• Title, Summary, Keyword: Laser scanning

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The Evaluation of Accuracy for Airborne Laser Surveying via LiDAR System Calibration (시스템 초기화(Calibration)에 따른 항공레이저측량의 정확도 평가)

  • 이대희;위광재;김승용;김갑진;이재원
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • pp.15-26
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    • 2004
  • The calibration for systematic error in LiDAR is crucial for the accuracy of airborne laser scanning. The main error is the misalignment of platforms between INS(Inertial Navigation System) and Laser scanner For planimetrical calibration of LiDAR, the building is good feature which has great changes in height and continuous flat area in the top. The planimetry error(pitch, roll) is corrected by adjustment of height which is calculated from comparing ground control points(GCP) of building to laser scanning data. We can know scale correction of laser range by the comparison of LiDAR data and GCP is arranged at the end of scan angle where maximize the height error. The area for scale calibration have to be large flat and have almost same elevation. At 1000m for average flying height, The Accuracy of laser scanning data using LiDAR is within 110cm in height and ${\pm}$50cm in planmetry so we can use laser scanning data for generating 3D terrain surface, expecically digital surface model(DSM) which is difficult to measure by aerial photogrammetry in forest, coast, urban area of high buildings

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Analysis of Frequency Response of Piezo Stages and Scanning Path Monitoring/Compensation for Scanning Laser Optical Tweezers (주사 레이저 광집게를 위한 압전 구동기 주파수 특성 분석과 주사 경로 추적 및 보상)

  • Hwang, Sun-Uk;Lee, Song-Woo;Lee, Yong-Gu
    • Korean Journal of Optics and Photonics
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    • v.19 no.2
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    • pp.132-139
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    • 2008
  • In scanning laser optical tweezers, high speed scanning stages are used to manipulate a laser beam spot. Due to the inertia of the stage, the output scanning signal decreases with increased frequency of the input signal. This discrepancy in the signals is difficult to observe since most of the energy from the laser beam is blocked out to avoid CCD damage. In this paper, we propose two methods to alleviate these problems. Firstly, frequency responses of piezo stages are measured to analyze the signal drops and the input signal is compensated accordingly. Secondly, an overlay of the scanning path is drawn on the live monitoring screen to enhance the visibility of the scanning path. The result is a drop-compensated scanning with clear path view.

Three-dimensional vibration measurement algorithm using one laser scanning vibrometer (한대의 LSV 를 이용한 3 차원 진동측정방법)

  • Kim, Dong-Kyu;Song, Ha-Jun;Park, Kyi-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.935-939
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    • 2012
  • 3D vibration measurement is achieved using one laser scanning vibrometer(LSV) and Laser scanner(LS) by moving the LSV to three arbitrarily locations from the principle that vibration analysis based on the frequency domain is independent of the vibration signal based on time domain. The proposed system has the same effect as using three sets of LSVs. It has an advantage of reducing equipment costs. Analytical approach of obtaining in-plane and out-of-plane vibration of surface is introduced using geometrical relations between three LSV coordinates and vibration measured at three different locations.

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QUANTITATIVE ANALYSIS OF MINERAL CHANCE IN THE INITIAL CAR10US LESION USING CONFORMAL LASER SCANNING MICROSCOPY (공초점 레이저 주사 현미경을 이용한 법랑질 초기 우식 재광화의 정량적 분석)

  • 차승우;윤태철;박성호;이찬영;금기연
    • Restorative Dentistry and Endodontics
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    • v.26 no.1
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    • pp.1-8
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    • 2001
  • Dental Caries which has high prevalence rate, accounts for majority of dental diseases. Many treatment and preventive treatment has been developed, thereby reducing the prevalence rate, but in our country, fluoridization has not spread widely yet, so prevention has not been done satisfactorily. When dental caries progresses, irreversible damage of tooth structure occurs. In initial dental caries, demineralizing tooth structure can be remineralized, so restorative treatment is unnecessary. In this study, 20 teeth restored with composite resin without fluoride release were used and divided into two groups. Incipient dental caries were artificially made and demineralization procedure was done for 1 and 2 weeks, for each group. Changes in mineral contents around the margins were analysed with confocal laser scanning microscope. The results were as follow. 1. Both total fluorescence of the lesion and average fluorescence of the lesion of remineralized samples decreased compared to demineralizing state. (p<0.01) 2. Confocal laser scanning microscopy can be used in quantitative analysis of mineral change. In result, confocal laser scanning microscopy can be used in quantitative analysis of mineral change and it could be used in many different fields of dentistry in the future.

