information System
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    • v.14 no.3
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    • pp.79-86
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    • 2006
  • Nowadays 3D terrestrial laser scanners record high precision three-dimensional coordinates of numerous points on an object surface in a short period of time. So terrestrial laser scanner is applied to a wide variety of fields including geodesy, and civil engineering, archaeology and architecture, and emergency service and defence, etc. This study deals with the potential application of terrestrial laser scanner in the reconnaissance surveying. The results shows that terrestrial laser scanner is possible to extract the linear features and the positioning accuracy of objects measured by total station surveying is comparative to that by terrestrial laser scanner. Thereafter, it is expected that the potential applications of terrestrial laser scanning will be more increased by combining terrestrial laser scanners with airborne LiDAR (Light Detection And Ranging) and photogrammetric technology.

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Characteristics of a Wavelength-swept Laser with a Polygon-based Wavelength Scanning Filter (다면체 거울 스캐닝 파장 필터를 이용한 파장 훑음 레이저의 출력 특성)

  • Ko, Myeong Ock;Kim, Namje;Han, Sang-Pil;Park, Kyung Hyun;Lee, Bong Wan;Jeon, Min Yong
    • Korean Journal of Optics and Photonics
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    • v.25 no.2
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    • pp.61-66
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    • 2014
  • We report the characterization of a wavelength-swept laser (WSL) using a polygon-based wavelength scanning filter and two semiconductor optical amplifiers (SOAs). The output intensity and scanning bandwidth of the WSL depend on the position of the two SOAs in the laser cavity and the coupling ratio of the output fiber coupler. The outputs of the WSL are characterized for coupling ratios of 10%, 30%, 50%, 70%, and 90% for the output fiber coupler. In the setup in which the output fiber coupler is located between the two SOAs, high output power and wide scanning bandwidth can be achieved with an optimized configuration. Using the optimized configuration of the WSL, the intensity increases with the coupling ratio. These results can be used to construct an optimized WSL using the polygon-based wavelength scanning filter.

Application of Scanning Total Station for Efficiency Enhancement of Tunnel Surveys (터널측량의 효율성 향상을 위한 스캐닝 토털스테이션의 활용)

  • Park, Joon-Kyu;Kim, Min-Gyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.4
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    • pp.242-247
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    • 2017
  • Over- and under-excavation are factors that increase construction cost of tunnels, which makes management essential. Total stations have been used for tunnel surveying because GNSS is difficult to use in tunnels. However, it takes much time to acquire data using total stations. In this study, a total station was integrated with a 3D laser scanner and used for tunnel surveying in Namyangju-si, Gyeonggi-do. The scanning total station reduced the work time compared to the conventional method. Furthermore, reports were effectively generated for overbreak and underbreak for each section and compared with the design. In addition, we could analyze both the cross section and scanned area effectively by using the scanning data. This method can improve the efficiency of tunnel surveying work by combining the advantages of a conventional total station and a 3D laser scanner.

Parallel Processing of Airborne Laser Scanning Data Using a Hybrid Model Based on MPI and OpenMP (MPI와 OpenMP기반 하이브리드 모델을 이용한 항공 레이저 스캐닝 자료의 병렬 처리)

  • Han, Soo-Hee;Park, Il-Suk;Heo, Joon
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.2
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    • pp.135-142
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    • 2012
  • In the present study, a parallel processing method running on a multi-core PC-Cluster is introduced to produce digital surface model (DSM) and digital terrain model (DTM) from huge airborne laser scanning data. A hybrid model using both message passing interface (MPI) and OpenMP was devised by revising a conventional MPI model which utilizes only MPI, and tested on a multi-core PC-Cluster for performance validation. In the results, the hybrid model has not shown better performances in the interpolation process to produce DSM, but the overall performance has turned out to be better by the help of reduced MPI calls. Additionally, scheduling function of OpenMP has revealed its ability to enhance the performance by controlling inequal overloads charged on cores induced by irregular distribution of airborne laser scanning data.

