• Title/Summary/Keyword: Laser threshold

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Error Analysis of the Multi-Frequency Coning Motion with Dithered Ring Laser Gyro INS (Dither를 가지는 링레이저 자이로 항법시스템의 복합 주파수 원추운동 오차 해석)

  • Kim, Gwang-Jin;Lee, Tae-Gyu
    • Journal of Institute of Control, Robotics and Systems
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    • v.7 no.8
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    • pp.697-702
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    • 2001
  • The ring laser gyro(RLG) has been used extensively in strapdown inertial navigation system(SDINS) because of the apparent of having wide dynamic range, digital output and high accuracy. The dithered RLG system has dynamic motion at sensor level, caused by the dithering motion to overcome the lock-in threshold. In this case, an attitude error is produced by not only the true coning of the vehicle motion but also the pseudo coning of the sensor motion. This paper describes the definition of the multi-frequency coning motion and its noncommutativity error to reject the pseudo coning error produced by the sensor motion such as the dithered RLG. The simulation results are presented to minimize the multi-frequency coning error.

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A study on the classifying vehicles for traffic flow analysis using LiDAR DATA

  • Heo J.Y.;Choi J.W.;Kim Y.I.;Yu K.Y.
    • Proceedings of the KSRS Conference
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    • 2004.10a
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    • pp.633-636
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    • 2004
  • Airborne laser scanning thechnology has been studied in many applications, DSM(Digital Surface Model) development, building extraction, 3D virtual city modeling. In this paper, we will evaluate the possibility of airborne laser scanning technology for transportation application, especially for recognizing moving vehicles on road. First, we initially segment the region of roads from all LiDAR DATA using the GIS map and intensity image. Secondly, the segmented region is divided into the roads and vehicles using the height threshold value of local based window. Finally, the vehicles will be classified into the several types of vehicles by MDC(Minimum Distance Classification) method using the vehicle's geometry information, height, length, width, etc

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Development of Digital Holographic Microscopy System for Measurements of Particle Velocities in MR Fluids (MR 유체 입자 속도 계측을 위한 디지털 홀로그래피 현미경 시스템의 개발)

  • Chen, He-Peng;Kang, B.S.
    • Journal of ILASS-Korea
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    • v.21 no.2
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    • pp.88-94
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    • 2016
  • In this study digital holographic microscopy system for measurements of 3-D velocities of particles in MR fluid is developed. Holograms are recorded using either a CCD camera with a double pulse laser or a high-speed camera with a continuous laser. To process recorded holograms, the correlation coefficient method is used for focal plane determination of particles. To remove noise and improve the quality of holograms and reconstructed images, a Wiener filter is adopted. The two-threshold and image segmentation methods are used for binary image transformation. For particle pairing, the match probability method is adopted. The developed system will be applied to measurements of the characteristics of unsteady 3-D particle velocities in MR fluids through the next stage of this study.

Effect of mechanical backside damage upon minority carrier recombination lifetime measurement by laser/microwave photoconductance technique (기계적 후면 손상이 레이저/극초단파 광전도 기법에 의한 소수 반송자 재결합 수명 측정에 미치는 영향)

  • 조상희;최치영;조기현
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.5 no.4
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    • pp.408-413
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    • 1995
  • We investigated the effect of mechanical backside damage upon minority carrier recombination lifetime measurement in Czochralski silicon substrate by laser excitation/microwave reflection photoconductance decay method. The intensity of mechanical damage was evaluated by X-ray double crystal rocking curve, X-ray section topography and wet oxidation/preferential etch methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the threshold full width at half maximum value which affect minority carrier lifetime measurement is about 13 secs.

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Joint Aspecting System using Image Processing (영상처리를 이용한 접합검사 시스템)

  • Kim, A-Hyun;Kim, Young-Soo;Kang, Won-Chan;Oh, Geum-Kon;Kim, Young-Dong
    • Proceedings of the KIEE Conference
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    • 2004.07e
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    • pp.62-67
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    • 2004
  • In this paper, we present the new method for joint aspect inspecting system. We use the image processing and laser maker for light source. We can find the matrial joint status through processing the line pattern which is made by laser maker. To get the line pattern, in first, we had done the preprocss of threshold. If the shape of line had over two segments, then the joint status is abnormal. We show our system efficency by experiment on tire facility.