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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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Laser scanning unit with plastic f$\theta$ lenses featuring high resolution (600DPI용 플라스틱 f$\theta$렌즈가 실장된 Laser Scanning Unit 의 측정 및 평가)

  • 임천석
    • Korean Journal of Optics and Photonics
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    • v.10 no.5
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    • pp.364-368
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    • 1999
  • We investigate the evaluation items of LSU (Laser Scanning Unit), such as beam size, f$\theta$ characteristics, linearity, skew and bow, optical power ratio between image height of 0mm and $\pm$108 mm, pitch error, Jitter and shift of printing position. Through the measurement of LSU using BSH (Beam Scan Head) installed on LMC (Linear Motion Controller) which moves linearly within the whole scanning range (-108 mm~+108 mm), we can ascertain plastic f$\theta$ lenses, which are manufactured by TVLP (Two-step Variable Low Pressure) molding method, to satisfy 600DPI(Dots Per Inch) performance.

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Position Control of Laser Scanning Mirror Using Piezoelectric Actuator (압전작동기를 이용한 레이져 스케닝 미러의 위치제어)

  • 지학래;김재환;최승복
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.442-445
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    • 1995
  • This paper presents the position tracking control of a laser scanning mirror system in which piezoelectic actuator is incorporated. Using the shear mode of the piezoelectric actuator,angular oscillation of a laser scanning mirror is derived. Torsion bar is rhen designed and attached to the piezoelctric actuator in order to magnify the amplitude generated by the actuator. Finite element modeling and analysis are essntial for designing the piezoelectic actuator. The torsional resonance mode of the piezoelectric actuator is found from the model analysis of the actuator and the mechanical shear is matched with the driving frequency. Transfer function between the electrical excitation and the mechanical shear deformation at resonance frequency is found form the response of the actuator calculated by the finite element analysis and the governing equation of the system is derived from d'Alembert's principle. Tracking control performance for desired trajectory which is, in fact, sinusoidal curve is presented in order to demonstrate the validity of the proposed system.

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Analysis of single/poly crystalline Si etching characteristics using $Ar^+$ ion laser ($Ar^+$ ion laser를 이용한 단결정/다결정 Si 식각 특성 분석)

  • Lee, Hyun-Ki;Park, Jung-Ho;Lee, Cheon
    • Proceedings of the KIEE Conference
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    • pp.1001-1003
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    • 1998
  • In this paper, $Ar^+$ ion laser etching process of single/poly crystalline silicon with $CCl_{2}F_{2}$ gas is studied for MEMS applications. To investigate the effects of process parameters, laser power, gas pressure, scanning speed were varied and multiple scanning was carried out to obtain high aspect ratio. In addition, scanning width was varied to observe the trench profile etched in repeating scanning cycle. From the etching of $2.6{\mu}m$ thick polycrystalline Si deposited on insulator, trench with flat bottom and vertical side wall was obtained and it is possible to apply this results for MEMS applications.

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A Study on Transport Mechanism of the Ultrasonic Transporting System using Laser Scanning Vibrometer (Laser Scanning Vibrometer를 이용한 초음파 이송시스템의 이송 메커니즘에 관한 연구)

  • 정상화;신병수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.841-844
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    • 2003
  • In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. These systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the vibration behavior of flexural beam in the ultrasonic transport system is verified using Laser Scanning Vibrometer. The experiments for verifying vibration are performed in three conditions such as in the maximum transport speed, in the zero speed, and in the change of transport direction.

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Accuracy Estimation of Laser scanning Mobile Mapping System using Lynx Mobile Mapper (Lynx Mobile Mapper를 이용한 레이저스캐너 기반 차량 MMS의 정확도 평가)

  • Jeong, Tae-Jun;Yun, Hong-Sic;Hwang, Jin-Sang;Kim, Yong-Hyun;Wi, Gwang-Jae;Lee, Ha-Jun
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • pp.69-71
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    • 2010
  • In this paper, we focus on the accuracy estimation of laser scanning mobile mapping system using Lynx Mobile Mapper. For this, we surveyed checkpoints(181 points) in study areas. A method to estimate the accuracy of laser scanning mobile mapping system based on the measurement range, interval of control points and gps signal environments. As a result, to ensure reliable measurement results, we must be made a plan considering Measure range(60m or under) and operation. The estimation results showed the need for improving accuracy using control points about 150m interval according to environment error source.

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