Long Distance and High Resolution Three-Dimensional Scanning LIDAR with Coded Laser Pulse Waves (레이저 펄스 부호화를 이용한 원거리 고해상도 3D 스캐닝 라이다)

  • Kim, Gunzung;Park, Yongwan
    • Korean Journal of Optics and Photonics
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    • v.27 no.4
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    • pp.133-142
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    • 2016
  • This paper presents the design and simulation of a three-dimensional pixel-by-pixel scanning light detection and ranging (LIDAR) system with a microelectromechanical system (MEMS) scanning mirror and direct sequence optical code division multiple access (DS-OCDMA) techniques. It measures a frame with $848{\times}480$ pixels at a refresh rate of 60 fps. The emitted laser pulse waves of each pixel are coded with DS-OCDMA techniques. The coded laser pulse waves include the pixel's position in the frame, and a checksum. The LIDAR emits the coded laser pulse waves periodically, without idle listening time to receive returning light at the receiver. The MEMS scanning mirror is used to deflect and steer the coded laser pulse waves to a specific target point. When all the pixels in a frame have been processed, the travel time is used by the pixel-by-pixel scanning LIDAR to generate point cloud data as the measured result.

Measurement of Joint-Orientation and Monitoring of Displacement in Tunnel using 3D Laser Scanning System (3차원 레이저 스캐닝 시스템을 이용한 불연속면의 방향성 측정과 터널 변위 모니터링)

  • Shon, Ho-Woong;Oh, Seok-Hoon;Kim, Young-Kyung
    • Journal of the Korean Geophysical Society
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    • v.9 no.1
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    • pp.47-62
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    • 2006
  • More than 70% of Korean Peninsula is consisted of mountains, so that lots of roads, rail-roads and tunnel,which play a pivotal role in the industry activity, are existed along the rock-slope and in the rock-mass. Thus,it is urgent that tegration of management system through the optimum survey and design of rock-slope excavation, proper stabilization method and database of rock-slope. However, conventional methods have shortcoming with the economy of survey time and human resources, and the overcome of difficulties of approach to the in-situ rock-slope. To overcome the limitation of conventional method, this paper proposed the development of remote measurement system using Terrestrial Laser Scanning System. The method using Terrestrial 3D Laser Scanning System, which can get 3D spatial information on the rock-slope and2)Dept. Geosystem Engineering, Kangwon National University, Korea tunnel, has an advantage of reduction of measurement time and the overcome of difficulties of approach to the in-situ rock-slope/dam/tunnel. In the case of rock-slope, through the analysis of 3D modeling of point-cloud by Terrestrial Laser Scanning System, orientation of discontinuity, roughness of joint surface, failure shape and volume were successively achieved. in the case of tunnel face, through reverse-engineering, monitoring of displacement was possible.

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Development of An Automated Scanning Laser Doppler Vibrometer for Measurements of In-Plane Structural Vibration (평면 구조 진동 측정을 위한 자동화된 스캐닝 레이저 도플러 진동측정기의 개발 및 연구)

  • Kil, Hyun-Gwon
    • Journal of KSNVE
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    • v.7 no.2
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    • pp.231-238
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    • 1997
  • An automated scanning laser Doppler vibrometer (LDV) has been designed, and built to measure in-plane vibration fields over structures. Use of optical fibers allows the compact design of a laser probe head which can be scanned over the vibrating structures. An algorithm for automated self-alignment of the laser probe is developed. The system is completely automated for scanning over the structures, focusing two laser beams at each data point until the detected vibration signal is stable, and for recording and transferring the data to a system computer. The automated system allows one to get extensive data of the vibration field over the structures. The system is tested by scanning a piezoelectric cylindrical shell and a plate excited by a continuous signal and by a pulse signal, respectively. Results show that the automated scanning LDV system can be a useful tool to measure the in-plane vibration field and to detect the elastic waves propagating on the vibrating structures.

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