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CW 및 Pulsed 레이져를 이용한 세라믹 절단

  • 방세윤
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.156-160
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    • 1994
  • Use of engineering ceramics has been increasing due to the outstanding physical and chemical properties. Conventional machining processes, however, are not applicable due to their hardness and brittleness. Laser cutting is a promising alternative for these ceramics. In this study, experimental data of CO $_{2}$ laser cutting of $Al_{2}$ $O_{3}$ and Si $_{3}$ N $_{4}$ are obtained to give a guide in the industry. Results of $Al_{2}$ $O_{3}$ cutting showed extreme weakness to thermal crack and it was found that pulsed beam has to be used for thick $Al_{2}$ $O_{3}$ specimen. Si $_{3}$ N $_{4}$ showed good results for both CW and pulsed beams. Using pulsed beam resulted narrower kerf width with increased surface roughness a nd reduced cutting speed. It was also found that a parameter call path energy is useful for representing minimum threshold value for possible cutting range with pulsed beam.

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Bistable Liquid Crystal Device Realized on Microscopic Orientational Pattern

  • Kim, Jong-Hyun;Yoneya, Makoto;Yokoyama, Hiroshi
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.187-190
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    • 2005
  • Alignment pattern of checkerboard was constructed by the stylus of atomic force microscope. Orientational bistability of the nematic liquid crystal was realized on that frustrated surface alignment. Macroscopic orientational switching between two perpendicular directions took place by an appropriate in-plane electric field. The threshold electric fields decreased in both switching directions as temperature increased. The focused laser heated up only the limited domains in the cell including a light-absorbing medium. Irradiating the laser concurrently with an appropriate electric field, we switched the selected unit domains in the alignment pattern. The switched domains maintained stably the switched direction without the disturbance from the exterior. Extending and repeating this process, we realized extremely fine devices of bistable switching.

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Fourth and Fifth Harmonic Generations of an Nd:YAG Laser using Nonlinear Optical $LiB_{3}O_{5}$ and $CsLiB_{6}O_{10}$ Crystals (비선형 단결정 $LiB_{3}O_{5}$$CsLiB_{6}O_{10}$을 이용한 Nd:YAG 레이저의 4차 및 5차 조화파 발생)

  • Jang Jong Hun;Kim Ji Won;Yun Chun Seop
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.02a
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    • pp.234-235
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    • 2003
  • All solid-state UV lasers provide efficient, clean and semipermanent light sources for various applications, such as eye surgery, microchip lithography. $CsLiB_{6}O_{10}$ (CLBO) is one of the most suitable crystals for UV generation because of its small walk-off, large effective nonlinear susceptibility in UV region and high damage threshold. We produced fourth (266 nm) and fifth (213 nm) harmonic generation of an Nd:YAG laser (1064 nm) with $LiB_{3}O_{5}$ as a second harmonic generation medium and CLBO as a fourth harmonic and fifth harmonic mediums. (omitted)

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The Structural Analysis of Premixed Turbulent Propagating Flames Utilizing the Image Process Technique (화상처리기법에 의한 예혼합 난류전파화염의 구조해석)

  • 라진홍
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.4
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    • pp.593-600
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    • 1999
  • The structure of premixed turbulent flames in constant volume vessel was investigated by using a laser tomography. The flame structure was visualized by passing a laser sheet with 0.2mm thick and 2 cm wide through the turbulent flames to obtain their 2-D images. From the obtained images islands of reactants as well as of products were found at least in the 2-D images when the turbu-lence intensity was above 0.4m/s. Moreover in order to obtain the characteristic flamelet thickness the light intensities of them were digitized and processed into three colors incorporating two appro-priate threshold values in the image analysis. As the result the averaged value of charactertistic flamelet thickness was found to be about two times compared to laminar one.

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High-efficiency High-power Red PQR Laser Array (고효율 고출력 적색 광양자테 레이저 어레이)

  • Kim, Chang-Hun;Sin, Mi-Hyang;Kim, Yeong-Cheon;Jang, Yeong-Heup;Chae, Gwang-Hyeon;Gwon, O-Dae;Seong, Seung-Gi;Han, Seong-Hong
    • Proceedings of the Optical Society of Korea Conference
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    • 2008.07a
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    • pp.317-318
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    • 2008
  • High-efficiency high-power red PQR (photonic Quantum Ring) lasers with low threshold currents have been fabricated for low cost and low power consumption, whose structure is based upon high-power LED epi-wafers modified for vertically dominant PQR helix resonance. Preliminary experimental results are very promising for panel-less PQR laser chip TV applications.

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